OBJECTIVES: To report on the temporal relationship between administration of trimethoprim/sulfamethoxazole to medically immunosuppressed HIV-negative renal patients with Pneumocystis jirovecii pneumonia (PCP) and the development of an acute psychosis. METHODS: We investigated a retrospective case series of renal transplant and immunosuppressed patients with PCP within an ongoing outbreak in the northwest of England since 2009. Four patients with PCP developed psychosis following treatment with trimethoprim/sulfamethoxazole. RESULTS: Four of twenty patients developed acute psychoses following administration of trimethoprim/sulfamethoxazole, including one accidental re-challenge. Symptoms resolved within 24 h of changing the therapy. The striking temporal relationship between the initiation and discontinuation of the drug and the behavioural changes suggests a causal relationship. CONCLUSIONS: With increasing solid organ transplantation and the use of immunosuppressants, vigilance regarding trimethoprim/sulfamethoxazole dose modification is required and the routine use of therapeutic drug monitoring should be considered.
OBJECTIVES: To report on the temporal relationship between administration of trimethoprim/sulfamethoxazole to medically immunosuppressed HIV-negative renal patients with Pneumocystis jirovecii pneumonia (PCP) and the development of an acute psychosis. METHODS: We investigated a retrospective case series of renal transplant and immunosuppressed patients with PCP within an ongoing outbreak in the northwest of England since 2009. Four patients with PCP developed psychosis following treatment with trimethoprim/sulfamethoxazole. RESULTS: Four of twenty patients developed acute psychoses following administration of trimethoprim/sulfamethoxazole, including one accidental re-challenge. Symptoms resolved within 24 h of changing the therapy. The striking temporal relationship between the initiation and discontinuation of the drug and the behavioural changes suggests a causal relationship. CONCLUSIONS: With increasing solid organ transplantation and the use of immunosuppressants, vigilance regarding trimethoprim/sulfamethoxazole dose modification is required and the routine use of therapeutic drug monitoring should be considered.