MILK AS A POTENTIAL SOURCE OF AEROMONAS GASTROINTESTINAL INFECTION

The incidence and properties of Aeromonas species found in milk were e xamined to evaluate the potential of milk as a vehicle for the transmi ssion of Aeromonas gastroenteritis. Aeromonads are common in raw milk (60%, 43 of 72 samples, positive). Pasteurization is effective at remo ving this contamination. Nevertheless, around 4% (seven of 183) pasteu rized milk samples contained potentially significant strains, apparent ly introduced by subsequent handling of the milk. Some of these strain s were indistinguishable froin diarrhea-associated strains and were ab le to produce exotoxins at 37-degrees-C and adhere to epithelial cells . Adhesive ability and piliation increased when these strains were gro wn at low temperature. Such strains, although mesophilic, could reach high numbers in refrigerated milk without detectable spoilage of the m ilk. They pose the risk of colonization and in vivo toxin production. Further studies are required, but ingestion of preformed toxins produc ed in stored pasteurized milk may be of less concern, as psychrotrophi c aeromonads, with the ability to produce large amounts of exotoxins i n milk, appear to be uncommon and exotoxin production in milk was sign ificantly lower than in bacteriological medium.