Original Research Article
Year: 2019 | Month: July-September | Volume: 4 | Issue: 3 | Pages: 93-102
Comparison of Molecular and Conventional Methods in the Detection of Carbapenem Resistance in Gram Negative Bacilli
Mangayarkarasi V1, Sneka P2, Stephen PM3
1Professor, Department of Microbiology, AIIMS, Mangalagiri, Vijayawada, Andhra Pradesh- 522503
2Associate Professor, Department of Microbiology, Bharath Medical College, Bharath University, Selaiyur- 600073. Tamil Nadu.
3Postgraduate, Department of Microbiology, SRM Medical College Hospital and Research Centre, Kattankulathur- 603203, Tamil Nadu.
ABSTRACT
Aim: To assess the role of Carba NP as a standalone test in the detection of carbapenem resistance in Gram negative bacilli (GNB) compared to other phenotypic and molecular methods.
Materials and Methods: A total of 170 Gram Negative Bacilli (GNB) isolated from the 340 clinical samples like urine, pus, tissue, blood, sputum and tracheal aspirate were used for the study. We did antibiotic susceptibility testing by Kirby bauer disk diffusion test to detect carbapenem resistance and compared Epsilometer strip test (E test), Modified Hodge Test (MHT) and Multiplex Polymerase Chain Reaction ( PCR).
Results: Of the 170 Gram negative bacilli isolated 18.2% (31/170) showed resistance to one or more of the carbapenem drugs tested i.e. Ertapenem, Meropenem, Doripenem and Imipenem. Escherichia coli (E. coli) showed maximum presence of carbapenemase with bla OXA 48 being the predominant gene. CarbaNP test had a sensitivity of 87% in detecting carbapenemase activity when compared with other conventional techniques such as Modified Hodge test and Kirby Bauer Disk Diffusion. Among the carbapenemase producing Gram negative Bacteria bla NDM, bla OXA 48 and bla IMP were demonstrated by molecular diagnostic methods using Multiplex PCR.
Conclusion: CarbaNp is a cost effective and rapid screening test in detection of Carbapenem resistant enterobacteriaceae (CRE)
Key words: CarbaNP test, Gram negative bacteria, Kirby bauer test, Modified Hodge test, PCR.