Med. Myc. Topic 10 - Subcutaneous Mycoses

Subcutaneous mycoses usually arise from what?

Traumatic implantation

What are the 5 types of subcutaneous mycoses?

Sporotrichosis, Chromoblastomycosis, Phaeohyphomycosis, Lobomycosis, and Mycetoma

What 2 subcutaneous mycoses were discussed in lecture?

Sporotrichosis and Chromoblastomycosis

Most subcutaneous mycoses are rare in the US with the exception of what?

Sporotrichosis

What genera is responsible for causing sporotrichosis?

Sporothrix

What is the name for the overarching group of Sporothrix species?

S. schenckii sensu lato

What are the 4 Sporothrix species primarily responsible for causing sporotrichosis?

S. schenckii sensu stricto, S. globosa, S. brasiliensis, S. mexicana

Sporothrix spp. belong to what phylum and sub-phylum?

Phylum = Ascomycota | Sub-phylum = Pezizomycotina

What is the name for the teleomorph stage of Sporothrix spp.?

Ophiostoma

Sporothrix stands out among other dimorphic fungal pathogens due to the ______ NOT being the primary route of infection and due to having substantial ______ transmittability.

Pulmonary system | Zoonotic

At what temperature does S. schenckii exist as a yeast?

37C

What shape is the yeast of S. schenckii?

Cigar shaped

At what temperature does S. schenckii exist as a mold?

25C

(T/F) S. schenckii hyphae produce both thin-walled clusters of conidia at the end of conidiophores and individual thick-walled, triangular shaped conidia attached directly to hyphae.

True

S. schenckii strains that don’t grow above 35C are associated with _____ _____ while strains that grow best at 37C are associated with ______ _____.

Fixed cutaneous | disseminated infections

What 3 plants is S. schenckii heavily associated with?

Sphagnum moss, rose thorns, and hay

What is the common name for sporotrichosis?

Rose Gardener’s Disease

(T/F) Sporotrichosis can affect anyone regardless of age or gender, what matters is exposer.

True

Sporotrichosis can also be acquired through infected animals. What animal is heavily associated with sporotrichosis?

Cats

What 2 parts of the complement system help defend against sporotrichosis?

C3b and MAC

Adaptive immunity against sporotrichosis is primarily mediated by what type of leukocyte?

T cells

What are the 2 major immune responses and the cytokines they produce?

TH17 = IL-17 | TH1 = IFN-gamma

Once Sporothrix spp. enter the body, what form do they take?

Yeast

What adhesin does Sporothrix spp. use and what receptor does it bind to?

Peptido-rhamnomannan → Fibronectin

What cell wall component of Sporothrix spp. is unique to it?

Rhamnose

What are the other 3 virulence factors that Sporothrix spp. use?

Proteases, siderophores, and melanin

What are the 4 types of sporotrichosis?

Cutaneous & Lymphocutaneous, Pulmonary, Osteoarticular, Disseminated

What form of sporotrichosis is characterized by skin lesions at the site of infection, that may or may not spread to adjacent areas via lymphatic vessels, that slowly grow and eventually ulcerate?

Cutaneous & Lymphocutaneous

What do multiple lesions all over the body away from the initial site of infection indicate?

Hematogenous spread

(T/F) A lesion that remains by itself and doesn’t spread is called a fixed lesion, and it doesn’t usually ulcerate; it is often caused by S. schenckii strains that grow best at temperatures below 35C.

True

What form of sporotrichosis is characterized by a low-grade fever, weight loss, productive cough, and hemoptysis as well as radiographic findings of cavitary lesions in the upper lobe of the lung?

Pulmonary sporotrichosis

What 3 factors contribute to susceptibility to pulmonary sporotrichosis?

Alcoholism, TB, and diabetes

Which form of sporotrichosis is characterized by stiffness and pain in a joint, and radiologic evidence of osteomyelitis?

Osteoarticular sporotrichosis

(T/F) Disseminated sporotrichosis is rare, but primarily occurs in immunocompromised patients such as those with AIDS.

True

Rank the 4 Sporothrix species based on virulence.

1. S. brasiliensis

2. S. schenckii sensu stricto

3. S. globosa

4. S. mexicana

What special stain is used to assist in diagnostic detection of Sporothrix spp.?

Gomori methenamine silver (GMS)

What is the characteristic structure of Sporothrix spp. called when looked at under a histology slide?

Asteroid bodies

Sporothrix spp. cells under histology are called “asteroid bodies” because they have rays or spikes of what?

Antigen-antibody complex

What is the name of the skin test used for presumptive diagnosis of sporotrichosis?

Sporotrichin

What are the 3 main treatment options for cutaneous/lymphocutaneous sporotrichosis?

Potassium Iodide (KI), Itraconazole, heat

How is potassium iodide administered as a therapy for cutaneous/lymphocutaneous sporotrichosis?

SSKI (super saturated potassium iodide)

What treatment is normally administered for osteoarticular sporotrichosis?

Itraconazole

What treatment is normally administered for disseminated sporotrichosis?

AmB (Amphotericin B)

What method has been implemented in attempt to reduce transmission by infected cats, primarily by making them less aggressive?

Castration

What are the 5 main culprits of chromoblastomycosis?

Fonsecaea pedrosoi, Cladophialophora carrionii, Phialophora verrucosa, Rhinocladiella aquaspersa, Exophiala dermatitis

What are the other 4 names for chromoblastomycosis?

“Verrucous Dermatitis”, “Chromomycosis”, “Pedroso’s Disease”, “Fonseca’s Disease”

(T/F) All 5 fungi that cause chromoblastomycosis are melanized.

True

(T/F) The same 5 agents that cause chromoblastomycosis (CBM) can also cause phaeohyphomycosis (PHM).

True

(T/F) CBM is usually seen in immunocompetent individuals while PHM is not.

True

What is the phylum and sub-phylum of the agents of CBM?

Phylum = Ascomycota | Sub-phylum = Pezizomycotina

(T/F) CBM is usually found in adults males, rare in children, but has been reported in animals.

True

What is the name of the distinct form that CBM causing fungi take on during infection that allows them to resist destruction by macrophages and neutrophils?

Sclerotic bodies

What is the major virulence factor of CBM causing fungi?

Melanin

The clusters of lesions caused by CBM is said to look like what?

Florets of cauliflower

What are the 2 ways CBM primarily spreads?

Lymphatic drainage and auto-inoculation

(T/F) CBM causes aesthetic and functional discomfort, but is usually not painful.

True

CBM lesions can become painful and develop a putrescent odor and purulent exudate when what happens?

Secondary infection by bacteria

CBM occasionally can cause blockage of lymph channels and cause what?

Elephantiasis

Where does CBM induced elephantiasis normally affect?

Legs and scrotum

Despite CBM dissemination being rare, it can happen - what fungus is the most common agent of disseminated infections?

F. monophora

Which fungus has been recorded to disseminate to the lungs and brain?

F. pedrosoi

What special stain is used in diagnosis of CBM that stains specifically for melanin?

Fontana-Masson stain

What is structurally unique about the sclerotic bodies of CBM agents?

They have both X and Y axis crosswalls

What are the other 2 names for “sclerotic bodies”?

Medlar and Muriform bodies

What are the 3 classes of therapy for CBM?

Physical, chemical, and combination

What are the 2 types of physical therapy for CBM?

Thermotherapy & Cryosurgery

What is the drug of choice for chemotherapy of CBM?

Itraconazole

What is the combination therapy used to treat CBM?

Cryosurgery + itraconazole