Panton-Valentine leucocidin toxin
๐ About
- ๐ฆ Panton-Valentine Leucocidin (PVL) = pore-forming toxin produced by Staphylococcus aureus.
- ๐ฅ Destroys white blood cells โ extensive tissue necrosis.
- ๐ Found in <2% of S. aureus isolates, affecting both MSSA & MRSA strains.
โ ๏ธ Risks
- ๐๏ธ Overcrowding, institutions, poor hand hygiene.
- ๐ฉน Damaged skin (eczema, wounds).
- ๐ช Sharing personal items (razors, towels, gym equipment).
- ๐ IV drug use.
๐ฉบ Clinical Features
- ๐ Asymptomatic carriage possible.
- ๐ฉน Skin & soft tissue infection: boils (furuncles), carbuncles, abscesses.
- ๐ซ Necrotizing pneumonia: rapidly progressive, often in young/immunocompetent patients.
- Red flag signs โ haemoptysis, dyspnoea, hypotension, respiratory failure.
- High mortality despite therapy.
- ๐ Can cause leucopenia + very high CRP.
๐ Investigations
- ๐งซ Microscopy: Gram-positive cocci in clusters.
- ๐งช Culture & sensitivity โ confirms MSSA vs MRSA, guides antibiotics.
- ๐ฉธ FBC โ leucopenia (toxin-mediated).
- ๐ CRP markedly raised.
- ๐ฉป CXR โ cavitating infiltrates in necrotizing pneumonia.
๐ Management
- ๐ฅ Admit to ITU/HDU with isolation if pneumonitis present.
- ๐ Drain abscesses; send pus/blood for culture.
- ๐ Antibiotics (tailored with microbiology input):
- First-line โ Flucloxacillin (if MSSA).
- Alternatives โ Erythromycin, Clindamycin, Linezolid (esp. if MRSA suspected).
- ๐งโ๐ฌ Always involve microbiology early for PVL suspicion.
๐ก Exam tip: Think PVL if you see young, previously healthy patient with rapidly progressive pneumonia + haemoptysis.
Key differentiator: leucopenia with very high CRP.