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CORRESPONDENCE
Year : 2014  |  Volume : 32  |  Issue : 1  |  Page : 89-90
 

Detection of Vancomycin resistant Enterococci with vanA genotype in clinical isolates from a tertiary care centre


1 Department of Microbiology, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani, India
2 Department of Paediatric Nephrology ,Institute of Child Health, Egmore, Chennai, Tamil Nadu, India

Date of Submission16-May-2013
Date of Acceptance29-Sep-2013
Date of Web Publication4-Jan-2014

Correspondence Address:
S S Ramesh
Department of Microbiology, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0255-0857.124339

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How to cite this article:
Padmasini E, Padmaraj R, Ramesh S S. Detection of Vancomycin resistant Enterococci with vanA genotype in clinical isolates from a tertiary care centre. Indian J Med Microbiol 2014;32:89-90

How to cite this URL:
Padmasini E, Padmaraj R, Ramesh S S. Detection of Vancomycin resistant Enterococci with vanA genotype in clinical isolates from a tertiary care centre. Indian J Med Microbiol [serial online] 2014 [cited 2019 Aug 17];32:89-90. Available from: http://www.ijmm.org/text.asp?2014/32/1/89/124339


Dear Editor,

Vancomycin is a glycopeptide increasingly used in treatment as an alternative choice to penicillin, aminoglycoside combination for the treatment of enterococcal infections. Resistance to vancomycin is now widely reported worldwide after its first appearance in 1988. Dissemination of vancomycin resistance can occur through both clonal expansion of VRE and horizontal transfer of van genes to other bacteria. Glycopeptide-resistant genotypes in enterococci include vanA, vanB, vanC1/C2/C3, vanD, vanE, vanG, vanL, vanM and vanN. Multiple epidemics have been predominantly reported with vanA type [1]. vanA gene cluster is located within transposon Tn1546 and can be transferred through acquired resistance.

A total of 43 non-identical clinical isolates of enterococci obtained from a tertiary care centre, Chennai, India. The specimen sources of isolates include blood, urine and pus. Enterococci were identified using standard identification methods [2] . The antibiotic susceptibility testing was done by Kirby-Bauer disc diffusion method. Enterococcus faecalis ATCC 29212 was used as control strain. The results were interpreted according to CLSI guidelines, 2011 [Table 1]. MIC for vancomycin was determined by both agar dilution method (CLSI guidelines, 2011) [3] and HiComb MIC strip (HiMedia Laboratories, Mumbai, India) method to screen for vancomycin resistance in enterococci. The specific vancomycin-resistant genotype vanA and vanB were determined by polymerase chain reaction (PCR) using primers (Sigma Aldrich, USA) and cycling conditions as described previously [4] with minor modifications in annealing condition (58°C for 1 min) and reducing the cycling conditions for 32 cycles. 38/43 (88.3%) were identified as E. faecalis (29 from blood and 3 from urine), 7/43 (16.2%) were Enterococcus faecium (from blood), 2 (4.6%) were Enterococcus casseliflavus (from blood) and 1 (2.3%) Enterococcus avium (from pus specimen). E. faecalis was the predominant isolate obtained in the present study followed by E. faecium. One E. faecalis and one E. faecium obtained from blood were detected as VRE with an MIC range of 128 μg/ml and 256 μg/ml [Figure 1] constituting 4.6% (2/43) and they carried vanA gene [Figure 2]. Accession number: KF311229 was obtained for our vanA gene PCR product from GenBank. This isolate (Efm090) was used as positive control for analysis of other isolates.
Table 1: Antibiotic resistance among enterococcal isolates by disc diffusion method

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Figure 1: HiComb MIC Strip with MIC >256ƒÊg/ml for vancomycin in Efm090 isolate

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Figure 2: Multiplex PCR analysis of vancomycin resistance genes in representative enterococcal isolates

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Further, the sensitivity pattern of isolates revealed, 29/43 (67.4%) isolates were multiple drug resistant to more than one class of antibiotics. These isolates also exhibited high level resistance to aminoglycosides upon agar screening method. Surprisingly, all the isolates were susceptible to ampicillin on MIC; though they were resistant on disc diffusion method. Interestingly, all strains were susceptible to linezolid and teicoplanin by disc diffusion method. Although 2 VRE were obtained, they were also susceptible (≥14 mm) to teicoplanin (30 mcg Himedia disc); however, this should be further confirmed by MIC to prove its susceptibility. Since, these strains were vanA gene positive, these patients may not respond to teicoplanin. The genotype identification is more rapid than conventional methods. The antibiotic history of the patients had showed that these patients were treated with vancomycin, cloxacillin, amikacin and cephalosporin intravenously. However, the present study found a very good sensitivity for linezolid, the treatment option for VRE and MRSA. VRE is now frequently being reported in India. A recent study from Chennai [5] has reported VRE in 18 isolates (4%) which had been treated with linezolid. Considering the increasing frequency of VRE isolation from different parts of India; appropriate surveillance, continuous monitoring is very important to control the spread and cross contamination of these resistant clones.

 
 ~ References Top

1.Cattoir V, Leclercq R. Twenty-five years of shared life with vancomycin resistant enterococci: Is it time to divorce? J Antimicrob Chemother 2013;68:731-42.  Back to cited text no. 1
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2.Washnigton W, Allen S, Janda W, Koneman E, Procop G, Schreckenberger P, Woods G. Koneman's colour atlas and Textbook of diagnostic microbiology. 6 th ed. 2006. p. 732-3.  Back to cited text no. 2
    
3.Performance standards for antimicrobial susceptibility testing; CLSI 21 st informational supplement. Vol. 31. Wayne, PA: CLSI; 2011. p. M100-S21.  Back to cited text no. 3
    
4.Bell MJ, Paton CJ, Turnidge J. Emergence of vancomycin resistant enterococci in Australia: Phenotypic and genotypic characteristics of isolates. J Clin Microbiol 1998;36:2187-90.  Back to cited text no. 4
    
5.Vidyalakshmi PR, Gopalakrishnan R, Ramasubramanian V, Abdul Ghafur K, Nambi PS, Thirunarayana MA. Clinical, epidemiological and microbiological profile of patients with vancomycin-resistant enterococci from a Tertiary Care Hospital. J Global Infect Dis 2012;4:137-8.  Back to cited text no. 5
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