Show simple item record

dc.contributor.advisorAteba, C.N.
dc.contributor.advisorSethebe, P.N.
dc.contributor.authorDlamini, Sicelo Beauty
dc.date.accessioned2021-10-20T14:04:28Z
dc.date.available2021-10-20T14:04:28Z
dc.date.issued2016
dc.identifier.urihttp://hdl.handle.net/10394/37608
dc.descriptionMSc (Biology), North-West University, Mafikeng Campusen_US
dc.description.abstractSalmonella species are currently one of the most widespread foodborne pathogens that claim millions of lives yearly nationwide and therefore they pose severe challenges in humans in developing as well as developed countries. In addition, Salmonella infections are difficult to treat due to the ·emergence and wide spread distribution of antibiotic resistant strains. Treatment failures amplify the need to explore the virulence capabilities of other antibacterial agents such as bacteriophages to serve as alternative antimicrobial agents, especially in resolving the war against resistant bacteria strains. The aim of this study was to isolate, characterise and determine the virulence capabilities of Salmonella species and Salmonella specific bacteriophages from cattle faeces and raw beef obtained from some supermarkets and butcheries in the North West Province, South Africa against environmental antibiotic resistant isolates. A total of 300 presumptive Salmonella isolates were isolated from 160 samples (cattle faeces and raw beef) using Salmonella Shigella agar. Typical pale yellow colonies with black spots on their centres were subjected to both preliminary and confirmatory tests specific for Salmonella species. The antibiotic resistance profiles of the Salmonella strains were determined against a panel of 12 antimicrobial agents. Multiple antibiotic resistance phenotypes and cluster analysis of antibiotic resistance inhibition zone diameter data was used to determine the phenotypic relationship of isolates from different sources. PCR assays were used to determine the pathogenicity of the isolates in order to assess their impact on consumers. Genetic similarities among isolates from different sampling stations and/or sources were assessed by determining the restriction fragment length polymorphic (RFLP) patterns of the 16S rRNA gene fragments amplified from isolates in the study. Furthermore, morphological characterisation of Salmonella specific bacteriophages was achieved using the double agar layer technique and electron microscopy. The findings of the study suggest a high presence 140 (46%) of Salmonella species in both cattle faeces and raw beef obtained from the different locations. All the isolates were Gram negative rods while a significantly large proportion 291 (97%) were oxidase negative and only 12 (4%) of the isolates produced H2S. Eight (34.8%) representative isolates were identified as Salmonella species. Of the 300 presumptive isolates a large proportion 159 (53%) were positive for Salmonella based on agglutination with the polyvalent O antiserum and belonged to groups A-G, while 185 (61.7%) were positive for the polyvalent H antiserum. Salmonella species specific 16S rRNA PCR analysis indicated that 128 (42 .7%) were positively identified. Despite the fact that only a small proportion 60 (20%) of the isolates were confirmed as Salmonella species based on the presence of the f/iC gene sequence while 80 (26.7%) had the f/iB gene fragment. Large proportions (62.4% to 94.3%) of the isolates from both cattle faeces and beef samples were most often resistant to Erythromycin, Rifampicin, Penicillin, Ampicillin and Cephalexin. On the contrary, these isolates showed very little resistance (4.3% to 37.9%) against Cefixime, Nalidixic Acid, Gentamicin, Ciprofloxacin, Tetracycline, Norfloxacin and Chloramphenicol. MAR phenotypes E-RP-PG-CFXM, AP-E-RP-PGV CFXM, RP-PG-CFXM, AP-CFM-E-RP-PG-CFXM, T-E-RP-PG-CFXM and AP-CFM-T-ERP- PG-CFXM were dominant among these isolates. On the other hand, phenotypes AP-CFM-NA-CIP-NOR-E-RP-PG, E-RP-PG-CFXM and T-E-RP-PG-CFXM were predominant among isolates obtained from Rustenburg. Despite the fact that phenotype AP-CFM-T-E-RP-PG-CFXM was observed only in 1 isolate obtained from Mafikeng, a cause for concern is that this isolate was resistant to 7 of the 12 antibiotics tested. In addition the AP-CFM-NA-CIP-NOR-E-RP-PG was not only dominant among isolates from Rustenburg but the isolates were resistant to eight different antimicrobial agents. Two major clusters (cluster 1 and cluster 2) that contained four sub-clusters (1A, 1 B, 2A and 2B) were obtained. Generally three sub-clusters (1A, 1 B and 2A) were mixed since they had isolates from almost all the different sites sampled. Large proportions 38 (27.1%) and 46 (30.7%) were positive for the spvC and invA virulence genes respectively. RFLP patterns of 16S rRNA gene fragments indicated that the band sizes ranged from 50 bp and 572 bp and from 50 bp to 300 bp for EcoRI and Haelll respectively. The great similarities in the antibiotic resistance profiles of Salmonella isolates from the different locations indicated that isolates share similarly antibiotic exposure histories. In addition, the similarities in the RFLP patterns of 16S rRNA gene fragments also revealed that the data may be of great epidemiological importance and therefore be very useful in identifying the source of contamination.en_US
dc.language.isoenen_US
dc.publisherNorth-West University (South Africa)en_US
dc.titleMolecular characterization of Salmonella and Salmonella specific bacteriophages from cattle and beef in the North West Province South Africaen_US
dc.typeThesisen_US
dc.description.thesistypeMastersen_US
dc.contributor.researchID16528026 - Ateba, Collins Njie (Supervisor)


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record