2473. Trends in Methicillin Resistance Rate of Staphylococcus aureus among Medical Facilities Participating in Japan Nosocomial Infections Surveillance (JANIS)

BACKGROUND: The medical fee revision in 2014 economically motivated hospitals to join surveillance programs, such as Japan Nosocomial Infections Surveillance (JANIS), and rapidly increased JANIS member hospitals. The characteristics of the newly joined hospitals might have affected the reported resistance rate trends regardless of the effect of the policy itself. We examined the effect of the hospitals joining JANIS after 2014 on the trends in methicillin resistance rate of S. aureus. METHODS: We analyzed annual trends in methicillin resistance rate of S. aureus among inpatients, using JANIS datasets of 2007 to 2016, and defined oxacillin- or cefoxitin-resistant S. aureus as methicillin resistant. The dataset consisted of a total of 7,105 hospitals and 2,740,750 S. aureus test results. Hospitals were divided into two groups; joining JANIS A) before 2014 (751 hospitals), B) in and after 2014 (781 hospitals). A probit model examined their characteristics, and a panel data analysis calculated the resistance rate trends adjusted for age and sex, including interaction terms of hospitals group and year. Finally, we divided patients into quintile age groups, and conducted the same analysis by sex. RESULTS: The methicillin resistance rate of S. aureus decreased from 59.4% (2007) to 48.6% (2016), and the decreasing trend kept significant through the study period but 2009 (mean annual decrease: 1.2%, P < 0.05). Inpatients of hospital B had higher age (β = 0.01, P < 0.001), and more male (β = 0.005, P < 0.05), but their resistance rate was not significantly higher (β = 0.05, p = 0.12) compared with hospital A. Age stratified analysis for all hospitals found the youngest group (younger than 35 years old) of both sex had steadily low resistance rates through the period, while the older groups had higher rates, but their rates decreased continuously. CONCLUSION: The methicillin resistance rates of S. aureus decreased throughout 2007 to 2016 except 2009. The patients of the hospitals newly joining JANIS were higher in age, but the resistance rate of S. aureus was not statistically different from the hospitals having joined JANIS before 2014. Also, among JANIS member hospitals, older patients had higher resistance rates than younger patients, but their rates were continuously decreasing. DISCLOSURES: All authors: No reported disclosures.