TULUM PEYNİRİNDEN Escherichia coli İZOLASYONU, PATOTİPLENDİRMESİ VE ANTİBİYOTİK DİRENÇ PROFİLLERİNİN BELİRLENMESİ

Öz

Çalışma kapsamında Isparta ve Konya illerindeki yerel pazarlardan temin edilen toplam 70 Tulum peyniri örneğinde Escherichia coli varlığı, patotip özellikleri ve antibiyotik direnç profilleri araştırılmıştır. Örneklerden kromojenik koliform agar kullanılarak toplam 25 muhtemel E. coli izolatı elde edilmiştir. İzolatların morfolojik tanısında Gram boyama, indol ve katalaz testleri uygulanmış; tüm izolatların Gram negatif çubuk morfolojisinde olduğu, indol ve katalaz pozitif reaksiyon verdiği belirlenmiştir. Moleküler doğrulama amacıyla gerçekleştirilen 16S rRNA temelli PCR analizlerinde, tüm izolatlarda E. coli’ye özgü 544 bç büyüklüğündeki hedef bölge tespit edilmiş ve peynir örneklerinin %35.71’inde E. coli varlığı doğrulanmıştır. Patotip araştırmalarında ise incelenen suşların hiçbirinde hedeflenen virülans genleri saptanmamış, bu nedenle izolatların kommensal veya patojenik olmayan E. coli olarak değerlendirilebileceği sonucuna ulaşılmıştır. Antibiyotik dirençlilik testlerinde izolatların tamamının eravasiklin, trimetoprim-sülfametoksazol, meropenem, aztreonam, amoksisilin-klavulanik asit, nitrofurantoin, sefoksitin, imipenem ve ampisiline duyarlı olduğu belirlenmiştir. Buna karşın en yüksek direnç oranı norfloksasine (%64) karşı saptanmış, bunu gentamisin (%52), amikasin (%36), seftriakson (%28) ve siprofloksasin (%28) izlemiştir. İzolatların önemli bir kısmının 2–5 antibiyotiğe dirençli olduğu belirlenmiştir. Çoklu antibiyotik direnç (MAR) indeks değerlerinin 0.000–0.312 arasında değişmesi, bazı suşların yoğun antibiyotik baskısına maruz kalmış yüksek riskli kaynaklardan köken almış olabileceğini göstermiştir. Elde edilen sonuçlar, geleneksel Tulum peynirlerinin hijyenik kalitesinin sürekli olarak izlenmesi gerektiğini ve antibiyotik dirençli E. coli suşlarının halk sağlığı açısından potansiyel bir risk oluşturabileceğini ortaya koymaktadır.

Anahtar Kelimeler

• Tulum peyniri
• Escherichia coli
• patotiplendirme
• antibiyotik direnç
• MAR indeksi

ISOLATION of Escherichia coli FROM TULUM CHEESE, PATHOTYPING, AND DETERMINATION OF ANTIBIOTIC RESISTANCE PROFILES

Öz

Within the scope of this study, the presence of Escherichia coli, its pathotype characteristics, and antimicrobial resistance profiles were investigated in a total of 70 Tulum cheese samples obtained from local markets in the provinces of Isparta and Konya, Türkiye. A total of 25 presumptive E. coli isolates were recovered using Chromogenic Coliform agar. Morphological characterization of the isolates was performed by Gram staining, indole, and catalase tests, revealing that all isolates exhibited Gram-negative rod morphology and were positive for both indole and catalase reactions. For molecular confirmation, 16S rRNA gene-based PCR analyses were conducted, and the E. coli-specific 544 bp target fragment was detected in all isolates. Consequently, E. coli was detected in 35.71% of the cheese samples examined. In the pathotype analyses, none of the investigated isolates carried the targeted virulence genes, indicating that these strains could be considered commensal or non-pathogenic E. coli. Antimicrobial resistance testing demonstrated that all isolates were susceptible to eravacycline, trimethoprim-sulfamethoxazole, meropenem, aztreonam, amoxicillin-clavulanic acid, nitrofurantoin, cefoxitin, imipenem, and ampicillin. In contrast, the highest resistance rate was observed against norfloxacin (64%), followed by gentamicin (52%), amikacin (36%), ceftriaxone, and ciprofloxacin (28% each). A considerable proportion of the isolates exhibited resistance to two to five antibiotics. Multiple antibiotic resistance (MAR) index values ranged from 0.0 to 0.312, suggesting that some strains may have originated from high-risk sources exposed to intensive antibiotic pressure. Overall, these findings highlight the need for continuous monitoring of traditional Tulum cheeses with respect to hygienic quality and indicate that the presence of antibiotic-resistant E. coli strains may represent a potential public health concern.

Anahtar Kelimeler

• Tulum cheese
• Escherichia coli
• pathotyping
• antibiotic resistance
• MAR index

Kaynakça

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