Pneumocystis jiroveci detection using the polymerase chain reaction in patients with sarcoidosis

Two cases of infection due to the atypical fungus Pneumocystis jiroveci in patients with sarcoidosis have been reported until now. This study tested the possibility that prevalence of P jiroviici infection in this patient population may be underestimated because of the use of low sensitivity microscopic techniques. Sixteen archival bronchoalveolar lavage specimens from 16 HIV-negative patients diagnosed with sarcoidosis, and initially tested negative for P. jiroveci using microscopy were retrospectively examined using PCR at the mitochondrial large subunit rRNA. R jiroveci was detected by PCR in four of the 16 patients. As three of these four positive patients were not treated with corticosteroids (CS) at the time of BAL procedure, the role of CS in P. jiroveci occurrence was excluded. The patients were considered to be merely colonized by P. jiroveci since a clinical improvement was observed over a mean period of 16.2 months despite the absence of treatment for the fungus. P. jiroveci was significantly more frequent in patients presenting severe sarcoidosis than in patients with mild sarcoidosis (3/4 vs. 1/12, RR, 9; 95%CI, 1.27-63.89, P = 0.03) suggesting that the fungus may play a role as an aggravating factor of the underlying pulmonary disease. This hypothesis and the frequency of P jiroveci in patients with sarcoidosis justify a further multi-centric case control study to clarify the relationship between the fungus and sarcoidosis.