Epidemiological And Resistant Study On Bacteria Producing Extended-Spectrum β-lactamases

Soon after introducing the clinical use of extended-spectrum cephalosporins, such as cefetaxime, ceftriaxone, aztreonam and ceftazidime, extended-spectrum -lactamases (ESBLs) were firstly isolated from Enterobacleriaceae in Europe. Then, reports on ESBLs spread around the world. ESBLs were produced by Gram-negative bacteria, such as Klebsiella pneumoniae, Escherichia coli, Proteus mirabilis, Serratia marcescens, Enterohacter cloacae. Acinetobacter sp. and Pseudomonas aeruginosa, and could inactivate oxyimino- -lactams like third-generation cephalosporins and aztreonam, due to their wider substrates for hydrolysis than penicillinase like TEM-1, TEM-2 and SHV-1, were designated. The resistance of ESBLs-producing Enterobacteriaceae has currently become one of the most important nosocomial resistance problems around the world, and their detecting is harder in the laboratory, and due to diverse genotypes, exist distinction of resistance and detecting substrates between them. Therefore, we had a study of the best detective substrates and drug-resistance of ESBLs-producing K. pneumoniae and E. coli isolates in the First Affiliated Hospital Anhui Medical University so that we could prevent regional prevalence of ESBLs producers and guide clinical therapy in order to avoid delaying therapy and wasting drugs.we studied ESBLs epidemiology, detecting, resistance and resistant genotypes of 201 K. pneumoniae and E. coli strains isolated from the First Affiliated Hospital Anhui Medical University, Anhui Province China between 1999 and 2001.To study risk factors for infections caused by K. pneumoniae and E. coli producing extended-spectrum - lactamases and drug-resistance. To study the best detective substrate of ESBLs. To investigate the epidemiological data and drug-resistance ofESBLs producers .To study resistant genotypes of ESBLs producers isolated from our hospital between 1999 and 2001.Results and Conclusions The risks of ESBLs-producing bacteria infections was significantly higher in the exposure to invasive manipulations, P -lactams drugs, the third generation cephalosporins and nosocomial infections caused than the nonexposure.Cefetaxime was the best detective substrates of ESBLs-producing K. pnewnoniae and E. coli isolates, and then ceftriaxone and aztreonam in our hospital. Relying on ceftazidime resistance as a single marker for presence of ESBLs may be unreliable.The incidences of ESBLs in K. pneumoniae and E.coli were 50 percent and 27.2 percent respectively. The average incidence was 34.6 percent. Compared with the resistance rates of non-ESBLs producing strains, those of ESBLs producers to ceftazidime, aztreonam, cefepime, cefoxitin, piperacillin/tazobactam, cefoperazone/ sulbactam, amikacin and ciprofloxacin increased. But all ESBLs producers were susceptible to imipenem. Therefore carbapenems like imipenemwere most reliable therapeuticdrugs.Of 64 ESBLs-producers, the main type of -lactamases was TEM-type, and then SHV-type and CTX-M-type. However, concrete molecular epidemiology will still wait for more research.