Cefepime-Clavulanate ESBL E-test for Detection of Extended Spectrum Beta-Lactamases in AmpC Co-producing klebsiella species

Abstract

The emergence and spread of antimicrobial resistance continue to challenge our abilities to treat serious infections in both the nosocomial and the community settings. While new antimicrobial agents were designed to treat multiresistant pathogens that have been introduced in the past few years, resistance has continued to emerge and spread. Beta-lactamases are the most important mechanism of drug resistance among gram-negative bacteria Extended spectrum -lactamases (ESBLs) represent a major group of β-lactamases which are found in a significant percentage of Escherichia coli and K. pneumoniae strains. The prevalence of extended-spectrum β-lactamase (ESBLs) production in strains of the Enterobacteriaceae family, such as Escherichia coli, Klebsiella spp. and Enterobacter spp., has been increasing continuously during the past decade in Europe and worldwide Currently, the appropriate methods for ESBLs detection are seriously concerned because of the failure in treatment of the 3rd generation cephalosporins and aztreonam. The method for detection is complicated due to the varieties of enzymes. At present, the methods used to detect ESBLs can be classified into 2 groups which are the phenotypic methods that use non-molecular techniques, which detect the ability of ESBL enzymes to hydrolyse different cephalosporins and the genotypic methods (Molecular methods) that use molecular techniques to detect the gene responsible for the production of ESBL. The aim of this work is to report the performance of cefepime clavulanate ESBL E-test for detection of ESBLs production in AmpC co-producing Klebsiella species. This study was conducted on thirty clinical isolates of Klebsiella species isolated from different clinical specimens referred to Central Microbiology Laboratory, Ain Shams University Hospitals for routine culture and susceptibility testing. Isolates from the same patient were excluded. All isolates of Klebsiella species were subjected to disk diffusion method using CTX,CAZ,CPD and FEP for screening of ESBLs production, Cephalosporin/ clavulanate combination disks, double disk synergy test and E-test by using CT/CTL, TZ/TZL and PM/PML for phenotypic confirmation. Screening of AmpC -Lactamase was done by disk diffusion method using Cefoxitin disk and Confirmation of AmpC -Lactamase is done by modified three dimensional test. Screening test for ESBL using CAZ, CTX and CPD by disk diffusion method showed 28 out of 30 studied isolates (93.33%) were determined to be resistant whereas 2 isolates (6.66%) were sensitive, while screening by using FEP 20 out of 30 isolates (66.66%) were resistant and 10 isolates (33.33%) were sensitive. Double disk synergy results showed 21 out of 30 isolates (70%) were positive ESBLs and 9 isolates (30%) were negative ESBLs. Combination disk test results shows 28 out of 30 isolates (93.33%) were ESBLs positive and 2 isolates (6.66%) were negative. CT/CTL E-test results shows 18 out of 30 isolates (60%) were ESBLs positive whereas 12 isolates (40%) were negative, while TZ/TZL E-test results shows 17 out of 30 isolates (56.66%) were ESBLs positive whereas 13 isolates were negative (43.34%) and PM/PML E -test results shows 29 out of 30 isolates (96.66%) were ESBLs positive and 1 isolate (3.33%) was negative. The sensitivity of PM/PML E- test in presence of AmpC is 100%, 37.5% for both CT/CTL E- test and TZ/TZL E- test and 50% for double disk synergy test.