Inappropriate prescribing contributes to high antibiotic exposure in young children in Australia

Antibiotic exposure increases antimicrobial resistance and has also been associated with long-term harms, including allergies, inflammatory diseases and weight gain. We assessed antibiotic exposure in the first 2 years of life in Australian children, the factors influencing this and its appropriateness. Data from 1201 participants in the MIS BAIR randomized controlled trial were used. Multivariable logistic regression was used to identify factors associated with antibiotic exposure. At 1 and 2 years of age, exposure to at least one course of antibiotics was 43% and 67%, with the highest first antibiotic prescription rate between 9 and 18 months. Amoxicillin was the most frequently used antibiotic (59%), followed by cefalexin (7%). The most common diagnoses for which antibiotics were prescribed were respiratory tract infections from 0 to 6 months of age and otitis media from 6 to 12 months. Factors associated with antibiotic exposure from 0 to 12 months of age were delivery by Caesarean section (adjusted odd-ratio (aOR) 1.5, 95%CI 1.1-1.9), birth in winter (aOR 1.7, 95%CI 1.2-2.4), maternal antibiotic exposure during the last trimester of pregnancy (aOR 1.6, 95%CI 1.1-2.3), cessation of breastfeeding by 6 months of age (aOR 1.5, 95%CI 1.1-2.0) and day-care attendance (aOR 1.4, 95%CI 1.1-1.8). Based on parent-reported questionnaires, 27% of infants were treated in the first year of life for conditions unlikely to need antibiotic treatment. At least two-thirds of children were prescribed antibiotics in the first 2 years of life, and more than a quarter of these exposures may have been unnecessary.