Molds of Medical Importance Notes Final PDF

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Dr. Colby...

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Molds of Medical Importance Molds

Mold Classification Examination of the hyphae enables classification into 3 groups: 1. Septate unpigmented hyphae (hyaline). Includes the majority of medically important molds. 2. Septate brown pigmented hyphae (dematiaceous) 3. Aseptate wide hyphae, characteristic of the order Mucorales, lower fungi sometimes called pin molds.

Hyaline Hyphae

Hyaline Molds: Aspergillus  Smoky, gray/green fuzzy colonies  Invasive infections in severely immunocompromised patients, especially with prolonged neutropenia. Mortality > 50%  Cause chronic sinusitis and aspergilloma (fungus ball in preexisting pulmonary cavity) in immunocompetent patients  Treated mortality is still more than 50%, not natural history mortality  These spores are everywhere; desks and laptops  Sinuses don’t drain properly- may can sinusitis aspergillus  Cavity in lung, can get a fungus ball growing there- doesn’t mean you are sick Hyaline Molds: Aspergillus species 1. Aspergillus fumigatus also causes allergic bronchopulmonary aspergillosis in asthmatics and CF patients 2. Aspergillus niger commonly causes otomycosis 3. Aspergillus flavus may infect immunocompromised patients and also infects peanuts, producing aflatoxin which is associated with liver carcinoma 4. Aspergillus terreus

Aspergillus fumigatus         

Branches that end up going the same way Repeated 45 degree branching, going parallel in the end. This is invasive. Tunneling its way through. Hallmark of aspergillus Need to do a silver strain Lots of things in nature exhibit this pattern To get this contrast, you need to do silver stain. Lots of things in nature exhibit this directionality. If you observe flock of birds (all coordinated and turn at same time) Sense of what the rest are doing

Aspergillus fumigatus   

Fruiting head of aspergillus fumigatus Root of the word “to fumugate” à fill a house with smoke to get rid of rodents Looks like a torch- why its called fumigatus

Aspergillus Niger  Reminds him on 1960’s poster. “have a nice day”

Hyaline Molds: Penicillium  Rapidly growing greenish colony which you often see on moldy bread  Source of penicillin  One invasive species, Penicillium marneffei  Contaminanting Alexander Flemings staphococcal species in the late 1980s  ”Why don’t the bacteria grow close to the mold?” à Maybe they produce a water soluble substance that’s inhibits bacterial growth  Source of antibiotics (penicillin)  Green colony that you see in moldy bread.  Volatile organic compounds or not??  Are the hyphi already spreading through the entire loaf or is it producing organic compounds at end  Famous mold that was contaminating Alexdander Flemming’s staphylococcal cultures in the 20’s he stared at it and asked himself, “why don’t the bacteria grow close to the mold”. They keep thei distance. Why?  Maybe they produce water soluble substance that inhibits bacterial growth and if they did that we can find out what it is , purify it and give it too people when they got bacterial infection and understated Paul ernix.  Names it penicillin because it grew from penicillium.

Dermatophytes  Trichophyton spp.  Microsporum spp.  Epidermophyton floccosum  Cause skin and skin structure infections  these spores tend to be anywhere where people walk around barefoot  Athletes foot

Trichophyton Funny cigar bodies.

Microsporum

Epidermophyton Floccosum Antlers Tinea Pedis (Athlete’s Foot)  All produce dermatophyte infections  Tinea: dermatophyte infection of .. o Need bare feet to develop  Lipids in toe jam.  Antifungal lipids are in the greatest concentration between big toe and the second toe  Decrease concentration as you move laterally  Athletes foot always start where the lipids have the lowest concentration (between little toe and ring toe) 

Streptococcus pyogenes: most common cause of cellulitis àHow does it get into the skin? àSkin keeps liquids in and keeps infections out, impermeable

Tinea Corporis (Ringworm)  Central healing and scaling  Dermatophyte infection of the body  Can be big and ugly  Since the middle ages (ringwork)  Nothing to do with worms  But they thought it was a worm  Synthritphical with central healing and scaling --> dramatified infection of the body  Quiet big and ugly looking but not invasive Kerion Most severe type of tinea capitus is a lesion of the scalp- results in hair loss, and scarring/ loss of hair folices Swab this area if huge mass of mycelium...