4 research outputs found
Molecular profiling and antimicrobial resistance of Shiga toxin-producing Escherichia coli O26, O45, O103, O121, O145 and O157 isolates from cattle on cow-calf operations in South Africa
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.This manuscript is part a
dissertation submitted in the Veterinary Public Health section, Department of Paraclinical Sciences, University
of Pretoria, in partial fulfilment of the requirements for the degree of Master of Science (Veterinary Science). (http://hdl.handle.net/2263/65499)The Gauteng Department of Agriculture and Rural Development (GDARD) (Grant
No. FY 2013/14âA0W907), the Global Disease Detection (GDD) Program of the Centers for Disease Control
and Prevention (CDC) (Grant No. 1U2GGH001874â01) and the National Research Foundation (NRF) of South
Africa Thuthuka (TTK13062619943), Research Technology (RTF14012762427) Funds.https://www.nature.com/srepam2019Paraclinical Science
Virulence characteristics and antimicrobial resistance profiles of Shiga toxin-producing escherichia coli isolates from humans in South Africa : 2006â2013
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.The National Research Foundation (NRF) of South Africa: Thuthuka (TTK13062619943),
Research Technology Fund (RTF14012762427), the Gauteng Department of Agriculture and Rural Development
(GDARD Grants-2013-2015) and the South African Medical Research Council (Self-Initiated Research 2017-2019).https://www.mdpi.com/journal/toxinsam2019Paraclinical Science
Occurrence and characterization of seven major Shiga toxinâproducing Escherichia coli serotypes from healthy cattle on cowâcalf operations in South Africa
Cattle are a major reservoir of Shiga toxinâproducing Escherichia coli. This study investigated the occurrence of seven major STEC serogroups including O157, O145, O103, O121, O111, O45 and O26 among 578 STEC isolates previously recovered from 559 cattle. The isolates were characterized for serotype and major virulence genes. Polymerase chain reaction revealed that 41.7% (241/578) of isolates belonged to STEC O157, O145, O103, O121, O45 and O26, and 33 distinct serotypes. The 241 isolates corresponded to 16.5% (92/559) of cattle that were STEC positive. The prevalence of cattle that tested positive for at least one of the six serogroups across the five farms was variable ranging from 2.9% to 43.4%. Occurrence rates for individual serogroups were as follows: STEC O26 was found in 10.2% (57/559); O45 in 2.9% (16/559); O145 in 2.5% (14/559); O157 in 1.4% (8/559); O121 in 1.1% (6/559); and O103 in 0.4% (2/559). The following proportions of virulence genes were observed: stx1, 69.3% (167/241); stx2, 96.3% (232/241); eaeA, 7.1% (17/241); ehxA, 92.5% (223/241); and both stx1 and stx2, 62.2% (150/241) of isolates. These findings are evidence that cattle in South Africa carry STEC that belong to six major STEC serogroups commonly incriminated in human disease. However, only a subset of serotypes associated with these serogroups were clinically relevant in human disease. Most STEC isolates carried stx1, stx2 and ehxA but lacked eaeA, a major STEC virulence factor in human disease.The Gauteng Department of Agriculture Rural Development (GDARD) (Grant No. FY 2013/14-A0W907), the National Research Foundation (NRF)-Thuthuka Fund, the University of Pretoria, Institutional Research Theme (IRT)-Animal and Zoonotic Diseases (AZD) (Grant No. UP-AZD IRT A0W596), and the Global Disease Detection (GDD) Program of the Centers for Disease Control and Prevention (CDC) (Grant No. 1U2GGH001874-01).http://wileyonlinelibrary.com/journal/zph2019-11-01hj2019Paraclinical SciencesProduction Animal Studie
Occurrence, serotypes and virulence characteristics of Shiga-toxin-producing Esscherichia coli isolates from goats on communal rangeland in South Africa
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% (381/628); stx2, 72.7% (457/628); eaeA, 22.1% (139/628) and hlyA,
78.0% (490/628). Both stx1 and stx2 were found in 33.4% (210/628) of isolates. In conclusion, goats
in South Africa are a reservoir and potential source of diverse STEC serotypes that are potentially
virulent for humans. Further molecular characterization will be needed to fully assess the virulence
potential of goat STEC isolates and their capacity to cause disease in humans.SUPPLEMENTARY MATERIALS : TABLE S1: Association between O group
and H-type(s) among goat STEC Isolates; TABLE S2: Goat STEC major virulence factors and gene
combinations.The National Research Foundation (NRF) of South Africa, the South African Medical Research Council Self-Initiated Research and UNICEF Future Africa-UP One Health for Change research grants-2021.https://www.mdpi.com/journal/toxinsam2023Paraclinical SciencesProduction Animal StudiesVeterinary Tropical Disease