export_bact 5 Flashcards
grow as mononucleated single cells, pathogenic yeasts reproduce by budding (called blastospores), may produce elongated forms that resemble hyphae (pseudohyphae), colony is typically “moist”
Yeast
grow as multicellular and multinucleate filamentous colonies, reproduce by sporulation, body: hyphae (may be septate or aseptate)
Mold
occur in both mold and yeastforms
Dimorphis fungi
method of reproduction for fungi (the processof forming spores)
sporulation
the tubular, branching, multinucleatestructures that form the “body” of the mold
hyphae
hyphae having crosswalls
septate hyphae
few or no crosswalls
aseptate hyphae
a mass of interwoven hyphae
mycelium
sexual reproductive (perfect)state of fungi
Teleomorph
asexual reproductive (imperfect) state offungi
anamorph
large (usually greater than 4x12 microns)multi-celled spores, the large spores that are producedby Microsporum canis that are so characteristic that they aid in speciesidentification
Macroconidia
small (usually less than 5 microns) one-celledspores
microconidia
asexual spores produced by segmentation(fragmentation) of hyphae (characteristic of Coccidioides immitis innature and the dermatophyte in vivo), the term for thetype of fungal spores that are produced by segmentation of the hyphae
arthrospores
asexual spores produced by budding from amother yeast cell (e.g. Cryptococcus neoformans ), thetype of spores that are produced from Cryptococcus neoformans
blastospores
main component of cell wallof fungi , N-acetyl glucosamine residues, the periodic-acid-schiff stain is useful for its ability tostain this compound
chitin
D-glucose resides
glucan
cytoplasmic membrane, contains ergosterol, the name for the fungal structure that corresponds to thecytoplasmic membrane of bacteria
plasmalemma
majorsterol in cytoplasmic membranes, alters permeability, thiscompound is in the plasmalemma but not in mammalian cell structures
ergosterol
The type of spores that are produced by yeasts are called
blastospores
Dimorphic fungi have the ability to grow inthese two fungal forms
Mold & Yeast forms
Hyphae with crosswalls
Septae
Sexual reproductive ( perfect ) state offungi
teleomorph
The type of fungal spores that are produced by segmentation of thehyphae are
arthrospores
Term used in reference to Arthrospores being formedinside the hair shaft
endothrix
Term used in reference to Arthrospores beingformed outside the hair shaft
ectothrix
This compound is a structural component of thecell wall of fungi but not of bacteria
chitin
The name used for the fungal structure thatcorresponds to the cytoplasmic membrane of bacteria
plasmalemma
This compound is in the Plasmalemma but not inmammalian cell structures
ergosterol
The Plasmalemma is equivalent to what structure in bacteria
cytoplasmic membrane
The type of cell structure characteristic of the fungi
eukaryotic
toxic mushrooms belong to this class of fungi
Basidiomycetes
most members of deuteromycetes are placed in this class when their “perfect state” is delineated
Ascomycetes
this form class contains most of the fungi pathogenic to animals
Deuteromycetes ( Fungi imperfecti)
The Domain to which the fungi belong
Eukarya
The kingdom to which the fungi belong
Fungi
The toxic mushrooms belong to this class of fungi
Basidiomycetes
Most members of Deuteromycetes are placed in the class when their”perfect state” is delineated
Ascomycetes
This Form class contains most of the fungi pathogenic to animals
Deuteromyecetes
Most of the pathogenic fungi as isolated from animals have been placedin this subdivision of the fungal classification system
DEUTEROMYCOTINA(Deuteromycetes)
This agent, a common cause of “Phycomycosis”, may not be afungi but may be a member of the kingdom Protista
Pythium insidiosum
This “fungus” does not have chitin in the cell wall
Pythium insidiosum
intoxicationdue to ingestion of toxic metabolites that are produced by the action ofcertain molds in some food products
Mycotoxicosis
produce aflatoxinsthus causing aflatoxicosis, genus of fungi is one ofthe genera commonly implicated in mycotoxicosis , most common fungal species isolated from guttural pouch mycosis in thehorse Term
Aspergillus
produces aflatoxins, mostprobable exudate in a nasal discharge in a dog presenting with a nasaldischarge
Aspergillus flavus
An infection that involves the epidermal layers of skin, hair and nails
Dermatophytosis
A subcutaneous granulomatous abscess thatspreads to adjacent soft tissue, fascia and bone
Mycetoma
An intoxication due to ingestion of toxicmetabolites produced by the action of certain molds on some food products
Mycotoxicosis
These two genera of fungi are commonly implicated in mycotoxicosis
Aspergillus &Fusarium
This species of fungi is known to produce toxins which causemycotoxicosis in animals
Aspergillus fumigates
What is the major target organ in acute aflatoxin poisoning in animals?
