Journal of Clinical and Diagnostic Research [serial online

ABSTRACT Purpose The incidence of Extended Spectrum β -Lactamase (ESBL) producing strains among clinical Klebsiella species and Escherichia coli isolates has been steadily increasing over the past years. ESBL producing organisms pose a major problem for clinical therapeutics. Identifying organisms that are ESBL producers are a major challenge for the clinical microbiology laboratory. An attempt was therefore made to study ESBL production and multidrug resistance in clinical isolates of K.pneumoniae and E.coli at a hospital in Mangalore. Method ESBL production and multidrug resistance was studied in a total of 228 isolates of K.pneumoniae and E.coli which were obtained from various clinical samples during one year period from January to December 2008. Identification of the isolates was done based on cultural characteristics and reactions in standard biochemical tests. All the isolates were tested for antimicrobial susceptibility by the disk diffusion technique according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The screening for ESBL production was done by the phenotypic confirmatory test using ceftazidime discs in the presence and absence of clavulanic acid. Result All the isolates showed resistance or decreased susceptibility to at least one of the third generation cephalosporins (ceftazidime, cefotaxime, ceftriaxone) which were used for the study. ESBL production was noted in 59.65% of the isolates tested. ESBL production was detected in 51.47% strains of E.coli and 48.53% strains of K.pneumoniae (70% of E.coli isolated from urine samples and 75% of K.pneumoniae isolated from exudates samples were ESBL producers). All the isolates were found to be sensitive to the antibiotic, imipenem. Sensitivity of E.coli to piperacillin-tazobactum (Pt) and cefaperazone-sulbactum (Cfs) was 100%, whereas K.pneumoniae showed 98% sensitive to Pt and 88% sensitive to Cfs. Conclusion The study has shown an increase in the incidence of ESBL producing E.coli and K.pneumoniae strains in Mangalore. The prevalence of ESBL and multidrug resistant strains constitute a serious threat to the current β-lactam therapy. Tests for the detection of ESBL producing bacteria should be carried out at all diagnostic centers routinely and the use of third generation cephalosporins should be restricted. This can reduce the prevalence of ESBL producing organisms