Microbiology Flashcards
(129 cards)
1
Q
describe the appearance of listeria monocytogens
A
β-haemolytic anaerobic Gram-positive rod/ bacillus
2
Q
common cause of travellers diarrhoea
A
e. coli
3
Q
casues of non-bloody diarrhoea
A
giardia
vibrio cholera
bacillus cereus
4
Q
pt develops sudden diarrhoea and non bloody diarrhoea after eating re-heated rice
A
Bacillus cereus
5
Q
pear-shaped trophozite containing two nuclei, four flagellae and a suction disc is…
A
Giardia lamblia
6
Q
anaemia, thrombocytopenia and renal failure
A
haemolytic uraemic syndrome casued by 0157:H7 toxin from E. coli
7
Q
Examples of live attenuated vaccination
A
live pathogen but made less pathogenic (is grown in non human tissue)
(MMR-VBOY)
MMR
VZV
BCG
oral- polio, typhoid
yellow fever
8
Q
examples of inactivated vaccines
A
quadravalent influenze
polio
cholera
bubonic plague
hepA
Rabies
Pertussis
9
Q
examples of conjugate vaccines
A
(NHS-T)
N meningitidis
H influenzae
Strep pneumonia
Tetanus
10
Q
examples of DNA/RNA vaccines
A
Sars-CoV-2 (mRNA)
adenovirus
11
Q
examples of adjuvents
A
alum (most common)
CpG
complete freunds adjuvent
12
Q
mechanism of alum as an adjuvent
A
antigens absorbed into alum as a means of slowly releasing the antigen
activates Gr1+ cells produce IL4 –> primes naiive B cells
13
Q
mechanism of CpG as an adjuvent
A
activates TLR on APCs
14
Q
causes of bloody diarrhoea
A
shigella
campylobacter jejuni
E.coli
entamoeba hystolytica
salmonella
yersinia
15
Q
comma shaped bacteria
A
vibrio cholera
16
Q
what is the difference in pattern of paralysis between GBS and clostridium botulinum
A
GBS- ascending paralysis
C. botulinum- descenting paralysis
17
Q
Rose spots are pathopneumonic for what infection
A
Salmonella typhi
18
Q
flask shaped ulcer is caused by what infection?
A
Entamoeba hystolytica
19
Q
CSF analysis shows very high protein, low glucose and high lymphocytes is likely to be…
A
mycobacterium tuberculosis meningitis
20
Q
what kind of media is best for culturing neisseria meningitidis
A
grown best on Thayer–Martin VCN media as only allows n. meningitidis to grow
21
Q
what is the causative organism of lyme disease
A
borrelia burgdorferi
22
Q
Gram-negative coccobacillus that causes a painful ulcer
A
Haemophilus ducreyi
23
Q
differential diagnosis for genital ulcer
A
PAINFUL:
Herpes simplex
haemophilis ducreyi
PAINLESS:
primary syphilis
lymphogranuloma venerum
24
Q
what STI can be cultured on chocolate agar?
A
haemophilus ducreyi
25
drug of choice in cases of methicillin-resistant Staphylococcus aureus infections (MRSA)
vancomycin
26
side effects of chloramphenicol
aplastic anaaemia
27
complications of human herpes virus 8
Kaposi's sarcoma
multicentric castleman disease
primary effusion lymphoma
28
antiviral used in the treatment of influenza
oseltamivir
29
causative organisms of encephalitis
HSV1, west nile virus, flavivirus
listeria monocytogens encephalitis (worse than listeria meningitis)
Amoebic: naegleria fowleri, habitat, acanthoemeba
toxoplasma gondii (cats)
30
bacterial causative organisms of meningitis
direct bacterial toxicity or indirect inflammatory reponse
N. meningitidis , strep pneumoniae, H influenzae
neonate and elderly: GBS, listeria, E.coli
Chronic: TB
31
causative organisms of
32
causative organisms of
33
common viral casues of meningitis
enteroviruses (coxsackie, echovirus), mumps, HSV2, measles, VZV
(usually asceptic meningitis)
34
brain abscess pathology
otitis media/mastoiditis/paranasal sinuses
endocarditis/haematogenously
Microbiology:
Streptococci (both aerobic and anaerobic)
Staphylococci,
Gram-negative organisms. (particularly in neonates)
Mycobacterium tuberculosis
fungi
parasites
Actinomyces and Nocardia species
35
causes of viral hepatitis
hepatitis A-E
EBV
CMV
36
describe Hepatitis A
faecal-oral transmission
only ever acute
2-6wks incubation period
37
symptoms of acute hepatitis
Non-specific systemic Sx:
fever, malaise, fatigue, loss appetitte
Abdo pain
Acute raised bilirubin:
Jaundice
dark urine
(pale grey or white stool)
puritis
38
Investigations for HAV
anti-HAV IgM- acute infection
may be neg first week
anti-HAV IgG- immunity
If ALT>500- order IgM as IgG will not be high yet so will give a false negative
39
Managament of hep A
mainly supportive
vaccination is available but not in UK
40
describe Hepatitis B
