Examine current real-world utilization of mcfDNA using a multi-center retrospective registry. To achieve this aim, we will utilize a multi-center REDCap database to examine and summarize patient demographics and types of transplants where mcfDNA was used. We will classify cases based on common syndromes/indications for which mcfDNA is sent, timing of the test, and clinically relevant microbiologic yield of mcfDNA results.

Identify clinical predictors where mcfDNA outperforms CMT. We will analyze specific clinical syndromes where mcfDNA has higher yield compared to CMT including pneumonia, visceral abscesses, CNS infections, etc. We will also
identify specific pathogens that are more likely to be detected by mcfDNA earlier in the clinical course such as bartonella, syphilis, parasitic infections, and other atypical bacteria, mycobacteria, and fungi.

Analyze clinical impact of mcfDNA to assess whether the use of the test had a positive vs. negative vs. neutral impact on patient care using pre-specified definitions. Additionally, we will perform clinical adjudication of positive and
negative mcfDNA cases using standardized criteria and analyze effect of timing of test ordering on clinical impact.