Micro Flashcards

Question

# DISEASE: **recent URTI** CXR = cavity microscopy = `+ve cocci clusters` 1. Causative organism? 2. BONUS: which protein enzyme +ve? 3. Mx?

Answer 1

1. Staph aureus (typical) 2. coagulase +ve 3. Flucloxacillin

Answer 2

1. Klebsiella pneumoniae (typical) 2. -ve bacilli

Answer 3

1. legionella pneumophilia 2. Clarithromycin + rifampicin

Answer 4

1. Mycoplasma pneumoniae 2. Macrolide e.g. clarithromycin

Answer 5

1. Chlamydia psittaci

Answer 6

Coxiella burnetii (AKA Q fever)

Answer 7

`Bordetella pertussis` (AKA **whooping cough**) Mx = Abx if cough < 21 days of onset --> **macrolides**: < 1 month old = `clarithromycin` >1 month old = `azithromycin` (if macrolides CI, consider co-amoxiclav) Return to school 2 days after commencing abx Tx **OR** 21 days after cough onset

Answer 8

1. Mycoplasma tuberculosis (AKA TB) 2. gram +ve bacilli

Answer 9

1. Burkholderia cepecia

Answer 10

Pseudomonas aeruginosa Mx = Tazocin **OR** ciprofloxacin +/- gentamicin

Answer 11

aspergillus fumigatus

Answer 12

1. Pneumocystitis jiroveci 2. silver stain +ve 3. co-trimoxazole

Answer 13

HAP = develop pneumonia >2 days after being admitted to hospital Mx = ciprofloxacin + vancomycin Severe HAP Mx = tazocin + vancomycin

Answer 14

tazocin + metronidazole

Answer 15

clindamycin +/- metronidazole

Answer 16

1. Bronchitis: affects normal sized vessels, `normal CXR` 2. Pneumonia: **unwell** pt + affects lung parenchyma 3. Abscess: `swinging fevers` + cavity in lung parenchyma, FLAWS, **unresponsive to abx + requires drainage** 4. Emphysema = infected pleural effusion

Answer 17

1. bacteria form vegetations on valve(s) 2. Usually affects the valves on the **L side** = `mitral` and aortic --> this is due to increased pressure on L side of heart which causes damage to those valves making it more susceptible to bacterial growth NOTE: R sided (tricuspid) is most common in **IVDU** (as circulation returns to R side of heart first) 3. S&S: ACUTE = **fever** (pyrexia of unknown origin (PUO)); `new heart murmur` that changes day to day (usually regurgitant), non specific Sx (anorexia, weight loss, malaise, fatigue etc.); **HF, rapidly septic** NOTE: in subacute infective endocarditis (develops over weeks-months) --> new heart murmur + FLAWS + **embolic phenomena** (e.g. `janeway lesions, splinter haemorrhages, splenomegaly`) & **immune phenomena** (e.g. `roth spots` in eyes, `osler's nodes` in hands, `haematuria due to glomerulonephritis`) 4. Ix: **Blood cultures** = ideally from 3 different sites before starting abx; **echocardiogram**; `DUKE'S CRITERIA`: need 2 major OR 1 major + 3 minor OR 5 minor

Answer 18

Major: * **Positive blood culture** growing typical organisms (>2x cultures >12 hrs apart) * **New regurgitant murmur** OR evidence of vegetation on **echo** Minor: * **RFs**: long-term lines (e.g. in ITU), IVDU, poor dentician, prosthetic valve, rheumatic heart disease, immunosuppression * **Fever** **>38°C** * Embolic phenomena (e.g. `janeway lesions, splinter haemorrhages, splenomegaly`) * Immune phenomena (e.g. `roth spots` in eyes, `osler's nodes` in hands, `haematuria due to glomerulonephritis`) * Positive blood culture not meeting the major criteria For infective endocarditis diagnosis: need **2 major** OR **1 major + 3 minor** OR **5 minor**

Answer 19

`IV abx for 6 weeks` Start empirically as soon as cultures taken, then change according to sensitivities Rule of thumbs: **ACUTE**: `flucloxacillin` (cause staph aureus most common) **SUBACUTE**: `benzylpenicillin + gentamicin` **Prosthetic** valve: `vancomycin + gentamicin + rifampicin` Consider surgical debridement

Answer 20

1. **ACUTE** (`high` virulence bacteria = rapid onset of symptoms): * Streptococcus `pyrogenes` (Group A strep) = **rheumatic fever** * `Staph aureus` (most common in **IVDU**) * `Coagulase-negative staphylococci` (most common in **prosthetic valve**) 2. **SUBACUTE** (`low` virulence bacteria = slower onset of symptoms): * `Staphylococcus epidermidis` (most common **post-valvular surgery**) * Streptococcus `viridans` (more common in low resource countries, dental work) * **HACEK** = do not grow on culture --> `h`aemophilus, `a`cinetobacter, `c`ardiobacterium, `e`ikinella, `k`ingella

Answer 21

1. **staphylococcus epidermidis** (coagulase negative staphylococcus) 2. Mx = IV `vancomycin + gentamicin + rifampicin` BONUS: fulfils 1 major and 3 minor of Duke's criteria

Answer 22

1. staph aureus (infective endocarditis) 2. IV `flucloxacillin`

Answer 23

1. Strep pyogenes AKA group A strep (AKA rheumatic fever)

Answer 24

2. streptococcus viridans (causing infective endocarditis)

Answer 25

1. **Secretory diarrhoea**: `watery diarrhoea, no fever` * Toxin production causes Cl- to be secreted into the lumen which leads to diarrhoea = loss of water + electrolytes * **Organisms**: vibrio **cholerae** (`rice water stool`), enterotoxigenic Escherichia Coli (**ETEC**; `traveller's diarrhoea`), Enteropathogenic Escherichia coli (**EPEC**), **bacillus cereus** (`reheated rice`), s**taph aureus** (`short incubation period`) 2. **Inflammatory diarrhoea**: `BLOODY diarrhoea w/ mucus (AKA dysentery)`, **fever** * Inflammation + bacteraemia * Organisms: **CHESS** * `C`ampylobacter jejuni (complication = GBS), `h`aemorrhagic E. coli, `E`ntamoeba histolytica, `S`higella, `S`almonella 3. Enteric fever: unwell with fever, GI symptoms * Organisms: **salmonella typhi** (typhoid fever), **yersinia** enterocolitica, brucella

Answer 26

1. **Clostridium botulinum**: toxin blocks Ach release from peripheral nerves = `DESCENDING paralysis`; toxin can be **inactivated by cooking**; from canned / vacuum packed `foods` (honey = kids, beans = students); Mx = antitoxin 2. **Clostridium perfringens**: from reheated meats; 8-16hr incubation and lasts **~24hrs**; **watery diarrhoea + cramps**; causes `gas gangrene` (alpha toxin in infected tissue necroses + releases foul smelling gas) 3. **Clostridium difficile**: causes `pseudomembranous colitis` (looks like **wet cornflakes** on colonscopy); caused by the **4 C's** (`c`ephalosporins, `c`lindamycin, `c`iprofloxacilin, `c`o-amoxiclav); Mx = `IV metronidazole or oral vancomycin` 4. **Bacillus cereus**: cereulide toxin; `reheated fried rice`; watery **non-bloody diarrhoea** + vomiting within **4hrs**; self-limiting 5. **Staphylococcus aureus**: S. aureus enterotoxin = vomiting + watery **non-bloody diarrhoea** with `SHORT incubation period` (< 2hrs); self-limiting 6. **Listeria monocytogenes**: microscopy shows tumbling motility; refrigerated food e.g. `CHEESE` (unpasteurised dairy); **perinatal** infection; severe infection in immunocompromised; Mx = **ampicillin** NOTE: ALL are gram +ve bacilli except staph aureus (which is gram +ve diplococci in clusters)

Answer 27

1. (entero`t`oxigenic) Escherichia coli (**E`T`EC**): `t`oxigen, `t`raveller's diarrhoea 2. (entero`p`athogenic) Escherichia coli (**E`P`EC**): `p`athogenic, `p`aediatric/infantile diarrhoea 3. (entero`i`nvasive) Escherichia coli (**E`I`EC**): `i`nvasive; **bloody diarrhoea w/cramps** + N/V 4. (entero`h`aemorrhagic) Escherichia coli (**E`H`EC**): `h`aemorrhagic --> **haemolytic uraemic syndrome** (HUS) = triad of **thrombocytopenia**, MAHA (**anaemia**) and **AKI**; caused by `Shiga toxin`-producing E.coli (STEC) 0157:H7 5. **Salmonella typhi**/ paratyphi: typhoid (/ paratyphoid) fever; faecal-oral route; **rose spots**, `constipation > diarrhoea`, multiplies in Peyer’s patches; Mx = **IV ceftriaxone** then PO azithromycin; complication = osteomyelitis in SCA 6. **Salmonella enteritides**: contaminated poultry, eggs (`BBQ`); non-bloody diarrhoea, abdominal pain that comes and goes in waves; self-limiting (or ceftriaxone if required) NOTE: **vibrio** = `comma-shaped` bacteria 7. **Vibrio cholera**: comma-shaped bacteria; **enterotoxin** A + B; `rice water stool`, severe dehydration that leads to weight loss; Mx: self-limiting (or doxycycline if required) 8. **Vibrio parahaemolyticus**: comma-shaped bacteria; cruise ships / Japan = **undercooked / raw seafood**; ~3 days of diarrhoea; Mx: **doxycycline** 9. **Vibrio vulnificus**: comma-shaped bacteria; ; causes `cellulitis` in **shellfish handlers**; if PMH of **HIV** = can cause **sepsis**, D+V; Mx: **doxycycline** 10. **Campylobacter jejuni**: also **comma**-shaped bacteria gram -ve, oxidase +ve; `unpasteurised milk and poultry (mainly chicken)`; prodrome of headache and fever; watery **diarrhoea** that turns bloody; complication = **Guillain-Barre syndrome**; Mx = if in first 5 days, **erythromycin or ciprofloxacin** 11. Shigella: Shiga toxin (inactivates 60S ribosome) ; bloody diarrhoea w/pain; Mx = if not self-limiting then **ciprofloxacin** 12. **Yersinia enterocolitica**: faecal-oral route, Peyer’s patches, enterocolitis; complication = **reactive arthritis** `NOTE: ALL gram -ve bacilli`

Answer 28

1. **Entamoeba histolytica**: `dysentery` --> mobile trophozoite w/ **4 nuclei**, main RF = **MSM**; if trophozoites enter portal vein it causes **liver** `cyst/abscess` (anchovy paste appearance); `flask-shaped` **ulcer**; Mx = **metronidazole + paromomycin** 2. Giardia lamblia: **pear-shaped** trophozoite w/ **2 nuclei;** prolonged smelly, explosive non-bloody diarrhoea; biopsy = `partial villous atrophy`; Mx = **Metronidazole** 3. **Cryptosporidium parvum**: severe diarrhoea in `immunocompromised`; **Kinyoun acid-fast stain** w/oocytes in stool; Mx = **Paromomycin**

Answer 29

1. **Rotavirus**: most **common** cause in `children`; w/ **fever + vomiting**, watery diarrhoea 2. **Norovirus**: G2.4 predominant strain; `lots of vomiting`; can cause outbreaks in adults 3. **Adenovirus**: infants (often immunocompromised); non-bloody diarrhoea

