International Journal of Current Microbiology and Applied Sciences (IJCMAS)
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National Academy of Agricultural Sciences (NAAS)
NAAS Score: *5.38 (2019)
[Effective from January 1, 2019]
For more details click here

ICV 2018: 95.39
Index Copernicus ICI Journals Master List 2017 - IJCMAS--ICV 2018: 95.39
For more details click here

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PRINT ISSN : 2319-7692
Online ISSN : 2319-7706
Issues : 12 per year
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Editor-in-chief: Dr.M.Prakash
Index Copernicus ICV 2018: 95.39
NAAS RATING 2020: 5.38

Int.J.Curr.Microbiol.App.Sci.2016.5(7): 234-241

Phenotypic Detection of Different Resistance Mechanism of Imipenem Resistance among Clinical Isolates of Enterobacteriaceae
M.Swetha*, K. Anuradha and Kiran Kavatagi
Department of Microbiology, Mysuru medical college and research institute, Mysuru, Karnataka, India
*Corresponding author

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.

Keywords: Carbapenemases,Modified Hodge Test,MBL,AmpC.
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How to cite this article:

Swetha, M., K. Anuradha and Kiran Kavatagi. 2016. Phenotypic Detection of Different Resistance Mechanism of Imipenem Resistance among Clinical Isolates of Enterobacteriaceae.Int.J.Curr.Microbiol.App.Sci. 5(7): 234-241. doi: