PBL 2 - Possible fungal pathogens by PEI SHAN

Common fungal pathogens that the soldiers may encounter in the indonesia jungle are as listed below:

1. Dermatophytes
 Epidermophyton floccosum
 Microsporum sp.
o Microsporum canis
o Microsporum ferrugineum
o Microsporum fulvum
 Trichophyton sp.
o Trichophyton ajelloi
o Trichophyton concentricum
o Trichophyton mentagrophytes var. interdigitale
o Trichophyton mentagrophytes var. mentagrophytes
o Trichophyton rubrum
o Trichophyton rubrum downy strain
o Trichophyton rubrum granular strain
o Trichophyton tonsurans
o Trichophyton verrucosum

2. Yeasts
 Candida
o Candida albicans
o Candida famata
o Candida glabrata
o Candida guilliermondii
o Candida krusei
o Candida lusitaniae
o Candida parapsilosis
o Candida tropicalis
 Cryptococcus
o Cryptococcus gattii
 Malassezia furfur

3. Dimorphic Pathogens
 Blastomyces dermatitidis
 Histoplasma capsulatum

4. Hyphomycetes
(hyaline moulds)
 Aspergillus sp.
o Aspergillus flavus
o Aspergillus fumigatus
o Aspergillus nidulans
o Aspergillus terreus

5. Hyphomycetes
(dematiaceous moulds)
 Sporothrix schenckii


Transmission/ Pathogenesis
1. Dermatophytes
 Can be anthropophilic, zoophilic or geophilic depending on the source (human, animal, soil)
 Spread by contact with arthrospores (thick-walled vegetative cells formed by dermatophyte hyphae) which can survive for months
 Shed from primary host in skin scales and hair
 Invade keratinized structures of the body

2. Yeasts
Candida
 Part of normal skin flora
 Colonizes damaged skin, intertriginous (apposed skin sites which are often moist and chafed), and oral sites - when there is substantial lowering of host resistance

Cryptococcus
Cryptococcosis may involve the skin, lungs, prostate gland, urinary tract, eyes, myocardium, bones, and joints
- var. neoformans
 often found in soil which has been contaminated by bird excrement
 inhalation of airborne cells
 causes lung infection or even CNS involvement
- var. gattii
 Eucalyptus tree and decaying wood forming hollows in living trees

Malassezia furfur
 Common skin inhabitant
 Pathogenicity occurs when yeast change to hyphae form; stimuli unknown

3. Dimorphic Pathogens
Blastomyces dermatitidis
 Inhalation of airborne spores
 Can become widely disseminated in body
 Fungal infection in lungs; may be confused with tuberculosis
 Can produce abscesses

Histoplasma capsulatum
 Grown as hyphae in soil where there are bird’s droppings
 Inhalation of airborne spores, grows as yeast cells
 Survive intracellularly after phagocytosis
 Can produce acute and chronic pulmonary disease

4. Hyphomycetes (hyaline moulds)
Aspergillus sp.
 Inhalation of airborne stages (conidia)
 Causes thrombosis and infarction when blood vessels invaded
 Patial blockage of airways from fungal mass
 Opportunistic infectant

5. Hyphomycetes (dematiaceous moulds)
 Saprophytic fungus, dimorphic
 Infect through trauma; wounds in skin
 cats are the most notable source of transmission of sporotrichosis to humans
 Ulceration or abscess formation in draining lyphatics


Clinical features
1. Dermatophytes
 May cause one or more of the followings: tinea (“ringworm” of) capitis (hair and skin of scalp), tinea corporis (body), tinea cruris (crotch), tinea manuum (hands), tinea unguium (nails), and tinea pedis (feet)
 Lesion; scaling patch with a raised margin
 Itching
 Often dry and scaly
 Sometimes cracks, hair loss
 Inflammation

2. Yeasts
Candida
 May cause nail pathology in some, especially in patients with mucocutaneous candidiasis.
Cryptococcus
 Influenza-like syndrome or pneumonia
 May involve meningitis (if CNS infected)
Malassezia furfur
 Confined to trunks/proximal parts of limbs
 Associated with hypo- hyper-pigmented macules that coalesce to form scaling plaques
 Lesions not itchy

3. Dimorphic Pathogens
Blastomyces dermatitidis
 A flulike illness with fever, chills, myalgia, headache, and a nonproductive cough may occur, which resolves within days
 Depending on the area of involvement, it may include the following signs, although sometimes asymptomatic: Skin lesions, bone or joint pain, pain on urinating and hoarseness
Histoplasma capsulatum
 Symptoms of acute respiratory histoplasmosis, including fever and cough, occur within two weeks of exposure
4. Hyphomycetes (hyaline moulds)
Aspergillus sp.
 Allergic bronochopulmonary reactions

5. Hyphomycetes (dematiaceous moulds)
 Development of a papule that enlarges to a nodule and usually ulcerates over a period of 1 to 2 weeks.
 may progress to the lymphatic system and cause the lymphocutaneous form of sporotrichosis if untreated

General Precautions to prevent fungal infections
(though airborne microbes are hard to prevent)

• clean, disinfect and dress up wounds thoroughly - prevent microbes from entering through wounds
• personal hygiene: proper wash-up after training to remove the debris of soil that may have stick onto the skin
• report to military heads if sick: immunosuppressed individuals are more proned to opportunistic infections

References

1. Book: Medical Microbiology third eition by M., Cedric at. el.
2. Dermatophytes: http://www.cfsph.iastate.edu > Factsheets > pdfs > dermatophytosis.pdf
3. Mycology: http://www.mycology.adelaide.edu.au
4. Blastomyces dermatitidis: http://www.emedicine.com > med > topic231.htm
5. Malassezia furfur: http://www.anaisdedermatologia.org.br > artigo_imprimir_en.php?artigo_id=10192
6. Histoplasma capsulatum: http://wonder.cdc.gov > wonder > prevguid > p0000406 > p0000406.asp
   

Reported by Pei Shan, TG02