Background: We observed an outbreak of severe opportunistic infections (OIs) among heart transplant patients coincident with a change from muromonab-CD3 (OKT3) to rabbit anti-thymocyte globulin (Thymoglobulin) for induction immunosuppression. The purpose of this study was to describe the outbreak and, because Thymoglobulin use alone would not be expected to result in such a high rate of OIs, to assess for other risk factors.
Methods: Based on the clustering of cases, the outbreak period was defined as May 2005 to December 2006. The preoutbreak period was defined as January 2003 to April 2005. Clinical and demographic data were collected on all patients who received a transplant during this period, and occurrence of OI was tracked on 14 consecutive patients who received a transplant after resolution of the outbreak.
Results: One hundred two patients underwent heart transplantation during the period studied. Thirteen patients developed severe OIs: 10 during the outbreak period (rate, 10/48 [21%]), 2 before the outbreak (2/50 [4%]), and 1 (1/14 [7%]) in limited follow-up after the outbreak. Opportunistic infections included aspergillosis, nocardiosis, disseminated histoplasmosis, cryptococcal meningitis, mucormycosis, and cytomegalovirus syndrome. In multivariate analysis, patients who received a transplant during the outbreak had a higher risk of OI and were more likely to receive Thymoglobulin than patients who received a transplant before the outbreak. Maintenance prednisone dosing in our patients was higher than in other published series of solid organ transplant recipients treated with Thymoglobulin.
Conclusions: Thymoglobulin induction combined with higher maintenance dosing of prednisone may result in a high rate of serious OIs in heart transplant recipients.