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Published on: October 25, 2013
A Study on Glycopeptide-Resistant Genotypes among Clinical Isolates of Enterococcus with Van B Phenotype
1Department of Microbiology, Vinayaka Mission's Kirupananda Variyar Medical College, Salem, Tamil Nadu, India.
Background:
Enterococci, although remarked as harmless commensals of the intestinal tract of humans and animals, have become a significant source of infection in hospitalized patients worldwide.The present study aimed to isolate and identify enterococci from clinical samples and to determine the genotypic characteristics of vancomycin-resistant enterococcus isolates.
Materials And Methods:
A total of 774 isolates of enterococci from clinical samples were identified to the species level, and their anti-microbial susceptibility pattern was determined by Kirby Bauer Disk Diffusion method and Vitek 2 automated system. Screening for vancomycin resistance was performed by using brain heart infusion agar containing 6 micrograms/ml of vancomycin. The minimum inhibitory concentration (MIC) of vancomycin was determined by the agar dilution method and Epsilometer test (E test). Genotyping was carried out for resistant isolates by multiplex polymerase chain reaction.
Results:
Thirty (3.88%) isolates were resistant to vancomycin by agar screen method. Five isolates showed intermediate resistance with anMIC of 8-16 micrograms/ml for vancomycin by agar dilution. By the E test, two isolates displayed an MIC of ≥32 micrograms/ml for vancomycin and one isolate showed an MICof ≥32 micrograms/ml for teicoplanin.Van A was the common genotype isolated. The present study reports isolates of Enterococcus faecalis with a susceptible MIC for glycopeptide and the presence of the Van A gene.
Conclusion:
Heterogeneous resistance among clinical isolates of Enterococcus faecalis was observed in our study. The predominant phenotype and genotype detected among clinical isolates were Van A.
Insights
Vancomycin-resistant Enterococcus (VRE) infections are a growing concern in hospitals. This study identified VRE in clinical samples, finding the Van A genotype to be predominant, even in some susceptible isolates.
Area of Science:
- Microbiology
- Infectious Diseases
- Clinical Science
Background:
- Enterococci, typically harmless gut bacteria, are increasingly causing infections in hospitalized patients globally.
- This necessitates understanding their resistance mechanisms and prevalence.
Purpose of the Study:
- To isolate and identify enterococci from clinical samples.
- To characterize the genotypic features of vancomycin-resistant enterococcus (VRE) isolates.
Main Methods:
- Identified 774 enterococcal isolates from clinical samples.
- Determined antimicrobial susceptibility using Kirby Bauer Disk Diffusion and Vitek 2.
- Screened for vancomycin resistance using brain heart infusion agar and determined Minimum Inhibitory Concentration (MIC) via agar dilution and E test.
- Genotyped resistant isolates using multiplex polymerase chain reaction.
Main Results:
- Identified 3.88% vancomycin-resistant enterococcal isolates.
- Van A genotype was the most common.
- Reported Enterococcus faecalis isolates with susceptible glycopeptide MICs alongside the Van A gene.
Conclusions:
- Observed heterogeneous vancomycin resistance in clinical Enterococcus faecalis isolates.
- The Van A genotype and phenotype were predominant among these clinical isolates.
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