myco 2

• Mycosis


  Any fungal disease
• Chronic


  Fungi grow slowly
• Classification of mycoses based on pathological site


  • Superficial
  • Cutaneous
  • Subcutaneous
  • Systemic (deep)
  • Opportunistic
• Sources of fungal infection


  • Animal
  • Environment
• Animal sources


  • Domestic animals are an important source of dermatophytes
  • Pigeons and other bird droppings carry Cryptococcus neoformans
  • Droppings at habitat of starling, chickens and bats carry Histoplasma capsulatum
  • Dog bite - Blastomyces
  • Bamboo rat in Thailand - Penicillium marneffei has been isolated
• Environmental sources


  • Majority of pathogenic fungi are found in soil and associated vegetation
  • All opportunistic fungi are present in the rural, domestic and hospital environment in the dust and the air
  • Histoplasma capsulatum in Missouri-Mississippi river valley
  • Coccidioides immitis in Arizona, New Mexico
  • Blastomyces dermatitidis in Ohio river valley
  • Cryptococcus neoformans in Eucalyptus tree
• Routes of fungal transmission

  • Airborne - inhalation of fungal spores
  • Contact transmission - dissemination of spores/yeast through skin-skin/skin-contaminated surface
  • Implantation/penetration through skin - (traumatic) implantation of fungal elements through skin
  • Vehicle-borne transmission
• Airborne transmission


  • Important for filamentous fungi such as Aspergillus spp.
  • Most common route of transmission in the immunocompromised patients
• Contact transmission


  • Dermatophytosis
  • Outbreak of C. albicans carried on the hands of healthcare worker
• Implantation/penetration through skin


  • Most important route of transmission for subcutaneous mycoses such as mycetoma, sporotrichosis, phaeohyphomycosis and chromomycosis
  • Mycotic keratitis
  • Use of intravenous devices
• Vehicle-borne transmission


  • Transmission of Candida and M. furfur through parenteral feed
  • Contaminated injectable anaesthetic agents
• Superficial mycoses


  • Confined to the non-living layer (top keratin-containing layer of the skin, the stratum corneum) of the skin and extra-follicular part of the hair
  • Elicit no inflammation
  • Immune system doesn't respond to the presence of the fungus
  • No lesion, no pain, no itchiness or non debilitating
• Types of superficial mycoses

  • Malassezioses
  • Tinea nigra
  • Black piedra
  • White piedra
• Malassezioses


  • Pityriasis (tinea) versicolor - presents as hypo to hyperpigmented macule or patches with slight scales on upper trunk, neck and upper arms
  • Malassezia folliculitis - pruritic, follicular papules, and pustules on the upper back, chest, shoulders, and less commonly face and neck
  • Seborrheic dermatitis - cradle cap on infant scalp
• Malassezia


  Lipophilic yeasts, including M. furfur-complex and M. pachydermatis

  skin scarpings examined with KOH-calcofluor white

  spaghetti and meatball appearance
• Tinea Nigra


  • Causative agent: Hortaea (Exophiala) werneckii
  • Asymptomatic, non-scaly, coin-sized, brown to gray patches on the palms and soles of young adults
  • diagnosis: presence of pigmented hyphae on KOH
• Black Piedra


  Superficial infection of hair shafts by Piedraia hortae results in asymptomatic, stone-like concretions on scalp and facial hair
• White Piedra

  • Causative agent: Trichosporon species including T.ovoides
  • Discrete-to-coalesced nodules that typically are white, cream, or brown, found on facial, axillary, and pubic hair
  • infection of perianal hair in HIV patients
  • diagnosis: hyaline arthroconidia, 2-4 septate hyphae, and differentiated blastoconidia from loosely packed hyphae
• Treatment of superficial mycoses

  1. Tinea Nigra: Topical therapy with azoles, naftifine, terbinafine, or Whitfield's ointment

  2. Piedra: 2% ketoconazole shampoo, shaving or clipping off infected hairs
• Cutaneous mycoses


  • Fungal infections of the skin, hair, and nails
  • Affect deeper epidermal layer, producing more tissue destruction and symptoms
  • Fungus may secrete keratinase (enzyme that degrades keratin)
  • Infection is transmitted by direct contact or contact with infected hair or cells
  • Primary cutaneous mycoses are caused by dermatophytes (dermatophytoses) and non-dermatophytes such as Candida spp. (dermatomycoses)
• Examples of cutaneous mycoses


