Prevalence of Listeria monocytogenes in Idiazabal cheese.

INTRODUCTION Raw-milk cheese has been identified in risk assessment as a food of greater concern to public health due to listeriosis. OBJECTIVE To determine the prevalence and levels of Listeria monocytogenes in semi-hard Idiazabal cheese manufactured by different producers in the Basque Country at consumer level. METHODOLOGY A total of 51 Idiazabal cheese samples were obtained from 10 separate retail establishments, chosen by stratified random sampling. Samples were tested using the official standard ISO procedure 11290-1 for detection and enumeration methods. RESULTS AND CONCLUSION All cheese samples tested negative for L. monocytogenes. However, 9.8% tested positive for Listeria spp., different from L. monocytogenes. Positive samples came from two brands, two were natural and three were smoked. The presence of Listeria spss. suggests that the cheese making process and the hygiene whether at milking or during cheese making could be insufficient.