A comparative study of modified Hodge test and Carba NP test for detecting carbapenemase production in Gram-negative bacteria

Abstract

Objective: The aim of this study was to evaluate the efficacy of the modified Hodge test (MHT) and Carba NP test for the detection of carbapenemase production on Gram-negative bacilli (GNB). Materials and Methods: A total of 816 well-characterized GNB isolated from various clinical samples received from both out- and hospitalized patients were included in the study. Out of those, 16.18% (132/816) were carbapenem-resistant on screening test. MHT and Carba NP test were carried out on all these carbapenem-resistant GNB isolates. Results: Out of the 132 isolates screened resistant during the study period, 75% (99/132) were positive for MHT and 86.4% (114/132) showed the presence of carbapenemase by Carba NP test. Conclusion: The advantage of the Carba NP test over MHT is that it is a rapid test where the results can be read in short time and it is easy to perform. The number of detected carbapenemase producers was significantly higher by Carba NP test though this finding can only be validated by molecular analysis of the strains.