Genetic diversity of Pneumocystis jirovecii in colonized Cuban infants and toddlers.

Pneumocystis jirovecii is a leading cause of opportunistic infections among immunocompromised patients. The aim of this study was to determine the genetic diversity of P. jirovecii from colonized Cuban infants and toddlers by analysis of four genetic loci: mitochondrial large subunit (mtLSU) rRNA, cytochrome b (CYB), superoxide dismutase (SOD) and ß-tubulin (ß-tub). We determined the multilocus profiles based on concatenated genotype data (multilocus genotype; MLG) and nucleotide sequences (multilocus sequence analysis; MLSA) respectively, calculated the discriminatory power of each analysis, and investigated possible associations with demographic and clinical data. Sixteen of 51 PCR-positive nasopharyngeal swab specimens (years 2010-2013) with high P. jirovecii load were selected for downstream analysis. In mixed allelic profiles all genotypes/nucleotide sequence patterns were considered separately. All samples could be genotyped based on mtLSU, CYB and ß-tub locus. However, the SOD locus could be successfully amplified in only 7/16 (44%) specimens. Eight different P. jirovecii MLGs were identified among the 16 cases and eight samples presented identical MLG (MLG 1). Seventeen MLSA profiles were distinguished. No statistical association between genotypes or MLGs and demographic or clinical data could be identified. For MLSA the higher discriminatory power (S=0.976) was observed. The combination of mtLSU, CYB and ß-tub loci proved to be useful for molecular epidemiology studies of P. jirovecii. A total of 17 different MLSA profiles observed in 16 specimens indicated high genetic variability of P. jirovecii circulating in colonized Cuban infants and toddlers.

Prevalence and genotype distribution of Pneumocystis jirovecii in Cuban infants and toddlers with whooping cough.

This study describes the prevalence and genotype distribution of Pneumocystis jirovecii obtained from nasopharyngeal (NP) swabs from immunocompetent Cuban infants and toddlers with whooping cough (WC). A total of 163 NP swabs from 163 young Cuban children with WC who were admitted to the respiratory care units at two pediatric centers were studied. The prevalence of the organism was determined by a quantitative PCR (qPCR) assay targeting the P. jirovecii mitochondrial large subunit (mtLSU) rRNA gene. Genotypes were identified by direct sequencing of mtLSU ribosomal DNA (rDNA) and restriction fragment length polymorphism (RFLP) analysis of the dihydropteroate synthase (DHPS) gene amplicons. qPCR detected P. jirovecii DNA in 48/163 (29.4%) samples. mtLSU rDNA sequence analysis revealed the presence of three different genotypes in the population. Genotype 2 was most common (48%), followed in prevalence by genotypes 1 (23%) and 3 (19%); mixed-genotype infections were seen in 10% of the cases. RFLP analysis of DHPS PCR products revealed four genotypes, 18% of which were associated with resistance to sulfa drugs. Only contact with coughers (prevalence ratio [PR], 3.51 [95% confidence interval {CI}, 1.79 to 6.87]; P = 0.000) and exposure to tobacco smoke (PR, 1.82 [95% CI, 1.14 to 2.92]; P = 0.009) were statistically associated with being colonized by P. jirovecii. The prevalence of P. jirovecii in infants and toddlers with WC and the genotyping results provide evidence that this population represents a potential reservoir and transmission source of P. jirovecii.