Lab work in meningitis probe painstakingly slow

In row upon row of test tubes inside Vanderbilt University Medical Center's microbiology lab, culture samples from the spinal fluid of potential meningitis patients sit and develop.

Spores thrive and reproduce, but in many cases the pace is more like a tree than a weed. It can take up to a week for the first colored fuzz to appear. It can take six weeks before scientists are comfortable that the growth has provided enough evidence for a negative diagnosis.

And even then, nothing is certain.

Fungal meningitis is a moving target. The deadly disease is exceedingly rare. That's what makes this type of research so dynamic. Scientists across the country have been working overtime underneath biohazard hoods to perform daily diagnostic analysis and test potential treatments for the outbreak that has now infected 214 people in 15 states, causing 15 deaths.

Researchers expedite what they can, but the process takes diligence. What once may have appeared irrelevant in a petri dish or on a stained slide is now painstakingly noted — just in case it holds later significance. And every answer leads to more questions.

"On TV it happens in an hour," said Carol Rauch, associate medical director of Vanderbilt Pathology Laboratory Services. "In the clinical laboratory setting, it's not a test with an answer."

At Vanderbilt, a rainbow of different colored fungi grow in test tubes stored within a sealed room inside the microbiology lab.

Right now 700 cultures are growing in the incubator, 175 of which are samples from patients' spinal fluid. Among them is a cylinder boasting the fuzzy, powdery gray, blue-green mold aspergillus — one of the two fungi indicated as the contaminating cause of the current fungal meningitis outbreak.

Inside the tube, the fungus appears velvety — like a soft moss — but its potency caused one of the first fungal meningitis deaths in Tennessee. And it is in this lab that it grew from a sample of the sick patient's spinal fluid, alerting scientists first locally, and then nationally, to a potential medical and scientific anomaly.

The fluid, which when uninfected is clear and colorless, acts as a liquid cushion protecting the brain and spinal column from injury. Before this crisis, the microbiology lab at Vanderbilt may have received 10 spinal fluids a week. Now, it is receiving at least five a day, medical technologist Tonya Snyder said.

Pressure measured during the procedure is one of the most immediate indications of potential meningitis, as inflammation of brain tissue may obstruct normal fluid flow. There may also be immediate visual clues, such as cloudy or colored fluid.

But most of the evaluation is done in the lab. The samples of spinal fluid are studied for protein, glucose and blood cell counts, which can be done in a matter of hours.

Then the specimen undergoes microbiologic analysis, where part of the sample is put into culture tubes to see whether any infection, such as bacteria or fungi, grows. The growth process can take weeks. And once a fungus appears, the challenge becomes determining its type.

Tucked inside a Vanderbilt lab drawer is a copy of "Medically Important Fungi," one of the dozens of reference books used for analysis. Under her arm, Rauch carries another, "Identifying Filamenytous Fungi." Inside, blue sticky notes serve as bookmarks to entries on aspergillus and exserohilum — the second fungus now believed to be responsible for a majority of the meningitis cases in Tennessee.