Chrysosporium species

Chrysosporium species (Mould)

Note:  Chrysosporium is another species I’ve been holding onto in hopes of obtaining additional specimens (strains) and taking better photographs.  I’m really not satisfied with what I’ve taken to date but here they are for what they’re worth.

Ecology:

Chrysosporium is a ubiquitous, cosmopolitan fungus.  It is a rather common saprobe (living on dead organic matter).

Pathology:

 A number of species are keratinophiles and although they may be isolated from skin and nails, they are generally considered to be contaminants.

Rare reports of systemic infections in immunocompromised hosts have been published; however, their importance in the disease process remains uncertain.  Skin infections of snakes, iguanas, crocodiles and dogs have been more commonly reported.

Colony Morphology:

Growth is described as slow to moderately rapid, reaching maturity within about one week.

Colony morphology may be quite variable between isolated species.  Texture is powdery to cottony to woolly.  The colony may remain compact or be spreading and may show further variation by being flat or raised.  Pigmentation is usually white but may vary from pale yellow, pink, pale brown or weakly orange.  The reverse is most often white but may be yellow, tan or brownish.

 Chrysosporium species - on Saboraud Dextrose Agar (SAB), 14 days at 30ᵒC. (Nikon)

Chrysosporium species - after 21 days on SAB, at 30ᵒC. (Nikon)

Microscopic Morphology:

Chrysosporium produces septate, hyaline hyphae.  Conidia (aleurioconidia) often appear to be minimally differentiated from the hyphae and may appear to form directly on the hyphae (sessile).  Conidia more often form at the ends of simple or branched conidiophores of varying length. Conidiophores may be ramified, forming tree-like structures.  Conidia are usually one-celled (2 – 9 X 3 – 13 µm).  They appear as clavate (club shaped) with the apex (top) rounded while the base being broad and flat.  Remnants of the attaching structure may, for a time, remain attached.  Conidial walls are thin-walled and the exterior is usually smooth.  Intercalary conidia are sometimes formed and may appear as a cylindrical or barrel shaped structure or may be seen as a bulge on only one side of the hyphae.

Chrysosporium is the asexual form of Nannizziopsis vriesii and therefore ascocarps (large, sexual fruiting bodies) may occasionally be seen in fresh cultures.

Chrysosporium species - initial look at a slide culture at low power.  Can't see much detail but I just liked the look of this photo.

(250X, LPCB*, DMD-108) 

* Lactophenol Cotton Blue Stain

Chrysosporium species - another slide culture.  Picture a coverslip on a block of agar about a square centimeter in size.  All along the four edges of the coverslip, the fungus is growing.  Gently removing the coverslip from the agar block has some of the fungus adhering to the glass coverslip.  Placing the coverslip onto a microscope slide that has a drop of Lactophenol Cotton Blue Stain on it.  The right side of the above photo shows the edge that was against the agar block from which the fungus grew.

This slide shows the extensive branching mycelia with free and bound conida throughout.

(250X, LPCB, DMD-108)

Chrysosporium species - hyphae and conidia still attached to the conidiophores and hyphae.

(250X, LPCB, DMD-108)

Chrysosporium species - Conidiophores may be 'ramified', forming tree-like structures. 

(400X, LPCB, DMD-108)

Chrysosporium species - conidia frequently stain more intensely than do the conidiophores which bear them or the hypha themselves.

(100X, LPCB, DMD-108)

Chrysosporium species - conidia may form short chains or develop as intercalary conidia (within the hyphae).  Here (arrow) appears to show such a short chain or possibly intercalary conidia.

(400X, LPCB, DMD-108)

 Chrysosporium species - another example of what appears to be a chain of conidia or alternatively might be described as intercalary (within the hypha) conidia.

(400+10X, LPCB, DMD-108)

Chrysosporium species - intercalary conidia are sometimes formed and may appear as a cylindrical or barrel shaped structure or may be seen as a bulge on only one side of the hyphae (arrows).

(1000X, LPCB, DMD-108)

 Chrysosporium species -typical appearance.

(400X, LPCB, DMD-108)

Chrysosporium species - as above.

(400X, LPCB, DMD-108)

Chrysosporium species - another example.

(400X, LPCB, DMD-108)

Chrysosporium species

(400X, LPCB, DMD-108)

 Chrysosporium species - sometimes it is difficult to tell whether there is a chain of conidia, a true intercalary conidium or whether there are just overlapping conidiophores which give the appearance of chaining.  (400+10X, LPCB, DMD-108)

Chrysosporium species

(400+10X, LPCB, DMD-108)

 Chrysosporium species - conidia are rather thin walled (see center right of photo)

(1000X, LPCB, DMD-108)

 Chrysosporium species - oversaturation of the blue could not be effectively corrected with photo editing programs - then again, I just like this shot!

