ESCHERICHIA-COLI STRAINS PRODUCING HEAT-STABLE ENTEROTOXIN (ST) AND VEROTOXIN (VT) ISOLATED FROM DIARRHEIC CALVES AND LAMBS

Due to its importance in bovine and ovine neonatal mortality, the presence of E. coli strains that produce heat-stable enterotoxin (ST) and verotoxin (VT) was studied in faeces on neonate calves and lambs. Fourty seven and thirty one faeces samples were collected from calves and lambs with diarrhoea, respectively. Samples were cultivated in both eosin-metilen blue and ovine blood agar in order to study the characteristics of the colonies and to biochemically identify the isolated strains, The production of ST toxin was tested by the infant mouse technique. Detection of VT was performed by the micromethod of Vero cell culture. Three (6.4%) positive and 8 (17%) suspicious strains to ST as well as 1 (2.1%) positive strain to VT were isolated from calves. On the other hand, in neonate lambs 2 (6.5%) strains were doubtful to ST and 2 (6.5%) were VT producer strains. Their possible role in the pathogenesis of the diarrhea is discussed. The possibility that both animal species could be infection sources to man is also considered.