Blog | Tuesday, July 8, 2014

DNA sequencing for fever of unknown origin


Amidst the weekly deluge of health and medicine stories, one from last week stood out.

Too often, news reports of “the latest and greatest” in medicine are overhyped. Here, the news wave was started by a case report that appeared in the New England Journal of Medicine. The two best media accounts that explain what happened are here and here.

A quick summary: a 14 year-old Wisconsin boy lay in a coma in a hospital intensive care unit. The diagnosis was encephalitis, inflammation of the brain. All of the standard tests of blood, urine, spinal fluid, and even a brain biopsy (!) did not yield a cause of the illness.

This is not unusual. In both persistent fevers (medicalese: “Fever of Unknown Origin”) and severe bloodstream infections (medicalese: “Sepsis”) we are unable to find the exact pathogen more than half the time. Without knowing the precise cause, we often carpet bomb patients with several antibiotics and other medications trying to save them. But when the cause is known, we can target the treatment more precisely, greatly increasing the chance of recovery and diminishing the likelihood of harm.

The doctors in Wisconsin sent a sample of the boy’s blood and spinal fluid to a lab in California that performed “Next Generation Sequencing,” which involves using massive computational power to essentially compare genetic material in the fluids to thousands of known genetic sequences of different bacteria, viruses and fungi. They found a strong positive match to a bacterium known as Leptospira santarosai, which amazingly, is fully sensitive to good old penicillin.

Voila! The kid got better.

The innovation here is being able to rapidly pattern-match DNA sequences instead of the time-honored way we usually plod along, trying to ‘culture’ microorganisms in incubators (essentially growing them out of patients’ blood, urine, or spinal fluid samples).

I’m usually skeptical of claims made about technological innovation in health care, but to me this story has the hallmarks of a true game changer.

This post by John H. Schumann, MD, FACP, originally appeared at GlassHospital. Dr. Schumann is a general internist. His blog, GlassHospital, seeks to bring transparency to medical practice and to improve the patient experience.