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WEDNESDAY, June 26 (HealthDay News) -- Autopsies conducted on victims of last year's outbreak of meningitis linked to steroid shots show that a fungus in the injections made its way to the base of the brain.
The outbreak in the United States began last fall among people who got the steroid shots in their spines in the hopes of easing back pain.
However, a fungus contaminating the injections triggered meningitis in 745 people across 20 states and killed 58, according to the U.S. Centers for Disease Control and Prevention.
The source of the contaminated methylprednisolone steroid was the New England Compounding Center in Massachusetts, which has now closed. More than 13,000 people received the potentially tainted steroid injections.
Most cases of infection were caused by a mold called Exserohilum rostratum, which rarely infects people. In this study, researchers reviewed the cases of 40 patients who were given injections of the steroids. Of those patients, 16 died and all except two of the fatal cases were diagnosed with meningitis.
Autopsies revealed extensive bleeding and tissue decay around the base of the brain and blood clots in the basilar artery, which is one of the arteries that supplies the brain with blood, according to the study published June 26 in The American Journal of Pathology.
Tissue samples from infected patients showed inflammation of thin membranes lining the brain and blood vessel walls within the brain. Abnormalities were detected around brain blood vessels, and fungus was found around and within the walls of brain arteries. Only one patient had fungus deep inside the brain tissue itself.
Fungus was not found in tissue samples taken from the heart, lung, liver or kidney.
The autopsy findings support "the hypothesis that [the fungus] migrates from the lumbar spine to the brain through the cerebrospinal fluid," Jana Ritter, a veterinary pathologist with the Infectious Diseases Pathology Branch of the CDC, said in a journal news release.
For more on fungal infections, visit the U.S. Centers for Disease Control and Prevention.