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Category: Clinical Microbiology
Fusarium and Other Opportunistic Hyaline Fungi*, Page 1 of 2
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This chapter focuses on those fungi that grow in tissue in the form of hyaline or lightly colored septate hyphae. These fungi include Fusarium and other hyaline fungi. Disease caused by hyaline fungi is referred to as hyalohyphomycosis. Hyaline fungi described in this chapter include the anamorphic, asexual hyphomycetes and coelomycetes, as well as homothallic ascomycetes that produce sexual structures and ascospores in culture. Phenotypic/morphologic identification of hyaline moulds is based on methods of conidiogenesis and spore formation; however, accurate species-level identification frequently requires DNA sequence data from one or more informative loci. Molecular phylogenetic analysis has revealed that several Fusarium morphospecies actually represent species-rich species complexes, including the following six species complexes: F. solani, F. oxysporum, F. fujikuroi, F. incarnatum-F. equiseti, F. chlamydosporum, and F. dimerum. Fusarium species are cosmopolitan soil saprobes that can cause toxicosis or infection in humans. A frequent infection in immunocompetent humans is keratitis resulting from trauma or contamination of contact lenses/solutions. Severe disseminated fusarial infections are seen in patients with hematological malignancy or an allogenic hematopoietic stem cell transplant. The portal of entry is unknown in most cases of invasive fusarial infections; however, inhalation of airborne conidia appears to be the most common mode of transmission. Other hyaline fungi can cause human infection as well, ranging from cutaneous to disseminated systemic invasive infections. In general, the recovery of a hyaline fungus from a normally sterile site and microscopic evidence of tissue damage provide the most convincing evidence of invasive disease.
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(A) Member of the FSSC. Microconidia are borne on long monophialides (thin arrow). Macroconidia borne in the aerial mycelium are also present (thick arrow). (B) Member of the FOSC bearing microconidia on short monophialides. A few macroconidia are also present. (C) Chains of microconidia produced by Fusarium verticillioides (formerly Fusarium moniliforme) in the FFSC. (D) Fusarium proliferatum in the FFSC. Note polyphialides (arrows) with more than one opening not delimited by a septum. Truncate conidia that have been borne in chains as well as false heads are also present. (E) Macroconidia of Fusarium dimerum in the FDSC. Note that conidia are two celled and that the septum is in the middle. (F) Macroconidia of Fusarium delphinoides in the FDSC. Note that the septum in two-celled conidia is off-center (thick arrow) and that a macroconidium with three septa (thin arrows) and four cells is also present. (G) Colony of Achaetomium strumarium showing yellowish surface mycelium and pink pigment on cornmeal agar after 5 weeks. (H) An isolate of Gymnascella hyalinospora described in reference 137 was glabrous and sterile when grown on potato dextrose agar for 15 days at 30°C. doi:10.1128/9781555817381.ch120.f1
(A) Member of the FSSC. Microconidia are borne on long monophialides (thin arrow). Macroconidia borne in the aerial mycelium are also present (thick arrow). (B) Member of the FOSC bearing microconidia on short monophialides. A few macroconidia are also present. (C) Chains of microconidia produced by Fusarium verticillioides (formerly Fusarium moniliforme) in the FFSC. (D) Fusarium proliferatum in the FFSC. Note polyphialides (arrows) with more than one opening not delimited by a septum. Truncate conidia that have been borne in chains as well as false heads are also present. (E) Macroconidia of Fusarium dimerum in the FDSC. Note that conidia are two celled and that the septum is in the middle. (F) Macroconidia of Fusarium delphinoides in the FDSC. Note that the septum in two-celled conidia is off-center (thick arrow) and that a macroconidium with three septa (thin arrows) and four cells is also present. (G) Colony of Achaetomium strumarium showing yellowish surface mycelium and pink pigment on cornmeal agar after 5 weeks. (H) An isolate of Gymnascella hyalinospora described in reference 137 was glabrous and sterile when grown on potato dextrose agar for 15 days at 30°C. doi:10.1128/9781555817381.ch120.f1
(A) Same isolate of Gymnascella hyalinospora as in Fig. 1H turned yellow on oatmeal agar, with clusters of ascospores after 15 days at 30°C. (B) Ascospores of Gymnascella hyalinospora observed by scanning electron microscopy. Magnification, ×6,000. (C) Perithecium of a species of Microascus. (D) Brown ascospores of Cephalotheca foveolata that formed after 8 weeks on carnation leaf agar at 25°C. (E) Phialemonium-like anamorph of Cephalotheca foveolata showing adelophialides (reduced phialides without a septum) and ellipsoidal conidia. (F) Tissue section stained with Gomori methenamine silver stain showing monokaryotic (clampless) hyphae of Schizophyllum commune in a pulmonary fungus ball. (G) Schizophyllum commune in slide culture preparation showing clamp connections and narrow pegs or spicules (arrows). Magnification, ×580. (H) Dikaryotic culture of Schizophyllum commune showing development of gilled fruiting bodies on potato dextrose agar after 7 weeks in the light. doi:10.1128/9781555817381.ch120.f2
