A contribution on Coliforms causing mastitis in cows with reference to serotypes and virulence factors of E. coli isolates

الملخص EN

Escherlchia coil (E.

colt) is the predominant coliform species causing intramammary infections.

Where in the present study, E.

coil isolates were 18 strains (17.82 %) followed by Enterobacter aerogenes 3 strains (2.97 %) and Klebslella pneuntoniae one strain (0.99 %) from 101 clinical mastitic milk samples of cows.

Eighteen E.

coil isolates were serotyped to nine different serogroups ; 0111 : H4 (3), 0127 : 116 (3), 026 (2), 0126 (2), 0119 : 116 (1), 0114 : H21 (1), 055 : H7 (1), 044 : H18 (1), 0124 (1) and (3) untyped.

Virulence tests were performed on the 18 isolated E.

coil, it was found that 15 isolates (83.3 %) were serum resistant, 13 isolates (72.2 %) had Congo Red binding activity, 6 isolates (33.3 %) were invasive and one isolate (5.6 %) had haemolytic activity.

PCR was applied to detect the presence of Shiga like toxin producing E.

coil (stxl and stx2 genes) on the nine different strains (one strain for each serogroup), where sal and stx2 were found in 8 (88.9 %) and 4 (44.4 %) of the nine examined strains, respectively.

While sal and stx2 genes were found together in 3 strains (33.3 %).

Conclusions: E.

coil isolates usually posses one or more virulence factors that may help in establishment at the infection site and subsequently causing clinical bovine mastitis.