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Prof
Madoroba, Evelyn
Department: Biochemistry and Microbiology
Research Interest(s): Antimicrobial resistance, Microbial genomics, Foodborne and zoonotic pathogens, Bioprospecting for antimicrobial compounds from marine environmens.
Active Research Project(s): Bioprospecting for marine microorganisms with antimicrobial properties against salmonella species and campylobacter species from poultry sources.
Development of fermented ready to prepare sorghum flour and accessory products.
Biography: Professor Evelyn Madoroba is a Professor of Microbiology in the Department of Biochemistry and Microbiology at the University of Zululand. She rated by the National Research Foundation of South Africa as a researcher in category C2. She has published over 35 peer reviewed manuscripts. Prof Madoroba has published two book chapters and successfully completed National Surveillance of nine foodborne pathogens in meat and meat products in South Africa. She has successfully supervised/ co-supervised 10 MSc and three PhD students. Shei s currently supervising/ co-supervising nine postgraduate students. Professor Evelyn Madoroba has contributed to more than 30 local and international conferences.
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- Listeria monocytogenes is a zoonotic food-borne pathogen that is associated with serious public health and economic implications. In animals, L. monocytogenes can be associated with clinical listeriosis, which is characterised by symptoms such as abortion, encephalitis and septicaemia. In human beings, listeriosis symptoms include encephalitis, septicaemia and meningitis. In addition, listeriosis may cause gastroenteric symptoms in human beings and still births or spontaneous abortions in pregnant women. In the last few years, a number of reported outbreaks and sporadic cases associated with consumption of contaminated meat and meat products with L. monocytogenes have increased in developing countries. A variety of virulence factors play a role in the pathogenicity of L. monocytogenes. This zoonotic pathogen can be diagnosed using both classical microbiological techniques and molecular-based methods. There is limited information about L. monocytogenes recovered from meat and meat products in African countries. This review strives to: (1) provide information on prevalence and control measures of L. monocytogenes along the meat value chain, (2) describe the epidemiology of L. monocytogenes (3) provide an overview of different methods for detection and typing of L. monocytogenes for epidemiological, regulatory and trading purposes and (4) discuss the pathogenicity, virulence traits and antimicrobial resistance profiles of L. monocytogenes.
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- Meat products have been implicated in many listeriosis outbreaks globally, however there is a dearth of information on the diversity of L. monocytogenes isolates circulating in food products in South Africa. The aim of this study was to investigate the population structure of L. monocytogenes isolated in the meat value chain within the South African market. Based on whole-genome sequence analysis, a total of 217 isolates were classified into two main lineage groupings namely lineages I (n = 97; 44.7%) and II (n = 120; 55.3%). The lineage groups were further differentiated into IIa (n = 95, 43.8%), IVb (n = 69, 31.8%), IIb (n = 28, 12.9%), and IIc (n = 25, 11.5%) sero-groups. The most abundant sequence types (STs) were ST204 (n = 32, 14.7%), ST2 (n = 30, 13.8%), ST1 (n = 25, 11.5%), ST9 (n = 24, 11.1%), and ST321 (n = 21, 9.7%). In addition, 14 clonal complex (CCs) were identified with over-representation of CC1, CC3, and CC121 in “Processed Meat-Beef”, “RTE-Poultry”, and “Raw-Lamb” meat categories, respectively. Listeria pathogenic islands were present in 7.4% (LIPI-1), 21.7% (LIPI-3), and 1.8% (LIPI-4) of the isolates. Mutation leading to premature stop codons was detected in inlA virulence genes across isolates identified as ST121 and ST321. The findings of this study demonstrated a high-level of genomic diversity among L. monocytogenes isolates recovered across the meat value chain control points in South Africa.