parental, vertical, sexual
2-6 months incubation
41
what defines chronic HBV and what are the complications
HBsAg reactivity persisting >6months
comp:
Cirrhosis
hepatocellular carcinoma
extra hepatic manifestations
42
describe HBV serology
HBsAg- if positive= active infeciton
E antigen- denotes viral replication and will be high with a high viral load
HBcAg- acute infection
AntiHBc Ab- past or present exposure
antiHBs- immune either from infection or immunisation
43
radiological findings of cirrhosis
coarse echotexture, nodularity, portal HPTN- splenomegaly
44
tumour marker for hepatocellular carcinoma
alfa fetoprotein
45
when is HBV vaccine given
2,3,4 months
46
screening in pregnancy
HBsAg positive, eAg negative: vaccine at birth + routine
schedule
HBsAg positive, eAg positive: vaccine at birth PLUS
HBIG within 48 hours
47
Describe Hep C
ssRNA, flavivirdae
transmission through blood products, sharing needles, sharing snorting
2wk-6month incubation
40-60%
progress to
chronicity
48
Investigations for HCV
Hep C RNA PCR should be requested if acute infection suspected
If RNA is negative then it means pt does not have infection
if anti-HCV Ab positive- exposure
49
managament of HCV
Acute infection:
treated with direct acting antivirals
12wk Tx course OD
50
describe hepatitis D
Only co-infects with hepatitis B leading to severe acute disease
vaccination agains hep B will protect against hep D
51
describe hepatitis E
hepeviridae ssRNA virus
2-8wks incubation
never chronic infection except in immunocompromised
30% mortality in pregnant women
52
extrahepatic manifestations of hepatitis E
thrombocytopenia, red cell aplasia
proximal myopathy, necrotising myositis
encephalitis, ataxia, brachial neuritis
membranoproliferative glomerulonephritis, IgA nephropathy
53
extrahepatic manifestations of hepatitis B
polyarteritis nodosa
sick serum syndrome
arthritis
cryoglobulinaemia
54
extrahepatic manifestations of hepatitis C
cryoglobulinaemia
glomerulonephritis
55
in what situations would a viral infection required treatment with antivirals
COVID- resp failure
chicken pox- varicella pneumonitis
herpes- encephalitis
viral hep- chronic hep C
monkey pox - eye lacerations
56
general rule of Acute vs chronic infection in terms of DNA and RNA viruses
RNA viruses- acute and generally cleared by immune system (exception to retroviruses)
DNA viruses - chronic infections as they find ways to hide within human body
57
treatment for HSV encephalitis
Start empiric treatment immediately with iv Acyclovir 10mg/kg tds without waiting for test results
If confirmed, treat for 14 - 21 days *
58
MOA of acyclovir
guanasine analogue
inhibits DNA synthesis
59
what metabolises acyclovir to make it active
viral thimadine kinase
60
complications of CMV in immunocompromised
Colitis
Pneumonitis
Hepatitis
Retinitis
Bone marrow suppression
only treat CMV with signs of complications not just infection
61
what are owls eyes inclusions a sign of
CMV colitis
62
complications of congenital CMV infection
ears: sensorineural deafness
eyes: chorioretinitis
heart: myocarditis
neurology: microcephaly, encephalitis
lung: pneumonitis
63
complication of chronic EBV infection
Chronic infection in immunocompromised-> Post-Transplant Lymphoproliferative
Disease Latently infected B cells – polyclonal expansion
Predisposes to lymphoma
64
most common cause of bronchiolitis
Respiratory syncytial virus
65
Treatment of bronchiolitis in severe cases
- mostly untreatable
- ribavirin
- IgG
66
What is used as propylaxis for RSV infection
prevention- palivizumab
67
antiviral drugs in COVID
early infection- antivirals:
-Nirmatrelvir, remdisivir
Late
- steroids
Baricitinib (requiring O2) – JAK inhibitor
IL-6 inhibitors (Tocilizumab / Sarilumab) – advanced respiratory support
68
complications of BK virus
haemorrhagic cystitis
BK Nephritis & ureteric stenosis
69
what is the main mechanism of resistance for acyclovir
thymidine kinase mutation
- enzyme involved in metabolising acyclovir to an active form to stop viral DNA synthesis
70
3 taxonomic families of parasites
Cestodes (hydatid, tapeworm)
Trematodes (lung, liver and intestinal fluke, schisto
Nematodes (roundworms- hookworm, ascarids, strongyloids)
71
treatment of worms
praziquantel
72
example of a hydatid disease and what is the definitive host?
