Thesis (Ph.D.)--Aberdeen University, 2008. / Title from web page (viewed on Apr. 21, 2009). Includes bibliographical references.

The rural population of Grampian was reported to be two times more likely to suffer from <i>E. coli</i> O157 infection than the urban population. <i>E. coli</i> O157 was isolated from minced beef and lamb sampled in butcher shops and supermarkets in rural and urban areas, environmental samples (sheep and cattle faeces on farms) and tap water from private water supplies in the countryside using enrichment of sample, followed by immunomagnetic separation and culture on CT-SMAC agar. Clinical <i>E. coli</i> O157 isolates were recovered from patients in parallel. All <i>E. coli</i> O157 were genotyped by multilocus variable number of tandem repeats analysis (MLVA). Results from the meat survey (Nov04-Aug06) revealed a very low incidence of <i>E. coli </i>O157 in minced meat i.e. 0.75 % (4/530). The winter <i>E. coli</i> O157 sheep study (Jan-Mar05) revealed a group prevalence of 42.8 % and an individual animal prevalence of 5.8 %, consistent with a previous summer study (40 % and 6.5 % respectively) and the cattle farm prevalence was 22 % (Oct06-Jun07), consistent with previous prevalence studies in Scotland. According to MLVA data analysis, it appears that the rural community becomes ill through ingestion of <i>E. coli</i> O157 originating mostly from cattle, from which, a small proportion are infected by drinking water contaminated by cattle. Four human cases of infection living in urban areas shared the same MLVA types as rural human cases emphasising the fact that both populations can become ill from the same source i.e. city dwellers visiting the countryside or by a food widely distributed. The rest of the urban cases MLVA types were significantly different from cattle and sheep types and another source of infection was proposed i.e. travel outwith Grampian or ingestion of food produced in other countries.

Campylobacter is the most commonly reported bacterial cause of gastrointestinal disease in developed countries. Campylobacteriosis is an infectious disease that causes severe diarrhoea, abdominal cramps, vomiting, blood in stools and fever, along with the inability to carry out normal activities for an estimated 3-5 days. Long term sequelae associated with Campylobacter infection includes Guillain Barré syndrome, irritable bowel syndrome and reactive arthritis. The incidence of human campylobacteriosis in the Grampian region was 138.8 per 100,000 people in 2011 which was one of the highest incidence rates within Scotland. Identified areas of limited knowledge in Campylobacter research include: population exposure to risk factors, financial burden and public acceptability of interventions to reduce Campylobacter in the poultry process. This thesis utilises questionnaire methods to gather data from the Grampian population to expand our knowledge in these research areas to assist in the reduction of human campylobacteriosis.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 99-113).

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 105-111). Also available on the Internet.

Verocytotoxigenic Escherichia coli (VTEC) is a major cause of diarrheal infections. It is increasingly associated with the consumption of fresh produce and responsible for several international outbreaks with severe sequelae. Quantitative risk assessment (QRA) aim to evaluate the risk of contamination, quantify uncertainties and identify potential mitigation steps. Current published QRA focus on post-harvest process steps without consideration of pre-harvest factors. This study aimed to identify preharvest knowledge gaps and quantify the potential for growth of VTEC in plant tissue prior to harvest. Risk factors were used to develop a QRA for VTEC O157:H7 in ready-to-eat (RTE) salad from farm-to-fork. Plant host metabolites were analysed by mass spectrometry and chromatography. Further plant and bacteria derived factors involved in pre-harvest colonisation were determined and implemented into a QRA. The burden of disease was estimated as the probability of illness by consuming RTE salad in the United Kingdom (UK). VTEC was shown to frequently internalise into lettuce and spinach to high concentrations. There, it can persist, evade surface decontamination and crosscontaminate equipment and produce during processing. The probability of illness was estimated to be 2.66 * 10-5 for lettuce and 1.51 * 10-5 for spinach. Internalisation was determined as the driving factor for 1820 illnesses per year in the UK associated with the consumption of lettuce and 950 with spinach, respectively. Mitigation steps had limited impact on internalised VTEC O157:H7 and mostly reduced external bacteria. Outputs from the QRA indicate the insufficiency of current mitigation steps to reduce internal VTEC O157:H7 and highlights the need for advanced decontamination procedures. The QRA tool can be used for the development of industrial guidelines in order to improve food safety in the UK and Europe.

