mICROSCOPIC IDENTIFICATION OF MAJOR PATHOGENS
The image in the upper right indicates the mold form of which dimorphic fungus?
Coccidioides immitis
The fungus illustrated in this photomicrograph was recovered from an induced sputum specimen from a 74-year-old man with chronic obstructive pulmonary disease. This isolate is most likely:
A contaminant
The spherical, finely-spiked macroconidia of Sepedonium species appear similar to those microscopically seen in the mold form of Histoplasma capsulatum. By what characteristic may Sepedonium be excluded?
Ability to produce yeast conversion when colonies are incubated at 35 - 37 degrees C
The border to border extension of the mycelium as illustrated in the top photograph is characteristic of one of the Zygomycetes. Although a light yellow green pigmentation of the mycelium is observed, the identification of the isolate depends on the presentation of the fruiting body observed in the bottom photomicrograph. From these observations, select the name of this isolate from the list of multiple choices.
Absidia species
Illustrated in the top image is 4 day growth of a smooth, glabrous colony with a light tan yellow surface, cultured from a patient who developed a subcutaneous abscess at the site where a bone marrow transplant was administered. The bottom image is a photograph of a methylene blue stained mount presenting long, delicate conidiophores at the tips of which are produced loose clusters of thin elongated conidia in an oriental letter or "diphtheroidal" pattern. With these observations, what is the most likely identification?
Acremonium sp.
The microscopic illustration demonstrates the golden-brown pigmented conidia and macroconidia of the following mold:
Alternaria
Illustrated in the top image is a relatively rapidly growing 4-day-old colony on Sabouraud's dextrose agar incubated at 30o C. This colony was recovered as part of an environmental study. The colony has a wooly surface with distinctive black pigmentation both centrally and at the periphery, which was also visible when observed on the reverse of the Petri dish. Based on the microscopic presentation shown in the bottom image, identify this rapidly growing dematiaceous fungus.
Alternaria species
Based on the structures observed in this microscopic image, the most probable identity of the fungus recovered from an induced sputum specimen is:
Aspergillus species
Which of the following species of hyaline molds produce conidia in chains?
Scopulariopsis species
Which of the following morphological features would correspond to Phialophora verrucosum?
Urn or vase shaped phialides
Illustrated in this photomicrograph of a lactophenol blue preparation of a urine sediment is a cluster of yeast cells that were presumptively identified as Cryptococcus species. Further characteristics that may assist in confirming this identification are:
Strong phenoloxidase activity
What is the phenotypic property of Saccharomyces yeast species that is helpful in establishing its species identification?
Ascospore production
The fungal colonies illustrated on the left image grew to maturity in 4 days. The isolate was recovered from the expectorated sputum of an elderly immune-compromised patient. The image on the right is the microscopic appearance of a lactophenol cotton blue stained mount prepared from a small sample from the surface of the colony. Note that microscopically the entire surface of a smooth spherical vesicle is surrounded by a row of phialides giving rise to small conidia. Which Aspergillus species is represented by these observations?
Aspergillus flavus
Choose the fungi that may be identified to a genus level, when the fungal structures that are seen in this photomicrograph are present in tissue sections.
Aspergillus species
Illustrated in the upper left image of the composite photograph is a 3 day old colony with a central, granular yellow surface (resembling cinnamon) surrounded by a broad white apron. This colony was recovered from a fungus ball infection of the lung. The microscopic presentation of a methylene-blue stained mount of a sample from the surface of the colony is observed in the upper right and lower left images. In the lower right image taken of a direct mount of the colony showing vegetative hyphae. With these observations, select from the list of multiple choice responses the correct fungal species as presented.
Aspergillus terreus
Illustrated in the top image is a 3.5-day-old brown/black, smooth yeast colony that is usually considered a contaminant when recovered in laboratory cultures. Reports of verrucose skin and visceral infections with this black yeast have been reported. The bottom image illustrates the microscopic view as prepared in a mount prepared from the surface of the colony. Note the background dark-staining hyphae from which are produced small, elliptical conidia. Select from the choices below the correct presumptive identification of this isolate.
Aureobasidium pullulans
The following is a systemic, dimorphic genus that characteristically produces barrel-shaped arthroconidia separated by dysjunctor cells:
Coccidiodes immitus
The following are described as rapid growing, opportunistic fungi that are differentiated based on the presence of sporangiospores, the shape of the columella, presence or absence of rhizoids, and the location of the rhizoids on the stolon.
