The Quizzes about Mycology

Mycology Quiz (35 test)

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Question 1

A 65-year-old man was diagnosed with pseudomembranous candidiasis and given a prescription for oral fluconazole. This drug acts by:

A	Binding to membrane ergosterol
B	Incorporation into RNA leading to mistranslation and inhibits DNA synthesis
C	Inhibition of 1,3-β-glucan biosynthesis
D	Inhibition of mitosis
E	Inhibition of squalene 2,3-epoxidase
F	Inhibition P450-dependent sterol demethylase (lanosterol 14α-demethylase)

Question 1 Explanation:

Ergosterol is the major sterol component of the fungal cell membrane while cholesterol is found in mammalian membranes (see table on the next page). The difference is exploited by major antifungal drugs. Azole (imidazole and triazole) class drugs, for example miconazole, fluconazole, itraconazole, and voriconazole, inhibit a cytochrome P450- dependent demethylase (lanosterol 14-α-demethylase), which is in the latter part of the biosynthetic pathway for ergosterol. This pathway is also inhibited at an earlier stage prior to ring formation by allylamines (Terbinafine, naftifine) and tolnaftate. These drugs inhibit squalene-2,3- epoxidase. The inhibition of ergosterol production results in aberrant cell membrane. Polyene class drugs, for example amphotericin B, also exploit ergosterol by binding the sterol leading to channel formation in the membrane that allows leakage of intracellular constituents, for example potassium, and cell death. 5-Fluorocytosine (5FC, flucytosine) is a pyrimidine analog that after conversion to other compounds (5- fluorouracil, 5-fluorodeoxyuridylic acid, and 5-fluorouridine) leads to inhibition of DNA synthesis and RNA miscoding. Echinocandins, for example caspofungin, inhibit the synthesis of 1,3-β-glucan with inhibition of the glucan synthesis enzyme complex. Griseofulvin is thought to inhibit fungal growth by interaction with microtubules resulting in aberrant mitosis and cell division.

Question 2

An AIDS patient with a CD4 count in the range 100 to 50 cells/mm3 complains of headache and neck stiffness and appears disoriented. The possibility of fungal meningitis is considered and tests for the common fungal etiology of meningitis ordered. Tests included direct examination of spinal fluid for the organism and serology. The purpose of the serology test is detection of

A	Antibody to capsular polysaccharide
B	Antibody to cell wall mannoprotein
C	Capsular polysaccharide
D	Cell wall mannoprotein

Question 2 Explanation:

Cryptococcus neoformans is the most common cause of meningitis in AIDS patients. The frequency has declined in areas with robust antiretroviral treatment but can still occur in patients receiving treatment. Patients immunocompromised by other factors, for example maintained on corticosteroids, are also at risk. The organism is inhaled as a desiccated, minimally encapsulated organism or perhaps a basidiospore often after disturbance of soil rich in avian feces such as pigeon guano. The capsule can enlarge upon reaching the lung. Initial pulmonary infection may be asymptomatic and exposure may occur early in life. Symptomatic infection may mimic an influenza-like respiratory infection and resolve spontaneously. Particularly in immunocompromised patients the organism may multiply and disseminate with a predilection for the CNS causing meningoencephalitis. This is often the presenting complaint. The organism grows as encapsulated yeast that, in culture and cerebrospinal fluid, may be highlighted by mounting in India ink. Frequently, detection of capsular polysaccharide antigen is used as a diagnostic tool. There are commercial kits based on latex agglutination or enzyme immunoassay that can be used to detect antigen in serum or cerebrospinal fluid.

Question 3

A 6-year-old African American girl resident of a very large US city presents to a clinic with scaly patches and areas of alopecia on the scalp with hair shafts broken off close to the scalp. The hair did not fluoresce under Wood’s light. If this child has tinea capitis, the most likely etiology is

A	Epidermophyton floccosum
B	Microsporum audouinii
C	Microsporum canis
D	Trichophyton rubrum
E	Trichophyton tonsurans

Question 3 Explanation:

The large majority of fungal cutaneous skin infections are due to dermatophytes. These infections can occur from head to toe and the infections are termed tinea followed by a description of the site (see table on the preceding page). These infections have been called ringworm, a misnomer from the misconception that the cause was a worm. However, that notion is perpetuated in the current terminology as tinea is from the Latin for a gnawing worm. The case is a classic description of tinea capitis that occurs primarily in children before puberty. There are two forms of childhood tinea capitis. One manifestation whose etiology is M. audouinii is sometimes called “gray patch”. Over the past decades, this form has almost disappeared in the USA and been replaced by the second form. The second manifestation of childhood tinea capitis is caused by T. tonsurans and is sometimes called “black dot” because of the “dot” visible within the area of hair loss where a hair shaft broke off leaving a stump. Infections are primarily seen in children 3 to 9 years of age, although some adults may be asymptomatic carriers. If not resolved by treatment, the infection generally resolves with puberty. Among inner-city children the prevalence may be as high as 8%. Both M. audouinii and T. tonsurans are anthropophilic dermatophytes. Microscopic observation of infected hairs shows arthroconidia around the hair shaft (ectothrix) with M. audouinii infection and inside (endothrix) the hair shaft with T. tonsurans infection. Wood’s light is a device that produces ultraviolet light rays. Hairs infected with M. audouinii fluoresce with a yellow-green color under Wood’s light, while T. tonsurans does not. Other species may be more prevalent in other parts of the world as the cause of infection.

Question 4

A 25-year-old male physical therapist trains regularly with the hope of qualifying for the Boston Marathon. He develops itching in interdigital spaces on his left foot. Suspecting tinea pedis he treats the area with an over-the-counter product. The area improves after a course of treatment but two months later reappears and again responded to the same treatment. However, there was reappearance 3 months later. If the selfdiagnosis is correct, the normal habitat of the etiologic agent is most likely described as

A	Anthropophilic
B	Geophilic
C	Zoophilic

Question 4 Explanation:

Tinea pedis (athlete’s foot) is caused by dermatophytes. There are several etiologies of this infection (see table on the preceding page). Dermatophytes are adapted to one of three natural habitats: man (anthropophilic dermatophytes), animals other than man (zoophilic dermatophytes) and soil (geophilic dermatophytes). Infections with anthropophilic dermatophytes tend to be milder, recurrent or chronic, and less likely to completely resolve with topical treatment while those with the other two habitats tend to produce more inflammatory lesions that are not recurrent and respond well to treatment. The patient, in this instance has recurrent episodes, which is usually associated with anthropophilic species of which the most common is Trichophyton rubrum.

Question 5

A patient receiving corticosteroid treatment for lupus developed headache and fever and when she began to display some memory loss she was brought to her physician by her spouse. Considered in the differential diagnosis was cryptococcal meningitis. Which of the following, if found upon examination of cerebrospinal fluid would support that diagnosis?

