New gene tests for germs quickly reveal source of infections

Brian Jetter was on life support, a healthy 40-year-old suddenly battling pneumonia and sepsis, and a slew of tests had failed to find the cause.

Mystery illnesses like this kill thousands of people each year when germs can't be identified fast enough to reveal the right treatment. Now genetic tests are helping to solve these cases.

One finally was used to search Jetter's blood for bits of non-human genetic material from viruses, fungi and the like. It detected unusual bacteria that probably got into the Connecticut man's lungs when he choked and accidentally inhaled bits of a burger weeks earlier.

With the right medicine, he recovered and went home to his 5-year-old son.

"I realized how fragile life is," Jetter said. "No matter how healthy you are, the smallest microbe can destroy you."

Doctors routinely use genetic tests to spot inherited diseases and guide cancer treatment. But using them to detect infectious diseases is so new that few doctors and even fewer patients know they're available. A study of one test is published in Thursday's New England Journal of Medicine.

They are modernizing a field long overdue for an overhaul.

To identify bacteria, labs still rely on century-old techniques from Louis Pasteur — putting a few drops of blood or other sample in a lab dish and waiting days or sometimes weeks to see what germs grow. To test for a virus, a doctor usually has to guess what the patient is sick with. Testing for a fungus or some other things can take a long time.

Several companies and university labs now offer gene-based tests on blood or spinal fluid. Once fragments of foreign DNA or other genetic material are found, their code is analyzed, or sequenced, to identify bacteria, viruses, fungi and parasites causing sepsis, meningitis, encephalitis and...