Prevalence of colonization and mitochondrial large subunit rRNA mutation of Pneumocystis jiroveci among Iranian children

BACKGROUND AND OBJECTIVES Pneumocystis jiroveci is an important causative agent of Pneumocystis pneumonia. During childhood, exposure to Pneumocystis occurs and antibody was built in early childhood. The aim of this study was to describe the molecular epidemiology of P. jiroveci in children without any respiratory syndrome and survey the distribution of different mitochondrial large subunit, ribosomal ribonucleic acid (mtLSU- rRNA) genotypes. MATERIALS AND METHODS Mini-bronchoalveolar lavage (mini-BAL) fluids from pediatric patients with no history of lung disorders were obtained during a 14-month period. P. jiroveci colonization was confirmed by immunofluorescence staining, nested PCR and sequencing. Genotypic characterization at the mitochondrial large subunit rRNA gene was performed by direct sequencing. RESULTS Of 172 BAL specimens from patients, with mean age of 4.9 years, the prevalence of P. jiroveci colonization was 3.5% (6 samples). The results of sequencing revealed the two polymorphisms; 85/A; 248/C in 3 cases, and 85/T; 248/C in other cases. One sample also showed a mutation replacement at position 258 (T-to-C change), which was not reported previously. CONCLUSION Colonized person as an environmental reservoir might play an important role in the progression of infection in immunocompromised patients. Diagnosis of the reservoir and genotyping can be essential for the prevention of nosocomial infections.