A	Encapsulated yeast cells
B	Hyphae
C	Intracellular yeast cells
D	Yeast cells with multiple buds
E	Yeast cells with a broad base between mother and daughter cells

Question 5 Explanation:

Cryptococcus neoformans occurs widely in nature, particularly in soil contaminated with bird droppings and is frequently associated with pigeon guano. The organism grows predominately in the yeast form as an encapsulated structure but as a basidiomycete may form hyphae and produce spores. Fungal structures may become dessicated in the environment and small enough to be inhaled into the lungs when material containing the organisms is disturbed. In the lung, the capsule can enlarge and encapsulated yeast cells are found in tissue. Lung infection is often asymptomatic, particularly in a normal host, but can result in pneumonia. Meningitis occurs through dissemination, particularly in immunosuppressed patients. India ink preparations of CSF reveal a budding yeast with a wide, unstained capsule in infected persons. A second species, C. gattii, also causes infections. This species has a more limited geographic distribution and is not associated with bird guano but with vegetation, for example red gum trees. In the United States, the organisms is found on the west coast with recent infections in the Pacific Northwest and infections with this species are reportable in Oregon and Washington. This species tends to infect competent hosts and CNS dissemination is most often seen as a cryptococcoma. The distinctive feature of Cryptococcus spp. yeast cells is the capsule. Other organisms that are found as yeast in host tissue have other distinguishing features such as the multiple budding form of Paracoccidioides brasiliensis, the small intracellular yeast cells of Histoplasma capsulatum and broad-base budding yeast cells of Blastomyces dermatitidis. Aspergillus spp. and agents of mucormycosis are examples of fungi that proliferate as hyphae in tissue.

Question 6

A 35-year-old male, a legal resident in the USA, presented with a complaint of a lesion on the bottom of his foot that was smooth and shiny and somewhat discolored. He reported that it bothered him when wearing some shoes. He reported no chronic diseases or recent illnesses and he was a nonsmoker. Travel history determined that he frequently visited relatives in India. Histopathology of the biopsy specimen showed at 2.4- mm granule surrounded by neutrophils. Tissue staining suggested that the granule contained filaments >1 μm in width. The most likely diagnosis is

A	Actinomycetoma
B	Aspergillosis
C	Chromomycosis
D	Eumycetoma
E	Phaeohyphomycosis

Question 6 Explanation:

Mycetoma is a slowly progressing disease of the subcutaneous tissues that is caused by a variety of fungi (eumycetoma or eumycotic mycetoma) or bacteria (actinomycetoma or actinomycotic mycetoma). The term Madura foot has been used to describe the foot lesion. While mycetoma of either fungal or bacterial etiology is progressive over years, eumycetoma progresses more slowly than actinomycetoma. A localized swollen lesion begins to develop at the site of traumatic inoculation, usually on the hand or foot. Lesions contain suppurative abscesses with sinuses that drain the abscess. Organisms coalesce into granules or grains. As infection advances there is swelling and distortion of the site of infection with sinus tracts waxing and waning. In this case, the infection has not reached the stage of draining sinus tracts. The agents of actinomycetoma also form filaments. A distinction between the two major etiologic groups can be made by observing the width of the filaments. Agents of actinomycetomas have filaments 0.5 to 1 μm in width while fungal hyaphe are greater than 1 μm. There are multiple bacteria or fungi that have been isolated from infection and specific etiology requires culture identification. Although several fungi have been isolated in the United States from persons who have mycetoma, Pseudallescheria boydii appears to be one of the most common. P. boydii is the teleomorph of Scedosporium apiospermum and Graphium eumorpum. In the other subcutaneous fungal infections, the organisms do not aggregate or coalesce into granules and have other features that may be useful in establishing etiology of those infections.

Question 7

A healthy 55-year-old man resident of Louisville, Kentucky, presented to his physician complaining of fever, headache, nonproductive cough, and chest pain of 10 days duration. As part of the history, the patient reported that he was still employed as a construction worker and for several weeks prior to becoming ill had been engaged in tearing down houses and structures as part of an urban renewal project. The most likely fungal infection considered in the differential diagnosis is

A	Blastomycosis
B	Coccidioidomycosis
C	Cryptococcosis
D	Histoplasmosis
E	Paracoccidioidomycosis
F	Sporotrichosis

Question 7 Explanation:

Although pulmonary fungal infections in the healthy host are generally asymptomatic to subclinical, in some individuals they are symptomatic (see table on the next page). The degree and duration may be related to exposure or possibly strain. The fungi associated with these infections while found to varying degrees worldwide have endemic areas. In the United States, Kentucky is in the endemic area (heaviest along the Mississippi and Ohio Rivers) for histoplasmosis, an infection of Histoplasma capsulatum. Soil with high nitrogen content such as that containing bird or bat guano promotes growth of the organisms. Excavation or activity that disturbs soil can aerosolize organisms so outdoor activities such as construction work increase the risk of exposure. In its normal habitat, the organism grows in the mold form producing both tuberculate macroconidia and microconidia. The former are distinctive structures in culture identification and the later are small enough to be inhaled into the lungs. This is the most common of the pulmonary mycoses and more than 80% of individuals in the highly endemic area have evidence of exposure. Although men and women are equally exposed, men are more likely to get symptomatic disease than women (about 4:1). The primary pulmonary infection may disseminate. Examination and culture of sputum is often negative in pulmonary infection. In the host, the organism converts to a yeast growth form and can propagate intracellularly within macrophage. The endemic area for blastomycosis overlaps that of histoplasmosis but infection is much less common and is not associated with demolition and construction exposure. In the United States, the endemic area for coccidioidomycosis is in the desert southwest along the border with Mexico with high endemicity in California and Arizona. The endemic area of paracoccidioidomycosis is in parts of South America. There is another species or variant of Histoplasma, Histoplasma duboisii. This species is found in some areas of Africa, and has a larger yeast cell in the host, and in infection, skin and skeleton are the organs most frequently affected.

Question 8

A 40-year-old woman sees her primary care physician complaining of an ulcer on her finger. She reported that it started as a red bump. Knowing that her patient was a long-time avid gardener, the physician asked if that finger had been injured by a thorn. The patient responded that she did not remember about that particular finger but she certainly had received thorn punctures in past weeks. Based on this information, which of the following is the most likely fungal etiology?