Mucorales species
The top image shows a 5-day old entire colony with distinct outer borders that was incubated at 30° C. The surface is a delicate silky, light gray-white mycelium. The reverse of the colony appears white. This appearance is non-specific. The bottom image is a photomicrograph of a lacto-phenol blue stained mount of a small inoculum taken from the surface of the colony. What is the most likely identification?
Beauveria
Illustrated in the photograph to the right is a lactophenol cotton blue preparation from a culture of a dematiaceous fungi. This fungi is known to cause phaeohyphomycosis and can be found in sites such as subcutaneous tissue, brain, eyes, and bones. Which of the following fungi is represented?
Bipolaris species
Illustrated in the top photomicrograph is a 4 day old colony growing on Sabouraud's dextrose agar with a smooth dark gray to black surface surrounded by dark gray and white peripheral bands. The colony morphology is not distinctive. The identification is made by observing the septate hyphae and conidia as microscopically observed in the lactophenol cotton blue stained mount obtained from the surface of the colony as illustrated in the bottom photomicrograph. From these observations, select the most probable fungi.
Bipolaris species
The production of polar germ tubes is a characteristic that is associated with which of these dematiaceous fungi?
Bipolaris species
Identify the species of dimorphic fungi in its yeast form as observed under the microscope in this image.
Blastomyces dermatitidis
Illustrated in the top image is a 10-day-old colony growing on the surface of Sabouraud Dextrose with Brain Infusion (SABHI) agar, incubated at 30° C, recovered from an induced sputum sample obtained from a 42-year-old Mid-western farmer. The colonies are not genus/species specific, and appear as a mold with a delicate, silky, cob-web like yellow-white mycelium. The species identification is made by observing the Lactophenol blue-stained tease mount preparation illustrated in the bottom image. With these observations, select the presumptive identification of this isolate from the choices shown below.
Blastomyces dermatitidis
This image illustrates a lactophenol blue mount prepared from a mold recovered after 7 days incubation on brain heart infusion broth. The individual microconidia, each borne by a delicate conidiophore, suggests the mold form of the following organism:
Blastomyces dermatitidis
Which of the following dimorphic molds produces spherical or oval conidia, each supported by an individual conidiophore ("lollipop") as represented in the image on the right?
Blastomyces dermatitidis
Yeast colonies, as illustrated in the top image, can be cultured in the mycology laboratory either by transferring samples from growing colonies to enriched agar incubated at 35o - 37o C, or by setting up a second culture for incubation at the elevated temperature. The yeast colonies appear smooth and pasty, off-white pigmentation. The species identification is made by observing the morphology of a yeast cell as observed in lactophenol blue-stained mounts as shown in the bottom image. With these observations, select the correct presumptive identification of this isolate from the choices listed below.
Blastomyces dermatitidis
All of the following observations are consistent with the laboratory identification of Cryptococcus neoformans, EXCEPT:
Negative urease test.
This photomicrograph was prepared from tease mounts of 3 day-old smooth, white yeast colonies obtained from an aspirate of nasal fluid of a middle aged patient with sinusitis. Note the clusters of small blastoconidia along the pseudohyphae and also the larger spherical chlamydospores (arrow), as observed in the right lower corner. From the multiple choices below, select the identification of this yeast isolate.
Candida albicans
The smooth, pasty appearing 72 hour yeast colonies growing on blood agar shown in the upper image are non-specific and further studies must be performed to make the identification. One of these studies is a cornmeal agar preparation is illustrated in the bottom photomicrograph in which tiny, uniform, spherical cells are arranged in tight clusters. This yeast is commonly recovered from urinary tract infections. Select the most likely yeast isolate.
Candida glabrata
The growth of yellow-white yeast colonies with a smooth or hair-like surface within 2 - 3 days on non-selective culture media generally requires further procedures to make a presumptive identification. Microscopic observation of the subculture of colonies growing on cornmeal agar is one such approach, as illustrated in the photomicrograph. Note the "logs in stream" arrangement of elongated blastoconidia. From the multiple choices, select the name of the presumptive yeast identification.
Candida kefyr
This yeast has been found in respiratory secretions, the vagina, urine, gastric washing and the oropharynx but is mainly thought to cause vaginitis and urinary tract infections. Growth on Cornmeal Tween 80 agar demonstrates elongated blastoconidia that lie parallel to pseudohyphae (like logs on a stream).
