Veterinary Microbiology With Dr. Hoyer Exam 2 Uiuc

Front 1

T/F
Fungal cell walls are made of peptioglycan

Back 1

False; fungal cell walls contain chitin

Front 2

Fungal species are either _________ aerobes or __________ aerobes

Back 2

obligate; facultative

Front 3

Are all fungi pathogenic?

Back 3

No, very few (100) species of an estimated 1.5 million are pathogenic

Front 4

What are two basic growth forms of fungi?

Back 4

single cellular (yeast)
multicellular (mold)

Front 5

How do yeast reproduce?

Back 5

Either by budding or by fission

Front 6

What characteristics are used to classify fungi taxonomically?

Back 6

the type of spore formed in the sexual state

Front 7

Name the three categories of fungi based on spore type

Back 7

zygospore
ascospore
basidiospore

Front 8

Sexual stage : Teliomorph
Asexual stage : ?

Back 8

Anamorph

Front 9

In which category are fungi that have no known sexual state?

Back 9

Fungi imperfecta (deuteromycetes)

Front 10

How would one determine if an infection is fungal in nature?

Back 10

clinical signs, appearance of lesions, direct microscopic examination of material from lesion, culture and isolation of fungus from lesion

Front 11

How is Sabouraud agar a selective medium?

Back 11

The low pH (5.6) allows for the growth of fungi while killing bacteria

Front 12

Under which conditions would you grow fungi in culture, air or CO2?

Back 12

Air, because all fungi are aerobic and will therefore grow best in O2-rich environments

Front 13

What is the purpose of adding cycloheximide to Sabouraud agar?

Back 13

Cycloheximide prevents the growth of saprophytic fungi

Front 14

What is the purpose of adding chloramphenicol to Sabouraud agar?

Back 14

Chloramphenicol prevents the growth of bacteria

Front 15

What is the drawback to adding antibiotics to Sabouraud agar?

Back 15

Some fungi are susceptible to antibiotics, so the fungus in question may be inhibited from growing

Front 16

hypha (pl. hyphae)

Back 16

a branching tubular structure that forms the vegetative body of a growing filamentous fungus

Front 17

mycelium (pl. mycelia)

Back 17

a mass of hyphae

Front 18

aerial mycelia

Back 18

a mass of hyphae that rises above the agar surface

Front 19

pseudohyphae

Back 19

chains of budding yeast that fail to separate thus giving the appearance of hyphae

Front 20

septum (pl. septa)

Back 20

a division between successive hyphae

Front 21

ceonocytic

Back 21

hyphae that lack dividing septa

Front 22

yeast

Back 22

single cellular fungus

Front 23

mold

Back 23

multicellular fungus with entangled hyphae

Front 24

Dimorphic

Back 24

describes a fungus that grows as a mycelium in the environment but as a yeast in the host

Front 25

What is the usual trigger for dimorphic changes?

Back 25

an ambient temperature of 37C is the usual trigger for growth of a yeast form versus a mycelial form

Front 26

Do all fungi grow in culture?

Back 26

No, not all fungi grow in culture.

Front 27

T/F
culture conditions rarely have an effect on morphology of a fungus

Back 27

False; culture conditions can greatly affect the morphology of a fungus (temperature, pH, oxygen content)

Front 28

What is (possibly) the best method for diagnosing a fungal infection?

Back 28

direct microscopic examination of clinical specimen

Front 29

What are dermatophytes?

Back 29

fungi that live in superficial keratinized structures

Front 30

Where are dermatophytes found?

Back 30

Dermatophytes are found on humans (anthropophilic), animals (zoophilic), and soil (geophilic)

Front 31

Are dermatophytes zoonotic?

Back 31

Yes, dermatophytes are easily transmitted from animals to humans

Front 32

Which are the perfect dermatophytes?

Back 32

Arthroderma and Nannizzia

Front 33

Which are the imperfect dermatophytes?

