Doctoral Thesis
Antimicrobial resistance and public health implications of Campylobacter from chicken and pigs
Doctor of Philosophy (PhD), Murdoch University
2023
Abstract
Campylobacter is an important foodborne pathogen listed among the top four causes of gastroenteritis globally. Infections are usually self-limiting but in severe cases, antibiotics are used for treatment. However, resistance (AMR) to critically important antimicrobials is on the rise and continues to threaten public health gains. Therefore, the surveillance of AMR is important for developing interventions by providing information on the presence and prevalence of resistant bacteria. In this thesis, the prevalence, AMR as well as genomic profiles of Campylobacter from poultry meat, chicken caeca and pig faecal matter was studied from Ghana and Australia. The literature review gave a comprehensive overview of Campylobacter at the human-food interface on the African continent. The first experiment, reported prevalence and AMR of Campylobacter from retail chicken meat in wet markets and supermarkets in Accra. High counts were recorded through the direct plating method and a prevalence of 38.3% was recorded from 400 retail chicken. Isolation was by the broth enrichment and direct plating method. The rate of isolation from wet markets was 1.6 times that of supermarkets. Using the disc diffusion method, high resistance to tetracycline, erythromycin and ciprofloxacin was recorded.
The second experiment determined antimicrobial resistance and genomic characterization of Campylobacter from Australia meat chickens. Antibiotic concentrations were prepared on a robotic platform and isolates tested using the broth microdilution technique. We recorded fluoroquinolone resistance of 3.2% to C. coli and 24.4% to C. jejuni. Through whole genome sequencing, 29 and 13 sequence types were detected for C. jejuni and C. coli respectively 7 of which were fluoroquinolone resistant.
In experiment three, an Australia-wide survey of finisher pigs reported a Campylobacter prevalence of 72.7%. Using broth microdilution technique for susceptibility testing, high resistance to azithromycin (64.1%), clindamycin (60.2%), erythromycin (58.3%) and tetracycline (56.9%) were recorded. Ciprofloxacin resistance was recorded at 5.4%. Sequencing revealed 38 known sequence types of C. coli with the majority belonging to 828 clonal complex.
This thesis underscores the need for enforcement of legislation and effective antimicrobial stewardship especially in developing countries like Ghana. In Australia efforts must be made to consolidate gains made while further investigating persistence of fluoroquinolone resistance as well as interclass resistance to macrolides. The use of robotics can further enhance Australia’s AMR surveillance efforts.
Details
- Title
- Antimicrobial resistance and public health implications of Campylobacter from chicken and pigs
- Authors/Creators
- Nikki Owiredu
- Contributors
- Sam Abraham (Supervisor) - Murdoch University, Centre for Biosecurity and One HealthRebecca Abraham (Supervisor) - Murdoch University, Centre for Biosecurity and One HealthHui San Allison (Supervisor)
- Awarding Institution
- Murdoch University; Doctor of Philosophy (PhD)
- Identifiers
- 991005633270107891
- Murdoch Affiliation
- School of Medical, Molecular and Forensic Sciences
- Resource Type
- Doctoral Thesis
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