Candida kefyr (pseudotropicalis)
The growth of yellow-white yeast colonies with a smooth or hair-like surface within 2 - 3 days on non-selective culture media generally requires further procedures to make a presumptive identification. Microscopic observation of the subculture of colonies growing on cornmeal agar is one such approach, as illustrated in the photomicrograph. Note the spider-like colonies that appear along the streak line. From the multiple choices, select the name of the presumptive yeast identification.
Candida parapsilosis
The type of sporulation illustrated in this photomicrograph of a dematiaceous fungus is:
Cladosporium
The dimorphic molds exist in both mold and yeast forms depending on the temperature of incubation. In the laboratory, when cultures are incubated at 30o C, all of the dimorphic fungi will produce mold colonies, usually within 10 - 14 days. When cultures are incubated at 35o - 37o C, yeast colonies develop usually within 3 - 5 days, with the exception of one of the dimorphic species. From the options shown below, select the genus that does not produce yeast colonies when cultures are incubated at the higher temperature.
Coccidioides immitis
Illustrated in the upper left image in the composite photograph is a brown pigmented scaling lesion of the skin involving the distal forearm and anterior wrist interspersed with focal dark circumscribed nodules. The image to the upper right are small white yeast colonies with smooth surfaces. The lower images illustrate the microscopic appearance of fluid aspirated from one of the cystic lesions illustrating distinctive yeast cells. Based on these results, select the name of the infection as illustrated.
Cryptococcosis
The top image shows the microscopic appearance of yeast cells within a colony growing on cornmeal tween 80 agar. These same cells may also be observed in a tissue section (bottom image) taken from an area of inflammation. The tissue section is stained with Gomori Methanimine Silver and shows a clear area around the cells. Which of the following organisms could be the cause of this inflammation?
Cryptococcus neoformans
The India ink preparation is used for presumptive identification of which organism?
Cryptococcus neoformans in CSF
The oval or curved multi-celled, dark-staining macroconidia divided by transverse septa seen in this image is characteristic of:
Curvularia species
A dermatophyte that produces thin-walled, two or three-celled macroconidia in clusters, and no microconidia, most likely belongs to the genus:
Epidermophyton
Illustrated in the top left image of the composite photograph is a well-circumscribed, actively progressing pink scaling lesion on the groin, termed tinea cruris or more commonly "jock itch". Illustrated in the lower left frame is a 3-day old colony growing on SABHI agar with a gray-yellow smooth surface with radiating spicules at the periphery. The microscopic features are presented in the right upper and lower photomicrographs of the slide mounts. Select the identification of this dermatophyte.
Epidermophyton floccosum
Illustrated in the top photograph is a 4-day growth of silky, light gray-white to yellow colonies grown on Sabouraud's dextrose agar incubated at 30° C, recovered from an "athlete's foot" infection (tinea pedis) of a young football player. Note the projection of delicate hyphae to the periphery of the colonies. The identification can be made by observing the conidia formations in the lactophenol blue stained mount prepared from the surface of one of the colonies. With these observations, select the species identification from the multiple choices.
Epidermophyton floccosum
Illustrated in the upper image is an 8-day-old old green black colony growing on the surface of Sabouraud Dextrose Brain Heart Infusion (SABHI) agar, obtained from a superficial skin lesion characteristic of chromomycosis. The black pigment extends to the reverse side of the colony. The identification can be made by observing the characteristic fruiting body as illustrated in the lower image. What is the most likely identification of this fungi?
Exophiala jeanselmei
Which of the following dematiaceous fungal species produce conidia in clusters?
Exophiala species
Illustrated in this image is the fruiting head of one of the fungal agents of chromomycosis. Note the small clusters and short chains of elliptical conidia produced from the tip of a conidiophore. Which of the following choices best represents the type of sporulation illustrated in this image?
Exophiala sporulation
Illustrated in the top photograph is a circumscribed colony after 3 days of incubation at 30o C. The consistency is cottony to wooly and pigment ranges from gray to deep brown. A light pigmented outer apron is seen at the margins of growth. The reverse is dark brown to black, resulting from a darkly pigmented mycelium. As the colony morphology is not species specific, the identification can be made by the appearance of the macroconidia observed in a stained tease mount made from the surface of the colony as observed in the bottom photomicrograph. From these observations, select from the multiple choices the name of this fungus.