Answer 30

Clostridium botulinum --> botulism toxin Mx = antitoxin

Answer 31

1. clostridium perfringens 2. RFs = **reheated meat**; incubation period of 8-16hrs, Sx lasts 24hrs NOTE: foul smelling gas suggestive of `gas gangrene`

Answer 32

1. clostridium difficile --> causes `pseudomembranous colitis` (looks like **wet cornflakes** on colonscopy) NOTE: other complications include toxic megacolon 2. 4 C's = `c`ephalosporins, `c`lindamycin, `c`iprofloxacilin, `c`o-amoxiclav 3. IV **metronidazole** or oral **vancomycin**

Answer 33

**bacillus cereus** --> self-limiting RF = `reheated rice`, incubation period ~4hrs

Answer 34

1. **staphylococcus aureus** --> short incubation period + self-limiting 2. gram +ve diplococci in `clusters`

Answer 35

listeria monocytogenes Mx = ampicillin, ceftriaxone, co-trimoxazole

Answer 36

ETEC (enterotoxigenic E. coli) --> gram -ve bacilli

Answer 37

E`P`EC (enteropathogenic E. coli) = `p`aeds

Answer 38

haemolytic uraemic syndrome (**HUS**) --> caused by **EHEC** `0157:H7` (enterohemorrhagic Escherichia coli) which releases **Shiga toxin**

Answer 39

1. **salmonella typhi** (AKA typhoid fever) 2. osteomyelitis in SCA pts 3. IV ceftriaxone then PO azithromycin

Answer 40

1. Salmonella enterides 2. self-limited, resolves in ~3 days (or ceftriaxone if required)

Answer 41

1. Vibrio cholera 2. enterotoxins A + B 3. self-limiting (if not doxycycline) | NOTE: all vibrios are comma shaped

Answer 42

1. vibrio parahaemolyticus 2. doxycycline

Answer 43

1. Vibrio vulnificus 2. Doxycycline

Answer 44

1. Campylobacter jejuni 2. complication = **Guillain-Barre syndrome** 3. Mx = if in first 5 days, **erythromycin or ciprofloxacin**

Answer 45

Yersinia enterocolitica

Answer 46

1. Entamoeba histolytica (protozoa) 2. Mx = **metronidazole + paromomycin**

Answer 47

1. giardia lamblia (protozoa) 2. Mx = oral **Metronidazole**

Answer 48

1. Cryptosporidium parvum (protozoa) 2. Mx = **Paromomycin**

Answer 49

**Uncomplicated** = women **Complicated** = `men`, `catheters`, `pregnancy`, functionally / structurally abnormal tract **Lower** = affects only the `bladder` **Upper** = affects `kidneys`, systemically unwell * **Urinalysis** (not typically done in men, women > 65 y/o or catheterised): shows `↑` `nitrites` (specific for UTI) and ↑ leukocytes (founnd in any inflammatory condition of the urinary tract) * **Urine culture**: >10^4 colony forming units / ml = `diagnostic` (note: mixed growth or squamous cells suggests contaminated sample) NOTE: >10^3 colony forming units / ml is used for E. coli and S. saprophyticus

Answer 50

1. **Uncomplicated**: `nitrofurantoin` (or trimethoprim) for `3` days 2. **Complicated** (e.g. male or previous Hx w/resistant organisms): `nitrofurantoin` (or trimethoprim / cefalexin) for `7` days 3. **Pyelonephritis**: admit + `IV co-amoxiclav` / amikacin / cefalexin 4. **Pregnancy**: `nitrofurantoin` (but congenital malformations at 3rd trimester), at term = `co-amoxiclav/cefalexin`/trimethoprim NOTE: **nitrofurantoin** can increase the risk of `haemolytic anaemia in newborn` if administered close to term; and **trimethoprim** (`folate antagonist`) can cause neural tube defects if administered in the `first trimester` 5. **Catheter**-associated: `remove catheter` + aminoglycoside (e.g. `gentamicin`) **OR** if `candida`, then no antifungal unless awaiting renal transplant (then oral fluconazole) BONUS: **trimethoprim is a folate antagonist**, therefore it is NOT prescribed if pt is on `methotrexate`!

Answer 51

1. `Escherichia coli` (**most common**) = `lactose fermenting` gram -ve bacilli; classically **young women** who are `sexually active`); 2. `Staphylococcus saprophyticus` = gram +ve cocci in clusters; **2nd most common** in young women; `catalase +ve, coagulase -ve`; associated with catheters; has **p-fimbriae** (a protein) that allows adherence to the urinary tract 3. `Staphylococcus aureus` = gram +ve cocci in clusters; `catalase +ve, coagulase +ve`; most common cause of **haematogenous spread** so take blood cultures as likely to have bacteraemia 4. `Staphylococcus epidermidis` = gram +ve cocci; indwelling catheter; catalase +ve, coagulase -ve 5. `Proteus mirabilis` = gram -ve bacilli; associated with **kidney stones** --> struvite stones (`staghorn` calculi), **young boys** NOTE: this is because proteus mirabilis produce urease, which converts ammonia to urea, which leads to alkaline urine pH and struvite crystals 6. `Klebsiella` = `lactose fermenting` gram -ve bacilli; associated w/ **immunocompromised + indwelling catheter** 7. `Enterobacter` = `lactose fermenting` gram -ve bacilli; associated w/ **immunocompromised** 8. `Candida albicans` = fungus; **catheter-associated**

Answer 52

1. E. coli 2. Klebsiella 3. Enterobacter

Answer 53

1. E. coli 2. gram -ve bacilli (lactose fermenting)

Answer 54

Staphylococcus saprophyticus catalase +ve, coagulase -ve Mx = 3 days nitrofurantoin

Answer 55

1. `proteus mirabilis` (-ve bacilli) 2. proteus mirabilis produces urease --> converts ammonia to urea, which leads to alkaline urine pH and **struvite crystals** (kidney stones - AKA staghorn calculi)

Answer 56

1. candida albicans 2. remove catheter, no Mx unless pt awaiting renal transplant (then oral fluconazole)

Answer 57

Klebsiella NOTE: enterobacter also lactose fermenting gram -ve bacilli found in immunocompromised pts (not associated with catheters though)

Answer 58

1. Staph aureus 2. 7 days nitrofurantoin (because men = complicated = longer abx duration)

Answer 59

1. **Septic arthritis**: `neisseria gonorrhoea` in young pts; `staphylococcus aureus`> strep > E. coli in older pts * RFs: pre-existing arthritis, diabetes, CKD, liver failure * S&S: pyrexia, swollen joint (knee most likely affected), red, hot and reduced movement * Ix: joint aspirate * Mx: drain joint + `IV cefotaxime` for N. gon; `IV fluclox` for staph 2. **Osteomyelitis**: `staphylococcus aureus`, or `salmonella if SCA`, or `pseudomonas if IVDU` * S&S: lumbar most affected region = vertebral pain, * Mx = `IV fluclox` for staph aureus, `IV piperacillin` for pseudomonas cover * Radical debridement if chronic osteomyelitis 3. **Prosthetic joint infection**: `CoNS` (coagulase-negative staphylococci) e.g. staph `epidermis` * Signs same as septic arthritis * Radiology would show **loosening of the bone** * Mx: remove prosthesis + `IV vancomycin` and `oral rifampicin` 4. **Surgical site infection**: `staph aureus` > E. col > strep * 2nd most common HAI * Mx = oral/IV `flucloxacillin` OR if (suspected) MRSA = IV `vancomycin/linezolid`

Answer 60

Septic arthritis --> due to **Neisseria gonorrhoea** (gram -ve diplococci) Mx = drain joint + `IV cefotaxime`

Answer 61

1. osteomyelitis (lumbar region most commonly affected) --> **staph aureus** = most common causative organism 2. Mx = `IV flucloxacillin`; chronic osteomyelitis = surgical debridement

Answer 62

1. **salmonella typhi** 2. **pseudomonas aureginosa**

Answer 63

1. prosthetic joint infection --> **staphylococcus epidermis** (or other CoNS = coagulase neg staph) 2. remove prosthesis + `IV vancomycin` and `oral rifampicin`

Answer 64

1. surgical site infection --> **staph aureus** 2. IV `flucloxacillin`

Answer 65

**Meningitis** = inflammation of `meninges` * S&S = **meningism** e.g. stiff neck, photophobia, headache * Ix = LP > abx; gram stain for bacteria, PCR for virus, India ink stain for cryptococcus, ZN stain for TB VS **Encephalitis** = inflammation of the `brain parenchyma` * S&S = meningism + **altered mental status** e.g. confusion, fluctuating consiousness

Answer 66

**1. Bacterial**: CSF = **very high** `neutrophils`, high protein, low glucose * **Neisseria meningitidis** (gram `-ve`), **streptococcus pneumoniae** (gram `+ve`) * **Ix = gram stain** * Neonates: GBS, listeria monocytogenes, E. coli * Elderly: GBS, listeria monocytogenes * `RFs for N. meningitidis` = complement deficiency, hyposplenism (NHS), hypogammaglobulinaemia * `RFs for strep. pneumoniae` = complement deficiency, hyposplenism (NHS), immunosuppressed (alcoholic), infection (pneumonia), previous head trauma w/ CSF leak * Mx = `IV ceftriaxone + corticosteroids` (+ listeria cover for neonates / elderly w/ **ampicillin**) **2. Viral:** CSF = **very high** `lymphocytes`, high protein, normal glucose * `Enteroviruses` e.g. coxsackie, echovirus * Mumps * `HSV2` * **Ix = PCR** **3. Fungal:** * Cryptococcus neoformans (chronic) --> **India ink stain** **4. TB:** CSF = high `lymphocytes`, `VERY HIGH protein`, low glucose * CHRONIC meningitis * **Ix = Ziehl-Neelson stain** * Mx: Dexamethasone w/anti-TB drugs * MRI: **leptomeningeal enhancement**

Answer 67

Most commonly caused by `HSV 1` Ix = temporal + inferior frontal lobes affected Mx = **IV aciclovir**

Answer 68

1. **Myelitis**: `poliovirus`; Sx = `paralysis` w/ preceding muscle fasciculations 2. **Tetanus**: `clostridium tetani`; RFs = IVDU; `tetanospasmin` prevents GABA + glycine release, which leads to **rigid spastic paralysis**, lockjaw (trismus), opisthotonos (arched back); Mx = `metronidazole` 3. **Brain abscess**: staph / strep; **TRIAD**: `headache` (dull, persistent), `swinging fever` + `focal neurology` (due to space occupying lesion); Ix = **ring-enhancing lesion**; Mx = **craniotomy** w/ `IV ceftriaxone + metronidazole`

Answer 69

**1. Sporadic**: codon 129 – MM polymorphism * Demented `LAMB` =`l`ower motor neuron signs, `a`kinetic mutism, `m`yoclonic jerks and cortical `b`lindness) * EEG = periodic **triphasic** sharp wave complexes * LP = 14-3-3 + S100 **protein** * Autopsy= spongiform vacuolation, `PrP` **amyloid plaques** **2. Genetic**: PRNP P102L (GSS syndrome)/PRNP D178N (FFI) --> **TWO** types: * **Gerstmann-Strausslet-Sheinker** syndrome: ADD = slowly progressive `a`taxia, `d`iminished reflexes, `d`ementia * **Familial fatal insomnia**: `untreatable insomnia` (agrypnia excitata), dysautonomia, late cognitive decline, die from lack of sleep **3. Acquired:** variant – Bohvine-Johne’s Disease in cows (`Mad Cow Disease`) * Young patients * `Psychiatric Sx` e.g. anxiety, paranoia and hallucinations, then dementia * Ix: `tonsillar biopsy` (gold-standard), **pulvinar** sign (**nuclei in thalamus**) * Autopsy = **florid plaques**

