Factors Affecting Virulence of <i>E. coli</i> Isolates from Diarrheic Sheep and Goats

Abstract

This study was carried out to investigate factors affecting virulence of E. coli in sheep and goats; parameters measured were, incidence of E. coli, effect of age, haemolytic activity serotyping of the pathogenic E. coli, detection of enterotoxin, astA and verotoxin genes of E. coli isolates using Polymerase chain reaction And antibiogram to the E. coli isolates. E. coli was isolated at highest percentage from diarrheic sheep at age ranged from 1 to 6 month, highest percentage from diarrheic goats aged from 7 to 12 month. E. coli isolated from diarrheic sheep gave alpha, beta and gamma hemolysis at percentage of 66.7 %, 18.2 % and 15.1%, respectively. Moreover, E. coli isolated from diarrheic goats gave alpha, beta and gamma hemolysis at percentage of 55%, 30% and 15 %, respectively. The results revealed that serotype O26 was the most E. coli serotype (31.4% ) that gave a positive Congo red followed by E. coli serotype O78 (22.9%) and E. coli serotype O86 (17.1%). Results of detection of verotoxin 2 gene of E. coli isolated from diarrheic sheep and goats revealed that the gene could not be detected in all examined E. coli isolates (7 isolates). On the other hand, results of detection STa gene in E. coli isolated from diarrheic sheep and goats revealed that 5 out of 7 E. coli isolates (71.4 %) were detected. astA gene of E. coli isolated from diarrhoeic sheep and goats was detected in all the examined isolates (7 isolates). It could be concluded that E. coli isolated from diarrhoeic sheep and goats was pathogenic and producer for enterotoxin and astA. Moreover, PCR is a simple and rapid method for detection of STa , astA and VT2 genes of E. coli

Keywords: E. coli isolates; virulence; sheep; goats; PCR