Saturday 21 April 2012

Microsporum audouinii

Microsporum audouinii  (fungus - dermatophyte)

Ecology:  Microsporum audouinii is a cosmopolitan anthropophilic dermatophyte which is spread person to person.  Now rarely seen in North America or Europe however it remains the most common cause of human ringworm, primarily tinea capitis (scalp infection) on the African continent.  Travelers and migrant workers may bring this infection from endemic areas.  M.audouinii infection is more prevalent in prepubescent children.  Hairs will fluoresce under a ultra-violet Wood’s Lamp.

Macroscopic Morphology:  On Sabouraud-Dextrose agar the colonies grew with a moderately rapid pace.  Colonies were rather flat and spreading with a radiating margin.  They appeared to have a greyish-white to tan to beige colouration with the reverse a salmon colour to rose-brown.

 M.audouinii on SAB at 3 weeks*  (reverse shown below right)
*Correction:  This appeared to be very luxuriant growth for a Microsporum to have developed in only 10 days as I had originally stated.  On reviewing my original files I see that this culture was incubated on SAB/SDA at 30ᵒC.  (mea culpa)

May 2nd, 2016:  I've added another photograph from my files of M.audounii on Sabouraud Dextrose Agar (SAB or SDA, if you prefer) incubated at 30ᵒC for 14 days.  As you can see, the growth is much more sparse that that above.  I'm not sure what my thought process was some four years ago when I originally posted the culture photo.

 M.audounii on SAB (SDA) incubated at 30ᵒC for 14 days (Nikon)
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Microscopic Morphology:  Hyphae are septate and often show pectinate (comb-like) and racquet cells (See photo).  Both intercalary (in the middle of a hyphae) and terminal (at the end of a hyphae) chlamydospores may be present.  Terminal chlamydospores may have a small point or peak at their apical end.  Sources report that microconidia and macroconidia are rare.  Microconidia are ovoidal to clavate (club shaped).  Macroconidia can be elongated or spindle shaped and may be irregular or distorted in their shape.  They may also show a slight constriction along their length often closer to the center.  The macroconidia are thick-walled, variable in size (30-80 µm X 8-14 µm) and number of internal cells.  They are usually echinulate (small spiny like projections on surface) to some degree.

Photos below were taken with the Nikon Coolpix camera or the Leica DMD-108 Digital Microscope as indicated.  Read more about the photography in the post entitled 'Toys'.

 M.audouinii hyphae bearing microconidia (LPCB X 400 -Nikon)
(authoratative sources state that microconidia are rare however the isolate I'm presenting here seems to be capable of producing ample numbers.)

M.audouinii - photo just to show the septate hyphae (S) and microconidia (M)
 (LPCB X1000 DMD-108)

 M.audouinii - starting the formation of racquet hyphae which appear somewhat like a tennis racquet, narrower on one end and wider-round on the opposite end usually stacked in greater numbers than in my photo.  (LPCB X1000 DMD-108)

 M.audouinii - what appears to be racquet hyphae though not "text-book" in shape.
(LPCB X1000)

As above

M.audouinii -Pectinate hyphae (comb-like structure of hyphae)
(LPCB X1000)
M.audouinii -Pectinate hyphae (comb-like structure of hyphae)
(LPCB X1000)

M.audouinii - another example of pectinate hyphae (LPCB X1000 DMD-108)

M.audouinii - jumble of structures showing pectinate hyphae and one intercalary chlamydospore
(LPCB X1000 DMD-108)

M.audouinii - Terminal chlamydospore (T) shown, often exhibits a little apical point or peak.  Also an intercalary chlamydospore  (IC) (in the middle of a hyphae or perhaps a hyphae running through it)  (LPCB X1000)

M.audouinii - A better view of an intercalary chlamydospore showing it in between the run of a hyphal element. (LPCB X1000+10X digital zoom DMD-108)

M.audouinii - 2 young macroconidia (and lots of microconidia!!)
(LPCB X1000 Nikon)

M.audouinii - Macroconidia forming with constriction near middle.  Internal cells not visible.
(LPCB X1000 Nikon)

M.audouinii - 2 macroconida, long thin on left and more typical spindle shaped on right
(LPCB X1000 DMD-108)

M.audouinii - macroconidia with slight narrowing near middle
(LPCB X1000 Nikon)

M.audouinii - macroconidia with more drastic narrowing near middle than the photo above.  Internal cellular structure visible.  (LPCB X1000 Nikon)

M.audouinii -macroconidia somewhat distorted with echinulate surface texture. (rough, small projections) Internal cells clearly visible (LPCB X1000 Nikon)

M.audouinii - macroconidia with four internal cells (LPCB X1000 Nikon)

M.audouinii - Distorted 2 celled Macroconidia (LPCB X1000 Nikon)

M.audouinii - fairly young macroconidia forming (LPCB X 1000+10X digital zoom DMD-108)

M.audouinii - Short 2 celled macroconidia (LPCB X1000+10 digital zoome DMD-108)

M.audouinii - okay, last one - Macroconidia with rounder apical end than M.canis
(LPCB X1000 DMD-108)

Physiological Tests:  Hair perforation test is negative.  M.audouinii has no specific growth factor requirements.  Alkalinization occurs in BCP-milk solids glucose (BCPCG) media.  It shows weak to little growth on autoclaved rice grains with possible production of a brownish pigment.

