Nocardia Infections

Nocardial infections have been rare after allogeneic hematopoietic stem
cell transplantation (HSCT). We report 10 recent cases of late-onset
nocardiosis (median time of onset of 508 days after transplantation)
primarily in patients on high doses of corticosteroids for
graft-versus-host disease. All 10 patients had pulmonary infection caused
by Nocardia species susceptible to trimethoprim-sulfamethoxazole
(TMP-SMX). At time of diagnosis 8 of 10 patients were not receiving
TMP-SMX for prophylaxis of Pneumocystis jiroveci pneumonia (PJP; 7 on
atovaquone, 1 on i.v. pentamidine). After the initiation of atovaquone
prophylaxis for PJP in place of TMP-SMX for many UCLA allogeneic HSCT
patients in 2012, 9 cases of nocardiosis occurred in 411 patients (2.2%)
over the next 6 years (2012 to 2017) compared with only 1 case in 575
patients (0.17%) during the previous 12 years (2000 to 2011). Although
there were no deaths directly related to nocardial infection treated
primarily with TMP-SMX, overall mortality in this group of patients was
40%. Based on this experience, the use of atovaquone for PJP prophylaxis
in place of TMP-SMX may be associated with an increased risk for
previously rare nocardial infections after allogeneic HSCT.