Staphlococcus

Question 1

Family

Answer 1

Micrococcaceae

Question 2

Important species

Answer 2

S.aureus,
S. epidermidis, and
S. saprophyticus

Question 3

Epidemiology

Answer 3

Normal flora of skin and na so pharynx

Question 4

Microbiology

Answer 4

Gram positive cocci in clusters, (Staphyle=bunch/grape-like); S. aureus (aureus=gold), on sheep blood. They are catalase positive.

G+ve cocci
-Catalase test+
Streptococcus Staph/Micrococcus
-VP test.+
Micrococcus Staphylococcus
-Coagulase test+
CNS Staph aureus

S 5ug Novobiocin R
•Staph. Epidermidis. Staph.saprophyticus.

Question 5

Protein A

Answer 5

-It binds the Fc portion of IgG and thus protects the organism against opsonisation & phagocytosis

Question 6

Coagulase

Answer 6

-It leads to fibrin formation around the bacterium and protects it as in No1 above.

Question 7

Haemolysins (4 types).

Answer 7

They are Toxins that destroy RBCs, Neutrophils, Macrophages & Platelets.

Alpha
Beta
Gamma
Delta

Question 8

Alpha Toxin (or haemolysin)-

Answer 8

causes critical necrosis. Lysis rabbit sheep,& cat RBCs and rabbit & human WBCs.

Question 9

Beta Toxin (or haemolysin)

Answer 9

Lysis sheep,human and Ox RBCs.

Question 10

Delta Toxin (or haemolysin)

Answer 10

Lysis RBCs and WBCs of all animals.

Question 11

Gamma Toxin (or haemolysin

Answer 11

acts like delta haemolysin.

Question 12

Enzymes produced by Staphylococci.

Answer 12

1. Coagulase.
   •2. Phosphatase.
   •3.Dnase
   •4. Hyaluronidase.
   •5. Staphylokinase.
   •6. Lipase.
   •7. Gelatinase

Question 13

Nb

Answer 13

Only Coagulase is unique to S.aureus; all other enzymes are produced by other species of Staphylococci.

Question 14

Enterotoxins.

Answer 14

1. Five types exist: A-E.
   •Types A & D-are associated with food poisoning.
   •Types C & E are associated with TSS.

Question 15

Exfoliatin

Answer 15

also called epidemolytic or exfoliative toxin, is reponsible for SSS (Scalded skin syndrome).

Question 16

Coagulase test:

Answer 16

a) Slide test: For bound coagulase.
•b) Tube test: For free& bound coagulase.

Question 17

Diseases caused by direct organ invasion by S.aureus.

Answer 17

1. Pneumonia.
   •2.Meningitis.
   •3. Osteomyelitis.
   •4. Acute bacterial endocarditis.
   •5. Septic arthritis.
   •6. Skin infections: (Abscesses,boils, carbuncles,furuncles, impetigo etc).
   •7. Bacteraemia/sepsis.
   •8. UTI by both S.aureus & S. saprophyticus.

Question 18

Diseases caused by exotoxins.

Answer 18

1. Gastroenteritis.
   •2. TSS-Toxic shock syndrome due to TSST-1 (Tampon associated).
   •3. Scalded skin syndrome-SSS-by exfoliative toxin A & B.

Question 19

Miscellaneous issues about Staphylococci.

Answer 19

•1. MRSA & VRSA.
•2. All Staphylococci are notorious for HAIs.
•3. Beta-haemolysis.
•4. Golden yellow colonies.
•5. Mannitol salt agar.
•6. SE-associated with prostheses infections.
•7. SS-associated wit UTI in sexually active women.

Question 20

Treatment

Answer 20

1. Penicillinase-resistant penicillins like Nafcillin,dicloxacillin.
   •2. Clindamycin.
   •3. Vancomycin.
   •4. Linezolid.

Question 21

•CONTROL:

Answer 21

Strict personal & community hygiene.