High prevalence of Pneumocystis jirovecii colonization among patients with autoimmune inflammatory diseases and corticosteroid therapy.

Background: Patients with autoimmune inflammatory diseases (AID) account for 13-36% of Pneumocystis pneumonia (PCP) cases in human immunodeficiency virus (HIV)-negative patients. Up to 88% of PCP cases in HIV-negative patients are associated with prior steroid treatment. Pulmonary colonization with Pneumocystis in HIV-negative patients is associated with corticosteroid therapy in up to 75% of cases. The aim of this study was to detect the prevalence and risk factors of pulmonary colonization with Pneumocystis jirovecii in patients with AID receiving corticosteroid therapy in comparison with healthy control persons.

Methods: We investigated induced sputa of 102 patients with AID on current corticosteroid treatment and of 117 healthy controls for the presence of P. jirovecii using polymerase chain reaction (PCR).

Results: Twenty-nine patients (28.5%) with AID were colonized with P. jirovecii compared to three healthy controls (2.6%) [p < 0.001, odds ratio (OR) 15.10, 95% confidence interval (CI) 4.43-51.38]. In patients with AID, age over 60 years was significantly associated with colonization (p = 0.015, OR 3.19, 95% CI 1.27-7.94). Multivariate analysis showed age to be independently associated with the colonization of P. jirovecii (95% CI 1.002-1.092). Neither duration nor dose of corticosteroid therapy nor immunosuppressive co-medication had a significant influence on P. jirovecii colonization.

Conclusion: Patients with AID, especially those over 60 years of age, display a high prevalence of colonization with P. jirovecii. Clinicians should be aware of this and ensure that they consider the possibility of PCP when pulmonary symptoms arise in these patients.