Microbiome: Pathology's New Frontier

Pathologists are increasingly optimistic about the potential of the human microbiome to help guide diagnosis and monitoring of chronic diseases. The microbiome includes a vast array of bacteria, viruses and fungi living throughout the body that are critical for preserving human health and preventing disease.

The human body has roughly equal numbers of human and microbial cells. The majority of microbes in the microbiome are bacteria, primarily living in the oral cavity and gut. Studies show that good health depends on having a healthy microbiome. Microbes in the microbiome influence many functions in the human body.

Research shows that an unhealthy gut microbiome can contribute to obesity, diabetes, cancer, heart disease and several other chronic conditions. Inflammation causes most diseases and gut health determines inflammation levels in the body.

Speaking at the annual meeting of the College of American Pathologists, James Versalovic, MD, PhD, FCAP, pathologist in chief at Texas Children's Hospital and professor of pathology and immunology at Baylor College of Medicine, said he believes that microbiome-based diagnostics soon will be used to enable pathologists to stratify patients for treatment in selected diseases.

"By knowing which microbes are present, pathologists will be able to classify patients in ways that are similar to stratifying patients with cancer or other chronic diseases," said Versalovic. The challenge, he added, is determining if changes in microbial composition or function are the cause or result of disease.

Versalovic explained that microbiome analysis has made strides in gastroenterology using fecal samples to diagnose and monitor enteric infections and chronic conditions such as irritable bowel syndrome and colitis.

"Pathologists are playing a key role in diagnosing infectious diseases and evaluating the microbiome community for clues regarding which treatments will be most effective," Versalovic said. "As we continue to advance our knowledge of the human microbiome in chronic disease, pathologists will be able to recommend medications, and perhaps diet and lifestyle changes, based on microbiome analysis."

Versalovic foresees a starring role for the microbiome in oncology. "The microbiome could be valuable in assessing colorectal cancer risk," he said. "When pathologists examine biopsied tissue, they also could check the microbiome in the same sample or in body fluids obtained in the same procedure. Microbiome-based lab testing also could help in monitoring the likelihood of treatment success or patient responses to chemotherapy and immunotherapy.

"I'm convinced that the human microbiome will be an important component for a more holistic approach for health and disease management," said Versalovic. "Pathologists now must carefully consider agree on how we can apply knowledge of the microbiome in future practices."

About the College of American Pathologists

As the world's largest organization of board-certified pathologists and leading provider of laboratory accreditation and proficiency testing programs, the College of American Pathologists (CAP) serves patients, pathologists, and the public by fostering and advocating excellence in the practice of pathology and laboratory medicine worldwide. For more information, read the CAP Annual Report at cap.org.