Molecular characterization of Staphylococcus aureus isolated from hospital acquired sepsis in pediatrics, relation to antibiotics, resistance and virulence genes.

Abstract

The objective of this study was to determine the prevalence of antibiotic resistance genes mecA, vanA, B, C and virulence genes Panton-Valentine Leucocidin (PVL) and fibronectin-binding protein (fnBPA) among S. aureus isolates from hospital-acquired sepsis from pediatric intensive care units. The study was a retrospective cross-sectional study, including 250 unique isolates of S. aureus obtained from pediatric patients with hospital-acquired sepsis. The isolates were subjected to study of antibiotic susceptibility by disc diffusion method and molecular analysis of antibiotic resistance genes and certain virulence genes (PVL and fnBPA genes). Methicillin resistant S. aureus represented 178 (71%) of the isolated S. aureus and reduced susceptibility to vancomycin was detected by minimum inhibitory concentration in 39 (22%) isolates. It was found that there was a strong association between the MRSA strains and resistance to some antibiotics, devices association (p<0.001) and patient outcomes (p=0.003). There was a significant association between reduced vancomycin susceptibility (p=0.010), the presence of a central line catheter (p=0.000) and fnBPA gene (p<0.001) and mortality rate. The present study highlights that major S. aureus strains isolated from sepsis in pediatric patients were methicillin resistant with a substantial proportion of reduced susceptibility to vancomycin. Although none of the isolates had van genes responsible for vancomycin resistance, this finding warrants a considerable attention for study as it was a risk factor for mortality in those patients. The virulence genes fibronectin-binding protein and Panton-Valentine Leucocidin were not uncommon in S. aureus.