Comparative Analysis of Antibiotic Resistance in Dairy and Swine Farms

Thesis Abstract

Antibiotic resistance (ABR) poses a critical threat to both animal and public health, particularly within livestock production systems where antibiotics are extensively used for therapeutic, prophylactic, and growth-promoting purposes. Despite the growing recognition of ABR as a One Health challenge, comparative analyses between different livestock sectors such as dairy and swine farms remain limited, hindering targeted intervention strategies. This study aims to analyze and compare the prevalence, patterns, and factors influencing antibiotic resistance in bacteria isolated from dairy and swine production environments, thereby contributing to a deeper understanding of sector-specific ABR dynamics. The specific objectives include quantifying antibiotic resistance profiles in bacterial isolates, identifying commonly used antibiotics and practices contributing to resistance, examining genetic determinants of resistance, and assessing farmer knowledge, attitudes, and practices concerning antibiotic use and resistance. Employing a cross-sectional analytical design, the study was conducted across 20 dairy farms and 20 swine farms within a defined geographic region characterized by intensive livestock production. The study population comprised farm personnel, veterinary practitioners, and bacterial isolates from fecal samples collected directly from animals. A sample size of 200 bacterial isolates (100 from each sector) was targeted, using stratified random sampling to ensure representativeness. Data collection involved structured questionnaires administered to farmers and veterinarians regarding antibiotic usage practices, alongside microbiological sampling and processing of fecal specimens. Bacterial isolates, primarily Escherichia coli and Salmonella spp., were characterized using standard microbiological techniques, with antibiotic susceptibility testing performed via the Kirby-Bauer disk diffusion method in alignment with Clinical and Laboratory Standards Institute (CLSI) guidelines. Molecular characterization of resistance genes was conducted through polymerase chain reaction (PCR) assays targeting common resistance determinants such as blaCTX-M, tetA, and sul1. Data analysis employed descriptive statistics for prevalence, chi-square tests for categorical comparisons, and multivariate logistic regression models to identify factors associated with resistant phenotypes. Additionally, hierarchical clustering and principal component analysis (PCA) were used to elucidate patterns among resistance profiles and farm practices. Expected findings indicate significant differences in the prevalence and types of antibiotic-resistant bacteria between dairy and swine farms, with higher resistance levels observed in swine due to more frequent antibiotic use. The study anticipates identifying specific antibiotics, such as tetracyclines and aminoglycosides, as primary drivers of resistance within both sectors, alongside a diverse repertoire of resistance genes with sector-specific distribution. Factors such as farm management practices, antibiotic stewardship, and knowledge levels are hypothesized to significantly influence resistance patterns. The results are expected to reveal correlations between antibiotic usage practices and resistance emergence, providing empirical evidence to inform sector-specific antimicrobial stewardship programs. This research contributes novel insights into the sectoral nuances of antibiotic resistance within livestock production, filling a critical gap in comparative sectoral analyses. By integrating microbiological, molecular, and behavioral data, the study advances the understanding of the drivers and dissemination pathways of antibiotic resistance in animal agriculture. The findings will inform policymakers, veterinarians, and farmers in designing targeted interventions to curb ABR, promote judicious antibiotic use, and strengthen biosecurity measures across livestock sectors. In conclusion, the study recommends enhanced surveillance systems, sector-specific educational initiatives, and stricter regulatory frameworks on antibiotic use, emphasizing the importance of integrated approaches for sustainable livestock production and public health protection.