Back 33

Microsporum, Trichophyton, Epidermophyton

Front 34

Which dermatophytes are the most important in veterinary medicine?

Back 34

Microsporum, Trichophyton

Front 35

What morphology of a dermatophyte will be seen in a skin scraping?

Back 35

hyphae will be seen since they grow in the superficial layers of the skin

Front 36

In which layer of epidermis do dermatophytes grow?

Back 36

stratum cornium

Front 37

Arthrospore

Back 37

a spore that results from the segmentation of existing hyphae at their septa

Front 38

Endotrhix

Back 38

an arthrospore that grows inside the hair shaft

Front 39

Ectothrix

Back 39

an arthrospore that grows on the outside of the hair shaft (but may be found inside the hair shaft at the same time)

Front 40

Describe the morphology of Microsporum macroconidia.

Back 40

rough-walled, has many internal septa, hook on the end

Front 41

Describe the morphology of Trichophyton macroconidia.

Back 41

smooth-walled, has fewer internal septa, no hook on the end

Front 42

T/F
Dermatophyte species in clinical specimens are easy to differentiate.

Back 42

False
skin scrapings from lesions will have the same morphologies (septate hyphae, arthrospores) regardless of species

Front 43

What are the clinical signs of a dermatophyte infection?

Back 43

puritis, alopecia, dermatitis, severe crusting lesions, sometimes a secondary bacterial infection

Front 44

T/F
Many hosts will not have clinical signs of a dermatophyte infection

Back 44

True
many hosts will not have clinical signs

Front 45

From which area of a ringworm lesion would viable fungal elements be acquired?

Back 45

from the outer inflamed margin of the lesion

Front 46

dermatophytid

Back 46

a hypersensitivity reaction to a dermatophyte that leads to lesions spread in vesicles throughout the body ("id" lesions)

Front 47

What methods are used to arrive at a diagnosis of a dermatophyte infection?

Back 47

skin scrapings, Wood's light, culture and isolation, direct microscopic identification of arthrospores in/on the hair shaft

Front 48

What morphological features of dermatophytes are seen in clinical specimens?

Back 48

septate hyphae, arthrospores

Front 49

What morphological features of dermatophytes are seen in culture?

Back 49

microconidia, macroconidia, mycelia

Front 50

What treatments are available for dermatophyte infections?

Back 50

griseofulvin, Whitfield's ointment, itraconazole

Front 51

What is the predominant pathogenic species of Aspergillus?

Back 51

Aspergillus fumigatus

Front 52

T/F
The optimal growth range for Aspergillus is 30-50C

Back 52

False; optimal growth range is 30-37, but Aspergillus can grow up to 50C

Front 53

Describe the yeast form of Aspergillus in clinical specmens.

Back 53

There usually is no yeast form in clinical specimens

Front 54

T/F
mature conidiophores will arise on Aspergillus species that are in host tissues

Back 54

False (mostly); Aspergillus must be in an oxygen-rich environment for mature conidiophores to form (could form conidiophores in air sacs or nasal cavity)

Front 55

Put these in order starting from the hypha: sterigmata, conidiophore, foot cell, hypha, condidia, vesicle

Back 55

hypha, foot cell, conidiophore, vesicle, sterigmata, conidia

Front 56

What is the infectious form of Aspergillus?

Back 56

the conidia

Front 57

What morphological forms of Aspergillus can be detected in clinical specimens?

Back 57

mycelia/hyphae in tissue sections

Front 58

What morphological forms of Aspergillus are seen in culture?

Back 58

mature conidiophores with conidia are seen when grown in oxygen-rich environment

Front 59

What veterinary species does aspergillosis affect?

Back 59

birds (poultry, caged birds); can affect adults, chicks and eggs

Front 60

How does Aspergillus create lesions in the host?

Back 60

direct invasion of hyphae through blood vessels and into tissues

Front 61

How is a definitive diagnosis of aspergillosis made?

Back 61

visualization of hyphae in tissue sections treated with 10%KOH; isolation and culture

Front 62

What are aflatoxins?

