STUDY OF THE DISTRIBUTION OF PNEUMOCYSTOSIS IN BULGARIA BETWEEN SEPTEMBER 2017 AND APRIL 2019 BY USING REAL- TIME PCR

Pneumocystis jirovecii is an opportunistic organism that inhabits predominantly the human pulmonary alveoli. The fully sequenced genome of P. jirovecii was first reported in 2012. According to some authors, P. jirovecii is an obligate pathogen because genes encoding virulence factors and most enzymes for amino acid biosynthesis were not found in the genome. This suggests that the microorganism normally colonises the human lungs but causes disease only in immunocompromised persons. Pneumocystis pneumonia (PCP) is one of the most common opportunistic infections in patients developing acquired immune deficiency syndrome (AIDS). The use of conventional microscopic methods in diagnosis is associated with considerable limitations. Therefore, detection of Pneumocystis DNA in clinical samples by PCR techniques leads to significant advances in the diagnosis of PCP. The aim of this study is to determine the importance of PCR-based methods in the diagnosis of human pneumocystosis and to evaluate their diagnostic value in comparison with conventional microscopy methods. For a period of 20 months in the National Reference Laboratory “Diagnosis of Parasitic Diseases” at the National Centre of Infectious and Parasitic Diseases 33 patients were tested by real-time PCR and 11 of them were found positive for the presence of P. jirovecii DNA. Eight of the patients (72.7%) were HIV-infected. Although limited in extent, this is the first real-time PCR study on the distribution of human pneumocystosis in Bulgaria. Our data shows that PCR techniques have higher sensitivity and specificity than microscopic methods and provide new opportunities for the diagnosis of Pneumocystis pneumonia.