Carba NP as a simpler, rapid, cost-effective, and a more sensitive alternative to other phenotypic tests for detection of carbapenem resistance in routine diagnostic laboratories

Abstract

PURPOSE: Resistance to carbapenems due to carbapenemases has been increasingly noticed in Enterobacteriaceae. Clinical and Laboratory Standards Institute (CLSI) has recommended the latest Carba NP (CNP) test as a confirmatory test for carbapenemase production in Enterobacteriaceae. Low sensitivity of disk diffusion (DD) and modified Hodge test (MHT) may result in missing out of resistant strains which can adversely affect clinical management. The present study compares three phenotypic tests - CNP test, DD, and MHT for detection of carbapenemase production.

MATERIALS AND METHODS: Four hundred consecutive, nonduplicate Enterobacteriaceae isolates were tested for carbapenem resistance using ertapenem disc (10 μg) by Kirby–Bauer DD method, MHT, and CNP. These tests were performed and interpreted as per the CLSI standards. CNP was considered to be the reference test for comparison. Sensitivity, specificity, and accuracy rates for ertapenem DD and MHT were calculated.

RESULTS: One hundred and six out of 400 strains were positive by CNP test. Of the 294 CNP-negative strains, 28 were resistant by DD and 18 were resistant by MHT. Of the 106 CNP-positive strains, 82 were resistant and 16 were intermediate by DD while 76 were positive by MHT ertapenem DD had a sensitivity and specificity of 66.04% and 90.48%, respectively. Sensitivity and specificity of MHT were 54.72% and 93.88%, respectively. There was considerable discordance between all the three tests.

CONCLUSION: As a rapid, simple, and cost-effective test with a greater capability greater to detect carbapenemase producers, CNP can be implemented in routine diagnostic laboratories, thereby benefiting patient care and antimicrobial stewardship.

Keywords

CarbaNP - carbapenemase - Hodge - rapid - resistance

Publication History

Received: 17 February 2016

Accepted: 02 August 2016

Article published online:
19 February 2020

• References

• 1 Currie B. The emergence of carbapenemase-producing Enterobacteriaceae. Infect Dis Spec Ed 2012;1:9-13.
• 2 Perez F, Van Duin D. Carbapenem-resistant Enterobacteriaceae: A menace to our most vulnerable patients. Cleve Clin J Med 2013;80:225-33.
• 3 Queenan AM, Bush K. Carbapenemases: The versatile beta-lactamases. Clin Microbiol Rev 2007;20:440-58.
• 4 Nordmann P, Naas T, Poirel L. Global spread of carbapenemase-producing Enterobacteriaceae. Emerg Infect Dis 2011;17:1791-8.
• 5 Jean SS, Hsueh PR. High burden of antimicrobial resistance in Asia. Int J Antimicrob Agents 2011;37:291-5.
• 6 Keynan Y, Rubinstein E. The changing face of Klebsiella pneumoniae infections in the community. Int J Antimicrob Agents 2007;30:385-9.
• 7 Clinical and Laboratory Standards Institute. Performance Standards for Antimicrobial Susceptibility Testing. 25^th Informational Supplement. CLSI Document M100-S25. Wayne, PA: Clinical and Laboratory Standards Institute; 2015.
• 8 Nordmann P, Poirel L, Dortet L. Rapid detection of carbapenemase-producing Enterobacteriaceae. Emerg Infect Dis 2012;18:1503-7.
• 9 Winn W Jr., Allen S, Janda W, Koneman E, Procop G, Schreckenberger P, et al. Koneman's Color Atlas and Textbook of Diagnostic Microbiology. 6^th ed. United States of America: Lippincott Williams & Wilkins; 2006. p. 213-93.
• 10 Galani I, Rekatsina PD, Hatzaki D, Plachouras D, Souli M, Giamarellou H. Evaluation of different laboratory tests for the detection of metallo-beta-lactamase production in Enterobacteriaceae. J Antimicrob Chemother 2008;61:548-53.
• 11 Hrabák J, Chudácková E, Papagiannitsis CC. Detection of carbapenemases in Enterobacteriaceae: A challenge for diagnostic microbiological laboratories. Clin Microbiol Infect 2014;20:839-53.
• 12 Anderson KF, Lonsway DR, Rasheed JK, Biddle J, Jensen B, McDougal LK, et al. Evaluation of methods to identify the Klebsiella pneumoniae carbapenemase in Enterobacteriaceae. J Clin Microbiol 2007;45:2723-5.
• 13 Nordmann P, Poirel L. Strategies for identification of carbapenemase-producing Enterobacteriaceae. J Antimicrob Chemother 2013;68:487-9.
• 14 Nordmann P, Gniadkowski M, Giske CG, Poirel L, Woodford N, Miriagou V; European Network on Carbapenemases. Identification and screening of carbapenemase-producing Enterobacteriaceae. Clin Microbiol Infect 2012;18:432-8.
• 15 Girlich D, Poirel L, Nordmann P. Value of the modified Hodge test for detection of emerging carbapenemases in Enterobacteriaceae. J Clin Microbiol 2012;50:477-9.
• 16 Cury AP, Andreazzi D, Maffucci M, Caiaffa-Junior HH, Rossi F. The modified Hodge test is a useful tool for ruling out Klebsiella pneumoniae carbapenemase. Clinics (Sao Paulo) 2012;67:1427-31.
• 17 Doyle D, Peirano G, Lascols C, Lloyd T, Church DL, Pitout JD. Laboratory detection of Enterobacteriaceae that produce carbapenemases. J Clin Microbiol 2012;50:3877-80.
• 18 Tijet N, Boyd D, Patel SN, Mulvey MR, Melano RG. Evaluation of the Carba NP test for rapid detection of carbapenemase-producing Enterobacteriaceae and Pseudomonas aeruginosa. Antimicrob Agents Chemother 2013;57:4578-80.
• 19 Vasoo S, Cunningham SA, Kohner PC, Simner PJ, Mandrekar JN, Lolans K, et al. Comparison of a novel, rapid chromogenic biochemical assay, the Carba NP test, with the modified Hodge test for detection of carbapenemase-producing Gram-negative bacilli. J Clin Microbiol 2013;51:3097-101.