MLT 240 Exam 1 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”?
lack a sexual phase, or their sexual phase is unknown.
How does the function of reproductive mycelia differ from that of vegetative mycelia
Vegetative mycelia anchors fungus to substrate (grows below), produces digestive enzymes.
Reproductive mycelia project above the surface. Spores are located here.
To which class do most pathogenic Fungi Belong
Deutermoycetes
What term best describes the nutritional characteristics of fungi
saprophytic
saprotrophic
Are Fungi Aerobic or Anaerobic
Aerobic
What is the best single medium for the primary isolation of fungi
Sabouraud’s Dextrose agar (SBA)
What is the purpose of corn meal agar
Organism is nutritionally deprived –> sporulation will occur. Used to observe chlamydospore formation in C. albicans.
How long should routine fungal cultures be held before being discarded
min 4 weeks
what three things does the mounting medium lactophenol cotton blue do
- preserves fungal structure
- reduce contamination of environment
- stain fungal structures
When a systemic mycoses has spread to various organs, what term is used to describe it
disseminated
What organism is best described as a thick-walled yest cell with buds attached by a broad base
Blastomyces dermatiditids
Which systemic fungus is always a yeast ( i.e. is not diphasic)
Cryptococcus neoformans
How is histoplasmosis acquired
inhalation of spores from free-living fungus (growing in environment)
Name the five species of dimorphic (diphasic) fungi
- Blastomyces
- Coccidioides
- Histoplasma
- Paracoccidioides
- Sporotrichosis (NOT CRYPTOCOCCUS)
Which systemic fungus produces thin-walled yeast cells with multiple buds in tissue
Paracoccidioides brazilensis
Which fungus can be observed as a non-budding, think-walled spherule containing endospores in a direct smear from the body
Coccidioides 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 the most fastidious (difficult to grow) in the Lab
Histoplasma capsulatum
What systemic fungus causes San Jacquain Vally Fever
Coccidioides imitis
Which systemic fungus casues South American blastomycoses
Paracoccidioides
Which stain is best used to demonstrate Cryptococcus neoformans in CSF
India ink
Which systemic fungus is endemic in Piedmont NC and can produce a primary pulmonary saporophytic fungus Geotrichum candidum
Blastomyces
Coccidioides
What is the macroscopic appearance of Sporothrix scheneckii at 37 deg.
creamy, yeast colony
List several species of dematiaceous fungi
Phialophora, Fonsecaea, Cladosporium
NOT ASPERGILLIS, PENICILLIUM, OR CANDIDA!
Which subcutaneous infection produces yeast-like brown cells in clusters in the body
Chromomycoses
Divides in all 4 planes; brown, sclerotic bodies
What is the most common cauase of maduromycosis
petriellidum voydii
What color are the granules that are frequently found in the pus of maduromycosis
yellow/whitish
What fungus produces tear-shaped conidia arranged in rosettes art 25 deg and yeast cells when grown at 37 deg and causes a disease common among gardeners which is referred to as “rose fever”
Sporothrix schneckeii
Name several species that can be responsible for chromomycosis
Phialophora, Fonsecaea, Cladosporium
NOT ASPERGILLIS, PENICILLIUM, OR CANDIDA!
Which organism can cause mycetomas (fungal tumors)
Actinomyces
Madurella
* Petriellidieum
An organism which produces brown, branching septate hyphae would be classified as what type of fungus
Dematiaceous
What are Dermatophytes
organism that only invades (non-living) keratinized areas
What device can be used as an aid to select hairs infected with ringworm
Fluorescent light
What typeion of hair infection is characterized by empty areas of 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
Sabouraud’s/mycosel
Which three genera of fungi all cause 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 causes tinea versicolor
Pityrosporon (malassezia) furfur
What fungus is the most common causative agent of tinea cruris?
Epidermophyton
What term is used to refer to ringworm of the skin?
