Phenotypic Detection of High-Level Aminoglycoside Resistance (HLAR) in Enterococcus Species in a Tertiary Care Centre

S. Revathy¹*, K. S. Sridharan², A. S. Elumalai ³ And Umasekar³  

¹Department of Biochemistry and Biotechnology, Annamalai University, Chidhambaram (India).

²Department of Microbiology, Sri Ramachandra University, Chennai - 116 (India).

³Department of Plant Biology and Biotechnology, Presidency College, Chennai - 005 (India).

ABSTRACT: Enterococcus is one of the important causes of hospital acquired infections. Drug resistance particularly for High Level Aminoglycosides Resistance is one of the important patterns of resistance exhibited by Enterococcus. This study was conducted to determine the high-level aminoglycoside resistance for gentamicin and streptomycin in Enterococcal species isolated from a tertiary care centre. Number of isolates collected were 76 of which 42 (55.2%) from urine 26(34.21%) from exudates, 4(5.26%) from blood and rest from other body fluids. Most of the isolates were Enterococcus faecalis (72%) followed by Enterococcus faecium (28%). All the isolates were subjected to Kirby-Bauer disk diffusion test using high-content gentamicin (120 μg/disk) and streptomycin (300 μg/disk), single concentration agar dilution test with streptomycin 2000 μg/ml, 500 μg/ml and 2000 μg/ml of gentamicin. There were 27 (35.5%) were showed High Level Aminoglycosides Resistance (HLAR), of which 18(23.68%) were High Level Gentamycin Resistance (HLGR), 9(11.84%) were High Level Streptomycin Resistance (HLSR) and 9 (11.84%) isolates showed resistant to both. E.faecalis was the species most frequently exhibited High Level Resistance (HLR) for the drugs tested. Prevalence of HLAR in Enterococci is high and could be a serious problem in a hospital setup, screening for high-level aminoglycoside resistance must be included in routine antibiotic susceptibility reporting for Enterococcal isolates, especially from blood as high-level resistant strains does not show synergism with cell wall acting antibiotics like penicillin group and vancomycin which are the drug of choice.

KEYWORDS: High-Level  Aminoglycoside Resistance (HLAR); Disk Diffusion test

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