Reported Beta Lactam and Other Antibiotic Allergies in Solid Organ and Hematopoietic Cell Transplant Recipients

BACKGROUND: Patients with reported beta lactam antibiotic allergies (BLA) are more likely to receive broad-spectrum antibiotics and experience adverse outcomes. Data describing antibiotic allergies among solid organ transplant (SOT) and hematopoietic cell transplant (HCT) recipients are limited. METHODS: We reviewed records of adult SOT or allogeneic HCT recipients from 1/1/2013-12/31/2017 to characterize reported antibiotic allergies at time of transplant. Inpatient antibiotic use was examined for 100 days post-transplant. Incidence rate ratios (IRR) comparing antibiotic use in BLA and non-BLA groups were calculated using multivariable negative binomial models for two metrics: days of therapy (DOT)/1000 inpatient days and percentage of antibiotic exposure days. RESULTS: Among 2153 SOT (65%) and HCT (35%) recipients, 634 (29%) reported any antibiotic allergy and 347 (16%) reported BLA. Inpatient antibiotics were administered to 2020 (94%) patients during the first 100 days post-transplant; average antibiotic exposure was 41% of inpatient days (Interquartile range (IQR) 16.7%, 62.5%). BLA patients had significantly higher DOT for vancomycin (IRR 1.4; 95% confidence interval (CI) [1.2, 1.7]; p<0.001), clindamycin (IRR 7.6; 95% CI [2.2, 32.4]; p=0.001), aztreonam in HCT (IRR 9.7; 95% CI [3.3, 35.0]; p<0.001), and fluoroquinolones in SOT (IRR 2.9; 95% CI [2.1, 4.0]; p<0.001); these findings were consistent when using percentage of antibiotic exposure days. CONCLUSIONS: Transplant recipients are frequently exposed to antibiotics and have a high prevalence of reported antibiotic allergies. Reported BLA was associated with greater use of beta lactam antibiotic alternatives. Pre-transplant antibiotic allergy evaluation may optimize antibiotic use in this population.