Introduction–Carbapenem antibiotics are used to treat infections due to multidrug resistant Enterobacteriaceae. Carbapenemases are enzymes which hydrolyse β lactam antibiotics including β lactam/ β lactam inhibitor combinations and third generation cephalosporins and the Carbapenem antibiotics –Imipenem, Meropenem and Ertapenem. With the widespread use of higher antibiotics in obstetrics and gynaecology and the emergence of multidrug resistant bacteria especially Escherichia coli, detection in clinical laboratories becomes essential. There are multiple genes responsible for carbapenem resistance and identifying each in every isolate may not be worth as the treatment does not differ significantly.

Aims and Objectives–Detection and comparison of carbapenemases by phenotypic methods in Escherichia coli isolated from obstetric surgical site infections.

Materials and methods – AST of the isolates was performed by the Kirby –Bauer technique and the Imipenem zone diameters were interpreted using the CLSI 2015 guidelines.23 randomly selected Escherichia coli isolates were further tested by the Modified Hodge Test, the Carba NP test and AmpC production and compared .

Results–The Imipenem disk was non–susceptible in 16/23(69.57%).MHT was positive in 12/23(52.17%) of the strains, the Carba NP test was positive in 12/23(52.17%) and Amp C in 8/23(34.78%).The Imipenem disk diffusion test was able to detect carbapenemases as detected by Carba NP test and showed non–susceptibility in the presence of AmpC. MHT did not prove to be useful.

Conclusion– The phenotypic methods detect Carbapenemase, but not its class. Also there are chances of false positive and false negatives and these cannot be recommended for routine diagnostic laboratories.