Micro Unit 5 Review

Match the organism with its characteristics. 1 - Polysaccharide capsule 2 - "Spaghetti and meatball" morphologic appearance 3 - White piedra 4 - Creamy, white patches A. C. albicans B. C. neoformans C. Trichosporon spp. D. M. furfur

1 - B 2 - D 3 - C 4 - A

Cryptococcus neoformans is widely distributed in nature, and aerosolization is a prerequisite to most infections. This organism is most often associated with exposure to: contaminated soil. pigeon excreta. contaminated food. rat excreta.

pigeon excreta.

A hair perforation test is performed using Trichophyton mentagrophytes and T. rubrum. The expected results are: positive for both organisms. positive for T. rubrum and negative for T. mentagrophytes. positive for T. mentagrophytes and negative for T. rubrum. negative for both organisms.

positive for T. mentagrophytes and negative for T. rubrum.

Match the antifungal agent with its mode of action. 1 - Is a glucan synthesis inhibitor 2 - Alters membrane permeability 3 - Inhibits protein synthesis 4 - Binds microtubular proteins 5 - Interferes with ergosterol synthesis A. Griseofulvin B. Amphotericin B C. 5-Fluorocytosine D. Echinocandin E. Azole

1. D 2. B 3. C 4. A 5. E

Match each disease state with the organism that causes it. 1 - Sinusitis 2 - White grain mycetoma 3 - Tinea nigra 4 - Black piedra 5 - Black-grain mycetoma A. E. jeanselmei B. P. boydii C. Piedraia hortae D. Alternaria E. H. werneckii

1. D 2. B 3. E 4. C 5. A

The agency that provides documents and sets standards for antifungal susceptibility testing is the: National Accrediting Agency for Clinical Library Sciences (NAACLS). Association of Specialized and Cooperative Library Agencies (ASCLS). College of American Pathologists (CAP). Clinical Laboratory Standards Institute (CLSI).

Clinical Laboratory Standards Institute (CLSI)

Trichophyton schoenleinii causes a condition that is characterized by the formation of yellowish cup-shaped crusts or scutulae, considerable scarring of the scalp, and sometimes permanent alopecia. This organism is usually recovered in _____ days. 5 to 7 14 21 30

30

The optimal temperature and length of time to incubate a sample suspected of containing a dermatophyte is _____°C for _____ days. 25; 10 25; 14 30; 7 30; 21

30; 21

Which rapidly growing Aspergillus spp. (2 to 6 days) best describes a mold that produces a fluffy-to-granular, white-to-blue green colony? A. niger A. flavus A. fumigatus A. terreus

A. fumigatus

Microscopically, this fungus appears barrel shaped with thick walls, which best describes which type of conidia? Macroconidia Chlamydoconidia Arthroconidia Blastoconidia

Arthroconidia

Which phylum exhibits both a teleomorph and an anamorph form? Ascomycota Basidiomycota Deuteromycota Zygomycota

Ascomycota

A 59-year-old patient with cancer who was receiving high doses of chemotherapy developed a secondary lung infection that was identified as a fungus. The organism disseminated, which ultimately was fatal to the patient. The organism isolated from sputum exhibited septate hyphae that were dichotomous. The organism is most likely which of the following? Candida Cryptococcus Aspergillus Zygomycetes

Aspergillus

A pulmonary fungus ball and external otomycosis and onychomycosis are all infections caused by which genera? Fusarium Penicillium Paecilomyces Aspergillus

Aspergillus

An example of a dimorphic fungus is: Candida albicans. Coccidioides immitis. Cryptococcus neoformans. Aspergillus fumigatus

Coccidioides immitis.

Blood cultures are drawn on a patient suspected of having a fungemia. Positive cultures reveal the presence of chlamydoconidia on cornmeal agar. In addition, the yeast is germ tube positive. The most likely identification of the fungal agent is: C. glabrata. C. tropicalis. C. neoformans. C. albicans.

C. albicans.

If cornmeal agar is set up and chlamydoconidia are produced, the organism is most likely: C. krusei. C. glabrata. C. albicans. C. tropicalis.

