Isolation And Molecular Characterization Of Shiga Toxin Producing Escherichia coli In Cattle, Water And Diarrhoeal Children From The Pastoral Systems Of Southwestern Uganda (original) (raw)
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Journal of Animal Science and Veterinary Medicine, 2016
The study was designed to review the incidences and characteristics of Shiga toxin-producing Escherichia coli (STEC) from farm animals and humans in tropical Africa. Serotypes O157, O26, O103, O91, O45 and O111 are usually associated with public health risks, and these serotypes are most frequently isolated from food animals. The main virulent factors of STEC associated with human diseases are potent cytotoxins (shiga toxins [stx] stx1 and stx2), which are encoded by the stx1 and stx2 genes. Two additional markers also play a role in the pathogenesis of Hemorrhagic colitis (HC) and Hemolytic Uremic Syndrome (HUS): an outer membrane protein (intimin), encoded by the eae gene, and enterohaemolysin, encoded by the ehlyA gene. All age groups of animals and humans can be infected with STEC, but young animals and children, the elderly, and those with compromised immune systems are the most severely affected. Little is known about factors that determine susceptibility to STEC infection and...
Scientific Reports, 2016
This study assessed the prevalence and zoonotic potential of Shiga toxin-producing Escherichia coli (STEC) sampled from 104 dairy units in the central region of Zambia and compared these with isolates from patients presenting with diarrhoea in the same region. A subset of 297 E. coli strains were sequenced allowing in silico analyses of phylo-and sero-groups. The majority of the bovine strains clustered in the B1 'commensal' phylogroup (67%) and included a diverse array of serogroups. 11% (41/371) of the isolates from Zambian dairy cattle contained Shiga toxin genes (stx) while none (0/73) of the human isolates were positive. While the toxicity of a subset of these isolates was demonstrated, none of the randomly selected STEC belonged to key serogroups associated with human disease and none encoded a type 3 secretion system synonymous with typical enterohaemorrhagic strains. Positive selection for E. coli O157:H7 across the farms identified only one positive isolate again indicating this serotype is rare in these animals. In summary, while Stx-encoding E. coli strains are common in this dairy population, the majority of these strains are unlikely to cause disease in humans. However, the threat remains of the emergence of strains virulent to humans from this reservoir.
Scientific Reports
In this study, 140 cattle STEC isolates belonging to serogroups O157, O26, O145, O121, O103 and O45 were characterized for 38 virulence-associated genes, antimicrobial resistance profiles and genotyped by PFGE. The majority of isolates carried both stx1 and stx2 concurrently, stx2c, and stx2d; plasmidencoded genes ehxA, espP, subA and saa but lacked katP and etpD and eaeA. Possession of eaeA was significantly associated with the presence of nle genes, katP, etpD, ureC and terC. However, saa and subA, stx1c and stx1d were only detected in eaeA negative isolates. A complete OI-122 and most non-LEE effector genes were detected in only two eaeA positive serotypes, including STEC O157:H7 and O103:H2. The eaeA gene was detected in STEC serotypes that are commonly implicated in severe humans disease and outbreaks including STEC O157:H7, STEC O145:H28 and O103:H2. PFGE revealed that the isolates were highly diverse with very low rates of antimicrobial resistance. In conclusion, only a small number of cattle STEC serotypes that possessed eaeA, had the highest number of virulenceassociated genes, indicative of their high virulence. Further characterization of STEC O157:H7, STEC O145:H28 and O103:H2 using whole genome sequencing will be needed to fully understand their virulence potential for humans. Shiga toxin-producing Escherichia coli (STEC) are zoonotic food-borne pathogens characterized by mild to severe diarrhea, hemorrhagic colitis (HC) and the hemolytic uremic syndrome (HUS), a leading cause of acute renal failure in young children and the