European study on Pneumocystis jirovecii short tandem repeats genotyping reveals wide population diversity with geographic specificities

• Published in: Journal de mycologie médicale 2016-06, Vol.26 (2), p.e5-e6
• Main Authors: Alanio, A., Gits-Muselli, M., Calderon, E., Di Cave, D., Dupont, D., Hamprecht, A., Hauser, P., Helweg-Larsen, J., Kicia, M., Lagrou, K., Lengerova, M., Matos, O., Melchers, W.
• Format: Article
• Language: English
• Subjects: Pneumocystis
• ISSN: 1156-5233; 1773-0449
• DOI: 10.1016/j.mycmed.2016.04.017

Pneumocystis jirovecii is a human specific uncultivable ascomycetous fungus, for which the reservoir is immunocompetent human individuals. Immunocompromised patients are at risk of developing pneumocystis pneumonia (PCP) when exposed to P.jirovecii through their immediate environment. A recently described short tandem repeat (STR) typing strategy was applied to a population of patients from Paris and found a high diversity of genotypes (Gts) between the patients, but identical Gts reflecting putative interhuman nosocomial transmission [1]. In contrast, another genotyping study using a different STR set described a limited global population of P.jirovecii testing isolates recovered from Africa (n=13), USA (n=49) and Europe (n=29) [2]. Our objective is to determine the distribution of P.jirovecii STR genotypes across European hospitals. We investigated a collection of 355 P.jirovecii microscopy or PCR positive respiratory samples recovered from 355 PCP patients in 12 European countries [France (n=5), Belgium, The Netherlands, Denmark, Germany, UK, Poland, Czech republic, Switzerland, Italy, Spain, and Portugal]. STR typing was performed as previously described [1]. Amplification failure occurred in 32% of the samples, likely a result of insufficient P.jirovecii DNA. Therefore, 242 samples (median: 17 per center (8–24)) were further analyzed. Mixtures of STR markers >1 allele for ≥ 1 locus) were detected in 66.7% [range: 36.4%–90.9%] of the samples, with a trend towards a lower proportion of mixtures in France-centre 2 and Belgium. The distribution of alleles in all six markers was significantly different according to the countries in STRPj_138 (p=0.0002), STRPj_278 (p=0.0085), and STRPj_279 (p=0.0069). Genotyping was analyzed only in samples harboring one allele/locus (n=87) or several alleles for one locus only (n=56). This provided 200 analyzable combinations corresponding to 143 Gts. Of them, 123 were found only in one country, 16 in two, 2 in three and one in 4 and 5 countries. Nine Gts were found more than once in a given country. Gt123 was significantly associated with France (14/15, p=0.0007) and Gt132 with Belgium (5/5, p