Prevalence and genetic profiles of Shiga toxin-producing Escherichia coli strains isolated from buffaloes, cattle, and goats in central Vietnam

Vu-Khac, Hung; Cornick, Nancy A.

doi:10.1016/j.vetmic.2007.07.023

Cited by 73 publications

(71 citation statements)

References 36 publications

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“…Lesser developed countries have also reported the presence of STEC in their small ruminant population. In Vietnam, 100% of the goat farms surveyed had animals shedding STEC, and the within-herd shedding was dramatically higher than that reported elsewhere, with up to 65% of animals shedding STEC (53). In Bangladesh, almost 10% of the small ruminants being slaughtered tested positive for STEC O157 (54).…”

Section: Small Ruminantsmentioning

confidence: 80%

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Animal Reservoirs of Shiga Toxin-ProducingEscherichia coli

2014

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Shiga toxin-producing Escherichia coli (STEC) strains have been detected in a wide diversity of mammals, birds, fish, and several insects. Carriage by most animals is asymptomatic, thus allowing for dissemination of the bacterium in the environment without detection. Replication of the organism may occur in the gastrointestinal tract of some animals, notably ruminants. Carriage may also be passive or transient, without significant amplification of bacterial numbers while in the animal host. Animals may be classified as reservoir species, spillover hosts, or dead-end hosts. This classification is based on the animal's ability to (i) transmit STEC to other animal species and (ii) maintain STEC infection in the absence of continuous exposure. Animal reservoirs are able to maintain STEC infections in the absence of continuous STEC exposure and transmit infection to other species. Spillover hosts, although capable of transmitting STEC to other animals, are unable to maintain infection in the absence of repeated exposure. The large diversity of reservoir and spillover host species and the survival of the organism in environmental niches result in complex pathways of transmission that are difficult to interrupt.

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Section: Small Ruminantsmentioning

confidence: 80%

“…In Vietnam, 27% of the buffaloes screened were found to be positive for STEC. Serotyping of the isolates, however, revealed that none of the isolates were O157 (53).…”

Section: Other Ruminants Water Buffalo (Bubalus Bubalis)mentioning

confidence: 94%

Animal Reservoirs of Shiga Toxin-ProducingEscherichia coli

2014

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“…STEC strains possessing stx 1 are more frequently isolated from suckling calves, while stx 2 -possessing strains dominate in weaned calves and adult cattle (12,55). Subtypes stx 2 and stx 2c are found in STEC isolates from calves more often than stx 2d is found (55,62), whereas detection of stx 2e (43), stx 2-NV206 (4), and stx 2g (30,62) is rare.…”

Section: Discussionmentioning

confidence: 99%

Maternally and Naturally Acquired Antibodies to Shiga Toxins in a Cohort of Calves Shedding Shiga-Toxigenic Escherichia coli

Fröhlich

Baljer

Menge

2009

Appl Environ Microbiol

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Calves become infected with Shiga toxin-producing Escherichia coli (STEC) early in life, which frequently results in long-term shedding of the zoonotic pathogen. Little is known about the animals' immunological status at the time of infection. We assessed the quantity and dynamics of maternal and acquired antibodies to Shiga toxins (Stx1 and Stx2), the principal STEC virulence factors, in a cohort of 27 calves. Fecal and serum samples were taken repeatedly from birth until the 24th week of age. Sera, milk, and colostrums of dams were also assessed. STEC shedding was confirmed by detection of stx in fecal cultures. Stx1-and Stx2-specific antibodies were quantified by Vero cell neutralization assay and further analyzed by immunoblotting. By the eighth week of age, 13 and 15 calves had at least one stx 1 -type and at least one stx 2 -type positive culture, respectively. Eleven calves had first positive cultures only past that age. Sera and colostrums of all dams and postcolostral sera of all newborn calves contained Stx1-specific antibodies. Calf serum titers decreased rapidly within the first 6 weeks of age. Only five calves showed Stx1-specific seroconversion. Maternal and acquired Stx1-specific antibodies were mainly directed against the StxA1 subunit. Sparse Stx2-specific titers were detectable in sera and colostrums of three dams and in postcolostral sera of their calves. None of the calves developed Stx2-specific seroconversion. The results indicate that under natural conditions of exposure, first STEC infections frequently coincide with an absence of maternal and acquired Stx-specific antibodies in the animals' sera.

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“…In humans, epidemiologic data suggest that E. coli O157 strains that express stx2 are more important than stx1 in the development of HUS, and that strains that express stx2 alone are more likely to be associated with the progression to HUS than strains that produce both stx1 and stx2 (Griffin, 1995) In this study, the presence of STEC harboring the genes stx1 and stx2 in raw milk sample was detected. STEC harboring stx1 and stx2 genes were reported to be typical cattle colonizers (Brett et al, 2003;Vu-Khac & Cornick, 2008). Some authors have recently investigated 593 foodborne STEC strains for their serotypes and for nine virulence genes (stx1, stx1c, stx1d, stx2, stx2b, stx2e, stx2g, E-hlyand eae), and they observed a significant association of stx1and stx2 genes with bovine meat and milk products.…”

Section: Preparation Of Template Dnamentioning

confidence: 99%