Abstract:Abstract: [Objective] To investigate co-existence of resistance genes (β-lactamases, BLs, and aminoglycoside-modifying enzymes, AMEs) and their association with the genetic marker genes of ClassⅠ, Ⅱ, Ⅲ integrons carried by multiresistant Escherichia coli isolates. [Methods] We used VITEK-GNS to determine the susceptibility of 136 isolates to 14 antibiotics, disc agar diffusion test to confirm ESBL-producing isolates, PCR to analyze BLs, AMEs and integrons genes, conjugation and plasmids extraction to locate the methylase genes. [Results] We found that 70.59% of the isolates produced ESBLs. They showed stronger resistance against 9 antibiotics than isolates without ESBLs in 14 antibiotics. PCR amplification showed that the positive rate of BLs, AMEs and qacE△1-sul1 was 96.32%, 100% and 94.12%, respectively, but ClassⅡ, Ⅲ integrons genes were negative. Only one strain was oprD2 gene negative. 90.44% of the isolates were both positive for BLs and qacE△1-sul1 genes, and 94.12% for AMEs and qacE△1-sul1 genes, but there was no statistical significance. 90.44% of the isolates were all positive for the 3 genes. 12 strains carried 16S rRNA methylase genes including armA (2.21%), rmtB (7.35%) while rmtA, rmtC, rmtD were negative. The conjugation assay and plasmids mapping results showed that the methylase genes were located on the 23 kb plasmid, and the efficiency of transformation was 83.3%. [Conclusions] The results suggested that there was a tight correlation between the 3 genes (BLs, AMEs and qacE△1-sul1)and the incidences of multi-resistance of Escherichia coli, but there was no correlation of the incidence of multi-resistance with ClassⅡ, Ⅲ integrons. 16S rRNA methylase genes harboured plasmids of ~23 kb which transformed other isolates within the same strains efficiently.
