How to diagnose and treat a patient without human immunodeficiency virus infection having Pneumocystis jirovecii pneumonia?

Pneumocystis jirovecii pneumonia (PCP) incidence is increasing in patients without HIV infection. In contrast to PCP in patients infected with HIV, diagnosis is often delayed and illness is associated with increased mortality.To provide a comprehensive review of clinical presentation, risk factors, diagnostic strategies, and treatment options for PCP in patients without HIV infection.Web-based literature review on PCP for trials, meta-analyses, and systematic reviews using PubMed. The restriction to the English language was applied.Common underlying conditions in patients without HIV infection having PCP are haematological malignancies, autoimmune and inflammatory diseases, solid organ or haematopoietic stem cell transplant, and previous corticosteroid exposure. New risk groups include patients receiving monoclonal antibodies and immunomodulating therapies. Patients without HIV infection who have PCP present with rapid onset and progression of pneumonia, increased duration of hospitalization and a significantly higher mortality rate than patients infected with HIV. PCP is diagnosed by a combination of clinical symptoms and radiological as well as mycological features. Results of immunofluorescence microscopy from bronchoalveolar lavage, PCR testing, and computed tomography imaging as well as the evaluation of clinical presentation are required. The established treatment regime consists of trimethoprim and sulfamethoxazole.Although the number of patients with immunosuppression due to causes different from HIV is increasing, a simultaneous rise in PCP incidence is observed. In the group of patients without HIV infection, rapid onset of symptoms, a more complex course, and a high mortality rate are recorded. Therefore, the time to diagnosis must be as short as possible to initiate effective therapy promptly. This review aims to raise awareness of PCP in an increasingly affected at-risk group and provides clinicians with a practical guide for efficient diagnosis and targeted therapy. Furthermore, it intends to display current inadequacies in research on the topic of PCP.