Global consumption of oral antibiotics (AB) is increasing, with 80% of all prescriptions in Europe stemming from primary care, mostly against respiratory tract infections. Adequate intake behavior (i.e. adherence) to oral AB is vital to prevent therapeutic failure, to reduce the risk of microbial resistance, to reduce health care consumption, medication waste and environmental pollution. However, non-adherence among oral AB users reaches rates of 21%-38% during an AB treatment course. To improve medication adherence, understanding patient barriers to treatment is crucial. Based on barriers identified in a systematic literature search, a self-report questionnaire called "BIOTICA" has been developed by the research team to assess medication adherence barriers to oral AB. The purpose of the BIOTICA-questionnaire is to detect individual barriers that prevent the optimal intake of oral AB and thus, lead to inadequate adherence or persistence to the regimen. A study is now needed to establish construct validity (also called criterion, convergent or concurrent validity) that is, to generate evidence that the questionnaire measures what it is intended to. Thus, the instrument under investigation (i.e. BIOTICA-questionnaire) will be distributed at the same time as the targeted attribute (i.e. adherence to oral AB) will be electronically monitored in the general population. The correlation between the two measurements will be analyzed.