Past MCQs

Question 1

Is Salmonella Urease positive or negative?

Answer 1

Urease positive

Question 2

What media would be most suitable for isolation of Salmonella enterica serotype typhi? Why?

Answer 2

Bismuth Sulphite agar
Selective for Salmonella species

Question 3

How will S. typhi grow on Bismuth Sulphite agar

Answer 3

Black colonies surrounded by brownish-black zone

Question 4

What part of the Salmonella bacterium are the O (somatic) antigens found on?

Answer 4

Lipopolysaccharide

Question 5

What is the optimal enrichment medium for the isolation of Salmonella?

Answer 5

Selenite cystine broth

Question 6

What media is best for the selective isolation of Corynebacterium diptheria?

Answer 6

Hoyle’s Tellurite agar

Question 7

How does Corynebacterium diptheria grow on Hoyle’s Tellurite agar

Answer 7

Grows as black/grey colonies

Question 8

White kind of infection does H. influenzae commonly cause?

Answer 8

Acute bronchitis

Question 9

What would slender gram negative coccobacilli in a sputum gram stain indicate?

Answer 9

Haemophilus influenzae

Question 10

How does S. pyogenes grow on MacConkey agar?

Answer 10

S. pyogenes is usually unable to grow

Question 11

What biochemistry CSF results would you expect from a bacterial meningitis

Answer 11

Increased protein
Decreased glucose

Question 12

How does viral meningitis affect CSF glucose levels?

Answer 12

Shouldn’t really affect glucose levels

Question 13

For how long should blood cultures be incubated when querying sub-acute bacterial endocarditis

Answer 13

21 days

Question 14

What is meant by sterile pyuria and what would cause this

Answer 14

High white blood cells in urine
Without culturable bacteria

Antibiotic treatment
Non culturable organisms e.g. TB or Chlamydia
Cancer of bladder/urinary tract

Question 15

What would indicate a contaminated urine specimen

Answer 15

Squamous epithelial cells

Question 16

What is cystitis and what is a common cause in young women?

Answer 16

Inflammation of the bladder

95% of cases = E. Colil

Question 17

What media does EUCAST recommend for disc sensitivities for non fastidious organisms

Answer 17

Mueller-Hinton agar

Question 18

What does EUCAST stand for

Answer 18

European Committee on Antimicrobial Susceptibility Testing

Question 19

Give an example of an obligate anaerobe which is usually susceptible to metronidazole

Answer 19

Bacteroides fragilis

Question 20

Give an example of an organism where extended spectrum beta-lactamases may be detected

Answer 20

Escherichia coli

Question 21

What gene is responsible for MR in staph aureus

Answer 21

MecA

Question 22

Is E. Coli O157 able to ferment sorbitol?

Answer 22

No -> usually unable to ferment sorbitol

But normal E. Coli is able to

Question 23

What is the only non zoonotic Enteric organism (generally)

Answer 23

Shigella dysenteriae

Question 24

How is C.diff diagnosed

Answer 24

Demonstration of enterotoxin A and cytotoxin B in patient faeces

Question 25

Give an example of a hazard group 3 pathogen

Answer 25

Mycobacterium tuberculosis

Question 26

What is Hoyles tellurite used for?

Answer 26

Corynebacterium diphtheriae

Question 27

What does sodium poylanetholsulfonate (SPS) in blood culture media do?

Answer 27

Inhibits phagocytosis and bactericidal activity of serum Inactivates complement Neutralises lysozymes and aminoglycosides i.e. keeps organisms alive -> stops immune reaction in patient blood prevents the killing of bacteria by innate cellular and humoral factors

Question 28

What bio results would you expect in the CSF of someone with bacterial meningitis?

Answer 28

Increased protein Decreased gluocse

Question 29

What test is used to differentiate C. albicans from other Candida species

Answer 29

Germ tube test

Question 30

What would indicate renal damage in urine specimen

Answer 30

Protein casts

Question 31

Is Proteus mirabilis urease positive or negative?

Answer 31

Urease positive

Question 32

What is the germ test for Candida

Answer 32

We dont do this Fungal spores are suspended in animal serum and examined by microscopy

Question 33

What would coffin-shaped crystals in urine indicate

Answer 33

Triple phosphate crystals

Question 34

What organism cultured from a superficial wound swab is most associated with impetigo and scalded skin syndrome?

Answer 34

Staphylococcus aureus

Question 35

What are some tell tale symptoms of S. aureus wound infection

Answer 35

Impetigo Scalded skin syndrome

Question 36

What MacFarland standard is required for disc sensitivities by EUCAST

Answer 36

0.5 MacFarland

Question 37

What is the commonest reported cause of bacterial gastroenteritis in Ireland

Answer 37

Campylobacter jejuni

Question 38

What organism is associated with pseudomembraneous colitis

Answer 38

C. diff

Question 39

How would you make chocolate agar more selective for H. influenzae for use on a sputum sample

Answer 39

Add bacitracin

Question 40

What is the most common cause of pharyngitis

Answer 40

Viruses

Question 41

What is the most common cause of "swimmer's ear"/acute diffuse ottis externa

Answer 41

Psuedomonas aeruginosa

Question 42

What is the most important virulence factor of pathogenic S. pneumoniae

Answer 42

Polysaccharide capsule

Question 43

What is the most common cause of meningitis in neonates

Answer 43

Streptococcus agalactiae (BHS)

Question 44

What would be indicative of a sub-arachnoid haemorrhage in a CSF

Answer 44

Yellow coloured CSF Xanthochromia of CSF

Question 45

What is a bladder infection known as

Answer 45

Cystitis

Question 46

What infection does S. saprophyticus most commonly cause?

Answer 46

Urinary tract infection in the sexually active young women

Question 47

How should you report the resistance of MRSA?

Answer 47

Resistance to all beta-lactams

Question 48

Generally how are all wound swabs cultured?

Answer 48

Aerobically and anaerobically