The impacts of bacterial co-infections and secondary bacterial infections on patients with severe influenza pneumonitis admitted to the intensive care units.

PURPOSES:This study investigated the prevalence and clinical outcomes of pulmonary bacterial co-infections and secondary bacterial infections in patients with severe influenza pneumonitis. METHODS:We retrospectively analyzed the data of adult patients with severe influenza pneumonitis admitted to medical ICUs. Bacterial co-infections and secondary bacterial infections were identified. The risk factors of bacterial infection were evaluated. The outcomes of patients regarding co-infection or secondary bacterial infection were analyzed. RESULTS:We identified 117 critically ill patients with laboratory-confirmed influenza pneumonitis admitted to the medical ICUs. Klebsiella pneumoniae (31.4%) and Staphylococcus aureus (22.8%) were the most identified bacteria in patients with bacterial co-infection. A high proportion of methicillin-resistant Staphylococcus aureus (17.1%) was noted. Liver cirrhosis and diabetes mellitus were the independent risk factors for bacterial co-infection. Acinetobacter baumannii (30.7%) and S. aureus (23.1%) were the most often identified bacteria in patients with secondary bacterial pneumonia. Patients with secondary bacterial infections had a longer duration of mechanical ventilation, and longer ICU and hospital stay. CONCLUSIONS:High rates of drug-resistant bacterial co-infections and secondary bacterial infections were identified in patients with severe influenza pneumonitis requiring ICU care and were associated with more morbidity in these patients.