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42 Cards in this Set

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Lab 10
Recognize macroconidia and microconidia.
Lab 10
Define dimorphic fungi and state how they are usually contracted by humans.
Dimorphic fungi grow as molds out side of the body, producing hyphae and asexual reproductive spores, but inside the body they grow in a nonmycelial form. Infections usually begin by inhaling spores from the mold form.
Lab 10
Name three common dimorphic fungal infections found in the United States, state how they are transmitted to humans, and indicate where they are found geographically.
Coccidioides immitis causes coccidioidomycosis, a disease endemic to the southwestern US; the mold form is inhaled. Histoplasma capsulatum causes histoplasmosis, a disease commonly found in the Great Lakes region and the Mississippi and Ohio River valleys. It grows in bird or bat droppings or soil contaminated with these droppings and is inhaled. Blastomycosis, caused by Blastomyces dermatitidis and is common around the Great Lakes region and the Mississippi and Ohio River valleys. Also found in bird/bat droppings and is inhaled.
Lab 10
Describe the mold form and the nonmycelial form of the following:
a. Coccidioides immitis
b. Histoplasma capsulatum
c. Blastomyces dermatitidis
a. mold form produces thick-walled, barrel-shaped asexual spores called arthrospores. Nonmycelial develops into endosporulating spherules.
b. mold produces large tuberculate macroconidia and small microconidia. Nonmycelial grows as budding encapsulated yeast.
c. mycelium with small conidiospores and gerimates as a yeast having a characteristic thick cell wall.
Lab 10
Recognize Rhizopus zygospores.
Lab 9
State 3 ways fungi may be beneficial to humans and 3 ways they may be harmful.
They benefit by recycling nutrients, manufactoring industrial and food products, and producing antibiotics. They harm by damaging wood and fabrics, spoiling food, and causing diseases.
Lab 10
Describe conidiospores and sporangiospores and name a mold that produces each of these.
Conidiospores are borne externally in chains on an aerial hypha called a conidiophore (Penicillium); sporangiospores are produced within a sac or sporangium on an aerial hypha called a sporangiophore (Rhizopus).
Lab 10
Recognize the following genera of molds when observing a prepared slide under high magnification and state the type of asexual spore seen:
a. Penicillium
b. Aspergillus
c. Rhizopus
A. finger-like projections called sterigmata. Conidiospores.
B. chains on the surface of a ball-like structure called a vesicle. Conidiospores.
C. within sacs called sporangia. Sporangiospores.
Lab 10
Define dermatophyte and list three common genera of dermatophytes.
A group of molds that cause superficial mycoses of the hair, skin, and nails and utilize the protein keratin. Microsporum, Trichophyton, and Epidermophyton.
Lab 10
Name four dermatophytic infections and state how they are contracted by humans.
Tinea capitis (head), tinea barbae (face and neck), tinea corporis (body), tinea cruris (groin). Dermatophytic infections are acquired by contact with fungal spores from infected humans, animals, or objects.
Lab 10
Recognize a mold as a dermatophyte and state how you can tell when given the following:
a. a flask of DTM showing alkaline products
b. an SDA culture (under a microscope) or picture showing macroconidia.
a. As the dermatophytes utilize the keratin in the medium, they produce alkaline end products, thus turning the phenol red in the medium from yellow or acid to red or alkaline
b. the presence of macrocondia means the mold is a dermatophyte
Lab 9
Describe the appearance of Saccharomyces cerevisiae and Candida albicans on Saboraud Dextrose agar and on Mycosel agar.
Both the S cerevisiae and C. albicans grew in yeast-like formations on the Saboraud Dextrose agar but only the C. ablicans grew on the Mycosel agar.
Lab 9
When given a plate of Mycosel agar showing yeast-like growth and a plate of Rice Extract agar showing pseudohyphae, blastospores, and chlamydospores, identify the organism as Candida albicans.
Go and do likewise!
