Infectious diseases Flashcards
(13 cards)
Sepsis:
- Definition
- Septic shock definition
- Pathophysiology
- Risk factors (6)
- Signs of severe sepsis
- Investigations
- Management
Sepsis:
- Definition: life threatening organ dysfunction due to dysregulated host response to infection
- Septic shock definition: when bp <90 or lactate >4 leading to hypoperfusion
- Pathophysiology: release of cytokines leads to vasodilation + inc cell wall perm leaking to fluid leakage and activation of coag system causing dic
- Risk factors (6): age, comorbs, immunosupp, preg, recent surgery
- Signs of severe sepsis: oligouria, aki, hypotension, lactate >2
- Investigations: qsofa: rr>22, confused, bp <100 - >2 means inc risk
- Management: meropenem
Malaria:
- Definition
- Causative organisms
- Life cycle
- Symptoms
- Signs
- Features of severe falciparum
- Investigations
- Management + prevention
- Complications
Malaria:
- Definition: blood parasite protozoa transmitted by f anopheles mosquitoes
- Causative organisms: plasmodium falciparum (4 weeks inc period, most severe + common), vivax, ovale, malarie (all rest up to 1 year) - minimum period for all is 6 days
- Life cycle: infected blood sucked up by mosquitoes - produces sporozites which is then injected into other human. sporozites to liver and mature to schizocytes -> merocytes then burst out of liver and infect rbcs which then rupture (hemolytic anaemia) as they reproduce and develop into gametocytes which are then ingested by another mosquito
- Symptoms: abrupt onset rigors + high fever cyclical, malaise, headache, myalgia, abdo pain, n+v, diarrhoea
- Signs: pallor, jaundice, hepatosplenomeg, seizures
- Features of severe falcip: schizonts on film, hypoglyc, acidosis, temp >39, severe anaemia, parasite >22%
- Investigations: 3x blood films over 3 days (trophozoites of plasmodium falcip), fbc (anaemia, dec wcc, dec platelets), u+es, lfts (abnorm), glucose, coag, cxr, ct head
- Management + prevention: iv artesunate, if others chlorquine + primaquine (screen for g6pd def before). Prevent via bite repellant, chemoprophylaxis (malarone)
- Complications: cerebral malaria, ards, hypoglycemia, renal failure, pul oedema, dic
Typhoid fever/enteric fever:
- Definition
- Symptoms
- Signs
- Investigations
- Management
- Complications
Typhoid fever:
- Definition: salmonella typhi gram - bacilli (if paratyphoid then salmonella paratyphi) infection via fecal oral route survives in gastric acid and enters blood. Common in india + s/c america
- Symptoms: 7-14 days post, fever, anorexia, malaise, abdo pain, constip/diarr, dry cough
- Signs: fever, bradycardia, hepatosplenomegaly, rose spots (more common in paratyphoid)
- Investigations: stool culture, blood culture, fbc (dec wcc, anaemia), crp inc, lfts inc
- Management: iv ceft, then switch to cipro/azithromyocin once culture back. Need 3 neg stool cultures until can go back to work. Vaccine + water hygiene before going abroad
- Complications: intestinal haemorrhage, perforation, osteomyelitis, meningitis
Meningitis:
- Causes: neonates, child, elderly, immunosupp, viral
- Risk factors
- Symptoms
- Signs
- Complications
- Investigations
- Contraind LP
- Management
Meningitis:
- Causes:
neonates: ecoli, group strep b
child: haem influ, neisseria
elderly: strep peneum
immunosupp: listeria monocytogenes
viral: hsv, enterov (cocsackie), varicella
- Risk factors: ear implants, spinal procedure, endocarditis, splenectomy, crowded house
- Symptoms: nuchal rigidity, fever, altered mental status - photophobia, headache, seizures
- Signs: non blanching rash if meningococcal septicaemia, kernig (ext knee = resis), brudzinski (flexion neck = flex knees + hips)
