Abstract
Diarrhea caused by Escherichia coli in calves is an important problem in terms of survivability, productivity and treatment costs. In this study, 88 of 150 diarrheic animals tested positive for E. coli. Of these, 54 samples had mixed infection with other bacterial and/or parasitic agents. There are several diarrheagenic E. coli pathotypes including enteropathogenic E. coli (EPEC), Shiga-toxin producing E. coli (STEC), enterotoxigenic E. coli (ETEC) and necrotoxigenic E. coli (NTEC). Molecular detection of virulence factors Stx2, Cdt3, Eae, CNF2, F5, Hly, Stx1, and ST revealed their presence at 39.7, 27.2, 19.3, 15.9, 13.6, 9.0, 3.4, and 3.4 percent, respectively. As many as 13.6% of the isolates lacked virulence genes and none of the isolate had LT or CNF1 toxin gene. The odds of isolating ETEC from male calves was 3.6 times (95% CI: 1.1, 12.4; P value = 0.042) that of female calves, whereas the odds of isolating NTEC from male calves was 72.9% lower (95% CI: 91.3% lower, 15.7% lower; P value = 0.024) than that in females. The odds of isolating STEC in winter was 3.3 times (95% CI: 1.1, 10.3; P value = 0.037) that of spring. Antibiograms showed 48 (54.5%) of the isolates to be multi-drug resistant. The percent resistance to tetracycline, streptomycin, ampicillin, and trimethoprim-sulfamethoxazole was 79.5, 67.0, 54.5, and 43.0, respectively. Ceftazidime (14.8%), amoxicillin-clavulanic acid (13.6%) and aztreonam (11.3%) showed the lowest resistance, and none of the isolates was resistant to imipenem. The results of this study can help improve our understanding of the epidemiological aspects of E. coli infection and to devise strategies for protection against it. The prevalence of E. coli pathotypes can help potential buyers of calves to avoid infected premises. The antibiograms in this study emphasizes the risks associated with the random use of antibiotics.
Highlights
Cattle and water buffaloes (Bubalus bubalis) are a crucial source of red meat, milk, and milk products in most of the developing countries including Egypt [1]
enteropathogenic E. coli (EPEC) was detected in 4.5% samples; the Eae gene was present in 17 (19.3%) isolates
E. coli is a major cause of neonatal diarrhea in both cattle and water buffaloes [25]
Summary
Cattle and water buffaloes (Bubalus bubalis) are a crucial source of red meat, milk, and milk products in most of the developing countries including Egypt [1]. The newborn calves of these species have poor immune system, which makes them susceptible to viral and bacterial infections. Diarrhea caused by Escherichia coli in newborn calves is one of the most economically important problems. There are several diarrheagenic E. coli pathotypes including enteropathogenic E. coli (EPEC), Shiga-toxin producing E. coli (STEC), enterotoxigenic E. coli (ETEC) and enterohaemorrhagic E. coli (EHEC) [2, 3]. The most predominant pathotype in developed countries is ETEC [4], which has two groups of virulence factors e.g., enterotoxins and colonization factors (mainly fimbriae). Many types of fimbriae have been identified but the most common in calves are F5 and F4 [6]
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