Antimicrobial Resistance Genes (ARGs) Monitoring and Gut Microbiota Profiling in Honey Bees from an Intensive Livestock Farming Area in Northwestern Italy

Antimicrobial resistance (AMR) is a growing global concern, exacerbated by the overuse of antibiotics in livestock farming. Honey bees (Apis mellifera), widely used as bioindicators of environmental contamination, may also serve as sentinels for monitoring the environmental spread of antibiotic resistance genes (ARGs). This study investigated the presence of ARGs and the gut microbiota composition of honey bees sampled from 11 apiaries located in a region of Northwestern Italy characterized by intensive livestock farming. PCR and Sanger sequencing analyses revealed a widespread presence of tetracycline resistance genes—particularly tetB and tetC—as well as occasional detection of blaTEM, qnrB, and int1 genes. tetB and tetC were also identified in three bacterial colonies isolated from bee guts, notably in Hafnia spp. 16S rRNA gene sequencing of the gut microbiota revealed dominance of genera such as Bartonella, Snodgrassella, Gilliamella, Bombilactobacillus, and Lactobacillus. Some samples showed shifts in the microbial diversity. The findings confirm the potential of honey bees as bioindicators for environmental AMR surveillance and underscore the need for further research to elucidate correlations between ARG presence and microbial community structure in honey bees from various ecological contexts.