Abstract
The significance of Escherichia coli-induced mastitis in cows, associated with the presence of virulence genes and wide range resistance to 20 antimicrobials, is concluded. The targeted surveillance included 67 randomly chosen cows on 10 rural farms, distributed among four out of the five provinces of Lebanon. There was a high frequency of California Mastitis Test (CMT)positive milk samples in the targeted cows, equivalent to 77.6%, with recovered E. coli from 31% of the CMT-positive samples. A significant correlation existed between the E. coli count (Y) and the CMT score (X) in a regression equation of Y=0.6691X-0.2454 (P < 0.05). The respective frequencies of three genes, in randomly chosen 75 biochemically confirmed E. coli isolates, recovered from CMT-positive milk samples, were: eae gene (8.0%), F5 gene of K99-E. coli (1.3%), and rfbE of O157 serotype of E. coli (0%). The nucleotide sequence of the F5 gene of K99-E. coli recovered from one cow revealed a 4% difference from that of the E. coli vaccine strain used on that herd. The range of percent resistance of the 75 E. coli isolates to 20 antimicrobials was 1-100%. The presence of an average resistance to 20 drugs of 37.9% in Intimin (author, please check spelling) (eae) positive-E. coli is of high significance in chemotherapeutic programs applied on E. coli-induced mastitis in cows.