Bacteriology

Question 1

What important bone infection is caused by s aureus?

Answer 1

Osteomyelitis

Question 2

3 structural pathogenicity factors of s aureus?

Answer 2

Peptidoglycan
Protein A
Clumping factor

Question 3

3 types of exotoxins produced by s aureus?

Answer 3

Alpha to gamma lysins
TSST
Enterotoxins

Question 4

What is Panton-Valentine leukocidin and what does it do?

Answer 4

An exotoxin associated with highly virulent s aureus strains incl MRSA
Lyses polymorphonuclear leukocytes

Question 5

What disease is PVL associated with in kids?

Answer 5

Severe necrotising pneumonia

Question 6

Suitable antibiotics for MSSA?

Answer 6

Flucloxacillin

Macrolides, aminoglycosides

Question 7

Suitable antibiotics for MRSA?

Answer 7

Glycopeptides incl vancomycin, daptomycin

Linezolide

Question 8

What criteria defines B haemolytic streptococci as group A, B, C, D etc.? What does it describe?

Answer 8

Lancefield criteria

The antigens carried on the cell surface

Question 9

What is the extra cellular enzyme which distinguishes s aureus from other staphylococcus species?

Answer 9

Coagulate

Question 10

What are 2 examples of common alpha haemolytic strep?

Answer 10

Strep pneumoniae

Viridans group

Question 11

What do alpha haemolytic strep do to blood on blood agar?

Answer 11

Oxidise the intracellular iron, turning rbcs green

Question 12

What do beta haemolytic streptococci do to blood?

Answer 12

Completely haemolyse rbcs, leaving clear area on blood agar

Question 13

What do gamma haemolytic streptococci do to blood?

Answer 13

No haemolysing activity

Question 14

What are the 3 major groups of beta haemolytic streptococci?

Answer 14

A B D

Question 15

What is the archetypal group A strep?

Answer 15

Strep pyogenes

Question 16

What are the 2 major types of virulence factors on strep pyogenes (GAS)?

Answer 16

Streptolysins (O and S)

Streptococcal pyogenes exotoxins (Spe) A and C

Question 17

What are SpeA and SpeC responsible for?

Answer 17

Rash in Scarlett fever, streptococcal toxic shock syndrome

Question 18

What is acute rheumatic fever a complication of? Why does it occur?

Answer 18

Strep pyogenes (GAS) infection, usually respiratory
M protein generates cross reactive autoAbs to endocardial and synovial tissue

Question 19

How does acute rheumatic fever most commonly present? How else can it manifest?

Answer 19

As a migratory polyarthritis

Can also manifest as a pancarditis +/- pericarditis

Question 20

What is rheumatic disease of the heart?

Answer 20

A chronic inflammation of the endocardium (particularly mitral valve) due to previous acute rheumatic fever infection

Question 21

What is a renal complication of GAS infection?

Answer 21

Post-strep glomerulonephritis

Question 22

What is an important cause of puerperal fever/sepsis?

Answer 22

Strep pyogenes (GAS)

Question 23

What complication can GAS cause in new mothers?

Answer 23

Puerperal fever and sepsis

Question 24

What is the archetypal group B strep (B haemolytic)?

Answer 24

Streptococcus agalactiae

Question 25

What are the most important manifestation of GBS (strep agalactiae) infection?

Answer 25

Neonatal meningitis, sepsis, pneumonia (and old people) | Miscarriage, stillbirth, PPROM due to colonisation in maternal intestines and female reproductive tract

Question 26

What have many group D strep been recategorised as?

Answer 26

Enterococci

Question 27

What are 2 clinically relevant bacteria still classed as GDS?

Answer 27

Strep bovis and strep equinus

Question 28

2 common species of enterococci commensal in intestines?

Answer 28

``` Enterococcus faecalis (90%) Enterococcus faecium (10%) ```

Question 29

What haemolytic activity do most enterococci have? 2 exceptions?

Answer 29

Mostly gamma haemolytic E faecalis = sometimes alpha E faecium = sometimes beta

Question 30

What are enterococci examples of? How do they respire?

Answer 30

Lactobacilli - facultative anaerobes

Question 31

4 important clinical manifestations of enterococcus infection?

Answer 31

Diverticulitis UTI Endocarditis Meningitis

Question 32

What can an enterococci-induced UTI be treated with?

Answer 32

Nitrofurantoin

Question 33

What are all enterococci intrinsically resistant to?

Answer 33

Cephalosporins and many B lactams + aminoglycosides

Question 34

What other chronic condition are enterococci thought to be responsible for, due to biofilm formation?

Answer 34

Chronic bacterial prostatitis

Question 35

3 types of coliforms?

Answer 35

Klebsiella Enterobacter Fecal coliforms incl escherichia