The contamination of street vended vegetables may occur through the usage of manure and contaminated irrigation water, and the consumption of these vegetables, such as ready-to-eat salads, can cause foodborne diseases in consumers. The objective of this study was to investigate the Enterobacteriaceae diversity in vegetables sold at informal markets in the Johannesburg Metropolis. A total of 201 vegetable samples were purchased from randomly selected street vendors from different regions in the Johannesburg Metropolis and analysed for aerobic growth count and Enterobacteriaceae contamination using Plate Count Agar (PCA), and violet red bile glucose agar (VRBGA), respectively. The diversity of bacterial isolates was analysed using sequencing and phylogenetic analysis. The aerobic bacterial growth counts of vegetables from all the regions ranged from 7.66(±0.759) to 8.37(±0.347) log10 cfu/g and the mean aerobic growth counts of vegetables from Soweto and Yeoville were significantly different (p ≤ 0.05) from those of the other regions, but were not significantly (p > 0.05) different across different vegetable types. The Enterobacteriaceae growth counts in vegetables from all the regions ranged from 5.05 (±0.647) to 5.45 (±0.693) log10 cfu/g. The mean Enterobacteriaceae growth counts of vegetables were not significantly (p > 0.05) across each region and different vegetables types. The predominant Enterobacteria genera were Serratia (35%), followed by Hafnia (21%), Aeromonas (17%), and Pseudomonas (5%). In conclusion, this study shows that the vegetables sold at the informal markets in the Johannesburg Metropolis have high aerobic bacterial growth and Enterobacteriaceae contamination due to poor hygiene practices. The dominant Enterobacteriaceae genera isolated are Aeromonas, Hafnia, Serratia, and Pseudomonas, which could be opportunistic pathogens. It is recommended that the Department of Health improves vending and sanitation facilities, to prevent cross contamination. / Life and Consumer Sciences / M. Sc. (Life Sciences)

Pathogens, such as Escherichia coli and fecal coliforms, are causing the majority of water quality impairments in U.S., making up ~87% of this grouping's violations. Predicting and characterizing source, transport processes, and microbial survival rates is extremely challenging, due to the dynamic nature of each of these components. This research built upon current analytical methods that are used as exploratory tools to predict pathogen indicator counts across regional scales. Using a series of non-parametric methodologies, with spatially explicit predictors, 6657 samples from non-estuarine lotic streams were analyzed to make generalized predictions of regional water quality. 532 frequently sampled sites in the Oregon Coast Range Ecoregion, were parsed down to 93 pathogen sampling sites in effect to control for spatial and temporal biases. This generalized model was able to provide credible results in assessing regional water quality, using spatial techniques, and applying them to infrequently or unmonitored catchments. This model's 56.5% explanation of variation, was comparable to other researchers' regional assessments. This research confirmed linkages to land uses related to anthropogenic activities such as animal operations and agriculture, and general riparian conditions.

Die chronisch-entzündlichen Darmerkrankungen Morbus Crohn und Colitis ulzerosa sind wiederkehrende, nicht heilbare, immunvermittelte Krankheiten unklarer Ursache. Genetische Prädisposition und Umweltfaktoren können die Barrierefunktion der Darmmukosa stören, so dass eine überschiessende Entzündungsreaktion folgt, die durch kommensale Bakterien der normalen Darmflora verstärkt wird. Die Infektion mit H. pylori im Magen kann zu Gastritis, Ulkuskrankheit und der Entstehung von MALT-Lymphomen und Magenkarzinomen führen. An der Erkennung von bakteriellen Bestandteilen im Gastrointestinaltrakt sind Toll-like-Rezeptoren (TLR), als Komponenten des angeborenen Immunsystems maßgeblich beteiligt. In der vorliegenden Arbeit wurden Veränderungen der Bakterienflora bei Ileitis, Colitis und bei Vorliegen einer H. pylori-Infektion im Mausmodell untersucht. Durch eine globale Florenanalyse mit klassischen mikrobiologischen und molekularbiologischen Techniken konnte gezeigt werden, dass die Konzentrationen an Gram-negativen Stäbchenbakterien während der Entzündung in Ileum und Colon anstiegen. Die bakteriellen Faktoren, die eine Ileitis induzierten, wurden durch den Einsatz von gnotobiotischen TLR-defizienten Mäusen mit definierter bakterieller Rekolonisierung ermittelt. Hierbei zeigte sich, dass eine Ileitis durch das LPS von akkumulierenden E. coli über die TLR4-vermittelte Signaltransduktion verstärkt wurde. Die Entzündungsreaktionen konnten durch Behandlung mit Antibiotika oder dem LPS-Antagonisten Polymyxin B gebessert werden. In Folge einer H. pylori-Infektion kam es im Mausmagen zu einer erhöhten Diversität der Bakterienflora durch die Besiedelung mit Bakterienarten, die normalerweise das Colon kolonisieren. Eine derartige Florenverschiebung konnte durch eine Vakzinierung gegen H. pylori verhindert werden. Die Tiermodelle zur T. gondii-induzierten Ileitis und DSS-Colitis erlauben eine reproduzierbare Analyse entzündungsrelevanter Komponenten und damit die Möglichkeit, therapeutische Ansatzpunkte, wie z.B. den Einsatz von Lipopolysaccharid-Inhibitoren, die Blockade von TLR4 oder dem LPS-Bindeprotein oder den Einsatz von Probiotika, unter definierten Bedingungen zu analysieren. / Inflammatory bowel diseases like Crohn´s disease and ulcerative colitis are chronic, relapsing, immunologically mediated disorders with uncertain etiology. Genetic abnormalities and environmental factors may have negative influences on the physiologic barrier function of the intestinal mucosa with inflamamtion coming up after immune response which is aggravated by commensal intestinal bacteria. The infection of H. pylori can cause gastritis and ulcus disease and contribute to the occurence of MALT lymphoma and gastric cancer. Bacterial ligands in the intestine are recognized by toll-like receptors (TLR) which are one component of the innate immune system. This study observed variations of the bacterial flora in mice with ileitis, colitis or H. pylori-infection. Performing a global survey of the intestinal flora combining culture based techniques with molecular methods, it was observed, that the concentration of gram-negative rods is elevated during ileitis or colitis. The bacterial factors, which are capable of inducing ileitis, could be confirmed using gnotobiotic TLR-deficient mice with a defined bacterial recolonization. It was clearly shown that ileitis was aggravated by LPS of accumulating E. coli through a TLR4-mediated signal transduction. The inflammation was ameliorated through antibiotic treatment or after application of the LPS-scavenger polymyxin B. H. pylori infection of mice leads to an increase of bacterial diversity in the stomach and bacterial species which are normally colonize the colon were detected after infection. Vaccination against H. pylori could prevent this diversity shift. The animal models for the T. gondii-induced ileitis and DSS-colitis used in this study offering the reproducible analysis of inflammation relevant components so that new approaches of treatment like inhibition of lipopolysaccharide, blockage of TLR4 or LPS binding protein or application of probiotics could be studied under well defined conditions.

Thesis (Ph. D.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).