Back 62

toxins produced by certain strains of Aspergillus species when grown on feed in certain temperatures and humidities

Front 63

What is the most important pathogenic species of Candida?

Back 63

Candida albicans

Front 64

Where is Candida found?

Back 64

commensal of oral cavities, GI tract, reproductive tract

Front 65

What disease of veterinary importance is produced by Candida?

Back 65

Thrush in birds

Front 66

What are the clinical signs of a Candida infection in birds?

Back 66

white/grey pseudomembranous lesions of mucous membranes of GIT; lesions may slough leaving ulcers

Front 67

Describe the morphology of Candida in culture.

Back 67

yeast with pseudohyphae; if hyphae grow they are septate; gram positive

Front 68

What is the fastest growing fungi studied in these lectures?

Back 68

Candida--has a generation time almost equal to E. coli

Front 69

Describe the morphology of Candida in clinical specimens.

Back 69

mixture of yeast, pseudohyphae, septate hyphae

Front 70

What test can give a definitive diagnosis of Candida infection?

Back 70

germ tube test

Front 71

What is the natural habitat of Cryptococcus neoformans?

Back 71

found in pigeon droppings

Front 72

A fungal species was found in bird droppings. Does this mean the bird is infected? why or why not?

Back 72

the bird probably isn't infected. Fungus (cryptococcus, histoplasma) can be blown into bird droppings and then begin growing due to high levels of creatinine

Front 73

How does C. neoformans enter a host?

Back 73

inhalation of basidiospores is most common; can be transmitted via direct contact with broken skin

Front 74

Describe the morphology of Cryptococcus neoformans in culture.

Back 74

yeast at room temperature and at 37C (NOT A DIMORPHIC SPECIES); spherical or ovoid yeast; very thick capsule

Front 75

Describe the morphology of C. neoformans in clinical specimen

Back 75

yeast form

Front 76

Virulence factors of C. neoformans include (choose all that apply): thick capsule, pili, degradative enzymes, aflatoxins, phenoloxidase, growth at 37C

Back 76

thick capsule, degradative enzymes, phenoloxidase, growth at 37C

Front 77

What is the natural habitat of Blastomyces dermatitidis?

Back 77

soil in areas with high humidity and near waterways

Front 78

What are the morphologial features of Blastomyces in culture?

Back 78

yeast at 37C on blood agar: globose, thick walls, mother and daughter of equal sizes
mold at room temp on Sabouraud agar: pyridiform conidia

Front 79

Describe the morphological features of Blastomyces dermatitidis in clinical specimens.

Back 79

yeast in pus, sputum or tissues; mother and daughter cells of equal size

Front 80

What species are usually affected by blastomycosis?

Back 80

humans, dog, Siamese cats, sea lions, horses

Front 81

Does a host need to be immunocompromised to contract blastomycosis?

Back 81

No, Blastomyces dermatitidis can affect normal, healthy animals

Front 82

What are the clinical signs of blastomycosis?

Back 82

skin lesions, SQ infection
in dogs: miliary lesions in lungs-->coughing, can affect bones (coughing dog with a limp)

Front 83

How does Blastomyces dermatitidis enter a host?

Back 83

inhalation of conidiospores (most common), animal bites, needle sticks, venereal transfer

Front 84

What is the best way to culture a clinical sample to confirm a Blastomyces infection?

Back 84

Sabouraud agar at 25-30C for 3-4 weeks to allow for mycelial growth

Front 85

What is the natural habitat of Histoplasma capsulatum?

Back 85

Soil in the Ohio and Mississippi River Valleys

Front 86

Which fungal species are you likely to isolate from a bat cave?

Back 86

Histoplasma capsulatum

Front 87

Describe the morphological features of Histoplasma capsulatum in culture.

Back 87

Sabouraud agar at room temp: septate hyphae with 2 types of conidia
blood agar at 37C: yeast

Front 88

Describe the macroconidia of Histoplasma capsulatum.

