Antibacterial Drugs and the Risk of Community-Associated Methicillin-Resistant Staphylococcus aureus in Children Schneider-Lindner V, Quach C, Hanley JA, Suissa S. Antibacterial drugs and the risk of community-associated methicillin-resistant Staphylococcus aureus in children. Arch Pediatr Adolesc Med. Published online August 1, doi: /archpediatrics Copyright restrictions may apply

Introduction Methicillin-resistant Staphylococcus aureus (MRSA) is common in hospitals and is increasingly reported in the community. This emerging resistant organism generally affects younger and healthier individuals, including children. The association of antibacterial agents with later MRSA diagnoses has been demonstrated for adults, but data on children are lacking. Copyright restrictions may apply

Methods Study Design: Population-based case-control study in children 1 to 19 years of age from the General Practice Research Database, United Kingdom, Participants: Cases were children who had MRSA diagnosed as outpatients; controls were individually matched on age and practice, with the matched case’s diagnosis date as the index date for both. Copyright restrictions may apply

Methods Data Analysis: Antibacterial agents prescribed 180 to 30 days prior to the index date were identified, excluding prescriptions 30 days before the index date to prevent protopathic bias. Using conditional logistic regression, adjusted rate ratios were estimated from the odds ratios of antibacterial exposure in cases compared with controls. Limitations: –Children younger than 1 year were excluded because follow-up time for exposure and covariate information were required. –Asymptomatic colonization could not be distinguished from clinically severe infection. Copyright restrictions may apply

Results We identified 297 cases and 9357 matching controls. 52.5% of cases vs 13.6% of controls had received 1 or more antibacterial drug prescriptions in the 150-day exposure window. Accounting for differences in sex, comorbid conditions, and hospitalizations, this difference translated to a more than 3-fold higher risk of MRSA diagnosis in children with any prior antibacterial drug prescription compared with those without (adjusted rate ratio = 3.5; 95% CI, ). Copyright restrictions may apply

Results Copyright restrictions may apply The MRSA risk increased with increasing numbers of antibacterial prescriptions. Prescriptions, No. Adjusted Rate Ratiofor MRSA Diagnosis

Results The MRSA risk varied with prior exposure to different antibacterial drug classes. Copyright restrictions may apply Association of Different Classes of Antibacterial Drugs with Ca-MRSA Diagnoses in Children, General Practice Research Database, United Kingdom,

Comment The results support efforts to minimize unnecessary antibacterial drug prescribing, particularly of second-line agents, to children in the community. Copyright restrictions may apply

Comment The findings should be confirmed in other data sources. Causality for antibacterial drug prescriptions with subsequent MRSA infections in children remains to be established. Antibacterial use, particularly related to unnecessary prescribing to children, as well as MRSA incidence in the community require ongoing monitoring. Copyright restrictions may apply

Contact Information If you have questions, please contact the corresponding author: –Samy Suissa, PhD, Centre for Clinical Epidemiology, Sir Mortimer B. Davis–Jewish General Hospital, 3755 Côte Ste-Catherine, Ste H4, Montreal, QC H3T 1E2, Canada Funding/Support Dr Schneider-Lindner was the recipient of a fellowship from the Canadian Institutes for Health Research. Copyright restrictions may apply