Villalón, a Fresh Ewe's Milk Spanish Cheese, as a Source of Potentially Pathogenic Aeromonas Strains.

Presumptive aeromonads were detected in 8 batches of Villalón cheese produced in dairy plants from pasteurized ewe's milk, the mean count being 2.85 ± 0.24 log CFU/g. Only four isolates from 2 batches were confirmed as motile aeromonads and they fitted the description of Aeromonas hydrophila . During cheese making of 5 batches of farmhouse-made raw milk Villalón cheese, presumptive aeromonads decreased in numbers from 3.6 log CFU/ml in raw ewes' milk to 2.2 log CFU/g after salting, but after storage for 48 h at 4°C, multiplication occurred in all cheeses (mean count, 3.7 log CFU/g). Motile aeromonads were detected in raw ewe's milk, curd, and cheese. Identification to species' level of 38 isolates which shared the properties of A. hydrophila and A. caviae was based on the "suicide phenomenon" (22 strains were identified as A. hydrophila and 16 as A. caviae ). All strains of A. caviae were β-hemolytic, showed suicidal activity, and failed to produce caseinase.