Approaches of veterinarians toward treatment of mastitis and investigation of the role of antibiotics used for treatment in the development of resistance in field isolates
Open Veterinary Journal, cilt.16, sa.9, ss.6267-6282, 2026 (ESCI, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 16 Sayı: 9
- Basım Tarihi: 2026
- Doi Numarası: 10.5455/ovj.2026.v16.i9.34
- Dergi Adı: Open Veterinary Journal
- Derginin Tarandığı İndeksler: Emerging Sources Citation Index (ESCI), Scopus
- Sayfa Sayıları: ss.6267-6282
- Anahtar Kelimeler: Antimicrobial resistance, Escherichia coli, Questionnaire survey, Staphylococcus aureus, Veterinarians
- Hatay Mustafa Kemal Üniversitesi Adresli: Hayır
Özet
Background: Increasing antimicrobial resistance poses a serious threat to both animal and human health. Identifying the factors that play a role in resistance will contribute to the development of preventive measures and strategies to address this problem. Aim: This study investigated the roles of veterinarians’ approaches to the treatment of mastitis in dairy cows and the effects of antimicrobial compounds used in field isolates on the development of resistance. Methods: A face-to-face questionnaire was administered to determine the approaches of veterinarians to the treatment of mastitis, the challenges they faced in treatment, and the antimicrobial compounds they used. In addition, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were isolated and identified from the milk samples of 248 cows with mastitis on 60 farms across 26 different regions in two provinces located in eastern Turkey, and their resistance to the antimicrobial compounds used by veterinarians in the field was determined by the disc diffusion. Antimicrobial usage and resistance percentages were standardized by z-score and analyzed using K-means clustering, with the four-cluster solution selected based on silhouette analysis. Results: The questionnaire survey revealed that mastitis was treated by veterinarians based on clinical signs and their own experience. They were often forced to use multiple antimicrobial compounds due to treatment difficulties, but despite this, the treatment of mastitis resulted in failure in most cases. A large majority of veterinarians stated that they were willing to perform microbiological cultures and antibiograms if available, but they noted a lack of adequate laboratory services. The results of the antimicrobial susceptibility testing conducted on E. coli isolates revealed that the highest resistance rate (93.2%) was observed against ampicillin-sulbactam, whereas no resistance was detected against ertapenem, tigecycline, and nitrofurantoin. Among S. aureus isolates obtained from milk samples with mastitis, the highest resistance rate was 100% against benzylpenicillin, followed by erythromycin (78%), clindamycin (75%), and lincomycin (74%). Although some commonly used antimicrobials (amoxicillin and penicillin) were highly resistant, K-means analysis identified a low-use–high-resistance profile (Cluster II), with significantly higher resistance rates in both E. coli (p < 0.05) and S. aureus (p < 0.001). Furthermore, high resistance was detected to antimicrobial compounds mostly used in human medicine rather than for treating mastitis or other ruminant diseases, including rifampicin, linezolid, tobramycin, and levofloxacin. Conclusion: Although the extensive use of antimicrobial compounds can lead to antimicrobial resistance, in this study, no direct link was established between the use of antimicrobial compounds in the treatment of mastitis and the development of resistance in bacteria. Given that many factors play a role in the development of antimicrobial resistance (AMR), the issue must be addressed with a holistic approach to implement necessary measures. In this study, the detection of high resistance to critically important antimicrobial compounds used in human medicine underlines the urgent need for new regulatory measures in this area in some countries, including Turkey.