A randomised, open labelled study design is selected in order to determine the emergence and persistence of antibiotic resistant bacteria in humans and on the composition of the indigenous microbiotas at various body sites. These will involve the administration to volunteers of minocycline and amoxicillin- a control group will receive a placebo. Microbiology of the skin, saliva, faecal, skin and nasal micro flora, safety and adverse events, vital signs, will be evaluated. The objectives of metagenomic analysis are: