Camel - calves diarrhoea instigated by Escherichia coli and detection of some virulence - associated markers

ABSTRACT

Bacteriological examination of internal organ specimens including intestine, liver, spleen, lungs and kidneys [45] and faecal samples [77] from necropsied and diarrhoeic camel-calves respectively that had severe episodes of diarrhoea, revealed the isolation of Escherichia coli from 33/ 45 [73.3%] of the necropsied specimens and 58/ 77 [75.3%] of the faecal samples. Eleven sero-groups were detected, with high prevalence of O3 [19.8%], OM [17.6%] O80 [16.5%]. Two enterohaemorrhagic, enterotoxigenic O157 isolates [2.2%] were also detected one from each group of specimens. E. coli isolation from faecal specimens revealed wider serogroups range as O91, O125 and O29 were additionally detected from faecal samples and not from the organ specimens. Investigating of some virulence markers of the isolates revealed that the haemolytic activity was expressed significantly higher [p < 0.01] than the rest of investigated markers as 43/91 [47.3%] were haemolysin producers. The detection of the VT2 gene was revealed in 34/91, [37.4%], Shiga-like toxin production in 26/91, [28.6%] and Congo red binding affinity was expressed in 31/91 [34.1%] of the isolates. The highest percentage of hydrophobic activity was [81.2 +/- 5.7] by the O163 isolates, whereas the lowest activity [40.2 +/- 3.2] was recorded by the O125 isolates. It was observed that the highest expression of virulence markers was among the isolates of O157 [2 isolates], O26 [3 isolates] and O163 [2 isolates], as these isolates expressed full range of the investigated virulence markers. The rest of E. coli isolates from other serogroups revealed abridged virulence criteria. Antibiotic sensitivity testing of E coli revealed highest sensitivity against gentamicin [94.4%], trimethoprim sulphamethazole [91.2%], streptomycin [87.9%] and cephalosporine [84.6%], It was concluded that highly virulent E. coli strains induced infection in camel-calves, and their treatment with the recommended antibiotics could curb the episode of the diarrhoea in few days