(A) Same isolate of Gymnascella hyalinospora as in Fig. 1H turned yellow on oatmeal agar, with clusters of ascospores after 15 days at 30°C. (B) Ascospores of Gymnascella hyalinospora observed by scanning electron microscopy. Magnification, ×6,000. (C) Perithecium of a species of Microascus. (D) Brown ascospores of Cephalotheca foveolata that formed after 8 weeks on carnation leaf agar at 25°C. (E) Phialemonium-like anamorph of Cephalotheca foveolata showing adelophialides (reduced phialides without a septum) and ellipsoidal conidia. (F) Tissue section stained with Gomori methenamine silver stain showing monokaryotic (clampless) hyphae of Schizophyllum commune in a pulmonary fungus ball. (G) Schizophyllum commune in slide culture preparation showing clamp connections and narrow pegs or spicules (arrows). Magnification, ×580. (H) Dikaryotic culture of Schizophyllum commune showing development of gilled fruiting bodies on potato dextrose agar after 7 weeks in the light. doi:10.1128/9781555817381.ch120.f2
(A) Setal hyphae of Inonotus tropicalis in a slide culture preparation on potato flakes agar at 10 days and 25°C. Bar, 20 μm. (B) Colony of Chrysosporium zonatum on potato dextrose agar after 14 days at 37°C. (C) Conidia of Chrysosporium zonatum formed on short curved stalks. (D) Rough-walled stipe, metulae, and phialides of Rasamsonia argillacea. Note also that conidia are initially cuneiform (wedge shaped). Bar, 10 μm. (E) Conidia of Myceliophthora thermophila in various stages of maturity. Mature conidia are dark and rough. Bar, 10 μm. (F) Culture of three different isolates of Onychocola canadensis after 5 weeks on Mycosel agar. (G) Setae (appendages) of Onychocola canadensis. (H) Colony of Paecilomyces variotii on potato dextrose agar after 7 days. doi:10.1128/9781555817381.ch120.f3
(A) Setal hyphae of Inonotus tropicalis in a slide culture preparation on potato flakes agar at 10 days and 25°C. Bar, 20 μm. (B) Colony of Chrysosporium zonatum on potato dextrose agar after 14 days at 37°C. (C) Conidia of Chrysosporium zonatum formed on short curved stalks. (D) Rough-walled stipe, metulae, and phialides of Rasamsonia argillacea. Note also that conidia are initially cuneiform (wedge shaped). Bar, 10 μm. (E) Conidia of Myceliophthora thermophila in various stages of maturity. Mature conidia are dark and rough. Bar, 10 μm. (F) Culture of three different isolates of Onychocola canadensis after 5 weeks on Mycosel agar. (G) Setae (appendages) of Onychocola canadensis. (H) Colony of Paecilomyces variotii on potato dextrose agar after 7 days. doi:10.1128/9781555817381.ch120.f3
(A) Colony of Purpureocillium lilacinum on potato dextrose agar after 14 days. (B) Verticillate conidiophores of Purpureocillium lilacinum bearing whorls of phialides. Bar, 10 μm. (C) Yellowish colony of Phialemoniopsis curvata on potato flakes agar after 14 days at 25°C. (D) Colony of Phialosimplex caninus with yellow diffusible pigment on potato dextrose agar after 21 days at 30°C. (E) Conidia of Phialosimplex caninus borne in long chains or heads from simple basally inflated phialides. Bar, 2 μm. (F) Rough-walled conidia in chains formed on annellides in Scopulariopsis brevicaulis. Note the branched conidiogenous apparatus. Magnification, ×580. (G) Colony of Trichoderma longibrachiatum on potato dextrose agar after 4 days at 37°C. Note that the plate was inoculated on one side. (H) Green, oval conidia of Trichoderma longibrachiatum. Bar, 10 μm. doi:10.1128/9781555817381.ch120.f4
(A) Colony of Purpureocillium lilacinum on potato dextrose agar after 14 days. (B) Verticillate conidiophores of Purpureocillium lilacinum bearing whorls of phialides. Bar, 10 μm. (C) Yellowish colony of Phialemoniopsis curvata on potato flakes agar after 14 days at 25°C. (D) Colony of Phialosimplex caninus with yellow diffusible pigment on potato dextrose agar after 21 days at 30°C. (E) Conidia of Phialosimplex caninus borne in long chains or heads from simple basally inflated phialides. Bar, 2 μm. (F) Rough-walled conidia in chains formed on annellides in Scopulariopsis brevicaulis. Note the branched conidiogenous apparatus. Magnification, ×580. (G) Colony of Trichoderma longibrachiatum on potato dextrose agar after 4 days at 37°C. Note that the plate was inoculated on one side. (H) Green, oval conidia of Trichoderma longibrachiatum. Bar, 10 μm. doi:10.1128/9781555817381.ch120.f4
Classification of Fusarium infections a
Classification of Fusarium infections a
Key phenotypic features of clinically significant Fusarium species a
Key phenotypic features of clinically significant Fusarium species a
Key phenotypic features of selected hyaline moulds a
Key phenotypic features of selected hyaline moulds a