Exophiala jeanselmei

Exophiala jeanselmei -Mitosporic fungi; Hyphomycetes

Note:  With the advent of molecular testing, some sources are stating that Exophiala jeanselmei should more correctly be referred to as the Exophiala jeanselmei complex.  See explanation at the bottom of this post.

Also: Compare Exophiala jeanselmei with Exophiala dermatitidis elsewhere in this blog by clicking here.

Ecology:

Exophiala species can be found worldwide and may be isolated from soil, decaying wood and fresh water sources. 

Pathogenicity:

Exophiala jeanselmei may be an agent of mycetoma[i] and phaeohyphomycosis[ii] has also been implicated as an agent of back grain mycetoma and chromoblastomycosis[iii].  While occurring worldwide, some evidence suggests that infections, particularly neurotropic infections, may be more prevalent in East Asia.

Macroscopic Morphology:

Colonies are initially moist and yeast-like in texture; however they soon form a velvety surface due to the production of aerial mycelia.  Some isolated can remain yeast-like without further development.

The colony can be brownish-black to greenish-black with the reverse being black in colour.

Exophiala jeanselmei grows slowly, maturing within about 14 days at 25ᵒC to 30ᵒC.

Exophiala jeanselmei on SAB after incubation for 3 weeks at 30ᵒC.

While this isolate matured rather quickly, compared to the "up to 14 days" stated by some sources, the colony expanded outward slowly. (Nikon)

 Exophiala jeanselmei on SAB after incubation for ~3 weeks at 30ᵒC.

Heaped up, folded appearance.  (Nikon)

 

Microscopic Morphology:

Young cultures with budding yeast-like cells may eventually develop septate hyphae.  Hypha, initially hyaline (clear) become pale brown to olivaceous as the colony ages.  The conidiogenous annellophores (structure producing annelloconidia) are slender, sometimes branched, and narrow towards the apex (tip).  The smooth annelloconidia (2.5 – 6.0 µm X 1.2 – 2.5 µm) are oval or ellipsoidal in shape and if undisturbed, accumulate in clusters around the tip and upper sides of the annellide.  Potato Dextrose Agar (PDA) or Corn Meal Agar (CMA) may enhance conidia production, however all the photos on this post were taken from isolates grown on Sabouraud Dextrose Agar (SAB) with copious conidia produced.

Exophiala jeanselmei - mycelial growth adhering to small piece of agar from a slide culture after 4 days of growth.  (250X, LPCB, DMD-108)

Exophiala jeanselmei - small clusters or balls of conidia become evident, dispersed along the mycelia at this magnification. (250X, LPCB, Nikon)

Exophiala jeanselmei -Individual conida can now be made out at this magnification.

(400X, LPCB, DMD-108)

Exophiala jeanselmei -septate hyphae appear as if vacuolated.  Conidiogenous structures (annellophores) do not appear to be highly differentiated from the hyphae themselves and can be intercalary (along the hyphae) or terminal (at the end of the hyphae).

(1000X, LPCB, DMD-108)

Exophiala jeanselmei -as above, with typical accumulation of the oval to ellipsoidal annelloconidia around the top, and along the sides of the annellophore.

(1000X, LPCB, DMD-108)

Exophiala jeanselmei -again, intercalary, and terminal production of annelloconidia.

(1000X, LPCB, DMD-108)

Exophiala jeanselmei -and another.

(1000+10X, LPCB, DMD-108)

Exophiala jeanselmei -Both clusters of conidia and individual conidia can be seen at the tips of the annellophores.  (1000, LPCB, DMD-108)

Exophiala jeanselmei -Branched annellophore with (annello)conidia.

(1000+10X, LPCB, DMD-108)

Exophiala jeanselmei - and another...

(1000+10X, LPCB, DMD-108)

Exophiala jeanselmei - ditto, as above.

(1000+10X, LPCB, DMD-108)

Exophiala jeanselmei -branched conidiophore at various stages of conidia production.

(1000+10X, LPCB, DMD-108)

Exophiala jeanselmei -okay, too many photos of the same structures!!