liver
used to visualize capsulesof yeasts
India ink
best stain to visualize fungi from culture growth
Lactophenol CottonBlue
the best way to visualizethe fungal cell wall in histopathology
Periodic-Acid-Schiff (P.A.S.) stain
base media used to growfungi
Sabouraud’s Dextrose Agar
antibiotic present in Sabouraud’s DextroseAgar, inhibits nonpathogenic fungi
Cycloheximide
almost specific for isolation ofdermatophytes, contains antibiotics: cycloheximide, gentamicin, andchlortetracycline, indicator: phenol red, red color indicates alkaline
Dermatophyte test medium (DTM)
The best stain to visualize the fungal cellwall in histopathology
PAS
You have submitted a tissue specimen to a diagnostic laboratory. You request that they stain a histopathologicslide specifically for fungi. They wouldprobably use this stain
Periodic-Acid-Schiffstain
The periodic-acid-Schiff stain is useful forstaining fungi because it reacts specifically with this compound in the fungalcell wall
chitin
You are taking a skin scraping for culture ofa dermatophyte from a dog. What is therecommended incubation temperature for this specimen?
25 C
The base media usually used to grow fungi
Sabourauds Dextrose Augar
This drug is commonly added to media used togrow pathogenic fungi to keep other contaminating fungi from growing
Cycloheximide
The best stain to visualize fungi from culturegrowth
Lactophenol Cotton Blue
Used to visualize capsules of yeasts
India ink
termused by physicians to refer to a fungal infection of keratin in specific bodyareas
Tinea
termused for dermatophytes whose major source to the animal is the soil
Geophilic
humansare the maintaining host of these types of dermatophytes
Anthropophilic
the large spores that areproduced by Microsporum canis that are so characteristic thatthey aid in species identification
Macroconidia
most common cause ofdermatophytosis in the cat
Species Microsporum canis
geophilic fungusspecifically affects the keratinized skin layers with subsequent diseasedevelopment in the dog
Species Microsporum gypseum
8 month old Yorkshire-crosspigs in Georgia with large scaly lesion on his sides clinically diagnosed withdermatophytosis is most likely infected with this fungi
Species Microsporum nanum
this agent is the commoncause of skin disease involving only the dermal layers in horses
Species Trichophyton equinum
T erm used for dermatophyteswhose major source to the animal is the soil
geophilic
Humans are the maintaining host of these typesof dermatophytes
anthropophilic
Animals are the maintaining host of thesetypes of dermatophytes
zoophilic
Term used by physicians to refer to a fungalinfection of keratin in specific body areas (from PwrPt)
tinea
The large spores that are produced by Microsporum canis that areso characteristic that they aid in species identification are called
macroconidia
This dermatophyte is classified as geophilic
Microsporum gypseum
What is the pathological process responsible for the “ringworm” nature ofsome dermatophyte infections?
Lateral Growth of Fungus to avoid inflammatoryresponse
The major cause of dermatophytosis in cats
Microsporum canis
This dermatophyte is considered to be host-adapted to cats
Microsporum canis
Microsporum canis
- Symptoms: Lesions of”scaling and patching” on head and paws
- Laboratory: Direct mount of hairs in 30% KOH,arthrospores observed external to hair shaft
Microsporum canis
You have diagnosed a “ringworm” infection in a cat. The client asks about the possibility oftransfer of the infection to her or her children. You advised her that the “ringworm”in the cat, in regards to the possibility of transfer to humans, is:
a disease of highdanger to exposed individuals
This geophilic fungus specifically affects the keratinized skin layerswith subsequent disease development in the dog.
