Clostridioides difficile'nin pastörize süt, yoğurt ve kefirdeki davranışı ve nisinin etkisi
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Date
2024-01-08
Authors
Dal, Ayşe Gül
Journal Title
Journal ISSN
Volume Title
Publisher
Bursa Uludağ Üniversitesi
Abstract
Çoklu ilaç direncine sahip olan ve nozokomiyal bir patojen olarak bilinen Clostridioides difficile tedavisi zor enfeksiyonlara yol açmaktadır. Son yıllarda toplum ilişkili vakalardaki artış, etkenin zoonoz özelliğine ve gıdalar yolu ile bulaşma şekline dikkatleri çekmiştir. Çalışmamızda klasik kültürel yöntemleri kullanarak etkenin sporlarının pastörize inek sütünde, yoğurtta ve kefirde canlılığı ve davranışı depolama süresince izlenmiştir. İnoküle edilen sporların süt ürünlerinden geri kazanımında kayıpların yüksek olduğu ve etkenin % 90'dan fazlasının kullanılan besiyerinde yeniden çimlendirilemediği saptanmıştır. Sporların uygulanan pastörizasyon işlemlerinden etkilenmediği, ayrıca depolama süresi boyunca pastörize süt, yoğurt ve kefir örneklerinde anlamlı bir yıkımlanmaya maruz kalmaksızın canlılığını sürdürdüğü belirlenmiştir. Bazı gram pozitif bakteriler ile sporlar üzerine inhibe etkisi olduğu bilinen bir bakteriyosin olan nisinin etkisini belirlemek amacıyla, farklı dozlardaki (7,5-12,5-25-50 ppm) Nisin A pastörizasyon sonrası süte ilave edilmiş ve depolama süresince sporlar üzerine etkisi incelenmiştir. Farklı Nisin A inokülasyon düzeylerinde etkenin tamamen yıkımlanamadığı, en yüksek yıkımlanmanın 25 ve 50 ppm nisin eklenen gruplarda sırasıyla 1,80 log ve 1,83 log olarak gerçekleştiği saptanmıştır. 50 ppm uygulanan gruptaki yıkımlanma ilk analiz gününde kontrol grubuna göre yaklaşık 1 log seviyesinde ölçülmüştür. Sonuç olarak, etkenin sporlarının süt ürünlerinden geri kazanımının düşük olduğunu, buna neden olan koşulların incelenmesi gerekliliğini ortaya koymaktadır. Ayrıca ısıya ve depolama koşullarına dirençli olan sporların, gıdalar vasıtasıyla insanlara bulaşmada önemli ve etkin rol oynayabileceğini işaret etmektedir. Diğer sporlu basillus ve klostridialardan farklı olarak üzerinde nispeten daha az çalışma ve bilgi bulunan C. difficile hakkında kapsamlı ve multidisipliner çalışmaların yapılması halk sağlığı açısından bir gereklilik olarak görülmektedir.
Clostridioides difficile, which has multidrug resistance and is known as a nosocomial pathogen, causes infections that are difficult to treat. The increase in community-related cases in recent years has drawn attention to the zoonotic nature of the pathogen and its food-related transmission properties. In the present study, the viability and behaviour of the spores were monitored in pasteurized cow's milk, yoghurt and kefir during the storage period using classical cultural methods. It is important to notice that losses in the recovery of inoculated spores from dairy products were more than 90% thus, the spores could not be re-germinated in the medium used. The spores were resistant to employed pasteurization processes and their viability was not affected during the storage period in pasteurized milk, yoghurt and kefir samples. To determine the effect of nisin, a bacteriocin known to have a detrimental effect on some gram-positive bacteria and spores, the milk was first inoculated with spores then pasteurized and Nisin A added at different doses (7.5-12.5-25-50 ppm). The spores could not be destroyed at the tested concentrations. On the first analysis day, approximately 1 log decrease was measured with 50 ppm. The highest destruction was 1.80 log and 1.83 log in the groups where 25 and 50 ppm nisin were added, respectively. The results obtained from our thesis study reveal that the recovery rate of spores from dairy products is too low and the conditions leading to this recovery loss should be scrutinized. It is also provided evidence that spores that are resistant to heat and storage, may have an important and effective role in the transmission of pathogen to humans through food. From the public health point of view, comprehensive and multidisciplinary studies are necessary to better understand the role of foodstuffs in the contamination route and pathogenicity of C. difficile since the actual knowledge acquired is relatively few compared to other spore-forming bacilli and clostridia.
Clostridioides difficile, which has multidrug resistance and is known as a nosocomial pathogen, causes infections that are difficult to treat. The increase in community-related cases in recent years has drawn attention to the zoonotic nature of the pathogen and its food-related transmission properties. In the present study, the viability and behaviour of the spores were monitored in pasteurized cow's milk, yoghurt and kefir during the storage period using classical cultural methods. It is important to notice that losses in the recovery of inoculated spores from dairy products were more than 90% thus, the spores could not be re-germinated in the medium used. The spores were resistant to employed pasteurization processes and their viability was not affected during the storage period in pasteurized milk, yoghurt and kefir samples. To determine the effect of nisin, a bacteriocin known to have a detrimental effect on some gram-positive bacteria and spores, the milk was first inoculated with spores then pasteurized and Nisin A added at different doses (7.5-12.5-25-50 ppm). The spores could not be destroyed at the tested concentrations. On the first analysis day, approximately 1 log decrease was measured with 50 ppm. The highest destruction was 1.80 log and 1.83 log in the groups where 25 and 50 ppm nisin were added, respectively. The results obtained from our thesis study reveal that the recovery rate of spores from dairy products is too low and the conditions leading to this recovery loss should be scrutinized. It is also provided evidence that spores that are resistant to heat and storage, may have an important and effective role in the transmission of pathogen to humans through food. From the public health point of view, comprehensive and multidisciplinary studies are necessary to better understand the role of foodstuffs in the contamination route and pathogenicity of C. difficile since the actual knowledge acquired is relatively few compared to other spore-forming bacilli and clostridia.
Description
Keywords
C. difficile, Kefir, Nisin, Pastörize süt, Yoğurt, Pasteurized milk, Yoghurt
Citation
Dal, A. G. (2024). Clostridioides difficile'nin pastörize süt, yoğurt ve kefirdeki davranışı ve nisinin etkisi. Yayınlanmamış doktora tezi. Bursa Uludağ Üniversitesi Sağlık Bilimleri Enstitüsü.