Answer 70

* **`Bacterial`**: turbid CSF, LOW glucose, HIGH WCC (polymorphs AKA `neutrophils`) * **Partially treated** `bacterial`: turbid CSF, **NORMAL glucose**, HIGH WCC (polymorphs AKA `neutrophils`) * **Viral**: `clear` CSF, NORMAL glucose, HIGH WCC (mononuclear AKA `lymphocytes`) * **TB**: clear or turbid CSF, `VERY LOW glucose`, HIGH WCC (mononuclear AKA **lymphocytes**)

Answer 71

1. **bacterial meningitis** (due to `↑ neutrophils` in CSF) --> `< 3 months` so could be neisseria meningitidis, streptococcus pneumoniae OR listeria 2. Mx = `IV ceftriaxone AND ampicillin` (for **listeria** cover) BONUS: gram stain for bacterial causes ## Footnote meow

Answer 72

1. `viral meningitis` (due to`↑ lymphocytes` in CSF) --> most likely due to **mumps** virus (unvaccinated, **parotitis**) 2. Ix = `IgM mumps detection` 3. Mx = supportive usually for viral NOTE: could give IV aciclovir if herpes cause

Answer 73

1. TB meningitis --> mycobacterium tuberculosis (due to `↓↓↓ glucose, ↑ lymphocytes`) 2. Ziehl-Neelson = stain carbol fuschin & methylene blue --> AFB go `red` on a blue background 3. Mx = **dexamethasone w/ anti-TB drugs**

Answer 74

1. encephalitis --> HSV1 (most common) 2. IV aciclovir

Answer 75

**(polio)myelitis** --> `poliovirus` Normally, IPV (inactive polio vaccine) given as a part of 6 in 1 (2, 3, 4 months), 4 in 1 (3yrs + 4months), and 3 in 1 (14 years)

Answer 76

1. Tetanus --> `clostridium tetani` 2. Mx = metronidazole

Answer 77

1. Brain abscess --> strep or staph 2. Brain MRI = ring-enhancing lesion 3. Mx = **craniotomy** w/ `IV ceftriaxone + metronidazole`

Answer 78

**1. Sporadic prion disease** NOTE: Sx = demented `LAMB` =`l`ower motor neuron signs, `a`kinetic mutism, `m`yoclonic jerks and cortical `b`lindness) NOTE: cortical blindness is loss of vision w/o opthalmologic cause and preserved pupillary light reflexes 2. EEG = periodic **triphasic** sharp wave complexes; LP = 14-3-3 + S100 **protein**; autopsy = spongiform vacuolation, `PrP` **amyloid plaques**

Answer 79

Genetic Gerstmann-Strausslet-Sheinker (one of the genetic prion diseases)

Answer 80

Familial fatal insomnia (**UNTREATABLE** `insomnia`)

Answer 81

1. variant of Bohvine-Johne’s Disease AKA `Mad Cow Disease` (**acquired prion disease**) 2. `Tonsillar biopsy` --> abnormal prions (gold standard) note: can also do MR --> pulvinar sign (nuclei in thalamus) 3. Autopsy = **florid plaques**

Answer 82

1. **Discharge**: gonorrhoea, chlamydia, trichomonas, candida, BV 2. **Ulceration**: syphilis (`painless` chancre), chancroid, LGV, donovanosis 3. **Rashes, lumps/growths**: genital warts (HPV `6 & 11`), molluscum contagiosum, scabies, pubic lice

Answer 83

**1. Gonorrhoea** --> `neisseria gonorrhoea` (gram **-ve** cocci) * Urethritis / cervicitis, discharge, dysuria (rectal prostitis if MSM) * Mx = `ceftriaxone` **2. Genital chlamydia** --> `chlamydia trachomatis` (-ve coccobacilli) * Often **asymptomatic** (esp. in women, so 1st presentation may be PID / infertility) * Yellow / green `discharge` * **Serovars D-K** cause genital chlamydia * `NAAT` (nucleic acid amplification test) from genital swabs / first void urine confirms diagnosis * Mx = `doxycycline` 100mg BD 7 days OR 1g `azithromycin` stat (e.g. in pregnancy because doxy is teratogenic) **3. Lympho-granuloma venereum** --> `chlamydia trachomatis` (-ve coccobacilli) causes **lymphatic** infection * **Serovars L1, L2 and L3** * `3 stages`: painless ulcer/papule on genitals; then painful inguinal lymphadenopathy; then proctocolitis * Dx = +ve urinary `NAAT` * Mx = **doxycycline** **4. Syphilis** --> `treponema pallidum` (-ve spirochaete) * 1° = `PAINLESS ULCER` (**chancre**) * 2° = widespread rash + **”snail track” ulcers** + condyloma acuminate (genital warts, hypopigmented lesions) * 3° = **THREE** different syndromes: `gumma` (gum-like pus lesion); `CVS` e.g. ascending aortic aneurysm (**AAA**), `neurosyphilis` e.g. arygyll-Robertson pupil + dementia + tabes dorsalis (spinal cord) * `Spirochaetes` in CSF in 3° syphilis * Ix = **dark-field microscopy** (for 1° chancre) shows treponemes * Treponemal = detects Abs against specific antigens which stays +ve long term even after Tx VS non-treponemal tests = detects Abs against non-specific antigens and titres fall w/ effective Tx * Mx = `benzathine benzylpenicillin IM` (doxy if allergic) – monitor with RPR titres + can cause **Jarisch-Herxheimer** reaction (rash, hypotension, fever) **5. Chancroid** --> `haemophilus ducreyi` (-ve coccobacilli) * `PAINFUL` ulcer * unilateral painful inguinal lymphadenopathy * Ix = chocolate agar **6. Donovanosis** --> `klebsiella granulomatis` (-ve bacilli) * **Beefy** `red` **ulcers** * Ix = `Giemsa stain` --> **donavan bodies** * Mx = `azithromycin` **7. Bacterial vaginosis** --> `gardnerella vaginalis` (gram variable) * Smelly white creamy `discharge` * Ix: **Amsel criteria** (clue cells, pH >4.5, whiff test, abnormal vaginal discharge) * Mx: `metronidazole` (even in pregnancy)

Answer 84

**1. Trichomoniasis** --> `trichomonas vaginalis` (flagellated protozoa) * Men = asymptomatic usually (?urethritis); women = **yellow/green discharge**, offensive smelling * pH >4.5 (NOTE: BV is the only other condition w/ pH >4.5 asw) * Ix = speculum --> `strawberry cervix` * Ix = wet slide microscopy (**motile trophozoites**) * Mx = `metronidazole` * Associated w/ ↑ risk of HIV due to disrupted mucosa **2. Candidiasis**/ thrush --> `candida albicans` (yeast) * '`Cottage cheese`' (thick white) discharge * Mx = oral **fluconazole** (BUT cream / pessaries ONLY if pregnant, oral contraindicated) **3. Molluscum contagiosum** --> `poxvirus` * `Small papules w/ central punctum` (widespread if immunocompromised) * Children: spread by skin-to-skin contact, spots on hands & face * Adults: spread via sexual contact, genital lesions * Supportive Mx / cryotherapy if persistent **4. Genital warts** --> HPV 6 & 11 * Mx = **podophyllotoxin** solution / cream (CI pregnancy); 2nd line = cryotherapy in clinic or Imiquimod **5. Examples of viral STIs:** * Hepatitis, HBV, HCV (mainly in HIV +ve MSM), herpes, HIV

Answer 85

1. **Gonorrhoea** (due to `neisseria gonorhoea`) 2. Mx = `ceftriaxone`

Answer 86

1. **PID** (due to `chlamydia trachomatis`) BONUS: gram -ve coccobacilli 2. `Doxycycline` 100mg BD 7 days (azithromycin 1g stat if pregnant)

Answer 87

1. Lymphogranuloma venereum - **LGV** (due to `chlamydia trachomatis`) = infection in lymphatic system 2. Serovars **L1-L3** 3. `Doxycycline` 100mg BD 3 wks

Answer 88

1. currently has **3° syphilis** (due to `treponema pallidum`) NOTE: Sx from 15 years ago are 1° + 2° Currently pt has gumma (gum-like pus lesion) + spinal cord involvement (tabes dorsalis) + CVS involvement (AAA) = 3° 2. Ix = **dark-ground** microscopy to see chancre (treponemes seen) for 3°, Ix = **non-treponemal test** (tests for Abs against non-specific antigens as the titres go down after Tx) NOTE: treponemal test looks for Abs against specific antigens and this stays +ve for many years even after successful Tx 3. **Mx** = `single dose IM benpen` (benzathine benzylpenicillin

Answer 89

**Jarisch-Herxheimer reaction**

Answer 90

1. **chancroid** (due to `haemophilus ducreyi` = -ve coccobacilli) 2. **chocolate** agar

Answer 91

1. **Donovanosis** (due to `klebsiella granulomatis`) 2. Azithromycin

Answer 92

1. **Bacterial vaginosis** (due to `gardnerella vaginalis`) 2. **Amsel criteria**: clue cells, pH >4.5, whiff test, abnormal vaginal discharge 3. Mx: `metronidazole` (even in pregnancy)

Answer 93

1. Trichomoniasis (due to`trichomonas vaginalis`, a flagellated protozoa) 2. Ix = wet slide microscopy --> **motile trophozoites** 3. Mx = `metronidazole` BONUS: associated w/ ↑ risk of HIV due to disrupted mucosa

Answer 94

1. **candidiasis** (due to `candida albicans`, yeast) 2. oral `fluconazole` (unless pregnant, then pessary / topical)

Answer 95

1. molluscum contagiosum 2. supportive Mx (cryotherapy if persistent)

Answer 96

* **Genital warts** (caused by `HPV 6 & 11`, which are normally in the HPV vaccine given at 13 years) NOTE: oncogenic types are HPV 16 and 18 * Mx = **podophyllotoxin** solution / cream (CI pregnancy); 2nd line = cryotherapy in clinic or Imiquimod

Answer 97

1. **Malaria**: `malariae falciparum` (most common), vivax, ovale, knowlesi, malariae 2. **Typhoid**: `salmonella typhi` = gram -ve bacilli 3. **Dengue**: `flavivirus` 4. **Spotty rocky mountain fever**: `rickettsial akari` = gram -ve coccobacilli 5. **Rabies**: `rhabdovirus` 6. **Q fever**: `coxiella burnetti` (BBQ --> CBQ --> house of CB --> coxiella burnetti) = gram -ve coccobacilli 7. **Brucellosis**: `brucella miletensis` = gram -ve coccobacilli 8. **Leptospirosis**: `leptospira interrogans` = gram -ve spirochete 9. **Lyme disease**: `borrelia burgdorferi` = gram -ve spirochete (Avril lavigne --> babiest baby --> BB --> borrelia burgdorferi) 10. **Human plague**: `yersinia pestis` = gram -ve bacilli (yessir pestis) 11. **Anthrax**: `bacillus anthrax` that release a tripartite protein toxin = gram +ve rods 12. **Leishmaniasis**: `leishmania major`/tropica (most common); donovani (Kala Azar) 13. **Sleeping sickness**: `trypanosoma` brucei and Trypanosoma cruzi (Chagas) 14. **Catch scratch disease**: `bartonella henselae` = gram -ve bacilli (cats? chickens? henselae)

