Emmonsia Mold SpeciesEmmonsia species are causative agents of Adiaspiromycosis. (Information from www.doctorfungus.org @ 2005)
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Taxonomic Classifications
Kingdom:
Fungi
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Ecology
Emmonsia is a cosmopolitan filamentous fungus commonly isolated from soils and from numerous mammalian species, such as small rodents. It has the ability to produce a distinctive structure known as adiaspore at 37 – 40oC thus, considered as a dimorphic fungus as well. Emmonsia species is an occasional causative agent of animal and human infections. Emmonsia parva is known to be prevalent in Australia, Southwestern USA, and Eastern Europe while Emmonsia crescens has been reported worldwide.
Species
The genus Emmonsia currently consists of four species, namely: Emmonsia parva, Emmonsia parva var. crescens, Emmonsia parva var. parva, and Emmonsia pasteuriana. Emmonsia parva is occasionally referred to as Chrysosporium parvum.
Pathogenicity and Health Effects
Emmonsia species is the etiologic agent of adiaspiromycosis in animals and more rarely in humans and is described as asymptomatic pulmonary infection which may disseminate in immunocompromised patients, such as those with AIDS. The said infection develops after breathing in of Emmonsia conidia. Then, these conidia, which are also called as adiaspores, enlarge in the alveoli and hinder regular pulmonary functions. Additionally, adiaspores only remain at their primary implantation site and do not reproduce and eventually, become calcified and lead to a minimal reaction in the host tissue. Emmonsia parva var. crescens is the primary species isolated from humans while Emmonsia parva var. parva is mostly isolated from animals. Additionally, Emmonsia pasteuriana has recently been isolated from a cutaneous disseminated infection in an HIV – infected patient.
Macroscopic Appearance
Ø Growth rate is moderately rapid and colonies have glabrous to velvety texture; and Ø Surface colony color is white and may have buff to pale brown center and while cream to pale brown on the reverse.
Microscopic Appearance
Ø Hyaline septate hyphae, conidiophores, and aleuriconidia are present while adiaspores are only formed at 37 – 40oC in vivo or on blood or brain heart infusion agar in vitro; Ø Conidiophores are simple or sometimes branching at right angles; Ø Aleuriconidia are hyaline, unicellular, round in shape and lightly roughened, sessile or located on slender stalks, usually solitary or may form two to three – celled chains, and 2 - 5 x 2 - 4 µm in size; Ø The conidia tend to swell and give rise to adiaspores which are thick - walled, big conidia liberated at 37 - 40°C; Ø The only Emmonsia species which do not produce adiaspores is Emmonsia pasteuriana which only produces budding cell – like cells structures at 37oC on brain – heart infusion agar; Ø Adiaspores of the two varieties of Emmonsia parva may differ in size, structure and in their required temperature for their optimum growth; For Emmonsia parva var. parva, adiaspores are uninucleate, may reach 25 µm in vitro and 40 µm in vivo and are formed at 40oC while the adiaspores of Emmonsia parva var. crescens are multinucleate, may be bigger compared to those of Emmonsia parva var. parva and are formed at 37oC.
Laboratory Precautions
Only general laboratory precautions are required, no special safety measures needed.
Susceptibility
No
data available. |