Pathogenic Role and Antibiotic Resistance of Methicillin-Resistant Staphylococcus aureus (MRSA) Strains Causing Severe Community-Acquired Pneumonia in Vietnamese Children

HIGHLIGHTS: What are the main findings? Methicillin-resistant Staphylococcus aureus (MRSA) plays a greatly important role as the second leading cause of severe community-acquired pneumonia (CAP) in Vietnamese children; All isolates of MRSA are resistant to many antibiotics and sensitive to vancomycin and linezolid. What are the implications of the main finding? MRSA agents should be considered for empiric antibiotic therapy for severe CAP in children because of the role of MRSA in the disease; It is necessary to have a rational antibiotic use strategy to prevent vancomycin resistance in the future. ABSTRACT: In recent years, the pathogenic role and antibiotic resistance of methicillin-resistant Staphylococcus aureus (MRSA) strains causing severe community-acquired pneumonia (CAP) have received increasing attention in clinical practice. The aim of this study was to determine the rate of isolates of MRSA strains causing severe CAP in children and to assess their level of antibiotic resistance. The study design was cross-sectional. Children with severe CAP were sampled by nasopharyngeal aspiration for the culture, isolation, and identification of MRSA. Antimicrobial susceptibility testing was performed using the gradient diffusion method to determine the minimum inhibitory concentration (MIC) of antibiotics. Results: MRSA was identified as the second leading cause of severe CAP in Vietnamese children. The rate of isolates of S. aureus was 41/239 (17.5%), of which most were MRSA, at 32/41 (78.0%). MRSA strains were completely non-susceptible to penicillin (100%), more resistant to clindamycin and erythromycin, less sensitive to ciprofloxacin and levofloxacin, and fully susceptible to vancomycin and linezolid, with a 32-fold decreased MIC(90) for vancomycin (0.5 mg/L) and a 2-fold decreased MIC(90) for linezolid (4 mg/L). Therefore, vancomycin and linezolid may be appropriate options for severe CAP identified by MRSA.