Lecture 1 Staphylococcus aureus

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Lecture 1 Staphylococcus aureus

  1. 1. ‫بسم ا الرحمن الرحيم‬ GENUS: STAPHYLOCOCCUS Prof. Khalifa Sifaw Ghenghesh
  2. 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
  3. 3. Scanning electron micrograph of Staphylococcus aureus
  4. 4. _________________________________ Species Production of Coagulase ------------------------------------------------------S. aureus + S. epidermidis -S. saprophyticus -_________________________________
  5. 5. 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.
  6. 6. Libya A B C AB BC Negative 2.5 27.5 40.0 2.5 7.5 0.0 20.0
  7. 7. 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
  8. 8. 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
  9. 9. Sputum smear shows Staphylococcus aureus in a patient with staphylococcal pneumonia
  10. 10. 7. Food Poisoning: 8. Toxic Shock Syndrome: > Fever, Hypotension>> Multisystem Involvement.
  11. 11. 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:
  12. 12. NA, BA, Milk Agar or MSA Observe Colonial Morphology Gram Stain Catalase Test Slide or Tube Coagulase Test
  13. 13. 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.
  14. 14. 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.

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