Allogeneic donor transplant have to carefully watch out for infections following transplant. A lung condition called bronchiolitis obliterans syndrome (BOS) can complicate allo transplant so an antibiotic called azithromycin was tested to counter this type of infection. Researchers recently found, however, that more patient deaths occurred on azithromycin than without. In a study called Azithromycin Increases Mortality After Hematopoietic Stem Cell Transplantation , 480 blood cancer allo transplant patients patients received either 2 years of azithromycin ((250 mg three times weekly) or placebo.

The study was stopped after 13 months when it was determined that the risk for hematologic malignancy relapse was increased with azithromycin versus placebo (33.5% vs. 22.3%; hazard ratio, 1.7; P=0.002).

Azithromycin recipients also had reduced airflow decline–free survival (the primary outcome; 32.8% vs. 41.3%; P=0.03), more cases of BOS (6% vs. 3%), and reduced 2-year survival (56.6% vs. 70.1%; P=0.02). Discontinuation rates were similarly high (>50%) in both treatment groups.

If you are an allo transplant patient, ask your doctor which antibiotics will be most protective and safe for your recovery.