STAPHYLOCOCCAL INFECTIONS & DISEASES DR (MRS) M.B. FETUGA

Staphylococcus is an aerobic, non-sporulating, ubiquitous Gram positive bacteria. It is resistant to heat and drying hence may survive in non-physiologic environments for weeks and months. Clinically important species are Staphylococcus aureus (or pyogenes) and Staphylococcus epidermidis (or albus). DR (MRS) M.B. FETUGA

S. aureus which is coagulase positive is the most virulent species while S. epidermidis is coagulase negative and pathogenic only in immunocompromised states or in the presence of foreign bodies like catheters, cannulas or shunts. While S. aureus produces golden yellow pigment, S. epidermidis produces whitish pigment. DR (MRS) M.B. FETUGA

S. aureus also produces enzymes like ß – lactamase and staphylokinase and toxins like leucocidin, enterotoxins and fibrinolysins. The hallmark of S. aureus infection is extensive tissue destruction and pus formation. DR (MRS) M.B. FETUGA

SUSCEPTIBILITY Up to 50% of patients with Staphylococcal infections do not have underlying diseases. Colonization turns disease in the presence of: (1). Malnutrition (2). Diabetes mellitus (3). Chronic Liver Disease (4). Chronic Renal Failure (5). Congenital and acquired immune defects (6). leukaemias (7). Immunosuppressive therapy (8). HIV. Tissue damage (burns, eczema, herpetic infections and invasive procedures) usually precede staphylococcal infection. DR (MRS) M.B. FETUGA

EPIDEMIOLOGY 30% of healthy children carry S. aureus in their anterior nares. Other parts of the body usually colonized by S. aureus are the moist and warm parts like the axillae, groins and perineum. Spread usually occurs through the hands of hospital workers and carers who are carriers. Occasionally by airborne. Males are more affected than females. DR (MRS) M.B. FETUGA

CLINICAL FEATURES 1 These result from local suppuration, systemic dissemination and toxaemia. SKIN – Commonly pyoderma (folliculitis – infection of the superficial part of the hair follicle; furunculosis – infection of the deeper parts of the hair follicle; carbunculosis – infection of several hair follicles). Other cutaneous manifestations include impetigo contagiosa, bullous impetigo, ecthyma, pyonychia, scalded skin syndrome (positive nikolsky sign) and tropical pyomyositis. DR (MRS) M.B. FETUGA

CLINICAL FEATURES 2 RESPIRATORY SYSTEM – Otitis media, paranasal sinusitis, parotitis, tonsillitis and pharyngitis. Staphylococcal pneumonia may be primary or secondary (usually to a viral infection like measles). It is usually bronchopneumonia in type and may be complicated by pleural effusion, empyema thoracis, pneumatocoeles and pneumothoraces. DR (MRS) M.B. FETUGA

CLINICAL FEATURES 3 CARDIOVASCULAR – Endocarditis of native valves, myocardial abscess and purulent pericarditis. BONES AND JOINTS – Commonest cause of Osteomyelitis and suppurative arthritis. GASTROINTESTINAL TRACT - Food poisoning (caused by enterotoxins, usually presents with severe vomiting with or without diarrhoea within 2 to 6 hours of ingestion). DR (MRS) M.B. FETUGA

CLINICAL FEATURES 4 RENAL – renal and peri-nephric abscess. NERVOUS SYSTEM – Meningitis (following meningocoeles, dermal sinuses and in post-operative neurosurgical cases). SEPTICAEMIA – Carries high mortality and usually follows skin infection. NEONATAL AGE – Omphalitis, conjunctivitis and mastitis. DR (MRS) M.B. FETUGA

DIAGNOSIS Isolation from non-permissive sites (blood, CSF, skin lesions and abscesses) are usually the best. Isolates from skin surfaces (moist, warm and salty areas) and nose are not reliable as they may be normal commensals. Blood culture in septicaemia may only be positive in about a third of cases. Leucocytosis (with neutrophilia) and anaemia are usual. DR (MRS) M.B. FETUGA

MANAGEMENT 1 Topical antiseptics eg 5% chlorhexidine may be adequate for superficial skin lesions. systemic antibiotics are not recommended. Fluctuant skin abscesses should be incised and drained. Foreign bodies like tubes and catheters should be removed. DR (MRS) M.B. FETUGA

MANAGEMENT 2 Systemic therapy with penicillinase-resistant antibiotics: Cloxacillin 50 – 100mg/kg/day in 4 divided doses; Amoxycillin-Clavulanate 40 – 80 mg/kg/day in 3 divided doses Gentamicin 5mg/kg/day in 2 divided doses; Chloramphenicol 75mg/kg/day in 4 divided doses; Clindamycin 40mg/kg/day in 4 divided doses; Methicillin 150 – 200mg/kg/day in 4 divided doses; Vancomycin 40 – 60mg/kg/day in 4 divided doses; 1st generation Cephalosporins like Cephalexin 50 – 100mg/kg/day in 4 divided doses. DR (MRS) M.B. FETUGA

MANAGEMENT 3 AB should be given IV until fever has abated for at least 72 hours; then the oral forms can be substituted. However, the total duration of treatment for invasive diseases should be about 4 – 6 weeks unlike 1 week for most superficial infections. DR (MRS) M.B. FETUGA

MANAGEMENT 4 Current problem in Staphylococcal infections is about the Methicillin Resistant Staph. aureus (MRSA). Usually causes severe nosocomial infections and are resistant to most semi-synthetic penicillins containing the ß-lactam ring. Vancomycin or Ciprofloxacin may be employed to treat it. DR (MRS) M.B. FETUGA

PREVENTION Handwashing using detergents like chlorhexidine and hexachlorophene. Isolation of all persons with features suggestive of Staphylococcal disease in the hospital. DR (MRS) M.B. FETUGA