As part of a long-term project, we have set out to assess outcomes of targeted diarrheal pathogens among our high-risk transplant population. Our team has clarified rates of bacterial foodborne bacterial infections, C difficile and assessed bloodstream infections from bacteria commonly found in over the counter probiotics. These data indicate high rates of diarrhea among transplant recipients, but also the low incidence of non-C diff bacterial GI infections. Our ongoing studies assessing viral gastrointestinal pathogens, e.g. norovirus, will help to define the epidemiology, treatment, and prevention approaches for these pathogens in high-risk immunocompromised hosts.
Cytomegalovirus remains the most common transplant-associated viral infection for allogeneic transplant populations. As prevention options have increased, there has been a need to identify populations at highest risk for complications, and to address those with unique risks. We have identified that cord blood transplant recipients were at a high risk for CMV related reactivation and disease and developed a prevention strategy that led to significant improvements in associated risk, using a combination of high-dose valacyclovir, enhanced screening, and early interventions. Additionally, we were able to address for the first time, the low risk associated with primary CMV transmission to seronegative recipients from seropositive donors, and demonstrate that the viral genomic content of the donor graft determines transmission efficiency in D+/R- HCT recipients.
We were able to demonstrate that even with significant pressure from standard fluoroquinolone prophylaxis, rates of resistance to these important antibiotics for neutropenia did not increase in HCT recipients. However, the increased rates of death in patients with FQ-resistant GNRs is of major concern, and suggests new options for prophylaxis need to be developed in the coming years. Additionally, we were the first group to show that pre-transplant screening for methicillin-resistant Staphylococcus aureus (MRSA) was of little value in HCT recipients. These data are important as costs for transplant continue to increase, risk of MRSA is shifting in the community, and rates of isolation in high risk patients have become an increasing burden. These data led to a substantial review of isolation policies and procedures, served as a quality review of screening practices in our transplant center, and demonstrated the importance of future studies in patient quality and safety in this high-risk population.
We have developed and fine-tuned an aggressive program of prevention at our center, which helped to stop a large respiratory syncytial virus outbreak in 2007, and was critical to preventing a large outbreak in 2012. We were able to demonstrate that these outbreaks can be limited by aggressive isolation, screening, and front-line prevention. We have also developed, implemented and standardized an influenza vaccine program that has increased vaccination rates using methods which enhance active declination. These efforts have demonstrated to be effective in assuring high-level vaccination, and have provided an alternative to mandatory policies but with an equal rate of success. Finally, we have been able to utilize these prevention strategies to identify and characterize outcomes in emerging respiratory viral pathogens.