Molecular screening and risk factors of enterotoxigenic Escherichia coli and Salmonella spp. in diarrheic neonatal calves in Egypt

Abstract

The aim of the present study was to carry out molecular epidemiological investigation on enterotoxigenic Escherichia coli (ETEC) K99 and Salmonella spp. in diarrheic neonatal calves. Fecal samples were obtained from 220 diarrheic calves at 9 farms related to four governorates in central and northern Egypt. E. coli and Salmonella spp. isolates were examined for E. coli K99 and Salmonella spp. using PCR. ETEC K99 was recovered from 20 (10.36 %) out of 193 isolates, whereas Salmonella spp. was recovered from nine calves (4.09%). Multivariable logistic regression was used to evaluate the risk factors associated with both infections. ETEC K99 was significantly affected by age (P<0.01; OR: 1.812; CI 95%: 0.566-1.769), colostrum feeding practice (P<0.01; OR: 5.525; CI 95%: 2.025-15.076), rotavirus infection (P<0.001; OR: 2.220; CI 95%: 0.273-1.251), vaccination of pregnant dams with combined vaccine against rotavirus, coronavirus and E. coli (K99) (P<0.001; OR: 4.753; CI 95%: 2.124-10.641), and vitamin E and selenium administration to the pregnant dam (P<0.01; OR: 3.933; CI 95%: 0.703-1.248). Infection with Salmonella spp. was found to be significantly affected by the animal age (P<0.05; OR: 0.376; CI 95%: 0.511-1.369), Hygiene (P<0.05; OR: 0.628; CI 95%: 1.729-5.612), and region (P<0. 01; OR: 0.970; CI 95%: 0.841-1.624). The results of the present study indicate the importance of PCR as rapid, effective and reliable tool for screening of ETEC and Salmonella spp. when confronted with cases of undifferentiated calf diarrhea. Moreover, identification of the risk factors associated with the spreading of bacteria causing diarrhea may be helpful for construction of suitable methods for prevention and control.

Virulence factors inEscherichia coliisolated from calves with diarrhea in Vietnam

“…In the present study, 53 of 345 isolates carried the f5 (36 isolates) and f41 (17 isolates) genes, and all of the F5-positive strains isolated from diarrheic calves were less than 7-day old. The susceptibility of the calves to ETEC in this age period is in agreement with previous reports [21,38]. Interestingly, in this study, we found that none of the F5-positive strains encoded enterotoxin genes (STa) when analyzed by PCR and they were also negative when tested with baby mice (data not show).…”

Characterization of Escherichia coli virulence genes, pathotypes and antibiotic resistance properties in diarrheic calves in Iran

“…Totally, the prevalence of E. coli strains isolated from calves with diarrhea in Iran (76.45%, our results) was significantly higher than Egypt (10.36%) [37] and India (42.65%). Mora et al [38] reported that 12% of the calves and 22% of the farms samples were positive for highly virulent STEC serotype O157:H7.…”

Molecular screening of pathogenic Escherichia coli strains isolated from dairy neonatal calves in Cordoba province, Argentina

“…Pathogenic E. coli strains have different virulence factors that allow them to colonize the host's small intestine, avoiding the immune response and stimulating the deleterious inflammatory response to produce diarrhea 11,45 . These virulence factors include the antigens of colonization or adhesion (F2---F6, F17, F18, F41 fimbriae and intimin) and exotoxins (heat-labile enterotoxin [LT], heat-stable enterotoxins [STa and STb] and verotoxins [VT]) 26 .…”

“…Farm animal and human diarrhea are frequently due to infection by one or several of E. coli pathotypes: enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroinvasive E. coli (EIEC), Vero toxin-producing/Shiga toxin-producing E. coli (VTEC/STEC) which include its well-known subgroup enterohemorrhagic E. coli (EHEC), enteroaggregative E. coli (EAggEC) and enteroadherent E. coli (EAdEC) 28 . ETEC infection is the most common type of colibacillosis in young animals especially in calves and piglets 45 .…”