Evaluation of CIVA agar for rapid detection of extended spectrum beta- lactamases (ESBL) among isolates of Enterobacteriaceae.

The emergence of plasmid mediated extended spectrum b-lactamases (ESBLs) in members of family Enterobacteriaceae has become a worldwide problem. Many clinical microbiology laboratories make no effort to detect ESBL production by Gram negative bacilli and have problem to detect ESBL mediated resistance. The choice of optimal laboratory method for detection and surveillance of ESBL producing organisms is still not clear. ESBLs are encoded on conjugative plasmids, transposons or integrons and these elements are readily spread under selective antibiotic pressure. Failure to detect ESBL mediated resistance has contributed to uncontrolled spread of ESBL producers and related treatment failures. Identification of ESBLs, based on phenotypic test is the strategy most commonly used in clinical laboratories. Standard methods for detection of ESBL in clinical isolates namely double disk synergy test, National Committee for Clinical Laboratory Standards (NCCLS) phenotypic confirmatory test (using cephalosporin/clavulanate combination disks), broth micro dilution assay and E test ESBL strip are time consuming and not easily performed. Since a simple method for rapid detection of ESBLs from clinical specimens of patients with severe infection is urgently needed, the present study was undertaken to evaluate the use of a screening medium CIVA agar (ceftazidime, inositol, vancomycin, amphotericin B) for rapid detection of ESBLs among isolates of Enterobacteriaceae.