Central line-associated bloodstream infections, or CLABSIs, are a major challenge for the health care system, leading to prolonged hospital stays, increased patient mortality, and higher costs.
Staphylococcus epidermidis is the primary cause of these central line-associated infections, which are estimated to cause more than 28,000 deaths per year and cost over $2 billion. A second-year clinical and microbiology fellow in UNMC’s Department of Pathology, Microbiology and Immunology is studying whether whole genome sequencing can be a useful tool to characterize S. epidermidis isolates that are associated with CLABSIs.
“Staphylococcus epidermidis can be a colonizer that lives harmlessly on the skin. It can also be a pathogen causing bloodstream infections through in-dwelling catheters,” said the fellow, Chunyi Zhou, MD, PhD. “This project is trying to use whole-genome sequencing to determine whether it’s more likely that the S. epidermidis isolated from the blood is a real pathogen causing bacteremia or likely acquired from contamination from the blood draw.
“In multiple blood draws from different sites, if the same strain of S. epidermidis is recovered, then we can presume it’s more likely a real S. epidermidis bloodstream infection,” she said. “But if in one draw you recover an isolate of S. epidermidis that is a lot different than the isolate from the blood draw from a different site, it’s more likely that they are contamination.
“We can use whole-genome sequencing to determine how closely related the isolates are from the same patients, based on the threshold we set,” she said. “If there are 50 different base pairs between strains, we call them different strains, which would suggest contamination rather than infection.”
Her study is made possible by the department’s Research Grant Awards, created in 2024. The awards provide up to $10,000 in research funding to residents and fellows. The aim of this program is to advance the experience and mentorship in clinical and translational research.
Dr. Zhou said she and her mentor faculty, Paul Fey, PhD, hope to enroll at least 50 patients, whose blood will be drawn and sent for cultures in the Nebraska Medicine Clinical Microbiology Laboratory. The S. epi isolates will go to the Nebraska Public Health Laboratory for whole-genome sequencing and bioinformatics analysis. Two experienced infectious disease physicians will review the cases and determine the likelihood of infection versus contamination based on the clinical picture.
“We will compare the whole-genome sequencing prediction to physician review results to see how well they correlate, if sequencing is useful to differentiate S. epi bloodstream infection from contamination,” she said.
This study has been recently accepted for publication in Infection Control and Hospital Epidemiology.
Dr. Zhou earned her medical degree in China in 2014 and her PhD at UNMC in 2019, followed by a postdoctoral fellowship at New York University from 2020 to 2023. She’ll finish her two-year fellowship here in June. Dr. Zhou hopes to find a position as clinical microbiology lab director at an academic institution, where she could combine clinical service with research and teaching.