The impact of cytomegalovirus infection on clinical severity and outcomes in kidney transplant recipients with Pneumocystis jirovecii pneumonia

Cytomegalovirus (CMV) infection is associated with Pneumocystis jirovecii pneumonia (PJP) in kidney transplant recipients (KTRs), but its impact on clinical severity and outcomes in KTRs with PJP is unknown. We reviewed 1994 medical records of KTRs from January 1997 to March 2019. PJP or CMV infection was diagnosed by polymerase chain reaction or culturing using blood or respiratory specimens. We divided patients into PJP and PJP+CMV groups, and evaluated the clinical severity and outcomes. Fifty two patients had PJP (2.6%) in the whole study cohort. Among patients with PJP, 38 (73.1%) had PJP alone and 14 (26.9%) had combined PJP and CMV co-infection. The PJP+CMV group showed worse laboratory findings (serum albumin and C-reactive protein, P = 0.010 for both) and higher requirement of continuous renal replacement therapy than the PJP group (P = 0.050). The pneumonia severity was worse in the PJP+CMV group than in the PJP group (P < 0.05), and CMV infection was a high risk factor of pneumonia severity (odds ratio 16.0; P = 0.002). The graft function was worse in the PJP+CMV group (P < 0.001), and the incidence of graft failure was higher in the PJP+CMV group than in the PJP group (85.7% vs 36.8%; P < 0.001). Mortality was double in the PJP+CMV group than in the PJP group, but not statistically significant (21.4% vs 10.5%; P = 0.370). Our results show that approximately one in four patients with PJP after kidney transplantation develops CMV with increased clinical severity and risk of graft failure. The possibility of increased clinical severity and worse clinical outcomes by CMV co-infection should be considered in KTRs with PJP.