Comparison of community-acquired pneumonia due to methicillin-resistant and methicillin-susceptible Staphylococcus aureus producing the Panton-Valentine leukocidin

OBJECTIVE: To investigate the clinical features and prognosis of patients with methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) community-acquired pneumonia (CAP) producing the Panton-Valentine leukocidin (PVL). METHODS: PubMed and Scopus were searched. Inclusion was stratified according to S. aureus susceptibility and clinical, microbiological and outcome data of patients with S. aureus CAP; both primary and secondary cases of CAP (hematogenous spread from other sites of infection) were included. RESULTS: We identified 71 articles reporting data on patients with MRSA (n = 76) and MSSA (n = 31) PVL-positive CAP. There were no differences in demographics and history among patients with MRSA and MSSA CAP. Features associated with MRSA CAP were gastrointestinal tract symptoms (P = 0.016) and unilobar infiltrates (P = 0.043). Features associated with MSSA CAP were airway hemorrhage (P = 0.01), multilobar in-filtrates (P = 0.043) and acute respiratory distress syndrome (ARDS, P = 0.023). Although MSSA patients were more likely to receive initial appropriate antimicrobial therapy (P < 0.001), there was no difference in mortality between the two groups (P = 0.919). Univariate analysis showed that influenza-like symptoms (P < 0.001), multi-organ failure (P < 0.001.), admission to the intensive care unit (P < 0.001), mechanical ventilation (P < 0.001), leucopenia (P < 0.001), shock (P = 0.001), development of complications (P = 0.003), vein thrombosis (P < 0.001), disseminated intravascular coagulation (P = 0.03), acidosis (P = 0.012), rash (P = 0.024), ARDS (P = 0.021), necrotizing pneumonia (P = 0.026), and use of macrolides after culture results (P = 0.011) were factors associated with death. CONCLUSIONS: Patients with MRSA PVL-positive CAP did not have higher rates of mortality than patients with MSSA PVL-positive CAP.