Microsporium gypseum
Most common cause of dermatophytosis in the dog
Microsporium canis
This keratinophilic fungus is host-adapted to the horse
Trichophyton equinum
Most common cause of dermatophytosis in cattle
Trichophytonverrucosum
Animals: 8 month oldYorkshire-cross pigs in Georgia
- Symptoms: Large scaly lesions onsides
- ClinicalDiagnosis: Dermatophytosis
Microsporium nanum
What is media are usually used for isolating the dermatophytes in aveterinary practice laboratory?
Saboraud’s dextroseaugar/ dermatophyte test media
Under what circumstances would you clip the hair of the animal?
Catteries, householdsw/ small children, elderly people or immunosuppresed people or long-haired cats
What is the author’s favorite antimicrobial for treating cats?
Iatroconazole
What is the major toxicity associated with ketoconazole in cats?
hepatotoxicity
Wood’s Lamp Fluorescence is often helpful indetecting the presence of this dermatophyte
Microsporum canis
Medium most commonly used be veterinarians to culture dermatophytes.
DTM
What “signs” in DTM cultures indicate that the fungus growing on themedium is a Dermatophyte?
The medium is red,the colony is white, the medium turns red at the time of 1 st visiblegrowth
You have a client that is having a continuing problem with dermatophyteinfections in her cats / dogs / horses. She wants to vaccinate to prevent the disease in her animals. You couldrecommend:
the products listedwould not be effective, are not available for the listed disease or should notbe used in this situation
What are the 3 major phases in treatment of a dermatophyte infection?
1) Remove organism fromouter layers of skin & hair,
2) Apply a topical agent
3) Systemic therapy
These two drugs from different families wouldbe most useful in treatment of a Microsporum canis infection in a cat.
Grisofulvin & Iatraconazole
This agent should not be used in pregnantqueens because it may cause teratogenic effect.
Griseofulvin
You are planning on treating a dermatophyte infection in a dog using anorally absorbed drug. Two drugs commonlyused for this type of therapy are (twoanswers) :
Grisofulvin & Ketoconazole
blindness in the dog due toacute uveitis is commonly associated with acute infections with this dimorphicfungus
Blastomyces dermatitidis
a capsule and melanin arelargely responsible for the virulence of this fungi , this yeast is noted for the lack inflammatoryresponse seen in infected tissues when it spreads systemically , you have a cat that likes to hang out where the pigeons hangout – this cat is a good candidate to become infected with this agent
Cryptococcus neoformans
Fungi such as Histoplasma capsulatum produce “granulomatousdisease” syndromes in the dog. The primary difference between thisgranulomatous response and other types of inflammatory responses seen withinfectious agents is that the granulomatous response:
is characterized by mononuclear type phagocyticcells
These 3 dimorphic fungi cause systemic disseminated disease in dogs.
Histoplasmacapsulatum, Coccidiodes immitis, Blastomyces dermatidis
Clinically, chronic disseminated blastomycosis \ histoplasmosis \ coccidioidomycosis in the dog is often characterized by:
bone infections - Blastomycosisand Coccidioidomycosis
intestinal infections - Histoplasmosis
All of the fungi listed below can be described as “dimorphicfungi” except :
Cryptococcusneoformans
What are the usual species that develop clinical disease with thesystemic fungi?
humans & dogs
this dimorphic fungi has apropensity to localize in the digestive tract after systemic spread , the term “tuberculated macroconidia” isalways used in reference to this agent , mosthumans in Missouri have had a mild infection with this dimorphic fungus and aresensitive to the antigens on the skin test , largenumbers of spores from this fungus are in bat caves
Histoplasma capsulatum
The term “tuberculated macroconidia” is usedin reference to this agent.
Histoplasma capsulatum
The life form of Histoplasma capsulatum in tissue can best bedescribed as:
small (3.5 microns) buddingyeasts
Histoplasma capsulatum in the animal bodyis:
an obligateintracellular parasite
What is the ecological niche where Histoplasma capsulatum is located?
Soil Saprophyte
M ost humans in Missouri have had a mildinfection with this dimorphic fungus and are sensitive to the antigens on theskin test.
Histoplasma capsulatum
What host species are most commonly affected with clinical disease to Histoplasma capsulatum?
