Staph Infections: Transmission, Risk Factors, and Prevention

Staphylococcus aureus ("staph") is a common bacterium colonizing the skin and nares of ~30% of healthy people. Most colonization is harmless, but breach of skin barrier or immune compromise can lead to infection.

Common Acquisition Routes

1. Skin and Soft Tissue Entry

• Cuts, abrasions, lacerations, burns, insect bites, surgical incisions
• Folliculitis → furuncles (boils) → carbuncles → abscesses
• Impetigo (superficial, contagious, common in children)
• Cellulitis (spreading dermal infection)

2. Medical Device–Associated

• Central lines, urinary catheters, prosthetic joints, cardiac devices, dialysis access
• Biofilm formation on device surfaces → resistant to antibiotics and immune clearance
• Major cause of healthcare-associated infections (HAIs)

3. Person-to-Person Transmission

• Direct contact with infected wound drainage
• Contaminated hands of healthcare workers (key in hospitals)
• Household spread (sharing towels, razors, bedding)
• Sports: skin-to-skin contact (wrestling, football), shared equipment

4. Community Risk Factors

• Crowded living conditions (military, prisons, dorms, shelters)
• Poor hygiene, inadequate wound care
• Skin conditions (eczema, psoriasis) with barrier disruption
• Injection drug use
• Men who have sex with men (MSM) — higher CA-MRSA rates

Methicillin-Resistant S. aureus (MRSA)

• HA-MRSA: Healthcare-associated; multidrug resistant.
• CA-MRSA: Community-associated; often Panton-Valentine leukocidin (PVL)+; causes severe skin/soft tissue infections, necrotizing pneumonia. Susceptible to more oral agents (TMP-SMX, doxycycline, clindamycin).

Prevention

• Hand hygiene: Alcohol-based rub or soap/water — #1 intervention.
• Wound care: Clean, cover, monitor for infection signs.
• Decolonization (targeted): Intranasal mupirocin + chlorhexidine baths for high-risk (pre-op, recurrent infections, outbreak control).
• Device bundles: Sterile insertion, chlorhexidine maintenance, prompt removal.
• Personal items: Don't share towels, razors, uniforms, equipment.
• Environmental cleaning: High-touch surfaces in healthcare/gyms.

When to Seek Care

• Red, swollen, painful, warm skin lesion + fever
• Rapidly expanding redness, red streaks
• Abscess (fluctuant, purulent)
• Non-healing wound
• Immunocompromised patients with any skin infection

Treatment: Incision & drainage (abscesses) + targeted antibiotics (culture-guided). Never squeeze or self-drain abscesses.