Back 88

large, round, thick-walled, knob-like projections from the surface

Front 89

Describe the morphology of Histoplasma capsulatum in clinical specimens.

Back 89

yeast-like cells within host macrophages and monocytes

Front 90

Which fungal species is the slowest growing of those studied in class?

Back 90

Histoplasma capsulatum; will take up to 10 weeks to see growth on Sabouraud agar

Front 91

What are the clinical signs of histoplasmosis?

Back 91

usually unapparent or self-limiting; most lesions are in the lungs--coughing, difficulty breathing; chronic cases can have ascites, enlarged lymph nodes, GI disorders

Front 92

What is the natural habitat of Coccidioides species?

Back 92

hot, desert soil in the Southwestern US and Central and South America

Front 93

Hos does Coccidioides enter a host?

Back 93

inhalation of arthroconidia

Front 94

T/F
Coccidioides requires a strict temperature shift to cause a dimorphic shift

Back 94

False; a temperature range of 34-40C is sufficient enough to induce dimorphic change in Coccidioides

Front 95

What are the two phases in the life cycle of Coccidioides species?

Back 95

saprophytic phase in the environment
parasitic phase in the host

Front 96

Spore forming branches at right angles to hyphae are characteristic of which fungi?

Back 96

Coccidioides species (make Y, L shaped branches)

Front 97

What is formed in the host after inhalation of Coccidioides arthroconidia?

Back 97

spherules containing uninucleate endospores

Front 98

Describe the morphology of Coccidioides in culture.

Back 98

Coccidioides should not be cultured because it is highly contagious! will have septate hyphae and arthroconidia

Front 99

Describe the morphology of Coccidioides in clinical specimens.

Back 99

mixture of spherules and hyphae in purulent material

Front 100

What morpholoogical form of Coccidioides must be observed in clinical specimens for a definitive diagnosis? Why?

Back 100

Mature spherules. Immature spherules look like fat globules

Front 101

What are the clinical signs of coccioiomycosis?

Back 101

usually asymptomatic; coughing, chest pain, fever; can have lesions in lungs, brain, liver, kidney, bones, spleen

Front 102

Name the two types of fungal infections that should be treated and how they are treated.

Back 102

superficial mycoses: topical, systemic (oral, injectable)
deep-seated mycoses: systemic (oral, injectable)

Front 103

What differences between fungi and mammalian cells are exploited in antifungal therapies?

Back 103

cell wall in fungi
fungal cell membrane made of ergosterol

Front 104

What is the mechanism of action of griseofulvin?

Back 104

disrupts mitotic spindle structure in fungal cells to prevent mitosis

Front 105

What is the mechanism of action of amphotericin B?

Back 105

binds ergosterol and inserts into the fungal cell membrane creating a pore which distorts the membrane and causes leakage

Front 106

What is the mechanism of action of flucytosine?

Back 106

acts as an antimetabolite thereby replacing uricil in the RNA pool; also inhibits thymidylate cyclase thereby stopping thymidine synthesis for DNA use

Front 107

What is the mechanism of action of the azoles?

Back 107

Inhibit ergosterol synthesis--stores are depleted, metabolites build up, damage to cell membrane

Front 108

What is the mechanism of action of echinocandins?

Back 108

inhibit synthesis of cell wall component beta-1,3-glucan

Front 109

What is the mechanism of action of the allylamines?

Back 109

inhibit ergosterol synthesis

Front 110

intrinsic resistance

Back 110

inherent traits that confer resistance to drugs

Front 111

acquired resistance

Back 111

traits that confer resistance that develop over the course of drug therapy

Front 112

Name some drug resistance mechanisms of fungi.

Back 112

decreased drug uptake, alter target enzyme, increase expression of target enzyme genes, amplification of target enzyme genes

Front 113

What are some new approaches to antifungal therapies?

Back 113

chitin synthase inhibition, tRNA synthetase inhibition

Front 114

What are transition bacteria?

