Microbiology

Question 1

boil with pus on child’s forehead

purple cocci in clusters

Answer 1

S. aureus

Question 2

20yo student fever headache
CSF sample
pink diplococci

Answer 2

N. meningitidis

Question 3

Blood culture from febrile 62yo woman with pain and burning on passing urine
gram negative rods

Answer 3

E.coli

Question 4

CSF sample from neonate febrile and irritable

purple rods

Answer 4

Listeria

Question 5

57yo woman went to dentist 2 months ago
night sweats and malaise
chains of purple cocci
green halo on culture
grows around optochin

Answer 5

strep viridans

Question 6

What do the organisms usually cause depending on their Lancefield group?

Answer 6

A, C, G- tonsillitis, skin infections
B- neonatal sepsis and meningitis
D- UTIs

Question 7

what is the purpose of the optochin disc?

Answer 7

to differentiate between alpha haemolytic strep

Question 8

what is the purpose of the Lancefield test?

Answer 8

to differentiate between beta-haemolytic strep by detecting surface antigens

Question 9

What are the sterile sites in the body?

Answer 9

lungs- pleural fluid
blood
CSF
peritoneal cavity
Lower resp tract
urinary tract
joints

Question 10

Where are commensal bacteria found in the body?

Answer 10

skin
mouth
vagina
large intestine
urethra

Question 11

Which bacteria can cause bloody diarrhoea?

Answer 11

Shigella dysenteriae
E. coli
Campylobacter jejuni
Yersinia spp
Salmonella spp

Question 12

Which viruses can cause bloody diarrhoea?

Answer 12

rotavirus
norovirus
adenovirus

Question 13

Which protozoa can cause bloody diarrhoea?

Answer 13

Entamoeba histolytica

giardia lamblia

Question 14

Which agar can be used to isolate identify salmonella and shigella?

Answer 14

XLD and MacConkey (non-lactose fermenting)

Question 15

How do you distinguish between salmonella and shigella?

Answer 15

oxidase test
positive = salmonella
negative = shigella

Question 16

Which viruses would you test for when doing a respiratory PCR?

Answer 16

influenza A/B
parainfluenza 1-4
respiratory syncytial virus
rhinovirus
adenoavirus
coronavirus

Question 17

What 3 different markers are searched in an HIV blood test?

Answer 17

viral RNA
COBAS antigen
COBAS antibody

Question 18

Which viruses cause viral meningitis?

Answer 18

enterovirus
herpes simplex
varicella zoster
adenovirus

Question 19

When is retesting for HIV indicated?

Answer 19

clinical suspicion of seroconversion illness

high risk exposure in last 3 months

Question 20

22yo woman 24hr hx of severe pleuritic chest pain, breathlessness, productive rusty sputum, very unwell.
blood and sputum culture show Strep pneumoniae
what is the final diagnosis and which antibiotic is first line for this organism?

Answer 20

invasive pneumococcal pneumonia

amoxicillin

Question 21

List the atypical pathogens that can cause community acquired pneumonia.

Answer 21

chlamydophila psittaci
mycoplasma pneumoniae
coxiella burnetti
legionella pneumophila

Question 22

Which antibiotics would you use against atypical pathogens causing community acquired pneumonia?

Answer 22

macrolides (clarithromycin, erythromycin)
fluoroquinolones (ciprofloxacin, levofloxacin)
tetracycline (doxycycline)
amoxicillin does not work
clarithromycin is first line for legionella

Question 23

Which bacterium grows on chocolate agar but not blood?

Answer 23

H. influenzae

Question 24

What antibiotics should be used to treat a H. influenzae infection?

Answer 24

amoxicillin, doxycycline

Question 25

What is the first line antimicrobial used to treat a pneumocystis jirovecii infection?

Answer 25

co-trimoxazole | with prednisolone if significant type 1 failure

Question 26

Which antibiotics would you use to treat an exacerbation of bronchiectasis caused by P. aeruginosa?

Answer 26

antipseudomonal beta lactam like ceftazidime | fluoroquinolone like ciprofloxacin

Question 27

What marks would you expect to see on the nails of a patient with infective endocarditis?