A	Fonsecaea pedrosoi
B	Malassezia furfur
C	Microsporum canis
D	Sporothrix schenckii
E	Stachybotrys chartarum

Question 8 Explanation:

Lymphocutaneous sporotrichosis, caused by S. schenckii, begins at the site of inoculation, usually on an extremity or the face. The organism is most often isolated from soil, plants, or plant products, for example straw. While the infection is global, it is more often reported from tropical and subtropical regions with areas of frequency, for example Mexico. Infection is usually associated with traumatic inoculation. Exposure is generally occupational or hobby. In the USA, the puncture is often associated with rose bush thorns. Recently the possibility of zoonotic transmission, particularly from infected cats, has received more attention. The initial lesion appears at the site of puncture. The lesion often ulcerates and may develop a raised erythematous border. Additional new lesions may appear along lymphatics that drain the primary lesion about 2 weeks after the primary lesion. Extracutaneous sporotrichosis is seen primarily in bones and joints. There is no evidence to suggest that any portal of entry besides skin is important. The primary lesion may become “fixed”, may not spread, and may resemble a malignant process. S. schenckii is a thermally dimorphic fungus growing as a mold in its natural habitat and as a yeast in infected tissue. The organisms are often sparse in tissue complicating direct examination. Other species Blastomyces, Coccidioides, Histoplasma, and Paracoccidioides are also dimorphic but rarely cause primary cutaneous infection. Fonsecaea pedrosoi is the most common cause of another subcutaneous mycosis, chromomycosis. Malassezia furfur is a component of normal skin flora that may cause superficial disease, pityriasis versicolor while Microsporum canis is a zoophilic dermatophyte that can cause tinea corporis. Stachybotrys chartarum in recent years has been associated with growth on cellulose-rich materials in water damaged buildings.

Question 9

Several young men from the local high school football team complain of a sudden onset of athlete’s foot (tinea pedis). Which of the following observations in a skin scraping will support the diagnosis?

A	Hyaline hyphae and arthroconidia
B	Pigmented hyphae
C	Sclerotic bodies
D	Spherules
E	Yeast cells

Question 9 Explanation:

The dermatophytes are a group of fungi that infect only superficial keratinized tissue (skin, hair, and nails; see the table in Question 338). Dermatophytes are probably restricted to nonviable skin because most are unable to grow at 37°C or in the presence of serum. Such lesions are among the most prevalent in the world. They are not life-threatening, but can be persistent and troublesome. The organisms form hyphae and arthroconidia in skin (see the image at the bottom of answer to Question 374). In hair, the hyphae and arthoconidia may be either inside (endothrix) or outside (ectothrix) the hair shaft. Infections by dermatophyte are termed tinea followed by the body site infected, for example tinea pedis for infection of the foot. More than one species may cause the same manifestation. In culture, macroscopic (color, texture, etc) observation of colonies and microscopic (conidia) morphology and nutritional requirements can be used in identification. The conidia that are formed are generally indicative of one of the three genera of dermatophytes. Identification of Microsporum spp. is aided by the appearance of macroconidia, Trichophyton spp. by microconidia, and Epidermophyton floccosum by distinctive macroconidia may sometimes described as “beaver tail” (see Question 358). Tinea pedis, or athlete’s foot, is the most common dermatophytosis. The organism may be acquired from desquamated epithelial cells. Classically, this occurs in common bathing areas used by groups of individuals such as athletes and shared use of towels. Among prevention efforts in athletic facilities are maintaining cleanliness of shared facilities, daily washing of towels, education of athletes, and staff on infection control for skin diseases.

Question 10

A 57-year-old obese, white female with type 1 diabetes mellitus is diagnosed with strep throat and prescribed penicillin. A week later she returns complaining of a sore mouth and white patches on the tongue. Your examination confirms the white pseudomembranous lesions. Material from the lesion is obtained and prepared for microscopic examination. Your suspicion of the most likely clinical diagnosis will be confirmed by observation of buccal epithelial cells, leukocytes, and which of the following

A	Gram-positive bacteria
B	Gram-negative bacteria
C	Hyphae with septa and acute angle branching
D	Spherules containing endospores
E	Yeast cells, hyphae, and pseudohyphae

Question 10 Explanation:

Candida albicans is the most important species of Candida and is part of the normal flora of skin, mouth, GI tract, and vagina. When host defense is compromised it can cause opportunistic cutaneous and mucosal infections such as thrush (pseudomembranous candidiasis), vaginitis, skin, and nail infections as well as candidemia and deep-seated infection. As a commensal, it is generally in the yeast form while lesions in infection generally show the additional presence of hyphae and pseudohyphae. Material from a pseudomembrane will show host cells, bacteria and mass of yeast cells, pseudohyphae, and hyphae. Since the organisms can be present as a commensal, culture is not a confirmation of infection. The diagnosis is made by clinical presentation of the pseudomembrane and the microscopic observation. This patient has two risk factors for the development of pseudo-membranous candidiasis; disturbance of the normal bacterial flora due to the use of penicillin and diabetes. Candida infection can be treated with topical nystatin or clotrimazole troches or oral fluconazole. Hyphae with acute angle branching is characteristic of Aspergillus spp., which may be recovered in sputum as may spherules containing endospores found in Coccidioides spp. But neither are associated with oral pseudomembranous lesions.

Question 11

A small brownish irregular macule on the palm of a 13-year-old girl is examined by a dermatologist in her Louisiana home town. A skin scraping from the lesion is obtained for microscopic observation and culture. Microscopic examination of the specimen shows brownish filaments or hyphae and yeast cells. The most likely diagnosis is

A	Tinea capitis
B	Tinea corporis
C	Tinea manuum
D	Tinea nigra
E	Tinea pedis

Question 11 Explanation:

Tinea nigra is a superficial infection of the stratum corneum that is usually a solitary lesion on the palms or sole that may range in color from tan to black. The lesion is chronic and asymptomatic. The infection is found most often in tropical climates and coastal regions in children and young adults with a greater incidence in women. The etiology is a dematiaceous fungus, Hortaea werneckii (previously Cladosporium, Exophiala, or Phaeoannellomyces werneckii). Dematiaceous (dark-colored) fungi produce melanin found in their cell walls. The melanin imparts a dark color to the organisms in host tissue as well as culture where colonies may appear dark brown, green-brown, or black. Microscopic examination of cultured organisms shows the pigmentation in the organism. The dark colorization of the lesion is from the fungus. The lesion may grossly resemble a malignant melanoma and more invasive procedures for this condition may be avoided by examination of skin scrapings of the lesion for fungal elements. The infection responds to topical treatment with keratolytic solutions or azole antifungal drugs. Although tinea manuum is an infection of the hand by fungi, the etiology is a dermatophyte. The other infections, tinea capitis, tinea corporis, and tinea pedis, are also infections by dermatophytes at other body sites

Question 12

You have been designated as a coordinator of construction of a bone marrow transplant unit (BMTU). There will be extensive removal of walls and floors in order to install the laminar flow rooms required for a BMTU. From the standpoint of frequency and lethality, which of the following fungi should be your biggest concern?

A	Aspergillus species
B	Candida species
C	Cryptococcus species
D	Penicillium species
E	Pneumocystis jiroveci

Question 12 Explanation:

Fungal infections are potentially serious in a bone marrow transplant unit (BMTU), Candida and Aspergillus are the most common causes of infection in BMT patients and both have a risk of mortality. However, the two differ in that Candida is a human commensal and cannot be excluded by construction practices and environmental air monitoring. On the other hand, aspergilli are ubiquitous in the environment. There are instances of multiple infections in new units that have not been monitored prior to opening or in units adjacent to construction projects. Strict precautions should be taken to exclude dust and debris from the BMTU area during construction, but in any event, the environment should be monitored for airborne microorganisms, especially Aspergillus, prior to opening the unit. Zygomycetes may also be present in the air but are a less frequent cause of opportunistic infection in the BMT patient. While Penicillium organisms are also frequent in air, the species associated with opportunistic infection, P. marneffei, is endemic in Southeast Asia where it causes disease in the AIDS patient. Pneumocystis jiroveci is an anthropophilic organism with a human reservoir and, like, Candida not excluded by construction practices. Although particularly recognized for opportunistic infection in AIDS patients, other immunocompromised patients may also have infection, including the occasional BMT patient.

