A population study of first exposure to community antibacterials in children and the suitability of routine urine samples for study of the acquisition of drug resistance.

The study objectives were to measure time from birth to first exposure to antibacterials in children and compare the characteristics of children who submit urine samples with the general population. Antibacterials were dispensed to 63% of children within 1 year of birth, increasing to 75% within 2 years after birth. Boys had earlier exposure to antibacterials than girls. Children submitting urine samples were more likely to be socio-economically deprived, have prior exposure to antibacterials and have prior hospital admission. In conclusion, urine samples are unsuitable for a prospective cohort study of the relationship between antibacterial exposure and resistance in children.