Lecture 1 Staphylococcus aureus

1. ميحرلانمحرلاامسب
GENUS:
STAPHYLOCOCCUS
Prof. Khalifa Sifaw Ghenghesh

2. 1 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)

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. a - Toxin:
> Cytotoxic Effects:
> Necrosis of Skin and Haemolysis.

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

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 b-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.