Two-case cluster of rapidly progressive influenza B and Staphylococcus aureus pneumonia with one death

OBJECTIVES: To report a cluster of two epidemiologically linked construction workers with fulminant necrotizing pneumonia associated with co-infection by Panton-Valentine leukocidin (PVL)-positive methicillin-susceptible Staphylococcus aureus (MSSA) and influenza B virus. METHODS: Clinical characteristics, imaging findings, and microbiological results were retrospectively reviewed. Metagenomic next-generation sequencing (mNGS) was performed on sputum and bronchoalveolar lavage fluid after conventional diagnostic tests failed to identify the causative pathogens. RESULTS: Following shared occupational exposure, both patients developed severe pneumonia. One patient experienced rapid progression and died. For the second patient, mNGS successfully identified co-infection with PVL-positive sequence type 22 MSSA and influenza B virus, prompting a timely shift to targeted antimicrobial therapy that led to survival after prolonged intensive care. CONCLUSION: This report demonstrates the extreme virulence of PVL-positive MSSA-influenza co-infection, highlights the diagnostic value of mNGS in severe treatment-refractory pneumonia, and emphasizes the need for effective respiratory protection in high-risk occupational environments.