Detection of Extended Spectrum Beta Lactamases from Clinical Samples

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Jashmi Chandraker, Ashish Saraf


Background and objective Extended spectrum beta-lactamases (ESBLs) are a rapidly evolving group of beta-lactamase which share the ability to hydrolyze third generation cephalosporins and aztreonam but are inhibited by clavulanic acid. Their detection is essential for proper antibiotic therapy, to limit the spread of resistance mechanisms and for epidemiological purposes. This study was to determine the detection of ESBL to know the best suitable one in our lab setup.

Material and method: The total of 53 Gram negative isolates were identified based on the different biochemical test as per the standard protocol and Antibiotic susceptibility testing (AST) was done. ESBL production was observed which were resistant to one of the third generation cephalosporins were selected provisionally as ESBL producers and then subjected for confirmation by Phenotypic confirmatory Double Disk Synergy Test (30 mm), Double Disk Synergy Test (20 mm), Modify Double Disk (20), ESBL E-Test to evaluate their ability to detect ESBLs.

Result:  In case of ESBL E test the 16 ESBL production was observed and highest sensitivity was observed in case of Cefepime only. In case of DDST (30mm) 14 ESBL production was observed and specificity in cefepime was 82% and further increased upto 84% in case of cefepime combination. DDST (20mm) 15 ESBL production was observed again the sensitivity was high for Cefepime alone (87%), while in combination it was 87% and 89% with Ceftazidime and Cefotaxime. MDDST (20mm) identified 16 isolates as ESBL, resulting the sensitivity of 91%.

Conclusion: In this study we noticed that E. coli shows maximum ESBLs production and cefepime is most effective cephalosporins for detection of ESBL followed by cefotaxime, ceftazidime and cefpodoxime. This sensitivity of the test can be further improved with MDDST

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