Prophylaxis of pneumocystis jirovecii

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Pneumocystis jirovecii is a unicellular yeast-like fungus, which is capable of causing pneumonia in humans, though it is usually only a problem in patients with some degree of immunocompromise, such as those receiving chemotherapy or with HIV/AIDS. The pneumonia caused by Pneumocystis jirovecii is commonly abbreviated to PCP, based on alternative nomenclature for Pneumocystis jirovecii, Pneumocystis carinii (Gigliotti, 2005), hence Pneumocystis carinii pneumonia.

The medication of choice for preventing or treating PCP is the combination antibiotic co-trimoxazole. Co-trimoxazole is a combination antibiotic consisting of a mixture in the ratio 1:5 of trimethoprim and sulfamethoxazole (Electronic Medicines Compendium (eMC), 2018a).

For children, a suggested dose of co-trimoxazole for prophylaxis is 450 mg/m² twice daily for three days of the week (Joint Formularies Committee, 2019).

In contrast to the prophylactic dose, the treatment dose is 120 mg/kg/day in 2-4 divided doses (Joint Formularies Committee, 2019).