  • Ringworm (Tinea capitis and T. corporis)
  • Athlete's foot (Tinea pedis)
  • Jock itch (Tinea cruris)
• Dermatophytes


  • Classified according to the source of infection: Arthropophilic (acquired from other humans), Geophilic (acquired from soil), Zoophilic (acquired from animals)
• Diagnosis of cutaneous mycoses


  1. Collect hair, skin, or nail scrapings for direct microscopic examination and culture

  2. Microscopy: material placed on slide, 20% KOH added

  3. Culture: necessary adjunct to microscopic examination, important for therapy and epidemiology
• Microsporum


  • Macroconidia has rough (echinulate) surface, prominent in M.canis
  • Microsporum species sporulate profusely, producing numerous macroconidia and lesser numbers of clavate microconidia
• Microsporum canis


  • Colonial characteristic: granular appearance, buff in color and a yellow–orange to orange–brown on the reverse side
  • Produces abundant fusiform, echinulate, thick-walled multiseptate macroconidia and few microconidia
• Microsporum gypseum


  • Colonies: flat, spreading, suede-like to granular, with a deep cream to tawny-buff to pale cinnamon-coloured surface
  • Culture surface: central white downy umbo (dome) or a fluffy white tuft of mycelium and some also have a narrow white peripheral border.
  • Culture reverse: A yellow brown pigment, often with a central darker brown spot
  • Macroconidia: symmetrical, ellipsoidal, thin-walled, verrucose, four- to six-celled with slightly rounded distal ends and truncate proximal ends
  • Numerous clavate-shaped microconidia are also present
• Epidermophyton


  • Single pathogenic species: E.floccosum
  • Characterized by the formation of obovate to broadly clavate multicell (1–9 septa) macroconidia with smooth walls and by the absence of microconidia
• Epidermophyton floccosum colonies


  • Develop slowly, frequently grainy, develop folds, suede-like in texture, color range from olive to yellow or yellow–brown
• Trichophyton


  Macroconidia: multicell (1–12 septa), smooth walled, variable in shape (clavate, cylindrical, cylindrofusiform), formed singularly or in clusters on conidiophores
• Trichophyton rubrum


  • Colonies: white to buff in color, with or without a wine red color on the reverse side
  • Presence of club-shaped microconidia arranged along the hyphae (en thyrse)
  • Smooth-walled macroconidia
  • Inability to perforate hair in vitro
  • Lack of urease production

  
• Trichophyton mentagrophytes complex


  • Zoophilic strains: granular, off-white colonies
  • Anthropophilic strains: white and fluffy colonies
  • Production of rounded microconidia arranged along the hyphae and in grape like clusters (en grappe)
  • Smooth-walled macroconidia
  • Spiral hyphae
  • Positive test for in vitro hair perforation
  • Production of urease
• T. tonsurans


  • Colonies appear powdery or grainy, usually with a brown to tan color that may be lost upon subculture
  • The reverse pigment if present has a yellow–brown or red appearance
  • The main identifying characteristics include the production of abundant microconidia of varying shapes, club, or elongated or balloon-like
  • Some strains make abundant arthroconidia and chlamydospores
  • Growth is stimulated in the presence of thiamin
• T. violaceum


  • Growth is slow, producing colonies that are heaped and convoluted, with a violet or lavender surface and a purple color on the reverse side
  • The main identifying characteristics are the rate of growth,colony appearance, lack of micro- and macroconidia,and stimulation of growth by thiamin
• T. schoenleineii


  • Growth is slow, producing white to tan, heaped, and convoluted colonies without any color on the reverse side
  • Main identifying characteristics include lack of both micro- and macroconidia, and theformation of "favic chandeliers," which are antler-like structures at the tips of hyphae
• T. concentricum


  • Growth is slow, producing beige to brown or reddish colonies that are convoluted, becoming glabrous
  • Main identifying characteristics are the lack of sporulation, stimulation by thiamin (50%of strains), the geographic location, and the clinical picture
• Dermatophytes are primary cutaneous pathogens and comprise the largest group of fungi that cause skin disease
• Fungi appear to be uniquely qualified to invade hair, nails, and skin, in part due to their ability to produce keratinases, which are enzymes that digest keratin in vitro
• Another factor that may enhance their pathogenicity is the production of mannan components that are immunoinhibitory in vitro
• Tinea Unguium (Onychomycosis)


  Infection of fingernails or toenails by dermatophyte fungi
• Onychomycosis


  A broader term that also encompasses nail infections by nondermatophyte moulds, yeasts, and occasionally bacteria