Detection of extended spectrum beta-lactamases (ESBLS) producers in clinical isolates

Abstract

Background: Treatment of extended Spectrum β-lactamase (ESBL) producing gram negative bacilli is an increasing problem in hospitalized patients. Increasing resistance to third generation cephalosporins among gram negative bacilli has important therapeutic and clinical implications. ESBL producers significantly affect the course and outcome of infection and are associated with increased morbidity and mortality. The high proportion of ESBL producers and the outbreak of multi drug resistant gram negative bacilli are quite alarming and need expensive control measures. Appropriate laboratory detection is important to avoid inappropriate antimicrobial therapy. Aims & Objectives: The present study was undertaken to investigate the high incidence of extended Spectrum β-lactamases (ESBLS) producers and their antibiotic susceptibility pattern. Materials and Methods: A total of 228 GNB isolates, were studied for ESBL production. The isolates were screened for ESBL production by the double disc synergy test (DDST) as recommended by the Clinical Laboratory Standards Institute (CLSI). Antimicrobial susceptibility testing was done along with screening for ESBL production for commonly used antibiotics. Isolates which showed positive results were confirmed by phenotypic confirmatory disc diffusion test (PCDDT). Results: Out of 228 GNB isolates studied, 102 (44.73%) isolates were positive for ESBL production by presumptive screening test, of which 84 (36.84%) isolates were confirmed by PCDDT. The isolates of Escherichia coli (71.6%) were the most common ESBL producers, followed by K. pneumoniae (22.6%) and others. Imipenem (94.45%) was the most active and reliable agent for the treatment of the infections which were caused by the ESBL producing organisms. Conclusion: ESBL detection and antibiotic sensitivity testing should be undertaken routinely to avoid misuse of antibiotics and also prevent spread of these strains.