Thursday 12 April 2012

Paecilomyces variotii

Paecilomyces variotii (Fungus)
Ecology: Ubiquitous – worldwide distribution found in soil and decaying vegetation. May be isolated as an environmental or laboratory contaminant.
Macroscopic Morphology: Moderately rapid growth on SAB reaching about 7 to 8 mm after a week. Colonies are tan to yellowish-brown (mustard) in colour, darkening slightly as they mature. Texture is powdery to floccose. Reverse may appear darker.

P.variotii on SAB at 1 week showing a yellowish-brown colour. Several failed attempts were made to produce an isolated colony growing centered on the plate. The conidia are so loosely bound that even the closing of the incubator door dispersed maturing conidia to further seed the media.

Microscopic Morphology: Produces hyaline, septate hyphae.
Conidiophores bear supporting cells which branch verticillately, each producing some 2 to 7 phialides about 3.5 µm to 6.5 µm in width and 150 µm in length. Phialides are cylindrical or ellipsoidal in shape which widen from the base then taper to a thin neck somewhat resembling a bowling pin. Conidia are subspherical or ellipsoidal in shape, smooth walled and about 2-4 µm by 3-5 µm in size. Conidia generally arise in long divergent chains. Thick-walled intercalary or terminal subglobose chamydospores (4-8 µm) may be produced.
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All photos that follow were taken with the Leica DMD-108 Digital Microscope. Differences in structural size at same magnification may be due to cropping of photos.

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P.variotii (LPCB X250)
P.variotii (LPCB X400)
P.variotii (LPCB X400)
P.variotii (LPCB X1000)
P.variotii (LPCB X1000)
(A few more pretty pictures just to get a better feel of what this organisms looks like)
P.variotii (LPCB X1000)
P.variotii (LPCB X1000)
P.variotii (LPCB X1000 + 10X digital zoom)
Note the cylindrical 'bowling pin' shaped phailides - more thin and delicate than those of Penicillium species.
P.variotti showing phailides and disrupted conida. Conidia generally are produced in longer chains however they are so loosely bound that the are easily disrupted even in spite of my use of a slide culture and working very delicately. (LPCB X1000)
P.variotii showing phialides bearing conidia at left and chamydospores on right (LPCB X1000)
Okay, just a couple more photos...
P.variotii (LPCB X1000 + X10 digital zoom)
Subspherical to elipsoid conidia scrambled above phailides attached to supporting cells on conidiophore extending from septate hyaphae.
Paecilomyces variotii (LPCB X1000)
(Intended as 1024 X 768 wallpaper)
Physiology: Paecilomyces variotii is thermophillic and can grow well up to 50oC and possibly higher.
Pathology: Another opportunistic fungus which has been rarely implicated in human disease, however may pose increase risk to immunocompromised individuals. Has been implicated in prosthetic valve endocarditis, osteomyelitis, endophthalmitis, otitis media, pneumonia and cellulitis.
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Monday 9 April 2012

Neosartorya pseudofischeri

Neosartorya pseudofischeri (Anamorph – Aspergillus thermomutans) [Fungus]

Note: This fungus arrived at our lab as a one of several isolates for proficiency testing.

(When the sexual Teleomorph stage is present, its name takes precedence over the asexual Anamorph stage)

Ecology: Neosartorya pseudofischeri is widely distributed in nature and is found in soil, seeds, and anthropogenic habits, particularly cellulosic materials such as paper products. The species is thermotollerant, able to grow well up to 45oC, with growth limited at about 47-48oC. The species may be inhibited by cycloheximide containing media.

Pathogenicity: In spite of its wide distribution it remains a rather uncommon opportunistic human pathogen. It is being isolated in greater frequency from immunocompromised patients. Neosartorya pseudofischeri has been implicated in endocarditis, osteomyelitis, peritonitis, keratitis, and has been reportedly isolated from blood cultures.

Macroscopic Morphology: On Sabouraud Dextrose agar Neosartorya pseudofischeri grows fairly rapidly, producing a white to off-white woolly to cottony colony. The reverse is a rather non-descript pale colour. Conidial production may be scant producing a weak smoky grey-green colour on repeated subculture and prolonged incubation.

