Studies on Antimicrobial Resistance of Extended Spectrum Beta- lactamases-producing Strains in Escherichia coli

Objective To investigate the isolated rate of extended spectrum beta-lactamases carried in Escherichia coli in People’s Hospital of Yunxi County, and to analyze their drug resistance to 14 kinds of antibacterial agents. Methods A total of 181 strains of Escherichia coli were isolated from People’s Hospital of Yunxi County. The minimum inhibitory concentration (MIC) of 14 antibacterial agents against the clinical isolates was detected by double agar dilution method. Results Sixty ESBLs-producing strains were detected in the 181 strains of Escherichia coli, and the detection rate was 33.1%. The drug resistance rates of 153 E. coli strains of ESBLs producers to second generation cephlosporins were exceeded 90%; to other cephlosporins, the drug resistance rates were between 12.5% and 55%. For gentamicin, ciprofloxacin, and tetracycline,the drug resistance rates were between 70% and 90%. MIC50 for ceftizodime and amikacin was in susceptibility. For aztreonam, MIC50 has reached to intermediate. MIC50 and MIC90 for the other antibacterial agents were in resistance. However, all of these ESBLs producers were susceptible to imipenem. The difference for ESBLs-producing E. coli compared with non ESBLs-producing E. coli in amikacin and tetracycline were significant, while the resistance to piperacillin / tazobactam was insignificant; but to other antibacterial agents the resistance was highly significant. Conclusions The rate of ESBLs-producing in E. coli was 32.7%. Extended spectrum beta-lactamase producers show more prominent drug resistances to most of the antibacterial agents, while all of these detected strains remain susceptible to imipenem.