Pneumocystis pneumonia in the twenty-first century: HIV-infected versus HIV-uninfected patients

ABSTRACT

Introduction: Pneumocystis pneumonia (PcP) has classically been described as a serious complication in patients infected with the human immunodeficiency virus (HIV). However, the emerging number of conditions associated with immunosuppression has led to its appearance in other patient populations.

Areas covered: This article reviews the most recent publications on PcP in the HIV-infected and HIV-uninfected population, focusing on epidemiology, diagnostic, therapy and prevention. The data discussed here were mainly obtained from a non-systematic review using Medline and references from relevant articles including randomized clinical trials, meta-analyses, observational studies and clinical reviews.

Expert opinion: The growing incidence of Pneumocystis infection in the HIV-uninfected population suggests the need for new global epidemiological studies in order to identify the true scale of the disease in this population. These data would allow us to improve diagnosis, therapeutic strategies, and clinical management. It is very important that both patients and physicians realize that HIV-uninfected patients are at risk of PcP and that rapid diagnosis and early initiation of treatment are associated with better prognosis. Currently, in-hospital mortality rates are very high: 15% for HIV-infected patients and 50% in some HIV-uninfected patients. Therefore, adequate preventive measures should be implemented to avoid the high mortality rates seen in recent decades.

KEYWORDS:

• Pneumonia
• pneumocystis
• HIV
• non-HIV
• community-acquired pneumonia

Article highlights

• Pneumocystis is prevalent in the lungs of immunocompetent individuals, suggesting that asymptomatic healthy adult carriers provide a reservoir for Pneumocystis infection.

• In HIV-infected patients the risk for PcP increases exponentially when the CD4+ cell count is below 200 cells/µl. Patients on ART who develop PcP typically have low CD4+ cell levels due to poor adherence to ART or possible resistance to ART.

• There is a growing incidence of Pneumocystis infection in the HIV-uninfected population due to the emerging number of conditions associated with immunosuppression. These include hematological malignances, solid tumors, solid-organ transplantation, autoimmune diseases, steroids therapy, immunosuppressive or biological therapy.

• There is strong evidence of the presence of Pneumocystis in the air of areas where infected patients reside and of a transmission through interpersonal contacts. It is reasonable to isolate infected patients until respiratory symptoms resolution or discharge from hospital; when patients need to be moved a mask should be worn.

Acknowledgments

C Cillóniz is a recipient of an ERS Short Term Fellowship and Postdoctoral Grant “Strategic plan for research and innovation in health-PERIS 2016–2020”. J M Miro received a personal 80:20 research grant from the Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain, during 2017–19.

Author contributions

All authors were involved in the content development of the manuscript, reviewed all drafts and approved the final version. The authors take full responsibility for the content of this article.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Declaration of interest

J M Miro has received consulting honoraria and/or research grants from AbbVie, Bristol-Myers Squibb, Cubist, Novartis, Gilead Sciences, and ViiV outside the submitted work. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Additional information

Funding

The study was funded by Ciber de Enfermedades Respiratorias (Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES) CB06/06/0028), 2009 Support to Research Groups of Catalonia 911, IDIBAPS.