Pneumocystis jirovecii: a review with a focus on prevention and treatment

ABSTRACT

Introduction: Pneumocystis jirovecii (PJ) is an opportunistic fungal pathogen that can cause severe pneumonia in immunocompromised hosts. Risk factors for Pneumocystis jirovecii pneumonia (PJP) include HIV, organ transplant, malignancy, certain inflammatory or rheumatologic conditions, and associated therapies and conditions that result in cell-mediated immune deficiency. Clinical signs of PJP are nonspecific and definitive diagnosis requires direct detection of the organism in lower respiratory secretions or tissue. First-line therapy for prophylaxis and treatment remains trimethoprim-sulfamethoxazole (TMP-SMX), though intolerance or allergy, and rarely treatment failure, may necessitate alternate therapeutics, such as dapsone, pentamidine, atovaquone, clindamycin, primaquine and most recently, echinocandins as adjunctive therapy. In people living with HIV (PLWH), adjunctive corticosteroid use in treatment has shown a mortality benefit.

Areas covered: This review article covers the epidemiology, pathophysiology, diagnosis, microbiology, prophylaxis indications, prophylactic therapies, and treatments.

Expert opinion: TMP-SMX has been first-line therapy for treating and preventing pneumocystis for decades. However, its adverse effects are not uncommon, particularly during treatment. Second-line therapies may be better tolerated, but often sacrifice efficacy. Echinocandins show some promise for new combination therapies; however, further studies are needed to define optimal antimicrobial therapy for PJP as well as the role of corticosteroids in those without HIV.

KEYWORDS:

• HIV
• immunosuppression
• Pneumocystis jirovecii
• Pneumocystis jirovecii pneumonia
• prophylaxis

Article highlights

• Pneumocystis jirovecii, though initially mislabelled as a protozoon, is an opportunistic fungal pathogen.

• The significant decrease in incidence of PJP can be attributed to prophylactic treatment for at-risk populations.

• As future immunomodulating therapies are developed, the indications for PJP prophylaxis will expand.

• In PLWH, randomized control trials have found TMP-SMX to have the best efficacy for treatment and prophylaxis.

• There is a need for well controlled PJP studies in non-HIV populations.

• Echinocandins may be able to augment the effectiveness of standard therapy.

This box summarizes key points contained in the article.

Declaration of interest

No potential conflict of interest was reported by the author(s).

Reviewer disclosures

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

Additional information

Funding

This manuscript was not funded.