Dismal prognosis of Pneumocystis jirovecii pneumonia in patients with multiple myeloma.

Patients with multiple myeloma (MM) are at high risk for infections, including opportunistic infections such as Pneumocystis jirovecii pneumonia (PJP). We conducted a retrospective analysis of patients with MM developing PJP over a 6-year period between January 2016 and December 2021 at the University Hospital of Würzburg by screening cases of microbiologically documented PJP. A total of 201 positive results for P. jirovecii in respiratory specimens were retrospectively retrieved through our microbiology database. Of these cases, 13 patients with MM fulfilled the definition of probable PJP according to EORTC fungal disease definitions. We observed two peaks in PJP incidence, one after stem cell transplantation during first-line treatment (n = 5) and the other in heavily pretreated patients with six or more prior lines of therapy (n = 6). There was high morbidity with nine (69%) patients admitted to the ICU, seven of whom (78%) required mechanical ventilation, and high mortality (62%, n = 8). Notably, only two of the 13 patients (15%) had received PJP prophylaxis. The main reason for discontinuation of prophylaxis with trimethoprim-sulfamethoxazole was grade IV neutropenia. The observed morbidity and mortality of PJP in MM patients are significant and even higher than reported for patients with other hematologic malignancies. According to most current guidelines, the use of prophylaxis would have been clearly recommended in no more than three (23%) of the 13 patients. This illustrates the need to critically reconsider the indications for PJP prophylaxis, which remain incompletely defined.