The use of topical antibiotics based on National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB) Open Data in 2017.

The national action plan on antimicrobial resistance (AMR) in Japan emphasizes the importance of understanding antimicrobial use (AMU). Some studies have been conducted on oral and parenteral AMU in Japan. However, there are few studies on the use of topical antimicrobials, such as in dermatology and ophthalmology. Therefore, the purpose of this study was to investigate topical AMU in Japan. Data on AMU in dermatology and ophthalmology were obtained from the 2017 National Database of Health Insurance Claims and Specific Health Checkups of Japan Open Data. The number of dermatological products used was 58,396,530 in 2017. The proportion of betamethasone/gentamicin was 50.5% and that of gentamicin 16.7%, whereas that of the ingredient quantity in gentamicin was 7.8%. It was suggested that topical AMU should be evaluated by the number of products. The number of ophthalmological products used was 24,655,653 in 2017, and the proportion of quinolones was 95.9%. The high prescription rate of quinolones may cause an increase in quinolone resistance in the ophthalmologic field. Topical AMU, which is a potential "blind spot" in the measures against AMR, needs to be continuously monitored, together with systemic AMU.