Staphylococcus

1. Staphylococcus
Dr. Kanwal Deep Singh Lyall
M.D. Microbiology

2. • Staphyle = Bunch of grapes
• Kokos = berry
• GPC in cluseter
• Common cause of suppuration
• Sir Alexander Ogston (1880) – Scottish
surgeon established role in pus formation
• Rosenbach – S. aureus, S. albus
• Passet – S. citrus

3. Staphylococcus
Coagulase
Positive Negative
S. Aureus CoNs
S. Epidermidis
S. Hemolyticus
S. Saprophyticus
S. Intermedius

4. S. Aureus
• GPC in clusters , 1µm , non-motiles, non-
sporing
• Divide in 3 perpendicluar planes – daughter
cells remain in close proximity
• Pigment : golden yellow, non-diffuseble,
carotenoid, best seen at 22 – 25 C, aerobic con
• ↑ed by 1% Glc. Monoacetate, milk
• Grows on BA, MA, NA, MSA (selective)

5. Resistance
• Hardy organisms
• Survives in dried pus x 2 – 3 mnths
• Killed @ 62 C x 30 M
• Tolerates 10% NaCl
• Crystal violet (1:500000)
• Brilliant green (1:10 million)
Lethal

6. Antigenic structure (CPTP)
• Capsule: polysaccharide – virulence
• Peptidoglycan: rigidity, complement
activation, cytokine production
• Teichoic acid: major Ag, adhesions & inhib of
opsonisation
• Protein A: chemotactic, antiphagocytic, anti-
complementary, Cowan – 1 strain, binds IgG,
Used for coaglutination

7. Toxins & Enzymes
• Toxins (HLETEx)
• Hemolysins
• Leucocidens
• Enterotoxins
• TSST
• Exfloiative toxin
• Coagulase
• Clumping factor
• DNAse
• Phosphatase

8. Toxins
• Hemolysins – alpha, beta, gamma, delta
– Alpha lysin – in aerobic cond., protein, inactivates @
60 C, Reactivates @ 80 - 100 C – cytotoxic,
leucotoxic, dermonecrotic
– Beta lysin – lysis activated @ 37, evident on cooling
• Leucocidin – PVL, slow & fast components – damages
PMNs & Macrophages
• Enyterotoxins – A(m/c) BC1,2,3,DEH (8) – food
poisoning, nausea, vomiting, diarrhea with 6 – 8 hrs ,
resist boiling x 30 m, active in minute quantities,
autonomic nervous system

10. • TSST – t , BP, vomitings, diarhoea,, rash,
deaquamation, hyperemia, tampoon users
• Exfoliative toxin: SSSS, Rieter’s disases
– Toxin A : heat stable, chromosome coded
– Toxin B: heat labile, plasmid coded

11. Coagulase
• 8 types (A-H)
• clots human/rabbit
plasma
• Secrerated free
• Heat labile
• Requires CRF
• Dosent clot GP plasma
• Fibrinogen fibrin
• Tube test
• Requires incubation
Clumping factor
• One type
• Clumping of cocci
• Bound to CW
• Heat stable
• Precipitation of fibrin on
cell surface
• Slide test
• Immediate results

12. Pathogenesis
• Cutaneous infections
• Pyogenic infections
• Respiratory infections
• Deep seated infections
• Food poisoning
• Nosocomial infections
• Exfoliative infections
• TSST
• SSSS

13. Lab diagnosis
Sample
Gram stain Culture – BA/GB/BB/MSA
BACTEC
37 C x 18 – 24 hrs
Colonies
GS & Biochemical reactions
Phage typing AST

14. S. aureus S. epidermidis

15. Biochemical reactions
• Catalase + , coagulase +, ferments mannitol,
liquifies gelatin, produces phosphatase,DNAse
• NA + Phen. Pthal. Diphos. Free
phosphatase ammonia vapours Pink
• Urease +, Indole production – ve , MR,VP +
• Nitrate +ve

17. MRSA
• Penicillinase – plasmid coded
• PBP2 – Chromosome coded (mecA gene)
• Resistant to all beta lactams, beta lactam +
beta latamase inhb., monobactams

18. CoNS
• S. epidermidis - Opportunistic infections
• S. saprophyticus – UTI in sexually active females,
resistant to Novobiocin (5µg,< 12mm)
• Micrococci:
 Modified oxidase positive
 In Hugh leefson test – oxidative
 Tetrads
 Larger ( > 1 mm)
 White , small colonies