Exserohilum species
A group of relatively slow growing fungi with distinctive dark brown to black colonies are the cause of infections of the skin known as Chromoblastomycosis. Clinically they appear as roughened multicolored verrucous vegetations, most commonly spreading over the dorsal surfaces of the lower legs and feet following penetrating injuries. A presumptive diagnosis of a fungus infection can be made on H & E - stained sections of a tissue biopsy by identifying oval/spherical bodies grouped in small clusters termed "sclerotic bodies" (more colloquial known as "copper pennies"), as illustrated in the top image. Dark gray-black pigmented mold colonies are grown in culture obtained from a biopsy specimen. The dark pigment is produced by deeply pigmented hyphae from the production of melanin, as illustrated in the bottom image. Note the branching conidiophores borne from the tips of hyphae giving rise to short chains of oval conidia. Select the presumptive species identification of this isolate.
Fonsecaea pedrosoi
Illustrated in the top image is a slow-growing, 8-day-old colony with velvety brown, deep radial grooves and a black periphery consistent with one of the agents of chromomycosis. In the bottom image, note the conidiophores produced from the sides of the hyphae producing short, branching phialides, giving rise to clusters of elliptical conidia. From the list of choices shown below, select the correct presumptive identification of this isolate.
Fonsecaea pedrosoi
In tissues infected with Histoplasma capsulatum, which of the following is usually true?
Fungus is usually intracellular
Illustrated in the upper image is a 4 day growth of a fungus colony on Sabouraud's dextrose agar. Note the cottony to woolly surface, and the distinctive lavender, pink pigmentation. The lower image is of a lactophenol cotton blue pigmented view of long, narrow multi-celled macro-conidia that are sickle-shaped. Based on these observations, select the genus identification of this isolate.
Fusarium
This rapidly growing hyaline fungus is the most common cause of Keratomycosis (an infectious disease of the cornea). The colonies can range in color from rose to mauve to orange. This organism is commonly recovered from blood and grows on sabourauds dextrose agar with brain heart infusion. The microscopic appearance shows abundant banana or canoe shaped macroconidia. What fungus causes this disease?
Fusarium species
Illustrated in the top photograph is a 4-day-old white to cream-colored colony with a yeast-like background, but with the surface having a delicate silk-like consistency. Such colonies may be recovered as a contaminant in laboratory cultures. The identification is illustrated in a cornmeal agar mount shown in the bottom photograph. From these observations, the MOST likely identification of this yeast-like isolate is:
Geotrichum candidum
The hyaline mold illustrated in this photomicrograph can be identified as:
Gliocladium species
An uncommon isolate in clinical laboratories, the gray-white colony with a hairy mycelium as illustrated in the top image is non-specific. The identification is made by microscopically observing acid-fast ascospores as seen in the bottom image. Select the fungal species characteristic of this isolate.
Hansenula anomala
Illustrated in the top image is the surface of a blood agar culture plate incubated at 35°C for 3 days. Note the growth of tiny smooth, pasty, yellow-white yeast colonies. Although a presumptive identification might be made from the macroscopic morphology, confirmation is made by observing the yeasts forms in the lactophenol stained mount observed in a tease mount prepared from one of the colonies. From these observations, what is the most likely identification?
Histoplasma capsulatum
In the late 1990's, an outbreak of pneumonia was experienced by several high school students involved in a clean-up day held in a Midwestern community. One student experienced a severe disseminated infection. The colony growing on Sabouraud Dextrose with Brain Heart Infusion (SABHI) agar and incubated at 30o C and shown on the top photograph was recovered from an induced sputum specimen. The colony matured in 8 days, presenting a hair-like, cottony surface mycelium. The identification was confirmed by observation of the lactophenol tease mount obtained from the surface of the mycelium. From the list of choices below, select the name of this isolate
Histoplasma capsulatum
Large, one-celled, smooth-to-tuberculate macroconidia, and smooth or echinulate microconidia are typical of mycelial phase growth of which organism?
Histoplasma capsulatum
The colonies shown in the upper image were obtained on blood agar from a sputum specimen after 10 days incubation at 30°C. The lower image is a photomicrograph of a lactophenol blue mount made from a portion of the colony. The delicate cob-web appearance of the colonies on blood agar (upper image) and the production of macroconidia with a conspicuous prickly surface as seen in the lower image are characteristic of:
Histoplasma capsulatum
photomicrographs prepared from histological sections of a duodenal biopsy obtained from a patient with AIDS who was experiencing chronic diarrhea. Tiny intra-cytoplasmic spores are observed in both the left hand PAS stained and on the right Methylene blue-stained sections. The spores are best visualized in the PAS-stained section on the left (arrow). Stool specimens had been negative for parasites or bacterial pathogens. The acid-fast is negative with a positive Weber stain (Chromotrope 2R. Fast Green, phosphotungistic acid) confirming an identification. From the list of multiple choices, select the most probable presumptive identification.