Answer 98

* **Plasmodium falciparum**, vivax, ovale, knowlesi, malariae * `Female anopheles mosquito` * Endemic regions / recent travel (PUO in returning traveller from endemic region) * *TIP: Ask if pt took `malaria prophylaxis`* * **Cyclical fevers** (every 48 hrs in falciparum/vivax/ovale and 72 hrs in malariae) * NOTE: can also get cerebral malaria --> leads to coma * Sx of severe falciparum malaria = impaired conscious / seizures, renal impairment, acidosis, hypoglycaemia, pulmonary oedema, anaemia, DIC, shock, haemoglobinuria (without G6PDD) * NOTE: HLA-B53 is protective against severe malaria * Thick and thin `blood films` = 3x **thick** (to check for parasites) and **thin** (to quantify parasitaemia + demostrate the species; if `>2%` in children or `>10%` in adults --> severe) * **Falciparum** = `Maurer’s clefts` in RBCs * Ovale + Vivax = Schuffner dots in RBCs * **Mx** for Falciparum = `oral malarone / IV artesunate` (if severe) * Mx for Ovales + Vivax + Malariae = chloroquine * NOTE: antimalarials can cause acute haemolysis in people with G6PDD BONUS: **blackwater fever** severe complication of plasmodium falciparum malaria characterised by `haemoglobinuria` (AKA dark urine --> 'blackwater')

Answer 99

* **Salmonella typhi** (or paratyphi) = gram -ve bacilli * Faeco-oral spread (**contaminated food** / water) - 1-2 wks incubation * `Enteric fever` (fever + GI Sx) --> due to Peyer's patches * High prolonged fever + headache * `Constipation` > diarrhoea * **Rose spots** * **Relative bradycardia** (AKA Faget sign) --> with high temperature you expect ↑HR, but pt actually has normal HR * GOLD STANDARD = **blood culture** (+/- stool culture) * **Mx** = `IV ceftriaxone, then PO azithromycin` BONUS: typhoid vaccine vaccinates against S. typhi

Answer 100

* **Flavivirus** * `Female aedes mosquito` - short incubation period (days) * SE asia, urban environments * NOTE: **rare in travellers** (unlike malaria) as uncommon to be re-infected * Sx: **fever**, **myalgia**, sunburn rash, retroorbital **headache** * Fever then fucked (critical) before recovery * Ix = ↓Hb, ↓WCC, ↓platelets * **Councilman bodies** (inclusion bodies) in hepatocytes * **Supportive Mx** **BONUS**: dengue haemorrhagic fever = ↑ bleeding; dengue shock syndrome = ↓ BP

Answer 101

* **Rickettsial akari** - gram negative coccobacilli * Liponyssoides sanguineus (`tick`) * Fever + headache + `rash` that starts peripherally (maculopapular to vasculitic) * Myalgia * **Black eschars** * **Mx** = `doxycycline`

Answer 102

* Lyssa virus / **rhabdovirus** * `Dogs` or bats * **Prodrome**: fever + headache + sore throat * `Migration to CNS` (after months - years) = **hypersalivation**, **hydrophobia**, acute **encephalitis** (agitation, seizure) * NOTE: nearly 100% mortality once CNS Sx * Therefore, MUST take prophylactic rabies vaccine! --> `rabies IgG post-exposure vaccination course` * **Ix = IgM** **BONUS**: `negri bodies` in infected neurons | rabies = rhabovirus

Answer 103

* **Coxiella burnetti** = gram -ve coccobacilli * `Cattle / sheep` * Fever * **Atypical pneumonia** (dry cough) or endocarditis * CXR = `ground-glass` appearance * Ix = serology * **Mx** = `doxycycline`

Answer 104

* **Brucella melitensis** = gram -ve bacilli * `Unpasteurised dairy, direct animal contact` (farmers) * **SUDDEN** onset ↑ fever * Returning traveller with **orchitis** + back pain (sacroiliitis) with psoas + liver **abscesses** * **Brucella serology**: `anti-O-polysaccharide` antibody * **Castenada’s** medium * **Mx** = **4-6 weeks** of `doxycycline + gentamicin/streptomycin` * Complications = `MEO`(W): `m`eningoencephalitis, `e`ndocarditis, `o`steomyelitis

Answer 105

* **Leptospiroma interrogans** = gram -ve spirochaete * `Rat urine` * Fever + jaundice + `conjunctival haemorrhages` * RFs = **sewage workers**, farmers * **Mx** = `doxycycline` (or erythromycin) BONUS: in severe disease (Weil’s disease) = AKI, aspetic meningitis

Answer 106

* **Borrelia burgdorferi** = spirochaete * `Ixodes ticks` --> RFs = hiking * EARLY (localised) = bull’s eye rash (`erythema chronicum migrans`), flu-like Sx * EARLY disseminated = fevers, myalgia, arthralgia, CNS/heart block Sx * LATE (persistent) = carditis, malaise, meningitis, **3rd degree heart block** / CNS signs * Ix: **ELISA** to BB then **immunoblot** * **Mx** = `doxycycline` (amoxicillin in pregnancy OR ceftriaxone if disseminated)

Answer 107

* **Yersinia pestis** = gram -ve bacilli, lactose fermenter * `R`ats = `r`esevoir, transmission by `fleas` * NOTE: still seen in some American national parks e.g. Yosemite * Swollen LN = `bubo` * **Dry gangrene** * **Ix = PCR** * **Mx** = `c`auses `d`ry `g`angrene `s`lowly: `c`hloramphenicol + `d`oxycycline + `g`entamicin + `s`treptomycin

Answer 108

* **Bacillus anthracis** = gram +ve rods with tripartite protein toxin * `Cows` * **Cutaneous** = painless `black eschars` * **Pulmonary** = massive lymphadenopathy + `mediastinal haemorrhage` (CP + SOB + haemoptysis) * GI = necrotic ulcers, perforation * **Mx** = `doxycycline / ciprofloxacin`

Answer 109

* **Leishmania major/tropica** (most common) = causes cutaenous * Leishmania brazilensis = muco-cutaenous * **Leishmania donovani** = causes visceral * `Sandfly` * **Cutaneous** (most common) = `scaly ulceration` at sandfly **bite** site * **Muco-cutaenous** = starts off as dermal ulcer, then months-years later `ulcerative mucous membrane destruction` in nose / mouth * **Visceral (Kala Azar)** = massive `splenomegaly`, usually **young malnourished child**, gradual onset fever, abdo discomfort, anorexia / weight loss * Ix: NMN (Novy-Macneal-Nicolle); **splenic aspirate** * **Mx** = `amphotericin B`

Answer 110

* **Trypanosoma brucei** and Trypanosoma cruzi (chagas) * NOTE: African sleeping sickness = Brucei gambiense * T`s`et`s`e fly (`s`leeping `s`ickness) * Brucei `g`ambiense (African) = `g`**radual** **infection** (GG) * Brucei `r`hodesiense = `r`**apid infection** (RR) * **Cruzi** = **acutely** Romana’s sign (`purple eyelid`); **chronically** `dysphagia` due to formation of megaoesophagus and megacolon * **Mx** (early disease) = IV pentamidine; later disease = IV melarsoprol

Answer 111

* **Bartonella henselae** = gram -ve bacilli * `Kitties` * NOTE: cat scratch disease is a severe form of bacillary angiomatosis (a cutaneous infection caused by bartonella) * RFs = immunocompetent * `Macule` at site of **bite** * **Mx** = erythromycin/`doxycycline`

Answer 112

`Thick + thin blood films` * **3x thick** = to check for parasites * Thin = to quantify parasitaemia + demostrate the species; if >2% in children or >10% in adults –> severe

Answer 113

IV artesunate BONUS: blackwater fever

Answer 114

Pseudomonas

Answer 115

1. **Typhoid fever** --> `salmonella typhi` (or paratyphi) 2. faeco-oral (contaminated food) 3. Ix = `blood culture` +/- stool culture (GOLD STANDARD) Mx = IV `ceftriaxone`, then PO `azithromycin`

Answer 116

1. **Dengue fever** = `flavivirus` 2. Female `aedes mosquito` 3. **Councilman bodies** in hepatocytes 4. `Supportive` Mx NOTE: bloods show `↓Hb, ↓WCC, ↓platelets`

Answer 117

1. **Rocky Mountain Spotted Fever** = `rickettsial akari` 2. `Ticks` (liponyssoides sanguineus) 3. Sx = fever + headache + `rash that starts peripherally` (maculopapular to vasculitic) + `black eschars` 4. Mx = **doxycycline**

Answer 118

1. **Rabies** = `rhabdovirus` 2. `Dogs` or bats 3. 100% mortality if CNS S&S NOTE: normally give prophylactic vaccination course with IgG

Answer 119

1. **Q fever** = `coxiella burnetti` 2. `Cattle` (farmers at risk, esp with fluid transmission) 3. CXR = **ground glass** appearance (due to atypical pneumonia presentation); `serology` 4. Mx = **doxycycline**

Answer 120

1. **Brucellosis** = `brucella melitensis` 2. unpasteurised dairy / farm animals 3. Ix = **brucella serology**; `anti-O-polysaccharide` antibody (NOTE: castenada medium) 4. Mx = `doxycycline + gentamicin`

Answer 121

1. **Leptospirosis** = `leptospiroma interrogans` 2. `rat urine` 3. Mx = **doxycycline** BONUS: **Weil's disease** (presets with AKI + aseptic meningitis)

Answer 122

1. **Lyme disease** = `borrelia burgdorfer`i 2. `Ixodes ticks` 3. Ix = **ELISA** 4. Mx = **doxycycline** NOTE: bull's eye rash (erythema chronicum migrans) is seen in EARLY disease (pt is presenting with late S&S)

Answer 123

* `Yersinia pestis` * RFs = **Yosemite** (reside in rats, spread by `fleas`) * Mx = causes dry gangrene slowly --> `chloramphenicol + doxycycline + gentamicin + streptomycin` NOTE: enlarged LNs called buboes (AKA bubonic plague)

Answer 124

1. **Anthrax** = `bacillus athracis` 2. `Cows` 3. CXR = `mediastinal haemorrhage`; colonoscopy = GI ulcers + perforation 4. Mx = `doxycycline / ciprofloxacin`

Answer 125

1. **Leishmaniasis** (cutaenous = `leishmania major/tropica`) 2. `Sandfly` 3. Ix: NMN (Novy-Macneal-Nicolle); `splenic aspirate` 4. Mx = amphotericin B

Answer 126

* `Tsetse fly` 1. Trypanosoma `brucei` **gambiense** (African) = gradual infection (GG) 2. Trypanosoma `brucei` **rhodesiense** = rapid infection (RR) 3. Trypanosoma `cruzi` = acutely Romana’s sign (purple eyelid); chronically dysphagia due to formation of megaoesophagus and megacolon

Answer 127

* **Cat scratch disease** = `bartonella henselae` * `Cats` * Mx = **doxycycline**

Answer 128

1. Tapeworm from **pork** = `taeniae solium` 2. Tapeworm from **beef** = `taeniae saginata` 3. Tapeworm from **dogs** = `echinococcus granulosus` 4. **Schistomiasis** = `schistosoma haematobium` (flukes) 5. **Ascariasis** = `ascaris lumbricoides` (roundworm) 6. **Hookworm** infection = `ancyclostoma duodenale` (roundworm) 7. **Threadworm** = `enterobius vermicularis` (sounds italian) 8. **Strongyloidiasis** = `strongyloides stercoralis` (roundworm) 9. **Elephantiasis** = `wuchereria bancrofti` (roundworm) 10. **Onchocerciasis** (or river blindness) = `onchocerca volvulus` (roundworm)

