Molecular epidemiology of Staphylococcus aureus in pediatric cystic fibrosis patients: a single-center study.

INTRODUCTION

Staphylococcus aureus is a key respiratory pathogen in children with cystic fibrosis (CF). This study aimed to evaluate the prevalence and relatedness of spa types of S. aureus respiratory isolates from pediatric CF patients, grouped by age, and to assess their antimicrobial resistance.

METHODS

A total of 165 S. aureus isolated from 82 patients from single-center and diagnosed with cystic fibrosis over a three-year period were analyzed. Molecular typing (spa typing and SCCmec typing) and antimicrobial susceptibility testing were performed.

RESULTS

Sixty-four spa types were identified, including five novel types, and the isolates were assigned to 11 multilocus sequence typing (MLST) clonal complexes, most frequently CC30, CC22, CC97, CC45, and CC15. In 67.1% of patients, only a single spa type was detected. In cases where multiple types were isolated from a single patient, 85.2% of the isolates were not clonally related. Macrolide and lincosamide resistance was common, particularly among adolescents aged 12-18 years, at rates of 67.4% and 60.9%, respectively. Resistance to fluoroquinolones, aminoglycosides, tetracyclines, and co-trimoxazole did not exceed 15%. MRSA was detected in 10.7% of patients and exclusively among those with monoclonal colonization.

CONCLUSION

The finding indicates that S. aureus colonization in pediatric CF patients is highly diverse and primarily individualized, with limited evidence of clonal transmission. Given the high prevalence of macrolide resistance-particularly among adolescents-long-term macrolide therapy should be carefully monitored, with periodic microbiological surveillance to mitigate resistance selection.