A review of critical periods for opportunistic infection in the new transplantation era

Background. The risk of opportunistic infection (OI) is considered to be maximum during the first six months after solid organ transplantation. The aim of this study was to know the incidence and risk factors for OI in the late period (> 6 months) compared with the early period (< 6 months) after solid organ transplantation. Methods. We used the online database of the Spanish Network of Infection in Transplantation (RESITRA), which prospectively analyzed 2,702 solid organ transplantation recipients from August 2003 to February 2005. Univariate and multivariate analyses were performed to calculate the risk factors associated with the development of late OI. Results. A total of 131 patients (6%) developed 176 infectious episodes in the late period. Although the incidence of infection and cytomegalovirus disease (0.4 per 1000 transplant days and 0.05 per 1000 transplant days, respectively) was lower than in the early period (3.5 per 1000 transplant days and 0.8 per 1000 transplant days; P < 0.0001), the incidence of other OIs was similar in both periods (0.05 per 1000 transplant days versus 0.03 per 1000 transplant-days, P=0.5). Patients with the higher risk for developing late OI were those receiving early cytomegalovirus prophylaxis, patients who developed two or more episodes of acute rejection during the early period, patients with recurrent bacterial infection during the early period, patients with renal failure requiring dialysis, and patients with chronic graft malfunction. Conclusions. Our data suggest that in some high-risk patients, the critical period of risk for OI must be expanded beyond the first six months after transplant.