CDC Scientists Unravel Fungal Outbreak Associated With Steroid Injections
Findings suggest black mold targeted base of the brain (June 26)
Investigators at the Centers for Disease Control and Prevention (CDC) describe pathologic findings from 40 case reports of fungal infection in patients who had been given contaminated epidural, paraspinal, or intra-articular steroid injections and correlate these findings with clinical and laboratory data. The report, published in the September issue of the American Journal of Pathology, alerts clinicians and the general public to the dangers of contaminated epidural injections.
In September 2012, the CDC began hearing reports of fungal meningitis in patients following epidural steroid injections. By June 2013, 745 people had confirmed infections and 58 had died, making it the largest reported outbreak of infections associated with epidural and intra-articular injections.
After intensive investigation, the contamination was traced to more than 17,000 vials from three contaminated lots of preservative-free methylprednisolone acetate (MPA) originating from a single compounding pharmacy. More than 13,000 people were injected with the potentially contaminated drug. Most cases were attributable to Exserohilum rostratum, a dark-colored environmental mold that rarely infects humans.
Researchers report that of the 40 cases reviewed, 16 were fatal, and all except two fatal cases had a clinical diagnosis of meningitis. Autopsy examination showed extensive hemorrhage and necrosis around the base of the brain and thrombi involving the basilar arterial circulation.
Tissue specimens from infected individuals showed inflammation of the leptomeninges (the thin membranes lining the brain) and blood vessel walls within the brain. Distinctive abnormalities were observed around blood vessels, and fungus was found around and within arterial walls. Interestingly, fungus deep within the brain tissue itself was found in only one case.
Similar pathologic findings were seen at the epidural injection site. Fungus was not found in tissue samples taken from the heart, lung, liver, or kidney.
The investigators wondered why fungus injected in the spinal region should target the base of the brain.
“The observation of abundant fungi in the perivascular tissues, but relatively low numbers of fungi inside blood vessels, suggests migration of fungus into, rather than out of, vessels at this location. This supports the hypothesis that Exserohilum migrates from the lumbar spine to the brain through the cerebrospinal fluid with subsequent vascular invasion, rather than migration through the vasculature,” suggests Jana M. Ritter, DVM, a veterinary pathologist at the CDC’s Infectious Diseases Pathology Branch.
Source: Elsevier; June 26, 2013.