Staphylococcus
Gram positive cocci
• Arrangement- In bunch / clusters (Grapes / Barry)
Coagulase positive for pathogenic
staphylococcus
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