Question 13

A 50-year-old man, newly employed by a commercial farm that supplies eggs and chickens to industry, develops a flu-like syndrome with fever, chills, myalgia, headache, and a nonproductive cough. He is diagnosed with histoplasmosis. A positive tissue biopsy would show the presence of

A	Arthrospores
B	Oval budding yeast cells inside macrophages
C	Spherules containing endospores
D	Tuberculate macroconidia
E	Yeast cells, hyphae, and pseudohyphae
F	Yeast cells with broad-based bud

Question 13 Explanation:

Histoplasma capsulatum is a thermally dimorphic fungus soil saprophyte that in the environment or room temperature grows as a mold that produces two types of conidia: tuberculate macroconidia and micro-conidia. Inhalation of the microconidia which are small enough to reach the lungs, initiates infection. Inhaled microconidia are engulfed by macrophages and develop into yeast forms. Most infections remain asymptomatic; small granulomatous foci heal by calcification. However, pneumonia can occur. In tissue, the yeasts are typically seen within macrophages since the organism is a facultative intracellular parasite. Arthrospores (arthroconidia) result from the fragmentation of hyphal cells. Coccidioides spp. produce arthroconidia in their natural habitat. In the infected host, this thermally dimorphic organism grows as spherules producing endospores. Another dimorphic fungus, Blastomyces dermatitidis, grows as yeast cells producing buds on a broad base in the human host. Yeast cells, hyphae, and pseudohyphae are associated with infections of Candida albicans

Question 14

A 65-year-old female patient with a long history of diabetes is brought the emergency room by her daughter with an immediate complaint of sudden swelling on the right side of the face and bleeding from the right nostril. Questioning of the patient and daughter suggests the possibility of ketoacidosis. The nasal bleeding is troublesome and a swab of the nares is rushed to the clinical laboratory for immediate attention along with blood to test for acidosis. The patient was admitted. The facial lesion became partially necrotic and there was slight protrusion of the right eye and facial paralysis. The patient died on the second day. If this patient died of a fungal infection, histopathologic examination of the lesions would most likely show…

A	Hyphae, some with arthroconidia
B	Septate dematiaceous hyphae
C	Septate hyphae with acute angle branching
D	Nonseptate hyphae
E	Narrow (<1 μm) Gram-positive filaments
F	Yeast cells

Question 14 Explanation:

This description is a typical picture of mucormycosis (also has been called zygomycosis) occurring in a diabetic patient. Etiologic agents of the genera Rhizopus, Mucor, Lichtheimia (former Absidia), Rhizomucor, and others belong to the order Mucorales. These organism have wide (10-15 μm), uneven thickness, and irregular branching hyphae that are aseptate or have rare septation. Hyphae may be sparse in infected tissue. The organisms do not contain melanin and are not dematiaceous. Hortaea werneckii, etiologic agent of tinea nigra, has dematiaceous hyphae in tissue. In skin some of the hyaline hyphae of dermatophytes may have arthroconidia. Among opportunistic molds, Aspergillus spp. have septate acute angle branching in tissue. Organisms that grow in yeast forms in the host include Histoplasma and Blastomyces while C. albicans generally has both yeast cells, hyphae, and pseudohyphae in lesions. Fungal hyphae are generally greater than 1 μm while narrow filaments are associate with bacteria such as Nocardia spp.

Question 15

A normally healthy young man in Arizona was diagnosed with coccidioidomycosis. The most likely route of infection for the etiologic agent is

A	Aspiration
B	Cutaneous contact
C	Ingestion
D	Inhalation
E	Implantation

Question 15 Explanation:

Coccidioidomycosis is a primary pulmonary infection which is asymptomatic or subclinical in about 60% of infected individuals and is initiated from inhalation of arthroconidia (arthrospores) (see the table in Question 342). Coccidioidomycosis is endemic to the dessert southwest, parts of Mexico, and Central and South America. There are two species with C. immitis concentrated in California and C. posadasii elsewhere. The infection is the same regardless of species. The organism grows as a mold in soil. Some hyphae give rise to arthroconidia, which are produced in alternating cells. When the disjunctor cells separating the arthroconidia lyse, the barrel-shaped arthroconidia are released. These conidia can be aerosolized when the soil is disturbed. Subcutaneous fungal infections such as sporotrichosis are initiated by traumatic implantation. Some individuals with coccidioidomycosis have factors that increase the risk of dissemination and extrapulmonary infection. The most common site of dissemination is the skin. However, these skin lesions are not initiated by cutaneous contact or implantation but dissemination from the original primary pulmonary infection.

Question 16

An immunocompromised patient is suspected of having aspergillosis due to A. fumigatus. Which of the following clinical conditions is most likely to occur?

A	Allergic bronchopulmonary response
B	Aspergilloma
C	Invasive pulmonary infection
D	Otomycosis
E	Wound infection

Question 16 Explanation:

Aspergillus can cause a variety of host infections or responses. In immunocompromised persons, invasive disease is the concern. Blood vessel invasion can result in thrombosis and infarction. Infection can progress rapidly and may disseminate. Invasive pulmonary infection is associated with mortality risk. The organism can infect wounds, for example burn wounds, cornea following trauma, or surgery. In pulmonary cavities (from preexisting conditions, eg, tuberculosis, histoplasmosis), “fungus ball” formation can occur, which can be seen on x-ray. Infection of the bronchi can result in allergic bronchopulmonary aspergillosis, characterized by asthmatic symptoms. Otomycosis is typically due to A. niger and is a superficial colonization with clinical features similar to other causes of external otitis.