Back 114

gram positive, acid-fast, filamentous bacteria that have morphologies similar to fungi

Front 115

Which bacteria genera are included in transition bacteria?

Back 115

Actinomyces, Arcanobacterium, Norcardia, Dermatophilus, Streptomyces

Front 116

What diseases does Actinomyces bovis casue?

Back 116

lumpy jaw in cattle, poll evil, fistulous withers, pulmonary/abdominal/visceral actinomycosis

Front 117

What diseases does Actinomyces viscosus cause?

Back 117

periodontal disease, canine pulmonary actinomycosis, cutaneous granulomatous abcesses

Front 118

What diseases are associated with Aracanobacterium pyogenes?

Back 118

supperative lesions in swine and ruminants

Front 119

What diseases are caused by Norcardia?

Back 119

bovine mastitis, pulmonary norcarditis, supperating granulomatous lesions

Front 120

What diseases are caused by Dermatophilus congolensis?

Back 120

exudative dermatitis, cutaneous streptothricosis, lumpy wool, strawberry foot rot

Front 121

Where are transition bacteria naturally found?

Back 121

commensals of oropharynx, reproductive tract, some are soil-dwelling

Front 122

How do transition bacteria enter the host?

Back 122

licking wounds, through dental alveoli, inhalation

Front 123

How do you perform an acid-fast stain?

Back 123

flood slide with carbo-fuschin stain then heat for 3-5 minutes; decolorize with acid-alcohol; couterstain

Front 124

What makes an acid-fast cell acid-fast?

Back 124

Carbo-fuschin remains bound to myecolic acids in the cell membrane and are not removed during decolorization

Front 125

What color are acid-fast cells?

Back 125

reddish-pink

Front 126

What are sulfur granules?

Back 126

aggregates of transition bacteria held together by polysaccharide-protein complexes

Front 127

Which transition bacteria genera produces an abundance of natural antibiotic compounds?

Back 127

Streptomyces species

Front 128

What differences between bacterial cells and mammalian cells are exploited in antibacterials?

Back 128

DNA synthesis mechanisms, cell wall synthesis, protein synthesis mechanisms, cell membrane function

Front 129

What effect does a change in extracellular cation concentrations have on antibacterial drugs?

Back 129

alters the charge on the surface of the drug so that it cannot be taken up into the bacterial cell

Front 130

What purpose does a change in environmental pH serve to bacteria as a means of antibacterial resistance?

Back 130

a change in pH can inactivate a drug

Front 131

Bacteriostatic

Back 131

inhibition of growth/proliferation of bacteria

Front 132

bacteriocidal

Back 132

killing of bacteria

Front 133

What is MIC and how is it measured?

Back 133

MIC: minimum inhibitory concentration; minimum amount of a drug required to inhibit bacterial growth; measured by the diffusion test

Front 134

What is MBC and how is it measured?

Back 134

MBC: minimum bacteriocidal concentration; minimum amount of a drug required to kill bacteria; measured by the dilution test

Front 135

Where is genetic material found in bacteria?

Back 135

in the single circular chromosome and in extracellular plasmids

Front 136

Transformation

Back 136

uptake of free DNA by competent cells

Front 137

conjugation

Back 137

direct transfer of genetic material between two bacterial cells (i.e. via pili)

Front 138

Transduction

Back 138

transfer of genetic material into a bacterial cell via a virus or bacteriophage

Front 139

transposable elements

Back 139

genetic material that is moveable within the genome

Front 140

integrons

Back 140

genetic cassettes that can be inserted into the genome

Front 141

Which fungi are dimorphic?

Back 141

Blastomyces dermatitidis, Histoplasma capsulatum, Candida albicans, Coccidioides species

Front 142

Which fungi grow only as a yeast?

Back 142

Cryptococcus neoformans

Front 143

Which fungus grows only in mycelial form?

Back 143

Aspergillus fumigatus, dermatophytes