Microsporidium species
Under a Woods' lamp, infected hair strands from several children with tinea capitis showed green fluorescence, and subsequent cultures grew fungi with aerial mycelia and terminal chlamydospores. These isolates are most likely:
Microsporum audouinii
Illustrated in the photograph is a classic example of "ringworm" as may be observed in a young child, possibly contracted from the spores of an infected dog or cat. The identification of the dermatophyte causing this infection is illustrated in the lactophenol blue stained mount photomicrograph. Select the dermatophyte causing this type of infection.
Microsporum canis
Illustrated in the top photograph is the appearance of a 4-day old fugal colony cultured from a "ringworm" cutaneous infection. Although the appearance of the colony may suggest a presumptive identification, microscopic mounts prepared from the surface hyphae must be examined, as observed in the lacto-phenol blue stained tease mount in the bottom photomicrograph. With these observations, select from the multiple choices the identification of this dermatophyte.
Microsporum canis
The 4-day old colony recovered on Sabouraud's dextrose agar, as illustrated in the top photograph. The specimen was taken from a skin infection incurred by a 45 year old farmer. The microscopic appearance, obtained from the surface mycelium of the colony, is illustrated in the lactophenol blue mount in the bottom image. What is the fungal isolate shown?
Microsporum gypseum
The fungal colony illustrated in the upper image was observed after 4 days incubation at 30oC and recovered from dialysis fluid of a 60-year-old patient who had been receiving multiple antibiotics for treatment of bacterial peritonitis. The lower image is of a microscopic view of a lactophenol blue stained mount taken from a small sampled of the surface of the colony. Note the distinctly pointed phialides from which long chains of small, spherical conidia are derived. What is the appropriate identification based on the colony morphology and microscopic features as observed in the lactophenol stained preparation?
Paecilomyces
Identify the species of dimorphic fungi in its yeast form as observed under the microscope.
Paracoccidioides brasiliensis
The colonies observed on the agar surface in the top photograph represent 4 day-old yeast colonies converted from a mold colony suspicious for a dimorphic fungus. The identification is made by microscopically observing the characteristic morphology of the yeast cells as illustrated in the bottom photomicrograph. What is this species?
Paracoccidioides brasiliensis
The yeast forms of which of the following species of dimorphic fungi (represented in the image on the right) can be described as large yeast cells with multiple buds that are attached by narrow necks, giving the appearance of a "mariner's wheel?"
Paracoccidioides brasiliensis
The fungal colony illustrated in the upper image, observed after 4 days incubation at 30°C, was recovered from dialysis fluid of a 60 year-old patient who had been receiving multiple antibiotics for treatment of bacterial peritonitis. The colony surface is cottony and green in pigmentation. The lower image is of a methylene-blue stained section of fruiting heads observed in a mount prepared from a small sample of the colony surface. Based on the colony morphology and microscopic features, what is the genus identification of this isolate.
Penicillium
The hyaline mold colony represented in the composite picture is approximately 8 days old. The most likely genus is: Please s
Penicillium
In observing the slow-growing, 7-day-old dark brown colonies growing on Sabouraud Dextrose with Brain Heart Infusion (SABHI) agar, note that the black pigment extends to the reverse of the colony. This provides a presumptive indication of one of the fungi involved in chromoblastomycosis. The species identification of this fungus can be made by observing the distinctive fruiting heads illustrated in the bottom image. Select the identification of the fungal species.
Phialophora verrucosa
The segmented, dark-staining grains seen in this photomicrograph are most commonly seen in cases of chromoblastomycosis. Which of the fungal species listed below is known to cause this disease?
