Has the time come for routine trimethoprim-sulfamethoxazole prophylaxis in patients taking biologic therapies?

Patients with inflammatory diseases are treated with a variety of biologic agents. The association between use of biologics and tuberculosis is well known. Additionally, there are numerous case reports of infections in patients receiving biologics with organisms such as Pneumocystis, Listeria, Legionella, and Salmonella. Data from the US Food and Drug Administration Adverse Event Reporting System suggest that infection with these organisms in patients receiving infliximab is at least 5 times as frequent as would be expected if there was no association between use of the drug and the infection. Each of these organisms is typically susceptible to trimethoprim-sulfamethoxazole (TMP-SMZ), and this therefore represents a potentially attractive prophylaxis to prevent these infections in patients receiving biologics. A randomized controlled trial of TMP-SMZ prophylaxis in patients receiving biologics is necessary to prove that its utility outweighs risk, but may be best preceded by a multisite case-control study to determine which patients receiving biologics are at greatest risk.