| prevalence, types, and geographical distribution of listeria monocytogenes from a survey of retail queso fresco and associated cheese processing plants and dairy farms in sonora, mexico. | in the first part of this study, samples were collected from farms, cheese processing plants (cpps), and retail markets located in various geographical areas of sonora, mexico, over a 12-month period during the summer of 2004 and winter of 2005. four (all queso fresco [qf] from retail markets) of 349 total samples tested positive for listeria monocytogenes (lm). of these four positive samples, three were collected in the northern region and one in the southern region of sonora. additionally, two ... | 2007 | 18044440 |