Exam I Study Guide Flashcards
Are fungi classified as eukaryotic or prokaryotic?
eukaryotic
What is the structural element that comprises a fungus?
hyphae
Which class of fungi has non-septate mycelium?
zygomycetes
Why are certain fungi classified as “Fungi Imperfecti”?
They do not exhibit sexual reproduction, sexual phase is undiscovered; Deuteromycetes
How does the function of reproductive mycelia differ from that of vegetative mycelia?
Vegetative grows below the surface of the medium and anchor the fungus; digestive enzymes
Reproductive projects above the surface of the medium where reproductive structures are located-spores
To which class do most pathogenic fungi belong?
Deuteromycetes
What term best describes the nutritional characteristics of fungi?
Heterotrophic/Saprotrophic
Are fungi aerobi or anaerobic?
aerobic
What is the best medium for the primary isolation of fungi?
Sabourad’s (w/ dextrose)
What is the purpose of corn meal agar?
nutritionally deprives the organism so it will sporlate
How long should routine fungal cultures be held before being discarded?
4 weeks
What three things does the counting medium lactophenol cotton blue do?
lactic acid-preserves fungal structures
phenol-reduces contamination of the environment
cotton blue-stains hyaline fungal structures
When a systemic mycosis has spread to various organs, what term is used to describe it?
disseminated
systemic
What organism is best described as a thick-walled yeast cell with buds attached by a broad base?
Blastomyces dermatitidis
Which systemic fungus is always a yeast?
Cryptococcus
How is histoplasmosis acquired?
inhalation of spores from free-living fungus; infect reticuloendothelial system(RES)
Name five species of dimorphic(diphasic) fungi.
Blastomyces Histoplasma Paracoccidiodes Sporotrichosis Coccidiodes
Which systemic fungus produces thick-walled yeast cells with multiple buds in tissue?
Paracoccidiodes braziliensis
Which fungus can be observed as a non-budding, thick-walled spherule containing endospores in a direct smear from the body?
Coccidiodes imitis
Which fungus produces spiny, tuberculate macroconidia when cultured, but in the body can be seen as intracellular, yeast-like cells with a large vacuole in the cells of the RE system?
Histoplasma capsulatum
Cryptococcosis is usually seen as a disease of which body system?
pulmonary
Which systemic fungus is most fastidious(difficult to grow) in the lab?
Histoplasma
What systemic fungus causes San Jaquian Valley Fever?
Coccidiodes
Which systemic fungus causes South American blastomyces?
Paracoccidiodes
Which stain is best to use to demonstrate Cyrptococcus neoformans in CSF?
India Ink
Which systemic fungus is endemic in Piedmont, NC and can produce a primary pulmonary infection or a primary skin infection which resembles ringworm?
Blastomyces
Which systemic fungus produces chains of arthrospores and can be confused with the saprophytic fungus Geotrichum candidum?
Coccidiodes imitis
What is the macroscopic appearance of Sporothrix scheneckii at 37degrees?
yeast phase: soft, smooth, white to cream color, tan colonies
Phialophora
Fonsecaea
Cladosporium
Dematiaceous fungi
Which subcutaneous infection produces yeast-like brown cells in clusters in the body?
Chromomycosis
What is the most common cause of maduromycosis?
What color are the granules that are frequently found in the pus?
Petriellidum boydii
yellow to whitish
What fungus produces tear-shaped conidia arranged in rosettes at 25 degrees and yeast cells at 37 degress, and cause a disease common among gardeners know as “rose fever”?
Sporothrix scheneckii
Cladosporium carrionii
Phialophora verucosa
Fonsecaea pedrosoi
Fonsecaeo compacta
Cause Chromomycosis
Which organisms can cause mycetomas(fungal tumors)?
Allechria Boydii
Madurella mycetomatis
Petrielldieum
An organism which produces brown, branching septate hyphae would be classified as what type of fungus?
Dematiaceous fungi
Fungus infecting the dermis, keratinized areas of the body such as hair, skin and nails
Dermatophytes
What device can be used as an aid to select hairs infected with ringworm?
Wood’s Light
UV light
What type of hair infection is characterized by empty areas or tunnels where the hyphae have degenerated visible throughout the entire length of the hair?
Favic
What combination of fungal media would be best to use to culture the dermatophytes?
SabsC and Myosel (acid pH)
Which three genera of fungi all cause true ringworm of the skin?
Microsporum
Trichophyton
Epidermophyton
What fungus appears velvety white on the front and mahogany on the reverse and will NOT grow on sterile unfortified rice grains?
Microsporum audouinii
What fungus is the most common cause of ringworm in dogs and cats and is characterized by a canary yellow reverse and spiny, spindle-shaped macroconidia?
Microsporum canis
What fungus is most frequently isolated from human ringworm infections and has a deep red reverse pigmentation?
Trichophyton rubrum
What structures are frequently observed in Trichophyton cultures?
spiraled/coiled hyphae
nodular bodies
racket hyphae
As a rule, which dermatophyte does NOT infect nails?