Question 17

A 25-year-old pregnant woman, living in the San Joaquin Valley (California), experiences an influenza-like illness with fever and cough. She is diagnosed with Coccidioides infection. The most likely recommended treatment for the infection of this patient is

A	Amphotericin B or fluconazole
B	5-fluorocytosine
C	None, the infection resolves without treatment
D	Supportive treatment only for symptoms
E	Terbinafine

Question 17 Explanation:

Most individuals infected with Coccidioides spp. have asymptomatic or subclinical infections. Only about 40% have symptomatic primary pulmonary disease. In a small fraction of these individuals (about 5% of symptomatic individuals), the organism may disseminate and cause extrapulmonary disease. The risk of dissemination is greater among some population groups than others. Those at increased risk include infants and elderly, men, dark-skinned individuals, for example Filipinos, African Americans, and immunocompromised individuals including AIDS patients, and pregnant women. Women in the third trimester or immediate postpartum period are at very high risk of dissemination and death. Since the infection is self-limiting, in individuals without risk factors, antifungal therapy is not indicated although supportive therapy for symptoms may be offered. Those with risk factors or severe primary disease generally merit treatment to reduce risk of dissemination. Women in the third trimester require treatment. Amphotericin B and fluconazole are usually considered. Reports that several azoles possess teratogenic potential particularly early in pregnancy suggest that azoles should be used with care in pregnant women. A recent set of recommendations suggest amphotericin B during the first trimester and azoles later

Question 18

Months after a kidney transplant, a 45-year-old woman who was receiving immunosuppressive therapy experienced a rapid onset of respiratory insufficiency and a dry cough. High-resolution computed tomographic scanning was ordered of the lungs. There were findings of interstitial disease. Bronchoalveolar lavage was performed and the material examined by Giemsa staining. The report stated that trophic forms and cysts were observed. The most likely infecting organism is

A	Aspergillus fumigatus
B	Candida albicans
C	Pneumocystis jiroveci
D	Rhizopus arrhizus (oryzae)

Question 18 Explanation:

Pneumocystis jiroveci causes an interstitial pneumonia in immunocompromised patients and severely malnourished infants. The infection became more prominent with the AIDS epidemic as an AIDSdefining opportunistic infection in the United States. With current treatment strategies for HIV/AIDS and prophylaxis, there has been a decrease in those with access to treatment. However, it remains a leading cause of infection in those without access, who do not tolerate treatment, or who do not know of their HIV infection. Patients without HIV infection now account for the majority of cases in the developed world. These non-HIV immunocompromised patients include those with hematologic malignancies and organ transplants. Treatment-related risk factors for these patients include steroid and cytotoxic therapy. P. jiroveci (formerly P. carinii) was originally classified as a protozoan but has been reclassified in the fungal kingdom for many years. It is not a typical fungus as it lacks ergosterol in the plasma membrane, and thus antifungal drugs that target ergosterol or its biosynthesis are not effective. The organisms have not been maintained in culture and diagnosis depends on observing the organism in clinical specimens. The names of the forms that seem to be most commonly used still reflect the former protozoan designation. These are variously described as free trophic forms or trophozoites, which are haploid, and the diploid cyst that when mature may contain up to eight spores or intracystic bodies. Pneumocystis is found in humans and a variety of mammals and each fungal species appears to have host specificity so the P. jiroveci is isolated from humans and P. carinii from rats. Although the species infecting humans is now designated P. jiroveci, the name PCP (P. carinii pneumonia) has been retained by many for convenience. In AIDS patients, the onset of symptoms may be subtle with progression while in other immunocompromised patients the onset may be acute.

Question 19

Bacteria and fungi share some common mechanisms of resistance to drugs used in treatment of bacterial or fungal infection. However, bacteria have a resistance mechanism not described in fungi. This mechanism is

A	Alteration in the drug target
B	Efflux of drug
C	Inactivation of drug
D	Influx of drug
E	Overexpression of drug target

Question 20

An isolate of Candida albicans was found to be resistant to caspofungin due to mutation in the drug target which is

A	Cytosine permease
B	Ergosterol
C	P450 14-α-demethylase
D	Squalene 2,3-epoxidase
E	Subunit of β-1,3-glucan synthase

Question 21

A 25-year-old man made a self-diagnosis of athlete’s foot and purchased a product advertised to treat this condition that listed the active ingredient as tolnaftate. The mode of action of this drug is

A	Binding to membrane ergosterol
B	Incorporation into RNA leading to mistranslation and inhibition DNA synthesis
C	Inhibition of 1,3-β-glucan biosynthesis
D	Inhibition of mitosis
E	Inhibition of squalene 2,3-epoxidase
F	Inhibition P450-dependent sterol demethylase (lanosterol 14α-demethylase)

Question 21 Explanation:

Ergosterol in the fungal cell membrane is exploited by several drug classes. The squalene epoxidase is inhibited by both tolnaftate and allylamines. A later step in the pathway, a cytochrome P450 enzyme 14-α-demethylase is inhibited by azole (imidazole, triazole) class drugs. Disruption of ergosterol biosynthesis results in aberrant cell membranes. Amphotericin B targets ergosterol by binding to the sterol.

Question 22

A 37-year-old male presented with a lesion on the left leg. He reported receiving abrasions in the area 3 or 4 months earlier while on tour in Brazil. The lesion was a pink, smooth papular lesion, which he reported itched. The lesion was biopsied and the clinical pathology laboratory reported the presence of short, brownish hyphal fragments and sclerotic or Medlar bodies. The most likely diagnosis for this patient is

A	Blastomycosis
B	Chromoblastomycosis
C	Lacaziosis
D	Eumycetoma
E	Sporotrichosis

Question 23

An 87-year-old man complained that his feet hurt when he put on shoes because of his toenails. Upon inspection several toenails on both feet showed yellowing and thickening. A scraping was obtained from one nail as well as subungual debris and prepared for culture and direct examination with potassium hydroxide and Calcofluor. Microscopic examination showed fluorescent hyphae. The most likely diagnosis is

A	Tinea capitis
B	Tinea corporis
C	Tinea manuum
D	Tinea pedis
E	Tinea unguium

Question 24

A 55-year-old man from Mississippi presented with a lesion below his left eye. Examination showed a well-demarcated lesion with a raised border, scaling, and pustules. He reported no pain. Material from the edge of the lesion was submitted for histopathology and culture. The pathology laboratory reported the presence of broad-based budding yeast cells. The diagnosis for this patient is

A	Blastomycosis
B	Chromomycosis
C	Paracoccidioidomycosis
D	Penicilliosis
E	Sporotrichosis

Question 25

A 47-year-old man from Cincinnati, Ohio, suspected to have community-acquired pneumonia was treated with antibiotics. When he failed to improve, histoplasmosis was considered. Among the tests ordered were serology, direct examination, and culture of induced sputum. In culture, the microscopic morphology most useful in identification of the etiologic agent is

A	Arthroconidia
B	Microconidia
C	Sclerotic bodies
D	Spherules
E	Tuberculate macroconidia

Question 26

A 25-year-old female had surgery for a crush injury to the chest. She had a central venous catheter, was intubated, and was on a mechanical ventilator. Three days postsurgery she developed a fever and was treated empirically for bacterial infection but fever persisted. Fungemia was suspected and blood culture for fungi was ordered. Empiric antifungal therapy was initiated and the central venous catheter line was removed. Removal of the catheter is indicated because

A	Of the suspected presence of Aspergillus fumigatus biofilm
B	Of the suspected presence of Candida albicans biofilm
C	Of the suspected presence of Cryptococcus neoformans biofilm
D	Of the suspected presence of Aspergillus fumigatus planktonic organisms
E	Of the suspected presence of Candida albicans planktonic organisms
F	Of the suspected presence of Cryptococcus neoformans planktonic organisms

