<i>Pneumocystis jirovecii</i> pneumonia in non-human immunodeficiency virus patients

Kim, Jinnam; Yoon, Choseok; Kim, Bongyoung; Park, Se Yoon

doi:2026.41.6.1020

Korean J Intern Med > Volume 41(6); 2026 > Article

REVIEW

Infectious diseases

Korean J Intern Med. 2026;41(6):1020-1039. doi: https://doi.org/10.3904/kjim.2026.210

Pneumocystis jirovecii pneumonia in non-human immunodeficiency virus patients

Jinnam Kim^1,2, Choseok Yoon², Bongyoung Kim^1,2, and Se Yoon Park^1,2

¹Department of Internal Medicine, Hanyang University College of Medicine, Seoul, Korea
²Division of Infectious Diseases, Department of Internal Medicine, Hanyang University Seoul Hospital, Seoul, Korea

Corresponding Author: Se Yoon Park , Tel: +82-2-2290-8567, Email: livinwill2@gmail.com

Received: April 15, 2026; Revised: July 28, 2026; Accepted: September 19, 2026.

Abstract

Pneumocystis jirovecii pneumonia (PJP) is an important opportunistic fungal infection in immunocompromised hosts. Although its incidence has declined markedly in people with human immunodeficiency virus (HIV) following the widespread use of antiretroviral therapy and prophylaxis, PJP is increasingly encountered in HIV-negative patients receiving immunosuppressive or targeted immunomodulatory therapies. In this population, PJP often follows a more fulminant course, with rapid progression to severe hypoxemia and acute respiratory failure. Diagnosis remains challenging because clinical manifestations are nonspecific and pulmonary organism burden is often lower than in HIV-associated disease. Accordingly, diagnosis requires integration of host risk factors, radiologic findings, microbiologic testing, and adjunctive biomarkers. Chest computed tomography commonly shows bilateral ground-glass opacities, while bronchoalveolar lavage with microscopy and, increasingly, quantitative PCR remains central to microbiologic confirmation. Serum β-D-glucan may provide useful supportive information but should be interpreted as an adjunct rather than a stand-alone test. Trimethoprim-sulfamethoxazole (TMP-SMX) remains the first-line treatment for PJP, but the optimal dose in HIV-negative patients remains uncertain. Emerging evidence suggests that reduced-dose TMP-SMX may preserve efficacy while improving tolerability in selected patients, whereas standard-dose therapy remains the reference regimen in severe disease. The role of adjunctive corticosteroids in HIV-negative PJP also remains unsettled, supporting a selective rather than routine approach. Prevention remains essential, and current evidence supports risk-adapted primary prophylaxis and individualized secondary prophylaxis for as long as clinically meaningful immunosuppression persists, complemented by infection-control measures in units caring for highly immunocompromised patients.

Keywords: Pneumonia, pneumocystis ; Immunocompromised host ; Antibiotic prophylaxis ; Trimethoprim, sulfamethoxazole drug combination