Detection of Tem & Shv Genes in Extended Spectrum Beta Lactamase (esbl) Producing E.coli & Klebsiella Pneumoniae Isolated from a Tertiary Care Cancer Hospital

Introduction: Extended-spectrum beta-lactamases (ESBLs) are rapidly evolving group of beta-lactamase enzymes commonly produced by the Gram negative bacteria, these enzymes have been derived from TEM and SHV genes by mutations. This study was done to look for TEM and SHV genes in ESBL positive E.coli and K. pneumoniae isolated from the cancer patients suffering with infections and admitted in a tertiary care cancer hospital. Methods: A total of 156 clinical isolates of E. coli (n=80) and K. pneumonia (n=76) isolated from various clinical samples received in microbiology laboratory over a period of six months from May to October 2012. All the isolates were tested for ESBL production as recommended by the Clinical Laboratory Standard Institute (CLSI) by double disc diffusion screening test and by ESBL E-Test. Multiplex PCR was performed specific for TEM and SHV genes. Results: In this study 64.10% (100/156) of the isolates were ESBL producers with highest(65.7%) incidence among K. pneumoniae. All the ESBL positive isolates were selected for multiplex PCR for TEM and SHV genes of which 44% E.coli were positive for TEM gene alone, 4% positive for both TEM and SHV genes, 52% of E. coli were negative for both TEM and SHV genes. In case of K. pneumoniae 76% were positive for both TEM and SHV genes, 20% for SHV gene alone and 4% were positive for TEM gene alone. Conclusion: Our findings showed that majority of E.coli were negative for both TEM and SHV genes probably associated with other genes producing ESBL. Such molecular studies should be done in different regions of India to find the common ESBL enzymes present in that geographical area for epidemiological purposes.