Abstract
Pneumocystis jirovecii is an important opportunistic pathogen that causes severe pneumonia in immunocompromised patients. The aim of the present study was to investigate the genetic diversity of P. jirovecii strains by direct sequencing and analysis of the Upstream Conserved Sequence (UCS) region, mitochondrial large-subunit (mtLSU) rRNA and dihydrofolate reductase (DHFR) genes. We identified the polymorphisms in P. jirovecii strains of 15 immunocompromised patients, as well as detecting a new tandem repeat of 5 nucleotides in UCS region. The following three different types of repeat unit were found: type a GCCCA; type b GCCCT; and type c GCCTT. In addition, we identified the repeat unit which consisted of 10 nucleotides and three different patterns of UCS repeats with 3 and 4 repeats, i.e., 1, 2, 3 (86.7%), 1, 2, 3, 3 (6.6%) and a new genotype 2, 2, 3, 3 (6.6%). The polymorphism in the mtLSUrRNA gene was seen primarily at position 85 where we detected three different genotypes. Genotype 3 and genotype 2 were the most abundant with frequencies of 53.3% and 40%, respectively. With regard to the DHFR gene, only two (20%) patients had nucleotide substitution in position 312. In conclusion, the multilocus analysis facilitated the typing of P. jirovecii strains and proved the important genetic biodiversity of this fungus.
Declaration of interest : The authors report no conflicts of interest. The authors alone are responsible for the content and the writing of the paper.
This study was carried out with the financial support of the Ministry of Higher Education and Scientific Research of Tunisia.
This paper was first published online on Early Online on 4 December 2012.