Detection of vancomycin resistance in enterococcus species isolated from clinical samples and feces of colonized patients by phenotypic and genotypic methods.
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Date
2016-04
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Abstract
Background: The aim of this study was to find out the clinical correlation
between the presence of vancomycin‑resistant genes (van A and van B) and
their expression as detected by phenotypic tests in colonized patients and in
clinical isolates. Materials and Methods: Enterococci were isolated from various
clinical samples and also from fecal specimens of colonized patients at the time
of admission, after 48 h and after 5 days of admission. Identification to species
level was done using standard methods. Vancomycin susceptibility in Enterococci
was detected by disc diffusion test. Minimum inhibitory concentration was
determined by agar dilution method. Multiplex polymerase chain reaction (PCR)
was used to detect the presence of van genes. Results: Out of all the clinical
and fecal samples processed, 12.0% isolates were either vancomycin resistant
or vancomycin intermediate. Further, these isolates carried van A or van B
genes as confirmed by PCR methods. Expression of van A gene was found
to be more in Enterococcus faecalis (28.3%) as compared to Enterococcus
faecium (25.0%) in both clinical and fecal isolates. 16.6% strains of E. faecium
and 15.0% strains each of E. faecalis and Enterococcus gallinarum were
found to carry van B genes. The overall prevalence of vancomycin resistant
Enterococci (VRE) in colonized patients was about 9.6%. Prior administration
of antibiotics had significant effect (P = 0.001) on VRE carriage. Urinary tract
infection was the most common infection caused by vancomycin susceptible
Enterococci (VSE), 105/214 (49.0%) and VRE, 13/36 (36.1%). There was no
significant difference (P = 0.112) in the distribution of VRE and VSE in different
infection types. Both clinical and fecal VRE showed maximum resistance to
penicillin, ampicillin, and piperacillin. Resistance to linezolid was 2.8% in clinically
isolated VRE. Conclusion: VRE in our study were found to be resistant to a
number of commonly used antibiotics. The frequency of isolation of vancomycin
resistant E. faecalis (VRE.fs), which is highly virulent, and the number of strains
harboring van A gene in our hospital setup is high and needs to be addressed.
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Keywords
Van A, van B, vancomycin resistant Enterococci
Citation
Biswas Priyanka Paul, Dey S, Adhikari L, Sen Aninda. Detection of vancomycin resistance in enterococcus species isolated from clinical samples and feces of colonized patients by phenotypic and genotypic methods. Indian Journal of Pathology & Microbiology. 2016 Apr-June 59(2): 188-193.