Answer 129

1. Tapeworm from **pork** (`taeniae solium`) AND 2. from **beef** (`taeniae saginata`): * Mass lesions in the brain w/ `swiss cheese appearance` * Mx: -bendazoles 3. Tapeworm from **dogs** (`echinococcus granulosus`): * `Liver cysts` * If cyst ruptures, then **anaphylactic like reaction** * Mx = -bendazoles

Answer 130

1. **Flukes** = `schistosoma haematobium` (AKA **schistomiasis**) * `Itchy rash` + painless haematuria * RFs = **swimming** * Katayama fever (fever, rash, myalgia, **hepatosplenomegaly**) * Bladder calcification * `↑ risk of bladder SCC` * Mx: `Praziquantel` (increases permeability towards Ca2+) 2. **Threadworms** = `enterobius vermicularis` * `Perianal itching` especially at night * **Vulval** symptoms in females * Ix = **sticky plastic tape** to perianal area * Mx = `mebendazole` for patient + **family members**

Answer 131

1. **Ascariasis** = `ascaris lumbricoides` * Soil transmitted helminth (giant roundworm) * Intestinal obstruction * Loffler’s syndrome = eosinophilic pneumonia 2. **Hookworm** infection = `ancyclostoma duodenale` * Larvae `penetrate skin of feet` (transdermal) * Causing **GI infections** (which lead to `anaemia` as worms attach to the intestinal wall + feed on blood, causing chronic intestinal blood loss) * Mx = albendazole, me**bendazole** 3. **Strongyloidiasis** = `strongyloides stercoralis` (roundworm) * Diarrhoea + abdominal pain * Papulovesicular lesions where the **skin** has been **penetrated** by infective larvae, larva currens * Mx = `ivermectin` (activated glutamate-gated chloride channels) 4. **Elephantiasis** = `wuchereria bancrofti` * Transmission by `female mosquito` * Causes **blockage of lymphatics** → fluid accumulation + swelling (elephantiasis) * Mx = dietylcarbamazine (inhibits arachidonic acid metabolism) 5. **Onchocerciasis** (or river blindness) = `onchocerca volvulus` * **River blindness **(visual impairment due to ocular lesions + inflammation) + hyperpigmented skin * **Allergic reaction** to microfilaria (AKA **larvae**) * Mx = `IVER`mectin for r`IVER`blindness

Answer 132

swiss cheese

Answer 133

* **Tapeworm** infection = `echinococcus granulosus` * Mx = mebendazole

Answer 134

1. **Schistomiasis** = `schistosoma haematobium` (flukes) 2. Mx = Praziquantel BONUS: ↑ risk of bladder cancer

Answer 135

Loeffler's syndrome

Answer 136

Hookworm --> penetration through the skin

Answer 137

perianal itching Mx = mebendazole for WHOLE household

Answer 138

Penetration through skin

Answer 139

Wuchereria bancrofti Mx = diethylcarbamazine

Answer 140

Ivermectin (cause r`iver` blindness)

Answer 141

**1. Athlete's foot** = `tinea dermatophyte` (ringworm) * Specifically `trichophyton rubrum` causes athlete’s foot * Scaly / peeling / cracked skin between toes * **Mx** = **topical** antifungal e.g. clotrimazole (oral considered if complex e.g. multiple sites of infection or toe nail infection) * NOTE: Potassium hydroxide mixed with nail/skin clippings is a decent diagnostic test for the presence of tinea or trycophyton **2. Tinea capitis** = `tinea dermaphyte` on scalp (scalp ringworm) * Scaly + itchy patches + `well defined patches of hair loss` * Painful, swollen lymph nodes * Mx = **systemic** antifungals (e.g. terbinafine) + anti-fungal shampoos to reduce transmission * NOTE: always order LFTs before starting terbinafine as it is metabolised by the liver **3. Pityriasis versicolor** = malassezia furfur * **Flaky discolouration** (hypopigmentation); asymptomatic * Microscopy = `spaghetti + meatballs` appearance * Wood's Lamp = patches that fluoresce a faint orange colour * Mx = **topical** antifungal e.g. ketoconazole

Answer 142

**1. Candidiasis** = `candida albicans` (yeast) * Deep-seated infections (e.g. `oesophagitis` = **odynophagia**) in the immunocompromised * 'Cottage cheese' like * Ix = **Germ tube test** (for albicans) * Mx = `fluconazole` (or amphotericin B for invasive disease) * NOTE: if non-albicans disease, use caspofungin (type of echinocandin) **2. Cryptococcis** = `cryptococcus neoformans` (yeast) * Found in `pigeon` droppings * Main RF = immunosuppression * Sx = insidious onset **meningitis** in HIV * Ix = `India ink` stain → yeast cells surrounded by halos * Mx = **amphotericin B** **3. Histoplasmosis** = `histoplasma capsulatum` * Found in bird / bat **droppings** * Causes chronic `progressive lung disease` (Sx = cough, chest pain, + fever) * Endemic to the Mississippi River region **4. Aspergillosis** = `aspergillus` * Aspergillus `flavus` = stored grains/peanuts + produces **aflatoxin** that can lead to hepatocellular carcinoma * Ix = **galactomannan** ELISA (part of aspergillus cell wall) * Staining = methenamine silver stain * Mx = `amphotericin B` (longer course than cryptococcus) * Aspergillus **fumigatus** = causes allergic bronchopulmonary aspergillosis, aspergilloma, + invasive aspergillosis in those with `cystic fibrosis` * NOTE: its burkholderia cepecia that is CI for lung transplant in CF pts **5. Mucormycosis** = `rhizopus + mucor` (AKA 'black fungus') * **Black pus** from nose/mouth * Very severe in immunocompromised/poorly controlled diabetes * Sx = cellulitis, `necrotic destructive lesions` around the face e.g. jaw * Mx = `surgical debridement` + **amphotericin B** **6. Onychomycosis** * Thickened nails * Mx = `Nail lacquers / turbinafine` **7. Sporotrichosis** = `sporothrix schnekenii` * Caused by **rose pricks** * RF = rose gardeners * `Painless nodular lesion`, rash + ascending lymphadenopathy * May lead to bone/joint/muscle involvement

Answer 143

`Trichophyton rubrum` BONUS: KOH → mixed with nail/skin clippings can test for presence of tinea or trycophyton

Answer 144

1. **Tinea capitis** 2. Mx = systemic antifungals (e.g. `terbinafine`) + anti-fungal shampoos to reduce transmission BONUS: order **LFTs** before starting terbinafine as it is metabolised in the liver

Answer 145

1. **Pityriasis versicolor** (AKA tinea versicolor) = `malassezia furfur` 2. Topical antifungal e.g. ketoconazole

Answer 146

1. **Candidiasis** = `candida albicans` 2. Ix = **Germ tube test** (for albicans) 3. Mx = `fluconazole`

Answer 147

1. Cryptococcus neoformans 2. Amphotericin B

Answer 148

1. **Histoplasmosis** = `Histoplasma capsulatum` 2. Found in bird/bat droppings → causes chronic progressive lung disease; endemic to Mississippi river

Answer 149

Galactomannan

Answer 150

1. **Aspergilloma** = `aspergillus` 2. If aspergillus flavus → produces **aflatoxin** that can lead to hepatocellular carcinoma (`HCC`)

Answer 151

1. **Mucormycosis** = `rhizopus` and `mucor` 2. **Surgical debridement** (+ amphotericin B)

Answer 152

Onychomycosis

Answer 153

**Sporotrichosis** = `sporothrix schnekenii` NOTE: may also present with ascending lymphadenopathy

Answer 154

**1. -azoles** * Targets `cell membrane synthesis` → inhibits 14α-demethylase which produces **ergosterol** * AEs = P450 inhibition, liver toxicity * Indications = yeast **2. Amphotericin B (polyene)** * Targets `cell membrane integrity` → binds with **ergosterol** forming a transmembrane channel that leads to monovalent ion (K+, Na+, H+ and Cl) leakage * AEs = nephrotoxicity, flu-like symptoms, hypokalaemia, hypomagnaseamia * **Indications** = `systemic fungal infections e.g. cryptococcus, aspergilloma` **3. Terbinafine** * Targets `cell membranes` → inhibits **squalene** **epoxidase** * Indications = oral form used to treat `nail infections` **4. Griseofulvin** * Interacts w/ microtubules to disrupt mitotic spindle * AEs = induces P450 system, teratogenic **5. Flucytosine** * Inhibits `DNA synthesis` → converted by cytosine deaminase to 5-fluorouracil, which inhibits thymidylate synthase and disrupts fungal protein synthesis * AE = vomiting **6. Caspofungin (echinocandin)** * Targets `cell wall` → inhibits synthesis of beta-glucan (fungal cell wall component) * AEs = flushing * Indications = yeast infections (less toxic SEs) **7. Nystatin** * Targets `cell membrane integrity` → binds with **ergosterol** forming a transmembrane channel that leads to monovalent ion (K+, Na+, H+ and Cl) leakage * Due to toxicity, can only be used `topically` (e.g. for oral thrush)

Answer 155

1. **Toxoplasmosis** → `toxoplasma gondii` 2. **Neonatorum opthalmia** → `chlamydia trachomatis / neisseria gonorrhoeae` 3. **Parvovirus** → `parvovirus B19` 4. **Varicella Zoster Virus** → `VZV` (HHV3 is the most common VZV) 5. **Rubella** → `Rubella` 6. **Cytomegalovirus** → `CMV` (HHV5 is the most common CMV) 7. **Herpes Simplex Virus** → `HSV` 8. **HIV** → `HIV` 9. **Syphilis** → `treponema pallidum` 10. Congenital Zika → `zika virus`

Answer 156

* *`Toxoplasma gondii`* * 60% **asymptomatic** at birth (but later develop `low IQ + deafness`) * 40% **symptomatic** → cerebral calcification triad = `seizures, hydrocephalus, chorioretinitis` (+ cataracts) * NOTE: Seize (seizures) High (hydrocephalus) Colours (chorioretinitis) * Mx = pyrimethamine

Answer 157

* *`Chlamydia trachomatis / Neisseria gonorrhoeae`* * `Newborn conjunctivitis` → **same-day ophthalmology assessment**

Answer 158

* *`Parvovirus B19`* * Can **cross the placenta** in pregnant women * Causes severe **anaemia** and consequent **heart failure** in the `foetus`, leading to `hydrops fetalis` (ascites, pleural +/- pericardial effusions) * Ix = maternal serology to check for IgM against parvovirus B19; PCR to detect parvovirus B19 DNA * Mx = regular monitoring for complications

Answer 159

* *`Varicella Zoster Virus`* (most common = **human herpes virus 3**) * Congenital varicella syndrome only occurs if mother infected within `20 weeks gestation` * `I`nfections `C`an `C`ause `M`any `L`ifelong `C`omplications * `I`**UGR** (Intrauterine Growth Restriction) * `C`**ataracts** * `C`horioretinitis * `M`icrocephaly * `L`**imb hypoplasia** * `C`utaneous scarring * NOTE: maternal infection during time of delivery can lead to severe, disseminated infection in the newborn * Mx = check maternal IgG antibody to varicella zoster → if negative, `oral aciclovir`

