Epidemiologic and Molecular Characteristics of Staphylococcus aureus Strains Isolated From Hospitalized Pediatric Patients.

Abstract

We aimed to determine molecular characteristics of Staphylococcus aureus isolates cultured from hospitalized pediatric patients. All accessible S. aureus isolates cultured from hospitalized pediatric patients were analyzed for staphylococcal cassette chromosome mec (SCCmec) types, Panton-Valentine Leukocidin (PVL) encoding genes and antibiotic resistance patterns. A total of 132 S. aureus isolates, 102 methicillin-susceptible S. aureus (MSSA) (81.8%), 30 methicillin-resistant S. aureus (MRSA) (18.2%) were included in the study. Sixty of 132 (45.5%) S. aureus isolates were cultured from skin and soft tissue infections (SSTIs), 50 (37.9%) from bloodstream infections, 11 (8.3%) from bone infections and 11 (8.3%) from other sterile sites. Fifty-three of 102 (52%) MSSA isolates were cultured from SSTI, 35 (34.3%) from bloodstream infections, 7 (6.9%) from bone infections and 7 (6.9%) from other sterile sites (P = 0.083). Fifteen MRSA isolates (50%) were cultured from blood culture, 7 from (23.3%) SSTI, 4 (13.3%) from bone infections and 4 from (13.3%) other sterile sites. Nine PVL gene harboring S. aureus isolates were isolated from SSTI (75%), 2 from blood culture (16.7%) and 1 from other sterile site (8.3%). Three MRSA (6.7%) isolates were found to be positive for SCCmec type III and 16 MRSA isolates (53.3%) were found to be positive for SCCmec type IV. Three MRSA isolates harboring SCCmec type III was isolated from blood culture, 11 of 16 MRSA isolates harboring SCCmec type IV was isolated from blood culture, 3 isolates were isolated from bone infections and 2 isolates were isolated from SSTI (P < 0.001). Five of 72 (6.9%) hospital-acquired S. aureus isolates and 7 of 60 (11.7%) community-acquired S. aureus isolates were PVL gene positive. Twenty-two of 72 (30.6%) hospital-acquired S. aureus infections and 8 of 60 (13.3%) community-acquired S. aureus isolates were MRSA (P = 0.015). All of the 3 SCCmec III harboring MRSA isolates and 11 of 16 SCCmec IV carrying MRSA isolates were hospital acquired. Hospitalization in the past 1 year was found to increase MRSA infections 3.95 times (P = 0.038, 95% confidence interval: 1.078-14.48). As distribution of virulence genes differs among S. aureus isolates from different regions, it is necessary to monitor the emergence of genes encoding PVL, SCCmec in both MRSA and MSSA throughout the world. Our results show a high prevalence of PVL in community-onset S. aureus infections in children. SCCmec type IV was more commonly isolated in hospital-acquired MRSA isolates, and PVL gene was more commonly isolated in community-acquired S. aureus infections.