Wastewater as a probable environmental reservoir of extended-spectrum β-lactamase genes: detection of chimeric β-lactamases CTX-M-64 and CTX-M-123.

This study focused on the Escherichia coli possessing bla CTX-M genes in wastewater inflows. Crude 12 inflow water samples from wastewater treatment plant (WWTP) A and two samples each from other three WWTPs were collected in 2017 and 2018. A total of 73 E. coli isolates with 31 different STs harboring distinctive bla CTX-M gene repertoires were detected. In WWTP A influents, the bla CTX-M-14 (14 isolates) was dominant, followed by bla CTX-M-15 (12 isolates), bla CTX-M-27 (10 isolates). The chimeric bla CTX-M-64 and bla CTX-M-123 were each identified in one of E. coli isolates from the same WWTP A inflow port. The bla CTX-M-27 was associated with five of seven B2-ST131 isolates including three isolates of the B2-O25b-ST131-H30R/non-Rx lineage. One of the remaining two isolates belonged to the B2-O25b-ST131-H30R/Rx lineage harboring bla CTX-M-15 As for the B2-O25b-ST131-H30R/non-Rx lineage, two isolates with bla CTX-M-27 were recovered from each of WWTPs B and D influents, and one isolate with bla CTX-M-174 was also from WWTP B influent. Whole-genome sequencing of chimeric bla CTX-M-harboring E. coli isolates revealed that the bla CTX-M-64 was integrated into the chromosome of ST10 E. coli B22 via ISEcp1-mediated transposition of 9,467-bp sequence. The bla CTX-M-123-carrying IncI1 plasmid pB64 was 109,169 bp in length with pST108. The overall findings suggest that wastewater may act as probable reservoir of clinically significant clonal lineages mediating antimicrobial resista...

Source: Applied and Environmental Microbiology - September 12, 2019 Category: Microbiology Authors: Tanaka H, Hayashi W, Iimura M, Taniguchi Y, Soga E, Matsuo N, Kawamura K, Arakawa Y, Nagano Y, Nagano N Tags: Appl Environ Microbiol Source Type: research