echinococcus
dogs
73
what is the life cycle of schistosomiasis
Cercariae invade human skin when in contact with contaminated water.
Worms develop in venous plexus
Eggs excreted in faeces or urine
Hatch into miracidia, which parasitise snails
Snails release cercariae
Adult schistosomes lay eggs:
Migration of eggs through bladder or bowel causes damage
Retrograde passage of eggs into the liver causes “cirrhosis”
74
diagnosis of schisto
microscopy:
Urine: S. haematobium
Stool: S. mansoni, S. japonicum
serology
biopsy
75
signs and symptoms of schisto
fevers, chills
chronic: cirrhosis
76
examples of soil transmitted helminths
ascaris lumbricoides
trichuris trichiura
hookworm
strongyloids stercoralis
77
incubation period of p falciparum malaria
1wk-3months
78
incubation period of viral haemorrhagic fever
3-21 days
79
treatment for p falciparum
SEVERE: IV artesunate
MILD: oral artemisinin combination therapy eg. riamet,
malerone
80
what investigation do you need to determine severe from non severe maleria
parasitaemia
81
examples of malarial prophylaxis
malarone
mefloquine
doxycycline
82
presentation of malaria
~15 days after bite (vivax several months, falciparum ~10-30days)
fevers- cyclical or ontinuous with spikes
chills, sweats
altered GCS
resp distress
AKI
hepatic failure
coagulopathy
haemolytic anaemia
hypoglycaemia
83
schiznot : spot diagnosis
maleria
84
treatment of non-falciparum
3 days oral chloroquine + primaquine 14 days after
CHECK G6PD deficiency
85
spot diagnosis:
can leave palm print on rash, thrombocytopenia
dengue
86
what is dengue spread by
ades aegypti mosquito
(bites during the day)
87
symptoms of dengue
can be asymptomatic
retro-orbital headache
myalgia
nausea, vomiting
sunburn rash- palm print
severe abdo pain
ecchymoses
organ impairment
shock
88
anorexia, constipation, abdo pain
vacant expression
T39 (himalaya peak temps), HR90
normal Plts
returned from india
gram negative rod on culture
salmonella typhi
89
management of salmonella thyphi
fluids
IV ceftriaxone with oral azithromycin follow on
90
Abx of choice for MRSA
vancomycin
91
what is the cell targeted by EBV and what does it bind to
B cells
binds to complement receptor
92
opportunistic infections / AIDS defining
pneumocystis jerovecii
TB
JC virus- progressive multifocal leukoencephalopathy
cryptococcus neoformans
Candida
toxoplasmosis
oral hairy leukoplakia
shingles
93
causes of a ring enhancing lesion with oedema on brain MRI
toxoplasmosis
TB
Bacterial brain abscess
primary CNS lymphoma
94
uveitis, genital ulcer, oral ulcer
japanese
Bechets
95
Cancer of what organ is commonly associated with schistosomiasis infection?
bladder
96
lancfield grouping used to classify which type of pathogenic organism
streptococci
97
what is the treatment for visceral leishmaniasis
Liposomal amphotericin B
98
treatment of tapeworms
praziquantel
99
What is the primary infective lesion produced by Mycobacterium tuberculosis called in the lungs?
ghon focus
caseating granuloma
100
Give an example of a scoring system which can be used in primary care to guide if antibiotics may be beneficial for a sore throat?
CENTOR
fever, tonsillar exudate, anterior cervical lymphadenopathy, and absence of cough
101
A Löwenstein-Jensen medium is used to facilitate growth of what respiratory pathogen?
