Prevalence of TEM, SHV, and CTX-M Beta-Lactamase genes in the urinary isolates of a tertiary care hospital

Abstract

Introduction: Extended-spectrum beta-lactamases (ESBLs) are the major cause of resistance to beta-lactam antibiotics such as penicillins, cephalosporins, and monobactams. They are derived from the narrow-spectrum beta-lactamases (TEM-1, TEM-2, or SHV-1) by mutations that alter the amino acid configuration around the enzyme active site. Aim: To determine the prevalence of ESBL (bla TEM , bla CTX-M , and bla SHV ) genes among the members of Enterobacteriaceae. Methodology: The present prospective study was carried out from January 2015 to June 2015 in the Department of Microbiology and Molecular Medicine of a Teaching Tertiary Care Hospital. A total of 526 urine samples were studied. Seventy-eight isolates were subjected to polymerase chain reaction for detection of ESBL genes. Results: In our study, ESBL genes were detected among 18 (45%) phenotypically confirmed ESBL producers and 20 (52.5%) phenotypically confirmed non-ESBL producers. The gene that predominated was bla TEM (48.7%), followed by bla CTX-M (7.6%) and bla SHV (5.1%). Conclusion: Definitive identification of ESBL genes is only possible by molecular detection methods. Phenotypic tests need to be evaluated periodically as their performance may change with the introduction of new enzymes.

Keywords

• beta-lactam antibiotics
• extended-spectrum beta-lactamases
• polymerase chain reaction