Answer 160

* *`Rubella virus`* * **RARE** due to MMR vaccine * Triad = `c`**ataracts**, `p`**atent ductus arteriosus**, `s`**ensorineural deafness** * NOTE: mnemonic for triad = `C`hild `P`rotective `S`ervices * Most common in `first trimester`, **low risk after 20 weeks** * Ix = maternal IgM + IgG serology; PCR for rubella virus RNA * Mx = supportive

Answer 161

* *`Cytomegalovirus`* (human herpes virus 5 = most common) * `G`reat `M`others `P`rotect `E`very `H`alf `S`ibling * `G`**rowth retardation** * `M`**icrocephaly** * Pinpoint `p`**etechial** 'blueberry muffin' skin lesions * `E`**ncephalitis** (seizures) * `H`**epatosplenomegaly** * `S`ensorineural **deafness** * NOTE: complications in the baby are uncommon if infection occurs beyond 20 weeks’ gestation * Histology = “`Owl’s eye`” appearance → intranuclear inclusion bodies * **Mx** = `ganciclovir`

Answer 162

* *`Herpes simplex virus`* * Most likely transmitted to neonate in the **third trimester** * 3 forms of neonatal herpes simplex infection: * **Localised** to `SEM` (skin, eye, and mouth) disease causing a `blistering rash` * **Localised** to `CNS` causing `meningoencephalitis` * `Disseminated` infection casuing **multiple organ involvement** * Mx = IV aciclovir

Answer 163

* *`Human immunodeficiency virus`* * ↑ risk of intrauterine transmission from HIV-positive mother to child * Newborn with **HIV** = failure to thrive, developmental delay, `recurrent / opportunistic infections`, **progressive encephalopathy** * **Mx** = `ART (zidovudine)` for **mother** to get viral load < 50 HIV RNA copies/mL at 36 weeks' gestation; `neonatal ART prophylaxis` should be commenced within 4 hours after birth + given for 4 weeks * NOTE: maternal viral load is the most predictive factor for perinatal HIV transmission

Answer 164

* *`Treponema pallidum`* * Mnemonic: `S`yphilis `R`eally `H`as `U`gly `H`idden `M`arkers * `S`addle-rash deformity * `R`ash on hands and soles * `H`epatosplenomegaly * `U`**nilateral enlargement of clavicle** * `H`**utchinson’s teeth** * `M`**ulberry molars** * Ix = syphilis screening assay

Answer 165

* *`Zika virus`* (enveloped flavivirus) * **Severe microcephaly + skull deformity** * Secreased brain tissue, subcortical calcification * Retinopathy + deafness * Talipes (feet turned in like club foot) * Hypertonia

Answer 166

Neonatal = < 6 weeks old **Early onset sepsis = `< 48hrs` after birth** * Pathogens = `Group B streptococcus`, E. coli, Listeria monocytogenes * Maternal Sx = (P)PROM, fever, foetal distress * **Neonatal Sx** = respiratory distress, acidosis, fever, clinically unwell * Ix = `SEPTIC SCREEN` (FBC, CRP, blood culture, ABG, urinalysis, LP, CXR) * Mx = `Benzyl penicillin + gentamicin + amoxicillin/ampicillin` (for listeria cover) **Late onset sepsis = `> 48hrs` after birth** * Pathogens = **Coagulase -ve staph** (e.g. epidermidis, haemolyticus, saphrophyticus), Group B streptococcus, E. coli, Listeria monocytogenes * **Neonatal Sx** = bradycardia, apnoea, poor feeding, irritability * Ix = `SEPTIC SCREEN` (FBC, CRP, blood culture, ABG, urinalysis, LP, CXR) * **Mx** = `benzylpenicillin + gentamicin` (2nd line: Tazocin + vancomycin) * Mx for late onset from community = amoxicillin + cefotaxime

Answer 167

1. > 3 months of age = **neisseria meningitidies** (non-blanching petechial rash AKA meningococcal septicicaemia) 2. < 2 years old = **streptococcus pneumoniae** 3. < 3 months old + unvaccinated = **haemophilus influenzae** 4. 1-3 months old = **GBS** / E.coli / listeria

Answer 168

TRIAD = `s`**eizures**, `h`**ydrocephalus**, `c`**horioretinitis** Mnemonic = Seize (seizures) High (hydrocephalus) Colours (chorioretinitis) (still waiting for a better one sigh)

Answer 169

Neisseria gonorrhoea or chlamydia trachomatis

Answer 170

`Hydrops fetalis` (effusions + ascites)

Answer 171

`I`nfections `C`an `C`ause `M`any `L`ifelong `C`omplications * `I`**UGR** (Intrauterine Growth Restriction) * `C`**ataracts** * `C`horioretinitis * `M`icrocephaly * `L`**imb hypoplasia** * `C`**utaneous scarring**

Answer 172

`C`hild `P`rotective `S`ervices * `C`**ataracts** * `P`**DA** (patent ductus arteriosus) * `S`ensorineural **deafness**

Answer 173

`Cytomegalovirus (CMV)` NOTE: `G`reat `M`others `P`rotect `E`very `H`alf Sibling * Growth retardation * **Microcephaly** * Pinpoint **petechial** ‘blueberry muffin’ skin lesions * Encephalitis (seizures) * **Hepatosplenomegaly** * Sensorineural deafness * Histology = “`Owl’s eye`” appearance → intranuclear inclusion bodies

Answer 174

Neonatal herpes simplex infection - characterised by vesicles and pustules involving the face + mouth **Neonatal herpes simplex** infection can manifest in **3 forms**: localised to the skin, eyes and mouth (`SEM`), localised to the central nervous system (i.e. `encephalitis`) and `disseminated` infection.

Answer 175

Hutchinson’s teeth Mulberry molars

Answer 176

Zika virus

Answer 177

1. **Herpesviridae** (may cause latent infections): `CMV, EBV, HSV, HHV6, HHV8, VZV` 2. **Polyomaviridae**: `JC` (John Cunningham) virus (leads to PML if given mycophenolate mofetil) + `BK` (Human polyomavirus 1) virus 3. **Respiratory viruses**: `influenza` A + B, `parainfluenzae`, Respiratory Syncytial Virus (`RSV`), `adenovirus, coronavirus` 4. **Hepatitis** **viruses**: `A` (normally vaccinate prior to immunosuppression), `B`, `C`, `D`, `E` BONUS: `4 D's` = `D`issemination, `D`ifferent organs, `D`isastrous severity, `D`ysplasia

Answer 178

* `Parvovirus` = DNA virus that is single stranded * `Reoviridae` (e.g. **rotavius**) = RNA virus that is double stranded NOTE: RNA viruses can be +ve sense or -ve sense → +ve sense means the RNA can be directly translated, whereas -ve sense means the RNA cannot be directly translated

Answer 179

**1. CMV** * Enveloped, **dsDNA** genome * Lies latent in monocytes + dendritic cells * CMV cells = "`owls eye`" (inclusion bodies) * Sx in immunocompromised (affects esp. **transplant patients**) = encephalitis, retinitis, pneumonitis, colitis, marrow suppression, **oesophagitis (`LINEAR` ulcers)** * **Mx** = IV `Ganciclovir` / PO valganciclovir (1st line); IV Foscarnet (2nd line) **2. EBV** * Enveloped, **dsDNA** genome * Lies latent in B cells * `NOTE: EBV not dangerous in pregnancy!` * Glandular fever = **TRIAD** of `fever, pharyngitis, lymphadenopathy` * Ix = blood film (**atypical lymphocytes** peripherally - stretched out cytoplasm), EBV serology * **Monospot agglutination** (AKA heterophile antibody test AKA Paul-Bennell test) = diagnostic * Mx = supportive * Mx w/ **penicillins** in glandular fever may provoke a `morbilliform eruption` (widespread maculopapular rash) * As EBV can lie dormant in B-cells, it `predisposes to Burkitt’s lymphoma` * **Post-transplant** Lymphoproliferative Disease (PTLD) in **immunocompromised** Patients → Mx w/ `Rituximab` (anti-CD20 monoclonal Ab) * Mnemonic: `BBB` → E`B`V, resides in `B` cells, predisposes to `B`urkitt's lymphoma **3. HSV** * Enveloped, **dsDNA** genome * Lies latent in sensory neurons * `HSV-1` → herpes **labialis** (**cold sores**) = severe painful ulceration, erythematous base +/- fever + submandibular lymphadenopathy * Differential – Herpangina (Coxsackie A) * `HSV-2` → **genital** ulceration = fever, dysuria, malaise, Inguinal lymphadenopathy, pain, + vesicular rash * HSV-2 may cause **sacral radiculomyelitis** → urinary retention (self limiting) * NOTE: HSV-1 more likely to cause encephalitis, whereas HSV2 is more likely to cause meningitis * Sx in immunocompromised: cutaneous **dissemination**, **oesophagitis** causing odynophagia (`CIRCULAR` **ulcers**), hepatitis, viraemia, **herpetic whitlow** (HSV skin infection) * Mx = `aciclovir` (or valaciclovir, 'val' meaning ucreased bioavailability to take orally) **4. HHV6** * AKA **roseola** virus * Latent in monocytes / lymphocytes * Roseola infantum ( = exanthum subitum, Sixth disease) → **FEVER then** sudden appearance of a maculopapular **rash** (starts on `trunk` + spreads to face / extremities) * Most common cause of `febrile convulsions` * Transmits via droplet infection * Supportive Mx **5. HHV8** * AKA Kaposi's sarcoma * Enveloped, **dsDNA** genome * Genital transmission * **Kaposi's sarcoma** seen in immunocompromised, esp. due to `HIV` * Mx = chemoradiotherapy + surgical excision + HAART for underlying HIV * If HHV8 associated with **EBV co-infection** → primary effusion `lymphoma` **6. VZV** * Enveloped, **dsDNA** genome * Lies latent in `sensory` neurons; hence dermatomal distribution when it is reactivated * Chickenpox Sx = fever + headache followed by **itchy rash** * Eye involvement = `opthalmic herpes zoster` * **Facial palsy** (unilateral facial drooping) + vesicles in **ear** = `Ramsay hunt syndrome` * Shingles (reactivation) RFs = older, stress, ↓ immunity * Shingles Sx = painful rash in specific **dermatome** * In immunocompromised, more likely to cause `retinal necrosis + multidermatomal shingles` * Mx w/ `aciclovir` if adult / immunocompromised neonate / eye involvement

Answer 180

**1. JC (John Cunningham) virus** * Unenveloped, **dsDNA** genome * In immunocompromised (especially AIDS): Progressive multifocal leukoencephalopathy (`PML`) + rapidly `demyelinating disease` (+ neurological deficits) * Mx = HAART for HIV **2. BK (Human polyomavirus 1) virus** * Unenveloped, **dsDNA** genome * In immunocompromised (esp. **transplant**): BK haemorrhagic cystitis + `BK nephropathy` (as it lies dormant in kidneys) * Mx = **Cidofovir**

