Mycology: Hyaline and Dematiaceous Fungi

Authors: Elmer W. Koneman, MD and Margaret Reinhart, MS, MT(ASCP)
Reviewer: Julie Ann West, PhD, MLS(ASCP)CM, SM(ASCP)CM
See all available Compliance & CE courses »

Continuing Education Credits

P.A.C.E.® Contact Hours: 2 hour(s)

Florida Board of Clinical Laboratory Science CE Credit Hours

Florida Board of Clinical Laboratory Science CE - General (Microbiology/Mycology/Parasitology): 1.5 hour(s)

(based on 148 customer ratings)

Mycology: Hyaline and Dematiaceous Fungi uses an interrogative, question-and-answer, approach to direct and instruct the participant in identifying hyaline and dematiaceous fungi. Numerous images enhance the descriptions of identifying characteristics by illustrating the appearance of fungal colonies on media and microscopic appearance. The course also identifies sources of infection and associated diseases. This course is appropriate for laboratory professionals and students in clinical laboratory science programs who want to increase their understanding of mycology including microscopic and colony appearance and isolate identification.

Objectives

  • Identify hyaline mold isolates by observing the appearance of the colony on agar plates and through microscopic appearance.
  • Discuss various sources of fungal infections and the diseases that are associated with hyaline and dematiaceous molds.
  • Define these terms that apply to fungi and are used to identify specific species: sporulation, conidia, conidiophore, hyphae, phialide.
  • Identify dematiaceous molds by observing characteristic structures and their rate of growth.
  • Identify the common environmental sources (natural habitats) of certain hyaline and dematiaceous molds.
  • Discuss some of the types of diseases associated with opportunistic infections by some of the hyaline and dematiaceous molds.