Microsporum audouinii
Which dermatophyte is the most common cause of epidemic scalp ringworm in American school children?
Trichophyton tonsurans
What fungus cause tinea versicolor?
Malassezia furfur
Pityrosporon furfur
What fungus is the most common cause of tinea cruris?
Epidermatophyton floccosum
What term is used to refer to ringworm of the skin?
tinea corporis
What dermatophyte gives a positive in vitro hair test?
Trichophyton mentagrophytes
Which dermatophyte produces sterile, antler-like hyphae referred to as favic chandliers and causes severe type of ringworm of the scalp called favus?
Trichophyton schoenleinii
Which dermatophyte does not invade the hair and produces oval, smooth walled club-shaped macroconidia and NO microconidia?
Epidermophyton floccosum
Which dermatophyte is the most common cause of ringworm of cattle and requires both inositol and thiamine to grow well?
Trichophyton verrucosum
How is Candida albicans identified?
germ tube test
confirmation of chlamydospore production on corn meal agar
Which fungus is the most common and troublesome laboratory contaminant and is the most pathogenic of the opportunistic fungi?
Aspergillis
If an autopsy revealed systemic infection by fungus with broad, branching non-septate hyphae, which species of fungus could be a likely cause of death?
Mucor/rhizopus
Which fungus commonly produces oval budding cells with pseudohyphae and will produce chlamydospores on cornmeal agar?
Candida albicans
Brown gritty deposits in a sputum specimen are indicative of what genus?
Aspergillis
What clinical conditions can be caused by Candida albicans?
thrush, foamy diarrhea, monilia, type of pneumonia, endocarditis, mycotic keratitis, endopthalmitis
Which species of opportunistic fungi can be causative agents of eye infections?
Altenaria
Curvularia
Fusarium
Which species of Rickettsia causes epidemic typhus? Scrub typhus? Q fever? Rickettsial pox? RMSF?
Prowazekii R. tsutsugamuschi coxiella burnetti R. akari R. ricketssi
How do Rickettsia and Chlamydia differ?
Chlamydia is smaller, they are not dependent on arthropod vectors for their transmission; are more spherical
What clinical conditions can be caused by Chlamydia trachomatis?
inclusion conjungtivitis
trachcoma
NGU
How is psittacosis spread to humans?
birds; aerosol inhalation
How are Rickettsial infections diagnosed in the laboratory?
Giemsa stain
Weil-Felix reaction
What causes the rash that is frequently observed in Rickettsial infections?
invasion of endothelial cells of blood vessels
What are the characteristics of viruses?
obligateintracellular parasites
composed of protein and nucleic acid; RNA or DNA not both
seen with electron microscope
doesn’t respond to antibiotics
What term is used to refer to the viral nucleic acid core together with its protein coat?
nucleocapsid
What is the order of events in the process of viral infection?
adsorption penetration viropexis(engulfed) replication assembly release
What is interferon?
*prevents viral replication
protein produced by cells that are already infected with a virus that protects adjacent, non-infected cells
Which virus produces an acute respiratory infection and is commonly found in increased incidence in military camps?
Adenoviruses
Which virus is the causative agent of the common cold?
Rhinovirus
Which type of virus is referred to as “virus in search of a disease”?
ECHO
enteric cytopathogenic human orpahn
Negri bodies are characteristics of which virus?
Rhapdovirus-rabies
Which virus causes chicken pox?
Varicella-Zoster
With what clinical conditions is EBV associated?
infectious mono
Burkitt’s lymphoma
Which virus produces large, red intranuclear inclusions?
CMV-cytomegalovirus
How is Hepatitis A transmitted?
fecal-oral route
Herpes-Zoster(shingles) occurs in patients who have a history of what other viral infection?
Varicella-Zoster -chicken pox
What are the characteristics of Hep B?
serum hep - transmitted by blood
blood contact by IV users, drug addicts
How many serotypes of polio virus are there?
3
Which vaccines have been developed against polio?
Salk
Sabin
Which virus has been associated with cancer of the cervix and causes genital lesions in humans?
HSV-2
Which fungus is most frequently isolated in the clinical laboratory?
Candida albicans
The _____ test is a serological test used in the identification of Rickettsia that employs three antigens of the bacteria ____ that cross-react with rickettsial antigens.
Weil-Felix reaction
Proteus vulgaris
What virus is associateed with severe congenital abnormalities in the fetus if the mother becomes infected during her first trimester?
Rubella- german measles
What “emerging” viral pathogen causes an upper respiratory tract infection in infants and young children?
RSV - respiratory syncytial virus
To what group of viruses does HIV belong?
These viruses have no DNA and possess what enzyme that is capable of converting RNA to DNA?
Retrovirus
reverse transcriptase
Name two disease processes that are common in HIV patients that are rarely seen in “normal” individuals.
Cryptosporidium
CMV
toxiplasmosis
prowazekii (epidemic typhus) vector
body louse
tsutsugamuschi (Scrub typhus) vector
larvae mite
akari (rickettsial pox) vector
mite
coxiella burnetti (Q fever) vector
no vector
rickettsi (RMSF) vector
wood tick
