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Flashcards in Staphylococci Deck (20):
1

Is staphylococci Gram positive or Gram negative?
Does it stain purple or pink?

Gram-positive; stains purple

2

Describe the shape & structure of staphylococci colonies under the microscope

Round; irregular grape-like clusters of cocci

3

Is staphylococci catalase-positive or negative?

Catalase-positive

4

Name a coagulase +ve species of staphylococci

Staph. Aureus

5

Name a coagulase -ve species of staphylocci

Staph. Epidermidis

6

Habitat of Staph. Aureus

Anterior nares, skin, perineum

7

Haemolytic activity of Staph. Aureus

B-haemolysis

8

Colour of Staph. Aureus colonies on CBA

Golden-yellow; mostly white

9

Transmission of Staph. Aureus

1. Contact
- direct - hands, skin, mucous
- indirect - instruments, door handles, bedding
2. Airborne
- shedding of cocci from infected site into atmosphere
- Dust/squames

10

Superficial infections caused by Staph. aureus? (x4)

Abscesses, conjunctivitis, wound infections, boils

11

Symptoms/Diagnosis of Toxic Shock Syndrome (x4)

- fever (39deg)
- hypotension (b/p less than 90mmHg)
- Diffuse macular rash and desquamation
- More than 3 organ systems involved (liver/blood/renal/mucous membranes/GI/CNS)

12

Cause of toxic shock syndrome

exotoxin - toxic shock syndrome toxin 1 (TSST-1) - e.g. of superantigen

13

Deep infections caused by Staph. aureus? (x3)

1. Acute endocarditis - bacteria enters soft tissues and bloodstream during injections
2. Pneumonia
3. Septicaemia

14

What type of pathogen is Staph. Epidermidis?

Opportunistic pathogen

15

Infections caused by Staph. Epidermidis (x3)

Catheter-related sepsis
Infection of artificial joints
Urinary tract infections

16

Name 2 virulence factors associated with attachment (adhesins)

1. Fibrinogen-binding (ClfA ClfB)
2. Collagen binding (CNA)
- Extra-cellular matrix molecules are present on epithelial, endothelial surfaces as well as a component of blood clots
- Elastin binding proteins (Ebps)

17

Name some virulence factors associated with the evasion of host defences (x7)

1. Protein A (only for Staph. Aureus)
2. Proteases (V8)
3. Superantigens
4. Lipases, Phospholipases, Esterase
5. Gamma haemolysin (toxin) hlg & Leukocidin (PVL - Panton-Valentine Leukocidin)
6. Coagulase
7. Capsule

18

Name 3 virulence factors associated with invasion/tissue penetration

1. Hemolysins (alpha-toxins)
2. Hyaluronidase
3. Staphylokinase (Fibrinolysin) - digests fibrin

19

Treatment of Staphylococci (x6)

1. Flucloxacillin (Methicillin) - class of penicillin stable against B-lactamase
2. Erythromycin - for patients allergic to the penicillin class
3. Vancomycin - treatments for MRSA
4. Linezolid - treatments for VRSA
5. Fusidic acid - Useful for skin infections
6. Mupirocin - topical decontamination

20

Is penicillin useful in treating staphylococci infections?

no, 50-80% of staphylococci are resistant to penicillin