This document discusses Staphylococcus, including S. aureus. It notes that Staphylococcus is a facultative anaerobic, gram-positive coccus that forms grape-like clusters. It distinguishes between coagulase-positive and coagulase-negative species. S. aureus is described as the most virulent species, producing toxins and enzymes that can cause infections like impetigo, pneumonia, toxic shock syndrome, and food poisoning. Laboratory diagnosis and treatments like antibiotics are also summarized.

1. ‫بسم ا الرحمن الرحيم‬
GENUS:
STAPHYLOCOCCUS
Prof. Khalifa Sifaw Ghenghesh

2. STAPHYLOCOCCUS
Facultative Anaerobic, Gram +ve
Cocci, Non-motile, Non-sporing,
Arranged in Grape-like Clustures.
Catalase:
1. Coagulase Positive Staphylococci
(CPS)
2. Coagulase Negative Staphylococci
(CNS)
1
2

4. Scanning electron micrograph of
Staphylococcus aureus

5. _________________________________
Species
Production of
Coagulase
------------------------------------------------------S. aureus
+
S. epidermidis
-S. saprophyticus
-_________________________________

6. Staphylococcus aureus
VIRULENCE FACTORS
1. Protein A:
> A Major Protien in the Cell Wall
2. Enterotoxins:
> Immunologic Types A-E.
3. α - Toxin:
> Cytotoxic Effects:
> Necrosis of Skin and Haemolysis.

7. Libya
A
B
C
AB
BC
Negative
2.5
27.5
40.0
2.5
7.5
0.0
20.0

8. 4. Epidermolytic Toxins:
> Impetigo and Scalded-Skin Syndrome.
5. Toxic-Shock Syndrome Toxin (TSST-1):
> Toxic Shock in Tampon Using Menstruating
Women.
6. Enzymes:
i. Coagulase
ii. Fibrinolysin
iii. Hyaluronidase
iv. Lipase

9. CLINICAL INFECTION
1. Skin Infections:
> Impetigo, Furuncles, Cellulitis, Surgical and
Wound Infections and Postpartum Breast
Infections.
2. Bacteraemia:
>From Localized Lesions
3. Endocarditis:
4. Osteomyelitis:
5. Pneumonia:
6. Abscesses (metastatic):
> In any Organ

10. Sputum smear shows Staphylococcus aureus in a
patient with staphylococcal pneumonia

11. 7. Food Poisoning:
8. Toxic Shock Syndrome:
> Fever, Hypotension>> Multisystem
Involvement.

12. LAB. DIAGNOSIS:
Specimens:
i. Pus: From Abscesses, Wounds, Burns, Etc..
ii. Sputum:
iii. Faeces:
iv. Blood:
v. Mid-Stream Urine:
> Suspected Cystitis, Pyelonephritis or Post
Catheterization Infection.
vi. Anterior Nasal and Perineal Swabs:

13. NA, BA, Milk
Agar or MSA
Observe Colonial
Morphology
Gram Stain
Catalase Test
Slide or Tube
Coagulase Test

14. PHAGE TYPING
> For Epidemiological Studies.
TREATMENT
i. Production of β-Lactamase> Resistance to
Penicillins.
ii. Penicillins Stable to Staphylococcal Penicillinase:
> Methicillin, Cloxacillin and Flucloxacillin.
iii. Other Antibiotics:
iv. MRSA >>> Vancomycin.

15. EPIDEMIOLOGY:
1. Sources of Infection:
i. Infected Lesions:
> Doctors and Nurses.
> Foodhandlers.
ii. Healthy Carriers:
iii. Animals:
> Domesticated and Some Wild Animals:
2. Modes of Infection:
– Exogenous
– Endogenous
Cross Infections:
> Important in Hospitals >> by Direct Contact.