C. albicans.

A capsule and phenoloxidase melanin synthesis are virulence factors contributing to the pathogenicity of which of the following organisms? Aspergillus spp. P. brasiliensis B. dermatitidis C. neoformans

C. neoformans

A patient with acquired immunodeficiency syndrome (AIDS) notices skin lesions on his back that have begun to ulcerate. Upon physical examination, his physician also notices hepatomegaly that is most likely caused by hepatitis. The physician prescribes antifungal therapy to prevent the dissemination of which of the following yeasts? C. albicans C. neoformans C. glabrata C. tropicalis

C. neoformans

Determining urease activity and growth on niger seed agar is helpful in determining which type of yeast? C. albicans Trichosporon C. neoformans M. furfur

C. neoformans

A patient with leukemia is diagnosed with a Candida infection after receiving several doses of chemotherapy. The most likely yeast causing the infection is: C. albicans. C. parapsilosis. C. tropicalis. Candidametapsilosis.

C. tropicalis.

Which stain requires the use of a fluorescent microscope? Calcofluor white India ink Potassium hydroxide Masson-Fontana

Calcofluor white

The most commonly isolated yeast in clinical specimens is: Candida albicans. Candida tropicalis. Candida dubliniensis. Candida krusei.

Candida albicans.

An agricultural worker is punctured by a tool used in the field. An infection, characterized by the development of a papule that is similar to a cauliflower appearance, develops. The worker is most likely suffering from which type of infection? Mycetoma Chromoblastomycosis Tinea nigra Black piedra

Chromoblastomycosis

The mode of transmission for most of the dimorphic fungi is: inoculation. inhalation. arthropod. blood.

inhalation.

Match the morphologic features with the dimorphic fungus. 1 - Cigar-shaped yeast cells 2 - Nonbudding, thick-walled spherule 3 - Budding yeast resembling a "mariner's wheel" 4 - Yeastlike cells with internal cross walls 5 - Single bud connected to the parent cell by broad base 6 - Small, round-to-oval yeast cells; 2 to 5 µm in diameter A. Talaromyces marneffei B. Blastomyces dermatitidis C. Coccidioides immitis D. Paracoccidioides brasiliensis E. H. capsulatum F. Sporothrix schenckii

1. F 2. C 3. D 4. A 5. B 6. E

Match the microscopic characteristics with their organism. 1 - Conidiophores are bent at the locations where conidia are attached; conidia are sympodially arranged and are oblong to fusoid in shape. 2 - Feltlike, filamentous colonies produce dematiaceous hyphae and conidiophores that are cylindrical and have a tapered tip. 3 - This fundus exhibits cup- or flask-shaped collarette. 4 - Conidia are usually single celled and exhibit prominent attachment scars (disjunctors). 5 - Conidial heads with a sympodial arrangement of conidia exhibit primary conidia giving rise to secondary conidia. 6 - Conidia are arranged sympodially, golden brown, multicelled, and curved with a central swollen cell. 7 - Conidiophores bear a chain of large brown conidia, resembling a drumstick, and contain both horizontal and longitudinal septa. A. Cladophialophora B. Alternaria C. Exophiala D. Fonsecaea E. Phialophora F. Bipolaris G. Culvaria

1. F 2. C 3. E 4. A 5. D 6. G 7. B

Which two assays should be used together for detecting antibodies toward B. dermatitidis, H. capsulatum, and C. immitis? Enzyme-linked immunosorbent assay (ELISA) and direct fluorescent antibody (DFA) Complement fixation and immunodiffusion Indirect fluorescent antibody (IFA) and Western blot Enzyme immunoassay (EIA) and latex agglutination

Complement fixation and immunodiffusion

Which form is considered diagnostic in the life cycle of Pneumocystis jirovecii? Bradyzoite Trophozoite Sporocyte Cyst

Cyst

In patients who do not have HIV, which underlying condition is considered a risk factor for acquiring PCP? Malaria Cystic fibrosis Cytomegalovirus Myasthenia gravis

Cystic fibrosis

A fungus is recovered from a nail scrapping. Microscopic examination reveals numerous smooth, thin-walled, club-shaped, multiseptate macroconidia; however, microconidia are absent. The organism can be identified as: Microsporum canis. E. floccosum. T. rubrum. M. gypseum.

E. floccosum.

Which genus is involved in infections of the skin and nails only? Microsporum Epidermophyton Trichophyton Scopulariopsis

Epidermophyton

An example of a thermally monomorphic mold is: P. marneffei. S. schenckii. Epidermophyton. H. capsulatum.

Epidermophyton.

Colonies are isolated 4 days after incubation from a skin infection that disseminated in a burn victim. A fungal infection is suspected. Which of the following is a possible organism that may be identified? Epidermophyton floccosum Fusarium spp. Cladosporium spp. Microsporum audouinii

Fusarium spp.

