In:
Frontiers in Cellular and Infection Microbiology, Frontiers Media SA, Vol. 12 ( 2022-8-8)
Abstract:
The aim of this study was to clarify the molecular characterization of NDM-1-producing carbapenem-resistant Enterobacter cloacae complex (CREL) at a teaching hospital in Chongqing, China. Methods Antimicrobial susceptibility and resistance genes were analyzed. Epidemiological relationship was analyzed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Conjugation experiments were performed to determine the transferability of plasmids. Whole-genome sequencing (WGS) of strains was implemented, and the genetic environment of the bla NDM-1 - and mcr-9 -carrying plasmids was analyzed. Results A total of 10 bla NDM-1 -positive CREL isolates were identified. All isolates harbored multiple resistance genes. ECL68 and ECL78 co-produce bla NDM-1 and mcr-9 . Among the four different sequence types (STs) detected, ST1466 was assigned as a novel ST. Six isolates exhibited highly similar PFGE patterns. Conjugation assay proved that all plasmids containing bla NDM-1 or mcr-9 could be transferred to the recipient Escherichia coli . WGS indicated that bla NDM-1 genes were carried by diverse plasmids, including IncHI2/IncN, IncX3, and one unclassified plasmid type. The backbone structure of these plasmids is involved in replication initiation ( repAB ), partitioning ( parABM ), and conjugation/type IV secretion ( tra/virB ). Analysis of the genetic environment showed that bla NDM-1 in three plasmids exhibited a highly similar structure to protype Tn 125 . Co-existence of bla NDM-1 and the colistin resistance gene mcr-9 was detected in the two isolates, ECL68 and ECL78. In ECL68, bla NDM-1 and mcr-9 were present on the same plasmid while located in two separate plasmids in ECL78. The genetic environment of mcr-9 was organized as IS 26-wbuC-mcr-9- IS 903-pcoS-pcoE-rcnA-rcnR , and the two-component system encoding genes qseC and qseB was not found in two plasmids, which could explain mcr-9 -harboring strains’ colistin susceptibility. Conclusions We first report a nosocomial outbreak of NDM-1-producing E. cloacae complex ST177 in China. Conjugative plasmids contributed to the horizontal transfer of antibiotic resistance genes. The prevalence and even coexistence of bla NDM-1 and mcr-9 may further threaten public health. Our results highlight further surveillance for bla NDM-1 , and mcr-9 is essential to prevent its dissemination.
Type of Medium:
Online Resource
ISSN:
2235-2988
DOI:
10.3389/fcimb.2022.935165
Language:
Unknown
Publisher:
Frontiers Media SA
Publication Date:
2022
detail.hit.zdb_id:
2619676-1
