[The impact of antibiotic treatment in patients with influenza-like illness]

To study the etiology of influenza-like illness (ILI) in Beijing, and to investigate the impact of antibiotic treatment on outcomes.

This was a prospective cohort study. Patients with diagnosis of influenza-like illness were prospectively enrolled for study of bacterial and viral pathogens. Demographic characteristics, underlying diseases, respiratory and extrapulmonary symptoms, laboratory tests were also collected for analysis of relationship between drug therapy and outcomes.

A total of 476 cases were enrolled between Dec. 2006 and Apr. 2007, of whom 454 cases were used for analysis. Influenza virus was the most common pathogen( n = 197, 43.4%), with other pathogens rarely seen. The mean age of the patients was (33 +/- 13) years, and the ratio of male to female was 1.1:1. Twenty four patients (5.3% ) received influenza vaccine. The rate of antibiotic prescription after onset of illness was 63.4%, but none received antiviral drugs such as Oseltamivir and amantadine. Compared with influenza-negative patients, patients with influenza were older, had more underlying diseases and had greater severity of symptoms such as cough, sore throat, headache and myalgia (but with no statistical differences). The influenza syndrome (T > or = 39 degrees C plus cough, sore throat and headache or myalgia) was more common in the influenza group compared to the influenza-negative patients (P < 0.05). The ratio of antibiotic prescription was 67% in the influenza group, and the total white blood cell and platelet count, percentage of neutrophils were higher in antibiotic treatment patients compared with non-antibiotic treatment patients (P < 0.01). The cost in patients who received antibiotics was twice as much as non-antibiotic treatment patients (P < 0.05), but the defervescence time and respiratory symptom alleviation time did not differ. Cox regression analysis showed that the total white blood count and the differentials (OR value 1.049 and 1.014, respectively), but not antibiotic use were the independent risk factors for longer defervescence time.

Influenza virus was the most common pathogen for adult patients with ILI in Beijing city during the winter and the spring seasons. Antibiotic treatment of adult patients with ILI did not improve illness resolution, while the cost was increased significantly.