Neosartorya pseudofischeri on SAB agar after 72 hours at 30oC (Note white colour) -Nikon

Anamorph Aspergillus thermomutans form appearing after several subcultures and prolonged incubation. Pale smoky-grey green appeared in the center of the colony but developed as it appears in the photo above. The greenish colour and appearance of the fruiting structures (conidiphores) may lead to confusion with Aspergillus fumigatus. If the sexual (teleomorph) stage is present, its name (Neosartorya pseudofischeri) takes precedence over the anamorph (Aspergillus thermomutans)

Microscopic Morphology: Teleomorph – Neosartorya pseudofischeri produces cleistothecia (Ascomata) singly or in small clumps often of varying size. They appear as cream to pink coloured, soft-walled globose structures anywhere from 120 µm to 300 µm in diameter after about a week but can reach sizes even larger. They contain spherical to sub-spherical 8-spored asci (8-19 µm to 10-12 µm) which normally break down within the cleistothecia (dehiscence), releasing the ascospores. Ascospores are lenticular (lens) in shape with two prominent equatorial crests (5-8 µm to 4-6 µm) in diameter. They appear uncoloured and rough in texture due to triangular-like projections on their surface.

Anamorph- Hyphae are septate and hyaline. Conidiophores are smooth-walled and hyaline to a pale yellowish colour, 200 µm to 300 µm in length. Initially, the conidia can be found radiating from the conidiophore vesicle but they may appear somewhat columnar with longer incubation. Vesicles are sub-spherical in shape, about 10-17 µm in width, uniseriate and bear hyaline smoky-grey to pale green phialides. From the phialides extend sub-spherical, smooth-walled conidia about 3 to 4 µm in diameter which also appear a pale greyish-green.

All microphotographs in this posting were taken with the Leica DMD-108 Microscope

(Click on any photograph to enlarge for better viewing)

Neosartorya pseudofischeri hyphae and conidiophores on slide culture (LPCB X100)

Neosartorya pseudofischeri conidiophore attached to hyphae with what appears to be foot cell.

Neosartorya pseudofischeri conidiophore bearing uniserate phialides and radiating conidia.

Neosartorya pseudofischeri conidiophore and hyphae (LPCB X400)


Neosartorya pseudofischeri conidiophore (LPCB X1000)

Neosartorya pseudofischeri conidiophore on left and spiral hyphae on right. (LPCB X1000)

This isolate had a great number of spiral hyphae, a structure not mentioned in any reference material consulted.

Neosartorya pseudofischeri -curious number of spiral hyphae present in our isolate (LPCB X1000)

Neosartorya pseudofischeri conidophore with terminal vesicle, uniserate with conidia (LPCB X1000)


Neosartorya pseudofischeri cleistothecia (ascomata) (LPCB X400)


Neosartorya pseudofischeri disrupted cleistothecia (ascomata). Ascospores escaping from split cleistothecia at top of photo (LPCB X100)

Neosartorya pseudofischeri cleistothecia spewing ascospores from top (LPCB X400)

Neosartorya pseudofischeri cleistothecia (ascomata) [1]. Structure is disrupted releasing Asci [2] which when intact contain eight individual Ascospores[3] now freed. (LPCB X400)

Neosartorya pseudofischeri cleistothecia (ascomata) split in the middle (LPCB X400)

Neosartorya pseudofischeri clump of cleistothecia (LPCB X100)

Neosartorya pseudofischeri disrupted cleistothecia or asomata (LPCB X400).

You can try disrupting the clestiothecia by moving the microscope objective out of the way and pressing down on the coverslip or tape preparation with the eraser end of a pencil. Swing the objective back into place and re-examine the structure. Repeat until you break something! Recall that with the cleistothecia produced by Aspergillus nidulans, you can add a drop of 10% KOH to the disrupted structure and a chemical reaction will turn the ascospores turning them purple. Such a Reaction does not occur with this clestiothecium/ascospores adding evidence that this fungus is not Aspergillus nidulans.

Neosartorya pseudofischeri Asci and Ascospores (LPCB X1000+10)

Neosartorya pseudofischeri Asci & Ascospores. Inset: note the rough surface and projections on the individual ascospores. The sub-round to lenticular (lens shaped) ascospore with arrows in the upper left corner shows the equatorial crests quite well. Looks like a little flying saucer!

(LPCB X400)

Okay, last one! Neosartorya pseudofischeri, again showing asci containing 8 ascospores, some of which have been released from dissolved asci. Freed ascospores have a rough surface with projections which under electron microscopy appear somewhat triangular. The equatorial crests are also visable on the ascospore turned sideways. (LPCB X1000+10)


Neosartorya pseudofischeri or its anamorph may possibly be under reported as a pathogen because it may be confused with Aspergillus fumigatus. This confusion may cause it to be improperly diagnosed or possibly dismissed as a contaminant. Aspergillus species rarely produce white colonies on initial culture and the smoky pale greenish-grey colour that may be produced on added incubation differs from the dark greenish blue of Aspergillus fumigatus. Antifungal susceptibility may differ significantly between Neosartorya pseudofischeri and Aspergillus fumigatus which may impact on patient recovery.

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