Abstract:Objective To investigate antimicrobial resistance, gene homology and main genotypes of clinically isolated diarrheagenic Escherichia coli (DEC) in Anhui Province. Methods Antimicrobial susceptibility testing was performed with microbroth dilution method, genotyping detection and homology analysis was conducted with multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Results Among 268 strains of DEC, 57.1% were multidrug-resistant organisms, including 118 strains of enteroaggregative Escherichia coli (EAEC), 98 strains of enterotoxigenic Escherichia coli (ETEC) and 47 strains of enteropathogenic Escherichia coli (EPEC), resistance rates of 3 types of pathological strains to commonly used antimicrobial agents were as follows: ampicillin 83.9%, 73.5%, 78.7%, nalidixic acid 65.3%, 75.5%, 34.0%, cefazolin 53.4%, 35.7%, 34.0%, tetracycline 61.0%, 31.6%, 74.5%, compound sulfamethoxazole 63.6%, 23.5%, 46.8%, ampicillin/sulbactam 28.0%, 9.2%, 29.8%, gentamicin 34.7%, 7.1%, 34.0%, chloramphenicol 22.9%, 5.1%, 21.3%, ciprofloxacin 18.6%, 4.1%, 14.9%; two EAEC strains and 1 ETEC strain were resistant to imipenem. 55 EAEC strains were divided into 35 ST, the dominant genotype was ST10 (14.5%); 55 ETEC strains were divided into 14 ST, the dominant genotypes were ST48 (32.7%) and ST218 (16.4%); 15 EPEC strains were divided into 12 ST, the do-minating genotypes were ST28 (13.3%), ST517 (13.3%) and ST2088 (13.3%). Minimum-evolution (ME) tree analysis showed that among 55 ETEC strains, 5, 3, 2 and 2 strains isolated from Ma'anshan City were 100% homologous respectively, 5 strains isolated from Hefei City were 100% homologous; among 55 EAEC strains, 2 strains isolated from Fuyang City and 2 strains isolated from Chuzhou City were 100% homologous respectively; among 15 EPEC strains isolated from Ma'anshan City, 2 strains in 2 groups were 100% homologous. PFGE homo-logy cluster analysis results of 50 EAEC strains were as follows: 2 strains isolated from Bengbu City were 100% homologous, homology of the other strains was less than 90%; gene homology of 21 EPEC strains were all less than 75%; homology of 30 ETEC strains, 3 enteroinvasive Escherichia coli (EIEC) strains, and 5 ETEC+aEAEC strains reached 97.6% with 2 strains and 93.6% with 2 strains respectively, and the homology of the remaining strains was below 90%. Conclusion Antimicrobial resistance of clinically isolated DEC in Anhui Province is se-rious, resistance rate of EAEC is higher than that of EPEC and ETEC, resistance rate of ETEC is the lowest among the pathogenic types. Molecular typing detection found that the genotypes of clinically isolated DEC in this area are relatively scattered, among the pathogenic types, genotype of ETEC is relatively concentrated. ME tree analysis suggests that ETEC may have a regional homologous infection. In molecular typing technology, MLST can distinguish dominant genotype and aggregation, which is better than PFGE typing.