elderly 1. Cattle are the major reservoir of STEC, and humans acquire STEC infections through ingestion of contaminated food of cattle origin 2. STEC serogroups O26, O45, O103, O111, O121, O145, and O157 are frequently associated with severe illness and outbreaks in humans 3 , and colloquially termed the "top or big 7". The ability of STEC to cause disease in humans depends on a number of virulence factors. Bacteriophage-encoded Shiga toxins (Stx1 and Stx2) are the main STEC virulence factors 4. Furthermore, a number of stx1 and stx2 Shiga toxin subtypes (15) have been described, including four stx1 subtypes, (stx1a, stx1c and stx1d, stx1e) and at least 11 stx2 subtypes have been identified:
Tropical Animal Health and Production, 2018
Prevalence and distribution of Shiga toxin-producing Escherichia coli (STEC) serogroups from the faecal samples of cattle and camels slaughter in Maiduguri abattoir and their antibiotic resistance profile of the isolates were determined. The highest prevalence (24%) was recorded in the month of September and more STEC isolates came from cattle than the camels. There was significant (P < 0.05) seasonal trend in the prevalence of STEC among cattle and camel with more cases recorded during the wet season. Although, the study did not demonstrate significant influence of sex from the various sources. The serogroups recorded in this study were O157, O26, O91, O103 and O111. There was no significant difference (P < 0.05) between the detection rates of serogroups. The serogroup O26 was significantly (P < 0.05) the most observed serogroup in both camels and cattle. None of the STEC isolates tested positive for the O45 serogroup. PCR assays shows that 50 (63.3%) of the 86 STEC isolates carried the stx2 gene, 34 (43%) possessed the stx1 gene, and 14 (16.3%) carried both stx1 and stx2 genes. Other genes detected include eae and ehlyA. The antimicrobial resistance among the STEC O157 and non-O157 isolates from cattle and camels in Maiduguri abattoir were very high and the STEC isolates were resistant to at least one or more of the antimicrobial agents tested. There was also multidrug resistance with the most frequent occurring patterns been ampicillin/nalidixic acid and tetracycline/trimethoprim. However, all the 79 isolates were sensitive to chloramphenicol, ceftazidime and ceftriaxone; therefore, these drugs could be drugs of choice in the treatment of STEC infections.
Characterization of Shiga toxin-producing Escherichia coli isolated from cattle and their contacts
Mansoura Veterinary Medical Journal
To estimate the occurrence of Shiga toxin-producing E. coli (STEC) in cattle reared on farms versus those belonged to smallholders as well as their contact keepers. Design: Descriptive study. Samples: The study comprised 260 samples consisting of f ninety each of (n = 90) for each of cattle feces and milk samples that were originated either from smallholding cattle (n=30) or from farm cattle (n=60) alongside eighty stool specimens were collected from smallholders contacts (n=50) and farm workers (n=30). Procedures: All samples were examined using conventional bacteriological and molecular techniques. Results: The overall occurrence of E. coli in animal samples was 25/180 with a percentage of 13.9. In cattle feces, it was 14.4% (13/90), whereas it was 13.3% (12/90) in milk samples. In human stool samples, E. coli i isolates were also identified in smallholders' contacts (14%, 7/50) and farm workers (16.7%, 5/30). The most prevalent serotypes obtained from farm cattle and their keepers were (O157 and O55) and from smallholders' cattle and their contact were (O111, O157, and O11). The PCR analysis showed that stx2 was the most predominant genotypes followed by stx1. The recovered E. coli isolates showed high resistance to penicillin G (97.3%) and 81% (30/37) of the tested strains exhibited multidrug resistance. Conclusion and clinical relevance: the presence of Shiga toxigenic and multiple drug-resistant strains of E. coli in the study area poses a high potential risk. Hence, strict hygienic measures should be followed to reduce the risk of STEC occurrence in smallholding cattle and those in commercial farms.
