DESCRIPTIONS OF MEDICAL FUNGI

Descriptions of Medical Fungi 63
Synonymy: Entomophthora coronata (Costantin) Kevorkian.
The species of the genus Conidiobolus produce characteristic multinucleate primary
and secondary (replicative) conidia on top of unbranched conidiophores. Each
subspherical conidium is discharged as a result of the pressure developed within the
conidium, and each bears a more or less prominent papilla after discharge (King 1983).
The genus contains 27 species, however only Conidiobolus coronatus, C. incongruus
and C. lamprauges have been reported as causative agents of human and animal
infection. A morphological identification key for clinical isolates was given by Vilela et
al. (2010).
RG-2 organism.
Conidiobolus coronatus (Costantin) Batko
Morphological Description: Colonies of C. coronatus grow rapidly and are flat,
cream-coloured, glabrous becoming radially folded and covered by a fine, powdery,
white surface mycelium and conidiophores. The lid of the petri dish soon becomes
covered with conidia, which are forcibly discharged by the conidiophores. The colour
of the colony may become tan to brown with age. Conidiophores are simple forming
solitary, terminal conidia which are spherical, 10 to 25 µm in diameter, single-celled
and have a prominent papilla. Conidia may also produce hair-like appendages, called
villae. Conidia germinate to produce either: (1) single or multiple hyphal tubes that
may also become conidiophores which bear secondary conidia; or (2) replicate by
producing multiple short conidiophores, each bearing a small secondary conidium.
C. coronatus is commonly present in soil and decaying leaves. It has a worldwide
distribution especially in tropical rain forests of Africa. Human infections are usually
restricted to the rhinofacial area. However, there are occasional reports of dissemination
to other sites. All human infections have been confined to the tropics.
References: Emmons and Bridges (1961), King (1983), McGinnis (1980), Rippon
(1988), Kwon-Chung and Bennett (1992), de Hoog et al. (2000, 2015), Ellis (2005a).
Conidiobolus coronatus culture showing satellite colonies formed
by germinating conidia ejected from the primary colony.