Clinical Analysis of Influenza A (H1N1) Viral Pneumonia Complicated with Bacterial Infection

Abstract

Purpose: We investigated the efficacy of potent or combined antibiotics in patients suffering bacterial infections secondary to H1N1 by retrospectively analyzing their bacterial pathogen spectrum and clinical characteristics. Methods: Multi-center retrospective analysis was performed using clinical data of H1N1 patients from 27 hospitals in Hebei Province, China, from November 1 to December 31, 2009. Results: Of 480 H1N1-infected patients enrolled from an inpatient clinic, 91 were positive for bacterial culture. Bacteria were detected in sputum culture at 7.00 ± 8.87 days post-admission. Compared with the negative group, the patients in the positive sputum culture group had a higher mean age and prevalence of basic diseases, higher APECHEII (Acute Physiology and Chronic Health Evaluation II) score within 24 hours of admission, longer hospital stays, and higher mortality. In total, 189 bacterial strains were isolated, with the majority of samples testing positive for Acinetobacter baumanii (47), Streptococcus viridians (26), or Pseudomonas aeruginosa (19). S. viridians was the major cause of infection within 3 days of admission, while A. baumanii infection was more prevalent from 4 days post-admission; there was a significant difference in the constituent ratio between the two pathogens (p 0.001). Compared with patients administered common antibiotics, the potent antibiotics group showed no significant difference in hospitalization time, time until bacterial detection, mortality, or detection ratio of resistant strains (p > 0.05). Conclusions: Complicated bacterial infection in H1N1 patients increases hospitalization time and mortality. Gram-negative bacilli and multi-resistant strains are the main sources of infection. Early administration of potent or combined antibiotics, even during the period of rapid onset, may not be suitable in H1N1-infected patients, particularly previously healthy young patients.