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Indian Journal of Microbiology Research

Detection of carbapenamase production by rapid carba NP test among Enterobacteriaceae isolates in tertiary care hospital

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Research Article

Author Details : Kanagiri Tejasvi, B Anuradha*

Volume : 6, Issue : 3, Year : 2019

Article Page : 272-276

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Introduction: The spread of carbapenemase producers is the most important clinical issue in antibiotic
resistance in gram negative bacteria particularly Enterobacteriaceae. There is an utmost importance of
rapid detection. Several phenotypic and genotypic tests are present for detection of carbapenemases but
are time consuming, require expertise and well established laboratory. Our study aims at detection of
carbapenemase production by rapid Carba NP test
Materials and Methods: A prospective study of two months duration was done among 150
Enterobacteriaceae species (Escherichia coli 88, Klebsiella pneumonia 49 and others 13) isolated from
various cli nical samples in a teritiary care Hospital. Strains were first identified by standard phenotypic
methods. Resistance to carbapenems was detected using Ertapenem (10mcg) disk by Kirby Bauer disk
diffusion method and Carba NP test as per the CLSI standards. Carba NP test is based on the detection of
Imipenem hydrolysis by carbapenemase producing bacteria. Hydrolysis acidifies the medium which results
in colour change of the pH indicator.
Results: Among 150 isolates, Carba NP positive 34(22.6%) and negative 116(77.3%). Ertapenem disk
diffusion detected 122(81.3%) as susceptible, 8(5.3%) as intermediate and 20(13.3 %) as resistant. Carba
NP has a sensitivity (61.76%), specificity (93.97%), PPV (75%), NPV (89.34%), accuracy (86.67%) which
are statistically significant with ‘p’ value <0> Conclusion: CNP detects larger number of carbapenemases within shorter time (<2h> diffusion (16-18h) which is rapid, highly specific, accurate and gives result in single day with minimal

Keywords: Carba NP, Ertapenem carabapenemase rapid.

Doi : 10.18231/j.ijmr.2019.059

How to cite : Tejasvi K, Anuradha B, Detection of carbapenamase production by rapid carba NP test among Enterobacteriaceae isolates in tertiary care hospital. Indian J Microbiol Res 2019;6(3):272-276

Copyright © 2019 by author(s) and Indian J Microbiol Res. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0) (