Tinea corpus
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 a severe type of ringworm of the scalp called favus?
Trichophyton schoenleinii
Which dermatophyte does not invade 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
verrucosum
How is Candida albicans identified?
germ tube and chlamydospore agar
Which fungus is the most common and troublesome laboratory contaminant and is the most pathogenic of the opportunistic fungi?
Aspergillus
If an autopsy revealed systemic infection by fungus with broad, branching non-septate hyhae, which species of fungus could be a likely cause of death
Mucor/Rhizopus pg87
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
Aspergillus
What clinical conditions can be caused by Candida albicans
Yeast infection, thrush, etc.
DOES NOT CAUSE RINGWORM
Which species of opportunistic fungi can be causative agents of eye infections?
Altenaria, Curvularia, Fusarium
Which fungus is most frequently isolated in the clinical laboratory?
Candida albicans
Which species of Rickettsia causes epidemic typhus?
- Scrub typhus?
- Q fever?
- Rickettsial pox?
- RMSF?
- Rickettsia prowazekii
(Vector: Body louse) - Rickettsia tsuts- ugamuschi
(Vector: Larval mite) - Coxiella burnetti
(No vector listed) - Rickettsia akari
(Vector: mite) - Rickettsia rickettsi
(Vector: Wood tick)
How do Rickettsia and Chlamydia differ?
Rickettsia = require arthropod vectors
Chlamydia = not dependant on arthropod vectors (transmitted human-to-human)
What clinical conditions can be caused by Chlamydia trachomatis
most common cause of NGU (non-gonococcal urethritis)
most common cause of blindness inclusion conjunctivitis
How is Chlamydia psittacosis spread to humans
aerosol inhalation (same thing)
How are Rickettsial infections diagnosed in the laboratory
Cell culture –> Embryonated eggs
What causes the rash that is frequently observed in Rickettsial infections?
invasion of endothelial cells of blood vessels
What are the characteristics of viruses
have DNA or RNA (not both)
don’t respond to antibiotics
obligate intracellular parasite
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
Absorption (attach to cell), Penetration (viropexis), Replicate, Assemble, Release
What is interferon?
prevents virus replication
Which virus produces an acute respiratory infection and is commonly found in increased incidence in military camps
adenovirus
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 virus (Enteric Cytopathogenic Human Orphan)
Negri bodies are characteristic of which virus
Rhabdovirus
Which virus causes chicken pox
Varicella
With what clinical conditions is Epstein-Barr virus associated
Burkitt’s Lymphoma//Infectious Mononucleosis
transforms lymphocytes to lymphoblastoid cells
Which virus produces large, red intranuclear inclusions
CMV
How is Hepatitis A transmitted
fecal-oral
Herpes-Zoster occurs in patients who have a history of what other viral infection
only in people with a history of chicken pox (varicella)
What are the characteristics of Hepatitis B?
transmitted by blood (serum hepatitis), drug addicts (blood contact)
How many serotypes of polio virus are there?
3
Which vaccines have been developed against polio
Salk vaccine, Sabin vaccine
Which virus has been associated with cancer of the cervix and causes genital lesions in humans
HSV
Type 2
. 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
- Wiel-Felix test
- Proteus vulgaris
What virus is associated with severe congenital abnormalities in the fetus if the mother becomes infected during her first trimester
Rubella (German Measles)
An “emerging pathogen” is one that seems to be on the rise in the last several years. What viral pathogen that causes an upper respiratory tract infection in infants and young children would fall into this category
RSV (respiratory syncytical virus)
To what group of viruses does HIV belong
retrovirus
These viruses have no DNA and possess an enzyme called __________ that
is capable of converting RNA to DNA.
reverse transcriptase
Name two diseases processes that are common in HIV patients that are rarely seen in “normal” individuals
PCP pneumonia toxoplasmosis CMV Kaposi's sarcoma Cryptococciosis MAI tuberculosis
