Molecular Identification, Biofilm Formation Ability and Antimicrobial Resistance of Staphylococcus warneri Isolates Obtained from Mastitic Cows in the Aegean Region

Year 2026, Volume: 37 Issue: 1, 98 - 103, 29.03.2026

Serhan Akgöz , Çağatay Nuhay , Emine Çiler Çimenlidağ Adalıoğlu , Aliye Ebru Çelik , Ceren Halıcı Demir , Aslı Kılıç , Nizamettin Yücedağ

https://doi.org/10.36483/vanvetj.1849676

https://izlik.org/JA66FN84KJ

Abstract

Staphylococcus warneri is a species belonging to the coagulase-negative staphylococci (CoNS) group and is commonly found as a commensal organism on the skin and mucosal surfaces of humans and animals. In recent years, the increasing isolation rates of CoNS from milk and dairy products have highlighted their significance in terms of both food safety and livestock production. This study aimed to confirm S. warneri isolates obtained from milk samples using molecular methods, to evaluate their biofilm-forming ability through the Congo Red Agar (CRA) method, and to determine their phenotypic antimicrobial resistance profiles. For this purpose, 650 milk samples were examined, the presence of S. warneri was investigated using phenotypic identification methods, and suspected isolates were confirmed by Polymerase Chain Reaction (PCR). The biofilm-forming ability of isolates identified as S. warneri was assessed on CRA medium. In addition, the susceptibility of the isolates to eight different antibiotics was determined by the Kirby-Bauer disk diffusion method according to CLSI standards. Among the 650 samples analyzed, 21 isolates were found to be positive for S. warneri, and all isolates demonstrated biofilm-forming capacity. According to the antibiotic susceptibility results, the isolates exhibited resistance to oxacillin (90.5%), trimethoprim–sulfamethoxazole (81.0%), penicillin (47.6%), tetracycline (38.1%), chloramphenicol (23.8%), erythromycin (14.3%), and doxycycline (14.3%), while all isolates were fully susceptible to gentamicin (100%). In conclusion, the presence of S. warneri, a CoNS species, in dairy cattle within the sampling region was confirmed; their biofilm-forming abilities were determined; and the most appropriate antibiotic options for treatment were evaluated phenotypically based on resistance profiles.

Keywords

Antibiotic Resistance , Biofilm , Staphylococcus warneri

Ethical Statement

For the implementation of the study, an application was submitted to the Animal Experiments Ethics Committee of the Bornova Veterinary Control Institute. The Committee stated in its decision dated 18.12.2025 and numbered 2025/6 that ethical approval was not required for this research.

Ege Bölgesindeki Mastitisli Sığırlardan İzole Edilen Staphylococcus warneri Suşlarında Moleküler Tanımlama, Biyofilm Oluşturma Yeteneği ve Antimikrobiyal Direncin Değerlendirilmesi

https://izlik.org/JA66FN84KJ

Abstract

Staphylococcus warneri, koagulaz-negatif stafilokoklar (KNS) arasında yer alan ve insan ile hayvanların deri ve mukozalarında kommensal olarak bulunan bir türdür. Son yıllarda süt ve süt ürünlerinde KNS türlerinin artan oranlarda izole edilmesi, bu bakterilerin hem gıda güvenliği hem de hayvansal üretim açısından önemini artırmıştır. Bu çalışma, süt örneklerinden izole edilen Staphylococcus warneri suşlarının moleküler yöntemlerle doğrulanması, biyofilm oluşturma kapasitelerinin Congo Red Agar (CRA) yöntemiyle değerlendirilmesi ve antimikrobiyal direnç profillerinin fenotipik olarak ortaya konması amacıyla yürütülmüştür. Bu amaçla 650 süt örneği incelenmiş, fenotipik yöntemlerle S. warneri varlığı araştırılmış ve şüpheli izolatlar PCR ile doğrulanmıştır. S. warneri olarak tanımlanan izolatların biyofilm oluşturma yeteneği CRA besiyeri kullanılarak değerlendirilmiştir. Ayrıca izolatların sekiz farklı antibiyotiğe karşı duyarlılığı CLSI standartlarına göre Kirby-Bauer disk difüzyon yöntemi ile belirlenmiştir. Çalışmada 650 örnekten elde edilen 21 izolatın S. warneri yönünden pozitif olduğu ve tüm izolatların biyofilm oluşturma yeteneğine sahip olduğu tespit edilmiştir. Antibiyotik duyarlılık sonuçlarına göre izolatlarda %90.5 oksasilin, %81.0 trimetoprim-sülfametoksazol, %47.6 penisilin, %38.1 tetrasiklin, %23.8 kloramfenikol, %14.3 eritromisin ve doksisiklin direnci görülürken; tüm izolatların gentamisine karşı %100 duyarlı olduğu belirlenmiştir. Sonuç olarak, örnekleme bölgesindeki süt sığırlarında KNS türlerinden S. warneri varlığı ortaya konulmuş, biyofilm oluşturma kapasiteleri belirlenmiş ve tedavide kullanılabilecek en uygun antibiyotik seçenekleri fenotipik olarak değerlendirilmiştir.

Keywords

Antibiyotik Direnci , Biyofilm , Staphylococcus warneri

Ethical Statement

Çalışmanın uygulanması için Bornova Veteriner Kontrol Enstitüsü Hayvan Deneyleri Etik Kurulu'na başvuru yapılmıştır. Kurul, 18.12.2025 tarihli ve 2025/6 numaralı kararında bu araştırma için etik onayının gerekli olmadığını belirtmiştir.

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