Schlechtendahl (1824) emend. Snyder & Hansen (1940)

Macroscopic morphology

Macroscopic morphology may vary significantly on different media, and descriptions here are based upon growth on potato flakes agar at 25°C with on/off fluorescent light cycles of approximately 12 hours each. Rapid growth. Colonies are initially white, becoming tinged with salmon and lavender at maturity. Lavender to purple reverse. Salmon to orange sporodochia may be present [2202], [1630].

Microscopic morphology

Hyphae are septate and hyaline. Conidiophores are short (when contrasted with those of F. solani) and simple (usually not branched). Macroconidia usually produced abundantly, slightly sickle-shaped, thin-walled, with an attenuated apical cell and a foot-shaped basal cell. They are three to 5-septate measuring 23-54 x 3-4.5 µm. Microconidia are abundant, mostly non-septate, ellipsoidal to cylindrical, slightly curved or straight, 5-12 x 2.3-3.5 µm occurring in false heads (a collection of conidia at the tip of the phialide) from short monophialides. Chlamydoconidia are present and often abundant, occurring singly and in pairs [2202], [1630].

Special notes

While F. solani is the most common clinical isolate, Fusarium oxysporum appears to be the second most common species recovered [69]. It has been reported in skin and nail infections [1961], in subcutaneous disease [140], in a neutropenic child managed with granulocyte colony-stimulating factor [1025], in a disseminated infection in hemophagocytic lymphohistiocytosis [43], and in a fatal case involving a cross reaction with a pan-Candida genus probe. O’Donnell et al. reported it to be a genetically diverse human pathogenic species best described as a Fusarium oxysporum species complex. Concordant results from phylogenetic analysis of multilocus DNA sequence data and amplified fragment length polymorphisms showed that a geographically widespread clonal lineage comprised greater than 70% of all clinical isolates investigated, including strains investigated from a pseudoepidemic involving bronchial lavage isolates in a San Antonio hospital, and from water systems in hospitals in Houston, Baltimore, and Seattle [1666]. The species is usually easily identified by its lavender color on potato dextrose agar, its short monophialides, and microconidia formed only in false heads.

FTL* in vitro susceptibility data

2.0 µg/ml=6 >8.0 µg/ml=4 2.0 µg/ml=3
4.0 µg/ml=1 4.0 µg/ml=1
8.0 µg/ml=2 8.0 µg/ml=1
>8.0 µg/ml=1
Drug/N AMB/9 ITRA/4 VORI/6
MIC Range 2.0-8.0 >8.0 2.0->8.0

* Fungus Testing Laboratory unpublished data (NCCLS M38-A)