The Challenge of Bacterial Infections During Intensive Care Unit Stay After Heart Transplantation.

Background: Infections occurring in the early post-heart transplant (HT) period heavily contribute to morbidity and mortality. Our goal is to evaluate the incidence of hospital-acquired pneumonia/ventilator-associated pneumonia (HAP/VAPs) and/or bloodstream infections (BSIs) after HT during the intensive care unit (ICU) stay and identify their associated risk factors in our tertiary hospital.

Methods: Observational prospective study including all adult patients who consecutively underwent HT from January 1, 2015 to August 31, 2023 at Fondazione IRCCS Policlinico San Matteo, Pavia, Italy. HAP/VAPs and BSIs diagnosed during ICU were included in the analysis.

Results: A total of 106 patients were included, 38 of whom had at least one infectious episode (35.8%), for a total of 57 independent episodes and their incidence was 2.2 per 100 days (95% CI 1.7-2.8). Length of ICU stay was 8 days (IQR: 6-11) for patients without infectious events and 27 days (IQR 14-52) for those with infectious events (p < 0.001). Gram-negative bacteria were associated with 62.8% of BSIs (mainly Enterobacterales) and with 77.9% of HAP/VAP, in this setting Pseudomonas aeruginosa accounted for 17.6% of infections while Klebsiella spp. accounted for 22.1% of infections. Colonization with resistant bacteria (HR 2.21, 95% CI 1.12-4.35) was associated with increased risk of infections while perioperative antimicrobial prophylaxis (PAP) covering Gram-negative bacteria at transplant (HR 0.45, 95% CI 0.23-0.90, p = 0.023) was a protective factor.

Conclusion: This study shows that Gram-negative infections represent the major challenge for HT patients during ICU stay and shows some evidence in support of the PAP covering Gram-negative infections at transplant.