Thesis (MSc. (Veterinary Science))--University of Pretoria, 2005. / Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains viii, 90 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 59-66).

The sub-therapeutic use of antibiotics for growth promotion in food animal production, has engendered substantial debate on the dissemination of antibiotic resistance via the food chain, specifically, the probability of antibiotic use in food production creating a reservoir of resistant bacteria and/or resistance genes that may spread to humans thereby limiting the therapeutic value of antimicrobial drugs. In the absence of any surveillance programme on food-borne bacteria in South Africa, this study focussed on Campylobacter spp. in poultry and encompassed a literature review on the prevailing debate on the dissemination of antibiotic resistance via the food chain, a phenotypic observational study on the prevalence and antibiotic resistance profiles of Campylobacter spp. isolated within and across different poultry farming systems and a genotypic component that covered identification methods, plasmid profile determination and strain typing. Identification methods for Campylobacter spp., viz, biochemical tests and matrix assisted laser desorption ionization- time of flight (MALDI-TOF) mass spectrometry was compared to the PCR which is considered the gold standard as a molecular method of identification. The MALDI-TOF was shown to be superior to the biochemical tests for the identification of C. coli but equivalent to the biochemical tests for C. jejuni. Of the 363 samples collected in total, the frequency of thermophilic Campylobacter was 68 % in rural farms (or informally reared poultry), 47 % in both commercial free-range and industrial broilers and the highest in industrial layers at 94 %. Antibiotic resistance analysis showed that isolates from the rural farming systems were significantly (P < 0.01) more susceptible to ciprofloxacin, tetracycline and erythromycin when compared to the other farming systems. Significant (P < 0.001) antibiotic resistance differences were detected between broilers (5 - 8 week lifespan), and layers (36 - 52 week lifespan) for gentamicin, ciprofioxacin and tetracycline. Plasmids were fonnd be harboured by isolates in all the farming systems; in 84 % of isolates from free-range broilers, 77 % of isolates from industrial broilers, 83 % of isolates from industrial layer hens and 75 % of isolates from the rural farming system. The PFGE genotyping of 42 Campylobacter isolates generated 39 SmaI types. Substantial and substantive genetic diversity was observed between and within farming systems. The lack of correlations amongst the parameters within and between farming systems attested to the diversity and complexity of phenotypes and genotypes and indicated de novo evolution in response to antibiotic selection pressure and animal husbandry practices. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2013.

Thesis(M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.

Thesis--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 88-101).

Thesis (Ph.D.)--Aberdeen University, 2008. / Title from web page (viewed on June 26, 2009). Includes bibliographical references.

>Magister Scientiae - MSc / Campylobacter species are the most common bacteria associated with acute diarrhoea and is responsible for 400 to 500 million reported cases globally. It is not uncommon for 35% to 85% of chicken flocks to be infected with campylobacters and it is because of this high prevalence that chicken is considered to be the primary source of Campylobacter contamination in the domestic setting. Therefore, a very high risk of acquiring campylobacteriosis is associated with the mishandling and consumption of contaminated chicken. The present study had isolated a total number of 156 Campylobacter isolates, of which 102 isolates were C. jejuni and 51 were C. coli. The speciation of 3 Campylobacter isolates could not be determined. It had shown that there is a high prevalence of Campylobacter in South African chicken. Retail chicken (n = 84) has a lower prevalence of 27% whereas chicken sampled directly from the abattoir (n = 182), but also intended for human consumption, had an average prevalence of 73%. It also showed that free range chicken (n = 118) has a higher prevalence (average of 79%) of Campylobacter than commercial chicken (n = 64) (average of 56%). It is for this reason that free range chicken is not always the safer option considering that the purchasing of free range chicken is becoming more popular for health reasons. There is no standardized universal isolation protocol for Campylobacter species and the current isolation techniques creates a bias for the optimal growth of C. jejuni and C. coli, the two thermotolerant species most commonly associated with human illnesses. Recently, the non-selective Cape Town Protocol was designed for efficient isolation of campylobacters from clinical samples and proved to be superior to the former techniques in the isolation of the thermotolerant campylobacters as well as emerging campylobacters. However, the protocol is not suited to the isolation of Campylobacter from food samples. This study successfully optimized the Cape Town protocol by incorporating the use of the selective Bolton broth for the recovery and enrichment of injured cells from raw chicken samples. The technique proved to be equal in isolation efficiency to the ISO 1272-1:2006 method but loses its ability to recover all campylobacters that may be present in the food sample. It is for this reason that a non selective enrichment broth should be sought but the technique boasts superiority over the ISO 10272-1:2006 method in that it reduces the time in obtaining the results at least by 48 h and is more cost effective. / National Research Foundation (NRF)

This epidemiological investigation focussed on <i>Campylobacter jejuni </i>and <i>Campylobacter coli</i> in the north east of Scotland (Grampian). Scotland, in 2007, had an annual incidence of 101.5 cases/100,000 people, while in Grampian this figure was 120/100,000.  <i>C. jejuni </i>and <i>C. coli </i>are ubiquitous and are natural commensals of a range of animals, therefore understanding the epidemiology of these organisms involves identifying their putative sources and monitoring their dynamics in such hosts.  In this study, the use of various epidemiological tools showed that humans are infected from different sources and notably by chicken. Between 2001 and 2006, the population structure of <i>Campylobacter </i>in retail chicken changed  more than in humans, as shown by characterisation by Multilocus sequence typing (MLST).  There was however a high degree of overlap between these respective strains suggesting that chickens are a major source of human infection.  Furthermore, comparison of the same strains using antimicrobial resistance profiles revealed the same commonality of strains. Infection in the high risk 0-4 year old age group was shown to be attributable mainly to chicken in an urban environment but more attributable to cattle in rural areas.  This may reflect relative rates of exposure to these important sources of <i>Campylobacter.</i> Characterisation of a large outbreak in north east Scotland using various typing techniques identified chicken liver paté as a vehicle for <i>C. jejuni </i>infection; multiple strains were identified in the food and more than one patient displayed co-infection with different strains. These investigations have provided useful information which contributes to the overall surveillance of human campylobacteriosis and the epidemiology of <i>Campylobacter </i>in different hosts.

Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographic references.

Thesis--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 67-77).