In-house Carba NP - II test to identify and differentiate carbapenemase-producing Gram-negative bacteria among various clinical isolates in comparison with immunochromatography assay

Abstract

Resistance to Carbapenems has increased drastically resulting in ineffective treatment, prolonged hospital-stay, increased morbidity and mortality. A cost-effective in-house test that can differentiate carbapenemase enzymes belonging to different Amblers Class can emerge as an important tool in middle and low-income countries for guiding the clinicians in selecting the most appropriate antibacterial therapy. Cost effective commercial ICT kits are also available now for the same use.1. To adapt an in-house test that can identify and differentiate Ambler class carbapenemase enzymes among the clinical isolates of multi-drug resistant Gram-negative bacteria (GNB); 2. To evaluate the commercially available immunochromatography (ICT) lateral flow assay of carbapenemase detection in comparison to in-house Carba NP – II testA prospective study conducted in the Department of Microbiology of NRI Institute of Medical Sciences, Visakhapatnam. All GNB isolates irrespective of source, age and gender, were considered in the study. A total of 565 GNB isolates were obtained, which were subsequently tested for Meropenem resistance by routine antimicrobial susceptibility test (AST), out of which 195 isolates were further tested for carbapenemase resistance by in-house Carba NP - II test and ICT (Bio-State Inc).Out of 565 isolates, 195 were Meropenem resistant, 120 belonged to Class B and 75 to Class D by in-house modified Carba NP-II test. In ICT, 117 belonged to Class B and 73 to Class D and 5 isolates showed both the enzymes of Class B and D. No class A enzyme was detected in our study by either method.Carba NP - II Test is a reliable and cost-effective test with similar results in comparison to commercially available ICT.