LAUSR

Abstract Background Trimethoprim/sulfamethoxazole (TMP/SMX) is the agent of choice for Pneumocystis jirovecii Pneumonia (PJP) prophylaxis in renal transplant (RT) recipients. All other prophylactic agents are considered second-line due to efficacy, drug intolerances, cost, administration requirements, and lack of coverage of Toxoplasma. Anecdotally, alternative agents are commonly used at our institution due to clinician hesitancy and perceived risk of adverse drug reactions (ADRs). Our objective was to assess the safety of TMP/SMX prophylaxis in RT recipients. Methods RT recipients transplanted at a tertiary US medical center between May 9, 2015 and November 30, 2017 were retrospectively identified. Patient charts were reviewed for antimicrobial agents used for PJP prophylaxis and ADRs due to TMP/SMX. ADRs were classified using the National Institutes of Health, Division of Microbiology and Infectious Diseases (DMID) criteria and were scored for probability of association with TMP/SMX using the Naranjo ADR probability scale. Results During the study period, 64 of 95 adult RT recipients (67.4%) received TMP/SMX for PJP prophylaxis. Of the patients who received TMP/SMX, 26 (40.6%) had a clinician-documented ADR attributed to TMP/SMX and 24 (37.5%) had the drug discontinued. The most frequent provider-reported ADRs due to TMP/SMX were hyperkalemia (10 patients, 15.6%), neutropenia (nine patients, 14.1%), and elevated liver function tests (LFTs) (three patients, 4.7%). However, when classified using DMID criteria, nine of the 26 ADRs were less severe than Grade 1. Two ADRs were Grade 3 (severe), including 1 case each of neutropenia and elevated LFTs. No ADRs were Grade 4 (life-threatening). All ADRs received a score ≤4 on the Naranjo ADR probability scale, indicating a possible ADR related to TMP/SMX. Often, ADRs did not resolve or other additional medication adjustments were needed following TMP/SMX discontinuation (19 of 26 patients, 73.1%). No cases of PJP occurred. Conclusion TMP/SMX is underutilized in RT recipients at our institution, despite being well-tolerated and efficacious. Clinician hesitancy with TMP/SMX in this population may be unfounded. Internal efforts are underway to increase the use of TMP/SMX in RT recipients. Disclosures All authors: No reported disclosures.