Molecular epidemiology and pathogenicity analysis of community-acquired MRSA in Japanese children with a severe or...

Area of Science:

• Infectious Diseases
• Microbiology
• Pediatrics

Background:

• Reports of severe infections caused by Panton-Valentine leukocidin (PVL)-positive community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) are increasing globally.
• Pediatric infections caused by CA-MRSA are rising worldwide, affecting children with and without known risk factors.
• Emerging threats include PVL-producing USA300-related clones and ST22-PT clones, which also produce toxic shock syndrome toxin-1 (TSST-1).

Purpose of the Study:

• To investigate the characteristics of severe or recurrent MRSA infections in pediatric patients.
• To identify the molecular profiles of CA-MRSA isolates causing severe infections in children.
• To assess the risk posed by specific CA-MRSA clones in pediatric healthcare settings.

Main Methods:

• Retrospective analysis of 10 pediatric patients with severe or recurrent MRSA infections treated between 2021 and 2024.
• Molecular analysis of MRSA isolates, including SCCmec typing, PVL and TSST-1 detection.
• Multilocus sequence typing (MLST) to determine sequence types (STs) and identify specific clones like USA300 variants and ST22-PT.

Main Results:

• CA-MRSA accounted for the majority of MRSA infections in the studied pediatric cohort.
• Severe cases were frequently caused by PVL-positive (50%) or TSST-1-positive (30%) strains.
• Sixty percent of isolates belonged to ST8 (USA300-related variants), and one isolate was identified as ST22-PT.

Conclusions:

• CA-MRSA, particularly PVL or TSST-1 positive strains, is a significant cause of severe pediatric infections.
• CA-MRSA poses a risk in healthcare settings, especially for immunocompromised children.
• Continued molecular surveillance is crucial for effective treatment and infection control of pediatric MRSA infections, particularly concerning USA300-related and ST22-PT clones.