Objectives Recent studies suggest that various tumour types can be colonized by different microorganisms, but data on unusual opportunistic fungus – Pneumocystis jirovecii – remain scarce. Lung cancer patients are considered one of the risk groups for its infection. Since P. jirovecii tends to distribute focally within the lungs, this study aimed to determine whether it can be detected in lung tumour tissue. Methods Fragments of neoplastic tissue (NPL), normal adjacent tissue (NAT) and respiratory secretions (RS) were collected from 70 patients with histologically confirmed primary lung cancer. DNA was extracted and analysed by nested-PCR targeting the mtLSU rRNA and CYB loci, followed by genotyping. Results Pneumocystis jirovecii was detected in fourteen samples derived from 8/70 individuals (11.4%): two NPL, six NAT and six RS. In two patients, Pneumocystis was detected in all three specimen types; both were diagnosed with the same histological malignancy grade (G3, P =0.036). The genotype distribution varied across sample types in most cases. Conclusions The ability of Pneumocystis to colonize NPL may be linked to the stage of tumour advancement, suggesting that local tumour-related factors could influence its colonization. These findings support further investigation of the lung microbiome in the context of tumour-associated microenvironments and their potential utility as complementary biomarkers in lung cancer.
Szydłowicz et al. (Wed,) studied this question.