Background: Between 1986 and 1998, eight cases of community-acquired pneumonia due to Staphylococcus aureus strains carrying the gene for the Panton-Valentine leukocidin (PVL) were recorded in France, six of which were fatal. We aimed to assess the clinical features of these eight cases, and those of other cases identified prospectively, and to compare them with the characteristics of patients with pneumonia caused by PVL-negative strains.
Methods: We compared eight retrospective and eight prospective cases of PVL-positive S aureus pneumonia with 36 cases of PVL-negative S aureus pneumonia. For all patients, we recorded age, length of hospital stay, risk factors for infection, signs and symptoms, laboratory findings, antibiotic treatment, and serial radiological findings.
Findings: Median age was 14.8 years (IQR 5.4-24.0) for the PVL-positive patients and 70.1 years (59.2-81.4) for the others (p=0.001). Influenza-like illness had occurred during the 2 days before admission in 12 of the 16 PVL-positive patients, but in only three of 33 PVL-negative patients (p<0.001). PVL-positive infections were more often marked by: temperature greater than 39 degrees C (p=0.01), heart rate above 140 beats per min (p=0.02), haemoptysis (p=0.005), onset of pleural effusion during hospital stay (p=0.004), and leucopenia (p=0.001). The survival rate 48 h after admission was 63% for the PVL-positive patients and 94% for PVL-negative individuals (p=0.007). Histopathological examination of lungs at necropsy from three cases of necrotising pneumonia associated with PVL-positive S aureus showed extensive necrotic ulcerations of the tracheal and bronchial mucosa and massive haemorrhagic necrosis of interalveolar septa.
Interpretation: PVL-producing S aureus strains cause rapidly progressive, haemorrhagic, necrotising pneumonia, mainly in otherwise healthy children and young adults. The pneumonia is often preceded by influenza-like symptoms and has a high lethality rate.