Lab 9
Recognize the following observed microscopically:
a. Saccharomyces cerevisiae and Candida albicans as yeasts in a direct stain preparation
b. A positive specimen for thrush by the presence of budding Candida albicans
c. Cryptococcus neoformans in an India ink preparation
d. A cyst of Pneumocystis carinii in lung tissue
Hop to it.
Lab 10
Define the following: hypha, mycelium, vegetative mycelium, and aerial mycelium.
The hypha is a branching, tubular structure from 2-10 µm in diameter and is usually divided into cell-like units by crosswalls called septa. The total mass of hyphae is termed a mycelium. The portion of the mycelium that anchors the mold and absorbs nutrients is called the vegetative mycelium; the portion that produces asexual reproductive spores is termed the aerial mycelium.
Lab 10
Describe macroconidia and microconidia.
Macroconidia apear as rice mixed in with substance that apears like hair (microconidia).
Lab 12
Name four strains of E. coli that may infect the gastrointestinal tract.
Enterotoxic (ETEC), Enteropathogenic (EPEC), Enteroinvasive (EIEC), and Enterohemorrhagic E. coli (EHEC).
Lab 9
Describe the typical appearance of a yeast and its usual mode of reproduction.
They are unicellular, oval or spherical fungi which increase in number asexually by a process termed budding.
Lab 9
Describe yeasts in terms of their oxygen requirements.
Yeasts are facultative anaerobes and can therefore obtain energy by both aerobic respiration and anaerobic fermentation.
Lab 9
State two ways the yeast Saccharomyces is beneficial to humans.
Are used for both baking and brewing.
Lab 9
Name two yeasts that commonly infect humans
Candida albicans and Cryptococcus neoformans
Lab 9
Name four common forms of candidiasis.
Thrush, vaginitis, onychomycosis (infection of the nails), and dermatitis (diaper rash and other infections of moist skin).
Lab 9
State the usefulness of Saboraud Dextrose agar, Mycosel agar, and Rice Extract agar.
Saboraud Dextrose agar (SDA) is selective for fungi. Mycosel agar inhibits bacteria saprophytic fungi; is selective for pathogenic fungi. Rice Extract stimulates the formation of pseudohyphae, blastospores, and chlamydospores, unique to C. albicans.
Lab 9
State how Cryptococcus neoformans is transmitted to humans, where in the body it normally infects, and possible complications.
The yeast is inhaled from dried bird feces and infects the lungs. It may spread to the blood and from there to the meninges or elsewhere, causing cryptococcal meningoencephalitis.
Lab 9
State what disease is caused by Pneumocystis carinii and indicate several predisposing conditions a person is normally seen to have before they contract the disease.
Pneumocystis carinii pneumonia (PCP). It is seen almost exclusively in highly immunosuppressed individuals such as those with AIDS, late stage malignancies, or leukemias.
Lab 12
Name the most common nonfermentative gram-negative rod that infects humans and list five types of opporunistic infections it may cause.
Pseudamonas aeruginosa may cause urinary tract infections, wound infections, pneumonia, septicimia, and burn infections.
Lab 12
Name the bacterial family to which the most commonly encountered organisms isolated from clinical specimens belong.
Lab 11
Define the following: bacteriophage, plaque, and phage typing.
Bacteriophages are viruses that infect only bacteria. Plaque is a small clear area on an agar plate where bacteria have been lysed by a bacteriophage. Phage typing is the use of known bacteriophages to id unknown bacteria.
Lab 11
Describe the structure of the bacteriophage coliphage T4
The coliphage is comprised of a capsid head containing the genome and a sheath with tails and pins.
Lab 11
Describe the lytic life cycle of the bacteriophage.
1. adsorbtion: the virus tail adsorbs to receptors on microbe
2. penetration: virus' enzymes drill into cell wall and inject genome; beg. of eclips period, e.g. no complete viruses in the microbe.
3. replication: viral. enzymes stop nucleic acid and protein synthesis, the viral genome is replicated and metabolic machinery is used to synthesize viral components.
