Nipping Post-transplant Infections in the Blood

Solid organ transplantation (SOT) saves the lives of those with organ failure. In the U.S. alone, nearly 40,000 organ transplants are performed each year. However, with a life-saving organ transplant comes an increased risk of post-transplant complications, including blood stream infections (BSI). BSIs occur in up to 30% of patients after liver transplantation, and infections increase mortality in this population. Although all SOT patients have an increased risk of BSI, operative and anatomical factors such as level of immunosuppression, direct intestinal disruption, and likelihood of post-operative critical illness can increase risk for some organ transplants more than others. For example, liver transplant includes a higher risk of BSI with enterococci because of biliary and intestinal involvement. Conversely, kidney transplant recipients are at higher risk of BSI due to urinary tract pathogens such as Escherichia coli and Klebsiella spp.

Blood cultures from a total of 2,293 transplant patients were drawn for clinical care in the first year post-SOT and assessed for infection, with pathogen identification and antimicrobial susceptibility performed by the microbiology laboratory. Their results indicated that 8.5% of the cohort developed at least one BSI in the year following the transplant, with the highest risk in multi-organ transplant recipients, followed by liver, heart and kidney. There were 313 BSI episodes identified, 10 of which included two organisms, yielding 323 unique isolates. They also found that 29.1% of patients with BSI experienced multiple BSI episodes. Again, this was found to be most common in multi-organ and liver recipients. The most prevalent organisms isolated in the study were Klebsiella spp. (Enterobacterales) followed by E. coli, Enterococcus faecium, P. aeruginosa and S. aureus. Out of the 323 isolates, 45.5% were MDROs—a striking proportion—with liver transplant recipients harboring the most, followed by multi-organ transplant recipients. When they analyzed outcomes at 90 days after BSI onset, they found 9.7% mortality, though no specific patient characteristic (age, race, gender, transplant type, ICU admission at time of transplant, or Charlson comorbidity index) was associated with increased mortality after BSI. The only patient or organism characteristic independently associated with 90-day mortality after BSI was vancomycin-resistant Enterococcus, which was significantly associated with mortality in both univariable and multi-variable models.

While this study is limited to a single center and did not include data on confounding factors, it does provide important insights into prevalence of BSI in SOT recipients. Their finding that multi-organ transplant recipients have a significant BSI burden has not previously been shown and warrants further study. As does their data on high MDRO burden among SOT patients in a high-volume transplant center.