Humans, Dogs & Cats
Missouri is noted as a center of the endemic area forHistoplasmosis. The majority of dogsexposed to the causative agent:
develop acutepulmonary disease
Animal : 2 year old boxer inMissouri (dog has not been out of Missouri)
- Symptoms : Animal chronically losing weight. Chronic cough present. Auscultation indicates pneumonia is present
- Laboratory : Radiographs indicate a diffuse interstitialpattern and hilar lymphadenopathy typical of fungal caused pneumonia
- Histopath : Intracellular yeast cells were observed
Histoplasma capsulatum
This dimorphic fungus has a propensity tolocalize in the digestive tract after systemic spread .
Histoplasma capsulatum
Clinically, chronic disseminated histoplasmosis in the canine is oftencharacterized by:
intestinal infections
These two drugs from different families wouldbe most useful in treatment of an acute pneumonia caused by Histoplasmacapsulatum in the dog.
Amphotericin B & Ketoconazole
According to most authoritative sources, Histoplasmosis in the dog inregards to the possibility of transfer of the disease from infected dogs tohumans:
is of little zoonoticsignificance
known for itsnephrotoxicity is used to treat fungal infectionsmust be given be slowintravenous injection
Amphotericin B
used to treat fungal infections of the skin but should not be used for treatment of pregnant queens because of the potential for teratogenic effects
Griseofulvin
Many of the drugs used to treat fungal infections affect ergosterol insome way. What part of the fungal cellstructure would then be affected? Whichdrugs affect egosterol?
Cytoplasmicmembrane - Amphotericin B, Terbinatine,Azoles
What is the site of activity of Griseofulvin in fungi?
Inhibits nucleic acid synthesis & cell mitosis
What is the major toxicity problem of Amphotericin B in dogs?
This drug, which is given by intravenous injection in the dog for fungal infections, is almost always associated with serious side effects including nephrotoxicity and anemia.
The most important side effect of Griseofulvin in the cat / AmphotericinB in the dog / Ketoconazole in the cat involves toxic effects on these organs:
kidneys - Amphotericin B
liver - Ketoconazole
teratogenic problems - Griseofulvin
Which would be the more toxic drug to cats: Ketoconazole or Itraconazole ? What organ is usuallyaffected in Ketoconazole toxicity in the cat?
Ketoconazole - Liver
blindness in the dog due toacute uveitis is commonly associated with acute infections with this dimorphicfungus
Blastomyces dermatitidis
A very large single budding yeast is the characteristic tissue form ofthis systemic fungus.
Blastomyces dermatitidis
What type of environmental habitat is associated with development ofBlastomycosis in dogs?
soil
What species are most commonly affected with clinical disease to Blastomyces dermatitidis?
humans & dogs
Clinically, chronic disseminated blastomycosis in the dog is oftencharacterized by (1 or 2 answers):
bone infections & draining skin lesions
Blindness in the dog due to acute uveitis is commonly associated withacute infections with this dimorphic fungus.
Blastomyces dermatitidis
Which of the listed fungi is most likely to cause an acute uveitis (with possible blindness) in affected dogs?
Blastomyces dermatitidis
Animal : 2 year old male Dobermanin Tennessee
- Symptoms and Lesions : Ulcerativelesion of skin and subcutaneous tissue on the right leg. Dog was losing weight. Temperature was 104 o F
- Laboratory : Direct smear (lacto‑phenol cotton blue),large single budding yeast (with “collar”)
Blastomyces dermatitidis
A family dog has been diagnosed as having Blastomycesdermatitidis pneumonia. Knowing the public health significance of thisfungus you:
tell the family that the disease is probably not contagious to humansand recommend treatment if prognosis indicates treatment would be successful.
systemic disease with thisdimorphic fungus is characterized by bone lesions at the epiphyseal junction , spherule is the characteristic tissue from , natural habitat these pathogenic fungi are associated with rodentburrows in the southwestern deserts
Coccidioides immitis
The spherule is the characteristic tissue form of this fungal species.
Coccidioides immitis
The type of spores that are produced by Coccidioidesimmitis in nature
alternating arthrospores
What is the life form of Coccidioidesimmitis in tissue?
spherules
In their natural habitat these pathogenic fungi are associated withrodent burrows in the Southwestern deserts.
Coccidiodes immitis
T/F: Ecologically, this systemic fungus is only found in the desert southwestin the United States.
