Lecture 1 Staphylococcus aureus
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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.
Lecture 1 Staphylococcus aureus
- 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.
- 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.