Virulence genotyping and drug resistance of diarrheagenic Escherichia coli in Suzhou, Jiangsu Province from 2019 to 2023

ObjectiveTo investigate the genotyping and drug resistance trends of 461 strains of diarrheagenic Escherichia coli (DEC) isolated and identified in Suzhou, Jiangsu Province from 2019 to 2023.MethodsDEC detected in Suzhou in the past 5 years was used as the research subject, and the virulence genotyping was tested by real-time fluorescence quantitative polymerase chain reaction (PCR). The microbroth dilution method was used to perform drug susceptibility test, and the corresponding susceptibility (S), intermediate (I) and resistance (R) results were obtained based on the minimum inhibitory concentration (MIC) values, according to the criteria of United States Clinical and Laboratory Standardization Committee (CLSI) 2017. Differences of DEC drug resistance among different virulence genotypes were compared by χ2 test or Fisher exact probability method.ResultsA total of 461 DEC strains were detected in Suzhou from 2019 to 2023, of which the highest proportion was enterotoxigenic Escherichia coli (ETEC) accounting for 45.77% (211/461), followed by enteropathogenic Escherichia coli (EPEC) accounting for 32.32% (149/461) and enteroaggregative Escherichia coli (EAEC) accounting for 20.39% (94/461), while enterohemor-rhagic Escherichia coli (EHEC) and enteroinvasive Escherichia coli (EIEC) were individually distributed. The antimicrobial drug with the highest resistance rate was ampicillin (61.61%), followed by cefazolin (49.89%) and nalidixic acid (44.47%). There were statistically significant differences in drug resistence rates of the three major virulence genotypes of DEC (ETEC, EPEC and EAEC) to ampicillin (AMP), ampicillin/sulbactam (AMS), amoxicillin/clavulanic acid (AMC), cefoxetine (CFX), gentamicin (GEN), streptomycin (STR), tetracycline (TET), nalidixic acid (NAL), and chloramphenicol (CHL), and methotrexate/sulfamethoxazole (SXT). The multi-drug resistance (MDR) rate of DEC was 59.87% (276/461), and the MDR rate of each genotype, from high to low, was EIEC (75.00%), EAEC (71.28%), EHEC (66.66%), EPEC (61.74%) and ETEC (52.86%).ConclusionETEC, EPEC and EAEC are the main genotypes prevalent in DEC in Suzhou in recent years. The drug resistance strains and MDR are still serious, which should arouse wide public health concern and take targeted prevention and control measures.