First Report of Extended-Spectrum Betalactamase-Producing Klebsiella pneumoniae Among Fecal Carriage in Iran: High Diversity of Clonal Relatedness and Virulence Factor Profiles

Abstract

Increasing rate of silent intestinal carriers with extended-spectrum betalactamase (ESBL)-producing Klebsiella pneumonia (ESBL-KP) has given rise to a serious healthcare problem in clinical settings. Various epidemiological studies are being conducted to determine clonal relatedness among carriers. In this study, we investigated the intestinal carriage of ESBL-KP and clonal relatedness among ESBL-KP isolated from fecal carriage in Iran for the first time. A total of 120 rectal swabs (RSs) were collected including 61 from inpatients of intensive care unit and 59 from outpatients. ESBL-KP screening was performed using MacConkey agar supplemented with cefotaxime. PCR was done for detection of ESBL, carbapenemase, and virulence factor genes. Conjugation experiments and PCR-based replicon typing were performed. Clonal relatedness was investigated by multilocus sequence typing (MLST) and multiple locus variable number tandem repeat analysis (MLVA). Out of a total of 120 RSs, 18.3% (22/120) ESBL-KP were isolated. The rate of bla_CTXM-15 was 81%. ompk35 was the most prevalent virulence gene detected in 86.3% of the isolates. In conjugation experiments, three out of five tested isolates had conjugative plasmids. The most prevalent plasmid types belonged to IncL/M, IncA/C, and Inc FII. The MLST analysis showed that the main sequence types (STs) identified among ESBL-KP isolates were ST147, ST15, and ST16. The isolates were characterized into 4 miniclusters and 11 singletons using MLVA. High heterogeneity among ESBL-KP isolates indicated that this bacterium could be colonized in different sites and easily transferred. Screening of carriers in hospitals and community could help in controlling of infection in the healthcare and community settings.

Keywords: Klebsiella pneumoniae; clonal relatedness; fecal carriage.