Genetic contexts related to the diffusion of plasmid-mediated CTX-M-55 extended-spectrum beta-lactamase isolated from Enterobacteriaceae in China

Abstract

BackgroundCTX-M-55 extended-spectrum beta-lactamases are being rapidly disseminated and transmitted in clinical practices around the world. The genetic contexts of the transferable plasmid-mediated blaCTX-M-55 gene in Enterobacteriaceae were detected and characterized in this study.MethodsIsolates were obtained from the First Affiliated Hospital of Zhengzhou University between September 2015 and March 2016. Based on polymerase chain reaction and BLAST analysis, resistance genes and genetic context of the blaCTX-M-55 gene were investigated. Conjugation experiments and multilocus sequence typing were performed to demonstrate plasmid-mediated blaCTX-M-55 transmission.ResultsThirteen blaCTX-M-55-positive isolates of Enterobacteriaceae were obtained. Seven isolates were Escherichia coli, 3 were Klebsiella pneumoniae, 1 was Citrobacter freundii, 1 was Morganella morganii and 1 was Serratia marcescens. The blaCTX-M-55 gene has not previously been identified from C. freundii and M. morganii. Four different blaCTX-M-55 genetic contexts were identified, and all of them harbored ISEcp1 in the region upstream of blaCTX-M-55 (in two cases, ISEcp1 was truncated by IS26, and in one case, it was truncated by IS1294), whereas ORF477 was detected downstream of the blaCTX-M-55 gene from 12 of 13 strains. The novel genetic context of ISEcp1∆-blaCTX-M-55-∆IS903 was firstly detected the IS903 element which was identified downstream of blaCTX-M-55. A conjugation assay revealed that all blaCTX-M-55 plasmids were quickly and easily transferable to recipient E. coli, which then presented resistance to multiple antibiotics.ConclusionsNumerous blaCTX-M-55-positive strains were isolated in a short period of 7 months. The findings indicate that blaCTX-M-55 was rapidly disseminated. The genetic context and conjugative transfer found in this study demonstrate that there is active transmission of blaCTX-M-55 among strains of Enterobacteriaceae in China, which could give rise to an urgent global public health threat.

<p>Characterization of NDM-5- and CTX-M-55-coproducing <em>Escherichia coli</em> GSH8M-2 isolated from the effluent of a wastewater treatment plant in Tokyo Bay</p>

“…In addition to NDM-5, GSH8M-2 harbors CTX-M-55, which was first reported in 2006 in Thailand25 and is a variant of CTX-M-15 in the CTX-M-1 cluster, with only one amino acid substitution (Ala 80 Val). Over the past decade, CTX-M-55-producing E. coli isolated from animals and in clinical settings has been increasing 26. Moreover, the bla CTX-M-55 -positive plasmid pGSH8M-2-3 is associated with other ARGs ( aph(3ʹ)-Ia, floR, fosA3 , and qnrS2 ), the co-localization of the florfenicol resistance gene floR is of marked concern because floR is detected in increasing amounts in both veterinary27 and clinical isolates28 within China.…”

Enterohaemorrhagic Escherichia coli O121:H19 acquired an extended-spectrum β-lactamase gene during the development of an outbreak in two nurseries

“…CTX-M-55 is a variant of CTX-M-15 and has a single amino acid substitution at position 80 [36]. CTX-M-55 was first detected in Thailand, and since then Enterobacteriaceae isolates carrying bla CTX-M-55 have mainly been reported in Asian countries [36–38]. In Japan, EHEC strains harbouring ESBL have rarely been reported.…”

Risk Factors for Extended-Spectrum-β-Lactamase-Producing Escherichia coli in Community-Onset Bloodstream Infection: Impact on Long-Term Care Hospitals in Korea

“…CTX-M-15 was the most common type among ESBL-EC from clinical blood isolates at Korean hospitals [ 27 , 28 ]. CTX-M-55 can be rapidly disseminated and transmitted in clinical practices in China [ 29 ] and is the most frequently detected ESBL-EC type of animal-origin in Korea [ 30 , 31 ]. This reflects temporal trends in bla CTX-M ing that bla CTX-M-15 and bla CTX-M-14 have displaced other genotypes in many parts of the world [ 32 ].…”