MIP A56: Medical Mycology

Question 1

What is sick building syndrome?

Answer 1

Presents with fatigue, headache, and difficulty concentrating associated with living/ working in mouldy environments

Question 2

True or False: Any fungus that can grow at 37 C is a potential pathogen in a immunosuppressed host

Answer 2

True

Question 3

What are the different groups of fungi based on type of interaction with the host?

Answer 3

Primary (true) pathogens (can cause desease in immunocompetant persons); Opportunistic pathogens (restricted to debilitated or immunosuppressed persons); Commensal (normally benign but can become oppurtunits); Saprobes (limited/ negligible disease causing ability)

Question 4

What are the two general courses a fungal infection can take?

Answer 4

1) Slowly progressive chronic infections in immunocompetant patients 2) Life-threatening acute infections in compromised patients

Question 5

What are the two major ways we come into contact with fungi?

Answer 5

Environmental (incidental); or from our normal Flora

Question 6

What are the routes of fungal entry into the human body?

Answer 6

Inhalation, Skin and mucosal surfaces, penetration of the skin,

Question 7

True or False: There is no TLR that has affinity for fungal cell wall components.

Answer 7

False- TLRs play an important role in the innate microbial recognition of fungi

Question 8

Expression of what class of molecules allows fungi to bind to host/cells and tissue?

Answer 8

Adhesins

Question 9

What are the ways by which fungi can interfere with PAMP-PRR?

Answer 9

Shielding immunostim. PAMPs by the cell wall; MOdulate inflammatory signals; different morphotypes

Question 10

Besides interfering with the PAMP-PRR system, what are the other ways that fungi evade host recognition?

Answer 10

Persiting in the intracellular environment, Interference with phagocytosis, complement evasions

Question 11

How do fungi cause damage to the host?

Answer 11

Secretion of damaging enzymes (phospholipases, catalases, keratinases), induction of cytokines–> inflammation; moulds secrete mycotoxins (aflatoxin)

Question 12

What fungal virulence factors are more common in eukaryotic pathogens but not prokaryotes?

Answer 12

Ability to switch cell type, morphological forms (dimorphism), and cell wall barriers

Question 13

What fungal virulent attributes allow for invasion/evasion and survival?

Answer 13

Thermotolerance, acquisition of nutrients, adaptation to stress (differential gene expression)

Question 14

What are superficial mycoses?

Answer 14

Superficial, cosmetic infections of the skin (stratum corneum) or hair shaft

Question 15

What is the most common superficial mycosis in the US?

Answer 15

Tinea (pityriasis) versicolor (Liver spots) caused by Malassezia spp.

Question 16

What are the causative organisms that cause cutaneous mycoses?

Answer 16

Dermatophytes and Candida

Question 17

What are the common cutaneous mycoses?

Answer 17

Athlete’s foot, ringworm, jock itch

Question 18

What is the name of the category of diseases caused by a fungus?

Answer 18

Mycoses

Question 19

True or False: Fungal cell walls contain peptidoglycan.

Answer 19

False

Question 20

Why has the incidence of fungal infections increased?

Answer 20

Increased immunocompromised and elderly population and modern medical techniques

Question 21

What characteristic separates fungal cells from animal cells?

Answer 21

Fungal cells are non motile

Question 22

What characteristic separates fungal cells from plant cells?

Answer 22

Fungi are heterophlic

Question 23

What is chitin?

Answer 23

A structural polymer of N-acetylglucosamine that is part of fungal cell walls

Question 24

What are the two growth forms fungi can take?

Answer 24

Yeast or mold

Question 25

What is the difference between dimorphic and polymorphic fungi?

Answer 25

Dimorphic fungi grow as mold or yeasts during specific stages of their life cycles, while polymorphic fungi have multiple growth forms but they do not correlate to a distinct stage of the life cycle

Question 26

How do yeast forms of fungi reproduce?

Answer 26

Asexual budding or fission

Question 27

What are hyphae?

Answer 27

Filamentous, cylindrical cells of mold fungi (one cell=hypha)

Question 28

What is a mycelium?

Answer 28

A mass of hyphae

Question 29

What is the morphologic appearance of aspergillus fumigatus hyphae?

Answer 29

The hyphae branch at 45 degree angles

Question 30

What is sporulation?

Answer 30

Propagation of fungi through formation of propagules that disperse in water or air

Question 31

What is conidiogenesis?

Answer 31

The method of sporulation

Question 32

True or False: Fungal spores can be either sexual or asexual

Answer 32

True

Question 33

What does calcofluor stain?

Answer 33

Chitin

Question 34

What are mycotoxicoses?

Answer 34

Poisoning by food products contaminated by toxins which were produced from the grain substrate by fungi

Question 35

What is mycetismus?

Answer 35

The ingestion of preformed toxin (neurotoxins) (mushroom poisoning)

Question 36

What is typically the route of infection for subcutaneous mycoses?

Answer 36

Traumatic implantation of environmental fungi, normally in the lower extremities

Question 37

What is the most frequent subcutaneous fungal infection worldwide?

Answer 37

Sporotrichosis (sporothrixi schenckii)

Question 38

What is the morphology of sporotrichosis?

Answer 38

Mold in the environment but yeast at 37 C ; cigar shaped yeast

Question 39

How is chronic mycotic infection of cutaneous or subcutaneous tissues and adjacent lymphatics characterized?

Answer 39

Granulamatous skin ulcer followed by regional lymphadenopathy

Question 40

Where does extracutaneous sporotrichosis manifest?

Answer 40

In joints

Question 41

What is black mold?

Answer 41

Over 100 species of evironmental mold with melanin pigmint in the cell walls

Question 42

What is chromoblastomycosis?

Answer 42

Cutaneous and subcutaneous mycosis with chronic granulomas especially feet and legs caused by black molds

Question 43

What are the three clinical presentations of phaeohyphomycosis?

Answer 43

Cutaneous-subcutaneous cyst; Cerebral abscess & other deep seated sites; Fungal sinusitis- allergic

Question 44

What is penicilliosis and what is its clinical presentation?

Answer 44

A dimorphic fungal AIDS opportunistic infection that presents with pulmonary symptoms is most AIDS pts and skin dissemination of molluscum-like lesions

Question 45

What is the most common fungal agent for life threatening infections? Which species is most common in almost all disease manifestations?

Answer 45

Candidiasis; albicans

Question 46

What is the most common opportunistic fungal pathogen?

Answer 46

Candida

Question 47

What is candida's morphology?

Answer 47

Polymorphic: yeast, pseudohyphae, and true hyphae

Question 48

How is Candidiasis likely to manifest in a patient with a CD4+ T cell defect?

Answer 48

Oral candidiasis (thrush)

Question 49

How is Candidiasis likely to manifest in a patient with neutropenia?

Answer 49

Systemic candidiasis

Question 50

What does thrush look like?

Answer 50

Creamy, white curd-like plaques on oral mucosal surfaces

Question 51

What is mucormycosis?

Answer 51

Fungal infection of the sinuses, brain, or lungs primarily associated with immunosuppressed patients

Question 52

Why is mucomycosis potentially fatal?

Answer 52

The hyphae can colonize vessels leading to the formation of blood clots

Question 53

What is the most common fungi isolated from contact lens cases?

Answer 53

Fusarium keratitis