Investigation of Pneumocystis jirovecii in patients diagnosed with lung disease

Colonization with Pneumocystis jirovecii (P. jirovecii), which is in the group of opportunistic fungi, in patients with lung diseases has become a popular topic in current research. In this study, it was aimed to investigate the presence of P. jirovecii with conventional and molecular methods and to perform Dihydropteroate synthase (DHPS) mutation analysis. Bronchoalveolar lavage (BAL) samples taken from a total of 94 patients (38.4% female; 61.7% male) between the ages of 20-85 (53.22±16.47) who were followed-up for lung diseases between September 2018 and 2020 were included in this study. The presence of P. jirovecii in BAL samples was conventionally determined by Indirect Fluorescent Antibody Test (IFA) and by quantitative Polymerase Chain Reaction (qPCR) with targeted mtLSU gene region, and the possible drug resistance status was investigated by qPCR with DHPS primers. P. jirovecii was detected in 22 (23.4%) of 94 BAL samples by PCR and in 20 (21.3%) by IFA, and the methods were found to be moderately compatible (κ=0.387; p <0.001). It was determined that P. jirovecii PCR positive patients have diagnosed with lung cancer in 12 (%54.5), COPD in 8 (%36.4), interstitial lung disease in 1 (%4.5) and pneumonia in 1 (%4.5) (p <0.001), and only wild type P. jirovecii was detected in 12 of these 22 patients (54.5%) with the DHPS amplification profile. Although the P. jirovecii positivity of 23.4% found in people with chronic lung disease was predominantly evaluated in favor of colonization, it was thought that these patients might be at risk for the development of PCP with suppression of the immune system. Moreover, despite the fact that only wild type P. jirovecii was detected in this study is a promising finding for our country, it is clear that further studies are needed to evaluate both the presence of P. jirovecii and drug resistance status.