Paecilomyces Mold SpeciesThe U.S. Government's Occupational Safety and Health Administration [OSHA] classifies Paecilomyces species as an allergen and irritant and a cause of Hypersensitivity Pneumonitis and Dermatitis.
Paecilomyces species are causative agents of Hyalohyphomycosis. (Information from www.doctorfungus.org @ 2005)
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Taxonomic Classifications
Kingdom:
Fungi
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Ecology
Paecilomyces is a cosmopolitan filamentous fungus which is isolated from soil and decaying plant material and often associated in decay of food products and cosmetics. Certain species of Paecilomyces parasitize insects. Paecilomyces is usually considered as a contaminant as well as a rare pathogenic fungus in humans.
Species
The genus Paecilomyces contains several species. The most common are Paecilomyces lilacinus and Paecilomyces variotii. The colony morphology and microscopic features of the different Paecilomyces species aid in distinguishing the species from one another. Thermophilicity is another helpful feature that helps in species identification. Paecilomyces crustaceus and Paecilomyces variotii are both thermophilic and grow well at temperatures as high as 50°C and possibly at 60°C.
Pathogenicity and Health Effects
Paecilomyces species can cause various infections in humans which are referred to as paecilomycosis. The infection ranges from corneal ulcer to keratitis, and to endophthalmitis which is due to the growth of Paecilomyces following an extended contact lens use or ocular surgery. Additionally, Paecilomyces is among the emerging causative agents of opportunistic mycoses in immunocompromised hosts wherein direct cutaneous inoculation may lead to these infections and may involve almost any organ or system of human body. Other infections which have been reported due to Paecilomyces include soft tissue, pulmonary, and cutaneous infections, cellulitis, onychomycosis, sinusitis, otitis media, endocarditis, osteomyelitis, peritonitis, and catheter - related fungemia. Paecilomyces species can also cause allergic alveolitis which is an allergic disorder.
Macroscopic Appearance
Ø Growth rate is rapid and colonies are flat, powdery or velvety in texture and mature within three days; Ø The surface colony color is initially white becoming yellow, yellow – green, yellow – brown, olive – brown, pink, or violet, depending on the species while reverse is dirty white, buff or brown; and Ø A sweet aromatic odor may be observed with older cultures.
Microscopic Appearance
Ø Septate hyaline hyphae, conidiophores, phialides, conidia, and chlamydospores are present; Ø Conidiophores are often branched and carry the phialides at their tips, and with size ranging from 3 – 4 x 400 - 600 µm; Ø Phialides are thin, swollen at their bases, elongated at their tips, and are usually grouped in brush – like structures at the ends of the conidiophores; Ø Conidia are oval to fusoid in shape, unicellular, hyaline to darkly colored, smooth or rough, and appear in long chains; and Ø Chlamydospores are sometimes present.
Laboratory Precautions
General laboratory precautions are required, no special safety measures needed.
Susceptibility
Limited data are available. Data on Paecilomyces fumosoroseus, Paecilomyces javanicus, Paecilomyces lilanicus, Paecilomyces marquandii, and Paecilomyces variotii are the ones included. Except for strains of Paecilomyces lilanicus, the MICs of amphotericin B tended to be very low while the MICs of flucytosine tended to be very high except for strains of Paecilomyces variotii. For all species tested, fluconazole yielded considerably high MICs. Itraconazole and ketoconazole MICs were lowest for Paecilomyces variotii compared to other species. Voriconazole has been tested against Paecilomyces lilanicus and Paecilomyces variotii and has yielded low MICs for both of these species. Appeared active in vitro against Paecilomyces were posaconazole, the novel triazole UR-9825, and terbinafine. On the other hand, caspofungin lacks positive response against Paecilomyces lilanicus but was active in vitro against Paecilomyces variotii.
Amphotericin B and flucytosine has been successfully used in treatment of some paecilomycosis cases due to Paecilomyces lilanicus regardless of high MICs in vitro. Additionally, caspofungin combined with itraconazole has also been found to be effective in treating infection caused by Paecilomyces lilanicus.
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