Pneumocystis jirovecii Diversity in Réunion, an Overseas French Island in Indian Ocean

Atovaquone exposure and Pneumocystis jirovecii cytochrome b mutations: French data and review of the literature

Pneumocystis jirovecii is a transmissible fungus responsible for severe pneumonia (Pneumocystis pneumonia [PCP]) in immunocompromised patients. Missense mutations due to atovaquone selective pressure have been identified on cytochrome b (CYB) gene of P. jirovecii. It was recently shown that atovaquone prophylaxis can lead to the selection of specific P. jirovecii CYB mutants potentially resistant to atovaquone among organ transplant recipients. In this context, our objectives were to provide data on P. jirovecii CYB mutants and the putative selective pressure exerted by atovaquone on P. jirovecii organisms in France. A total of 123 patients (124 P. jirovecii specimens) from four metropolitan hospitals and two overseas hospitals were retrospectively enrolled. Fourteen patients had prior exposure to atovaquone, whereas 109 patients did not at the time of P. jirovecii detection. A 638 base-pair fragment of the CYB gene of P. jirovecii was amplified and sequenced. A total of 10 single nucleotide polymorphisms (SNPs) were identified. Both missense mutations C431T (Ala144Val) and C823T (Leu275Phe), located at the Qo active site of the enzyme, were significantly associated with prior atovaquone exposure, these mutations being conversely incidental in the absence of prior atovaquone exposure (P < 0.001). Considering that the aforementioned hospitals may be representative of the national territory, these findings suggest that the overall presence of P. jirovecii CYB mutants remains low in France.

Genetic Polymorphisms of Pneumocystis jirovecii in HIV-Positive and HIV-Negative Patients in Northern China

Pneumocystis jirovecii is an opportunistic fungus that can cause severe and potentially fatal Pneumocystis pneumonia (PCP) in immunodeficient patients. In this study, we investigated the genetic polymorphisms of P. jirovecii at eight different loci, including six nuclear genes (ITS, 26S rRNA, sod, dhps, dhfr and β-Tub) and two mitochondrial genes (mtLSU-rRNA and cyb) in three PCP cases, including two patients with HIV infection and one without HIV infection in Shanxi Province, P.R. China. The gene targets were amplified by PCR followed by sequencing of plasmid clones. The HIV-negative patient showed a coinfection with two genotypes of P. jirovecii at six of the eight loci sequenced. Of the two HIV-positive patients, one showed a coinfection with two genotypes of P. jirovecii at the same two of the six loci as in the HIV-negative patient, while the other showed a single infection at all eight loci sequenced. None of the three drug target genes (dhfr, dhps and cyb) showed mutations known to be potentially associated with drug resistance. This is the first report of genetic polymorphisms of P. jirovecii in PCP patients in Shanxi Province, China. Our findings expand our understanding of the genetic diversity of P. jirovecii in China.

The shift from pulmonary colonization to Pneumocystis pneumonia

Pulmonary specimen pairs from five patients who presented with pulmonary colonization and later developed Pneumocystis Pneumonia (PcP) were retrospectively examined for P. jirovecii genotyping. A match of genotypes in pulmonary specimen pairs of three patients was observed, whereas a partial match and a mismatch were observed in the fourth and fifth patients, respectively. The genotyping results suggest that the colonization state can differ from PcP but can also represent the incubation period of PcP. Clinicians should not systematically rule out the treatment of putative colonized patients and should at least discuss the initiation of prophylaxis on a case-by-case basis.