Primary prevention

Pneumocystis pneumonia (PCP) can be prevented in patients who are HIV-positive by the implementation of combination antiretroviral therapy (ART), with the goal of restoring and preserving immunological function.[22][32][46]

Specific primary prophylactic treatment is required in all patients who are at high risk of PCP infection.

Adult or adolescent, HIV-positive[32]

  • HIV-positive patients who have no clinical symptoms or signs of PCP require primary chemoprophylaxis in the following circumstances:

    • CD4 cell count <100 cells/microlitre regardless of plasma HIV levels

    • CD4 cell count between 100 and 200 cells/microlitre if plasma HIV RNA levels are above detection limits.

  • Patients who are receiving pyrimethamine/sulfadiazine for treatment or suppression of toxoplasmosis do not require additional prophylaxis for PCP.

Children with or at risk of HIV[22]

  • PCP prophylaxis is recommended for the following groups of children:

    • Age 1 to 12 months who are HIV-positive regardless of CD4 cell count or percentage

    • Age 1 to <6 years who are HIV-positive with a CD4 cell count <500 cells/microlitre or CD4 percentage <15%

    • Age ≥6 to 12 years who are HIV-positive with CD4 cell counts of <200 cells/microlitre or CD4 percentage <15%

    • HIV-indeterminate infants of HIV-positive mothers.

HIV-negative, immunocompromised patients[31][47][48][49]

  • Indications for PCP prophylaxis following assessment of the risk for PCP include patients with:

    • Haematological malignancies

    • Haematopoietic cell transplantation

    • Other malignancies where chemotherapy regimen is associated with >3.5% risk of PCP

    • Solid-organ transplantation

    • Chronic use of corticosteroids with or without other immunosuppressive drugs

    • Certain primary immunodeficiencies (e.g., severe combined immunodeficiency).

Prophylactic agent of choice in children, adolescents, and adults is trimethoprim/sulfamethoxazole (TMP/SMX), in the absence of contraindications.[22][32]​​ Alternatives for adolescents and adults, regardless of Toxoplasma gondii serostatus, include dapsone plus pyrimethamine plus folinic acid; or atovaquone. Alternatives for adolescents and adults who are seronegative for Toxoplasma gondii include: dapsone; aerosolised pentamidine; or intravenous pentamidine.[32] Dapsone, atovaquone, and aerosolised pentamidine are suitable alternatives in children. Intravenous pentamidine may also be considered in children aged >2 years when other options are not available.[22] All patients should be checked for glucose-6-phosphate dehydrogenase (G6PD) deficiency prior to starting dapsone, if possible. For full details of PCP prophylaxis, please see the Management sections.

Although there are data suggesting that person-to-person transmission of the organism occurs, respiratory isolation of patients with PCP is not recommended currently.[32][50][51][52][53]

Vaccines are currently in developmental stages.[54][55][56][57][58][59]

Secondary prevention

Patients who have had PCP infection, who have been treated and are without symptoms, receive secondary prophylaxis, which conforms to the same schedule as primary prophylaxis for each patient group.

Secondary prophylaxis is recommended for HIV-positive patients who have had PCP and should be started after completion of PCP treatment and continued until immune reconstitution occurs with ART.[22][32]

Secondary prophylaxis can be discontinued for most patients using the same criteria as for discontinuing primary prophylaxis. PCP prophylaxis should not be discontinued in HIV-infected infants aged <1 year. Prophylaxis should be continued for life in patients who develop PCP despite CD4 count >200 cells/microlitre.

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