Detection of carbapenemase production in Enterobacteriaceae and Pseudomonas species by carbapenemase Nordmann–Poirel test

PURPOSE: Multidrug-resistant organisms causing community-acquired and hospital-acquired infections are increasing at a dangerous rate. Carbapenemase-producing Enterobacteriaceae and Pseudomonas species are an important source of concern since these organisms are not only resistant to beta-lactam antibiotics but also show cross-resistance to other groups of antibiotics. In the present study, rapid detection of these carbapenemase-producing Enterobacteriaceae and Pseudomonas species by carbapenemase Nordmann–Poirel (Carba NP) test was evaluated by comparing with modified Hodge test (MHT). MATERIALS AND METHODS: Imipenem-resistant Enterobacteriaceae and Pseudomonas species isolated from various samples such as pus, blood, sputum, urine, and endotracheal aspirates were processed for carbapenemase detection by MHT and Carba NP test. Kappa analysis was done to evaluate the percentage agreement between the two tests. RESULTS: Seventy imipenem-resistant Enterobacteriaceae and Pseudomonas isolates were analyzed in the present study for carbapenemase production. 63.41% of Enterobacteriaceae and 34.48% of Pseudomonas species were carbapenemase producers considering both the methods. By MHT, 36 (51.42%) isolates and, by Carba NP test, 35 (50%) isolates were positive for carbapenemase production out of the 70 isolates. CONCLUSION: Carba NP test when compared to MHT is a simple, rapid, cost-effective biochemical test which can be used in all laboratories in the identification of life-threatening carbapenemase-producing Gram-negative bacteria.