Necrotizing Pneumonia Caused by PVL-Negative Methicillin-Susceptible Staphylococcus aureus Complicated by Refractory Pneumothorax: A Case Report.

Methicillin-susceptible Staphylococcus aureus (MSSA) necrotizing pneumonia can progress to severe disease, particularly when Panton-Valentine leukocidin (PVL) is involved. Here we report the case of a previously healthy 56-year-old man who developed severe necrotizing pneumonia due to MSSA despite the absence of major toxin genes including PVL. The patient reported a 10-day history of low-grade fever and was admitted for bilateral pneumonia with sepsis. Despite antibiotic therapy, his condition rapidly progressed, and chest computed tomography revealed extensive ground-glass opacities and multiple cavitary lesions. MSSA was isolated from blood and pleural fluid cultures, and polymerase chain reaction confirmed negativity for PVL, toxic shock syndrome toxin-1, and exfoliative toxin genes. Although the infection improved with antibiotics including clindamycin, a potent toxin suppressor, the patient experienced recurrent refractory pneumothorax due to persistent cavitary lesions that led to prolonged respiratory failure. PVL-negative MSSA necrotizing pneumonia can be a life-threatening disease with long-term complications.