Pneumocystis jirovecii genotyping: experience in a tertiary-care hospital in Northern Italy.

Respiratory samples from Pneumocystis jirovecii pneumonia (PJP) cases collected at a tertiary-care university hospital in Modena were analyzed for the presence of specific polymorphisms in the mitochondrial large subunit ribosomal RNA (mtLSU-rRNA). Retrospectively, 57 cases were selected in a six-year period and 34 out of the 57 processed BAL samples returned PCR positive results, thus allowing further molecular analysis. The following P.jirovecii genotype distribution was observed: genotype 3 (50%), genotype 2 (23%), genotype 1 (18%), genotypes 1 or 4 (9%). These data add novel insights on P.jirovecii epidemiology, investigating a previously unstudied area of Northern Italy. A peculiar local distribution is highlighted with respect to other areas within the national panorama, thus encouraging further in-depth studies in an attempt to better understand the overall situation concerning P.jirovecii genotype circulation.