Shiga Toxin–Producing Escherichia coli Contamination of Raw Beef and Beef-Based Ready-to-Eat Products at Retail Outlets in Pretoria, South Africa

Onyeka, Libby O.; Adesiyun, Abiodun A.; Keddy, Karen H.; Madoroba, Evelyn; Manqele, Ayanda; Thompson, Peter N.

doi:10.4315/0362-028x.jfp-19-372

Cited by 19 publications

(16 citation statements)

References 43 publications

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“…Escherichia coli O150:H2 is not often found as contaminating agent in foods and environments, although it has been described as an emerging serogroup for over several years (Monaghan et al, 2012;Onyeka et al, 2020). The group of 21 closely resembling STECs from our study showed closest relationship with strains belonging to phylogroup B1, the group to which E. coli O104:H4 strains belong to.…”

Section: Discussionsupporting

confidence: 48%

Circulation of Shiga Toxin-Producing Escherichia coli Phylogenetic Group B1 Strains Between Calve Stable Manure and Pasture Land With Grazing Heifers

et al. 2020

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Escherichia coli strains carrying Shiga toxins 1 and 2 (stx 1 and stx 2), intimin (eae), and hemolysin (ehxA) production genes were found in grass shoot, rhizosphere soil, and stable manure samples from a small-scale cattle farm located at the center of Netherlands, using cultivation-dependent and-independent microbiological detection techniques. Pasture land with grazing heifers in the first year of sampling in 2014 and without grazing cattle in 2015 was physically separated from the stable that housed rose calves during both years. Manure from the stable was applied to pasture via injection into soil once per year in early spring. Among a variety of 35 phylogenetic distinctly related E. coli strains, one large group consisting of 21 closely resembling E. coli O150:H2 (18), O98:H21 (2), and O84:H2 (1) strains, all belonging to phylogenetic group B1 and carrying all screened virulence traits, was found present on grass shoots (10), rhizosphere soil (3), and stable manure (8) in 2014, but not anymore in 2015 when grazing heifers were absent. Presence and absence of these strains, obtained via enrichments, were confirmed via molecular detection using PCR-NALFIA in all ecosystems in both years. We propose that this group of Shiga toxin-producing E. coli phylogenetic group B1 strains was originally introduced via stable manure injection into the pasture. Upon grazing, these potential pathogens proliferated in the intestinal track systems of the heifers resulting in defecation with higher loads of the STEC strain onto the grass cover. The STEC strain was further smeared over the field via the hooves of the heifers resulting in augmentation of the potential pathogen in the pasture in 2014, whereas in 2015, in the absence of heifers, no augmentation occurred and only a more diverse group of potentially mild virulent E. coli phylogenetic group A and B1 strains, indigenous to pasture plants, remained present. Via this model, it was postulated that human pathogens can circulate between plants and farm animals, using the plant as an alternative ecosystem. These data indicate that grazed pasture must be considered as a potential carrier of human pathogenic E. coli strains and possibly also of other pathogens.

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Section: Discussionsupporting

confidence: 48%

Circulation of Shiga Toxin-Producing Escherichia coli Phylogenetic Group B1 Strains Between Calve Stable Manure and Pasture Land With Grazing Heifers

et al. 2020

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“…Reducing foodborne pathogens (from any source) promotes food chain integrity, with Escherichia and Clostridioides reported as being amongst the most concerning from a One Health perspective [ 82 , 88 ]. Additionally, as these species are potentially toxicogenic, synthesised toxins may travel to distal sites of the host organism and remain in meat products postprocessing [ 5 , 44 , 68 , 71 ]. As such, any reduction in their prevalence should be viewed as a positive outcome.…”

Section: Discussionmentioning

confidence: 99%

Effect of Mannan-rich fraction supplementation on commercial broiler intestinum tenue and cecum microbiota

et al. 2022

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Background The broiler gastrointestinal microbiome is a potent flock performance modulator yet may also serve as a reservoir for pathogen entry into the food chain. The goal of this project was to characterise the effect of mannan rich fraction (MRF) supplementation on microbiome diversity and composition of the intestinum tenue and cecum of commercial broilers. This study also aimed to address some of the intrinsic biases that exist in microbiome studies which arise due to the extensive disparity in 16S rRNA gene copy numbers between bacterial species and due to large intersample variation. Results We observed a divergent yet rich microbiome structure between different anatomical sites and observed the explicit effect MRF supplementation had on community structure, diversity, and pathogen modulation. Birds supplemented with MRF displayed significantly higher species richness in the cecum and significantly different bacterial community composition in each gastrointestinal (GI) tract section. Supplemented birds had lower levels of the zoonotic pathogens Escherichia coli and Clostridioides difficile across all three intestinum tenue sites highlighting the potential of MRF supplementation in maintaining food chain integrity. Higher levels of probiotic genera (eg. Lactobacillus and Blautia) were also noted in the MRF supplemented birds. Following MRF supplementation, the cecum displayed higher relative abundances of both short chain fatty acid (SFCA) synthesising bacteria and SCFA concentrations. Conclusions Mannan rich fraction addition has been observed to reduce the bioburden of pathogens in broilers and to promote greater intestinal tract microbial biodiversity. This study is the first, to our knowledge, to investigate the effect of mannan-rich fraction supplementation on the microbiome associated with different GI tract anatomical geographies. In addition to this novelty, this study also exploited machine learning and biostatistical techniques to correct the intrinsic biases associated with microbiome community studies to enable a more robust understanding of community structure.

