Pneumocystis Pneumonia

Abstract

In Brief Major controversies persist regarding the diagnosis and management of Pneumocystis pneumonia (PCP). Of considerable significance is the fact that much of the available evidence relates to human immunodeficiency virus (HIV)–infected subjects and may not be applicable to other immunocompromised groups. Induced sputum (IS) remains an important diagnostic test with a high specificity and good patient acceptability. Immunofluorescence improves the sensitivity of IS when compared with standard cytochemical staining. Nucleic acid amplification techniques may also increase sensitivity, although they remain predominantly a research tool. Bronchoscopy with bronchoalveolar lavage (BAL) is the optimum diagnostic test, with bilobar washing including an upper lobe reaching sensitivities of 95%. BAL, rather than IS, should be performed as the initial diagnostic investigation in non–HIV-infected subjects where the Pneumocystis pathogen load is low. Transbronchial biopsy is no more sensitive than bilobar lavage and is associated with considerable morbidity. Nonbronchoscopic lavage is an underused diagnostic resource offering a cheap alternative to fiberoptic bronchoscopy. Early diagnostic evaluation with BAL rather than empirical treatment is encouraged since the chance of detecting Pneumocystis after several days of anti-Pneumocystis treatment is reduced. In addition, multiple respiratory pathogens are common in patients with low CD4 counts. This strategy of early BAL is particularly important in non–HIV-infected immunocompromised patients where there is greater uncertainty regarding the clinical diagnosis of PCP. Pneumocystis pneumonia remains a serious infection in both human immunodeficiency virus (HIV)–infected and noninfected immunocompromised populations. This review explores controversies in both the diagnosis and management of Pneumocystis pneumonia (PCP); notably the advantages and disadvantages of induced sputum and bronchoalveolar lavage for diagnosis, the optimum methods for identifying Pneumocystis in specimens, and the timing of the introduction of highly active antiretroviral therapy following HIV-PCP coinfection.