- Complications: sepsis, cerebral oedema, siadh, hearing loss
- Investigations: fbc/crp/u+es/lfts, cultures, LP for bacterial culture/viral pcr/cell count/protein/glucose, lp not needed if rash just meningococcal pcr
No LP if: papiloedma, gcs<12, bleed risk, resp/cardio compromise, signs sepsis
bacterial: cloudy, inc wcc (neuts), dec glucose, inc protein, + gram stain
viral: inc wcc (lymph), normal or inc protein
TB: fibrin web, dec glucose, inc protein, inc wcc (lymph)
- Management: if in gp 1M benzylpenicillin. dexameth within 12 hours abx, analgesia, single dose cipro if contact within 7 days (or rifampicin), acyclovir
<3 months : cefotxime + amoxicillin
3 months - 50yrs: cefotaxime
>50: cefotaxime + amoxicillin
If meningococcal: iv benzylpenicllin + cefotaxime
Dengue fever:
- Definition
- Symptoms
- Signs
- Investigations
- Management
- Complications
Dengue fever:
- Definition: rna arbovirus (flavivirus) caused by black mosquito common in s/c america, thailand, africa, india
- Symptoms: post 1-5 days abrupt onset fever, severe myalgia, retroorbital headache, pleuritic chest pain, facal flushing
- Signs: fever, tachyc, widespread maculopapular rash 2-5 days post fever
- Investigations: stool culture, fbc (dec wcc, dec platelets)/lfts, blood cultures x2, dengue pcr, igm ns1 ag serology, cxr (normal)
- Management: supportive - fluid resus, blood
- Complications: can get dengue haemorrhagic fever (a form of DIC resulting in thrombocyt + spont bleeding) or dengue shock syndrome if reinfected with another serotype as there is ab developed enhancement
TB:
- Definition + pathophysiology
- Risk factors
- Latent tb test + management
- Active tb investigations
- Pericardial tb signs, complications, management
- Meningeal tb symptoms, investigations, management
- Miliary tb investigations
- Management
TB:
- Definition: mycobacterium tuberculosis infection. Primary infection can develop in lungs and a lesion called Ghon focus (tubercle laden mO) forms. This with hilar lymph nodes is called ghons complex where formation of caseous necrotic centre of granulomas (epitheloid histiocytes). This lesion can fibrose in normal people but can form miliary tb in immunocomp. If host becomes immunocomp then initial infection becomes reactivated in secondary tb (steroids/hiv/malnut). Can also affect cns, vertebral bodies (potts disease), renal, gi, pericardium
- Risk factors: country, exposure, immunocomp, hiv, apical fibrosis
- Symptoms: cough, hemoptysis, lethargic, fever, night sweats, weight loss, lymphadenopathy, erythema nodosum, spinal pain, clubbing
- Latent tb test + management: assymp + non infectious - + mantoux tuberculin skin test >5mm (not accurate if extreme age, fever, sarcoidosis, immunosupp) or + interferon gamma release assay (quantiferon), normal cxr. 3 months isoniazid + rifampicin if <35 + hepatotoxicity risk or 6 months isoniazid esp if hiv/transplant
- Active tb investigations: cxr (upper lobe cavitation, bilat hilar lymphad, pleural effusions), 3x sputum smears stained for acid fast bacilli (ziehl neelsen stain - bright red rods against blue), sputum culture x3 gold standard but takes 1-3 weeks, NAAT results within 24-48 hours
- Pericardial tb signs, complications, management: pericardial rub
- Meningeal tb symptoms, investigations, management: needs LP. Mx for 12 months
- Miliary tb investigations
- Management
rifampicin: orange urine, hepatotoxicity, flu - 6 months
isoniazid + pyridoxine: peripheral neuropathy, hepatotoxicity - 6
ethambutol: vision disturbances optic neuritis - 2
pyrazinamide: hyperuricaemia, hepatotoxicity - 2
Measure lfts + visual acuity before.
