A dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa, in fulfillment of the requirements for the degree, Master of Science in Medicine Johannesburg, 2017 / In South Africa, there is a lack of national surveillance for Campylobacter. Campylobacter infections particularly those caused by Campylobacter jejuni and Campylobacter coli, cause a significant proportion of all diarrhoeal cases. Although diarrhoea caused by Campylobacter is short-lived, belligerent clinical manifestations include C. jejuni-induced Guillain-Barré Syndrome (GBS) which can cause considerable morbidity. Improvements in molecular subtyping methodologies, such as multi-locus sequence typing (MLST) and whole genome sequencing (WGS) based applications have been successfully applied in the field of molecular epidemiology of Campylobacter. Our study proposed to improve the molecular epidemiological understanding of Campylobacter in South Africa using polymerase chain reaction (PCR), WGS, and MLST. Antimicrobial susceptibility profiles of Campylobacter were also investigated. Furthermore, the prevalence of Campylobacter in stool specimens of children (<5 years) with acute diarrhoea and from patients with symptoms of acute flaccid paralysis (AFP) was investigated. A multiplex real-time PCR targeting C. jejuni and C. coli was used to screen a total of 2,341 samples from clinical isolates and clinical specimens associated with various existing surveillance programs. Antimicrobial susceptibility was performed using the Etest method. C. jejuni isolates were further subtyped using MLST based on the analysis of WGS data. In all surveillance programs, C. jejuni was the most predominant species of Campylobacter detected (>77%). Isolates had low prevalence of antimicrobial resistance to erythromycin (10%) and azithromycin (14%), however, ciprofloxacin (53%) and tetracycline (53%) resistance was notable. It was male (54%) children of less than five years of age (35%) who were more frequently associated with campylobacteriosis. A total of 33 different sequence types (STs) were identified through MLST; ST-227 and ST-572 were the most common STs. A total of five different clonal complexes grouped all typable isolates, with ST-206 complex and ST-21 complex being the most common clonal complexes. Strains with new unassigned STs of novel combinations of known alleles (n=8) and novel alleles were identified (n=1). Multiplex real-time PCR proved effective to detect and discriminate Campylobacter species. C. jejuni was the most isolated species during the course of the study. The application of MLST reflected the genetic diversity that exists in C. jejuni strains. The current underrepresentation of Campylobacter burden of disease in South Africa may improve if better diagnosis and surveillance are introduced in South Africa. / MT2017

Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Microbiology and Immunology, 1992

Thesis (Ph.D.) -- University of Adelaide, Dept. of Microbiology and Immunology, 1992.

No description available.

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

No description available.

Thesis (M.Sc.)--Victoria University of Wellington, 2008. / Includes bibliographical references.

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)

Campylobacter is an important human pathogen that colonizes the gut of food producing animals. In this study, the effects of 2-nitro-1-propanol, 2-nitroethanol, nitroethane, and 2-nitro-methyl-propionate (0, 10, and 20 mM) on growth of Campylobacter jejuni were tested during culture in Bolton Broth adjusted to pH 5.6, 7.0, or 8.2. The effects of the nitrocompounds were also tested against C. coli in Bolton Broth but adjusted to pH 8.2 only. Viable cell counts of samples taken at intervals during incubation revealed main effects (P < 0.05) of nitroethane, 2-nitro-1-propanol, 2- nitroethanol, and 2-nitro-methyl-propionate as evidence by reduced survivability of C. jejuni. A marked effect of pH on the survivability of C. jejuni during incubation with all compounds was observed, with greater activity observed at pH 8.2 than at pH 5.6 or 7.0 for nitroethane, 2-nitro-1-propanol, 2-nitroethanol, but not for 2-nitro-methyl-propionate. In the case of 2-nitro-methyl-propionate, survivability of C. jejuni was reduced most at pH 5.6. Except for 2-nitro-methyl-propionate, which was ineffective, all nitrocompounds elicited similar effects on C. coli when cultured at pH 8.2. The effect of nitroethane and 2-nitro-1-propanol (10 mM) on naturally-occurring Campylobacter was further investigated during incubation of a porcine fecal suspension. Campylobacter concentrations decreased more rapidly (P < 0.05) during incubation of porcine fecal suspensions supplemented with 2-nitro-1-propanol than unsupplemented control suspensions or suspensions supplemented with nitroethane thus reiterating the superior inhibitory effect of 2-nitro-1-propanol.