(1000+10X, LPCB, DMD-108)

Exophiala jeanselmei -the annellophore appears undifferentiated from the hyphae from which it arises.  Nice photo showing the annelloconidia accumulated around the apex of the annellophore from which they were produced.  Conidia are single-celled with the darkly staining band across the center of the conidia not being a septum. Also visible on many of the conidia is the remnants of a fringe, the scar that remains from where they were attached to the conidiophore.  This represents a specific method of reproduction and fringe or scar (annellide) is why we specify the conidiophore as an annellophore, and the conidia as an annelloconidia.  (1000+10X, LPCB, DMD-108)

 

Exophiala jeanselmei -as the colony matures, the hypha become pigmented which gives the colony its distinctive colour. (1000X, LPCB, DMD-108)

Exophiala jeanselmei -as above, just another view,

(1000X, LPCB, DMD-108)

Exophiala jeanselmei -an interesting shot showing the annellophore rising upwards from it's parent hyphae with the annelloconidia clustered about the apex.  Almost three-dimensional.

(1000X, LPCB, DMD-108)

Exophiala jeanselmei -copious amounts of conidia are produced.

(1000X, LPCB, DMD-108)

Exophiala jeanselmei -as previously stated, the darkly staining band across the center of the annelloconidium is not a septum.  The single-celled annelloconidia have the fringe or scar which remains at one end of the cell which is why the conidia are specifically referred to as annelloconidia.

(1000+10X, LPCB, DMD-108)

Exophiala jeanselmei -conidium germinating.

(1000X, LPCB, DMD-108)

Exophiala jeanselmei -annelloconidia (1000+10X, LPCB, DMD-108)

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[i] Mycetoma is a chronic, progressively destructive morbid inflammatory disease usually of the foot but any part of the body can be affected. Infection is most probably acquired by traumatic inoculation of certain fungi or ‎bacteria into the subcutaneous tissue. (WHO)

[ii] Phaeohyphomycosis is a heterogeneous group of mycotic infection caused by dematiaceous fungi whose morphologic characteristics in tissue include hyphae, yeast-like cells, or a combination of these. (Wikipedia)

[iii] Chromoblastomycosis is a chronic fungal infection of the skin and the subcutaneous tissue caused by traumatic inoculation of a specific group of dematiaceous fungi. (Medscape)

Note:  As with most fungi, speciation of the genus Exophiala is undergoing change brought about by molecular analysis.  Some sources are now referring to the ‘Exophiala jeanselmei complex’.

Isolates from the United States that in the past had been identified as E. jeanselmei based on morphologic and physiologic characteristic have been shown by molecular methods to be mostly two newly named species closely related to E.jeanslemei, i.e. Exophiala oligosperma and Exophiala xenobiotica.  A lower percentage were found to belong to several other species of Exophiala.  The precise species in the complex can only be determined by molecular testing.

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Scopulariopsis brumptii

Scopulariopsis brumptii (Mould/Fungus)

Compare this species to Scopularis brevicaulis.

Ecology:  A cosmopolitan fungus (found just about everywhere), particularly in soil and in household dust.

Pathogenicity: Scopulariopsis brumptii is rarely implicated in disease; however, as with many other ‘non-pathogenic’ fungi, they may be considered opportunists and may be increasingly found as the cause of pulmonary (lung) infections in severely immunocompromised patients.  Encountered in the laboratory as a possible contaminant, they must be distinguished from more pathogenic fungi.

Macroscopic Morphology:  S.brumptii is a moderately rapid grower, usually maturing within about 5 days.  Surface growth may initially be whitish, then darkening from a light grey to a sepia-grey (reddish overtones) or fuscous (darker brown-grey).  One source described the colour as that of cigarette ash.  The grey overtones distinguish it from the cinnamon, tan or buff brown colour of Scopulariopsis brevicaulis.  The texture is described as velvety to powdery.

Scopulariopsis brumptii - Sabouraud-Dextrose Agar

(SAB, 12 Days, 30^oC, Nikon)

Microscopic Morphology:  S.brumptii produces septate hyphae that are hyaline when young but darkens as it matures. Conidiogenous (conidia producing) cells develop from the hyphae and can appear singly or in brush-like arrangements.   These conidiogenous cells are more specifically referred to as annellides as they produce conidia (annelloconidia) in succession, each leaving a ring-like collar on the annellide when the annelloconidia is released.   The annellides (5 µm – 10 µm X 2.5 µm to 3.5 µm) are somewhat flask-shaped, with a swollen base which tapers near the apex, however they are generally more cylindrical that those of S.brevicaulis.  The annelloconidia (4.0 µm – 5.25 µm X 3.5 µm – 4.5 µm) in size and although they can be smooth, the texture is usually described as finely roughened.  They are usually pyriform (pear-shaped), dark brown in colour and have a flattened or truncated base where once attached to the annellide.  The annellations (scar/ring) produced by S.brumptii may not be very conspicuous.  Annelloconidia are produced in loose chains from the apices of the annellides.

