健康老年人肠道定植产ESBLs大肠埃希菌中插入序列共同区（ISCR）研究

Objective: To investigate the prevalence of ISCR and the genotype of ESBL among the ESBL-producing Escherichia coli isolated from healthy elderly. Methods: From January to March in 2015, a total of 262 Escherichia coli were isolated. The production of extended-spectrum β-lactamases(ESBLs) was initially screened by phenotypic experiments.PCR was used to detect the gene of ISCR1, ISCR2, ISCR3, ISCR4, ISCR5, CTX-M-1,CTX-M-9,SHV,TEM, CTX-M-2.Antimicrobial susceptibility test was performed by Agar dilution method according to the most recent guidelines of the Clinical and Laboratory Standards Institute. These strains were divided into ISCR-positive and ISCR-negative groups. We compared the antibiotic resistance rate of the two groups. Result: For the 262 strains, the antimicrobial resistance rate was as follows: Amikacin(0.76%),Cefotaxime(99.6%),Fosfomycin(3.4%),Cefepime(12.98%),Ceftazidime(22.9%),Cefoxitin(9.9%),Levofloxacin(46.6%),Ampicillin(100%),Ampicillin-Sulbactam(57.6%),Piperacillin-Tazobactam(0%),Meropenem(0%) and Ertapenem(0%). The positive rate of the genes were ISCR1 (22.9%), ISCR2 (10.3%), ISCR3 (5.3%), ISCR4 (5.3%), ISCR5 (1.9%), CTX-M-1 (34.3%), CTX-M-9 (69.5%), SHV (0.38%), TEM (41.98%), CTX-M-2 (2.3%). The group containing ISCR had higher resistance rate in most antibiotics, except for Amikacin and others with the resistance rate of zero. Conclusion: ISCR may be associated with higher antibiotic resistance in ESBLs producing Escherichia coli.