280 COMPARISON OF THE DRUG-SUSCEPTIBILITY PROFILE OF STAPHYLOCOCCUS AUREUS AMONG THE ADULT AND PEDIATRIC POPULATIONS, 2001-2006

Drug-susceptibility profile of Staphylococcus aureus is changing rapidly. Comparative data on drug susceptibility patterns of S. aureus in adult and pediatric population are scant.ObjectiveTo compare the drug-susceptibility profile of S. aureus in the adult and pediatric population hospitalized at the University of California, Irvine Medical Center (UCIMC).MethodsWe analyzed drug susceptibility of all patient isolates of S. aureus recovered from various clinical sources for patients hospitalized at UCIMC between January 2001 and July 2006.ResultsDrug susceptibility of 2,268 patient isolates was reviewed and compared for the pediatric (0-18 years old) and the adult (> 18 years old) population (see Table). Adults were more likely to have methicillin-resistant S. aureus (MRSA) isolates compared with the pediatric population for both periods (2001-2003 vs 2004-2006). Clindamycin resistance increased between the two periods, especially for the pediatric population (p < .05). When comparing MRSA and MSSA susceptibility profiles, MRSA isolates were more likely to be resistant to multiple antibiotics (p < .01). Of 832 MRSA, 96% were Erythro-R and 54% were Clinda-R, whereas for 1,436 MSSA isolates, 25% were Erthro-R and 9% were Clinda-R. D-test was performed on all isolates starting August 6, 2004. During this period, of 322 isolates (from all age groups) that tested Erythro-R and Clinda-S initially, 135 (42%) had inducible clindamycin resistance. For the pediatric population, D-test was positive for 26 (37%) of 71 Erythro-R isolates that initially tested Erythro-R and Clinda-S.ConclusionsAt our center, the drugsusceptibility pattern of S. aureus is different in adult and pediatric populations and has changed over time. A significant proportion of the Erythro-R S. aureus has inducible clindamcycin resistance. Further analysis will include review of susceptibility profiles according to the specimen type and mode of transmission of S. aureus (community vs health care associated).