Molecular type and antimicrobial resistance analysis of diarrheagenic Escherichia coli in Wuhan from 2019 to 2021

ObjectiveThis study aimed to investigate the distribution of virulence genes， antibiotic resistance， and molecular types of diarrheagenic Escherichia coli （DEC） in Wuhan， Hubei Province， China.MethodsDEC strains identified through biochemical means and a time-of-flight mass spectrometer were routinely collected from five medical institutions. Multiple polymerase chain reactions and drug sensitivity tests were carried out. The molecular characteristics of DEC strains were determined using pulsed field gel electrophoresis （PFGE） and multi-locus sequence typing. Homology analysis was carried out based on clustering analogy and the minimum spanning tree.ResultsA total of 59 DEC strains were collected， including 29 strains of enterotoxigenic Escherichia coli （ETEC， 49.15%）， 15 strains of enteroaggregative Escherichia coli （EAEC， 25.42%）， and 15 strains of enteropathogenic Escherichia coli （EPEC， 25.42%）. The resistance rates of DECs to the 11 antibiotics （except polymyxin E） varied， and were especially high for the following： ampicillin （67.80%）， nalidixic acid （61.02%）， tetracycline （45.76%）， cotrimoxazole （37.29%）， cefotaxime （30.51%）， and chloramphenicol （13.56%）. As determined by PFGE， both EAEC and EPEC had 14 different bands， belonging to 11 different sequence types （STs）； whereas ETEC had 28 different bands belonging to 10 different STs. In addition， more than 50% of STs from ETEC were classified as clonal complexes （CC）-10.ConclusionThe contamination of DECs persists in Wuhan， and antimicrobial resistance is at a critical level. The genotypes from EAEC and EPEC are relatively scattered based on molecular detection and typing of DECs. CC-10， the dominant clone complex of ETEC， is widely distributed in Wuhan.