Occurrence and characterization of seven major Shiga toxin‐producing <i>Escherichia coli</i> serotypes from healthy cattle on cow–calf operations in South Africa

Mainga, Alfred O.; Cenci‐Goga, Beniamino T.; Malahlela, Mogaugedi N.; Tshuma, Takula; Kalake, Alan; Karama, Musafiri

doi:10.1111/zph.12491

Cited by 18 publications

(19 citation statements)

References 63 publications

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“…Non-O157 E. coli that possess a high proportion of stx2 to stx1 genes as documented in this study have been identified in other studies from South Africa [57], Iran [58] and the United States [59]. However, this observation is contrary to the studies conducted in Western Canada [60] and Europe [61], where non-O157 isolates have been found to harbour more stx1 - than stx2 genes.…”

Section: Discussioncontrasting

confidence: 88%

Characterization of Non-O157 Escherichia coli from Cattle Faecal Samples in the North-West Province of South Africa

et al. 2019

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Escherichia coli are commensal bacteria in the gastrointestinal tract of mammals, but some strains have acquired Shiga-toxins and can cause enterohemorrhagic diarrhoea and kidney failure in humans. Shiga-toxigenic E. coli (STEC) strains such as E. coli O157:H7 and some non-O157 strains also contain other virulence traits, some of which contribute to their ability to form biofilms. This study characterized non-O157 E. coli from South African cattle faecal samples for their virulence potential, antimicrobial resistance (AMR), biofilm-forming ability, and genetic relatedness using culture-based methods, pulsed-field gel electrophoresis (PFGE), and whole genome sequencing (WGS). Of 80 isolates screened, 77.5% (62/80) possessed Shiga-toxins genes. Of 18 antimicrobials tested, phenotypic resistance was detected against seven antimicrobials. Resistance ranged from 1.3% (1/80) for ampicillin-sulbactam to 20% (16/80) for tetracycline. Antimicrobial resistance genes were infrequently detected except for tetA, which was found in 31.3% (25/80) and tetB detected in 11.3% (9/80) of isolates. Eight biofilm-forming associated genes were detected in STEC isolates (n = 62) and two non-STEC strains. Prevalence of biofilm genes ranged from 31.3% (20/64) for ehaAβ passenger to 100% for curli structural subunit (csgA) and curli regulators (csgA and crl). Of the 64 STEC and multi-drug resistant isolates, 70.3% (45/64) and 37.5% (24/64) formed strong biofilms on polystyrene at 22 and 37 °C, respectively. Of 59 isolates screened by PFGE, 37 showed unique patterns and the remaining isolates were grouped into five clusters with a ≥90% relatedness. In silico serotyping following WGS on a subset of 24 non-O157 STEC isolates predicted 20 serotypes comprising three novel serotypes, indicating their diversity as potential pathogens. These findings show that North West South African cattle harbour genetically diverse, virulent, antimicrobial-resistant and biofilm-forming non-O157 E. coli. Biofilm-forming ability may increase the likelihood of persistence of these pathogens in the environment and facilitate their dissemination, increasing the risk of cross contamination or establishment of infections in hosts.

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Section: Discussioncontrasting

confidence: 88%

Characterization of Non-O157 Escherichia coli from Cattle Faecal Samples in the North-West Province of South Africa

et al. 2019

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“…with stx virulence genes incorporated into the bacterial genome, and as free stx-encoding bacteriophage. Such high carriage by cattle has been reported in several countries, including the US, Canada, Europe, and Australia (39)(40)(41)(42)(43)(44). Across all these studies, the prevalence of stx2 is greater than that of stx1, similar to our own observations.…”

Section: Herd Risk Analysissupporting

confidence: 90%

Prevalence and Epidemiology of Non-O157 Escherichia coli Serogroups O26, O103, O111, and O145 and Shiga Toxin Gene Carriage in Scottish Cattle, 2014–2015

