Opportunistic and Deep Mycoses

Coccidioides immitis  (Southwest USA)

• Located in desert soil
• Characteristic structures
• In the environment:  Arthroconidia
• In the body:  Sphereules are pathognomonic

Blastomyces dermatitidis  (north central and southeast USA)

• Associated with water

Lymphocutaneous Sporotrichosis

Mucocutaneous mycoses:  candida and dermatophytosis (get inflammatory response)

• Candida albicans
• Primary cutaneous candidiasis
• Mucocutaneous candidiasis

Candidiasis

• Wide range of infections
• Candida albicans is the most virulent species
• Candida spp. are common organisms of the skin, GI and UG tracts.
• Candidiasis is a disease of compromised hosts.

Mucocutaneous (T CELL IMPAIRMENT)

• Systems affected:
• GI tract, skin, vagina
• Onychomycosis
• Keratitis
• Symptoms:  Odynophagia, stridor, etc.
• Diagnosis: white pseudomembranous plaques with hyphae, pseudohyphae, and budding yeast.
• Groups at risk
• HIV patients
• Diabetics
• Pregnancy
• Age
• Antibiotics
• Steroids

Chronic mucocutaneous candidiasis – autoimmune polyendocrinopathy candidosis ectodermal dystrophy

• Inherited disorder of CMI to candida along with polyendocrinopathies
• Intractable candida infection of the mucocutaneous areas
• Concurrent adrenal insufficiency and hypoparathyroidism
• Type I diabetes
• Hypothryroidism
• Hypogonadism
• Ectodermal dystrophy

Deeply invasive candidiasis (think CANCER)

• Systems affected/ symptoms and signs:
• Candidemia
• Endocarditis – organism is sticky
• Hepatosplenomegaly
• Acute, shocklike syndrome
• Renal dysfunction

At risk groups:  

• Altered barriers
• Neutropenia
• Transplant
• Hemodialysis
• Pathogenesis
• Adherence and colonization
• Penetration through mucosal barriers and angioinvasions/access through catheters
• Hematogenous spread
• Replication yields necrosis +/- abscess with budding yeast and hyphae
• Look at the fundus!  Candida goes to the eyes!

Virulence factors of Candida

• Surface receptors
• Cell wall is an immune modulator
• Hydrolytic enzymes – e.g. acid protease, phospholipase
• Host mimicry – e.g. C3D receptor
• Dimorphism – makes it hardy!
• Germ tube + species.

Superficial:  

• Fungus confined to the stratum corneum or distal portions of hair
• Tinea versicolor:  Malassezia furfur
• Pigmentation changes due to fungal effect on melanocytes
• Can cause folliculitis
• Can cause fungemia in neonates with indwelling vascular catheters receiving total nutrition with lipids.
• Malassezia furfur is a lipophilic yeast and it requires fatty acids to grow.