CTX-M Group Distribution and Positivity of Extended-Spectrum β-Lactamase (ESBL)-Producing Enterobacteriaceae in Urinary Tract Infections in a Tertiary Metropolitan Hospital in Japan

Abstract

Urinary tract infection (UTI) is one of the most common clinical diagnoses managed by primary care physicians both in outpatient and inpatient care. The increasing ratio of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) among UTI-causing pathogens is an epidemiological concern both in Japan and worldwide, leading to a higher empirical usage of broad-spectrum antibiotics. Commercially available genotypic diagnostic technologies for ESBL-E have been incorporated in clinical settings to facilitate earlier de-escalation to narrow-spectrum antibiotics. However, genotypic testing can detect only certain genotypes of the ESBL (CTX-M) group, and there are insufficient data regarding the ratio of other ESBL genotypes (TEM, SHV), especially in severe UTI cases. In this study, we collected consecutive ESBL-E isolates from UTI cases that fulfilled the systemic inflammatory response syndrome (SIRS) criteria from June 2012 to July 2017 in a tertiary metropolitan hospital in Japan and evaluated their genotypic distribution. Among 36 isolates, the number of cases with genotypes CTX-M-1, CTX-M-2, CTX-M-9, SHV, and TEM were 12, 4, 21, 1, and 14, respectively. Notably, all isolates with SHV and/or TEM genotypes concomitantly had one of the CTX-M genotypes, and there were no ESBL-E isolates that harbored only SHV or TEM. Further research is warranted to investigate the utility of commercially available genotypic diagnostic technologies for ESBL-E in the clinical setting.