GeneXpert vanA/vanB test and culture method in evaluation of Vancomycin Resistant Enterococcus (VRE) colonisation in a tertiary hospital

Abstract

Background: Enterococci are responsible for various nosocomial infections. The spread of vancomycin-resistant enterococci (VRE) especially in intensive care units (ICU) is a major threat in hospitals. Determination of VRE colonisers is crucial in order to prevent spreading of VRE. It was aimed to determine the colonisation of VRE among ICU patients by GeneXpert vanA/vanB test and culture method in a period of two years.
Method: From April 2015 to March 2017, a total of 788 rectal swab specimens were obtained from 292 ICU patients hospitalized at Dicle University hospitals. Swab samples were evaluated for VanA and VanB genes by GeneXpert® vanA / vanB, (Cepheid, USA) real time polymerase chain reaction (Rt-PCR) commercial system. Enterococcosel agar with 8 μg/mL vancomycin was used for cultivation of the samples. Swab samples were inoculated at 37°C, in aerobic condition for 48 hours. The growing bacteria were identified by Maldi Biotyper (Bruker, Germany) and antimicrobial susceptibilities were carried by BD Phoenix (Becton Dickinson, U.S.A) authomated microbiology system.
Results:Among 788 swab samples 116 (14,7%) were detected as VRE with GeneXpert vanA/vanB method. Of PCR positive samples, 107 (92,2%) were VanA, 7 (6%) were VanB and 2 (1,7%) were both VanA and VanB harbouring. Among VanA detected samples, 75 grew Enterococcus faecium, 8 grew Enterococcus faecalis isolates while 24 samples had no growth in cultivation. Among 7 VanB harbouring samples, 1 was identified as E. faecium while other 6 had no growth.Two samples with both VanA and VanB genes were isolated as E. faecium.
Conclusion: Active VRE surveillance and isolation of VRE carriers is crucial in hospitals. Molecular methods have important advantages in early diagnosis and on time isolation of the patients.

Keywords

• vancomycin-resistant enterococci,vanA / vanB

References

1. 1. Courvalin P. Vancomycin Resistance in Gram-Positive Cocci. Clin Infect Dis 2006;42(Supplement_1):25–34.
2. 2. Rice LB. Emergence of vancomycin-resistant enterococci. Emerg Infect Dis 2001;7(2):183–7.
3. 3. Tacconelli E, Cataldo MA. Vancomycin-resistant enterococci (VRE): transmission and control. Int J Antimicrob Agents 2008;31(2):99–106.
4. 4. Marner ES, Wolk DM, Carr J, et al. Diagnostic accuracy of the Cepheid GeneXpert vanA/vanB assay ver. 1.0 to detect the vanA and vanB vancomycin resistance genes in Enterococcus from perianal specimens. Diagn Microbiol Infect Dis 2011;69(4):382–9.
5. 5. Stamper PD, Cai M, Lema C, Eskey K, Carroll KC. Comparison of the BD GeneOhm VanR assay to culture for identification of vancomycin-resistant enterococci in rectal and stool specimens. J Clin Microbiol 2007;45(10):3360–5.
6. 6. Bourdon N, Bérenger R, Lepoultier R, et al. Rapid detection of vancomycin-resistant enterococci from rectal swabs by the Cepheid Xpert vanA/vanB assay. Diagn Microbiol Infect Dis 2010;67(3):291–3.
7. 7. EUCAST. The European Committee on Antimicrobial Susceptibility Testing. Breakpoint tables for interpretation of MICs and zone diameters. Version 6.0 [Internet]. 2016 [cited 2018 Mar 6]. Available from: http://www.eucast.org/ast_of_bacteria/previous_versions_of_documents/
8. 8. Uttley AH, Collins CH, Naidoo J, George RC. Vancomycin-resistant enterococci. Lancet 1988;1(8575–6):57–8.

9. 9. Woodford N. Glycopeptide-resistant enterococci: a decade of experience. J Med Microbiol 1998;47(10):849–62.
10. 10. Ostrowsky BE, Trick WE, Sohn AH, et al. Control of Vancomycin-Resistant Enterococcus in Health Care Facilities in a Region. N Engl J Med 2001;344(19):1427–33.
11. 11. Paule SM, Trick WE, Tenover FC, et al. Comparison of PCR assay to culture for surveillance detection of vancomycin-resistant enterococci. J Clin Microbiol 2003;41(10):4805–7.
12. 12. Holzknecht BJ, Hansen DS, Nielsen L, Kailow A, Jarløv JO. Screening for vancomycin-resistant enterococci with Xpert® vanA/vanB: diagnostic accuracy and impact on infection control decision making. New microbes new Infect 2017;16:54–9.
13. 13. Uludağ Altun H, Ataman Hatipoğlu Ç, Bulut C, Köseoğlu Eser Ö, Demiröz AP. Vankomisine Dirençli Enterokokların Sürveyansında GeneXpert® vanA/vanB PCR Sistemi ile Kültür Yönteminin Karşılaştırılması. Mikrobiyol Bul 2014;48(4):538–44.
14. 14. Zhou X, Arends JP, Kampinga GA, et al. Evaluation of the Xpert vanA/vanB Assay Using Enriched Inoculated Broths for Direct Detection of vanB Vancomycin-Resistant Enterococci. J Clin Microbiol 2014;52(12):4293–7.
15. 15. Babady NE, Gilhuley K, Cianciminio-Bordelon D, Tang Y-W. Performance Characteristics of the Cepheid Xpert vanA Assay for Rapid Identification of Patients at High Risk for Carriage of Vancomycin-Resistant Enterococci. J Clin Microbiol 2012;50(11):3659–63.