microbiology

Question 1

what is an adhesin

Answer 1

enables binding of the organism to host tissue

Question 2

what is invasion

Answer 2

enables the organism to invade a host cell/tissue

Question 3

what is impedin

Answer 3

enables the organism to avoid host defence mechanisms

Question 4

what is aggressin

Answer 4

causes damage to the host directly

Question 5

what is modulin

Answer 5

induces damage to the host indirectly

Question 6

what are toxinoses

Answer 6

single component, can be made of multiple proteins, acting on distinct targets exported from infectious agent

TSST-1, staphylococcal food poisoning, SSS

Question 7

what are superantigens

Answer 7

common theme disrupting immune system and co-ordination by over stimulation

Question 8

what is the diagnostic criteria for toxic shock syndrome

Answer 8

fever
diffuse macular rash and desquamation
hypotension
>= organ systems involved

Question 9

examples of adhesins

Answer 9

• extra cellular matrix molecules
• fibrinogen binding
• fibronectin binding
• collagen binding
• elastin binding protein

Question 10

what is lancefield system

Answer 10

Lancefield grouping is a system of classification that classifies catalase-negative Gram-positive cocci based on the carbohydrate composition of bacterial antigens found on their cell walls

Question 11

examples of GAS skin diseases

Answer 11

impetigo
cellulitis
erysipelas

Question 12

where does staphylococcus colonise?

Answer 12

sebaceous gland

Question 13

what are some staph aureus skin presentations

Answer 13

rash
folliculitis
abscess
carbuncle
impetigo
scalded skin syndrome

Question 14

is S.aureus coagulase positive or negative

Answer 14

positive

Question 15

is s.epidermis coagulase positive or negative

Answer 15

negative

Question 16

what % colonisation is S. aureus

Answer 16

20

Question 17

what % colonisation is S. epidermis

Answer 17

100

Question 18

symptoms of TSST-1

Answer 18

rapid progression, high fever, vomiting, diarrhoea, sore throat, muscle pain
diffuse macular rash and desquamation, hypotension

Question 19

superantigen

Answer 19

toxic shock
activate 1 in 5 T cells
massive release of cytokines and inappropriate immune response

Question 20

what is panton-valentine leukocidin

Answer 20

specific secreted proteins that form one functional complex that attacks white blood cells

very damaging and can mean death

Question 21

what is necrotizing pneumonia

Answer 21

severe complication of quite mild infections due to destruction of immune cells

Question 22

what type of haemolysis is alpha haemolysis and what colour is it

Answer 22

partial on blood agar and green

Question 23

what type of haemolysis is beta and what colour

Answer 23

complete on blood agar and clear

Question 24

what type of haemolysis is gamma and what colour

Answer 24

no haemolysis on blood agar

Question 25

example of an iGAS disease

Answer 25

necrotizing fasciitis

• invasive strep A strains penetrate mucous membrane and develop in lesion
• severe infection

Question 26

what is streptolysin S (SLS)

Answer 26

• pore forming cytolysin
• toxic to PMN, organelles, platelets
• important in animal models
• responsible for beta haemolysis