The hypothesis of the present study is that quantitative and qualitative oral microflora alterations and changes in antibiotic susceptibility among oral commensal microflora will occur following a single dose administration of amoxicillin.

A total of 33 healthy volunteers, 16 males and 17 females, will be included. Written informed consent will be obtained from all participants.

Subjects will be excluded if they have taken antibiotics within the previous three months, are pregnant, breast-feeding or allergic against penicillin.

The participants will be given a single dose of 2 g amoxicillin. Saliva samples will be collected before administration of antibiotics (day 1) and on day 2, 5, 10, 17 and 24. Un-stimulated saliva will be accumulated in a plastic container. Concentration of amoxicillin in saliva will be measured on day 1, 2 and 5. Samples will be used for the determination of antibiotic concentration. Analyses of the sensitivities to amoxicillin and some other clinically relevant antibiotic compounds will also be performed.

Inclusion Criteria:

• Written informed consent
• Healthy
• Age 18-45
• Understands the study procedure and speaks Swedish and/or English

Exclusion Criteria:

• Treatment with antibiotics within the previous three months
• Pregnant
• Breast-feeding
• Allergic against penicillin
• Concomitantly participate in another medical product study
• Treatment with any kind of medication, health food preparations or probiotics