Drug resistance analysis and genetic evolution characteristics of chicken-derived tet(X4)gene-positive Escherichia coli in Handan area,Hebei Province
In order to explore the drug resistance and genetic evolution characteristics of chicken-derived tet(X4)gene-positive E.coli in Handan area,Hebei Province,in the test,a total of 400 chicken fecal samples from three large-scale commercial poultry farms in this area were collected from March to June 2020 and May 2021,which were scribed and inoculated on MacConkey agar medium containing 4 mg/L tigecycline to isolate tigecycline-resistant suspected E.coli strains.The isolated strains were further identified by Gram staining,biochemical test and PCR amplification and sequencing of 16S rDNA gene.Subsequently,tet(X4)gene detection was performed on tigecycline-resistant E.coli strains.Then,other drug resistance gene detection,drug resistance analysis,serotype identification,phylogenetic group analysis,plasmid replicon typing,and multilocus sequence typing(MLST)analysis were performed on the tet(X4)gene-positive strains.The results showed that a total of 96 strains of tigecycline-resistant E.coli were isolated.Among them,13 strains were positive for tet(X4)gene,and the detection rate was 13.5%.In the tet(X4)gene-positive strains,the detection rate of parC gene was 100%.Then,from high to low,blaTEM-1,blaOXA-48,tet(C),tet(M),mph(A)and qnrA genes were detected in order,with the detection rates of 84.6%,61.5%,38.5%,23.0%,23.0%and 7.7%,respectively.The resistance rates of 13 tet(X4)-positive strains to sulfamethoxazole/trimethoprim,cefotaxime,ampicillin,tetracycline,doxycycline,tigecycline were 100%.The resistance rates to cefepime,gentamicin,polymyxin,aztreonam,fosfomycin and amikacin were 84.6%,76.9%,69.2%,69.2%,61.5%and 15.4%,respectively.All of them were resistant to 9 or more antibiotics,of which 9 strains were resistant to 10 or more antibiotics.Thirteen tet(X4)gene-positive strains belonged to three O-antigen serotypes.Among them,there were 11 strains of O119 serotype,accounting for 84.6%,with 1 strain of O112 serotype and O39 serotype each.The 13 strains positive for tet(X4)gene belonged to two phylogenetic groups,of which 9 strains were in group A/C,accounting for 69.2%,which was the dominant group.There were 4 strains in group B1,accounting for 30.8%.A total of 13 tet(X4)positive strains carried 6 plasmids(P0111,IncF,IncI1,IncFIB,IncHI2,IncX2),among which most strains belonging to the plasmid replicon spectrum IncI1+IncF+P0111 accounted for 76.9%.The 13 tet(X4)positive strains were divided into 4 sequence types(ST);among them,there were 10 strains of ST3817,accounting for 76.9%,which were the dominant ST;ST641,ST602 and unknown ST type each had 1 strain.These results indicated that multi-drug resistance of E.coli positive for tet(X4)gene was widespread in Handan area,Hebei Province;the dominant serotype was O119;the dominant phylogenetic group was group A/C;and the dominant ST was ST3817.
E.colidrug resistancetet(X4)genegenetic evolution characteristicsHandan area
万方数据
维普