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“…DNA template from the broth enriched samples was prepared using QIAamp DNA Stool Mini Kit (Qiagen, Hilden, Germany) according to manufacturer's instructions. The DNA templates were investigated for the presence of stx 1 , stx 2 , eaeA , and ehxA genes using an mPCR method (Paton & Paton, 1998), conducted as previously described (Onyeka et al, 2020).…”

Section: Methodsmentioning

confidence: 99%

“…Suspect colonies were streaked on nutrient agar plates and were confirmed with mPCR to identify virulence markers stx 1 , stx 2 , eaeA , and ehxA genes. Serotyping was done using conventional serotyping method (Onyeka et al, 2020; Ørskov & Ørskov, 1984).…”

Section: Methodsmentioning

confidence: 99%

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Prevalence and patterns of fecal shedding of Shiga toxin–producing Escherichia coli by cattle at a commercial feedlot in South Africa

Onyeka

Adesiyun

Keddy

et al. 2021

Journal of Food Safety

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Healthy colonized cattle are the major reservoir of Shiga toxin-producing Escherichia coli (STEC) and play a key role in the entry point of the pathogen into the beef chain. Excretion rates and the concentration of the pathogen in feces influence the epidemiology and transmission of the pathogen within herds and to humans. This study evaluated the prevalence and dynamics of fecal shedding of STEC by cattle in a commercial feedlot in Gauteng, South Africa. An initial cross-sectional survey was conducted; fecal samples were obtained from 106 randomly selected weaned beef calves on arrival at the feedlot using polymerase chain reaction (PCR) to screen by detecting stx 1 and stx 2 genes. Subsequently, a longitudinal study was conducted, and 15 STEC-positive and 11 STEC-negative cattle were sampled monthly and followed to slaughter. STEC O157 and non-O157 were enumerated in samples using commercial chromogenic agar. Initial prevalence of STEC shedding was 27% (29/106; 95% CI [19, 37%]). All 26 cattle shed STEC intermittently or continuously during the study period, all except one were supershedders (≥4 log 10 CFU/g) at one or more samplings, and 19 (73%) were persistent or intermittent super-shedders. Of the 38 STEC isolates recovered, 15 (39%) were serotypeable, representing 11 non-O157 serogroups, including O101, O168, O178, and O68. The most frequent virulence combination profile was stx 1 + eaeA + ehxA (n = 12; 32%). This study confirms the occurrence and variability of STEC super-shedding in feedlot cattle and highlights that super-shedding is not limited to STEC O157. It also shows their public health significance. | INTRODUCTIONShiga toxin-producing Escherichia coli (STEC) has emerged as an important foodborne pathogen globally and has significantly impacted the beef industry and public health (Callaway, Edrington, Loneragan, Carr, & Nisbet, 2013). Healthy colonized cattle, among other ruminants, are the major reservoir of STEC (Munns et al., 2015), and they play a key role in the entry point of the pathogen into the beef chain (Heiman, Mody, Johnson, Griffin, & Gould, 2015). Beef and beef products are frequently identified as a major risk factor for STEC infections and are thus of public health importance, although other sources such as food crops, water, and environment contribute to infection (Heiman et al., 2015). Majowicz et al. (2014) estimated that STEC (O157 and non-O157) is responsible for 2,801,000 acute illnesses annually, resulting in 3,890 cases of hemolytic uremic syndrome (HUS), 270 cases of end-stage renal disease, and 230 deaths globally. E. coli O157:H7 has been recognized as the serotype most commonly associated with severe infections in both large and sporadic outbreaks (Munns

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Shiga Toxin–Producing Escherichia coli Contamination of Raw Beef and Beef-Based Ready-to-Eat Products at Retail Outlets in Pretoria, South Africa

Cited by 19 publications

References 43 publications

Circulation of Shiga Toxin-Producing Escherichia coli Phylogenetic Group B1 Strains Between Calve Stable Manure and Pasture Land With Grazing Heifers

Circulation of Shiga Toxin-Producing Escherichia coli Phylogenetic Group B1 Strains Between Calve Stable Manure and Pasture Land With Grazing Heifers

Effect of Mannan-rich fraction supplementation on commercial broiler intestinum tenue and cecum microbiota

Prevalence and patterns of fecal shedding of Shiga toxin–producing Escherichia coli by cattle at a commercial feedlot in South Africa

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