Answer 27

splinter haemorrhages

Question 28

What is the standard antibiotic treatment for endocarditis caused by Strep viridans and for how long?

Answer 28

benzyl penicillin high dose for 6 weeks | synergistic gentamicin

Question 29

What is the standard antibiotic against staph aureus?

Answer 29

flucloxacillin (beta lactam penicillin)

Question 30

Which medium is specific to campylobacter?

Answer 30

charcoal cefazolin sodium decarboxylate agar

Question 31

List diarrhoea-causing pathogens that can be detected with stool microscopy.

Answer 31

cryptosporidium parvum entamoeba histolytica giardia lamblia schistosoma mansoni

Question 32

Which bacterium is responsible for antibiotic-associated diarrhoea?

Answer 32

Clostridium difficile

Question 33

Which antibiotics would you use to treat a clostridium infection?

Answer 33

metronidazole (because it is anaerobic) | oral vancomycin

Question 34

What empirical antibiotics would you start a patient on who is suspected to have an enteric bacterial infection?

Answer 34

cefuroxime/co-amoxiclav and metronidazole

Question 35

A 48yo woman unwell with fever, jaundice, severe RUQ pain and tenderness. Blood test reveals neutrophil leucocytosis with raised alkaline phosphatase and bilirubin. US of abdomen shows thick walled gall bladder with gall stones and dilated common bile duct. What is the probably surgical diagnosis and which empirical antibiotic would be appropriate?

Answer 35

acute cholecystitis co-amoxiclav

Question 36

What additional tests would you perform in someone with (MRSA) bacteraemia?

Answer 36

echocardiogram to check for IE | MRI spine to check for discitis

Question 37

Which antibiotics would you use to treat UTI caused by amoxicillin-resistant E.coli/klebsiella?

Answer 37

trimethoprim | nitrofurantoin or co-amoxiclav

Question 38

Which bacteria are likely to cause meningitis in neonates?

Answer 38

E.coli Group B strep listeria monocytogenes

Question 39

Which bacteria are likely to cause meningitis in infants?

Answer 39

N. meningitidis H. influenzae S. pneumoniae

Question 40

Which bacteria are likely to cause meningitis in young adults?

Answer 40

N. meningitidis | S. pneumoniae

Question 41

Which bacteria are likely to cause meningitis in the elderly?

Answer 41

S. pneumoniae N. meningitidis Listeria

Question 42

What are the viral causes of meningitis?

Answer 42

``` mumps virus echo virus coxsackie virus other enteroviruses herpes simplex virus lymphocytic chorio meningitis virus poliovirus ```

Question 43

How would you manage a patient with meningitis caused by strep pneumoniae?

Answer 43

``` IV cefotaxime IV dexamethasone (pneumococcal infections cause a lot of inflammation which can increase the risk of long term sequelae like deafness) ```

Question 44

What groups are at risk of meningitis due to Listeria monocytogenes?

Answer 44

``` immunocompromised alcohol dependency diabetes pregnancy HIV long-term steroids children elderly ```

Question 45

Why should a lumbar puncture not be performed in someone with suspected meningitis back rash?

Answer 45

No. The presence of a characteristic rash and the presentation raises a strong clinical suspicion of meningococcal septicaemia and meningitis. There is no need to do a lumbar puncture and may be harmful in the event of coagulation abnormalities secondary to the meningococcal sepsis. The diagnosis can often be confirmed by either peripheral blood culture or peripheral blood molecular testing for N.meningitis (ie. PCR). bacteria can get into sterile CSF

Question 46

What actions (other than treating the pt) need to be taken when someone has confirmed meningitis?

Answer 46

notify public health England prophylaxis in close contacts- single dose ciprofloxacin/rifampicin vaccinate others

Question 47

In a drowsy and confused elderly patient with suspected meningitis, what therapy should be started whilst awaiting lab results?

Answer 47

IV antibiotics for possible bacterial meningitis | IV acyclovir to treat possible herpes simplex virus