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Understanding the Relationship Between the Microbiome and Bloodstream Infection in Leukemia Patients

By Dr. Stephanie McMahon | Ph.D. Candidate in Genetics

Acute myeloid leukemia is the most prevalent form of leukemia in adults in the United States. Typically, it is treated with cytotoxic chemotherapy. However, during this treatment, patients are at a higher risk for bloodstream infections (BSIs) and subsequent mortality due to weakened mucosal lining and decreased immune responses.

Previous studies have shown that bacteria from the gastrointestinal microbiome — the community of microorganisms (such as fungi, bacteria and viruses) and their genomic content that exist in a particular environment — spreading to other organs, like the liver and kidneys, are a significant source of BSIs. When bacteria indigenous to one environment move into another (called “bacterial translocation”), they travel across the gut mucosa to extraintestinal sites and tissues that are normally sterile.

Prior to bacteria translocation, there are often increased levels of infectious organisms in the gastrointestinal tract. This research aimed to understand how the abundance, or “dominance,” of a particular genera or species of microbe relative to others in the oral cavity and gut relate to bloodstream infection incidence in acute myeloid leukemia patients. Moreover, this research also aimed to determine if the infectious agent and the presence of antibiotic resistance determinants could be detected in the stool via digital droplet PCR (ddPCR) at the time of infection (prior to culture).

These findings indicate that monitoring the oral and gastrointestinal microbiome is crucial for detecting both life-threatening pathogens and the genes that confer antibiotic resistance before a bloodstream infection occurs. These findings have the potential to improve the timing and tailoring of antibiotic treatment strategies for patients at high-risk of infection due to chemotherapy. Other researchers on this project included graduate student Samantha Franklin and faculty member Dr. Jessica Galloway-Peña.

These findings were published in Microbiology Spectrum.

Filling The Gap: Down Syndrome, Bone Health, And Fracture Healing

Filling The Gap: Down Syndrome, Bone Health, And Fracture Healing

By Kirby Sherman | Ph.D. candidate in Biomedical Sciences
Department of Veterinary Physiology & Pharmacology

Down syndrome (DS), the most common birth defect in the United States, alters human development and leads to a variety of clinical issues, including low bone mass and strength. Because people with DS are living longer, more active lives, their risk of bone fracture has increased.

However, there is a significant gap in knowledge regarding DS and fracture healing, and it remains unknown if people with DS are able to heal fractures. This observation of the lack of research surrounding DS and bone health was first made in the laboratory of Dr. Larry Suva, in the School of Veterinary Medicine & Biomedical Sciences Department of Veterinary Physiology & Pharmacology. Indeed, the risk of fractures is a major health concern for the DS community and can severely impact their quality of life.

Due to the increased risk resulting from decreased bone mineral density observed in DS people, our work sought to understand how DS impacts the ability to heal a fracture. Ultimately, we determined that when individuals with DS fracture a bone, that bone is unlikely to heal. We also discovered the reason why these bones fail to heal (called non-union), namely inflammation and a defect in bone repair.

Importantly, fractures that fail to heal can be fatal, even in young people with no previous health concerns. With this new awareness of the problem, we hope there will be more widespread adoption of measures to increase bone strength, more careful monitoring when fractures do occur, and that physicians and others will consider the bone health of people with DS a priority for their care.