COMPARISON OF PHENOTYPIC AND GENOTYPIC METHODS FOR DETECTION OF CARBAPENEM RESISTANCE IN AN INDIAN TERTIARY CARE HOSPITAL

Background:-Carbapenem-resistant Enterobacteriaceae (CRE) are a family of bacteria that can result in deadly infections because they are resistant to most antibiotics.Minimum inhibitory concentrations( MICs) are important in diagnostic laboratories to confirm resistance of microorganisms to an antimicrobial agent and also to monitor the activity of new antimicrobial agents whileas polymerase chain reaction confirms the detection of a particular gene . Aims & objectives:- To compare the MIC obtained by microbroth dilution method (BMD) with PCR for detection of blaKPC gene of the recovered isolates of Klebsiella pneumoniae. Material & Methods:-This study was conducted in the Department of Microbiology, Sher-i-Kashmir Institute of Medical Sciences, Srinagar; over a period of one year and three months.It included all isolates of Klebsiella pneumoniae recovered from blood culture of the patients. The identification and antimicrobial susceptibility was done on Vitek 2. Isolates that were resistant to meropenem were included for Microbroth dilution method for MIC and Conventional Polymerase Chain Reaction for blakpc gene.Results:-Minimum Inhibitory Concentration (MIC) was done on 55 Meropenem resistant isolates by Broth Microdilution test. A total of 20(36.3%) isolates had MIC of ?256 µg/ml followed by 18(32.7%) isolates with a MIC of 128 µg/ml , followed by 11(20%) isolates with MIC of 64 µg/ml and 6(10.9%) isolates with MIC of 32 µg/ml . On comparison of MIC with PCR for blaKPC gene findings it was seen that out of 20 isolates with MIC ?256 , 18(90%) were positive for blaKPC gene , among isolates with MIC 128 µg/ml, 61% were positive for blaKPC gene . whereas isolates with MIC 64µg/ml 72.7% were positive for this gene and isolates with MIC 32 µg/ml, 66.7% were positive for the blaKPC gene.Conclusion: All the Klebsiella pneumoniae resistant isolates by vitek 2 were also having MIC in resistant range by BMD method and isolates positive for blaKPC gene are having higher MIC ranges.