Dimorphic fungi

Bifonazole represents the first topical broad spectrum antimycotic approved for once daily administration. Its in vitro activity appears equivalent to its structured relative clotrimazole, being effective against dermatophytes, other filamentous fungi, dimorphic ftingi and yeasts. 

In dimorphic fungi, the composition of constituent polysaccharides is sensitive to morphology and to the cultural conditions. These effects are accentuated in the case of Sporothrix schenckii, and 13C-n.m.r. spectroscopy can be used to detect individual polysaccharides in a qualitative way. The 13C-n.m.r. spectra of mannose-containing polysaccharides of ten Sporothrix schenckii and three Ceratocystis stenoceras species, grown under various conditions, were distinguishable in terms of the presence of signals,130 at 8C 103.3 to 103.7, which arose from 0-a-L-rhamnopyranosyl-(l- 2)-0-a-L-rhamnopyranosyl-(1— 3)-side-chains (14 C-l, 103.7 C-l, 96.8), and were not present in... 

Amphotericin B is used to treat systemic disseminated fungal infections caused by Candida spp., Cryptococcus neoformans, and the invasive dimorphic fungi Aspergillus spp., Histoplasma capsulatum, Coccidioides immi-tis, Blastomyces dermatitidis, and Sporothrix schenckii). Intravenous amphotericin B remains the treatment of choice for serious invasive fungal infections unresponsive to other agents. 

Significant drug interactions include cyclosporins (increased cyclosporine levels), phenytoin, rifampin, and rifabutin (decreased voriconazole levels). Because of its low toxicity profile, this drug may gain importance in the chronic treatment of infections with invasive dimorphic fungi and resistant Candida spp. 

Voriconazole is similar to itraconazole in its spectrum of action, having excellent activity against Candida sp (including fluconazole-resistant species such as C krusei) and the dimorphic fungi. Voriconazole is less toxic than amphotericin and is the treatment of choice for invasive aspergillosis. 

The major fungal opportunistic pathogens that affect immunocompromised hosts are the yeasts Candida and Cryptococcus, with the filamentous fungi Aspergillus and Fusarium and the dimorphic fungus Histoplasma also causing potentially fatal infections.4 Candida albicans... 

The molecular phylogeny and systematics of the fungi will be discussed elsewhere in this book [13]. A simple division of fungi with respect to clinical aspects is that into molds and yeasts, the former characterized by the formation of septate and nonseptate hyphae, the latter by an unicellular life cycle with reproduction mainly by budding. The so-called dimorphic fungi, such as Histoplasma... 

Characterization the immimocompetent host is infected by the dimorphic fungi as they change their morphological form patients usually get infected by inhalation of conidia restricted to certain geographic areas... 

The genus Ustilago is representative of this order. Ustilago species are commonly dimorphic phragmobasidial smut fungi parasitic on seeds and flowers of many cereals and grasses [380]. Smut spores may be inhaled and therefore may be isolated from sputum specimens. Based on partial sequences... 

Leclerc MC, Philippe H, Gueho E Phylogeny of dermatophytes and dimorphic fungi based on large subunit ribosomal RNA sequence comparisons. J Med Vet Mycol 1994 32 331-341. 

Nickerson KW, Atkin AL, Hornby JM. Quorum sensing in dimorphic fungi farnesol and beyond. Appl. Environ. Microbiol. 2006 72 3805-3813. 

For systemic treatment of fungal infections in dogs and cats, ketoconazole and fluconazole are available as tablets and oral suspensions, itraconazole as capsules, while miconazole and fluconazole are available as parenteral solutions. Even though ketoconazole is often effective, itraconazole may be the preferred azole for the treatment of systemic disease caused by dimorphic fungi (Blastomyces dermatitidis, Histoplasma capsulatum, Sporothrix schenckii). The activity of fluconazole against dimorphic fungi is limited to coccidioidal disease (Coccidioides immitis), but this azole penetrates the blood-brain barrier. 

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