False - also found in Central and South America
What species are most commonly affected with clinical disease to Coccidioides immitis?
humans & dogs
What type of environmental habitat is associated with development of Coccidioidomycosis in dogs?
Semi-arid “Lower sonoranlife zone“
Systemic disease with this dimorphic fungus ischaracterized by bone lesions at the epiphyseal junction.
Coccidioides immitis
Clinically, chronic disseminated Coccidioidomycosis in the dog is often characterized by (1 or 2 answers):
bone infections & draining skin lesions
According to most authoritative sources, Coccidioidomycosis in the dog in regards to the possibility oftransfer of the disease from infected dogs to humans:
is of little zoonotic significance
a capsule and melanin arelargely responsible for the virulence of this fungi , this yeast is noted for the lack inflammatoryresponse seen in infected tissues when it spreads systemically , you have a cat that likes to hang out where the pigeons hangout – this cat is a good candidate to become infected with this agent
Cryptococcus neoformans
What 2 species of Cryptococcus are capsulated and thus most likely to be associated with disease conditions?
Cryptococcus neoformans & Cryptococcus gattii
A description of these two pathogens would be: capsulated single-budding monomorphic yeasts.
Cryptococcus neoformans & Cryptococcus gattii
What type of spores are produced by Cryptococcusneoformans?
blastospores
What are the 2 major virulence factors of Cryptococcus neoformans?
Capsule - antiphagocytic
Melanin - impairsantibody formation
What is the major ecological niche of Cryptococcus neoformans?
Pigeon excreta (Urban centers)
You have a cat that likes to hang out wherethe pigeons hang out. This cat is a goodcandidate to become infected with this agent.
Cryptococcus neoformans
What are the two major hosts affected by disease with Cryptococcus neoformans?
humans & cats
What species of animal is mostcommonly affected with clinical disease to Cryptococcus neoformans?
cats
This yeast is noted for the lack of inflammatory response seen ininfected tissue when it spreads systemically.
Cryptococcusneoformans
One of the major manifestations of the disease”Cryptococcosis” as seen in its usual animal host often issymptomatically diagnosed as:
nasal granuloma
Animal : 4 year old Siamese cat inSt. Louis. Lesion: Nasal granuloma that was surgicallyremoved.
Laboratory : Histopath, single budding capsulated yeastobserved with PAS stain
Cryptococcusneoformes
What is the major localization of infection in disseminated Cryptococcosis in cats ?
Nasal Granuloma
A 5 year old domestic shorthair cat in Chicago showed signs of centralnervous system disease (the symptomatic diagnosis was meningitis). On a direct smear of cerebral spinal fluid,single budding capsulated yeasts were observed with PAS stain.
Cryptococcus
The tissue reaction seen in Cryptococcus meningitis of the catcan best be described as:
a diffuse granulomatous reaction with fewinflammatory cells.
The use of India Ink is a valuable tool in diagnosing infection withthis fungal agent.
capsule
What is the prognosis for resolution of disease in a cat with a nasalgranuloma? In a cat with meningitis?
Nasal - good prognosis
Meningitis - poor prognosis
What drug in the azole family is commonly used in treatment of cats withCryptococcal meningitis?
Fluconazole
What species of monomorphic yeast has recently appeared as a seriouspathogen in the Pacific Northwest (Canada and United States)?
Cryptococcus gattii
What is the unique ecological niche of Cryptococcus gattii ?
Trees - Douglas fir, Red Cedar, Oak & Maple
thismonomorphic yeast is known to cause a greasy seborrhea with thickened skin
Malassezia pachydermatis
the term “cigar body” is usedas a descriptive term for the tissue phase of this agent
Sporothrix schenckii
These two yeasts are commonly isolated from the canine ear canal asnormal flora and in disease.
Malassezia pachydermatis and Candida albicans
New name for the fungus originally called Pityrosporum canis
Malassezia pachydermatis
This yeast is isolated from the ear canal andskin infections in dogs.
Malassezia pachydermatis
What is the usual ecological niche of Malasseziapachydermatis?
skin
How would you describe Malasseziapachydermatis?
Monomorphic, yeast , non-capsulated
This monomorphic yeast is known to cause achronic moist dermatitis with a musty odor in dogs.
