This doctor nearly lost her eye—until metagenomics uncovered a hidden infection
Industry Buzz
In infectious disease diagnostic testing, the goal of using metagenomics is to detect a pathogen that was not detected with conventional testing.
Daniel D. Rhoads, MD, FCAP, head of microbiology at the Cleveland Clinic's Main Campus
Laboratories that process samples using metagenomics will extract DNA from a sample and sequence it using high-throughput technology with the potential to diagnose over 1,000 different microorganisms.
Kenneth J. Taubenslag, MD, M.Phil, assistant professor of Ophthalmology & Visual Sciences at the University of Maryland
A 29-year-old doctor, Ellie Irwin of Bristol, England, experienced mysterious eye symptoms for over 5 years before doctors discovered the root cause.
Dr. Irwin dealt with ongoing inflammation and blurred vision in her right eye, which led to the development of a cataract. Frustrated, she even considered removing her eye. []
Basic tests said she was free from infection. So, Dr. Irwin and her doctors thought she could have an autoimmune condition, as eye inflammation can be present in certain diseases, like spondyloarthritis. []
She was taking steroid drops and immunosuppressants via intravenous transfusions—a treatment protocol that took up her time and energy and that ultimately didn’t work.
"It was completely dominating my life," she told the BBC. "I needed eye drops every single hour, and it was difficult to balance that alongside starting work as a junior doctor. My vision was really variable, and I would have some bad days.” []
Eventually, Dr. Irwin saw a team of specialists at Moorfields Eye Hospital in London, who used metagenomics to analyze the condition.
It turns out that Dr. Irwin had a rare bacterial infection called leptospirosis. The treatment? It was simple: antibiotics. []
Related: A routine beauty treatment caused one woman permanent eye damageWhat is metagenomics?
Metagenomics refers to the sequencing of all nucleic acid material present within a clinical sample. Its goal is to discover clinically relevant microbial information. [] In Dr. Irwin’s case, metagenomics stepped in to identify exactly which infection she had.
“In infectious disease diagnostic testing, the goal of using metagenomics is to detect a pathogen that was not detected with conventional testing,” Daniel D. Rhoads, MD, FCAP, who serves as the head of microbiology at the Cleveland Clinic's Main Campus, explains to MDLinx.
“Metagenomic testing can be a powerful tool, but it can also be very challenging to interpret the results accurately. For example, a negative result does not rule out the possibility of infection, and positive results are often due to microbes that are not causing the patient’s disease,” Dr. Rhoads cautioned.
Kenneth J. Taubenslag, MD, M.Phil, assistant professor of Ophthalmology & Visual Sciences at the University of Maryland, says he’s familiar with metagenomics.
“In ophthalmology, this can be especially helpful when there is high suspicion for infectious uveitis, but a precise diagnosis remains elusive,” Dr. Taubenslag says.
When cultures aren’t offering up information, he says the team will send a sample of eye fluid for next-generation sequencing.
“Laboratories that process samples using metagenomics will extract DNA from a sample and sequence it using high-throughput technology with the potential to diagnose over 1,000 different microorganisms,” he explains.
Related: 'Blind Mind’s Eye': Rare visual impairment sparks promising researchPotential limitations
“Although many research laboratories perform metagenomic testing, no metagenomic tests are FDA-approved or FDA-cleared for use as a diagnostic tool,” Dr. Rhoads says. “In my experience, infectious disease specialists, in collaboration with pathologists or clinical microbiologists, work together to determine what testing might be most useful in challenging clinical cases.”
It’s not exactly accessible, either. “Diagnostic metagenomic testing is very expensive and is typically only used on very sick hospitalized patients in exceptional circumstances,” Dr. Rhoads adds.
The good news is that the field is expanding. “Interesting cases, like the current leptospirosis case, provide exciting anecdotes that help us to recognize novel diagnostic tools…and to dream of how we might be able to use metagenomic methods more routinely in the future,” says Dr. Rhoads.