Surgical site infections in liver transplantation in the era of multidrug-resistant bacteria

Background: Surgical site infection (SSI) is the major complication in orthotopic liver transplantation (LT). It is of prime importance to assess the incidence of infections in liver transplants and to analyze the risk factors associated with morbidity and mortality. Methods: Between 2014 and 2019, we performed a retrospective cohort study at the Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy. The liver transplant procedure and its related infections were examined in 4 timepoints, both prior and post-surgery. Multiple random-intercept Poisson regression models with robust variance were fitted to calculate the adjusted risk ratios (RR) and the 95% confidence intervals (CI) according to selected recipient and donor variables. Results: We included in the analysis 249 transplants (in 241 patients). The SSIs (mostly due to S. aureus, E. faecium, and K. pneumoniae) were 7 (2.8%) in the days following LT, increasing to 61 (24.5%) within the first month after LT, and declining to 35 (14.1%) between 31 and 60 days, and to 19 (7.6%) afterwards. The factors associated with increased risk of infection were age (RR=1.17 per 10 years, CI: 0.99-1.38), BMI (RR=1.04 per BMI Unit, CI: 0.99-1.08), donor age (RR=0.88 per 10 years, CI: 0.78-0.98), re-interventions (30 infections, RR=2.02, CI: 1.21-3.38) and the Roux-en-Y approach (25 infections, RR=2.75, CI: 1.47-5.15). Conclusions: The risk of infection occurred mainly in the first two months after LT. Important determinants were age and BMI, donor age, reinterventions, and Roux-en-Y procedure. Our study suggests that these factors should be assessed when performing LT.