Microbiology

Question 1

What are virulence factors?

Answer 1

Proteins contributing to variation in virulence between microorganism
organisms able to up or down regulate production depending on environment

Question 2

Adhesins

Answer 2

Enable binding of organism to host

These dictate where within the body the organism can take hold

Question 3

Invasin

Answer 3

Enables microorganism to invade host

Question 4

Impedin

Answer 4

Enables microorganism to avoid hosts immune system

Question 5

Aggresin

Answer 5

Cause direct damage to the host

Question 6

Modulin

Answer 6

cause indirect damage to the host

Question 7

Name two virulence factors associated with Staph.aureus

Answer 7

TSST-1 a superantigen binds directy to MHC II causing cytokine storm and inappropriate immune response
SSST Scalded skin syndrome a toxin which breaks down crossbridges between cells

Question 8

Clinical signs of toxic shock syndrome

Answer 8

Fever >39, diffuse macular rash, hypotension <90mmHg,

Question 9

Panton- Valentine Leukocidin- PVL toxin

Answer 9

Has a specific toxicity to leukocytes so removing immune response. Presence on skin isn’t an issue but very high mortality when present in the blood.

Question 10

What does PVL trigger?

Answer 10

Necrotising Pneumonia- rapid progression acute respiratory distress with refractory hpoxaemia

Question 11

Streptolysin S

Answer 11

a virulence factor which is a pore forming cytolising chemical toxic to organelles and platelets

Question 12

What does Streptolysin S result in?

Answer 12

Necrotising fasciitis- penetrates into dermis and mucous membrane and destroys connective tissue
Pain is out of proportion to the inflamed rash
Debridment is only cure

Question 13

Name three commensal bacteria found on the skin

Answer 13

Staph epidermidis
Diptheriods
Propionibacterium

Question 14

Name the types of bacteria likely to cause skin infections

Answer 14

Staph Aureus

B haemolytic group A

Question 15

Staph Aureus

Answer 15

Gram +ve Cocci in clumps, coagulase +ve,

Respire aerobically but can function anaerobically

Question 16

What is special about staph aureus?

Answer 16

Produces a protein which cause clothing off the blood plasma.

Question 17

Name three virulence factors linked to Staph Aureus?

Answer 17

SSST scalded skin syndrome toxin
PVL Panton Valentin Leukocidin toxin
Enterotoxin- food poisoning

Question 18

What antibacterial is used for Staph Aureus?

Answer 18

Flucloxacillin

Pen allergic use Vancomycin

Question 19

Staph Epidermidis

Answer 19

Skin commensal not commonly linked to infection

coagulase -Ve

Question 20

If upon swabbing Staph epidermidis keeps appearing what is likely route of infection?

Answer 20

Linked to artificial implant like heart valve catheter IV lines etc

Question 21

Staph Saphrophyticus

Answer 21

Linked to urinary tract infections in women of child bearing age

Question 22

Streptococcus

Answer 22

gram +ve chains

Question 23

B haemolytic Group A

Answer 23

Strep Pyogenes

Common in infected eczema and impetigo

Question 24

Treatment for Strep Pyogenes?

Answer 24

Penicillin if no Staph aureus is found, if Staph Aureus is present treat with flucloxacillin.

Question 25

What is the term for ringworm?

Answer 25

Tinea

Tinea pedis is when its located on the foot

Question 26

What is commonest organism affecting humans?

Answer 26

Trichophyton Rubrum

Question 27

What is the treatment for ringworm?

Answer 27

Small area- Co-trimazole

Terbinafine- taken orally