Murat GÜLMEZ, Ethem BAZ, Abamüslüm GÜVEN

The use of novobiocin and cefixime-tellurite in broth, and of cefixime-tellurite, salicin, rhamnose and MUG in agar medium for the detection of Escherichia coli 0157:H7 in ground beef

Dondurulmuş kıymalarda Escherichia co//0157:H7 araştırmada kullanılan lauryl tryptose (LST) buyyon ve HC (Hemorrhagic colitis £ coli strains) ağarın selektivitesi artırılmaya çalışıldı. LST buyyonun selektivitesi novobiyosin (20 mg/l) içeren LST (LST + n) buyyondan daha yüksek bulundu, fakat novobiyosin, sefiksim (0,05 mg/l) ve tellurit (2,5 mg/l) içeren LST (LST + net) buyyon zenginleştirme besiyeri olarak uygun bulunmadı. Sorbitol pozitif suşlar sorbitol negatif suşlara kıyasla novobiyosine anlamlı derecede daha dirençli bulundular (P < 0,05). Sonuç olarak, kıymaların LST gibi saplementsiz uygun bir besiyerinde zenginleştirilmesi, ve sonra da bu kültürden ve bu kültürün ilk üç ondalık seri seyreltisinden yeteri miktarda alınarak ramnoz ve sorbitol bazlı sefiksim-telluritli HC agar gibi bir katı besiyerine ekilmesi rutin bir kültür yöntemi olarak önerilebilir nitelikte bulunmuştur. Eosin methylene blue (EMB) ağarın metalik yansıma özelliği CTR-HC ağara transfer edilebilinirse analiz süresini bir gün kısaltacak olan bu besiyeri mevcut besiyerlerine alternatif olabilir. Şalisin veya 4-methylumbelliferyl-p-D glucuronide (MUG)'in rutin kültür yöntemlerinde kullanılması gerekli bulunmadı.

Kıymadan Escherichia coli 0157:H7 araştırmak amacıyla sıvı besiyerinde novobiyosin ve sefiksim-tellurit ve katı besiyerinde sefiksim-tellurit, salisin, ramnoz ve MUG' un kullanılmı

We aimed to improve the selectivity of lauryl tryptose (1ST) broth and HC (hemorrhagic colitis Escherichia col! strains) agar for the detection of £ col i 0157:H7 in frozen ground beef samples. The selectivity of LST broth was superior to that of LST containing novobiocin (20 mg/l) (LST + n), but LST containing novobiocin, cefixime (0.05 mg/l) and tellurite (2.5 mg/l) (LST + net) was found to be unsuitable as an enrichment medium. The sorbitol positive strains were significantly more resistant to novobiocin than were the sorbitol negative strains (P < 0.05). As a result, the enrichment of ground beef samples in a selective broth without antibiotics such as LST, and then spread plating a subsequent amount from this original enrichment culture and the first three 10-fold serial dilutions onto a rhamnose and sorbitol based selective medium such as cefixime-tellurite HC medium (CTR-HC) was found to be recommendable as a routine cultural method. Transferring the metallic sheen property of eosin methylene blue (EMB) agar to CTR-HC agar can represent an alternative to the available media, and this will shorten the analysis time by 1 day. Use of salicine or 4-methylumbelliferyl-p-D glucuronide appears unnecessary in routine cultural techniques.

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