The Study Of Drug Resistance Of The Common Enterobacteriaceae Isolates

Objective: To investigate the drug-resistance of common Enterobacteriaceae isolates and analyze the isolates producing extended-spectrumβ-lactamases and AmpCβ-lactamases, so that guide the reasonable clinical use of antimicrobial agents.Methods: From June 2005 to June 2006, we have collected the 356 strains of Enterobacteriaceae bacterium and identified by API20E system. The drug susceptibility test was performed by Disk diffusion method. Extended-spectrumβ-lactamases were detected by double disk synergy tests and disk confirmatory tests recommended by Clinical and Laboratory Standards Institute(CLSI) 2006 year. AmpCβ–lactamases were detected by preliminary screening test, double disk synergy test and three-dimensional test according to CLSI 2006. The all dates were analyzed by WHONET 5.3 software and compared the drug- resistance of the strains of Escherichia coli and Klebsiella penumoniae ESBLs producing to ESBLs non-producing.Results :1. The respiratory infection is common in clinical infectious diseases, the most strains was isolated from sputum, second was pus and body fluid and the next was urine, the rates of isolation was 47.3%,29.8% and 13.6 %,respectively.2. 356 strains Enterobacteriaceae were frequently detected in our clinical hospital is Escherichia coli , Klebsiella penumoniae , Enterobacter cloacae, Serratia and proteus one by one . Most of Enterobacteriaceae isolates were susceptible to both imipenem and meropenem,. among these the highest rates of sensitiveness of Escherichia coli to antibiotic is imipenem and meropenem, 94.3% and 98.4% respectively. Next is amikacin, piperacillin/ tazobactam , cefepime, and cefoperazone/sulbactam, 83.2%, 78.2%,66.9%,and 60.7%,respectively. The susceptibility of ampicillin, piperacillin, cefuroxime, cefotaxime,cefoperazone,ciprofloxacin and gentamycin are all below 35%. The result of Klebsiella pneumoniae is similar to Escherichia coli, the difference is that the susceptibility of it(52.6%) is higher than Escherichia col(i20.3%), the activities of cefepime and cefotaxim (84.9% and 52.2%, respectively )to Klebsiella pneumoniae is higher than Escherichia coli ( 66.9%and 32%, respectively ). The resistance of Enterobacter cloacae are higher than many antibiotic . for Enterobacter cloacae , the activity of imipenem is best in vitro.2. The incidences of Klebsiella pneumoniae and Escherichia coli producing ESBLs isolates were 51.9% and 25.9% respectively .3.The highly isolates rates of extended spectrum　β-lactamases bring many difficulties to clinical treatment , Klebsiella pneumoniae and Escherichia coli producing ESBLs except to susceptible to imipenem, the rates of resistance is 3%and 3.4%, respectively .The resistance rates of ESBLs-producing strains of Escherichia coli to cefoperazone/sulbactam, piperacillin/ tazobactam ,ceftazidime, cefepime , amikacin and cefoxitin is 10.4%,4.6%,13.4%,11.3%,9.3%and 20.9%, respectively [11-14].. The resistance rates of ESBLs- producing strains of Klebsiella pneumoniae to them is 17.9%,8.4%,20.7%,15.4%, 10.2% and 26.2%,. respectively , compared to enzyme–producing stains, the rates of resistance is not change significantly .4. The resistance rates of ESBLs-producing strains of Escherichia coli to piperacillin ,cefazolin, cefurxime, cefotaxim is 93.8%, 95.5%, 95.4%, 77.6%,respectively .The resistance rates of ESBLs-producing strains of Escherichia coli to these anti-microbial is 93.8%,95.5%,95.4%,77.6%,respectively . which is higher than the former significantly. The result of Klebsiella pneumoniae is similar to Escherichia coli, the resistance rates of ESBLs-producing of Klebsiella pneumoniae to piperacillin ,cefazolin, cefurxime, cefotaxim is 89.7%,96.4%,88.9%,61.5%,respectively .The resistance rates of non-ESBLs-producing of Klebsiella pneumoniae to these anti-microbial is 43.9%, 35.9%,30.9%,13.8%,respectively .which is higher than the former significantly.5. There are 3 producing AmpCβ-lactamase strains c?ome from Klebsiella penumoniae, only 1 strain Escherichia coli producing AmpCβ-lactamase. 9 producing AmpCβ-lactamase strains of Enterobacter cloacae is detected. Conclusion: Escherichia coli and Klebsiella penumoniae is the most common pathogenic in clinical infection . Most of enterobacteriaceae isolates were susceptible to imipenem and meropenem, the rates of Escherichia coli and Klebsiella penumoniae producing ESBLs is higher. The drug–resistance increased of the strains producingβ-lactamases than not producingβ-lactamases, and the mechanism of the drug–resistance multiplicity .More attention should be paid to their detection and surveillance; their resistance to anti-microbial agents should be known by clinicians. In our hospital ,the main mechanism of resistance of third-generation cephalosporins are still producing ESBLs, it is necessary to monitor the bacterial resistance to antibiotics and choose antibiotics based on the results of susceptibility tests. So that prevent the popularity of drug-resistance.