Investigation of the susceptibility of extended spectrum beta-lactamase producing escherichia coli and klebsiella spp. to carbapenems and beta-lactamase inhibitor combinations

2. ABSTRACTInvestigation of the Susceptibility of Extended Spectrum Beta-Lactamase Producing Escherichia Coli and klebsiella Spp. to Carbapenemsand Beta-Lactamase Inhibitor CombinationsExtended Spectrum Beta Lactamases (ESBL) which are the mostsignificant cephalosporin resistance among Klebsiella and Escherichia coli hasbeen continuously increasing since from the first detection at early 1980?s.The common concern abaout the ESBLs is the rapid spreading of the resistancein a wide geographic locations including our country . due to the fact that thereis a limited number of alternative agents which are effective for ESBL strains,the therapy of the infection caused by ESBL strains is become a considerablehealth problem. Besides Beta-Lactamase inhibitor combinations are suggestedas to be usable in the due to ESBL producing bacterias infections, whetherthey are found effective in in vitro tests.In this study, it was aimed to determined in vitro activity of imipenem,meropenem, cefoperazone-sulbactam, piperacillin-tazobactam ve amoxicillin-clavulanic acid against to ESBL producing Klebsiella and E.Coli strains. Atotal of 300 strain, of which 230 E.Coli, 43 K. pneumoniae and 27 K. oxytocawere included in to the study. These strains were isolated from the impatientswho had been visited Fırat Medical Center?s policlinics and who had beenestablished nasocomial infection diagnosis according to CDC (Centers forDiseases Control and Prevention) criteria between January 2003 and May2005. ESBL production of the strains were determined by using Double-DiskSynergy (DDST) Test . The susceptibility of the strains against to the studiedantibiotics were investigated with broth mirodulition metho to therecommendations of NCCLS (National Committee for Clinical LaboratoryStandards).Any resistance to imipinem and meropenem among ESBL producingbacterias of which are E.Coli and Klebsiella Spp. was not detected.Susceptibilities of E.Coli strains to piperacilin- tazobactam, cephoperazon-sulbactam and amoxicillin-clavulanic acid were found as 75.2%, 72.6% and29.3% , respectively. Piperacilin- tazobactam and cephoperazon-sulbactamwere determined as equally active as 69.8% to K. pneumaniae strains.3Susceptibilities of K.oxytoca strains to piperacillin-tazobactam andcephoperazon-sulbactam were found as 55.8% and 40.7%, orderly. Thesusceptibility of amoxicillin-calvulonic acid among K. pneumaniae and K.oxytoca strains was detected as 23.3% and 18%, respectively. Thus E.colistrain were observed as more susceptible to beta-lactamase inhibitorcombinations than tose of Klebsiella strains. Eleven E.coli , three K.pneumoniae and one K.oxytoca were found resistant to all three agents.MIC50/90 values of imipenem among E.coli an Klebsiella spp. wasdetermined as 0.5/0.5 mcg/ml, MIC50/90 values of meropenem of thesepathogens were 0.12/0.12 mcg/ml. MIC50/90 values of piperacillin-tazobactamand cephoperazon-sulbactam of E.coli were found 8/4-64/4 ve 8/8-64/64mcg/ml, of Klebsiella spp. 16/4-128/4 ve 16/16-128/128 mcg/ml, respectively.MIC50 values of piperacillin-tazobactam and cephoperazon-sulbactam for bothbacterial strain were observed in susceptibility breakpoints, whereas MIC90values of the both antibiotics in Klebsiella strains were determined inresistance limits. However, in E.coli strains, MIC90 values of piperacillin-tazobactam were found in intermediate susceptibility but, MIC90 values ofcephoperazon-sulbactam were found in resistance limits. MIC50/90 values ofamoxilin-clavulanic acid for E.coli strains wetre found 16/8-64/32 mcg/ml; forKlebsiella spp. were found 32/16-128/64 mcg/ml, orderly. Therefore, neitherMIC50 nor MIC90 values of amoxilin-clavulanic acid were found insusceptibility breakpoints for both group of organism.As a result, piperacillin-tazobactam was found relatively more activeagainst to ESBL producing E.coli and K.oxytoca strains, than thecephoperazon-sulbactam. Both antibiotics were found equally sensitive in K.pneumoniae strains. We have commenced that these antibiotics could be moreuseful for empirically managements in non-complicated or non-life threateninginfections. They might be used in life-threatening infections as long as thefollowing susceptibility tests. Owing to thje determined activity of amoxilin-clavulanic acid, it seems to be far away from the safely utilization in ESBLinfections. Still imipenem and meropenem is remaining the most activeantibiotics in the case of ESBL infections.Key-Words: ESBL, imipenem,meropenem, cephoperazon-sulbactam,piperacillin-tazobactam, amoxilin-clavulanic acid4