Occurrence and characterization of oseltamivir-resistant influenza virus in children between 2007-2008 and 2008-2009 seasons / 소아과

PURPOSE: There was a global increase in the prevalence of oseltamivir-resistant influenza viruses during the 2007-2008 influenza season. This study was conducted to investigate the occurrence and characteristics of oseltamivir-resistant influenza viruses during the 2007-2008 and 2008-2009 influenza seasons among patients who were treated with oseltamivir (group A) and those that did not receive oseltamivir (group B). METHODS: A prospective study was conducted on 321 pediatric patients who were hospitalized because of influenza during the 2007-2008 and 2008-2009 influenza seasons. Drug resistance tests were conducted on influenza viruses isolated from 91 patients. RESULTS: There was no significant difference between the clinical characteristics of groups A and B during both seasons. Influenza A/H1N1, isolated from both groups A and B during the 2007-2008 and 2008-2009 periods, was not resistant to zanamivir. However, phenotypic analysis of the virus revealed a high oseltamivir IC50 range and that H275Y substitution of the neuraminidase (NA) gene and partial variation of the hemagglutinin (HA) gene did not affect its antigenicity to the HA vaccine even though group A had a shorter hospitalization duration and fewer lower respiratory tract complications than group B. In addition, there was no significant difference in the clinical manifestations between oseltamivir-susceptible and oseltamivir-resistant strains of influenza A/H1N1. CONCLUSION: Establishment of guidelines to efficiently treat influenza with oseltamivir, a commonly used drug for treating influenza in Korean pediatric patients, and a treatment strategy with a new therapeutic agent is required.

Oseltamivir efficacy, side effects, and safety in children with influenza / 소아과

PURPOSE: Although oseltamivir is widely used for treatment of influenza, few clinical studies of its efficacy and resistance have been performed in Korea. We evaluated the safety, side effects, and efficacy of oseltamivir treatment in Korean pediatric patients. METHODS: We analyzed 321 children diagnosed with influenza at Busan St. Mary's Medical Center, Korea, between January 2008 and June 2008 (first study period) and November 2008 and January 2009 (second study period). Patients were divided into two groups: those receiving oseltamivir treatment for 5 days and those receiving only symptomatic treatment. We investigated clinical symptoms, side effects, and resistance to oseltamivir. We also identified influenza strains and evaluated resistance to oseltamivir using an influenza virus culture. RESULTS: One hundred eighty-six patients were assigned to the treatment group, and 135 were assigned to the control group. The treatment group showed shorter admission duration (4.4 days) compared with controls (5.0 days) (P=0.000) and had fewer lower respiratory tract complications compared with controls (P<0.05). No significant statistical difference in the virus antigenic type was observed between the groups. In the first study period, virus culture showed influenza B (41.7% vs. 49.6%), A/H3N2 (7.9% vs. 8.4%), and A/H1N1 (9.4% vs. 6.5%). In the second study period, only A/H1N1 (55.3% vs. 50.0%) was isolated, except for one case of A (H3N2) in the treatment group. No differences in short- and long-term side effects, including neuropsychologic side effects, were noted between groups. There was no resistance to oseltamivir before or after treatment in the first study period. CONCLUSION: Based on our results, we suggest that osetalmivir therapy in pediatric patients is effective.