The relationship between virulence factors and vancomycin resistance among Enterococci collected from food and human samples in Southern Turkey

Abstract

The aims of this research were to study the prevalence of potential virulence factors, vancomycin resistance and also to evaluate a possible correlation that can exist between vancomycin resistance and potential virulence factors between 51 Enterococcus spp. isolated from food and 50 Enterococcus faecium strains from human in southern Turkey. Identification of the isolates was determined by Vitek-II system. Antimicrobial susceptibility tests were performed by Vitek-II system and disc diffusion method. The presence of vanA and vanB as well as enterococcal virulence genes of cytolysin (cylA), the aggregation substance (asa1), gelatinase (gelE), enterococal surface protein (esp), hyaluronidase (hyl) were investigated by Polymerase Chain Reaction (PCR) method. Haemolysin production was also studied phenotypic method. Apart from one isolate, none of the food originated enterococci were resistant to vancomycin, and none carried vanA and vanB resistance genes. All clinical isolates were resistant to vancomycin and 84% of them carried vanA; 2%, vanB; and 14%, neither vanA nor vanB genes. Except for the cylA gene, all other virulence genes and vancomycin resistance were higher in human strains, and a positive correlation was observed between multivirulence genes and hemolytic activity. For all strains, a positive correlation existed between the esp gene positivity and vancomycin resistance, while for only E. faecium, esp, hyl gene positivity and vancomycin resistance a positive correlation could be seen. Furthermore, “silent cylA” genes were found in two food and one intestinal strains. Based on our findings, we can suggest that virulence increases in parallel to vancomycin resistance, and food may be a potential source for dissemination of gelE, asa1 and hyl virulence genes. Finally, esp and hyl genes presence should carefully be monitored in food originated enterococci

Keywords

• Enterococci
• relationship
• vancomycin resistance
• virulence factors

Türkiye’nin güneyinde gıda ve insan örneklerinden toplanan Enterokok izolatlarının vankomisindirenci ve virülans faktörleri arasındaki ilişki

Abstract

Bu çalışmanın amaçları, Türkiye’nin güneyinde gıda kaynaklı 51 adet Enterococcus spp. ile insan kaynaklı 50 adet Enterococcus faecium izolatlarının potansiyel virülans faktörlerinin, vankomisin direnç özelliklerinin prevalansının belirlenmesi ve vankomisin direnci ile virülans faktörler arasında muhtemel ilişkinin değerlendirilmesidir. İzolatlarının identifikasyonu Vitek-II sistemiyle, antimikrobiyel direnç testleri Vitek-II sistemi ve disk difüzyon metodlarıyla çalışıldı. vanA ve vanB ile sitolizin (cylA), agregasyon faktörü (asa1), jelatinaz (gelE), entrokok yüzey proteini (esp), hiyolüronidaz (hyl), genlerinden oluşan enterokokal virülans genler Polimeraz Zincir Reaksiyonu (PCR) metoduyla, hemolizin üretimi fenotipik yöntemle çalışıldı. Bir izolat dışında, gıda izolatlarının hiçbiri vankomisine dirençli değildi ve hiçbiri vanA ve vanB geni taşımamaktaydı. Klinik izolatların tümü vankomisine dirençliydi ve bu izolatların %84’ü vanA, %2’si vanB genlerini taşımakta; %14’ü vanA ve vanB genlerini taşımamaktaydı. cylA geni dışındaki test edilen diğer virülans genler ve vankomisin direnci, klinik izolatlarda daha yüksekti ve çoklu virülans genler ile vankomisin direnci arasında pozitif bir korelasyon gözlendi. Tüm izolatlar arasında esp gen pozitifliği ile vankomisin direnci, E. faecium türlerinde ise esp, hyl gen pozitiflikleri ile vankomisin direnci arasında pozitif bir korelasyon olduğu görüldü. Ayrıca, iki gıda ve bir intestinal enterokok suşunda ‘’sessiz cylA geni’’ bulundu. Bulgularımıza göre, virülans faktörler vankomisin direncine paralel olarak artabilir ve gıda kaynaklı enterokoklar gelE, asa1, hyl virülans genlerinin yayılmasında potansiyel kaynak olabilir. Sonuç olarak, gıda kaynaklı enterokoklarda esp ve hyl gen varlığı dikkatle izlenmelidir

Keywords

• Enterokok
• ilişki
• vankomisin direnci
• virülans faktörler

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