Malassezia pachydermatis
This monomorphic yeast is known to cause a g reasy seborrhea with thickened skin.
Malassezia pachydermatis
This drug is probable drug of choice for systemictreatment of serious Malassezia pachydermatis infections of the skin of dogs.
Ketoconazole & Iatraconazole
The term “cigar body” is used as a descriptiveterm for the tissue phase of this agent.
Sporotrichum scheneckii
The disease Sporotrichosis as seen in thehorse is often symptomatically diagnosed as:
lymphangitis
The disease “Sporotrichosis” is most commonly seen in which of the listed animals?
horses
This agent causes an ulcerative lymphangitis in horses.
Sporotrichumscheneckii
What is the usual method by which animals are infected with Sporothrixschenckii?
implantation
What is the usual ecological niche of Sporothrix schenckii?
rotting materials
Describe the parasitic tissue phase of Sporothrixschenckii?
“cigar body”
This agent produces unique “flowerettes” in themycelial phase of growth.
Sporotrichum scheneckii
What is drug treatment of choice for Sporotrichosis in the horse?
iodides
Yeasty Beasties & Other Mycotic Issues : Who are the “Yeasty Beasties”?
Malasieziapachydermatis
What is the most common underlying disease predisposing to Malassezia dermatitis?
Modified host defensemechanisms
What is the best means to detect Malassezia in lesions?
cytology
What are the systemic antimicrobials recommended for treatment of Malassezia dermatitis?
Ketoconazole, Iatraconazole, Fluconazole,Terbinatime.
genusof fungi is one of the genera commonly implicated in mycotoxicosis , most common fungal species isolated from guttural pouchmycosis in the horse
Aspergillus
most probable exudate in anasal discharge in a dog presenting with a nasal discharge
Aspergillus flavus
mostcommonly cultured cause of a dog presenting with a disseminated fungal disease
Aspergillus terreus
disease caused by thisagent could properly be called zygomycosis
Mucor sp.
cause of pythiosis in dogs
Pythium insidiosum
spherule is the characteristictissue form of this fungi
Rhinosporidium seeberi
What must be demonstrated Histopathologically before a definitivediagnosis can be made of an infection with the monomorphic mycelial fungi?
Demonstration of hyphal elements invading thetissue
This monomorphic mycelial fungus causes serious problems in captive birdpopulations under stress.
Aspergillus fumigates
The usual cause of Canine DisseminatedAspergillosis.
Aspergillus terreus
This monomorphic mycelial fungus is the most common cause of mycotic abortionin cattle.
Aspergillis fumigatus
This is the most common agent isolated fromguttural pouch mycosis in the horse.
Aspergillus
Disease caused by this agent could properly becalled Zygomycosis.
Mucor sp.
This agent is the cause of pythiosis in dogs.
Pythium insidiosum
This agent, a common cause of the diseasesoften labeled “phycomycosis” is actually not a fungus but mayactually belong in the kingdom ___?___.
Protista
What type of disease is associated with Pythium insidiosum?
Pythiosis
What is the ecological niche associated with Pythium insidiosum?
Stagnant water
What is the infective stage of Pythiuminsidiosum to animals?
Motile zoospores
How effective are antifungal drugs in the treatment of pythiosis?
not very
What is the ecological niche associated with Rhinosporidium seeberi?
stagnant water
The tissue phase of Rhinosporidium seeberi consists of:
spherules
The spherule is the characteristic tissue formof these two fungal species.
Rhinosporidium seeberi and Coccidioides immitis
This agent causes large nasal polyps in horses.
Rhinosporidiumseeberi
Newdiagnostic tests for Pythiosis: Whatdiagnostic tests are available for diagnosis of Pythiosis?
Sensitive & specificserologic, PCR, immunochemical tools
Equine Pythiosis: What was the successful treatment regimen forthe Pythiosis infection in the horse in this article?
Surgical and antifungal drugs
Pythiosis in Dogs: What does the author say about the incidenceof Pythiosis in dogs in the United States?
Not known but thenumber of cases have risen over 5 years.
What is the key element in having a successful outcome withimmunotherapy in dogs (and horses)?
Early diagnosis.
Horses>90% and Canine >50%.
