Lymphopenia is associated with late onset Pneumocystis jirovecii pneumonia in solid organ transplantation

BackgroundPneumocystis jirovecii pneumonia (PJP) affected 5%-15% of solid organ transplant (SOT) recipients prior to universal prophylaxis, classically with trimethoprim-sulfamethoxazole (TMP-SMX). Guidelines generally recommend 6-12months of prophylaxis post-SOT, yet optimal duration and robust PJP risk stratification have not been established. MethodsA retrospective, single-center, case-control study of PJP among SOT recipients from January 1998 to December 2013 was conducted. Cases had positive PJ direct fluorescent antibody assay of respiratory specimens. Controls were matched 4:1 by nearest date of SOT. Univariate testing and multivariate logistic regressions were performed. ResultsFifteen cases were identified among 5505 SOT recipients (0.27% rate) and analyzed vs 60 controls. PJP occurred on average 6.1years (range 0.9-13.8) post-SOT; no case was receiving PJP prophylaxis at diagnosis. Most were treated with reduced immunosuppression and TMP-SMX plus steroids (80%). Six patients (40%) required critical care; 3 (20%) died. There were no significant demographic differences, though cases tended to be older at SOT (54 vs 48years, P=.1). In univariate analysis, prior viral infection was more common among cases (67% vs 37%, P=.08). Lower absolute lymphocyte count (ALC) at diagnosis date was strongly associated with PJP (400 vs 1230x10(6)cells/L, P<.001); odds of infection were high with ALC 500x10(6) cells (OR 18.7, P<.01). ConclusionPneumocystis jirovecii pneumonia is a rare, late complication of SOT with significant morbidity and mortality. Severe lymphopenia may be useful in identifying SOT recipients who warrant continued or reinstated PJP prophylaxis.