(1000X, LPCB, DMD-108)

Chrysosporium species - conidia are usually one-celled and about (2 – 9 X 3 – 13 µm).

(1000X, LPCB, DMD-108)

 Chrysosporium species - conidia are clavate (club shaped) and have a round apex (far end) and a broad, flat base where attached to the conidiophore.  Sources state that remnants of the attachment point (conidiophore) may remain attached to free conidia, however, I have not observed this in the photos I've taken.  The separation of the conidia from the conidiophore appears to be quite clean.

Here also you can see that the conidiophores are minimally differentiated from the hypha itself.  There is no uniquely recognizable,or elaborate structure to the conidiophores  Conidiophores appear to have variable lengths.   Condia appear to arise directly from the hyphae (sessile) and also may be on longer, simple or branched conidiophores.

(1000X, LPCB, DMD-108)

Chrysosporium species - rather delicate looking conidiophores - like fine pedicile-like strands attaching the conidia to the hyphae.  (1000X, LPCB, DMD-108)

Chrysosporium species - again, fine structured conidiophores attached to the tear-drop or clavate (club shaped) conidia.  (400X, LPCB, DMD-108)

Chrysosporium species - conidia on conidiophores arising from all sides of the hyphal element.

(1000X, LPCB, Nikon)

Chrysosporium species - Last photo.  Teardrop or clavate shaped conidia attached to septate hyphae via delicate, minimally differentiated conidiophores.

(1000X, LPCB, Nikon)

Physiology:

Chrysosporium is resistant to cycloheximide and therefore may be isolated on selective media used for primary isolation of dermatophytes.

Chrysosporium is urea positive.

Notes:  Chrysosporium species may develop branches diverging at 45ᵒ angles whereas the branches formed by dermatophytes are borne at angles closer to 90ᵒ.

Chrysosporium may produce conidia as short, terminal chains which are not seen in dermatophytes.

Young cultures of Chrysosporium may be confused with Blastomyces dermatitidis however they are not thermally dimorphic as is Blastomyces.

Chrysosporium may also be confused with Emmonsia parva, however Chrysosporium does not produce adiaconidia at 37ᵒC and some species fail to grow at 37ᵒC.

Chrysosporium can be distinguished from Sporotrichum species as the latter spreads rapidly to cover the entire media surface, fails to grow on cycloheximide, and usually forms abundant arthroconidia which may break from the hyphae to form clusters.

One source states that species which produce short terminal chains of conidia, grouped in small tree-like clusters,  are now considered to belong to the genus Geomyces rather than Chrysosporium.

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Epidermophyton floccosum

Epidermophyton floccosum (mould/dermatophyte)

Note:  While I've had photos of Epidermophyton floccosum for some time now, I've never been satisfied with the quality of the microphotographs I've taken.  I remain unsatisfied here.  The photos for this and every other post contained in this blog were taken by myself on my own time, before or after regular work hours.  Unfortunately I find myself so busy at times that my own projects take a distant back seat.  Primary cultures sometimes may become contaminated or overgrown.  Isolates may revert to a sterile form on repeated subculture, as in this case, before sufficient study.   While I've obtained several isolates over the years, E.floccosum always seems to defeat my best efforts to obtain those "text book" quality photos.  Time is running out...

Ecology: 

Epidermophyton floccosum is a cosmopolitan (worldwide distribution) anthropophilic (man is the primary host & reservoir) dermatophyte [i] .  A once though related species, Epidermophyton stockdaleae has been determined to be a synonym for Trhycophyton ajelloi which exhibits no known pathogenicity to humans or animals

Pathogenicity:

E.floccosum causes tinea pedis (athlete’s foot), tinea cruris (groin infections or “jock-itch), and tinea corpis (body infections), and to a lesser extent onychomycosis (nail infections). Skin infections are also known as “ring-worm” though there is no ‘worm’ involved.  Infection with E.floccosum may be transmitted in gym facilities where unprotected feet may share a common floor. E.floccosum rarely infects the scalp and does not infect hair or hair follicles.

Macroscopic Morphology:

E.floccosum exhibits moderate growth, becoming mature in about 10 – 14 days.  Surface colonies (media influenced) have been described as mustard yellow or yellowish brown to olive-grey (khaki) in colour.  Colonies can be powdery, velvety or felty in texture and acquire a folded appearance as growth progresses.  After prolonged incubation, sterile floccose (hairy) white mycelia may cover the colony.  The reverse has been described as ochre, mustard-yellow to yellow-brown and even orange in colour.

