Non systemic Fungi :-
1) Malassezia furfur - It causes Ptyriasis or Tinea Versicolor.On KOH mount it appears as “
Yeast clusters and short septate hyphae.This is a superficial infection of keratinized tissues.Causes blotchy hyperpigmentation of skin.
On KOH scrapings its seen as sphagetti and meat ball appearance.
Treatment- Topical Selenium sulfide[selsun]
2)Dermatophytes - It causes Dermatophytic infections ie , Tineas(Ringworms).This is Cutaneous fungal infection.It has three genera -
a) Trichophyton
b) Microsporum
c) Epidermophyton
3) Sporothrix schenckii - It is a dimorphic fungi.It causes Sporotrichosis {Rose gardener disease} . It is “cigar shaped”yeast in the tissue.It causes subcutaneous or lymphocutaneous fungal infections.
Also causes pulmonary sporotrichosis.
Treatment- itraconazole / potassium iodide in milk.
4) Histoplasma - It is a dimorphic fungi and is present as tuberculate spores. Present in eastern great lakes, ohio,Mississippi and Missouri river beds. Forms powdery white colonies. It causes lung diseases called fungus flu and pneumonia. Macrophages are filled with histoplasma. It has no capsule. People who do cave exploring gets it as its present in bat feces. Treatment- Ketoconazole/ Amphotericin B.
5) Coccidiodes immites- It is a dimorphic fungi. Present in southwestern California especially in San Joaquin valley, Arizona,Texas,Nevada,New Mexico.It causes pneumonia and meningitis.Causes Desert valley fever.Pulmonary lesions calcify as they heal.Symptoms are Erythema Nodusm(Desert bumps).Sputum has spherules and endospores.It disseminates in the 3rd trimester of pregnancy.
6) Blastomyces Dermatitides- It is a dimorphic fungi.Sputum shows broad based budding and double contoured yeast cells. It is oval shaped.Present in upper great lakes,ohio,Mississippi river beds, Southeastern seaboard of USA and northeastern Minnesota into Canada.Causes acute and chronic pulmonary disease.Associated with rotting woods. Forms granulomatous nodules. It reproduces by budding. Treatment- Amphotericin B.
7) Aspergillus Fumigatus - It is a septate hyphae at 45 degrees.(V shaped branching). Causes Aspergillomas(fungus ball) it represents aspergillus colonization. They develop in old lung cavities(tb,emphysema etc)Can be seen on chest xray/ABPA (allergic bronchopulmonary aspergillosis associated with asthma and cystic fibrosis)/Invasive aspergillosis. It affects patients who are immunocompromised and those with chronic granulomatous diseases.Also produces aflatoxins associated with hepatocellular carcinoma. It is present in major recyclers, compost pits etc. Treatment- Itraconazole, Amphotericin B.
8) Candida Albicans- Microscopically it shows budding yeast cells with pseudohyphae on KOH preparation and also true hyphae. Candida into serum at 37 degrees for 3 hours lead to the formation of true hyphae from yeast called “ germ tubes”. It is also dimorphic. Most common cause of opportunistic mycoses.It causes candida vaginitis/ oropharyngeal(oral thrush) mucocutaneous and esophageal diseases.Rarely causes pneumonia. Candida Vaginitis it is thick cottage cheese discharge, pseudohyphae budding yeasts and there is vaginal inflammation. It is one of the cause of HIV associated esophagitis apart from CMV and HSV. On endoscopy- there are patches of adherent grey white membrane on the oral mucosa. Treatment- Imidazoles- Nystatin, Amphotericin B , Fluconazole. Candida is an inhabitant of GIT and oral mucosa ( uw point).
9) Cryptococcus Neoformans- Major virulence factor- It has antiphagocytic polysaccharide capsule .It forms round yeast with variable sizes and narrow based buds( can be clear with india ink, red with mucicarmine and blue on staining). Causes Cryptococcal lung disease and meningoencephalitis. It is number one cause of meningitis in AIDS patient s (uw point). It is present in soil with pigeon droppings. Latex agglutination detects polysaccharide capsule. Treatment- Amphotericin B with Flucytosine for 10 weeks and then Fluconazole.
10) Mucor Rhizopus - It is non septate filamentous fungi.On histology it is seen as broad hyphae with irregular branching and rare septations.The hyphae branch at 90 degrees Sporangiophores are inhaled. Seen in diabetic or ketoacidotic or leukemic patients.They cause rhino orbito cerebral infections and can also cause pulmonary disease especially in immune compromised people.Fungi spreads from sinuses to brain tissue. Clinical features are facial , periorbital puffiness, pain and nasal discharge. Black eschar ( necrotic tissue) on the palate is seen. Treatment- Amphotericin B, surgical debridement.
11)Pneumocystis Jervocii( P.Carini) - Silver stained cysts in tissues(Bronchial lavage).It causes bilateral symmetrical interstitial pneumonia. Pneumocystis attaches and kills type 1 pneumocytes causing excess replication of type 2 pneumocytes and damages the alveolar epithelium.It is the hallmark of atypical pneumonia of AIDS(uw point).It shows honeycomb appearance on H and E stains.And on xray it shows ground glass appearance, patchy infilterate. On silver methanamine stain disc shaped yeast is formed in lung tissue. CD 4 count drops to less than 200 cells/mm3 in HIV. Treatment- Trimethoprim,Sulfamethazole, Dapsone and pentamidine.
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