Course Outline

  • Introduction
    • Introduction
    • Clinical Classifications
    • Pathogens vs. Opportunists
    • Morphological Classifications
    • Those fungi that attack the tissues and organ systems are called:
  • Definitions and terms
    • Nomenclature
    • Structures
    • Diseases and Clinical Conditions
    • A slow-growing subcutaneous lesion on an extremity that can eventually cause bone deformity is called:
  • Hyaline Molds
    • Hyaline Molds
    • The Mucorales (Former Zygomycetes)
    • Microscopic Remarks About the Mucorales (Zygomycetes)
    • The Dermatophytes
    • Diagnosis and Identification of Dermatophytes
    • The Opportunistic Mycoses Caused by Other Hyaline Molds
    • Diagnosis and Identification of Opportunistic Mycoses Caused by Other Hyaline Molds
    • Other Notes - Hyaline Molds That Appear Similar to the Mold Phases of Obligate Pathogens
    • Match each hyaline mold from the drop-down list to its corresponding colony and microscopic description. The mold colonies are illustrated in the image on the right.
    • Match each hyaline mold from the drop-down list to its corresponding microscopic and colony description. The microscopic appearance of the molds are illustrated in the image on the right.
    • Match each hyaline mold from the drop-down list to its corresponding colony and microscopic description. The mold colonies are illustrated in the image on the right.
    • Match each of the names of the fungi listed in the left column with its most likely associated disease listed in the right column.
    • Match each of the names of the hyaline molds listed with the environmental conditions or natural objects with which it is most likely associated.
    • Match the names of each of the species of hyaline molds listed with the appropriate category.
    • Match the names of each of the species of hyaline molds listed with the appropriate category.
    • Match the names of each of the species of hyaline molds listed with the appropriate taxonomic category.
    • Match the names of each of the fungi listed below into the appropriate category indicating the classification of infection with which it is most commonly associated.
    • The microscopic features shown in this image is of a fungus commonly associated with:
    • Based on the structures observed in this image, the most probable species of the fungus recovered from an induced sputum specimen is:
    • Illustrated in this image is a "green lawn" colony of Gliocladium species. What is the other hyaline mold that produces this type of colony?
    • The fungus illustrated in this image was recovered from one induced sputum specimen from a 74-year-old man with chronic obstructive pulmonary disease (COPD). This isolate is most likely:
    • The dermatophytic fungus shown in this image was recovered from a ringworm lesion of the skin on the back of the hand of an 8-year-old boy. What is the most likely place this fungus originated?
    • An Aspergillus species was recovered from a sputum specimen of a patient with X-ray evidence of fungal pneumonia. Microscopic examination did not permit a species identification. A small amount of vegetative mycelium was removed and a direct mount was prepared. The features indicated by the red arrows in this image are associated with which Aspergillus species?
    • What is the identification of the hyaline mold shown in this image?
    • The differentiation between Aspergillus species and Scedosporium species may be difficult when only hyphal elements are observed in stained tissue sections. It is important to obtain a culture to make this differentiation when possible because Scedosporium species, in contrast to Aspergillus species, tend to be resistant to:
    • A dermatophyte that produces thin-walled, two or three-celled macroconidia, and no microconidia, most likely belongs to which genus?
    • The bare fruiting heads shown here, characteristic of Aspergillus niger, demonstrate a spherical vesicle with phialides positioned around the entire circumference of the surface. What is the other Aspergillus species that also sporulates circumferentially?
    • A dull white fungus, turning mouse gray on maturity, was recovered from material aspirated from a bone cyst in the upper femur. Based on the microscopic appearance as seen in a lactophenol blue mount of a portion of the colony, what is the most likely identification?
    • The "birds on a fence" arrangement of uniform-sized, tear-shaped microconidia is characteristic of:
    • The image demonstrates the fruiting heads of Trichoderma species. Note the single, long, tapered phialides (arrow), extending laterally from either side of the hyphae, one of the key identifying features of this fungus. What is another hyaline mold that produces long tapered phialides?
    • Illustrated here is a single conidium of Microsporum canis. Note that the hilar cell appears fractured (shorter red arrow), where it was released from the stolon. Macroconidia having this so-called "break-away" cell are termed:
    • The hyaline saprobic fungus that has microscopic features similar to the mold form of Histoplasma capsulatum is:
    • The hyaline saprobic fungus that has microscopic features similar to the mold form of Coccidioides immitis is:
    • The most helpful feature in differentiating the Mucorales (former Zygomycetes) from the other hyaline molds in the clinical mycology laboratory is:
  • Dematiaceous Molds
    • Dematiaceous Molds with Clinical Significance
    • Dematiaceous Molds with Clinical Significance, continued
    • Diagnosis and Identification of Slow-Growing Molds
    • Diagnosis and Identification of Fast-Growing Molds
    • Other Diagnostic Methods for Dematiaceous Molds
    • Match each of the names of the fungal species listed with the corresponding identifying structures illustrated in the images:
    • Match the names of each of the fungal species listed in the drop-down box with the corresponding identifying structures shown in the images:
    • Presumptive identification of the four genera of slower-growing pathogenic dematiaceous molds can be made by observing specific types of conidiation. Match the names of the species of dematiaceous pathogenic fungi with the corresponding microscopic features illustrated in the images:
    • Match the name of each dematiaceous fungus listed in the drop-down box with its most likely disease.
    • Match the name of each fungal species listed with its most likely corresponding morphologic features.
    • Match the name of each fungal species listed in the drop-down box with its most likely corresponding morphologic feature.
    • Match the names of each of the fungi listed with its appropriate category.
    • Match the names of each of the fungi listed with its appropriate category depending upon whether the multi-celled macroconidia are divided by both longitudinal and transverse septa (dictyospores); or, are divided by only transverse septa.
    • Match the names of each of the fungi listed with its appropriate category indicating the degree of pathogenicity.
    • The fungal species most likely associated with the granulomatous infection seen in this image, illustrating segmented, dark brown-staining grains with a giant cell is:
    • The infrequently encountered mold that is represented by this image begins as a gray-white colony that blackens with maturity as the hyphae become darkened and single, globose, black conidia are produced. This fungus can be identified as:
    • The multi-celled conidia of this dematiaceous mold are divided into cells by what are called distosepta (pseudosepta), indicating that the individual cells are surrounded by a sac-like wall that is distinct from the outer cell wall of the conidium. The identification of this mold is:
    • The oval or curved multi-celled, dark-staining macroconidia divided by transverse septa only is characteristic of:
    • What is the type of sporulation of the dematiaceous mold that is shown in this image called?
    • Of the following dematiaceous fungi, the black, suede-like colony illustrated here, reaching no larger than the size of a dime after 7 days incubation, can most likely be identified as:
    • The dematiaceous colony illustrated here grew to a diameter of 3 - 4 cm in 5 days. The dematiaceous fungus that can be ruled out is:
    • The dematiaceous fungus that may produce both acrotheca and rhinocladiella types of sporulation is:
    • The black yeast colony illustrated in this photograph may represent any of the following dematiaceous molds except:
    • The chain of conidia illustrated in this photomicrograph, with the deep-staining truncated bases, are called annelloconidia, and are most characteristic of:
    • In this image are observed several background dematiaceous hyphae within which is seen a long, flask-shaped, tapered phialide (arrow) that has a flat saucer-like terminus. This feature is most characteristic of:
    • The disease with which the dematiaceous fungus illustrated in this image is most likely associated is:
    • The dematiaceous conidium shown in this image was obtained from a tiny portion of dark colony that grew to maturity in six days. Spores incubated in a saline mount for four hours developed germ tubes from both terminal cells. These features observed confirm the identification of:
    • The chief microscopic feature possessed by Ulocladium species by which it can be differentiated from the close look-alike Stemphylium species is:
  • References
    • References

Additional Information

Level of Instruction: Intermediate to advanced
Intended Audience: Microbiologists, medical laboratory scientists, medical laboratory technicians, and medical laboratory students.
Author Information: 
Elmer W. Koneman, MD, received his graduate degree from the University of Colorado School of Medicine in Denver, Colorado, and until his recent passing, was a Professor Emeritus at their Department of Pathology. He was the author of numerous journal articles and books, including Color Atlas and Textbook of Diagnostic Microbiology, 7th Edition, 2017. 
Margaret Reinhart MS, MT(ASCP) is the MLS Program Director and Senior lecturer in Biological Sciences at the University of the Sciences in Philadelphia PA where she teaches hematology, clinical immunology, parasitology, and other related courses. She is also an adjunct instructor in Hematology at Pennsylvania Hospital, Philadelphia PA. She holds a Masters Degree in Biology and in Health Care Administration.
Reviewer Information: Dr. Julie Ann West is certified by the American Society for Clinical Pathology (ASCP) as a Medical Laboratory Scientist (MLS) and as a Specialist in Microbiology (SM). In addition, Dr. West has earned a PhD in Public Health - Infectious Disease Epidemiology - and is Certified in Public Health (CPH) by the National Board of Public Health Examiners. Dr. West is experienced as a Technical Specialist, Safety Officer, Educator, and Lead in the Veterans Administration Healthcare System, and has prior experience as an Administrative Laboratory Director.
Course Description: This course describes and identifies hyaline and dematiaceous fungi. Many photomicrographs are used to assist with the recognition of organisms in culture and microscopically.