Pneumocystis jirovecii Pneumonia: Epidemiology, Clinical Manifestation and Diagnosis

Abstract

The purpose of this study is to provide an understanding of the increased range of patient cohorts at risk of Pneumocystis jirovecii pneumonia (PCP) and describe typical clinical presentations together with advances in diagnostic assays and strategies. The range of immuno-compromised patients at risk of PCP continues to expand. Apart from human immunodeficiency virus (HIV)-positive patients, those with solid tumours or suffering from haematological malignancy, solid organ transplant recipients or with autoimmune and inflammatory conditions receiving immuno-modulating therapies and patients diagnosed with primary immune deficiencies are all at increased risk of PCP. The clinical presentation of respiratory distress may be mild/moderate in the HIV-positive patient, but fulminant in HIV-negative. While typical clinical signs of PCP, along with underlying risk factors and the absence of alternative diagnoses, may be sufficient to commence therapy, every effort should be made to achieve a mycological diagnosis. With the advent of modern diagnostics techniques (real-time polymerase chain reaction (PCR) and (1-3)-β-D-Glucan), a laboratory-based diagnosis should always be attempted, although microscopic identification of Pneumocystis within respiratory samples remains the reference method. By combining different assays, it may be possible to both exclude and confirm PCP, without the need for invasive samples. This review will summarize the epidemiology, clinical manifestations and diagnostic options for PCP, and also briefly cover therapeutic management, the emerging issue of resistance and PCP in paediatric age group.