Question 27

A 75-year-old African American male who had recently retired to the Tucson, Arizona area from Ohio, presented with history of cough, fever, and chills for 3 weeks. Because of the recent move and ethnicity, the patient was tested for coccidioidomycosis. This infection is initiated following inhalation of structures best described as

A	Arthroconidia
B	Blastoconidia
C	Endospores
D	Spherules
E	Sporangiospores

Question 28

A 4-year-child develops tinea corporis (ringworm). The lesions clear using a preparation for treatment of athlete’s foot obtained from local drug store. The lesions reappear on the child and a playmate in a few weeks. Internet research suggested to the mother that the family pet might be the source of infection and should be taken to a veterinarian. If this is the mode of transmission, the etiology is most likely

A	Epidermophyton floccosum
B	Hortaea werneckii
C	Malassezia spp.
D	Microsporum canis
E	Trichosporon beigelii

Question 29

A patient from a small Mississippi town presented with a complaint of several weeks of productive cough, hemoptysis, weight loss, and chest pain. Radiologic findings were consistent with a pulmonary infiltrate. Among the possible diagnoses, blastomycosis was considered and culture for this organism was included in the orders for the clinical laboratory. The structure distinctive for identification in microscopic examination of a culture of the etiologic agent is

A	Arthroconidia
B	Broad-based budding yeast cells
C	Encapsulated yeast cells
D	Multiply budding yeast cells
E	Tuberculate macroconidia

Question 30

Candida albicans is isolated in blood culture from a patient in a surgical intensive care unit. This most likely source of the infecting organism is

A	A health care worker
B	A visitor
C	Ambient air
D	The patient
E	The surgeon

Question 31

A 30-year-old female of the US military was on assignment in a subtropical area. She reported to the physician with a complaint of patchy light-colored lesions on her chest and upper arms. She reported no other symptoms. Upon examination the lesions were irregular and well demarcated. Included in the differential diagnosis was pityriasis versicolor. A scraping on an affected area was obtained. If the diagnosis of pityriasis versicolor is correct, the best description of what will be observed in a positive specimen is

A	Hyaline hyphae
B	Hyaline hyphae and arthroconidia
C	Dematiaceous hyphae
D	Yeast cells with broad-based buds
E	Yeast cells and short hyphae

Question 31 Explanation:

Pityriasis versicolor is caused by species of Malassezia (this genus name is accepted over Pityrosporum that was sometimes used) that are normal skin flora. In 1996, seven taxa were recognized, of which M. furfur is only one. All seven species have been isolated from infection with geographical variation. Diagnosis is made by visualization of the fungal elements in epidermal skin scales treated with KOH with or without staining. Round yeast cells and hyphae, usually short, are present. The mixture of fungal elements has sometimes been described as “spaghetti and meatballs”. Culture is usually not necessary for these normal flora species as they can be isolated in the absence of disease. Arthroconidia are distinctive structures used in culture identification of Coccidioides spp. In dermatophyte infections, infected skin and hair will show the presence of hyaline (clear) hyphae and arthroconidia with the later particular abundant in infected hair shaft specimens. Dematiaceous hyphae are found in skin scales removed from the superficial skin infection tinea nigra. Yeast cells with broad-based budding is observed in tissue infected with Blastomyces dermatitidis.

Question 32

The overexpression of drug efflux pumps in Candida albicans is an important mechanism in reduced susceptibility to

A	Azole class drugs
B	Echinocandin class drugs
C	Flucytosine
D	Polyene class drugs

Question 33

A 53-year-old white woman with end-stage renal disease received a kidney transplant and was maintained on an immunosuppressive regimen. Three months later she had a fever (38.3°C) and was found to have acute renal failure. Renal transplant biopsy was performed. Periodic acid-Schiff staining of a biopsy section showed yeast cells and hyphae. The most likely diagnosis for this patient is infection with

A	Aspergillus fumigatus
B	Candida albicans
C	Candida glabrata
D	Cryptococcus neoformans
E	Rhizopus arrhizus (oryzae)

Question 34

Amphotericin B is noted for both its antifungal efficacy and side effects when administered to humans. The basis for the side effects is most likely

A	Binding of drug to cholesterol
B	Binding of drug to ergosterol
C	Binding of drug to phospholipids
D	Inhibition of cholesterol biosynthesis
E	Inhibition of ergosterol biosynthesis

Question 35

A fungal teleomorph is

A	Asexual reproductive form
B	Infective form for humans
C	Sexually reproductive form
D	Dormant form

Question 35 Explanation:

Asexual reproduction involves only mitosis and sexual reproduction includes meiosis. Meiosis is preceded by mating of two compatible mating types with protoplast and nuclear fusion. The form of a fungus with sexual reproduction is the teleomorph form, while the form that reproduces asexu-ally is the anamorph. Some fungi can reproduce both sexual and asexual spores and in other fungi the teleomorph form has either disappeared or not been discovered. Normally, the teleomorph name has precedence. In numerous cases with agents of human disease, the anamorph was isolated from infection and named before the teleomorph was identified in the laboratory and also named. It can be confusing, particularly to nonmycologists, when an organism has two names. Even for a fungus that can reproduce sexually, it is practice in the clinical setting to refer to organisms by their asexual names as isolated from clinical material. Even with this practice, molecular taxonomy and further study have led to some name changes. For example, Hortaea werneckii, etiology of tinea nigra, has previously been known as Cladosporium werneckii, Exophiala werneckii, and Phaeoannellomyces werneckii.

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1. A 65-year-old man was diagnosed with pseudomembranous candidiasis and given a prescription for oral fluconazole. This drug acts by:
a. Binding to membrane ergosterol
b. Incorporation into RNA leading to mistranslation and inhibits DNA synthesis
c. Inhibition of 1,3-β-glucan biosynthesis
d. Inhibition of mitosis
e. Inhibition of squalene 2,3-epoxidase
f. Inhibition P450-dependent sterol demethylase (lanosterol 14α-demethylase)

2. An AIDS patient with a CD4 count in the range 100 to 50 cells/mm3 complains of headache and neck stiffness and appears disoriented. The possibility of fungal meningitis is considered and tests for the common fungal etiology of meningitis ordered. Tests included direct examination of spinal fluid for the organism and serology. The purpose of the serology test is detection of
a. Antibody to capsular polysaccharide
b. Antibody to cell wall mannoprotein
c. Capsular polysaccharide
d. Cell wall mannoprotein

3. A 6-year-old African American girl resident of a very large US city presents to a clinic with scaly patches and areas of alopecia on the scalp with hair shafts broken off close to the scalp. The hair did not fluoresce under Wood’s light. If this child has tinea capitis, the most likely etiology is
a. Epidermophyton floccosum
b. Microsporum audouinii
c. Microsporum canis
d. Trichophyton rubrum
e. Trichophyton tonsurans

4. A 25-year-old male physical therapist trains regularly with the hope of qualifying for the Boston Marathon. He develops itching in interdigital spaces on his left foot. Suspecting tinea pedis he treats the area with an over-the-counter product. The area improves after a course of treatment but two months later reappears and again responded to the same treatment. However, there was reappearance 3 months later. If the selfdiagnosis is correct, the normal habitat of the etiologic agent is most likely described as
a. Anthropophilic
b. Geophilic
c. Zoophilic