A patient who is positive for the human immunodeficiency virus (HIV) is diagnosed with a Cryptococcus neoformans infection. The attending resident prescribed Griseofulvin; however, the patient's condition did not seem to improve. Which one of the following statements explains this discrepancy? - The dose should be increased to penetrate the blood-brain barrier. - Nystatin, which would have been more effective, should have been prescribed. - Griseofulvin is not effective against C. neoformans; therefore the therapy should be changed. - Potassium iodide is the therapy of choice, not griseofulvin.

Griseofulvin is not effective against C. neoformans; therefore the therapy should be changed.

The slow-growing organism Trichophyton rubrum produces a flat or heaped-up colony, generally white to reddish with a cottony or velvety surface. The cherry-red color is best observed on the reverse side of the colony. This organism is capable of infecting which of the following? Hair and nails Skin and nails Hair and skin Hair, skin, and nails

Hair, skin, and nails

Which therapy has decreased the incident of pneumocystis infection in patients with human immunodeficiency virus or acquired immunodeficiency syndrome (HIV/AIDS)? Metronidazole Trimethoprim-sulfamethoxazole combination Aminoglycosides with fluconazole Highly active antiretroviral therapy (HAART)

Highly active antiretroviral therapy (HAART)

All mold cultures and clinical samples should always be handled in a Class _____ level biosafety cabinet. I II III IV

II

Encapsulated yeast is identified in the cerebrospinal fluid (CSF) of a patient with AIDS. The most likely stain or reagent used to identify this organism is: potassium hydroxide (KOH). calcofluor white. lactophenol cotton blue. India ink.

India ink.

Fungal infections are generally acquired via which route? Person to person Nosocomial Vector Inhalation of spores

Inhalation of spores

Blood cultures are collected from a 36-year-old patient suspected of having a disseminated fungal infection. History reveals that she was exposed to bird droppings and may have inhaled the conidia. What is the best blood culture system to use to ensure optimal recovery of this pathogen? BACTEC BacT/ALERT ESP system Isolator system

Isolator system

Tinea versicolor is a skin infection characterized by superficial brownish scaly areas most often on the trunk, arms, or shoulders. Which type of replacement therapy places patients at risk for developing this type of skin infection? Hormone Lipid Saccharide Gene

Lipid

Agar medium overlaid with olive oil will enhance the growth of which organism? Malassezia Candida Trichosporon Cryptococcus

Malassezia

Which yeast identification system uses chromogenic substrates to assess specific enzyme activity usually detected within 4 hours? Vitek MicroScan API-20C AUX Uni-Yeast-Tek

MicroScan

The Reference Method for Broth Dilution Antifungal Susceptibility Testing of Filamentous Fungi; Approved Standard (M38-A2) describes the guidelines for antifungal susceptibility testing for molds. The suspension must be standardized with a spectrophotometer. Susceptibility testing is determined by which method? Disk diffusion Microdilution Broth dilution Immunodiffusion

Microdilution

Which dermatophyte usually fluoresces yellow-green under a Wood's lamp? Microsporum gypseum Trichophyton verrucosum Microsporum audouinii Epidermophyton floccosum

Microsporum audouinii

Which fungal media is ideal for the recovery of organisms such as Microsporum and Trichophyton? Cornmeal agar with Tween 80 Niger seed agar Cottonseed conversion agar Mycosel agar

Mycosel agar

Macroscopic examination of granules from lesions of mycetoma reveals them to be white to yellow and 0.2 to 2 mm in diameter. Microscopically, the granules consist of loosely arranged, intertwined septate hyaline hyphae cemented together. Which organism can cause a mycetoma infection? Fonsecaea spp. E. dermatitidis Cladosporium spp. P. boydii

P. boydii

An organism was isolated after growing 26 days. Colonial morphologic appearance revealed heaped, wrinkled, moist, and yeastlike colonies. As the culture aged, colonies became covered with short aerial mycelium that turned from tan to brown. This organism is most likely: Blastomyces dermatitidis. Coccidioides immitis. Histoplasma capsulatum. P. brasiliensis.

P. brasiliensis.

Which organism produces mostly shades of green or blue-green colonies? Microscopically, hyphae are hyaline and septate and produce brushlike conidiophores. Paecilomyces Acremonium Scopulariopsis Penicillium

Penicillium

Which dematiaceous fungus causes a condition known as chromoblastomycosis? P. boydii Hortaea werneckii Phialophora spp. Exophiala jeanselmei

Phialophora spp.

