Occurrence of the CTX-M, SHV and the TEM Genes Among the Extended Spectrum b-Lactamase Producing Isolates of Enterobacteriaceae in a Tertiary Care Hospital of North India

Purpose: The present study was carried out to assess the prevalence of the Extended Spectrum Beta Lactamases (ESBLs) and to characterize the ESBL types which were prevalent in our hospital. Material Methods: Five hundred gram negative isolates which belonged to the family, Enterobacteriaceae, which were isolated during the study period of 2009 to 2011, were investigated for ESBL production. Clinical isolates from urine (344), pus (109), blood (15), IV/central line tip (10), sputum (12) and body fluid (10) specimens were processed. The organisms which were identified, included E. coli (351), Klebsiella pneumoniae (74), Klebsiella oxytoca (21), Proteus mirabilis (15), Proteus vulgaris (9), Enterobacter spp (15) and Citrobacterspp (15). Antimicrobial susceptibility testing was done. The ESBL detection was carried out for all the isolates by the CLSI confirmatory method. The MIC of ceftazidime and ceftazidime plus clavulanic acid was determined by the E-test. Molecular typing of the ESBLs was performed by multiplex PCR among 93 ESBL isolates. Results: 45.8% isolates were found to be ESBL producers by the CLSI confirmatory method and they were confirmed by the E-test ESBL strips. A majority of E. coli in the study possessed the CTX-M genes (59.32%). Among the Klebsiella isolates, a majority were co producers of the ESBL genes; either 2 or all the 3 genes co-existed together. Conclusion: An indiscriminate use of the higher antibiotics should be restricted as far as possible. The infection control programmes should be monitored continuously in hospitals, to contain these ESBL producers. We are reporting the presence of all types of ESBL genes among the Enterobacteriaceae isolates from our hospital setting.