Staphylococcus aureus (Gram-positive cocci).pptx

Staphylococcus aureus is one of the most important bacteria in medical microbiology. In this video, we explain its characteristics, morphology, virulence factors, diseases, diagnosis, and treatment in a clear and simple way.

1. Staphylococcus aureus By Syed Ismail

2. Morphology : Shape : It is spherical in shape (cocci) Arrangement : Cocci are arranged in grape-like irregular clusters. Capsule : Some strains are capsulated. Motility : Non-motile. Spore : Non-spore forming

3. Staining: Gram’ s st aining : G ram-positive (violet color) Pathogenesis and Clinical Findings: Localized infections : Acne and pimples. Furuncle (hair follicle infection) (Redness, Swelling, Severe Pai n) Carbuncle. Impetigo. (Blisters on the Face, Neck, and Hands) Bacteremia Food poisoning (Nausea, Vomiting, Severe abdominal Cramp, Headache)

4. Diagnostic Laboratory Tests: Specimen : Surface swab, pus, blood, tracheal aspirate, CSF. Microscopy : Gram stained smear of specimen is seen under microscope. Culture : Specimens are cultured on nutrient agar, blood agar and on selective media ( Mannitol salt agar containing 7.5% NaCl )

5. CULTURE : Media (1) Nutrient agar (2) Blood agar (3) Selective medium

6. TREATMENT : Antimicrobial drugs : Ce fazolin N afcillin O xacillin V ancomycin D aptomycin and L inezolid

7. Prevention and Control: (1) No effective immunization with toxoid or vaccines. (2) Cleanliness, eg. frequent hand washing. (3) Aseptic management of lesions. (4) Dissemination from nose or skin of carriers can-be reduced by topical application of antimicrobial agents, eg chlorhexidine or bacitracin cream.

8. HABITAT & TRANSMISSION : S aureus : Nasal carriage in 40-50% human beings. Found regularly on clothing, bed linens and other fomites of human environment.