Primarily saprophytic in nature, fungi of the genus Acremonium are a well-documented cause of mycetoma and other focal diseases. More recently, a number of Acremonium spp. have been implicated in invasive infections in the setting of severe immunosuppression. During the course of routine microbiological studies involving a case of fatal mycosis in a nonmyeloablative hematopoietic stem cell transplant patient, we identified a greater-than-expected variation among strains previously identified as Acremonium strictum by clinical microbiologists. Using DNA sequence analysis of the ribosomal DNA intergenic transcribed spacer (ITS) regions and the D1-D2 variable domain of the 28S ribosomal DNA gene (28S), the case isolate and four other clinical isolates phenotypically identified as A. strictum were found to have <99% homology to the A. strictum type strain, CBS 346.70, at the ITS and 28S loci, while a sixth isolate phenotypically identified only as Acremonium sp. had >99% homology to the type strain at both loci. These results suggest that five out of the six clinical isolates belong to species other than A. strictum or that the A. strictum taxon is genetically diverse. Based upon these sequence data, the clinical isolates were placed into three genogroups.

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A n IgG antibody to Aspergillus fumigatus was not present in the patient's serum, and Aspergillus fumigatus was not detected in either BAL sample by PCR. However, a serum Coccidioides IgG complement fixation titer was positive at 1:32. Coccidioides immitis/Coccidioides posadasii was isolated from culture of the BAL fluid and was also detected by a specific PCR assay. Treatment with fluconazole was initiated (1). The patient's lengthy history of pulmonary illness suggests that she had acquired her infection in Mexico or Arizona, but autochthonous coccidioidomycosis has also been reported in Washington State (2). Most coccidioidal pneumonia is self-limited, and fewer than 1% of patients develop chronic progressive pulmonary infections, which may be indistinguishable from other chronic fungal or mycobacterial infections (3). Diabetes mellitus is a risk factor for chronic infection. Radiologic manifestations of chronic disease include residual nodules, chronic cavities, persistent pneumonia with or without lymphadenopathy, pleural effusion, and regressive changes such as localized fibrosis, bronchiectasis, and calcification (4). The pulmonary imaging in this patient was not specific for Coccidioides infection; however, the presence of the air crescent sign in the dependent area of the cavitating lesion was not felt to be typical for an aspergilloma, and sparing of the lung apex reduced the likelihood of tuberculosis.Patients with suspected coccidioidomycosis should be evaluated with serologic testing. Isolation of Coccidioides species in culture can definitively establish the diagnosis. Direct sequencing from tissue samples is increasingly utilized. A noteworthy feature in this case is the presence of hyphal forms in the patient's respiratory tract. Coccidioides spp. are dimorphic fungi acquired by inhalation of spores, which replicate as spherules containing endospores in the host while forming hyphae in the environment. However, hyphal forms and arthroconidia (see Fig. 1C in the photo quiz) are occasionally seen in foreign-body-associated infections and in the lung cavities of patients with chronic infections (5). Although false-positive Aspergillus galactomannan assays have been described for patients with invasive infections caused by other fungi, including Penicillium spp., Cryptococcus neoformans, Magnusiomyces capitatus (Geotrichum capitatum), and Histoplasma capsulatum (6), to our knowledge this is the first report of a false-positive Aspergillus galactomannan assay in a patient with coccidioidomycosis.

In the original publication of the article, the GenBank Accession Number was misprinted as ON14059.The correct Accession Number is ON140595.The original article has been updated.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.