Fungus that sparked deadly meningitis outbreak aggressively attacked the brainstem

The fungus behind a spate of deadly meningitis cases last year linked to medical clinics in Mexico was found to have aggressively attacked the base of patients’ brains, researchers said Wednesday in a report published in The New England Journal of Medicine.

Fungal meningitis was reported in as many as 24 patients from the United States who visited two medical clinics in Matamoros, Mexico. Many came from Texas. Twelve died.

All of the patients had undergone cosmetic procedures — such as breast implants, butt lifts or liposuction — that required epidural anesthesia. It was later discovered that the epidural was contaminated with a fungus called Fusarium solani; the epidural, experts said, introduced the fungus into the patients’ cerebrospinal fluid, a liquid found in and around the spinal cord and brain that provides nourishment and protection and removes waste.

In the report, researchers from the University of Texas System and the Centers for Disease Control and Prevention scrutinized the electronic health records, imaging and pathology reports of 13 of the patients. They found that the fungus, which has a predilection for sticking to blood vessels, was rampant in the vessel-rich brainstem.

“What we ended up seeing is, literally, this fungus eating through blood vessels and causing clotting as well,” said Dr. Luis Ostrosky, division director of infectious diseases at UTHealth Houston and one of the paper’s authors.

As a result, patients suffered strokes, brain hemorrhages and increased pressure within the brain as inflammation blocked the flow of the spinal fluid.

“Seeing how the brain stem was impacted in very specific ways, which were unexpected and unusual, is an important finding and potentially could help alert clinicians to future cases” and lead to better and quicker diagnosis and treatment, said Dr. Celeste Philip, the senior public health adviser of health and medical affairs at the American Public Health Association. Philip was not involved with the new report.

Getting treatment early is critical, said Dr. Katrina Byrd, an infectious disease expert and epidemic intelligence officer at the CDC. “If we can catch infection early, the length of the treatment is shorter and the effect of the infection on the body is less severe,” she said.

Many of the patients in the Matamoros outbreak were not evaluated and treated for a month or more after the onset of meningitis symptoms, such as chronic headache, light and sound sensitivity and fever. Some were turned away from emergency departments and were told that they probably had post-epidural headaches. Others, some without health insurance, ignored their symptoms.

Six of the surviving patients received an experimental antifungal drug late in the outbreak after it was discovered through lab tests that the fungal strain was resistant to current drugs, said Dallas Smith, an epidemiologist with the Mycotic Diseases Branch in the CDC’s National Center for Zoonotic and Emerging Infectious Diseases, who led the agency’s efforts on the outbreak. A seventh patient also received the drug but died.

He noted that it is difficult to grow the fungus in the lab from spinal fluid; the sample that was successfully cultured came from the brain of a patient who had died.

Survivors, as well as some who died, also received steroids for inflammation, shunts to divert backed-up spinal fluid and other advanced treatments to address the attack on the brainstem.

Contaminated epidural

It remains unclear exactly how the fungus entered the epidural solution at the Matamoros clinics, but the CDC has a theory. The morphine that was mixed with the anesthesia most likely was contaminated, said Smith.

Because of drug shortages, morphine is hard to come by in Mexico, and so the anesthesiologist, who moved between both clinics, likely purchased it on the black market, said Smith, who was an author on the new report.

Several weeks ago, the CDC was able to grow the Fusarium fungus from the spinal fluid of a patient in Tennessee and compare it to the fungus cultured last year from the brain autopsy. The two patients had each visited a different clinic, yet the strains were genetically almost identical. That finding supports the theory that the fungus was introduced into the epidural by contaminated morphine and not poor hygiene during surgery, Smith said.

Either way, the fungus was directly delivered into the epidural space of the spine, “and that’s why we got this devastating mortality rate,” he said.

An unusual outbreak, but not the last

Despite the unusual and severe nature of the outbreak, experts warned that there are likely more to come.

“This is probably not our last fungal outbreak,” said Ostrosky, who is also chief of infectious diseases and epidemiology at Memorial Hermann Health System in Houston. A similar outbreak occurred in Durango, Mexico, at the end of 2022.

Clinicians should ask patients with symptoms of meningitis, which can be caused by bacteria, a virus or fungi, about their recent medical history, said Smith.

“Do they have exposure to epidurals? Do they have a recent history of medical tourism?” Smith said. If the answers are “yes,” then the patients should be tested for fungal meningitis, he said.

Byrd offered several tips for people who are considering going abroad for medical treatment, where it can be less expensive than in the U. S. These include:

• See a health care provider at least four weeks in advance to discuss your plan of care when you return and to line up a specialist in advance for any complications.

• Consult a travel medicine specialist to make sure you have all needed vaccines.

• Research the medical facility to make sure it is accredited and the clinician to make sure they are licensed.

• Purchase travel insurance.

• Bring home your medical records from the foreign clinic,

• and never hesitate to inform your health care provider if you are feeling ill and be sure to mention that you received health care abroad.

“Even if you’re not having symptoms, a good plan of care is, upon your return, to check in with a health care provider,” Byrd said.

CORRECTION (Feb. 8, 2024, 4:05 p.m. ET): A previous version of this article misstated the number of surviving patients who received an experimental antifungal drug. It was six, not seven.

This article was originally published on NBCNews.com