Approximately 2-4 billion cases of infectious diarrhoea occur every year, with the highest numbers recorded in sub-Saharan Africa. It remains the most common public health issue among children in developing nations. The purpose of this research was to unfold the prevalence of diarrhoeagenic E. coli and Campylobacter pathotypes as well as elucidate their antibiogram characteristics in diarrhoeal stool samples collected in some medical facilities in Eastern Cape Province, South Africa. Two hundred stool samples were collected from both inpatients and outpatients from male and females of all age groups attending selected medical facilities in the study area. Isolation and characterization of both organisms were done using culture based and molecular methods. Antibiotic susceptibility patterns of identified isolates were determined against a panel of 12 antimicrobial agents. One hundred and twenty presumptive E. coli isolates and 42 presumptive isolates of Campylobacter spp. Were isolated. Eighty-two percent (82 percent) of the presumptive E. coli isolates were confirmed as E. coli while 46.3 percent belonged to Campylobacter spp. Pathotyping of the diarrhoeagenic E. coli isolates by Polymerase chain reaction (PCR) showed the following prevalences: DAEC 43 (32 percent), EHEC 18 (17 percent), EIEC 11 (10 percent) and EPEC 18 (17 percent). EAEC and ETEC were not detected, while for Campylobacter spp. 37 (88 percent) were C. jejuni, and C. coli was not detected. A total of 12 (32.4 percent) of the confirmed Campylobacter jejuni isolates were found to possess the fliM gene, 9 (24.3 percent) possessed the flhA gene and only 6 (16.2 percent) harboured the gene flgE2. None were positive for the flaA, flab and flhB genes.The antibiotic resistance patterns observed among the E. coli isolates were high against ampicillin (98.1 percent), chloramphenicol (94.3 percent) and tetracycline (90.6 percent). For Campylobacter spp., resistance observed were: chloramphenicol (91.6 percent), tetracycline (25.2 percent), erythromycin (49.6 percent) and gentamycin (56.4 percent). A lesser resistance against imipenem (35.9 percent) and quinolone (ciprofloxacin) (45.5 percent) were exhibited by the E.coli isolates. 10.8 percent and 20.3 percent of the Campylobacter isolates were resistant to imipenem and ciprofloxacin respectively. The presence of chloramphenicol (CatA1) and tetracycline (tetA) resistance genes were detected in 94 percent and 89 percent of E. coli isolates respectively while 98 percent of Campylobacter spp. Harboured the catA1 resistance gene. It could be deduced from this study that E. coli and Campylobacter spp. are predomiant enteric pathogens as the etiologic agents of diarrhoea in the study community, and that their antimicrobial resistance is high in the study location. The need to develop strategies to prevent infection and control resistant organisms is evident.

Source: Masters Abstracts International, Volume: 47-02, page: 0989. Adviser: Pamela M. Diamond. Includes bibliographical references.

Escherichia (E) coli infections result in diarrhoea and oedema in growing pigs. Enterotoxigenic (ETEC), shigatoxin producing (STEC) and enteroaggregative (EAEC) E. coli have been identified as the principal causes of colibacillosis in most pig production systems. These E. coli use fimbrial and non-fimbrial adhesins to adhere to the intestines and cause infection. Absence or presence of the receptors on the intestinal walls determines the resistance or susceptibility of the host to the E. coli. In other populations, candidate genes linked to the receptors have been found to be associated with resistance/susceptibility to infection and are used in marker-assisted selection programs. This study investigated the presence and prevalence of ETEC, STEC and EAEC and the associated virulence genes in 263 E. coli isolates sampled from Landrace, Large White, Duroc and Indigenous piglets from the Animal Production Institute of the Agricultural Research Council (ARC) in Irene and Middledrift farm in Eastern Cape Province. The study also investigated polymorphisms at six candidate genes associated with two E. coli receptors in the same pig populations. Over 39 % of the isolates tested positive for the E. coli virulent genes investigated. None of the samples had fimbrial adhesins. The mode of attachment of the investigated E. coli was through non-fimbrial adhesins which were found in 49.06% of the isolates. The 106 E. coli isolates were categorized into 25 pathotypes carrying definable and unique combinations of E. coli virulence factors. The resistant allele for Alfa (1) fucosyltransferase 1 (FUT1) M307, a candidate gene for FI8R, was present in less than 1 % of the population. Various mutations of mucin genes MUC4 g.8227, MUC20 c1600 and g.191 were found in the population. Their respective alleles for controlling F4ab/ac E. coli adhesion in pigs were predominant in both breeds. Three loci (FUT1, MUC20 g.191 and MUC20 c.1600) deviated from Hardy Weinberg equilibrium (HWE) in the Indigenous and the Large White breeds. Heterozygotes deficiency and high levels of within breed diversity was observed in these two breeds at the mentioned loci. Overall, the study observed a wide range of toxin and colonisation factors (CFs) giving rise to diverse pathotypes in South African pigs. The absence of fimbrial adhesins suggests a different colibacillosis control program from that previously used. The presence of the resistant alleles in most of the loci investigated was low, however their presence suggest it is possible to use them to generate a resistant population using marker assisted selection. This study serves as a foundation for future pig colibacillosis control and immunity studies in the South African pig herds. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

