Subcutaneous Mycoses_prt.2 Flashcards
(50 cards)
- Madura Foot or Maduromycosis, mycetoma caused by a fungus.
➢Eumycetoma
– mycetoma caused by an actinomycete;
more invasive and spreading to the underlying tissue
➢Actinomycetoma
➢Chronic subcutaneous infection induced by traumatic
inoculation with any of several saprophytic species of fungi or
actinomycetous bacteria that normally found in soil.
➢Clinical features: local swelling, interconnecting, often draining, sinuses or fistulae that contain GRANULES, which are microcolonies of the agent embedded in tissue material.
EUMYCETOMA
Eumycetoma
• Etiological Agents: a wide range of fungi…
Most common:
Madurella mycetomatis
M. grisea
Scedosporium boydii
Scedosporium apiospermum,etc.
• MOT: Snake bites, knives, splinters, thorns, and insect bites
• WHO-recognized neglected tropical disease with significant disease burden, 2016
Eumycetoma
• Distribution: Barefoot walking populations of tropical/subtropical countries – India, West Africa (Senegal, Sierre Leone). Where countries are endemic – part
of the “Trans-African Belt” or “mycetoma belt.”
Rare in developed nations.
Eumycetoma
– the hallmark of mycetoma
➢GRAINS
➢ Sinuses discharge serosanguinous fluid containing granules, which vary in size, color, and degree of hardness, depending on species.
Eumycetoma
➢ **Start out as a small hard painless nodule, ** overtime begins to soften, and ulcerate to discharge a viscous, purulent fluid containing grains.
Infection slowly spreads to adjacent tissue, including bone, causing considerable deformity.
Eumycetoma
Eumycetoma
Classified based on the type of grain produced:
• Dark and black grains:
Madurella mycetomatis
Exophiala jeanselmei
Eumycetoma
Classified based on the type of grain produced:
White and pale unstained grains:
Acremonium spp.
Scedosporium apiospermum
Scedosporium boydii
Eumycetoma
Classified based on the type of grain produced:
Yellow-brown:
Nocardia brasiliensis
Nocardia otitidiscaviarum
Actinomadura madurae
Streptomyces somaliensis
Eumycetoma
Classified based on the type of grain produced:
• Yellow:
Pleurostomophora ochracea
showing numerous draining sinuses.
There is destruction of bone, distortion of the foot, and hyperplasia at the openings of the sinus tracts.
draining sinus (cut open in this preparation) containing black grains
Mycetoma
Granules are composed of
septate fungal hyphae, 2-6 um
or greater, dematiaceous (black grain) or hyaline (pale or white grain)
Eumycetoma
➢ **Start out as a small hard painless nodule, ** overtime begins to soften, and ulcerate to discharge a viscous, purulent fluid containing grains.
Infection slowly spreads to adjacent tissue, including bone, causing considerable deformity.
Eumycetoma
• Culture shows the typical brown diffusible pigment (pyomelanin) in the agar.
• Colonies are slow growing, flat and **leathery at first, white to yellow to Browmish, ** folded and heaped with age and the formation of aerial mycelia.
Madurella mycetomatis
• A brown diffusible pigment is characteristurly______
can be distinguished from Madurella grisea by growth at 37°C and its inability to assimilate sucrose.
Mucetomatis
showing phialides (rarely seen as most isolates are sterile);
• Two types of conidiation have been observed:
• First - being flask-shaped phialides that bear rounded conidia
• Second - being simple or branched conidiophores bearing conidia (3- 5um) with truncated bases.
• The optimum temperature for growth of this mold is 37°C.
M. mycetomatis
MYCETOMA
Colonies are **fast growing, ** greyish-white, suede-like to downy with a greyish-black reverse.
Scedosporium (Pseudallescheria) boydii
• Cleistothecia - non-ostiolate
• Ascocarps - yellow to brown to black, spherical, 50-200 um in diameter, submerged in the agar, composed of irregularly interwoven brown hyphae.
• Crushed cleistothecia release numerous, faintly brown, ellipsoidal ascospores,
4-5 x 7-9 um in size.
Scedosporium (Pseudallescheria) boydii
Crushed cleistothecium of ______mounted in Melzer’s reagent, showing dextrinoid reaction of
ascospore
P. boydii
• Fascicles (bundles) of conidiophores bound together in synnemata (wheat sheaf appearance)
Scedosporium apiospermum/S. boydii
The conidial states of S. boydii and
S. apiospermum are morphologically indistinguishable. But:
•_______ - **homothallic, ** smaller cleistothecia (50-200um)
•________- heterothallic (requires mating of two strains), larger cleistothecia (140-480um)
S. boydii
S. apiospermum
