Staphylococcus bacteria in microbiology

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Gram positive cocci

• Arrangement- In bunch / clusters (Grapes / Barry)

Coagulase positive for pathogenic


Cultural Character

• Salt tolerant organism

 (They required 7.8% salt in growth medium)

• NA- Convex, Circular, Shining, Opaque

 (Drop of Oil paint colony on slant)

❖ Golden yellow colony- S.aureus

❖ Lemon yellow colony- S.citrus

❖ White colony colony- S.albus/S.epidermis

❖ Non pigmented- S.Hyicus, S. intermedius

• Blood Agar-Sheep or Ox blood agar

✓Alpha-Narrow zone of complete haemolysis

 around colony

✓Beta-Wider zone incomplete/Partial haemolysis

 around colony

✓Gamma-No haemolysis

✓Delta- Complete haemolysis

(S. aureus & S. pseudointermedius produce both alpha &

Beta haemolysis; S.hyicus-Non haemolytic)

Double Haemolysis:- 

hot cold haemolysis phenomenon

Selective Medium

1. Baired parker agar- Black jet colony

 (Baird Parker Agar was developed by Baird Parker in 1962, coagulase positive

Staphylococci are capable of reducing tellurite to tellurium , which produces black colonies)

2. Mannitol Salt agar- Change medium from pink to

 yellow (S. aureus)

Mac-conkey agar-Can be grow and produce

 pink colour colony

Toxins and Virulence Factors