Lecture 4 - Subcutaneous Mycoses

muscle, lymphatic vessels, and connective/neighboring (contiguous) tissue

NO! they do not disseminate in blood

Progressive, non-healing ulcers
Presence of draining sinus tracts

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Chronic skin/soft tissue infection

Mass (where inoculation happens), sinus formation, and discahrge with grains (white and black)

Results in disability and deformity.

Antifungals, but often unable to eradicate fungus; need to be given for long periods (sometimes years) and are expensive.
Amputation and recurrences are common

Foot (sometimes hand - second common), but can affect any area of body.

Thorn prick, other lesions of the skin (mild trauma) and exposure to contaminated environemtn

Considered a tropical disease and poor countries are affected. Especially children in remote, rural areas; farm workers/herdsman direct contact with soil

3:1 male to female

mycetoma caused by a fungi

mycetoma caused by bacteria

Madurella

M. mycetomatis
M. grisea

Pseudallescheria boydii - white grain
Leptosphaeria spp.

Nocardia
Streptomyces
Actinomyces

Mycetoma

1. Presents as a slowly progressive, painless subcutaneous swelling
2. multiple secondary nodules evolve that may drain through multiple sinus tracts
3. The sinuses often discharge grains or granules containing colonies of the causative organism

Grains are colorless

Grains are black

soil, polluted and stagnant water and manure - via inhallation/ near drowing or traumatic inoculation (ex: thorn)

a condition afflicting the immunocompromised (opportunist); associated with cystic fibrosis patients.

Lung, CNS, systemic spread (sinusitis, arthritis, meningitis, brain abscess, lung abscess, lung fungus ball)

very difficult; resistant to Amphotericin B and many antifungal drugs

cleistothecium: multicellular, sexual fruiting body, with asci and ascospores inside.

Rarely seen with clinical specimens; requires 2-3 weeks of incubation.

Found in the soil

Black grains with pale centers
Common cause of mycetoma in West Africa

Hyphae, ascomata (cleistothecia), asci, and ascospores [sexual]

both! May be aerobic or anaerobic

soil and water

Normal inhabitants of GI tract humans/animals (from oropharynx -> lower bowel)

GPR, filamentous that tend to branch and may fragment in coccbacilliary or coccoid forms (irregular staining)

colony appearance varies: waxy, dry, chalky, bumpy, crumbly, adherent; white, tan, orange, yellow, pink, red

Yellow-orange granule of intertwined Actinomyces filaments solidified with elements of tissue exudate

when is transgressed the epithelial barrier under sufficiently low oxygen tension.

Known bacteria that can cause mycetoma and lung infections (in immunocompromised patients)

Streptomyces spp.

rose gardener's disease caused by DIMORPHIC FUNGUS

along dermal and subcutaneous lymphatics <- majority of cases

Fungal infection

colorless (hyaline), nonpigmented, or lightly color mold with septate hyphae in tissue

Fungi that produces a dark pigment

infections caused by darkly pigmented fungi.

Phaeohyphomycosis has NO SCLEROTIC BODIES!!

Also known as Mucormycosis; can be an opprotunistic infection caused by a group of fungi, mucormycetes