Speciation of enterococcal isolates and antibiotic susceptibility test including high level aminoglycoside resistance and minimum inhibitory concentration for vancomycin.

Authors:Dr Narayan Shrihari, Dr. Kumudini T.S, Dr. S.G karadesai, Dr. S.C Metgud
Int J Biol Med Res. 2011; 2(4): 865 – 869  |  PDF File

Abstract

Abstract: Title: Speciation of Enterococcal isolates and antibiotic susceptibility test including high level aminoglycoside resistance and minimum inhibitory concentration for Vancomycin. Introduction: Enterococci have been considered as relatively low virulence but they are known to cause various clinical infections like urinary tract infections, endocarditis, intra abdominal and pelvic infections. The emergence of vancomycin resistant Enterococci (VRE) in addition to the increasing incidence of high level aminoglycoside resistance (HLAR), presents a serious challenge for clinicians treating the patients with infections due to Enterococci. Methods: A total of 54 Enterococcal isolates from various clinical samples were included and processed according to standard protocol and speciation was based on Facklams conventional method. Antibacterial susceptibility pattern was determined by Kirby Bauer disc diffusion method with recommended drugs including high level aminoglycoside resistance. Minimum inhibitory concentration (MIC) for vancomycin was done by agar dilution method. Results: E.faecalis was the predominant species isolated among various clinical samples. Among 25 urinary isolates 24 (96%) were E.faecalis and one (4%) was E.faecium. Similarly among 9 blood isolates 7 (77.78%) were E.faecalis and two (22.22%) were E.faecium. Out of 54 strains, 46.29% of isolates were resistant to ciprofloxacin, 31.48% for ampicillin and 29.62% for penicillin. E.faecium showed more resistance than E.faecalis for gentamicin and E.faecalis showed more resistance than E.faecium for streptomycin. All strains were susceptible to vancomycin and MIC between1 to4 µg/ml. Conclusion: E.faecalis is most common than E.faecium. Enterococcus species were susceptible to vancomycin with MIC ≤ 4 µg/ml.