Epidemiology and risk factors associated with Pneumocystis jirovecii pneumonia in kidney transplant recipients after 6-month trimethoprim-sulfamethoxazole prophylaxis: A case-control study

Background Pneumocystis jirovecii pneumonia (PCP) is an important cause of morbidity and mortality in kidney transplant recipients (KTRs), and prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX) is recommended. The aim of this study was to investigate incidence and risk factors for PCP in KTRs after 6-month TMP-SMX prophylaxis. Methods We conducted a case-control study of patients with PCP who received 6-month PCP prophylaxis with TMP-SMX after kidney transplantation (KT). In cases of rejection, PCP prophylaxis was provided for six additional months after anti-rejection therapy. Cytomegalovirus (CMV) infection was not considered an indication for PCP prophylaxis due to concerns of nephrotoxicity associated with TMP-SMX. Results Among 3941 kidney or pancreas-kidney transplant recipients, 67 (1.7%) developed PCP after discontinuing TMP-SMX. A total of 47 patients with KT PCP and 94 controls were included. Duration of PCP prophylaxis was similar between cases and controls (median 6 months, P = .53). In multivariate analysis, rejection (OR 3.9; 95% CI 1.4-11.1) and CMV infection (OR 2.4; 95% CI 1.0-5.8) were independently associated with PCP development after TMP-SMX. Rejection or CMV infection was observed in 70% of patients with PCP. Time to PCP development after rejection (median [IQR] 6 [5-19] months) was slightly shorter than after CMV infection (median [IQR] 9 [5-12] months; P = .18). Conclusion Post-prophylaxis PCP occurred in <2% of KTRs, and about two-thirds of these experienced rejection or CMV infection. These data suggest that at least 6 to 9-month additional chemoprophylaxis may be needed to prevent PCP in KTRs with transplant rejection or CMV infection.