Answer 181

**1. Influenzae virus** * Enveloped, negative sense segmented genome (8 segments) * Antigenic `DRIFT` = point mutations * Antigenic `SHIFT` = segments rearrange (can cause pandemics) * Sx = URTI + systemic features include muscle aches * **Haemagglutinin** activity = binds to sialic receptors + allows for virus **ENTRY** * **Neuraminidase** activity = cleaves sialic acid + allows for **EXIT** of virions from host cell * Mx = oral `oseltamivir` (neuraminidase inhibitor) - AKA Tamiflu * Other Mx = polymerase inhibitor (e.g. Baloxavir) **2. Adenovirus** * Unenveloped, dsDNA genome * In immunocompromised (especially transplant): encephalitis, **pneumonitis**, colitis, haemorrhagic cystitis * **Supportive** Mx, unless multi-organ involvement, then Cidofovir +/- IVIG **3. Coronavirus** * **Positive sense ssRNA** genomes * URTI +/- systemic symptoms e.g. myalgia * Severe infections can cause ARDS, respiratory failure, shock, multiple organ dysfunction * Mx = supportive OR **dexamethasone + remdesivir** if severe

Answer 182

**1. Hepatitis A** * Unenveloped picornavirus, **positive sense ssRNA** genome * **Acute** infection * **Faeco-oral** transmission * Acute hepatitis = 2-6 weeks incubation, severe in elderly * Ix = `anti-HAV IgM` in acute infection (IgM persists up to 14wks) * Mx = supportive; Hep A vaccine available **2. Hepatitis B** * Enveloped hepadnavirus (reversivirus); hybrid genome, mostly DNA * Transmission via **bodily fluids** i.e. sexual, vertical, blood products * Acute (90% resolve in >5 y/o) or chronic * HBV at risk of `reactivation` in **immunocompromised** e.g. Rituximab * **HBV serology** * `HbsAg` (surface antigen) = present in acute or chronic infection, but negative in previous or vaccinated * Anti-HBs (hep B surface antibody) = negative in acute or chronic infection, but positive in previous or vaccinated * *NOTE: vaccine does NOT have core antigen!* * So to differentiate between vaccine vs previous infection → vaccine does not have `anti-HBc IgG` but if previously infected, you would * To differentiate between acute vs chronic infection → `anti-HBc IgM` in acute and anti-HBc IgG in chronic * **HBe = infectivity** * Mx = interferon alpha, lamivudine (nucleoside analogue), entecavir (nucleoside analogue), telbivudine (nucleoside analogue), tenofovir (nucleoTide analogue) **3. Hepatitis C** * Enveloped flavivirus, positive sense ssRNA genome * Mainly a chronic disease (acute less common) - hep `C` for `C`**hronic** * **Blood** borne = infected needles, blood transfusions etc. * `C`omplications = `c`irrhosis, cryoglobulinaemia, glomerulonephritis * Measure **HCV RNA** to confirm infection and assess treatment response (anti-HCV Ab develops after acute infection) * Mx = Peg INF alpha * Curative Mx = NS3/4 protease inhibitors (-previrs, block translation e.g. telaprevir, boceprevir) + NS5A inhibitors (-asvirs, block release e.g. ledipasvir, daclatasvir) + direct polymerase inhibitors (-buvirs, block replication e.g. sofosbuvir, dasabuvir) **4. Hepatitis D** * Deltavirus, enveloped virus, negative sense, single-stranded circular RNA * **Can only infect those with Hep B** * Transmission = sexual, perinatal * May be a **coinfection** (simultaneously) with Hep B OR **superinfection** (on top of chronic) Hep B (`more severe` – often leads to cirrhosis within 2-3yrs) * Mx = Peg INF alpha **5. Hepatitis E** * Unenveloped **positive sense ssRNA** genome * **Acute** infection * **Faeco-oral** transmission * RFs = India * Rare complications: CNS disease e.g. Bell’s palsy, Guillain Barre, other neuropathy * Mx = supportive

Answer 183

**1. CD4+ < 500** * **EBV** (hairy leukoplakia) * `HHV-8` (Kaposi sarcoma) * **HPV** (SCC) * **Candida** (thrush) **2. CD4+ < 200 (NOTE: this is considered AIDS)** * `JC virus` (reactivation = **progressive multifocal leukoencephalopathy**) * `Pnuemocystitic jeroveci` (**pneumonia**) * Histoplasma capsulatum (systemic Sx) **3. CD4+ < 100** * Bartonella **henselae** (cat scratch disease) * Nontuberculous mycobacteria (lymphadenitis) * **CMV** (colitis, `retinitis`, oesophagitis) * `Aspergillus` (haemoptysis, pain, fever) * `Candida` (oesophagitis) * `Cryptococcus neoformans` (meningitis) * `Cryptosporidium parvum` (severe non-bloody darrhoea; Kinyoun acid fast stain) * **Toxoplasma** (brain abscess)

Answer 184

**1. Cystic fibrosis** * `Aspergillus` fumigatus * `Burkholderia` cepecia (CI for lung transplant) * Pseudomonas aeruginosa * Mycobacterium abscessus **2. Sickle cell disease** * `Salmonella` typhi (osteomyelitis) **3. Splenectomy** * `NHS` = neisseria meningitides, haemophilus influenzae, streptococcus pneumoniae

Answer 185

**1. HIV structure** * 2 copies of a `ssRNA` genome within a conical capsid of p24 (which is surrounded by a matrix of viral protein p17) * Viral envelope contains glycoproteins **gp120** and **gp41** * `Pol gene` encodes for reverse transcriptase, integrase and HIV protease **2. HIV entry** * HIV can infect **CD4 T cells, macrophages and dendritic cells** * Gp120 binds to CD4 and `CXCR4` on T cells and CD4 and `CCR5` on macrophages * NOTE: mutations in CCR5 can give immunity to HIV **3. HIV Sx / antibodies** * Sx = glandular fever-like illness * Ix = HIV antibodies using **ELISA** first, confirmed by `Western Blot` * **p24** antigen positive from 1 week to 3-4 weeks after infection * Standard Ix for diagnosis = combination of antibodies + p24 antigen **4. Management** * 2 NRTIs + 1 NNRTI / PI * **Entry inhibitors** e.g. maraviroc (binds to CCR5) or enfuvirtide (binds to gp41) * Nucleoside analogue reverse transcriptase inhibitor (**NRTI**) e.g. `zidovudine` (SE = anaemia), `tenofovir` (recommended NRTI) * NOTE: SEs of NRTIs = peripheral neuropathy, black nails * Non-nucleoside reverse transcriptase inhibitors (**NNRTI**) e.g. `nevirapine` (P450 enzyme inducer) * **Protease inhibitors** (`-navir`) e.g. ritonavir (potent inducer of P450 system) * **Integrase inhibitors** (`-gravir`) e.g. raltegravir (blocks integrase, the enzyme that inserts viral genome into DNA of host cell)

Answer 186

`HHV-8 (Kaposi sarcoma)` = a type of cancer that forms in the lining of blood vessels and lymph vessels Sx = **reddish purple skin lesions**, in the lungs can cause **SOB + haemoptysis** Mx = `radiotherapy and resection`

Answer 187

`CMV retinitis` Mx = **IV ganciclovir** (1st line)

Answer 188

`CMV` (affects esp. `transplant patients`) Sx in immunocompromised = encephalitis, retinitis, pneumonitis, colitis, marrow suppression, **oesophagitis** (`LINEAR` ulcers)

Answer 189

`EBV` Ix for EBV: * **Blood film** = `atypical lymphocytes peripherally` - stretched out cytoplasm * EBV **serology** * Monospot agglutination (AKA **heterophile antibody test** AKA Paul-Bennell test) = diagnostic

Answer 190

**TRIAD** of `fever + pharyngitis + lymphadenopathy` BONUS: `morbilliform eruption` (widespread maculopapular rash) BONUS 2: As EBV can lie dormant in B-cells, it predisposes to `Burkitt’s lymphoma` Mnemonic: `BBB` → E`B`V, resides in `B` cells, predisposes to `B`urkitt’s lymphoma

Answer 191

**HSV-2** (causes genital ulcers) Mx = `aciclovir` BONUS: in the immunocompromised it can cause **oesophagitis** with `CIRCULAR` ulcers (unlike CMV which causes linear ulcers) NOTE: HPV genital warts are usually painless, without ulceration

Answer 192

**Shingles** (`VZV`) Mx = `aciclovir` Complications: * Eye involvement = `opthalmic herpes zoster` * Facial palsy (unilateral facial drooping) + vesicles in ear = `Ramsay hunt syndrome`

Answer 193

`Progressive multifocal leukoencephalopathy (PML)` no specific Mx for JC virus → supportive care + optimal HAART for HIV

Answer 194

Lies dormant in the kidneys → `BK nephropathy` Mx = **Cidofovir** NOTE: BK virus = human polyomavirus

Answer 195

Oseltamivir (neuraminidase inhibitor)

Answer 196

Hepatitis `C` (for `c`hronic) Spread via infected blood e.g. sharing needles, blood transfusions

Answer 197

`Acute infection + high infectivity` HBsAg +ve = current infection Anti-HBc `IgM` +ve and IgG -ve = acute infection Anti-HBe +ve = high infectivity