Phialophora verrucosa
This organism is a slow-grower on Sabouraud Dextrose Brain Heart Infusion (SABHI) agar. It was recovered from a chronic recurrent cyst of the skin of the lower leg. The brown hair-like surface pigmentation appears brown-black when observed on the reverse of the colony. The identification is made by the microscopic appearance of fruiting heads. The image shows hyphae that are dark with flask-shaped phialides which form on the tips of the condiophores. What is the name of this fungus? Image courtesy of the CDC
Phialophora verrucosa
Often recovered from puncture wounds of the fingers, wrists and arms, illustrated in the top photograph is the 4 day growth on SABHI agar after incubation at 30o C. The colony is circumscribed, yellow, rough and wrinkled centrally, surrounded by narrow smooth, white circular growth with a distinct brown-black outer border. The identification can be made by observing the lactophenol blue stained fruiting heads in the bottom photomicrograph. From these observations, select the name of this fungal isolate.
Sporothrix schenckii
In this photomicrograph, several dematiaceous hyphae with long, flask-shaped, tapered phialides that have flat saucer-like terminus are seen (arrow). This feature is most characteristic of which of the following fungal species?
Pleurostomophora richardsiae
When working up a culture, Scedosporium species may presumptively be identified if colonies have a "house mouse" gray appearance and microscopically observed are long delicate condiophores from the tips of which are produced a single oval conidium ("lollipop"). In some cases, further examination of the microscopic mount may reveal the branching, sheath-like arrangement (graphium form) of conidiophores as seen in the top image, and/or the spherical conidia-containing ascospores seen in the lower image. From the multiple choices, indicate the fungal species to be recognized.
Pseudoallescheria boydii
This gram stain smear was prepared from a sputum specimen and is viewed under oil immersion (1000X). What is the structure indicated by the arrow?
Pseudohyphae/yeast
The type of sporulation of the dematiaceous mold that is illustrated in this photomicrograph is called:
Rhinocladiella
Observed in the image is the microscopic appearance of a sporulation representative of one of the dematiaceous fungi causing chromomycosis. Note that spherical conidia are being produced laterally from the sides of a conidiophore. Which of the following choices represents the type of sporulation illustrated in this image?
Rhinocladiella sporulation
The colony shown in the upper image was recovered from the nasal exudate of a 28-year-old construction worker with sinusitis. The colony grew in 3 days on SabHI agar (combination of Sabouraud dextrose and BHI agar) incubated at 30o C. Note the border-to-border extension of the surface mycelium. As the colony is not species-specific, the identification of this isolate can be made by observing the lower, lactophenol blue-stained image. From these observations, select the identification of this isolate. Please sele
Rhizopus species
The hemotoxylin and eosin (H & E) stained tissue reaction in the top photomicrograph reveals a chronic inflammatory reaction with irregular sized, non-septate fungal hyphae, suggestive of one of the Zygomycetes. In practice, a sample of the tissue specimen would be sent to the mycology laboratory to substantiate the diagnosis. What is the illustrated fungal species, recovered from the specimen, seen in the bottom, microscopic photomicrograph?
Rhizopus species
The pink-red, yeast-like colonies shown in the photograph together with the production of budding yeast cells singly and in loose clusters in the absence of hyphal formation is characteristic of which of the yeast listed below? (In the past, recovery in laboratory culture this organism was considered a contaminant; however, more recently it has been listed as an "emerging" agent of infection and cannot be considered as insignificant.)
Rhodotorula mucilaginosa
What is the MOST likely identification of a pink yeast isolate, recovered from respiratory secretions of a patient with AIDS, that gave the following results? Germ tube - negativeUrease - positiveBlastospores - positiveArthrospores - negative
Rhodotorula spp.
The illustrated organism is the anamorph stage of Pseudoallescheria boydii that may cause pulmonary fungus ball infection, mycetomas, endocarditis, and other disseminated infections.
Scedosporium species
An acid-fast bacillus is isolated and produces an orange pigment when grown in either the light or the dark. Which type of organism has most likely been isolated?
Scotochromogen
The upper image is a 4 day old colony grown on Sabouraud's Dextrose agar, recovered from a bacterial culture that was considered to be a "contaminant". The lower image is a high power image of a methylene-blue stained mount prepared from the surfaces of the colony. With these observations, select the fungus genus from the multiple choices as listed.
Sepedonium
The dermatophytic fungus shown in this photomicrograph, is recovered from a ringworm lesion of the skin of the back of the hand of an 8-year-old boy. What was the most likely source for this fungus?
Soil in the back yard
In cases where separate fungal cultures are incubated at both 30° C and 35°-37° C, a dimorphic yeast form may develop within 3-4 days as illustrated in the top photograph. The isolate is commonly recovered from puncture wounds of the fingers, wrists or arms among rose gardeners. The yeast colony has a smooth outer white border surrounding an inner pigmented center of growth that appear to be hyphal strands. What is the yeast identified by observing the microscopic features as illustrated in the bottom lactophenol stained mount?