Also test for other infections, contacts, notify public health, isolate for at least 2 weeks of treatment
Can get paradoxical reaction where inc in inflamm as bacteria die so can give steroids
Pyrexia of unknown origin:
- Definition
- Causes
- Investigations
- Management
Pyrexia of unknown origin:
- Definition: >38c, ill >3 weeks, no diagnosis despite 1 week of inpatient ix
- Causes:
infection (tb, endocarditis, abscesses, hiv)
neoplastic (rcc, lymphomas, leukaemias)
autoimmune
other: hyperthy, vte, adrenal insuff
- Investigations: hx (travel, occupation, animal, meds), fbc/crp/esr/hiv/cultures, urine, cxr, ct
- Management: don’t start empirical abx
Human immunodeficiency virus:
- Definition
- Symptoms
- AIDs conditions
- Transmission
- Investigations for newly diagnosed patients
- Management
- Post exposure mx
Human immunodeficiency virus:
- Definition: rna virus infects cd4 t helper + mO cells
- Symptoms: flu symptoms within first few weeks (sore throat/lymphad, diarr, maculopap rash, ulcers), assymp until immunocomp/aids
- kaposis sarcoma (hhv8, brown spots + resp involvement), tb, cerebral lymphomas (single lesion on ct assoc with ebv - steroids, chemo), cytomegalovirus, pneumocytitis jirovecci pneumonia (fungus causing dry cough, desat on exercise, pneumothorax, hepatomeg - cxr shows bilat pul infiltrates - needs cotrim + steroids), toxoplasmosis (ring enhancing lesions on ct, needs sulfadiazine + pyrimethamine), cryptosporidium (diarrhoea), oesoph candidiasis, hairy leukoplakia
- Transmission: unp sex, needles, vertical
- Investigations for newly diagnosed patients: hiv ab test but takes 4-6 weeks to develop ab, hiv ab + p24 ag can be detected 2-3 weeks post so now first line, hiv viral load, cd4 count (500-1200, when <300 then aids). Test at 4 weeks if assymp, if neg repeat at 12
- Management:
2 nucleoside reverse transcriptase inhibitors (peripheral neuropathy) and either: non nucleos, integrase or protease inhibitor (diab, hyperlipid)
If cd4<200 cotrimoxazole
If <50 azithromycin for MAI + dilated fundoscopy
- Post exp: 1/300, nnrts + raltegravir 28 daysu
Hepatitis:
- Causes (5)
- Definition
- Symptoms
- Signs
- Investigations
- HepB
- HepC
Measuring antibiotic activity:
- Disc sensitivity testing
- Minimum inhibitory concentration
- MIC epsilometer test E-test
- measure diameter of zone of clearance via antibiotic discs
- a broth containing antibiotics in doubling concs - one with no colour is the min conc required for no growth
- again determines min inhibitory conc
Bites:
- animal bites organism
- animal bites mx
- human bites organism
- human bites mx
Bites:
- animal bites organism: pasteurella multocida
- animal bites mx: clean, don’t suture, coamox (deoxy + metron if allergy)
- human bites organism: strep, staph aures
- human bites mx: coamox 3 days (if signs infection 5 days)
abx if human bite where skin is broken/ dog bite where tissue damage/ cat bite drawn blood
Tetanus
- organism
- symptoms
- mx
Tetanus
- organism: tetanospasmin exotoxin from clostridium tetani
- symptoms: fever, headache, lethargic, trismus, facial spasms, opisthotonus (arched back, hyperext neck
- mx: muscle relaxants, venilation, IM human tetanus ig + vaccine if high risk injury if >10 years since tetanus vaccine, metronidazole
Notifiable disease
not hiv!!!
- encephalitis
- polio
- meningitis
- hepatitis
-enteric fever - hus
malaria - measles
etc