The prevalence and antibiotic resistant profiles of shiga-toxin producing Escherichia coli 0157 strains isolated from faeces samples of cattle, pigs and human stool samples were determined. The strains were further characterised by molecular methods for the presence of shiga-toxin virulence genes and antibiotic resistant genes. Seventy-six Escherichia coli 0157 strains were isolated and the prevalence was higher among E. coli isolated from faeces from pigs (44.2% to 50%) than those from cattle faeces (5.4% to 20.0%) or human stool samples (7 .5%). On testing E. coli 0157 isolates for their resistance to 9 antimicrobial agents, multiple antibiotic resistance (MAR) was observed in all of the isolates arising from resistance to three or more antibiotics. Seventy (92.1 %) of the E. coli 0157 isolated from humans, cattle and pigs were resistant to tetracycline. 73 (96.1 %) were resistant to sulphamethoxazole, 63 (82.9%) were resistant to erythromycin. 40 (52.6%) were resistant to streptomycin and 26 (34.2%) were resistant to ampicillin. The highest frequency of resistance was observed among the human isolates (n=3 ), where 3 (I 00%) of the isolates were resistant to tetracycline, sulphamethoxazole, erythromycin and ampicillin. Furthermore, among the pig isolates (n=60), 58 (96. 7%) were resistant to tetracycline, 57 (95%) were resistant to sulphamethoxazole, 47 (78.3%) were resistant to erythromycin. 38 (63.3%) were resistant to streptomycin and 22 (36. 7%) were resistant to ampicillin. The MAR phenotypes S-Smx-T-E, Smx-T-Ap and Smx-T-E were the dorminant phenotypes among the E. coli 0157 isolated from the faeces samples of communal pigs in 30.4%, 21 .7% and 17.4% of these isolates, respectively. However, phenotypes Smx-T -E and S-Smx-T-E-Ne were identified at I6.2% and 10.8%, respectively within the isolates obtained from commercial pig faeces. The phenotype Smx-T-E was the only MAR phenotype identified among the E. coli 0157 isolated from the faecal samples of commercial cattle at Lichtenburg. Furthermore, MAR phenotypes Smx-T-E-C, K-S-Smx-T-E, S-Smx-T-E and Smx-T-E-Ap were obtained at 25%, respectively for the isolates obtained from communal cattle at Mogosane while Smx-T-E-Ap was the dorminant (66.7%) phenotype among the isolates of human origin. The phenotype Smx-T fom1ed the basis of all the MAR phenotypes obtained and this was similar to the percentage antibiotic resistance data. The distribution of the resistant determinants for tetracycline was determined by PCR analysis in resistant isolates. A tetB gene was detected in E. coli 0157 of pig origin. Based on the characterisation of 30 isolates for the presence of STEC virulence genes by PCR, 18 (60%) possessed the hlyA gene, 7 (23.7%) possessed the eae gene and 5 ( 16. 7%,) harboured both genes. The average MAR indices for pig, cattle and human E. coli 0157 isolates were 0.4n2, 0.3419 and 0.4814, respectively. Among the cattle isolates, the group MAR index was highest for the communal (Mogosane) population while the values for the commercial populations at Lichtenburg and Rustenburg were 0.33 and 0.22, respectively. £. coli 0157 isolated from pigs revealed MAR index results that were 0.508 and 0.415 for the commercial and communal populations respectively and 0.1851 for the E. coli control strains. Characterisation by cluster analysis to determine the commonness and resolve differences between the E. coli 0157 isolated from the Various sources revealed a close association between pig (Tlapeng and Mareetsane), cattle (Mogosane) and human isolates. Interestingly, E. coli 0157 isolated from pigs occurred at the highest frequency in all the clusters. which suggested their role in the dissemination of resistant determinants. / MSc. (Agric.) North-West University, Mafikeng Campus, 2006