Hoyle

Keith

Williamson

et al. 2021

Appl Environ Microbiol

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Cattle are a reservoir for Shiga toxin-producing Escherichia coli (STEC), zoonotic pathogens that cause serious clinical disease. Scotland has a higher incidence of STEC infection in the human population than the European average. The aim of this study was to investigate the prevalence and epidemiology of non-O157 serogroups O26, O103, O111, O145, and Shiga toxin gene carriage, in Scottish cattle. Faecal samples (n = 2783) were collected from 110 herds between 2014-2015 and screened by real-time PCR. Herd-level prevalence (95% CI) for O103, O26 and O145 was estimated as 0.71 (0.62, 0.79), 0.43 (0.34, 0.52) and 0.23 (0.16, 0.32), respectively. Only two herds were positive for O111. Shiga toxin prevalence was high in both herds and pats, particularly for stx2 (herd-level: 0.99, 95% CI: 0.94, 1.0). O26 bacterial strains were isolated from 36 herds on culture. Fifteen herds yielded O26 stx-positive isolates that additionally harboured the intimin gene; six of these herds shed highly pathogenic stx2a-positive strains. Multiple serogroups were detected in herds and pats, with only 25 herds negative for all serogroups. Despite overlap in detection, regional and seasonal effects were observed. Higher herd prevalence for O26, O103 and stx1 occurred in the South West and this region was significant for stx2 at the pat-level (P = 0.015). Significant seasonal variation was observed for O145 prevalence, highest in autumn (P = 0.032). Negative herds were associated with Central Scotland and winter. Herds positive for all serogroups were associated with autumn, larger herd size and were not housed at sampling. IMPORTANCE Cattle are reservoirs for Shiga toxin Escherichia coli (STEC), bacteria shed in animal faeces. Human are infected through consumption of contaminated food or water, and by direct contact, causing serious disease and kidney failure in the most vulnerable. The contribution of non-O157 serogroups to STEC illness was underestimated for many years, due to the lack of specific tests. Recently non-O157 human cases have increased, with O26 STEC of particular note. It is therefore vital to investigate the level and composition of non-O157 in the cattle reservoir, and compare to historical levels and the clinical situation. In this study we found cattle prevalence high for toxin, as well as O103 and O26 serogroups. Pathogenic O26 STEC were isolated from 14% of study herds, with toxin subtypes similar to that seen in Scottish clinical cases. This study highlights the current risk to public health from non-O157 STEC in Scottish cattle.

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“…Currently, STEC surveillance in South Africa remains passive and STEC disease in South Africa may be underestimated due to lack of active surveillance and/or underreporting. In addition, with cattle being an important STEC reservoir [44], the apparent sporadic nature of the disease in humans may be an inaccurate reflection of the true prevalence of STEC infection in humans. In this study, STEC isolates that were implicated in sporadic human disease in South Africa between 2006 and 2013 were characterized for virulence-associated genes and antimicrobial resistance profiles.…”

Section: Discussionmentioning

confidence: 99%

“…The eaeA gene was observed in the following serotypes: STEC O5:HNT, O26:H11, O111:H8, O118:H16, O157:H7 and ONT:H8. The high frequency of eaeA in these human STEC isolates is in sharp contrast with the very low rates of eaeA found in STEC isolates from cattle in South Africa [44], which are considered an important STEC reservoir, suggesting that only a small subset of cattle STEC that are eaeA positive with a high capacity of being easily transmitted to humans may be involved in human disease in South Africa.…”

Section: Discussionmentioning

confidence: 99%

Virulence Characteristics and Antimicrobial Resistance Profiles of Shiga Toxin-Producing Escherichia coli Isolates from Humans in South Africa: 2006–2013

Karama

Cenci‐Goga

Malahlela

et al. 2019

Toxins

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Shiga toxin-producing Escherichia coli (STEC) isolates (N = 38) that were incriminated in human disease from 2006 to 2013 in South Africa were characterized by serotype, virulence-associated genes, antimicrobial resistance and pulsed-field gel electrophoresis (PFGE). The isolates belonged to 11 O:H serotypes. STEC O26:H11 (24%) was the most frequent serotype associated with human disease, followed by O111:H8 (16%), O157:H7 (13%) and O117:H7 (13%). The majority of isolates were positive for key virulence-associated genes including stx1 (84%), eaeA (61%), ehxA (68.4%) and espP (55%), but lacked stx2 (29%), katP (42%), etpD (16%), saa (16%) and subA (3%). stx2 positive isolates carried stx2c (26%) and/or stx2d (26%) subtypes. All pathogenicity island encoded virulence marker genes were detected in all (100%) isolates except nleA (47%), nleC (84%) and nleD (76%). Multidrug resistance was observed in 89% of isolates. PFGE revealed 34 profiles with eight distinct clusters that shared ≥80% intra-serotype similarity, regardless of the year of isolation. In conclusion, STEC isolates that were implicated in human disease between 2006 and 2013 in South Africa were mainly non-O157 strains which possessed virulence genes and markers commonly associated with STEC strains that have been incriminated in mild to severe human disease worldwide. Improved STEC monitoring and surveillance programs are needed in South Africa to control and prevent STEC disease in humans.

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Occurrence and characterization of seven major Shiga toxin‐producing Escherichia coli serotypes from healthy cattle on cow–calf operations in South Africa

Cited by 18 publications

References 63 publications

Characterization of Non-O157 Escherichia coli from Cattle Faecal Samples in the North-West Province of South Africa

Characterization of Non-O157 Escherichia coli from Cattle Faecal Samples in the North-West Province of South Africa

Prevalence and Epidemiology of Non-O157 Escherichia coli Serogroups O26, O103, O111, and O145 and Shiga Toxin Gene Carriage in Scottish Cattle, 2014–2015

Virulence Characteristics and Antimicrobial Resistance Profiles of Shiga Toxin-Producing Escherichia coli Isolates from Humans in South Africa: 2006–2013

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