5. A patient receiving corticosteroid treatment for lupus developed headache and fever and when she began to display some memory loss she was brought to her physician by her spouse. Considered in the differential diagnosis was cryptococcal meningitis. Which of the following, if found upon examination of cerebrospinal fluid would support that diagnosis?
a. Encapsulated yeast cells
b. Hyphae
c. Intracellular yeast cells
d. Yeast cells with multiple buds
e. Yeast cells with a broad base between mother and daughter cells

6. A 35-year-old male, a legal resident in the USA, presented with a complaint of a lesion on the bottom of his foot that was smooth and shiny and somewhat discolored. He reported that it bothered him when wearing some shoes. He reported no chronic diseases or recent illnesses and he was a nonsmoker. Travel history determined that he frequently visited relatives in India. Histopathology of the biopsy specimen showed at 2.4- mm granule surrounded by neutrophils. Tissue staining suggested that the granule contained filaments >1 μm in width. The most likely diagnosis is
a. Actinomycetoma
b. Aspergillosis
c. Chromomycosis
d. Eumycetoma
e. Phaeohyphomycosis

7. A healthy 55-year-old man resident of Louisville, Kentucky, presented to his physician complaining of fever, headache, nonproductive cough, and chest pain of 10 days duration. As part of the history, the patient reported that he was still employed as a construction worker and for several weeks prior to becoming ill had been engaged in tearing down houses and structures as part of an urban renewal project. The most likely fungal infection considered in the differential diagnosis is
a. Blastomycosis
b. Coccidioidomycosis
c. Cryptococcosis
d. Histoplasmosis
e. Paracoccidioidomycosis
f. Sporotrichosis

8. A 40-year-old woman sees her primary care physician complaining of an ulcer on her finger. She reported that it started as a red bump. Knowing that her patient was a long-time avid gardener, the physician asked if that finger had been injured by a thorn. The patient responded that she did not remember about that particular finger but she certainly had received thorn punctures in past weeks. Based on this information, which of the following is the most likely fungal etiology?
a. Fonsecaea pedrosoi
b. Malassezia furfur
c. Microsporum canis
d. Sporothrix schenckii
e. Stachybotrys chartarum

9. Several young men from the local high school football team complain of a sudden onset of athlete’s foot (tinea pedis). Which of the following observations in a skin scraping will support the diagnosis?
a. Hyaline hyphae and arthroconidia
b. Pigmented hyphae
c. Sclerotic bodies
d. Spherules
e. Yeast cells

10. A 57-year-old obese, white female with type 1 diabetes mellitus is diagnosed with strep throat and prescribed penicillin. A week later she returns complaining of a sore mouth and white patches on the tongue. Your examination confirms the white pseudomembranous lesions. Material from the lesion is obtained and prepared for microscopic examination. Your suspicion of the most likely clinical diagnosis will be confirmed by observation of buccal epithelial cells, leukocytes, and which of the following
a. Gram-positive bacteria
b. Gram-negative bacteria
c. Hyphae with septa and acute angle branching
d. Spherules containing endospores
e. Yeast cells, hyphae, and pseudohyphae

11. A small brownish irregular macule on the palm of a 13-year-old girl is examined by a dermatologist in her Louisiana home town. A skin scraping from the lesion is obtained for microscopic observation and culture. Microscopic examination of the specimen shows brownish filaments or hyphae and yeast cells. The most likely diagnosis is
a. Tinea capitis
b. Tinea corporis
c. Tinea manuum
d. Tinea nigra
e. Tinea pedis

12. You have been designated as a coordinator of construction of a bone marrow transplant unit (BMTU). There will be extensive removal of walls and floors in order to install the laminar flow rooms required for a BMTU. From the standpoint of frequency and lethality, which of the following fungi should be your biggest concern?
a. Aspergillus species
b. Candida species
c. Cryptococcus species
d. Penicillium species
e. Pneumocystis jiroveci

13. A 50-year-old man, newly employed by a commercial farm that supplies eggs and chickens to industry, develops a flu-like syndrome with fever, chills, myalgia, headache, and a nonproductive cough. He is diagnosed with histoplasmosis. A positive tissue biopsy would show the presence of
a. Arthrospores
b. Oval budding yeast cells inside macrophages
c. Spherules containing endospores
d. Tuberculate macroconidia
e. Yeast cells, hyphae, and pseudohyphae
f. Yeast cells with broad-based bud

14. A 65-year-old female patient with a long history of diabetes is brought the emergency room by her daughter with an immediate complaint of sudden swelling on the right side of the face and bleeding from the right nostril. Questioning of the patient and daughter suggests the possibility
of ketoacidosis. The nasal bleeding is troublesome and a swab of the nares is rushed to the clinical laboratory for immediate attention along with blood to test for acidosis. The patient was admitted. The facial lesion became partially necrotic and there was slight protrusion of the right eye and facial paralysis. The patient died on the second day. If this patient died of a fungal infection, histopathologic examination of the lesion would most likely show…
a. Hyphae, some with arthroconidia
b. Septate dematiaceous hyphae
c. Septate hyphae with acute angle branching
d. Nonseptate hyphae
e. Narrow (<1 μm) Gram-positive filaments
f. Yeast cells

15. A normally healthy young man in Arizona was diagnosed with coccidioidomycosis. The most likely route of infection for the etiologic agent is
a. Aspiration
b. Cutaneous contact
c. Ingestion
d. Inhalation
e. Implantation

16. An immunocompromised patient is suspected of having aspergillosis due to A. fumigatus. Which of the following clinical conditions is most likely to occur?
a. Allergic bronchopulmonary response
b. Aspergilloma
c. Invasive pulmonary infection
d. Otomycosis
e. Wound infection

17. A 25-year-old pregnant woman, living in the San Joaquin Valley (California), experiences an influenza-like illness with fever and cough. She is diagnosed with Coccidioides infection. The most likely recommended treatment for the infection of this patient is
a. Amphotericin B or fluconazole
b. 5-fluorocytosine
c. None, the infection resolves without treatment
d. Supportive treatment only for symptoms
e. Terbinafine

18. Months after a kidney transplant, a 45-year-old woman who was receiving immunosuppressive therapy experienced a rapid onset of respiratory insufficiency and a dry cough. High-resolution computed tomographic scanning was ordered of the lungs. There were findings of interstitial disease. Bronchoalveolar lavage was performed and the material examined by Giemsa staining. The report stated that trophic forms and cysts were observed. The most likely infecting organism is
a. Aspergillus fumigatus
b. Candida albicans
c. Pneumocystis jiroveci
d. Rhizopus arrhizus (oryzae)

19. Bacteria and fungi share some common mechanisms of resistance to drugs used in treatment of bacterial or fungal infection. However, bacteria have a resistance mechanism not described in fungi. This mechanism is
a. Alteration in the drug target
b. Efflux of drug
c. Inactivation of drug
d. Influx of drug
e. Overexpression of drug target

