Module#2-Student Activity Sheet SUPERFICIAL YCOSES
Module#2-Student Activity Sheet SUPERFICIAL YCOSES
Module#2-Student Activity Sheet SUPERFICIAL YCOSES
Internet source:
Biron,Health Group(20211);Superficial Mycoses-Direct
Examination
https://www.biron.com/en/glossary/superficial-mycoses-
culture/
Dermatology Research and Practice Volume 2016
https://www.hindawi.com/journals/drp/2016/9509705/
A. LESSON PREVIEW/REVIEW
Superficial mycoses are fungal infections of the skin, hair, and nail that invade only the stratum corneum
and the superficial layers of the skin.
Introduction
Superficial(surface) mycoses are skin infections caused by fungi and yeasts. The majority of these fungi and
yeasts on the skin are normal. It is their excessive proliferation that can cause lesions, which are usually benign, but
which can affect quality of life (itching, odour, appearance, etc.)
Superficial mycoses are examined in two stages. The first involves a direct microscope examination to detect the
presence of mycelial elements (filaments that indicate the presence of fungi) and Yeasts (Candida). Regardless of the
results of the direct examination, the specimen is then cultured to confirm the presence or absence of potentially
pathogenic fungi and yeasts.
B.MAIN LESSON
SUPERFICIAL MYCOSES
- Limited or confined to the outermost layer of the skin, hair and nails
- Does not invade living tissue
- Causes
✔ Profuse sweating
✔ Poor hygiene
✔ Poor immunity
- Clinical picture:
✔ White corneal plaques with the development of satellite lesions and endothelial plaques
- Etiologic agent:
✔ Yeasts: Candida species
✔ Filamentous fungi: Fusarium, Aspergillus, Alternaria, Curvularia, Penicillium, Mucor
- Pathogenesis:
✔ Fungi gain entry into stroma through a defect in epithelial barrier.
✔ In stroma, cause tissue necrosis & host inflammatory reaction.
✔ Fungus can penetrate deep into stroma & through intact descemet’s membrane.
✔ Blood borne growth inhibiting factors may not reach avascular structures of eye cornea so fungi continues
to grow & persists (i.e. why conjunctival flap help in control of fungal infection)
- Risk Factors:
✔ Trauma (M/C)
✔ Contact lens use: Cosmetic lens – filamentous
Therapeutic lens – Yeasts
Overall bacterial infection more common with contact lens users
✔ Topical medications: Corticosteroids
Broad spectrum antibiotics
✔ Corneal Sx- penetrating keratoplasty, LASIK
✔ Chronic Keratitis – in cases of Herpes simplex, Herpes zoster, Vernal/Allergic keratitis
✔ Immunocompromised State – in cases of HIV, Leprosy
Laboratory Diagnosis:
- Symptoms of otomycosis includes: pain, itchiness, redness, hearing loss, discharge from ears, swelling,
physical narrowing of ear canal
Microscopic appearance: 10-290% KOH- hard and Microscopic appearance: white nodules lager and softer
black nodules resembling nits of lice
Open nodules containing oval asci with 8 ascospores Hyphae; tend to break into arthospores
4. Tinea nigra/ Keratomycosis nigricans palmaris/ Tinea nigra palmaris/Pytyriasis nigra/Microsporis nigra
- Clinical picture: Superficial infection on the palm of the hands or the sole of the foot
- Etiologic agent: Clasdosporium wernickii or Hortae or Exophiala or Phaeoannellomyces werneckii
- Outstanding Characteristics: 10-20% KOH: Strongly dematiaceous septate hyphae
5. Pityriasis versicolor
- Clinical picture: Patchy brown desquamating rash involving mainly the trunk, arms, shoulder and face “ blotchy
appearance
- Characteristic microscopic appearance: in 10-20% KOH
Clusters of short angular hyphae along with some yeast cells “spaghetti
and meatballs appearance”
4. Invades the keratinized areas of the body as skin, hair and nails
6. An antifungal in which the mechanism of action is to inhibit CYP P450 14 a-demethylase enzyme
C. LESSON WRAP-UP
Superficial mycosis is a disease of the skin and its appendages caused by fungi. It comprises dermatophytosis,
candidiasis, and pityriasis versicolor .They have the affinity to keratin rich tissues and produce dermal inflammatory
response, intense itching, and cosmetically poor appearance. Superficial mycoses are common worldwide. They are
thought to affect 20% to 25% of the world’s population, and the incidence of superficial mycoses continues to increase. An
etiological agent of superficial fungal infections consists of dermatophytes, yeasts, and nondermatophyte molds.
Dermatophyte is responsible for most superficial fungal infection and the expected lifetime risk of getting a dermatophyte
infection is between 10 and 20.
The dermatophytes are a group of closely related fungi infecting skin, hair, and nails in living host including man.
They produce an infection called dermatophytosis, also known as ringworm or tinea. The skin infections caused by
nondermatophytic fungi are known as dermatomycoses whereas hair and nail are known as piedra and onychomycosis,
respectively.