Unidentified Mould No. 2 -Challenge

I've had a tremendous amount of fun working with, and learning about the moulds posted here.  However, all things do come to an end as does this blog, and so I will leave this last one with you as a challenge.  Have some of your own "fun with microbiology" and let me know what you think the name of this mould should be.

It appeared as a plate contaminant on an un-inoculated plate of laboratory media.  While I took numerous photos, I did not follow through sufficiently to determining an identification.

Macroscopic Morphology:

-exhibited rapid growth on Sabouraud Dextrose Agar at 30^oC

-the isolate developed a short, 'fuzzy' surface

-colour was a grey-brown to a dark brown with a lighter coloured outer fringe

-the reverse was dark brown 

-I did not test the growth at 37^oC or above so this remains unknown.

 Unidentified mould - after 7 days on Sabouraud Dextrose Agar (SAB or SDA) at 30^oC (Nikon)

 

Microscopic Morphology:

-isolate developed septate, branched hyphae

-conidia developed directly from the hyphae (sessile) or from short stalks that appeared somewhat 'inflated' where the attached to/supported the conidium

-these conidia (?) were rather large, up to 10 µm in diameter.  Some appeared intercalary and perhaps were chlamydospores (?)

-spiral hyphae were occasionally observed

 Unidentified mould - a first look at the edge of a slide culture does not reveal much detail.

(100X, LPCB, DMD-108)

 Unidentified mould - at a slightly higher magnification conidia closely attached to the parent hyphae are evident.  (250X, LPCB, DMD-108)

Unidentified mould - younger, immature conidia retain the lactophenol cotton blue (LPCB) stain while the maturing conidia begin to develop a dark pigment.

(400X, LPCB, DMD-108)

 

Unidentified mould - immature conidia (blue) & maturing (dark) conidia occur in about equal numbers in this photo.

(400X, LPCB, DMD-108)

Unidentified mould - darkly pigmented sessile conidia seen along the hyphae.  Some younger (blue staining) conidia still seen closer to the ends of the hyphae.

(400X, LPCB, DMD-108)

 

Unidentified mould - as above

(400X, LPCB, DMD-108)

Unidentified mould - large numbers of conidia produced.

(400X, LPCB, DMD-108)

Unidentified mould -as above

(400X, LPCB, DMD-108)

Unidentified mould -sympodial growth pattern (arrow) ?  Further explanation follows further below.

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

Unidentified mould -a round conidium attached to the hypha by a short stalk, wider at the conidium than at the hypha.  (1000X, LPCB, DMD-108)

Unidentified mould -large, immature conidia attached to hyphae

(1000X, LPCB, DMD-108)

Unidentified mould - rather large conidia measuring up to 10 µm in diameter.  Note the base still attached to the one free conidium.  (1000X, LPCB, DMD-108)

Unidentified mould -spiral hyphae were regularly seen.

(1000X, LPCB, DMD-108)

Unidentified mould -conidia at different stages of maturity.  Note the attachment of the dark conidium  near center left of the photo.  It appears to still be attached by its inflated base or stalk.

(1000X, LPCB, DMD-108)

Unidentified mould - not a good photo -Why did I include this?

(1000X, LPCB, DMD-108)

 

Unidentified mould - two conidia attatched to or growing within? the hypha

(1000X, LPCB, DMD-108)

Unidentified mould -septate, branching hyphae with terminal and sessile conidia.

(1000X, LPCB, DMD-108)

Unidentified mould -large terminal oval conidium (chlamydospore?) seen in center of photo.  Immediately behind it there is a branch with a basal septum supporting a slightly out of focus conidium.  (1000X, LPCB, DMD-108)

Unidentified mould - just left of center, is what appears to be an intercalary conidium (chlamydospore).  That is, it appears to be in the middle of, and continuous with the hypha and not attached to it.  (1000X. LPCB, DMD-108)

Unidentified mould -conidia attached directly to the hyphae (sessile), on short, somewhat inflated stalks, and one near center-right on a longer simple stalk (or branch?)  Septations in the hyphae clearly visible.  (1000X, LPCB, DMD-108)

Unidentified mould -another photo as above.  A couple of the conidia appear to have a concave dimple.  Curious.  (1000X, LPCB, DMD-108)

Unidentified mould -and because 'more is better', here is another photo showing different stages of maturity and attachment.  (1000X, LPCB, DMD-108)

Unidentified mould -septate hyphae with sessile conidia.

(1000X, LPCB, DMD-108)

Unidentified mould - growth pattern of hyphae suggests sympodial growth (see next slide).  Pigment or stain may be exuded by the hyphae.  (1000X, LPCB, DMD-108)

Growth pattern of Sympodial vs Monopodial

Unidentified mould -Sessile conidium - resting right on the hypha.

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

Unidentified mould -you may remember this photo from earlier in this post, however, here is a closer look at the central dark conidium and the short inflated base attaching it to the broken hypha.  A younger, ellipsoidal conidium appears in the lower left.  Note too the rather thick-walled appearance of the round conidium in the upper left.

