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PRINT ISSN : 2319-7692
Online ISSN : 2319-7706 Issues : 12 per year Publisher : Excellent Publishers Email : editorijcmas@gmail.com / submit@ijcmas.com Editor-in-chief: Dr.M.Prakash Index Copernicus ICV 2018: 95.39 NAAS RATING 2020: 5.38 |
Carbapenems are the mainstay in the management of infections by multi-drug resistant (MDR) Enterobacteriaceae. However, there are reports of increasing prevalence of carbapenem resistance in clinical isolates of Enterobacteriaceae mainly due to the production of metallo-β-carbapenemases (MBL), Klebsiella pneumoniae carbapenemase (KPC) and AmpC β-lactamases (AmpC). A simple and inexpensive testing method for screening of carbapenemase producers is essential. The aim of the present study is to determine phenotypically the presence of different resistance mechanism among imipenem resistant Enterobacteriaceae. The prospective study screened all Enterobacteriaceae isolated from blood, tracheal aspirate, urine and pus aspirates which were submitted to the microbiology laboratory. The isolates were screened according to susceptibility zone size < 23mm of Imipenem on Kirby-Bauer disc diffusion method. The screened isolates were subjected to phenotypic assay Modified Hodge Test, combined Imipenem EDTA and Imipenem phenylboronic acid disc diffusion test, AmpC disc test were used for the detection of carbapenemases, MBL, KPC and AmpC β-lactamases, respectively. A total of 100 Imipenem resistant Enterobacteriaceae isolates comprising Klebsiella pneumoniae 37 (37%); Escherichia coli 32 (32%); Citrobacter freundii 7(7%); Enterobacter sps 19(19%);Proteus mirabilis 5(5%) were included in the study. Out of the 100 isolates,39 (39%) found positive for carbapenemases by modified Hodge test, 43 (43%) were MBL producers by combined Imipenem EDTA disc diffusion test, 45 (45%) were KPC producers by combined Imipenem phenylboronic acid disc diffusion test, 38 (38%) were AmpC β-lactamase producers. KPC production was a predominant mechanism of carbapenem resistance among Klebsiella pneumoniae(67.6%), MBL production in case of Escherichia coli(65.6%), AmpC β-lactamases production among Enterobacter sps (63.2%), Citrobacter freundii(71.4%),Proteus mirabilis(60%).Boronic acid–based inhibition testing for KPC detection and Combined Imipenem- EDTA disc test for detection of Metallo- β -lactamases (MBL) were found to be effective. Use of both MHT and combined imipenem EDTA and imipenem phenylboronic acid disc diffusion test as a screening method can increase the sensitivity of detection of carbapenemases. AmpC β-lactamase is also a contributory factor for carbapenem resistance among Enterobacteriaceae.