U Kastner1, J P Guggenbichler. 1. University Clinic for Pediatric and Adolescent Patients, Dept. of Pediatric Infectious Diseases, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany.
Abstract
BACKGROUND: The long elimination half-life of azithromycin allows subinhibitory serum and epithelial lining fluid (ELF) concentrations over a period of several weeks post treatment, which may have an impact on the emergence of macrolide resistance. In this prospective, open-label, randomized study, four macrolides and the azalide azithromycin were studied for their likelihood to promote resistance in the oral flora of children with respiratory tract infections. PATIENTS AND METHODS: Children were randomly assigned to receive azithromycin, clarithromycin, erythromycin, roxithromycin and josamycin. Throat swabs were obtained prior to treatment and weekly for 6 weeks. Minimum inhibitory concentrations (MICs) for resistant strains were assessed by E-test and National Committee for Clinical laboratory Standards (NCClS) broth microdilution. RESULTS: One week post treatment, up to 90% of children harbored macrolide-resistant strains in their oral flora. Except for azithromycin, the percentage of patients colonized by resistant organisms decreased to a rate of 17% for clarithromycin (10/60), erythromycin (2/12) and josamycin (2/12) and 33% for roxithromycin (4/12) after 6 weeks. In the azithromycin group, 85% (51/60) of patients were colonized by macrolide-resistant organisms after 6 weeks, 11.6% (7/60) of children suffered from reinfection. CONCLUSION:Azithromycin therapy appears to put selective pressure on the infective and native flora of children, promoting the carriage of macrolide-resistant strains.
RCT Entities:
BACKGROUND: The long elimination half-life of azithromycin allows subinhibitory serum and epithelial lining fluid (ELF) concentrations over a period of several weeks post treatment, which may have an impact on the emergence of macrolide resistance. In this prospective, open-label, randomized study, four macrolides and the azalideazithromycin were studied for their likelihood to promote resistance in the oral flora of children with respiratory tract infections. PATIENTS AND METHODS: Children were randomly assigned to receive azithromycin, clarithromycin, erythromycin, roxithromycin and josamycin. Throat swabs were obtained prior to treatment and weekly for 6 weeks. Minimum inhibitory concentrations (MICs) for resistant strains were assessed by E-test and National Committee for Clinical laboratory Standards (NCClS) broth microdilution. RESULTS: One week post treatment, up to 90% of children harbored macrolide-resistant strains in their oral flora. Except for azithromycin, the percentage of patients colonized by resistant organisms decreased to a rate of 17% for clarithromycin (10/60), erythromycin (2/12) and josamycin (2/12) and 33% for roxithromycin (4/12) after 6 weeks. In the azithromycin group, 85% (51/60) of patients were colonized by macrolide-resistant organisms after 6 weeks, 11.6% (7/60) of children suffered from reinfection. CONCLUSION:Azithromycin therapy appears to put selective pressure on the infective and native flora of children, promoting the carriage of macrolide-resistant strains.
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