Resistance And Virulence Genes Of Escherichia Coli Isolated From Clinic

Object①To understand the characteristics of the distribution and drug resistance of Escherichia coli(E.coli) isolated from clinic in Qingdao Municipal Hospital.②To research the antimicrobial resistance of the ESBLs-producing E.coli and the Non ESBLs-producing E.coli.③To analyse the expression of virulence genes in the ESBLs-producing E.coli and the Non ESBLs-producing E.coli.Methods④From Oct2010to Aug2011,96E.coli strains (46ESBLs positive E.coli and50ESBLs negative E.coli) from Microbiology Laboratory were collected in Qingdao Municipal Hospital.②According to the National Committee for Clinical Laboratory Standards (NCCLS) which recommended K-B disk diffusion method determinated the antimicrobial resistance of the the ESBLs-producing E.coli and the Non ESBLs-producing E.coli.③Virulence gene (VT1、CNF2、CNF2、elt、est、hlyA、eaeA、 bfpA) were tested by polymerase chain reaction(PCR). The expression difference of genes between ESBLs positive E.coli and ESBLs negative E.coli by the statistical method was analyzed.Results①96E.coli isolates was mainly from ICU(12/96,12.5%)、nephrology department (12/96,12.5%) and outpatient clinic (12/96,12.5%),the detecting rate of E.coli was more higher in urine、 sputum samples(49/96,51.0%^、30/96,31.3%).②Among common clinical antibacterials, the sensitivity of imipenem was the highest(95/96,99.0%), followed by piperacillin/tazobactam(88/96,91.6%), cefoperazone/sulbactam (87/96,90.6%); the drug resistance of ampicillin was the highest(85/96,88.5%), followed by trimethoprim-sulfamethoxazole(66/96,68.8%), cefazolin(63/96,65.6%) in the E.coli isolates.③The resistance rates of the ESBLs-producing E.coli isolates to ampicillin, cefazolin, ceftazidime, cefepime, aztreonam, levofloxacin, trimethoprim-sulfamethoxazole, gentamicin, ampicillin/sulbactam were100%,100%, more than90%, more than90%,89.1%,87.0%,76.1%,73.9%,56.5%respectively. Low resistance rate of the ESBLs-producing E.coli isolates was observed to cefoperazone/sulbactam(4.3%), and imipenem and piperacillin/tazobactam resistance was not found in ESBLs-producing E.coli isolates; the resistance rates of the Non ESBLs-producing E.coli isolates to ampicillin, levofloxacin, trimethoprim-sulfamethoxazole, gentamicin, cefazolin, ampicillin/sulbactam were78%,64%,62%,44%,34%,32%respectively. Low resistance rate of the Non ESBLs-producing E.coli isolates were observed to aztreonam(16%), cefepime(16%), ceftazidime(12%), piperacillin/tazobactam(4%), and imipenem resistance was not found in Non ESBLs-producing E.coli isolates.④The rate of multiple drug-resistant strain was91.3%, the detection rate of CNF2, hlyA, eaeA, VT1, est, bfpA, elt, and CNF1in46ESBLs-producing E.coli isolates was6.5%,69.6%,69.6%,89.1%,10.9%,26.1%,8.7%, and19.6%, respectively. In the Non ESBLs-producing E.coli strains the rate of multiple drug-resistant strain was62.0%, the positive rate of CNF2, hlyA, eaeA, VT1, est, bfpA, elt, and CNF1was16.0%,28.0%,64.0%,38.0%,6.0%,34.0%,10.0%, and24.0%, respectively. The statistical analysis showed that the difference on the positive rate of multiple drug-resistant strain between the ESBLs-producing E.coli isolates and the Non ESBLs-producing E.coli strains was statistically significant (χ2=11.293, P<0.05), and the difference on the detection rate of hlyA and VT1between the ESBLs-producing E.coli isolates and the Non ESBLs-producing E.coli strains was also statistically significant (χ2=16.585, χ2=26.724,P<0.05).Conclusion①The doctor should use imipenem preferred by experience, followed by piperacillin/tazobactam, cefoperazone/sulbactam. Then to adjust the drug according to antimicrobial susceptibility combined with condition.②The drug resistance phenomenon of ESBLs-producing E.coli strains was more serious than Non ESBLs-producing E.coli strains. It is related that the positive rate of multiple drug-resistant strains in the ESBLs-producing strains is more than in the Non ESBLs-producing strains and the expression rate on some virulence genes of ESBLs-producing E.coli strains are higher than Non ESBLs-producing E.coli strains.