Real-time PCR-based detection of Coxiella burnetii in cheeses

• DOI: 10.1007/s00217-012-1855-z
• Publication Date: 2012-12-22T16:33:40Z
• Authors: Federico Capuano; Andrea Mancusi; Francesco Casalin...; Anna Perugini; Yolande Proroga; Achille Guarino; Mustapha Berri
• Keywords: Coxiella burnetii; Q fever; SYBR Green I; Sheep milk

In this study, the presence of Coxiella burnetii (Cb) in cheese produced in Southern Italy from milk of cow, buffalo, and small ruminants has been evaluated. Two tests based on real-time PCR assay targeting CB IS1111 element were performed. First an assay based on the use of Taq-Man probe was performed to screen the samples. The positive samples were confirmed using both a SyBr Green test and the evaluation of the melting temperature of the amplicons. In addition, all cheese samples were also tested to determine the milk species utilized (Regulation EC 273/2008). The samples of cheese produced with a milk mix from different species were not included into the study. A total of 169 cheese samples were tested, and the obtained results showed an overall prevalence of Cb of 21.3 % with variation between species. A positivity rate of 39 % was observed in cow’s cheese while Cb DNA was detected in 26 % of cheese samples made from small ruminants’ milk. However, the bacterium was found only in 6.9 % of buffalo’s cheese samples. A direct association between prevalence and milk used for the production was highlighted (χ 2 = 19.12). The statistical analysis of the prevalence in the samples from cattle and small ruminants compared with those from buffalo shows an OR of 8.4 and 4.9, respectively.