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

Unidentified mould

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

 Unidentified mould -a photo showing many of the features mentioned previously.  Conidia (chlamydospores) appear to be intercalary, withing the hypha.  Suggestions of sympodial growth pattern.  Large ellipsoidal terminal conidium appears to have a septum (arrow), dividing it into two compartments.  (1000X, LPCB, DMD-108)

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Trichophyton mentagrophytes Complex

Trichophyton mentagrophytes Complex (Fungus, Dermatophyte)

Ecology:  T.mentagrophytes is recognized as having two variants.  Anthropophilic isolates prefer man to animals while the zoophilic isolates primarily infect animals.  Small rodents appear to be the primary reservoir for the animal variety.  Trichophyton mentagrophytes is a cosmopolitan fungus (found everywhere).

Macroscopic Morphology:  T.mentagrophytes exhibits moderately rapid growth and matures within 6 – 10 days.  Sources have previously described anthropophilic isolates having a downy, powdery or even fluffy texture while zoophilic isolated were more granular in appearance.  Colonies may vary in colour from white to cream or yellowish.  The reverse also can vary from yellow to reddish brown to brown or ochre, depending on isolate and medium.

 Trichophyton mentagrophytes -5 days growth on SAB at 30^oC

 Trichophyton mentagrophytes - 14 days growth on SAB at 30^oC

Microscopic Morphology:  Trichophyton mentagrophytes produces septate hyphae from which branched conidiophores extend.  Sessile (not on stalk) microconidia are produced in rather dense, grape-like clusters on the conidiophores.  The microconidia (~2µm to 4µm) are spherical to pyriform in shape.  Macroconidia (20-50µm to 6-8µm) are cigar to club shaped and may show exhibit some distortion.  Macroconidia have a smooth exterior and are thin walled, usually have between 3 to 8 cells dividing the interior.  Macroconidia may be found more readily in younger cultures.  Production of both micro & macro conidia may vary with the isolate.  Coiled or spiral hyphae may be present and in some strains, structures described as nodular bodies or chlamydospores may be present.

Note: All photos which follow were taken with the DMD-108 digital microscope. 

T.mentagrophytes showing sessile microconidia along septate hyphae.

Note 100µm bar in upper right of this and several other photos. 

(400x, LPCB)

Trichophyton mentagrophytes - branched conidiophores bearing spherical conidia in clusters seen extending from septate hyphae.  (400x, LPCB)

T.mentagrophytes - another view as above.  A macroconidium can be seen near the lower center of the photo (400x, LPCB)

T.metagrophytes - a closer look at the branched condiophores bearing clusters of spherical microconidia.  Septations are visible in the hyphae and conidiophores.

(1000x, LPCB)

T.mentagrophytes -another look as in the previous photo.

(1000x, LPCB)

T.mentagrophytes - A 7-celled macroconidium.  Macroconidia are typically described as being cigar shaped or club shaped.

(400x, LPCB)

T.mentagrophytes - another 7-celled macroconidium with dimensions (inset)

(400+10x, LPCB)

T.mentagrophytes -an macroconidium which shows slight distortion (sides are not straight). Numerous spherical microconidia in lower right.

(1000x, LPCB)

T.mentagrophytes - a solitary cigar shaped macroconidium showing seven internal cells.  Walls are rather thin and the exterior is smooth.

(1000+10x, LPCB)

T.mentagrophytes - just by chance all this, and the previous macroconida all contain seven cells.  I found that young cultures (~3 days) produced the most macroconidia which seemed to diminish with additional incubation.  That said, the macroconidium pictured here is from a 6 day old slide culture.  It should always be kept in mind that structures may appear, disappear, develop or change with length of incubation.  It may be advisable to make several side cultures and harvest them at different time periods to observe development of structures.

(1000+10x, LPCB)

T.mentagrophytes - a couple of macroconidia are seen in this photo as well as clusters of microconidia.  A spiral hyphal element is seen in the upper center of the photo.

 (400+10x, LPCB)

T.mentagrophytes - a spiral hyphae is seen seen in the center left of this photo as it overlaps a macroconidium.  Microconidia throughout the photo.

(1000x, LPCB)

 T.mentagrophytes - more examples of spiral hyphae typical to T.mentagrophytes seen in this photo.

(400+10x, LPCB, 8 days incubation)

T.mentagrophytes - one last photo showing what is described as a nodular body or chlamydospore.  Clusters of microconidia seen in center-left.

(1000+10x, LPCB, 10 days incubation)

Physiological Tests:  a number of classical tests can be employed to speciate Trichophyton species.

·         Urease test: Positive

·         BCP-Milk Solids Glucose: Alkaline reaction

·         Hair perforation test: Positive

·         Growth at 37^oC: Excellent

·         Growth factor requirement*: None

*a variety of Trichophyton tubed agars are commercially available containing specific growth supplements (eg.inositol, thiamine, nicotinic acid, histidine).  The pattern or degree of growth in each can assist the speciation of Trichophyton.

Pathogenicity:  The anthropophilic strains are usually associated with chronic infections of glabrous skin, scalp, beard, nails and feet.

It is currently recommended* that Trichophyton mentagrophytes be reported as ‘Trichophyton mentagrophytes complex’ which also includes the former Trichophyton krajdenii.

*Best Practice by QMP-LS, external quality assessment agency.

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