Staphylococcal Infection

Staphylococcal infection is a pyogenic disease caused by Gram-positive staphylococci: pathogenic S. aureus, opportunistic S. epidermidis, and S. saprophyticus. S. aureus produces many exotoxins/enzymes causing skin/soft-tissue infection and severe septicemia, endocarditis, pneumonia, meningitis, foreign-body infection, UTI, osteomyelitis, arthritis, and enteritis.

Common Symptoms

Mastoiditis; pericarditis; septicemia; bacterial endocarditis; meningitis

Causes and Pathogenesis

(1) Hemolysins: α/β/γ/δ, all causing complete hemolysis; α also damages platelets/macrophages/WBCs and contracts vascular smooth muscle causing ischemia. (2) Leukocidin kills WBCs/macrophages allowing intracellular survival. (3) Enterotoxins A/B/C1/C2/D/E cause food poisoning. (4) Epidermolytic toxin causes staphylococcal scalded skin syndrome. (5) TSST. (6) Erythrogenic toxin from phage group II type 71 causes scarlet fever-like rash. Enzymes: (1) coagulase (fibrin deposition, antiphagocytic, thrombus formation); (2) β-lactamase; (3) hyaluronidase (spread); (4) lipases; (5) staphylokinase/catalase/fibrinolysin. Antigens: capsule; protein A (binds IgG Fc, antiphagocytic); wall teichoic acid. Virulence regulation is complex (agr/sar genes). Resistance: ~90% of clinical staphylococci in Beijing/Shanghai are penicillin-resistant (β-lactamase); MRSA (mecA/PBP2a) is resistant to all β-lactams, with >50% gentamicin resistance and >80% fluoroquinolone resistance; VISA (MIC 8-16 µg/ml) first reported 1996; rare VRSA abroad. MRSE is similarly resistant. Mechanisms: inactivating enzymes, target modification (PBP2a, DNA gyrase/topoisomerase IV), efflux. Pathogenesis: S. aureus is normally a commensal; severe disease requires immunocompromise (neutropenia, comorbidity) or barrier breaks (wounds, devices), leading to local abscesses, cellulitis, wound infection, bacteremia, endocarditis, osteomyelitis, renal carbuncle, septic arthritis, epidural abscess. Toxins cause TSS, SSSS, and enterotoxin gastroenteritis; superantigens (TSST-1, SEs) release IL-1/IL-6/IL-8/TNF-α causing SIRS and shock. Coagulase-negative staphylococci are opportunists related to foreign bodies (catheters, prostheses) and glycocalyx-mediated adherence.

Treatment

Traditional Chinese medicine, supportive therapy

Preventive Measures

1. Industrial skin protection; avoid trauma. 2. Treat cases/carriers. 3. Strict isolation in nurseries/burn/surgical wards. 4. Control chronic diseases (diabetes, hematologic disease, cirrhosis) and correct immunodeficiency. Antistaphylococcal vaccines may improve phagocytosis and survival.

Department to Visit

It is recommended to visit the Infectious Diseases department; an appointment can be booked on this platform before the visit.

Warm reminder: The above information is for health science reference only and cannot replace professional medical diagnosis. If you have related symptoms, please seek medical attention at a regular hospital promptly.