Longitudinal Study of Shiga Toxin-Producing Escherichia coli Shedding in Sheep Feces: Persistence of Specific Clones in Sheep Flocks

Abstract

To provide information on the persistence and maintenance of colonization with Shiga toxin-producing Escherichia coli (STEC) in sheep, pulsed-field gel electrophoresis analysis of STEC isolates (n ‫؍‬ 145) belonging to serogroups O5, O91, and O146 from 39 healthy animals was performed in a 12-month longitudinal study carried out with four sheep flocks. At the flock level as well as the individual-animal level, the same clones were obtained on sampling occasions separated by as much as 11 months.Shiga toxin-producing Escherichia coli (STEC) strains have recently emerged as important food-borne pathogens. Human diseases ranging from mild diarrhea to hemorrhagic colitis and hemolytic-uremic syndrome, typically affecting children, the elderly, and immunocompromised patients, can be caused by STEC (6). Serogroup O157 especially represents a major public health concern worldwide. However, as non-O157 STEC strains are more prevalent than O157 strains in meat-producing animals and as contaminants in foods, humans are more likely to become exposed to such strains (3, 9, 23), and therefore, non-O157 STEC should not be overlooked in human disease investigations. Although healthy asymptomatic cattle are the best-recognized animal reservoir for STEC strains (5), sheep are an important source of these organisms for humans in some countries (2,4,8,19). The ecology and epidemiology of STEC O157 in cattle appear to be very complex, often involving multiple clones on a single farm (14, 17). There is some previously published information about the on-farm persistence of specific clones in different cattle production systems (13,15,18,21), including information about persistence in individual animals in a few cases. Nevertheless, apart from the findings of a study of STEC O157 (12), little is known about the natural colonization of sheep with STEC over long time periods and the ecology of STEC strains in sheep flocks. A longitudinal study was conducted to provide information on the persistence and maintenance of colonization with non-* Corresponding author. Mailing address: Patología Infecciosa y Epidemiología,

Zoonotic Agents in Small Ruminants Kept on City Farms in Southern Germany

“…The serotypes that have been most frequently reported to have been found in sheep are O5, O91, O117, O128, and O146. Several serotypes found in sheep, such as O5, O26, O91, O128/O128:H2, and O146:H8, have also been isolated from humans in clinical cases (2,3,4,13,29,47,48,50,51). Our findings in sheep also differ from those in previous studies, but the one similarity we detected, represented by O91:H14, is closely related to serotypes that were reported in cases of human disease.…”

Genotypic and Phenotypic Characterization of Antimicrobial-Resistant Escherichia coli from Farm-Raised Diarrheic Sika Deer in Northeastern China

“…This indicated that farm-raised sika deer has become natural reservoir for pathogenic E. coli O157 in Northeastern China. The dominant serogroups of the E. coli isolates in this study were markedly different from those of diarrheic sheep flocks (O5, O6, O76, O87, O91, O123, O128, O146, O166 and O176) and cattle calves (O56, O78, O8 and O164) [3], [16]. The observed difference in serogroups among farm-raised sika deer, livestock and wild animals might be ascribed to their different feeding managements, habitats and antimicrobials ingests.…”

“…Recently, increasing interest has been given to antimicrobial-resistant pathogenic bacteria from various domestic animals and their habitats. Antimicrobial-resistant bacteria have been detected in a variety of domestic animals and the environments that are affected by stockbreeding [2], [3]. E. coli , a type of bacteria common in the intestine of warm-blooded animals, was widely used as an indicator of fecal contamination in drinking water system assessment and food safety evaluation [4].…”

Genetic diversity and antibiotic resistance inShigella dysenteriaeandShigella boydiistrains isolated from children aged <5 years in Egypt

“…Little information on the integron content of S. boydii and S. dysenteriae isolates is available, but in our study, harbouring a class 1 integron among either Shigella spp. and is considered a molecular typing tool with high discriminatory power for detection of outbreaks [24,35] and longitudinal observation of bacterial populations [36,37]. Class II integrons (intI2) were detected in only 24 % of S. dysenteriae and 33 % of S. boydii AM-resistant isolates.…”