AUTHOR=Singh Nambram S. , Singhal Neelja , Virdi Jugsharan S. 

TITLE=Genetic Environment of blaTEM-1, blaCTX-M-15, blaCMY-42 and Characterization of Integrons of Escherichia coli Isolated From an Indian Urban Aquatic Environment

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.00382

DOI=10.3389/fmicb.2018.00382

ISSN=1664-302X

ABSTRACT=<p>The presence of antibiotic resistance genes (ARGs) including those expressing ESBLs and AmpC-β-lactamases in <italic>Escherichia coli</italic> inhabiting the aquatic environments is a serious health problem. The situation is further complicated by the fact that ARGs can be easily transferred among bacterial species with the help of mobile genetic elements – plasmids, integrons, insertion sequences (IS), and transposons. Therefore, the analysis of genetic environment and mobile genetic elements associated with ARGs is important as these provide useful information about the epidemiology of these genes. In our previous study, we had reported presence of various β-lactam resistance genes present in <italic>E. coli</italic> strains inhabiting the river Yamuna traversing the National Capital Territory of Delhi (India). In the present study, we have analyzed the genetic environment of three ARGs <italic>bla</italic><sub>TEM-1</sub>, <italic>bla</italic><sub>CTX-M-15</sub>, and <italic>bla</italic><sub>CMY -42</sub> of those <italic>E. coli</italic> strains. The structure of class 1 integrons and their gene cassettes was also analyzed. Insertion sequence IS<italic>26</italic> was present upstream of <italic>bla</italic><sub>TEM-1</sub>, IS<italic>Ecp1</italic> was present upstream of <italic>bla</italic><sub>CTXM-15</sub> gene and <italic>orf477</italic> was present downstream of <italic>bla</italic><sub>CTXM-15</sub>. IS<italic>Ecp1</italic> was also present upstream of <italic>bla</italic><sub>CMY -42</sub> and, <italic>blc</italic> and <italic>sugE</italic> genes were present in the downstream region of this gene. Thus, the overall genetic environment surrounding these genes was similar to that reported from <italic>E. coli</italic> strains isolated globally. Conjugation assays, isolation and analysis of plasmid DNA of the transconjugants indicated that <italic>bla</italic><sub>TEM-1</sub>, <italic>bla</italic><sub>CTX-M-15</sub>, <italic>bla</italic><sub>CMY -42</sub> and class 1 integron were plasmid-mediated and possibly transmit between genera through horizontal gene transfer (HGT). This might lead to dissemination of antimicrobial resistance genes in aquatic environment. The work embodied in this paper is the first describing the genetic environment of <italic>bla</italic> and integrons in aquatic <italic>E. coli</italic> isolated from India.</p>