Scopulariopsis brumptii - darkly pigmented annelloconidia.

(KOH, 400X, Nikon)

Scopulariopsis brumptii -hyaline hyphae become pigmented as are the ellipsoidal annelloconidia.

(KOH, 1000X, Nikon)

Scopulariopsis brumptii - conidiogenous cells develop from the hyphae either singly or in brush-like arrangements.  These annellides produce the oval or ellipsoidal, darkly pigmented annelloconidia.

(KOH, 1000+10X, DMD-108)

 Scopulariopsis brumptii - an annellide is seen in the center of the photo extending from the hyphae.  The "three-fingered" brush-like arrangement at the apex has anelloconidia still attached and some which have been released.  (KOH, 1000+10X, DMD-108)

Scopulariopsis brumptii-  appear to be two single annellides, with annelloconidia being produced at the apex.  (KOH, 1000X, Nikon)

Scopulariopsis brumptii -the hyphae is septate and has produced a single annellide, bearing a single annelloconidium, at the center of the photo. (KOH, 1000X, Nikon)

Scopulariopsis brumptii -two brush-like arrangements of the annellides of S.brumptii are seen here in the center-left of the photo.  Numerous annelloconidia, both attached and free are seen.

(LPCB, 1000X, DMD-108)

Scopulariopsis brumptii - two bunches of annellides (the right one more brush-like than the left) are seen in the center of the photo.  Pigmented annelloconidia are seen at the apex.

(LPCB, 1000X, DMD-108)

Scopulariopsis brumptii -More brush-like annellides showing their arrangement and attatchment of annelloconidia.  (LPCB, 1000X, DMD-108)

Scopulariopsis brumptii - another branching annellide, thinned out a bit so the arrangement of the annellides are more easily seen.  The ring or collar is clearly visible on the annelloconidium seen at the lower middle of the photo.  It appears as a scar or flattened base where the annelloconidium was once attached to the annellide.   (LPCB, 1000X, Nikon)

Scopulariopsis brumptii -okay, too many photos, but what else am I going to do with them?

Hyphae, annellide & annelloconidia extending from the tips.

(LPCB, 1000X, DMD-108)

Scopulariopsis brumptii -ditto.  Lots of annelloconidia produced by this brush-like structure.

(LPCB, 1000+10X, DMD-108)

Scopulariopsis brumptii -two single annellides seen extending from the hyphae traversing the center of the photo.  Each has an annelloconidium still attached to the apex.  Look closely at the darkly pigmented mature annelloconidia and you will see the collarette (annellide ring) on many.

(LPCB, 1000+10X, DMD-108)

Scopulariopsis brumptii -a poorer example of the photo explanation above.  Two single annellides producing annelloconidia.  Many more single annellides are present in S.brumptii cultures than in S.brevicaulis cultures where the arrangements are primarily brush-like.

(LPCB, 1000X, DMD-108)

Scopulariopsis brumptii -again, as above, single, rather than brush-like arrangements might be seen more frequently in S.brumptii, than in S.brevicaulis.

(LPCB, 1000X, DMD-108)

Scopulariopsis brumptii -ditto - more single, rather than brush-like annellides may be seen in S.brumptii cultures.  (LPCB, 1000X, DMD-108)

Scopulariopsis brumptii -and a single annellide with an attached annelloconidium seen in the center of the photo.  A single free annelloconidium is seen in the upper left-third of the photo - the annellide ring or collarette visible at the bottom.  (LPCB, 1000+10X, DMD-108)

Scopulariopsis brumptii - a crowded photo showing at least two brush-like arrangements of annellides within a 'sea' of pigmented annelloconidia.

(LPCB, 1000X, DMD-108)

Scopulariopsis brumptii -oh, what the heck! -here's one more.  A brush-like arrangement of annellides and darkly pigmented, oval to ellipsoidal annelloconidia.

(LPCB, 1000+10X, DMD-108)

Note: Scopulariopsis species may show variable sensitivity to cycloheximide and therefore may or may not grow on Mycosel/Dermasil® agar.

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