Comparative Analysis of Antibiotic Resistance in Bovine and Swine Pathogens

Thesis Abstract

Antibiotic resistance among bacterial pathogens in livestock poses a significant threat to animal health, public health, and food safety, threatening effective disease control and increasing economic losses in the agricultural sector. Despite extensive research on antimicrobial resistance (AMR), comparative data elucidating the extent, patterns, and determinants of resistance in pathogens isolated from bovine and swine populations remain limited, particularly in regions with intensive farming practices. This study seeks to address this gap by conducting a comprehensive comparative analysis of antibiotic resistance profiles in bacterial pathogens isolated from bovine and swine farms, aiming to enhance understanding of interspecies variations and underlying factors influencing resistance development. The primary objective of this research is to determine and compare the prevalence and patterns of antibiotic resistance in bacterial pathogens from bovine and swine specimens; to identify the resistance determinants through molecular profiling; and to assess farm management and antimicrobial usage practices associated with resistance emergence. Specific objectives include quantifying resistance rates to commonly used antibiotics such as tetracyclines, ?-lactams, aminoglycosides, and fluoroquinolones; characterizing resistance genes via polymerase chain reaction (PCR) and sequencing; and evaluating correlations between farm practices and resistance levels using multivariate statistical methods. Employing a cross-sectional research design within a positivist paradigm, the study sampled a total of 200 farms—100 bovine and 100 swine farms—selected through stratified random sampling across the region's livestock-dense counties. Bacterial isolates, primarily Escherichia coli, Salmonella spp., and Staphylococcus aureus, were collected from animals showing clinical signs or deemed at risk during routine health assessments. A total of 600 isolates (300 from each species) underwent antimicrobial susceptibility testing following Clinical and Laboratory Standards Institute (CLSI) guidelines using the disk diffusion method. Molecular characterization of resistance genes, including bla_TEM, tetA, aadA, and gyrA mutations, was performed using PCR and sequencing techniques. Data on farm management, antimicrobial usage, and biosecurity practices were collected through structured questionnaires and farm records. The analysis involved descriptive statistics to establish prevalence rates, chi-square tests to examine resistance differences between species, and logistic regression models to identify factors associated with resistance acquisition. Molecular data were analyzed through qualitative assessment of gene presence and sequence variation. Expected findings include higher resistance prevalence in swine pathogens to tetracyclines and aminoglycosides compared to bovine isolates, with specific resistance genes correlating with phenotypic resistance. The study anticipates identifying key farm management practices—such as blanket antimicrobial use, inadequate biosecurity, and high-frequency treatment—as significant contributors to resistance development. This research is poised to make a substantive contribution to the existing body of knowledge by providing a detailed comparative assessment of antimicrobial resistance patterns in bovine and swine pathogens, integrating phenotypic resistance data with molecular insights. It will elucidate species-specific resistance trends and associated farm factors, informing targeted antimicrobial stewardship policies and farm management strategies. The findings are expected to support policymakers and veterinarians in designing evidence-based interventions to curb the escalation of AMR in livestock production systems. In conclusion, this study underscores the need for integrated surveillance and judicious antimicrobial use to mitigate resistance proliferation across livestock sectors. Recommendations include the implementation of farm-level antimicrobial stewardship programs, enhanced biosecurity measures, and regular resistance monitoring. Future research should focus on longitudinal studies to assess temporal resistance trends and evaluate the effectiveness of intervention strategies in reducing antimicrobial resistance in livestock pathogens.