Fungi/Mycobacteria

ergosterol

• •eukaryotic
• most are strict aerobes
• NO strict anaerobes

• •They possess at least one nucleus
• surrounded by a  nuclear membrane

•Have chromosomes

•Have cytoplasmic organelles

•Cell membrane contains sterols (ergosterol*)

• muramic acid
• teichoic acids
• peptidoglycan

• Hexos and hexosamine polymers
• CHITIN
• glucans
• mannans

composed of gluocosamine subunits (linked like cellulose)

• Bilayered
• –Contains phosphatidylethanolamine
• (phospholipid) and phosphatidylcoline
• –Ergosterol and zymosterol – major sterols
• –Cholesterol is usually absent

• Functions as an osmotic barrier.
• Facilitates synthesis of cell wall material

organic compounds

decaying oraganic material-- will grow on simple carbon source nitrate ions as a nitrogen source

• - absorptive mode of nutrition  - secrete digesting enzymes into environment - simpler
• substances from  digested macromolecules enter cell by osmosis or specialized transport systems

- smooth colonies like   bacteria;  microscopically -  single cells which bud

• fuzzy colonies microscopically how the cell to extend by formation of tube-like extensions with thinck parallel walls called HYPEA
• Separate or non separate
• A mass of hypea= mycelium

• Fungi can grow as yeast or mold
• Some fungi can grow as either phase

Environmental factors

• Yeast-- usually found WITHIN a system so can live inside a body 
• Mold form-- room temperature

• Dimorphic fungi
• grow as budding yeast cells
• filamentous hyphae (bottom of picture)
• intermediate forms
• *most important fungi

NO

fusion of 2 nuclei that general undergo mitosis

• NO.
• asexual spores continus to maintain and disseminate these species

• = reproductive elements producers by:
• -budding off of conidiogenous hypae
• - differentiation of preformed hypae

• = reproductive elements produced by:
• -consecutive cleavages of a sporangium
• -major method for maintenance and dissemination of many fungi*

formation of a bud in yeasts

produce separate or non separate hyphae which extend to from a mycelium

• branching tubular structures that make up the mycelium
• septae divide the hyphae into compartments (not cells)

• considered more primitive.
• when hyphal strand is damaged, entires strand dies!
• 

• pores between adjacent compartments can be plugged preventing death of entire strand
• 

based on sexual spores and septation

• gametes and asexual reproduction with the formation of zygospores
• Aspetate
• Asexaul spore: Sporangiospore

• ascus with the production of ascospores
• Septate
• Asexaul spore: Conidia

• basidium with the production of basidospores
• Septate
• Asexaul spore: Conidia

• no recognizable form of sexual reproduction
• Asexaul spore: Conidia
• Septate

• Mucor
• Rhizoporus

• -Blastomyces
• -Dermatophytes
• -Histoplasma capsulatum
• -Candida
• -Aspergillus

Crytococcus neoformans

Fusarium

• Superficial skin fungi
• indolent lesions of the skin and its appendages
• Ex: ring worm, athlete's feet

• systematic pathogens
• can caused serious progressive disease in previously healthy people

• most are oppurtunistic
• 1000/s of aerosol conidia and spores inhaled daily
• some are normal flora
• systematic infections= uncommon
• progressive systematic fungi infections= most difficult to diagnosis and therapeutic problems in infectious disease (esp in immunocompromised)
• spores/components= could be allergen. sting hypersensitivity rxn does not require growth or viability of the fungus

• adherence
• invasion
• extracellular enzymes
• phagocytic interactions
• tissue injury
• immmunity

• Some yeasts can colonize mucosa of GI/UG
• require surface adhesion on the microbe and a receipt on the epi cell

• across surface barrier.
• may be though mechanical breaks in epithelium

C. albicans-- form hyphae and pseudohyphae that allow penetration and spread (mechanism unknown)

• proteases
• elastases

- neutrophils and macrophages are able to kill hyphae of most fungi

-dimorphic species are more resistant to killing by neutrophils

• C. albicans
• yeast @ 25d C
• hyphae @ 37d C

• contanins component in the call of its conidial (infective phase that is antiphagocytic
• hyphae convert to a spherule phase in tissue and become resistant

• - none of the extracellular products of
• opportunistic fungi have been shown to injure the host directly

• - exotoxins / mycotoxins are produced in the environment by a number of fungi but not in
• vivo

• - injury caused by fungal infections is due to
• the inflammatory and immune responses
• stimulated by the prolonged presence of the fungus.

• intact immune response prevents infection by fungi and progressive disease
• T-cell mediated response of Primary importance
• progressive fungal diseases occur in immunocompromised patients

-opsonizing antibody effective in some yeast infections

• Cryptococcus neoformans -antibody controls infection
• enhances killing by phagocytes   
• capsule of C. neoformans antiphagocytic - antibody to capsule similar to encapsulated bacterial pathogens

• systematic disease associated with deficiencies in neutrophils and T-cell mediated immunity
• fungi that escapee neutrophils grow slowly in macrophages

• O2: (most= aerobic)
• temp : mesophilic
• Moisture: 75-95% humidity
• pH tolerance: 5-6 optimal
• Generation time: yeasts= 2-3 days. molds= 1-3 WKS

◦ traditional growth media for fungi

◦ peptone, dextrose at pH 5.6

◦low pH retards growth of many bacteria

• ◦NOT the best medium because it SUPPRESSES
• conidiation and PROMOTES MYCELIAL GROWTH

SUPPRESSES conidiation PROMOTES MYCELIAL GROWTH

SDA with chloramphenicol

◦ isolate clinical fungal specimens

• ◦ same as SDA but with chlormephenicol actidione
• (cycloheximide)

◦ @ pH 6.8

◦ used to isolate dermatophytes from clinical skin and nail specimens

• ◦ contains cycloheximdes, gentamycin, and
• chlortetracycline to suppress common bacteria and non-fermatophilic fungi

• nutrient enriched
• primary to grow yeast cultures especially with dimorphic fungi

deficient medium used to stimulate sporulation of many fungi

most commonly used to induce condition of fungi that do not produce sufficient spores on SDA, DTM, or Mycosel

• Mold ID
• microscopic characteristic of fungi
• direct microscopic examination of skin scrapings

• Mold ID 
• lactophenol cotton blue 
• miscroscopic examination of cultures

ID by sugar fermentation, sugar assimilation and some biochemical patterns

• Direct examination of pus, fluid, or tissues
• 10 – 20% KOH
• Heat slide and observe under microscope
• Use 20X or 40X magnification
• Fungi remain intact while tissue cells are disrupted
• Culture - use media containing antibacterial antibiotics

hyphae

• fungus
• inflammation

stain all fungi and are very helpful for detection of fungi in tissue sections

• 1. Allergy - IgE - mold allergy Non-complicated Type I
• 2. Toxins - Aflatoxins
• 3. Disease - mycosis