4. maturation: viruses assemble.
5. release: viral lysozyme breaks peptidoglycan, killing the host and releasing the bacteriophage.
6. reifection: the 50-200 new viruses now infect surrounding bacteria.
Lab 11
Define viral specificity
A specific strain of a virus will only adsorb (and therefore infect) to a specific strain suseptible bacterium.
Lab 11
Recognize plaques and state their cause.
Small clear areas in a bacterial growth caused by lysis of the bacteria by bacteriophages.
Lab 11
Interpret the results of a viral specificity teat using coliphage T4.
If the coliphage causes a plaque it was able to infect the bacteria and it must be E. coli.
Lab 12
State what infections are caused by Salmonella and by Shigella and how they are transmitted to humans.
Salomella caueses slamonellosis, a disease causing diarrhea and infrequently typhoid fever, is transmited by the fecal-oral route. Shigella is also transmitted by the fecal-oral route and causes shigellosis, resulting in dysentery.
Lab 12
Name five genera of Enerobacteriaceae considered as common opportunistic pathogens, state their normal habitat, and list four common types of oppotunistic infeactions that they all may cause.
Escherichia coli, Proteus, Enterobacter, Klebsiella, Citrobacter, and Serratia are all normal flora of the intestinall tract. They can all cause urinary tract infections, wound infections, pneumonia, and septicemia.
Lab 12
Define nosocomial infections.
A hospital acquired infection.
Lab 9
Define mycology and mycosis.
The study of fungi.
The diseases caused by fungi.
Lab 12
State how to differentiate Pseudomonas aeruginosa from the Enterobacteriaceae using the following tests: A. oxidase test, B fermentation of glucose, C. production of pigment and fluorescent products, and D. odor.
a. P aeruginosa is oxidase positive the Enterobacteriaceae are negative.
b. P. aeruginosa will not ferment glucose, Enterobacteriaceae will.
c. P aeruginosa produces a green or blue water soluble pigment and a fluorescent substance, Enterobacteriaceae will not.
d. P. aeruginosa smells fruity, Enterobacteriaceae smells foul.
Lab 12
Discuss the significansce of R plasmids in our attempt to treat infections cause by the Enterbacteriaceae.
These plasmids code of antibiotic resistance and the spread of this resistance by a sex pilus; as a result of these plasmids over 50% of nosocomial infections are resistant to durgs.
Lab 13
Interpret the results of XLD agar.
XLD: Yellow indicates acid production and therefore fermentation of lactose and/or sucrose. Red indicates alkaline production from the catabolism of lysine. If sugars are fermented and lysine broken down both red and yellow will be produced. Black colonies indicates hydrogen sulfide production.
1.Escherichia coli: flat yellow colonies; some strains may be inhibited.
2.Enterobacter and Klebsiella: mucoid yellow colonies.
3.Proteus: red to yellow colonies; may have black centers.
4.Salmonella: usually red colonies with black centers
5.Shigella and Pseudomonas: red colonies without black centers
Lab 13
Interpret the results of Pseudosel agar.
Pseudomonas aeruginosa will typically produce a green to blue, water-soluble pigment and will also fluoresce.
Lab 13
Interpret the results of the following tests:
a. oxidase test (Taxo N® disc)
b. pigment production on Pseudosel agar
c. fluorescence under ultraviolet light on Pseudosel agar
d. odor
a. In the immediate test, oxidase-positive reactions will turn a rose color within 30 seconds. In delayed test, oxidase-positive colonies will turn black within 20 minutes.
b. All of the Enterobacteriaceae ferment the sugar glucose; Pseudomonas aeruginosa will not.
c. Pseudomonas aeruginosa produces a green to blue, water soluble pigment and fluorescein. Enterobacteriaceae does produces none of these things.
d. Enterobacteriaceae have a rather foul smell; Pseudomonas aeruginosa produces a characteristic fruity odor.