Clinical And Molecular Epidemiology Of Invasivestaphylococcus Aureusinfection In Utah Children; Continued Dominance Of Mssa Over Mrsa

Background InvasiveStaphylococcus aureusinfections are a common cause of morbidity and mortality in children. In the early 2000's the proportion of infections due the methicillin-resistantS.aureus(MRSA) increased rapidly. We described the clinical and molecular epidemiology of invasiveS.aureusdisease in a pediatric population. Methods We prospectively identified children in Utah with invasiveS.aureusinfections. Medical records were reviewed to determine diagnosis and clinical characteristics. Isolates were genotyped using multi-locus sequence typing. The presence of genes encoding the Panton-Valentine leukocidin (PVL) was determined using polymerase chain reaction. Results Over a 4-year period between January 2009 and December 2012, we identified 357 children, hospitalized at Primary Children's Hospital, with invasiveS.aureusinfections and isolates available for the study. Methicillin-susceptibleS.aureus(MSSA) caused 79% of disease, while MRSA caused only 21% of disease. Mortality associated with invasiveS.aureusinfection was 3.6%. The most common diagnoses were osteoarticular infections (38%) followed by central line associated blood stream infections (19%) and pneumonia (12%). We identified 41 multi-locus sequence types. The majority of isolates belonged to 6 predominant clonal complexes (CC5, CC8, CC15, CC30, CC45, CC59). PVL was present in a minority (16%) of isolates, of which most were ST8 MRSA. Conclusions MSSA was the primary cause of invasiveS.aureusinfections at our institution throughout the study period. A limited number of predominant strains accounted for the majority of invasive disease. The classic virulence factor PVL was uncommon in MSSA isolates. Further study is needed to improve our understanding ofS.aureusvirulence and disease pathogenesis.