AUTHOR=Chen Jiawei , Chen Sheng , Jiang Yin , Zhang Rong , Cai Jiachang 

TITLE=Fecal Carriage and Genetic Characterization of CTX-M-1/9/1-Producing Escherichia coli From Healthy Humans in Hangzhou, China

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.616687

DOI=10.3389/fmicb.2021.616687

ISSN=1664-302X

ABSTRACT=<p>CTX-M-199, a novel chimeric β-lactamase which mediated resistance to sulbactam and tazobactam, was recently identified in Hangzhou, China. This study investigated the prevalence of fecal carriage of bacteria producing CTX-M-199 and other CTX-M-1/9/1-type enzymes among healthy individuals and characterized the genetic features of <italic>bla</italic><sub><italic>CTX–M–</italic>1/9/1</sub>-bearing mobile elements. A total of 74 Enterobacterales strains carrying various <italic>bla</italic><sub><italic>CTX–M–</italic>1/9/1</sub> genes, including <italic>bla</italic><sub><italic>CTX–M–</italic>64</sub> (<italic>n</italic> = 40, carriage rate of 0.74%), <italic>bla</italic><sub><italic>CTX–M–</italic>199</sub> (<italic>n</italic> = 23, 0.40%), <italic>bla</italic><sub><italic>CTX–M–</italic>123</sub> (<italic>n</italic> = 5, 0.10%), novel <italic>bla</italic><sub><italic>CTX–M–</italic>153</sub> (<italic>n</italic> = 5, 0.10%), and <italic>bla</italic><sub><italic>CT</italic><italic>X–M–</italic>132</sub> (<italic>n</italic> = 2, 0.04%), were isolated from 68 out of 5,000 (1.36%) fecal samples of healthy adults in Hangzhou City. Phylogenetic analysis based on whole-genome sequencing data showed that 72 <italic>bla</italic><sub><italic>CTX–M–</italic>1/9/1</sub>-bearing <italic>Escherichia coli</italic> isolates were clustered into four major clades, three of which included CTX-M-199 producers. Sixty out of 75 <italic>bla</italic><sub><italic>CTX–M</italic>–1/9/1</sub> genes were located on plasmids belonging to four Inc types: IncI2, IncI1, IncFIB, and IncHI2. The <italic>bla</italic><sub><italic>CTX–M–</italic>199</sub> genes were harbored by three of the four types of plasmids except for IncHI2. All these <italic>bla</italic><sub><italic>CTX–M–</italic>1/9/1</sub> genes were carried on an IS<italic>Ecp1</italic>-mediated transposition unit. In conclusion, human fecal carriage of <italic>bla</italic><sub><italic>CTX–M–</italic>1/9/1</sub> was low in healthy populations of China. The IS<italic>Ecp1</italic> was commonly associated with <italic>bla</italic><sub><italic>CTX–M–</italic>1/9/1</sub> and may mediate its transmission on various mobile elements. Our findings provide insights into the dissemination and the development of further measures for the control of pathogens producing CTX-M-1/9/1-type enzymes.</p>