 

E.floccosum -colony heaped up at center on SAB after 2 weeks at 30ᵒC (Nikon)

E.floccosum -colony on SAB (Saboraud Dextrose Agar) after 2 weeks at 30ᵒC (Nikon)

 E.floccosum -colony on SAB after 3 weeks at 30ᵒC (Nikon)

  E.floccosum -another colony on SAB after 3 weeks at 30ᵒC (Nikon)

   E.floccosum -yet another colony on SAB after 5 weeks at 30ᵒC.

Note: white floccose patches beginning to develop. (Nikon)

E.floccosum -colony on SAB, 30ᵒC after repeated subcultures has developed white floccose patches which are areas of sterile hyphae.  (Nikon)

 

Microscopic Morphology:

E.floccosum has septate hyphae however microconidia are not produced which differentiates it from the other genera of dermatophytes.  Macroconidia develop as lateral or terminal outgrowths from mature hyphae and initially lacks a basal septum. Rather thin walled macroconidia (10 -40 µm X 6 – 12 µm) contain 2 to 5 cells can occur singly or in characteristic clusters.  As the culture ages, macroconidia may transform into chlamydoconidia (chlamydospores) so they are best observed earlier in growth. The macroconidia are smooth walled, and clavate (club shaped) with a blunt tip.  This also differentiates it from Microsporum and Trichophyton.  (Again, see endnote 1).

Note: 

Stock cultures are best maintained on SAB media with 3 – 5% sodium chloride.  This may reduce or prevent the isolate from becoming sterile.

E.floccosum - a first look at low power.

(100X, LPCB, DMD-108) 

E.floccosum - Slightly higher magnification reveals the macroconidia more clearly.

(250X, LPCB, DMD-108)

E.floccosum - as above, numerous club shaped macroconidia are clearly seen.

(250X, LPCB, DMD-108)

E.floccosum - club shaped macroconidia with internal septations.

(1000X, LPCB, DMD-108)

E.floccosum - club shaped macroconidia with internal septations.

(1000X, LPCB, DMD-108)

E.floccosum - club shaped macroconidia with internal and basal septations.

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

E.floccosum - again, club shaped macroconidia with internal septations.  My isolates tended to produce single macroconidia over the grouped macroconidia where several macroconidia crowd each other growing out from the same area of the hypha.

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

 E.floccosum - a single macroconidium.  Note that in this and other microphotographs in of E.floccosum, there are no microconidia.The lack of microconidia is one feature which distinguishes E.floccosum from other dermatophytes.

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

  E.floccosum - several macroconidia.

 (1000X, LPCB, DMD-108)

 E.floccosum - a single mature macroconidium.

 (1000+10X, LPCB, DMD-108)

  E.floccosum - a single mature macroconidium with a curious little kink in it's side.

 (1000+10X, LPCB, DMD-108)

 E.floccosum - macroconidium measures 35.18 µm in length.

This was obviously an adhesive tape preparation which may trap air bubbles or even reveal uneven adhesive application which may detract from the photograph.

 (1000+10X, LPCB, DMD-108)

 

E.floccosum - club shaped macroconidia.  I have this photo recorded as taken at 400X which is confirmed by the micron bar in the upper right.  However, the macroconidia seem extremely large for this magnification if compared to previous photos at 1000X.  The same goes for the photo which follows.  Curious...

(400X, LPCB, DMD-108)

E.floccosum - numerous club shaped macroconidia as above.

 (400X, LPCB, DMD-108)

 

 E.floccosum - this photo was taken from a culture that was just over three weeks old.  Numerous roundish chlamydospores have developed.  Again, compare the micron bar in the upper right to the previous photo which shows identical magnification yet the macroconidia vary greatly is size.

(400X, LPCB, DMD-108)

 

 E.floccosum - macroconidia and chlamydospores present in this adhesive tape preparation

  (1000X, LPCB, DMD-108)

 E.floccosum - macroconidia on prolonged culture. Some sources say that arthroconidia may also develop, however, I have never observed them in my older E.floccosum cultures.

(500X, LPCB, Nikon)

  E.floccosum - finger-like group of macroconidia.

(1000X, LPCB, Nikon)

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[i] Dermatophyte – fungi which thrive on keratin for growth therefore they primarily infect skin, hair and nails depending on the genera and species.  Epidermophyton, Microsporum and Trichophyton are dermatophytes.  Epidermophyton had macroconidia that are clavate (club shaped) while Microsporum produces fusiform (spindle shaped) macroconidia and Trichophyton possesses cylindrical or ‘cigar-shaped’ macroconidia.  E.floccosum does not produce microconida which also serves to differentiate it from the other dermatophytes.

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