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- A cross-sectional study was conducted to determine the prevalence of and factors associated with Shiga toxin–producing Escherichia coli (STEC) in raw beef and ready-to-eat (RTE) beef products sold in 31 retail outlets in Pretoria, South Africa, and nearby areas. A total of 463 beef and RTE samples were screened for four STEC virulence genes (stx1, stx2, eaeA, and hlyA) and seven O-serogroups (O113, O157, O26, O91, O145, O111, and O103) with a multiplex PCR assay. The total aerobic plate count (TAPC) per gram was also determined. A total of 38 STEC isolates were recovered and characterized by conventional PCR assay and serotyping. The overall prevalence of STEC in the beef and RTE samples tested was 16.4% (76 of 463 samples; 95% confidence interval, 13 to 20%). The prevalence of STEC differed significantly by product type (P , 0.0001), with the highest prevalence (35%) detected in boerewors (spicy sausage). The STEC prevalences in minced beef, brisket, RTE cold beef, and biltong were 18, 13, 9, and 5%, respectively. The most frequently detected stx gene was stx2 (13%), and STEC serogroups from recovered isolates were detected at the following prevalences: O2, 15%; O8, 12%; O13, 15%; O20, 8%; O24, 3%; O39, 3%; O41, 8%; O71, 3%; O76, 3%; O150, 12%; and O174, 3%. A high proportion (77%) of the samples had TAPCs that exceeded the South African microbiological standards for meat export (5.0 log CFU/g). The prevalence of O157 STEC (16%) and the diversity of non-O157 STEC serogroups found in five common beef-based products from retail outlets in South Africa suggest exposure of raw beef and beef products to multiple contamination sources during carcass processing and/or cutting and handling at retail outlets. These data provide direct estimates of the potential health risk to consumers from undercooked contaminated products and indicate the need to improve sanitary practices during slaughter and processing of beef and beef-based RTE products. A risk-based surveillance system for STEC may be needed
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- 2020| ElsevierBacillus anthracis, the aetiological agent of anthrax, is regarded as a highly monomorphic pathogen that presents a low genetic diversity using standard molecular techniques. Whole genome sequencing and single nucleotide polymorphisms (SNPs) are definitive signatures for subtyping of B. anthracis. Here we employed whole genome single nucleotide polymorphism (wgSNP) analysis to investigate the genetic diversity of B. anthracis in the historically endemic region of Northern Cape Province (NCP), South Africa. Twenty-six isolates from anthrax outbreaks that occurred between 1998 and 2008/9 in NCP as well as from Namibia-South Africa Transfontier Conservation area and Botswana were compared to global B. anthracis genomes. Most NCP B. anthracis strains (n = 22) clustered in the A.Br.003/004 (A.Br.101) branch and are closely related to the Zimbabwe and Mozambique strains (A.Br.102 branch). A total of 4923 parsimony informative-SNPs accurately established the A.Br.003/004 phylogenetic relationships of the NCP isolates into two distinct sub-clades and SNP markers designated as A.Br.172 and A.Br.173 were developed. Other NCP strains (n = 2) grouped in the A.Br.001/002 (Sterne) branch while strains (n = 2) from the Namibia-South Africa Transfontier Conservation area and Botswana clustered in A.Br.005/006 (Ancient A) branch. The sequenced B. anthracis strains (A0094, A0096 and A0097) that clustered in the A.Br.064 (V770) clade were isolated from Vaalbos National Park and similar strains have not been isolated. The B. anthracis A0088 strain cluster with the NCP strains in the A.Br.003/004 (A.Br.172) SNP branch which has been isolated in NCP, South Africa. This study highlights the phylogenetic structure of NCP B. anthracis strains with distinctive SNP branches important for forensic tracing and novel SNP discovery purposes. The sequenced strains will serve as a means to further trace the dissemination of B. anthracis outbreaks in NCP, South Africa, and on the continent, as well as for forensic tracking on a global scale.
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- Vermicompost (VC) harbours diverse microbes, including plant growth-promoting microorganisms (PGPM) that are beneficial for sustainable crop production. Hence, this study aimed to analyse bacterial diversity of VC samples as a first highthroughput screening step towards subsequent targeted isolation of potential bacterial inoculum candidates. To achieve this, bacterial communities in VC collected from five production farms were enriched in nutrient-rich media before highthroughput sequence (HTS) analysis of the partial 16S rRNA gene. HTS analysis revealed 572 amplicon sequence variants (ASVs) in all enriched VC samples. Firmicutes, Proteobacteria, Planctomycetes and Bacteroidetes were the most dominant phyla, while Lysinibacillus, Escherichia-Shigella, Bacillus, Pseudomonas, Clostridium sensu stricto 1, Morganella, Vibrio and Aeromonas were the predominant genera across the enriched VC. The presence of Clostridium sensu stricto 1, Escherichia-Shigella and Vibrio genera, which are potentially pathogenic species, suggests the need to improve vermicomposting efficiency and safety. Predicted functional profiling of the bacterial communities using PICRUSt2 showed abundance profiles of nitrogenases, phosphatases and sulfatases. In addition, the potential to produce siderophore, indole acetic acids (IAA) and phytohormone regulator 1-aminocyclopropane-1-carboxylate (ACC) were predicted. Lysinibacillus, Bacillus, Paenibacillus and Pseudomonas were major bacterial communities with potential plant growth-promoting traits and could serve as resources in bacterial inoculum production. The findings in this study provide insight into the community composition, abundance and the potential functional capability of cultivable bacterial species of enriched VC. This study also points to VC as a suitable source of potentially beneficial bacterial candidates for inoculum production
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- Annually, approximately 23,000 cases of food poisoning by Staphylococcus aureus enterotoxins are reported worldwide. The aim of this study was to determine the occurrence and characterize S. aureus on beef and beef products in South Africa. Organ meats (n = 169), raw processed meat (n = 110), raw intact (n = 53), and ready-to-eat meats (n = 68) were obtained from 25 retail outlets. S. aureus was isolated and enumerated according to the ISO 6888-1 method. Identification of the strains was performed by MALDI-TOF MS. The antimicrobial resistance was determined using the disc diffusion test. The presence of methicillin-resistance genes and the staphylococcal enterotoxin genes was determined by PCR. Prevalence was low (13/400; CI 1.7–5) and all but one positive sample were from organ meats. Eight isolates were resistant to at least one antibiotic. Two isolates carried the mecC gene. All the isolates tested positive for seg, seh, sei, and sep, whilst 53.8% were positive for sea. None of the isolates was positive for ser, sej, seb, sec, or sed. The prevalence of S. aureus was low, with organ meats being the most contaminated. The presence of mecC-positive MRSA and of enterotoxins warrants further investigation and risk assessment.