20. An isolate of Candida albicans was found to be resistant to caspofungin due to mutation in the drug target which is
a. Cytosine permease
b. Ergosterol
c. P450 14-α-demethylase
d. Squalene 2,3-epoxidase
e. Subunit of β-1,3-glucan synthase

21. A 25-year-old man made a self-diagnosis of athlete’s foot and purchased a product advertised to treat this condition that listed the active ingredient as tolnaftate. The mode of action of this drug is
a. Binding to membrane ergosterol
b. Incorporation into RNA leading to mistranslation and inhibition DNA synthesis
c. Inhibition of 1,3-β-glucan biosynthesis
d. Inhibition of mitosis
e. Inhibition of squalene 2,3-epoxidase
f. Inhibition P450-dependent sterol demethylase (lanosterol 14α-demethylase)

22. A 37-year-old male presented with a lesion on the left leg. He reported receiving abrasions in the area 3 or 4 months earlier while on tour in Brazil. The lesion was a pink, smooth papular lesion, which he reported itched. The lesion was biopsied and the clinical pathology laboratory reported the presence of short, brownish hyphal fragments and sclerotic or Medlar bodies. The most likely diagnosis for this patient is
a. Blastomycosis
b. Chromoblastomycosis
c. Lacaziosis
d. Eumycetoma
e. Sporotrichosis

23. An 87-year-old man complained that his feet hurt when he put on shoes because of his toenails. Upon inspection several toenails on both feet showed yellowing and thickening. A scraping was obtained from one nail as well as subungual debris and prepared for culture and direct examination with potassium hydroxide and Calcofluor. Microscopic examination showed fluorescent hyphae. The most likely diagnosis is
a. Tinea capitis
b. Tinea corporis
c. Tinea manuum
d. Tinea pedis
e. Tinea unguium

24. A 55-year-old man from Mississippi presented with a lesion below his left eye. Examination showed a well-demarcated lesion with a raised border, scaling, and pustules. He reported no pain. Material from the edge of the lesion was submitted for histopathology and culture. The pathology laboratory reported the presence of broad-based budding yeast cells. The diagnosis for this patient is
a. Blastomycosis
b. Chromomycosis
c. Paracoccidioidomycosis
d. Penicilliosis
e. Sporotrichosis

25. A 47-year-old man from Cincinnati, Ohio, suspected to have community-acquired pneumonia was treated with antibiotics. When he failed to improve, histoplasmosis was considered. Among the tests ordered were serology, direct examination, and culture of induced sputum. In culture, the microscopic morphology most useful in identification of the etiologic agent is
a. Arthroconidia
b. Microconidia
c. Sclerotic bodies
d. Spherules
e. Tuberculate macroconidia

26. A 25-year-old female had surgery for a crush injury to the chest. She had a central venous catheter, was intubated, and was on a mechanical ventilator. Three days postsurgery she developed a fever and was treated empirically for bacterial infection but fever persisted. Fungemia was suspected and blood culture for fungi was ordered. Empiric antifungal therapy was initiated and the central venous catheter line was removed. Removal of the catheter is indicated because
a. Of the suspected presence of Aspergillus fumigatus biofilm
b. Of the suspected presence of Candida albicans biofilm
c. Of the suspected presence of Cryptococcus neoformans biofilm
d. Of the suspected presence of Aspergillus fumigatus planktonic organisms
e. Of the suspected presence of Candida albicans planktonic organisms
f. Of the suspected presence of Cryptococcus neoformans planktonic organisms

27. A 75-year-old African American male who had recently retired to the Tucson, Arizona area from Ohio, presented with history of cough, fever, and chills for 3 weeks. Because of the recent move and ethnicity, the patient was tested for coccidioidomycosis. This infection is initiated following inhalation of structures best described as
a. Arthroconidia
b. Blastoconidia
c. Endospores
d. Spherules
e. Sporangiospores

28. A 4-year-child develops tinea corporis (ringworm). The lesions clear using a preparation for treatment of athlete’s foot obtained from local drug store. The lesions reappear on the child and a playmate in a few weeks. Internet research suggested to the mother that the family pet might be the source of infection and should be taken to a veterinarian. If this is the mode of transmission, the etiology is most likely
a. Epidermophyton floccosum
b. Hortaea werneckii
c. Malassezia spp.
d. Microsporum canis
e. Trichosporon beigelii

29. A patient from a small Mississippi town presented with a complaint of several weeks of productive cough, hemoptysis, weight loss, and chest pain. Radiologic findings were consistent with a pulmonary infiltrate. Among the possible diagnoses, blastomycosis was considered and culture for this organism was included in the orders for the clinical laboratory. The structure distinctive for identification in microscopic examination of a culture of the etiologic agent is
a. Arthroconidia
b. Broad-based budding yeast cells
c. Encapsulated yeast cells
d. Multiply budding yeast cells
e. Tuberculate macroconidia

30. Candida albicans is isolated in blood culture from a patient in a surgical intensive care unit. This most likely source of the infecting organism is
a. A health care worker
b. A visitor
c. Ambient air
d. The patient
e. The surgeon

31. A 30-year-old female of the US military was on assignment in a subtropical area. She reported to the physician with a complaint of patchy light-colored lesions on her chest and upper arms. She reported no other symptoms. Upon examination the lesions were irregular and well demarcated. Included in the differential diagnosis was pityriasis versicolor. A scraping on an affected area was obtained. If the diagnosis of pityriasis versicolor is correct, the best description of what will be observed in a positive specimen is
a. Hyaline hyphae
b. Hyaline hyphae and arthroconidia
c. Dematiaceous hyphae
d. Yeast cells with broad-based buds
e. Yeast cells and short hyphae

32. The overexpression of drug efflux pumps in Candida albicans is an important mechanism in reduced susceptibility to
a. Azole class drugs
b. Echinocandin class drugs
c. Flucytosine
d. Polyene class drugs

33. A 53-year-old white woman with end-stage renal disease received a kidney transplant and was maintained on an immunosuppressive regimen. Three months later she had a fever (38.3°C) and was found to have acute renal failure. Renal transplant biopsy was performed. Periodic acid-Schiff staining of a biopsy section showed yeast cells and hyphae. The most likely diagnosis for this patient is infection with
a. Aspergillus fumigatus
b. Candida albicans
c. Candida glabrata
d. Cryptococcus neoformans
e. Rhizopus arrhizus (oryzae)

34. Amphotericin B is noted for both its antifungal efficacy and side effects when administered to humans. The basis for the side effects is most likely
a. Binding of drug to cholesterol
b. Binding of drug to ergosterol
c. Binding of drug to phospholipids
d. Inhibition of cholesterol biosynthesis
e. Inhibition of ergosterol biosynthesis

35. A fungal teleomorph is
a. Asexual reproductive form
b. Infective form for humans
c. Sexually reproductive form
d. Dormant form

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