Ecological consequences of low ampicillin concentrations on an ex-vivo biofilm model of the human oral microbiome

Antibiotics at low concentration can favor processes such as biofilm formation, virulence and antibiotic resistance. This can be of high relevance in microbial communities like the oral microbiome, where commensals and pathogens share a common habitat and where the abundance of antibiotic resistance genes surpasses the abundance in the gut. Here, we used an ex vivo model of human oral biofilms to investigate the impact of ampicillin on biofilm viability. Further, the ecological impact on the microbiome and resistomes was investigated using shotgun metagenomics. To our knowledge, this is the first report on antibiotic effects on oral microbial communities using an ex-vivo human microbiome model combining biofilms and shotgun metagenomics. Overall, the results highlight the potential of using the model to further our understanding of ecological and evolutionary forces driving antimicrobial resistance in oral microbiomes.