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- Animal health is a prerequisite for global health, economic development, food security, food quality, and poverty reduction, while mitigating against climate change and biodiversity loss. We did a qualitative review of 53 infectious diseases in terrestrial animals with data from DISCONTOOLS, a specialist database and prioritisation model focusing on research gaps for improving infectious disease control in animals. Many diseases do not have any appropriate control tools, but the prioritisation model suggests that we should focus international efforts on Nipah virus infection, African swine fever, contagious bovine pleuropneumonia, peste des petits ruminants, sheeppox and goatpox, avian influenza, Rift Valley fever, foot and mouth disease, and bovine tuberculosis, for the greatest impact on the UN’s Sustainable Development Goals. Easy to use and accurate diagnostics are available for many animal diseases. However, there is an urgent need for the development of stable and durable diagnostics that can differentiate infected animals from vaccinated animals, to exploit rapid technological advances, and to make diagnostics widely available and affordable. Veterinary vaccines are important for dealing with endemic, new, and emerging diseases. However, fundamental research is needed to improve the convenience of use and duration of immunity, and to establish performant marker vaccines. The largest gap in animal pharmaceuticals is the threat of pathogens developing resistance to available drugs, in particular for bacterial and parasitic (protozoal, helminth, and arthropod) pathogens. We propose and discuss five research priorities for animal health that will help to deliver a sustainable and healthy planet: vaccinology, antimicrobial resistance, climate mitigation and adaptation, digital health, and epidemic preparedness.
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- 2022| Mary Ann LiebertConsumption of food that is contaminated with Shiga toxin–producing Escherichia coli (STEC) has been linked to serious foodborne disease outbreaks. Our aim was to provide a descriptive study on the presence and virulence factors of STEC and non-STEC O157 isolates recovered from 2017 diverse meat and meat product samples from all provinces of South Africa (n = 1758) and imported meat from South Africa's major ports of entry (n = 259). A cross-sectional study was undertaken to analyze raw intact meat, raw processed (nonintact) meat, and ready-to-eat (RTE) meat from cattle, game, sheep, pork, and poultry. Isolation was performed using International Organization for Standardization-based microbiological techniques, while detection and characterization were performed using real-time PCR (RT-PCR) and conventional PCR targeting the stx1, stx2, eae, and ehxA genes. A total of 28 of 1758 (1.59%; confidence interval [CI] 1.1–2) samples from the domestic market tested positive (n = 10 Escherichia coli O157:H7; n = 14 Escherichia coli O157: non-H7; and n = 4 non-O157 STEC), while 4/259 (1.54%; CI 0.4–4) samples from ports of entry tested positive for Escherichia coli O157:H7 based on RT-PCR. On average, diverse samples from domestic meat and meat products from cattle showed the highest number of positive samples (22/1758; 1.3%; CI 0.8–2). RT-PCR detected more positive samples (n = 32) compared with culture (n = 17). Sixteen different virulence factor combinations were observed. Our findings demonstrate a relatively low presence of diverse STEC strains along the meat value chain. To our knowledge, this is the first extensive report in South Africa to analyze STEC and non-STEC O157 from local and imported samples from many animal species. This is important as it reveals virulence factors in STEC strains circulating in meat and meat products in South Africa, which contribute to the risk of infection.
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