Exserohilum rostratum was the major cause of an outbreak of fungal infections linked to injections of contaminated methylprednisolone acetate. Because almost 14,000 persons were exposed to product that was possibly contaminated with multiple fungal pathogens, there was unprecedented need for a rapid throughput diagnostic test that could detect both E. rostratum and other unusual agents of fungal infection. Here we report development of a novel PCR test that allowed for rapid and specific detection of fungal DNA in cerebrospinal fluid (CSF), other body fluids and tissues of infected individuals. The test relied on direct purification of free-circulating fungal DNA from fluids and subsequent PCR amplification and sequencing. Using this method, we detected Exserohilum rostratum DNA in 123 samples from 114 case-patients (28% of 413 case-patients for whom 627 samples were available), and Cladosporium DNA in one sample from one case-patient. PCR with novel Exserohilum-specific ITS-2 region primers detected 25 case-patients with samples that were negative using broad-range ITS primers. Compared to fungal culture, this molecular test was more sensitive: of 139 case-patients with an identical specimen tested by culture and PCR, E. rostratum was recovered in culture from 19 (14%), but detected by PCR in 41 (29%), showing a diagnostic sensitivity of 29% for PCR compared to 14% for culture in this patient group. The ability to rapidly confirm the etiologic role of E. rostratum in these infections provided an important contribution in the public health response to this outbreak.
In late September 2012, the Centers for Disease Control and Prevention (CDC) began to investigate an outbreak of fungal meningitis associated with epidural injections of contaminated methylprednisolone acetate solution purchased from a single compounding pharmacy (1-5). By 15 January 2013, 678 cases of fungal infections, including meningitis, spinal, paraspinal, or peripheral joint infections, had been reported from 19 states, and 44 people had died. Although Aspergillus fumigatus was isolated from the index patient (1), and several fungal species were identified in patients during the outbreak, the vast majority of laboratory-confirmed infections were caused by Exserohilum rostratum, which was detected in cerebrospinal fluid (CSF) and tissues of patients (3, 6).E. rostratum (teleomorph Setophaeria rostrata) is a dematiaceous (brown-black) filamentous fungus, which is common in the environment and occasionally causes opportunistic infections in humans (7-9). In healthy individuals, exposure to E. rostratum can cause allergic sinusitis or cutaneous and subcutaneous infections (7, 10, 11). Invasive fungal infections due to E. rostratum are rare and limited to persons with severely impaired immune systems (7, 10, 12). To our knowledge, no cases of fungal meningitis or encephalitis due to this fungus had been described prior to this outbreak. In addition, no genome or animal models had been developed to study E. rostratum, which also complicated the deve...