Mycetoma is a subcutaneous infection that involves the lower extremities but may also occur in any part of the body. Swelling, purplish discoloration, and tumorlike deformities of the subcutaneous tissue are all symptoms associated with mycetoma. Which organism can cause this disease? Bipolaris spp. Exserohilum spp. Pseudallescheria boydii Exophiala dermatitidis

Pseudallescheria boydii

Which type of molecular assay has been developed to identify P. jirovecii? Nucleic acid sequence-based amplification (NASBA) Strand displacement amplification (SDA) Transcription-mediated amplification (TMA) Real-time polymerase chain reaction (PCR)

Real-time polymerase chain reaction (PCR)

A septate hyphae is microscopically observed using lactophenol cotton blue. Which organism can be ruled out as the cause of infection on the basis of this information? Aspergillus Bipolaris Microsporum Rhizopus

Rhizopus

Unbranched sporangiophores with rhizoids that appear opposite the point where the stolon arises at the base of the sporangiophore best describes which zygomycetes? Mucor Rhizopus Lichtheimia Absidia

Rhizopus

A 28-year-old woman was gardening when a rose thorn pricked her finger, which later became infected. A sample is taken of the exudate and sent to the microbiology laboratory. Small, round, cigar-shaped structures are microscopically observed. She is most likely infected with which type of fungi? Malassezia furfur H. capsulatum S. schenckii Fonsecaea pedrosoi

S. schenckii

A 29-year-old patient with acquired immunodeficiency syndrome (AIDS) is suspected of having a C. neoformans infection in the cerebrospinal fluid (CSF). A CSF specimen is collected and set up on cycloheximide agar. In addition, an India ink stain is set up. The India ink stain reveals encapsulated yeast; however, 3 weeks later, the cycloheximide agar is negative. Which one of the following statements explains this discrepancy? - The India ink result is most likely false positive. - The ingredients in the cycloheximide agar most likely inhibited the growth of the organism. - C. neoformans is rarely recovered from CSF; therefore the cycloheximide result is accurate. - The India ink stain is most likely contaminated.

The ingredients in the cycloheximide agar most likely inhibited the growth of the organism.

Urea agar is set up for quality control purposes using two Trichophyton spp.—T. mentagrophytes and T. rubrum. After the appropriate amount of incubation, both organisms are negative. Which one of the following statements explains this discrepancy? The medium is most likely expired. These two Trichophyton spp. are poor choices for quality control. The phenol red indicator is not working because both organisms are positive for urea. No discrepancy is present; both organisms are negative for urease activity.

The medium is most likely expired.

The term used to describe ringworm of the nail is: Tinea cruris. Tinea pedis. Tinea capitis. Tinea unguium.

Tinea unguium.

Which of the following Trichophyton spp. grows slowly (14 to 30 days) and best at 35°C to 37°C? In addition, enriched media with thiamine and inositol enhance its growth. Trichophyton verrucosum Trichophyton tonsurans T. rubrum T. mentagrophytes

Trichophyton verrucosum

A fungal infection found mostly in the tropics and temperate regions is characterized by the development of soft, yellow or pale-brown aggregations around hair shafts in the axillary, facial, genital, and scalp regions. The fungus that would most likely be isolated is: Candida. Malassezia. Cryptococcus. Trichosporon.

Trichosporon

A patient is diagnosed with an invasive Aspergillosis infection. The antifungal therapy that should be administered is: nystatin. griseofulvin. amphotericin B. fluconazole.

amphotericin B.

In general, yeast reproduces asexually by the formation of: ascospores. basidiospores. blastoconidia. arthroconidia.

blastoconidia.

If a fungal colony is described as rugose, then it means that the colony: is furrowed or convoluted. is slightly raised in the center. furrows radiate out from the center. has a smooth surface with no aerial mycelium.

furrows radiate out from the center.

The cell membrane of P. jirovecii contains _______ rather than _______, which differentiates it from other fungi. - sterols; cholesterol - ergosterol; sterols - cholesterol; ergosterol - sitosterol; sterols

cholesterol; ergosterol

A 16-year-old male teenager is diagnosed with a fungal infection of his foot, which he acquired at the gym. This infection would most likely be classified as a(n) _______ mycosis. superficial subcutaneous systemic opportunistic

superficial

A patient with diabetes is experiencing creamy patches on his tongue and mucous membranes. Cultures are performed, and yeast is recovered. His diagnosis is most likely: paronychia. onychomycosis. candidemia. thrush.

thrush.