Sporothrix schenckii
The ovoid microconidia arranged in a daisy-head pattern at the tip of a straight conidiophore, observed in the photomicrograph on the right, is characteristic of which of the following dimorphic molds?
Sporothrix schenckii
The border to border, light tan delicate cottony grown in 3 days on SABHI agar incubated at 30° C as illustrated in the top photograph is characteristic of one of the Zygomycetes. As the colony morphology is non-selective, the identification of this isolate is made by observing the characteristic fruiting head as illustrated in the bottom lactophenol blue stained photomicrograph. From these observations, select the name of this isolate from the list of multiple choices.
Syncephalastrum species
Illustrated in the upper image is a 6-day-old colony growing on the surface of Sabouraud Dextrose agar. Note the distinct light green and pink granular colony surrounded with a reddish margin with diffusion of the wine-red pigment into the agar. This type of colony may be recovered from a sputum specimen of a person with travel history to Southeast Asia. The lower image is of a microscopic mount stained with lactophenol blue. From these characteristics, select the identification of this fungal isolate.
Talaromyces (Penicillium) marneffei
The colony illustrated in the top image developed after 4 days of growth on Sabouraud's dextrose agar. Note the extension of the outer margin to the rim of the Petri dish. The bottom image 2 is a methylene-blue stained image of an inoculum obtained from the surface of the colony. From these characteristics, select the fungus genus from the multiple choices.
Trichoderma
The arrows in the image on the right point to single, long, tapered phialides that extend laterally from either side of the hyphae. This microscopic presentation is an identifying feature of which fungi?
Trichoderma species
Illustrated in the top photograph is a 5-day culture on Sabouraud's dextrose agar obtained from a skin scraping specimen of a "ringworm" lesion from the groin of a 25 year old male. The appearance of a wine red pigment diffusing into the agar at the margins of a cottony white colony is distinctive. The accompanying microscopic features are observed in the accompanying lactophenol blue stained mount illustrated in the lower photomicrograph. From the multiple choices, select the species name of the fungal isolate as illustrated.
Trichophyton rubrum
The profusion of tiny microconidia lining up along the hyphae in this photomicrograph is characteristic of which of the following organisms?
Trichophyton rubrum
The scaling, pink-white appearance of the foot shown in the photograph is characteristic of "Athlete's Foot", a skin infection incurred by athletes after barefoot walks to and from the shower stall. A cottony gray-white fungal colony grew in 5 days from a skin scraping. The identification was made by the microscopic appearance of a mount made from the colony as illustrated in the photomicrograph. From these observations, select the name of the fungal species.
Trichophyton rubrum
Illustrated in the top photograph is the picture of a yellow to buff colored colony, suede-like in consistency, recovered from a hairless inflammatory lesion of the skin of the scalp of a young male athlete. The more definitive identification can be made from observation of the lactophenol blue mount illustrated in the bottom photomicrograph, prepared from a small sample of the colony surface mycelium. Based on these observations, select from the multiple choices the presumptive identification.
Trichophyton tonsurans
A soft, yellow to pale brown nodule is found growing around the hair shaft of an individual from a tropical location. On direct microscopic examination, hyaline hyphae with numerous rectangular arthroconidia were observed. The presence of the arthroconidia aid in differentiating this organism from other yeast. The most likely identification is:
Trichosporon species
The colony shown in the top image developed on Sabouraud's agar in 3 days when incubated at 30° C. When recovered in laboratory cultures, the source is either from the environment or a commensal contaminant. The colony has a woolly brown, gray black and white circumferential appearance, with the gray-black pigment being observed from the reverse side of the petri dish. From the microscopic appearance as illustrated in the bottom photograph, what is the most likely identification?
Ulocladium species
India Ink is used to:
Visualize capsule
Illustrated in the composite photograph is an inflammatory reaction of skin with erythema and micro-pustule formation, most consistent with a dermatophyte infection. The lactophenol blue mount was prepared from a 4-day old colony grown from the skin lesion as shown. The accompanying lactophenol blue microscopic mount illustrates small, spherical micro conidia arranged in loose clusters along the sides of thin hyaline hyphae. The species identification can be confirmed by the positive urease reaction as shown. What is the appropriate identification?
trichophyton mentagrophytes
