A trend in prevalence of antimicrobial use and appropriateness of antimicrobial therapy in an acute care hospital from 2018 to 2019: repeated prevalence surveys in Japan.

In the 2019 survey, a total of 275 patients were included, and 256 patients were included in the 2018 survey. The prevalence of antimicrobial drug use did not change from 2018 to 2019 (28.5% versus 28.7%; p = 0.96). The proportion of cefazolin in all antimicrobial drugs used on the survey date significantly decreased from 2018 to 2019 (24.1% versus 0.0%; p < 0.001). The proportion of appropriate antimicrobial use in all antimicrobial therapies tended to be lower in 2019 than in 2018 (41.2% versus 60.6%; p = 0.06), and the proportion of unnecessary use of a broader spectrum of antimicrobial drugs significantly increased from 2018 to 2019 (4.7% versus 37.3%; p = 0.002). The shortage of cefazolin might lead to inappropriate use of other antimicrobial drugs.