Trends of Methicillin-Resistant Staphylococcus Aureus Infections among Thai Pediatric Patients

Background While reductions in methicillin-resistant Staphylococcus aureus (MRSA) infections have been reported, vancomycin prescription rates have remained high. Objectives We aimed to update trends in pediatric prevalence and antibiotic susceptibilities of MRSA infections. Methods We conducted a retrospective study in patients aged S. aureus infections during 2016-2022 at a Thai tertiary-care hospital. MRSA was defined when resistant to cefoxitin or oxacillin MIC of >4 µg/mL. Patients with MRSA infections and their first isolates were classified into HA-MRSA or CA-MRSA based on surveillance definitions. Antibiotic susceptibilities were tested using the VITEK 2XL automated system and disk diffusion. The annual prevalence of MRSA patients was estimated and compared with Chi-Square for trend. Results Among 1,059 children with S. aureus infections, MRSA was identified in 82 patients (7.7%; 95%CI 6.2-9.6), consisting of 65 healthcare-associated MRSA and 17 community-associated MRSA. Our trend in MRSA prevalence has exhibited significantly downward (p =0.003). MRSA isolates were fully susceptible to vancomycin, linezolid, and tigecycline, with high susceptibilities to fosfomycin and fusidic acid (>90%), lower to trimethoprim-sulfamethoxazole (77%) and tetracycline (48%), and the least to clindamycin (18%). Conclusions A declining trend and low prevalence of MRSA infections were observed among pediatric patients, justifying the cautious use of vancomycin as empirical therapy for patients without the risk of MRSA acquisition. MRSA isolates remained highly susceptible to most current antibiotics, which further supports the effectiveness of these treatments against MRSA.