**7. Conclusion**

In the present study, all MBL – E test positive *E.coli* strains (100%) were detected by Disk potentiation test also. MBL producing *E.coli* strains must be tested in both carbapenem resistant as well as sensitive strains by Disk potentiation method using Imipenem – EDTA. Disk potentiation method is simple to perform and materials used are cheap, non-toxic, and easily accessible and allowed for objective interpretation of results. It is also quite good in detecting carbapenem sensitive MBL producing strains.

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Beta-lactamase producing organisms are detected by E test, which is standard phenotypic method and also by Polymerase chain reaction (PCR) which is a gold standard, but both are costly and require expertise. Failure to detect these enzymes has contributed to their uncon‐ trolled spread and commonly to therapeutic failures.

Hence to conclude, for detection of ESBL, combined disk method using Ceftazidime / Cefta‐ zidime Clavulanic acid(CAZ/CAC), for detection of Amp C β-lactamases confirmatorty Disk potentiation test using Ceftazidime / Ceftazidime - 3-aminophenylboronic acid and for detection of Metallo β-lactamases(MBL) producing *E.coli*, disk potentiation test using Imipe‐ nem/Imipenem - EDTA should be done in both carbapenem sensitive as well as resistant isolates by all Clinical Microbiology Laboratories to prevent its dissemination and also for a good therapeutic outcome.
