Background: It is unclear whether reducing antibiotic prescriptions can reduce rates of resistance once resistance becomes prevalent. We attempted to determine whether reduced antibiotic consumption, which is observed yearly in children during the warm season, is associated with a reduction in antibiotic resistance in pneumococcal acute otitis media (AOM). Methods: Antibiotic prescriptions and resistance were measured prospectively during 1999–2003 in 2 demographically distinct populations: Jewish and Bedouin children (aged <5 years) in southern Israel. Associations were assessed using seasonally clustered logistic regression models. Results: The study included 236,466 prescriptions and 3609 pneumococcal isolates. Prescription rates decreased during the warm months by 36% and 15% in Jewish and Bedouin children, respectively (P<.001 for the season). Among Jewish children, higher resistance rates were observed during the cold than the warm months (P<.001 for each antibiotic). This difference remained significant after adjustment for age, ethnic group, study year, history of antibiotic use, and serotype. The difference was not observed in Bedouin children. Conclusions: Rapid seasonal decline in resistant AOM-causing pneumococci occurred only in Jewish children, among whom a marked prescribing seasonality was noted, and not in Bedouin children, among whom prescription was less seasonal. The rapid seasonal decrease in resistance associated with markedly reduced antibiotic use suggests that drug-resistant pneumococci may pay a fitness cost
