Investigation of the Prevalence of vanA and vanB genes in vancomycin resistant enterococcus (VRE) by Taq Man real time PCR Assay

Abstract

Objective: Enterococci are important nosocomial agents and due to their potential antimicrobial resistance they have a significant role in the dissemination of resistance genes. Currently, these species are described as healthcare concern. The aim of this study was to determine vanA and vanB genes in vancomycin resistant enterococci (VRE) strains isolated from the various clinical samples in the hospitals in Iran. Methods: Susceptibility of 235 strains to vancomycin was screened as minimum inhibitory concentration (MIC) by E-test. The genes encoding modifying vancomycin precursor's dipeptide termini named as vanA and vanB genes were targeted by Taq Man real time PCR assay in vancomycin resistant and vancomycin intermediate resistant Enterococcus faecalis and Enterococcus faecium strains. Results: A total of 235 enterococci were isolated from the clinical specimens. One hundred and ninety three (82.1%) of them were defined as E. faecalis, 33 (14.0%) E. faecium, 1/235 (0.4%) E. avium, 1/235 (0.4%) E. raffinosus and 7/235 (3.0%) E. galinarium. The prevalence of vancomycin resistance was 13.6% (32/235) consisting of 18/235 (7.7%) E. faecalis and 6.0% (14/235) E. faecium. Among the 32 VRE strains, a total of 36 vanA and vanB genes were detected (some isolates had both vanA and vanB genes). These resistance genes were not detected in 5 out of 32 (15.6%) isolates. Conclusion: E. faecalis was more common in clinical samples and vanA (58.3%) gene was the predominant gene among the VRE isolates. The current study showed that Taq Man real time PCR assay is the useful, precise and rapid detection of vancomycin resistance genes.

Keywords

• VRE, Taq Man real time PCR, vanA, vanB, Enterococcus faecalis

Investigation of the Prevalence of vanA and vanB genes in vancomycin resistant enterococcus (VRE) by Taq Man real time PCR Assay

Öz

Amaç: Enterokoklar önemli hastane enfeksiyonu etkenidirler ve antimikrobiyal direnç potansiyelleri nedeniyle rezistans genlerinin yayılmasında önemli rolleri bulunmaktadır. Günümüzde bu mikroorganizmalar önemli bir halk sağlığı sorunu olarak tanımlanmıştır. Bu çalışmada İran’daki bazı hastanelerde değişik klinik örneklerden izole edilen vankomisin dirençli enterokok (VRE)’lar arasında vanA ve vanB genlerinin sıklığının araştırılması amaçlandı. Yöntemler: Suşların vankomisin duyarlılıkları E test yöntemiyle araştırılarak minimum inhibitör konsantrasyon (MİK) değerleri belirlendi. Vankomisin dirençli ve vankomisine orta düzeyde dirençli Enterococcus faecalis ve Enterococcus faecium suşlarında Taq Man real time PCR assay ile vankomisin direncini kodlayan vanA ve vanB genleri hedeflendi. Bulgular: Çalışma süresince klinik örneklerden toplam 235 enterokok suşu izole edildi. Bu şuşlardan 193’ü (% 82,1) E. faecalis, 33’ü (% 14,0) E. faecium, 1’i (% 0,4) Enterococcus avium, 1’i (% 0,4) Enterococcus raffinosus ve 7’si (% 3,0) Enterococcus galinarium olarak tanımlandı. Toplam 235 enterokok suşunda 32’si (% 13,6) VRE idi. Toplam 235 suştan 18 (% 7,7)’i E. faecalis ve 14’ü (% 6,0) E. faecium idi. Bu suşların 27 (% 84,4)’sinde vanA ve vanB genleri belirlendi (bazı izolatlar hem vanA ve hem vanB genlerine sahip idi). Suşların 5’inde (% 15,6) direnç geni belirlenemedi.Sonuçlar: Araştırmamızda klinik VRE suşları arasında E. faecalis suşlarının sıklıkta olduğu ve vanA geninin vankomisin direncine sebep olan en sık gen olduğu gözlendi. Bu çalışma Taq Man real time PCR assay testinin vankomisin direnç genlerinin gösterilmesinde kullanılabilen, kesin ve hızlı bir test olduğunu göstermektedir

Anahtar Kelimeler

• VRE, Taq Man real time PCR, vanA, vanB, Enterococcus faecalis, Enterococcus faecium

Kaynakça

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