2026 Eastern States Conference

Title: Characterization of Pneumocystis jirovecci Pneumonia (PJP) prophylaxis strategies and breakthrough PJP during pediatric Hematopoietic Stem Cell Transplantation (HSCT)
Authors: Corinne Berkery, PharmD; Mikayla Mariano, PharmD; Jennifer Szwak, PharmD, BCPS, DPLA, FCCP; Blair Nuoffer, PharmD, BCPPS; Jessica White, PharmD, BCPPS; Amanda Memken, PharmD, BCPPS; Cambree Fillis, PharmD, BCOP
Learning Objective: Describe strategies for PJP prophylaxis in HSCT recipients
Background/Objective: This study aimed to evaluate current PJP prophylaxis strategies at Johns Hopkins Children’s Center (JHCC) and Johns Hopkins All Children's Hospital (JHACH) by describing the use, efficacy, and safety of PJP prophylaxis strategies pre- and post-HSCT.
Methods: This was a single center, multisite, retrospective, observational, cohort study including patients under 25 years of age who underwent allogeneic HSCT and received PJP prophylaxis at JHCC and JHACH between 01/01/2021 and 10/31/2025. Patients were excluded if they underwent autologous transplant or had incomplete medical records precluding outcome assessment. Baseline characteristics were collected including age, sex, indication for transplant, conditioning intensity, donor type, graft source, and graft-versus-host-disease prophylaxis strategy post-transplant. Outcome data were collected from day -10 through day +180. Descriptive statistics were used to summarize data. Time to engraftment between sulfamethoxazole-trimethoprim (TMP-SMX) and pentamidine was compared with a Mann-Whitney U test using STATA.
Results: Of 305 transplants reviewed, 160 were included. Prior to HSCT, 87 (54%) received TMP-SMX prophylaxis and 73 (46%) received pentamidine (intravenous or inhaled). Pentamidine was the predominant prophylactic agent utilized post-HSCT, with 145 (90%) of transplants initially receiving pentamidine and 7 (4%) TMP-SMX. Most transplants (70%) changed agents during the post-HSCT period. One patient (0.6%) had a proven PJP infection on day +17 post-HSCT. There was no difference in median time to platelet engraftment with pre-HSCT pentamidine compared to TMP-SMX (28 vs. 29 days, p=0.59). The median time to neutrophil engraftment was shorter for patients receiving pre-HSCT pentamidine compared to TMP-SMX (16 vs. 17 days, p=0.04).
Conclusions: A low incidence of breakthrough PJP (<1%) was observed among patients receiving PJP prophylaxis. The variability in strategies across sites within a single health system highlighted an opportunity to standardize pre- and post-HSCT PJP prophylaxis practices.
Self-Assessment Question: If a patient has severe thrombocytopenia post-HSCT, which agent would most likely be used for PJP prophylaxis?
a. TMP-SMX
b. Pentamidine
c. Dapsone
d. Atovaquone