The predominance of E. rostratum in the outbreak influences these recommendations. Although this organism has been identified in most culture-positive cases, there are caveats. The diagnostics are insensitive (culture), not yet validated (polymerase chain reaction), and applied in a context in which several microbial causes are possible. Although not validated on CSF, tests to detect microbial antigens, such as the galactomannan enzyme immunoassay, may be helpful to enhance sensitivity to detect additional cases of Aspergillus infection (6). The utility of (1-3)-β-D-glucan testing is also unclear, although this detects more fungi. Although the CDC does not recommend routine use of either antigen assay, we believe that clinicians should consider them when available to provide information about the full breadth of fungal organisms involved in the outbreak. They should not be done in lieu of either culture or polymerase chain reaction.