TB
102
Most common cause of aseptic meningitis
Enteroviruses eg. Coxackie or echovirus
103
how is cellulitis classified for treatment
Eron classification
I- systemically well and no comorbitities
II- comorbidities either systemically well or unwell
III- significant systemic upset including confusion, hypotension, tachycardia and comorbidities
IV- sepsis or nec fasciitis
admission for IV antibiotics
- class III or IV
- rapidly progressing
- <1year
- periorbital/ orbital cellulitis
104
most common organism found on central line infections
staph epidermidis
105
features of legionairres pneumonia and how is it diagnosed and treated ?
flu-like symptoms including fever (present in > 95% of patients)
dry cough
relative bradycardia
confusion
lymphopaenia
hyponatraemia
deranged liver function tests
pleural effusion: seen in around 30% of patients
diagnosis:
urinary antigen test
Rx:
erythromycin/ clarythromycin
106
features of leptospirosis, RFs and Rx
RFs:
sewage workers, farmers, returning travellers
features:
the early phase is due to bacteraemia and lasts around a week
may be mild or subclinical
fever
flu-like symptoms
subconjunctival suffusion (redness)/haemorrhage
second immune phase may lead to more severe disease (Weil's disease)
acute kidney injury (seen in 50% of patients)
hepatitis: jaundice, hepatomegaly
aseptic meningitis
Rx:
benzylpenicillin or doxycycline
107
describe the CURB 65 score
Confusion- 1
Urea >7mmol/L -1
RR >30 - 1
BP <90/60 -1
score 0-1: can be managed in community with amoxicillin PO for 5 days
score 2- amoxicillin PO 5-7 days + clarythromycin
consider admission
score 3-5 - admission, consider ITU, IV co-amoxiclav + clarythromycin 7d
108
mechanisms of antimicrobrial resistance and examples of each
BEAT
Bypass antibiotic sensitive step- eg. MRSA
Enzyme- mediated drug inactivation eg. beta-lactamases
Accumulation of drug impairment eg. tetracycline resistance
Target modification - eg. quinolone resistance
109
HIV positive, multiple ring-enhancing lesions on CT scan and a negative thallium SPECT scan.
toxoplasmosis
110
single, homogenous-enhancing lesion and a positive (rather than negative) thallium SPECT scan
CNS lymphoma
111
treatment for CNS toxoplasmosis infection in immunocompromised
sulfadiazine and pyrimethamine
112
antibiotics used for MRSA
1. vancomycin
2. teicoplanin
3. linezolid
113
what infection is commonly associated with post gastroenteritis lactose intolerance?
giardia lamblia
114
dry cough, arthralgia, cold agglutanin test/ AIHA, erythema multiforme
mycoplasma pneumoniae
115
treatment for genital warts
multiple, non-keratinised warts: topical podophyllum
solitary, keratinised warts: cryotherapy
116
post exposure prophylaxis for HBV
positive HBV-Ag
known responder to vaccine - give vaccine booster
known non responder or no vaccine- give IVIg and vaccine booster
117
features of HIV seroconversion
3-12 weeks post infection
lymphadenopathy
malaise, myalgia, arthralgia
diarrhoea
maculopapular rash
mouth ulcers
rarely meningoencephalitis
118
what should be done if an HIV+ person has a CD4+ count of <200/mm3
prescribe co-trimoxazole prophylaxis for PCP
119
which antibiotic is commonly associated with a disulfiram- like reaction when consumed with alcohol
metronidazole
Sx: nausea, vomiting and flushing
120
what is cushings triad
Sign of raised ICP
hypertension with a widened pulse pressure
bardycardia
irregular breathing
as a result of cerebrum compression
therefore LP contraindicated
121
what are some causes of a false positive non-treponemal test for syphilis (eg. VDRL, rapid plasma reagin test)
Some Times Problematic Mistakes Happen
SLE
TB
Pregnancy
maleria
HIV
122
Negative non-treponemal test + positive treponemal test :
consistent with sucessful treatment of syphilis
123
Positive non-treponemal test + negative treponemal test
consistent with a false-positive syphilis result e.g. due to pregnancy or SLE
124
Positive non-treponemal test + positive treponemal test
consistent with active syphilis infection
125
prophylaxis for animal bites
co-amoxiclav
or
doxy + metronidazole if penicillin allergic
126
antibiotics used for cellulitis
Eron I
flucloxacillin
erythromycin if penicillin allergic
Eron class II-IV
IV co-amoxiclav, clindamycin, erythromycin, ceftriaxone
127
lab features of pseudomonas aeruginosa
Gram-negative rod
non-lactose fermenting
oxidase positive
128
toxins produced by pseudomonas
produces both an endotoxin (causes fever and shock) and exotoxin A (inhibits protein synthesis by catalyzing ADP-ribosylation of elongation factor EF-2)
129
what antibiotic can cause a black hairy tongue after discontinuation
tetracyclines