Answer 198

``` Hep A + E faeco-oral ```

Answer 199

Bell’s palsy, Guillain Barre

Answer 200

Mutations in CCR5 can give immunity to HIV NOTE: HIV infects macrophages via CCR5

Answer 201

* Pol gene * ELISA Anti-HIV antibodies = screening (NB: unreliable in babies as IgGs maybe passed vertically) * Western Blot = confirmatory (15-45 days since infection) * Viral load using PCR = very sensitive * Flow cytometry for CD4 count (< 200 = AIDS) * ART resistance assays

Answer 202

* **HAART** = 3+ ART drugs needed * Usually: `2 NRTIs + 1x NNRTI OR boosted PI` * Indications for immediate HAART = SYMPTOMATIC, CD4+ < 200 cells/ul, consider if CD4 between 200 and 350 Nucleoside reverse transcriptase inhibitors (**NRTI**) e.g. Zidovudine/Abacavir (OR nucleo`t`ide RTI e.g. `tenofovir`) **NNRTI** e.g. `efavirenz` Boosted **PI** e.g. `ritonavir` 2nd line = integrase inhibitors (-gravir) 2nd line = entry / attachment inhibitors (e.g. maraviroc) 2nd line = fusion inhibitors (e.g. enfuvirtide)

Answer 203

Due to efavirenz being a P450 inducer

Answer 204

**1. Aciclovir** * `Guanosine` analogue, phosphorylated by thymidine kinase * Inhibits the **viral** `DNA polymerase` * Used to Mx `HSV, VZV` * **AE = crystalline nephropathy** **2. Ganciclovir** * `G`uanosine analogue, phosphorylated by thymidine kinase Inhibits the **viral** `DNA polymerase` * Used to Tx `CMV` * AE = myelosuppression / agranulocytosis **3. Ribavirin** * `Guanosine` analogue that inhibits inosine monophosphate (IMP) dehydrogenase → interferes with the capping of viral mRNA * Used to Tx chronic `hepatitis C`, `RSV` * AE = haemolytic anaemia **4. Amantadine** * Inhibits uncoating (M2 protein) of virus in cells * Also releases dopamine from nerve endings * Used to Tx Parkinson's, influenza * AEs = confusion, ataxia, slurred speech **5. Oseltamivir** * Inhibits **neuraminidase** * Used to Tx `Influenza` **6. Foscarnet** * Pyrophosphate analogue which inhibits viral DNA polymerase * Used to Tx `CMV, HSV` if not responding to aciclovir * AEs = nephrotoxicity, hypocalcaemia, hypomagnasaemia, seizures **7. Interferon-α** * Human glycoproteins that inhibit synthesis of mRNA * Used to Tx `chronic hepatitis B & C, hairy cell leukaemia` * AEs = flu-like symptoms, anorexia, myelosuppression **8. Cidofovir** * Acyclic nucleoside phosphonate * NOTE: it is therefore independent of phosphorylation by viral enzymes (compare and contrast with aciclovir/ganciclovir) * Used to Tx `CMV retinitis in HIV` * AE = nephrotoxicity

Answer 205

Cidofovir (or ganciclovir)

Answer 206

1. **Cocci** `Catalase +ve` = **staphylococcus** * **Co-agulase +ve** = staphylococcus `aureus` * **Co-agulase -ve** = staphylococcus `saprophyticus`, `epidermidis` `Catalase -ve` = **streptococcus** → blood agar * **Alpha haemolytic** (PARTIAL haemolysis - green agar) = streptococcus `pneumoniae` (optochin sensitive), streptococcus `viridans` (optochin resistant) * **Beta haemolytic** (COMPLETE haemolysis) = streptococcis `pyogenes` (GAS, bactracin sensitive), streptococcus `agalactaei` (GBS, bacitracin resistant) * **Gamma haemolytic** (NO haemolysis) = `enterococcus` 2. **Rods** * `A`ctinomyles * `B`acillus cereus * `C`lostridium * `D`iphtheria * `L`isteria monocytogenes

Answer 207

**Growth on MacConkey Agar = YES** `Lactose fermenter` on MacConkey Agar * **Indole test +ve** = `Escherichia coli` * **Indole test -ve** = `Klebsiella pneumoniae` `Non-Lactose fermenter` on MacConkey Agar * **Oxidase +ve** = `pseudomonas, vibrio` * **Oxidase -ve** = `salmonella, shigella, yersinia, proteus mirabilis` **Growth on MacConkey Agar = NO** * **Growth on Blood Agar** = `brucella`, `eikenella` (human bite), `pasteurella` (dog bite) * **No growth on Blood Agar** = `haemophilus`

Answer 208

**Cocci:** * Neisseria meningitides, gonorrhoea * Moraxella cararrhalis **Coccobacilli:** * Haemophilus influenzae, ducreyi * Bordetella pertussis * Pseudomonas aeruginosa * Chlamydia trochamatis **Rods:** * Enterobacteriacaea * Escherichia coli * Salmonella * Shigella * Klabsiella * Yersinia **Spirochaetes:** * Treponema pallidum * Leptospirosis * Borrelia

Answer 209

**Bacteria:** * Chlamydia trochamatis * Rickettsia * Coxiella (Q fever) * Mycobacteria laprae **Protozoa:** * Toxoplasma * Cryptosporidium * Leishmania **Fungi:** * Pneumocystitis jeroveci

Answer 210

**1. Penicillins (-cillin)** * E.g. `amoxicillin`, `piperacillin` (against pseudomonas) * **Broad** spectrum * Inhibits `transpeptidase`, the enzyme that forms crosslinks during cell wall formation * Indications = pneumonia, acute otitis media, susceptible infections * **SEs = GI** (e.g. diarrhoea/vomiting), Morbiliform rash (if given in EBV) **2. Carbapenems (-penem)** * E.g. `ertapenem, meropenem` * **Broad** spectrum * Inhibits `transpeptidase`, the enzyme that forms crosslinks during cell wall formation * Indications = HAIs * SEs = injection site reactions, GI ( e.g. diarrhoea/vomiting) **3. Cephalosporins** * E.g. `ceftriaxone, cefalexin` * **Broad** spectrum * Inhibits `transpeptidase`, the enzyme that forms crosslinks during cell wall formation * Indications = meningitis * SEs = Low toxicity but GI disturbances common

Answer 211

1. `T`**etracyclines (-cycline)** * E.g. `doxycycline, lymecycline` * **Broad** spectrum * Bind to the `30S` subunit of ribosomes * Indications = mycoplasma, rosacea, acne, lyme disease * AEs = **Teratogenic** + light-sensitive rash, **contraindicated in < 12 y/o** due to teeth discolouration 1. `A`**minoglycosides ** * E.g. `gentamicin, amikacin` * Gram **-ve** and/or anaerobes * Bind to `30S` ribosomal subunit, preventing elongation of polypeptide chain * Indications = meningitis, endocarditis, acute pyelonephritis, catheter-associated UTI * SEs = **ototoxic + nephrotoxic** 1. `M`**acrolides (-mycin)** * E.g. `azithromycin, clarithromycin` * Gram **-ve** * Bind to the `50S` subunit of ribosomes * Indications = mild staph/strep infection `if allergic to penicillin`, specifically useful against **Campylobacter + Legionella** * SEs = nausea (especially erythromycin), P450 inhibitor, **prolonged QT interval** 1. `C`**hloramphenicol** * Potent broad-spectrum antibiotic * Indications = conjunctivitis, plague (Causes dry gangrene slowly) 1. `O`**xazolidinones (-zolid)** * E.g. Linezolid * Binds to the `23S` portion of the `50S` ribosome subunit to prevent `70S` subunit formation * Indications = highly active against **gram +ve** organisms - especially MRSA and VRE * SEs = thrombocytopaenia + neurological side effects

Answer 212

**1. Glycopeptide** * E.g. `vancomycin, teicoplanin` * Gram **+ve** * inhibits cell wall formation by binding to D-Ala-D-Ala moieties, preventing polymerisation of peptidoglycans * Indications = **MRSA** infection * SEs = **Nephrotoxic**; `Red man syndrome` (on rapid infusion) **2. Nitroimidazoles (-dazole)** * E.g. `metronidazole, tinidazole` * Anaerobes + Protozoa * Under anaerobic conditions, an active intermediate is produced which causes DNA strand breakage * Indication = **anaerobic** infections, **H.pylori** eradication, **BV / TV, PID** * SEs = dry mouth, myalgia and nausea; disulfiram reaction w/alcohol **3. Fluoroquinolone (-floxacin)** * E.g. `levofloxacin, ciprofloxacin` * **Broad** spectrum * Act on alpha subunit of DNA gyrase * Indication = UTI, pneumonia, bacterial gastroenteritis, neutropenic sepsis prophylaxis * SEs = GI disturbances (C.difficile infection), CNS disturbances **4. Sulfonamides (-xazole)** * `Sulfamethoxazole` (component of co-trimoxazole) * **Broad** spectrum * Inhibiting dihydropteroate synthetase * Indications = **pneumocystis jirovecii** (co-trimoxazole) * SEs = hyperkalaemia, headache, SJS rash

Answer 213

1. `T`etracyclines (-cycline) = 30S 1. `A`minoglycosides = 30S 1. `M`acrolides (-mycin) = 50S 1. `C`hloramphenicol = 50S 1. `O`xazolidinones (-zolid) = 23S + 50S → 70S

Answer 214

Penicillins e.g. amoxicillin

Answer 215

Vancomycin

Answer 216

Piperacillin (+ tazobactam)

Answer 217

Doxycycline

Answer 218

Metronidazole (Dx = TV)

Answer 219

1. **Skin** → *S. aureus* → `flucloxacillin` 2. Pharyngitis → beta-haemolytic strep → `benzylpenicillin` 3. **CAP** → mild = `amoxicillin`; moderate = `amoxicllin + clarithromycin` 4. H****AP → severe = `co-amoxiclav + clarithromycin` 5. **Bacterial meningitis** → *meningococcus / streptococcus* → `Ceftriaxone` (+ amox/ampicillin for young/old for listeria cover) 6. **UTI** → community → `trimethoprim / nitrofurantoin` (if HAI = co-amoxiclav or cephalexin) 7. **Sepsis** → severe → `tazocin / ceftriaxone, metronidazole + gentamicin` (if neutropenic then tazocin + gentamicin) 8. **Colitis** → *C. diff* → `metronidazole` or `vancomycin`

Answer 220

**1. Giemsa** * Nuclei stain purple, cytoplasm stain blue to pale pink, eosinophils stain orange * `Trypanosomes` (e.g. Trypanosoma brucei, Trypanosoma cruzi, `Leishmania` spp) * `Chlamydia` * Cytomegalovirus (`owl-eye` viral inclusions) **2. India ink** * `Cryptocccus neoformans` (**halo** sign) **3. Periodic acid-Schiff stain** * `Candida` * Tropheryma whippelii (AKA **Whipple's disease**) shows deposition of macrophages **4. Silver stain** * Pneumocystis jiroveci * Legionella pneumophilia * Helicobacter pylori * Aspergillus * HIV * NOTE: the **methenamine silver stain** is used for FUNGI e.g. `pneumocystitis, candida, aspergillus` **5. Ziehl-Neelsen** * `Acid fast bacilli` turn `red`, if not, stain remains blue * Mycobacterium `tuberculosis` * `Cryptosporidium` spp. **6. Auramine-Rhodamine** * `Mycobacterium` = `red/yellow` * Not as specific as ZN stain, but more affordable and more sensitive **7. Kinyoun Acid Fast** * AKA modified ZN test * `Cryptosporidium parvum` (causes diarrhoea in immunocompromised) **8. Field’s stain** * Stain is made up of Methylene blue + Eosin Y * `Plasmodium` (thick blood films)

Answer 221

NOTE: `gold standard` for **fungal infections** is `culture`, however, takes many weeks to grow so these tests can be done in the mean time: **1. Tinea / trychophyton** = `KOH` mixed with nail clippings **2. Cryptococcus** = `India` ink stain, `glucuronoxylomannan` antigen test **3. Pneumocystitis** = `periodic acid-schiff (PAS)` stain or silver stain, `beta-D-glucan` antigen test **4. Candida** = methenamine `silver stain` or `PAS`, `beta-D-glucan` antigen test **5. Aspergillus** = methenamine `silver stain` or `PAS`, `galactomannan` antigen test **6. Histoplasmosis** = fungal serology

Answer 222

1. **CMV** 2. **Tinea** / trychophyton 3. **Mycobacterium** tuberculosis 4. **Cryptosporidium** parvum 5. **Mycobacterium** tuberculosis 6. **Plasmodium** (thick film) 7. Pneumocystitis, candida, aspergillus 8. **Candida**, pneumocystitis, aspergillus, whipple's disease 9. **Cryptococcus** neoformans 10. Pneumocystitis, candida 11. Aspergillus 12. Cryptococcus

Answer 223

**1. Buffered charcoal yeast extract** = `legionella` pneumophila **2. Bordet-Gengou** (potato) agar = `bordetella` pertussis **3. Eaton** agar = `mycoplasma` pmeumoniae **4. Chocolate** agar = `haemophilus` influenzae, haemophilus ducreyi **5. Thayer Martin** media (chocolate agar variant) = `neisseria` meningitidis, neisseria gonorrhoeae **NOTE**: for thayer-martin, add vancomycin (inhibits Gram positives) + polymyxin (inhibits gram negatives) + nystatin (inhibits fungi) **6. Castaneda** medium = `brucellosis` **7. Lowenstein Jensen** media = mycobacterium species → brown coffee coloured (buff), bread-crumb like (rough), sticks to bottom of growth plate (tough) = `Mycobacterium tuberculosis` **8. Blood agar** = alpha haemolytic (green agar - partial) = `streptococcus` pneumoniae + viridans; beta haemolytic (pale agar - partial) = GAS, GBS **9. MacConkey** agar = `pink` with lactose fermenters e.g. `E.coli, Klebsiella, Enterobacter` **10. Czapek dox** agar = `aspergillus` **11. Novy-Macneal-Nicolle** medium = `leishmania` **12. Sabouraud** agar = `fungi` 13. Tellurite agar or **Loeffler's** media = corynebacterium `diptheriae`