Frequency and effects of bacterial infection in children with influenza under oseltamivir treatment.

BACKGROUND

New antiviral drugs can rapidly improve the symptoms of influenza, but some patients still have prolonged fever and complications. The cause of the prolonged symptoms despite antiviral therapy remains unclear. Recent studies have shown a synergistic effect between influenza viruses and bacteria. This study investigated the frequency of bacterial infection in such patients and its effects on the clinical course to determine the need for antibiotics.

METHODS

In two seasons (December 2001 through March 2002, and December 2002 through March 2003), throat cultures were obtained from 387 patients with influenza being treated with oseltamivir, and clinical courses were observed. Control throat cultures were obtained from 109 healthy children.

RESULTS

The detection rate of pathogens was higher in patients with influenza (54.3%) than in control (23.9%, p<0.001). The most common pathogen was Streptococcus pneumoniae (49.7%) in patients with influenza and was Haemophilus influenzae (69.2%) in controls. Of the patients with normal flora, 4.1% had fever for 4 or more days and showed pathogens in throat cultures on day 4. Of the patients with pathogen-positive cultures who did not receive antibiotics, 40.3% had fever for 4 or more days.

CONCLUSION

Throat cultures obtained on the first or fourth day of treatment with oseltamivir were positive for pathogenic bacteria in all patients with fevers for 4 or more days. Our observations suggest that patients with influenza and prolonged fever despite receiving oseltamivir should be given antibiotics.