Comparative Immunology, Microbiology and Infectious Diseases, 2015
In the present study the occurrence, genotypic characteristics and relatedness of Shiga toxin-producing Escherichia coli (STEC) isolated from 235 fecal samples of diarrheic children (n = 75), sheep (n = 80), and cattle (n = 80) were investigated. Overall, STEC was found in 4%, 61.2%, and 18.7% of diarrheic children, sheep and cattle, respectively. Three of the four STEC isolates from diarrheic children yielded the stx1/ehly profile. The predominant virulence profile of sheep isolates was stx1/ehly (85.2%), but cattle isolates were heterogeneous. Genetic relatedness and diversity of 36 selected isolates were analyzed by enterobacterial repetitive consensus sequences fingerprinting (ERIC) and phylogrouping. In total, 19 ERICtypes were observed in humans (n = 2), sheep (n = 5), and cattle (n = 12) isolates. The majority of the sheep STEC were assigned into B1 phylogroup (83.3%), but cattle isolates belonged to different phylogroups with B1 predominance. Three human STEC isolates had the major characteristics of sheep isolates but revealed distinct fingerprint. These findings indicate that cattle can potentially carry a diverse group of STEC strains.
BMC veterinary research, 2018
All over the world, Shiga toxin-producing Escherichia coli (STEC) are considered as important zoonotic pathogens. Eight serogroups have the greatest role in the outbreaks and diseases caused by STEC which include O26, O45, O103, O111, O113, O121, O145 and O157. Ruminants, especially cattle are the main reservoirs but the role of small ruminants in the epidemiology of human infections has not been thoroughly assessed in many countries. The objective of this research was to investigate the pathogenic potential of the STEC strains isolated from slaughtered goats. In this study, a total of 57 STEC strains were recovered from 450 goats and characterized by subtyping of stx genes, O-serogrouping, phylo-typing and DNA fingerprinting. Amongst 57 STEC strains isolated from goats, the prevalence of stx1 was significantly more than stx2 (98.2% vs. 24.5%; P ≤ 0.05), and 22.8% of strains harbored both stx1 and stx2 genes. Three (5.2%) isolates were characterized as EHEC, which carried both eae a...
Letters in Applied Microbiology, 2007
Aims: To determine the prevalence of Shiga toxin-producing Escherichia coli (STEC) and serotypes and virulence markers of the STEC isolates from beef and dairy cattle in Rio Grande do Sul, Brazil. Methods and Results: Faecal samples from beef cattle were collected at slaughterhouses. The isolates were submitted to colony hybridization assay with specific DNA probes for stx1, stx2 and eae genes, and serotyped for the identification of O and H antigens. Thirty-nine per cent of beef cattle surveyed harboured at least one STEC strain. Among the distinct serotypes identified, 10 were shared by both beef and dairy cattle. Most of the strains isolated harboured stx2. Genotypic and phenotypic profiles allowed the identification of 34 and 31 STEC strains, isolated from beef and dairy cattle,
Toxins
Shiga-toxin-producing Escherichia coli is a foodborne pathogen commonly associated with human disease characterized by mild or bloody diarrhea hemorrhagic colitis and hemolytic uremic syndrome. This study investigated the occurrence of STEC in fecal samples of 289 goats in South Africa using microbiological culture and PCR. Furthermore, 628 goat STEC isolates were characterized by serotype (O:H) and major virulence factors by PCR. STEC was found in 80.2% (232/289) of goat fecal samples. Serotyping of 628 STEC isolates revealed 63 distinct serotypes including four of the major top seven STEC serogroups which were detected in 12.1% (35/289) of goats: O157:H7, 2.7% (8/289); O157:H8, 0.3%, (1/289); O157:H29, 0.3% (1/289); O103:H8, 7.6% (22/289); O103:H56, 0.3% (1/289); O26:H2, 0.3% (1/289); O111:H8, 0.3% (1/289) and 59 non-O157 STEC serotypes. Twenty-four of the sixty-three serotypes were previously associated with human disease. Virulence genes were distributed as follows: stx1, 60.6% ...