Lecture 5

FUNGI

General Features

• Eukaryotic, omnipresent, non-vascular, mostly non-motile organisms.
• Heterotrophic, mostly saprophytic.
• Cell wall made of chitin and glucans.
• Cell membrane contains ergosterol.
• Unicellular and multicellular forms are present.
• Reproduce sexually, asexually, or both (dimorphic) via spores.
• Optimum growth temperature:
  • Saprophytes: $20-30°C$
  • Parasitic fungi: $30-37°C$
• Grows best in acidic environments.
• Estimated 1.5 million fungi globally; only about 300 species infect humans.
• Macroscopic forms are present.

Growth

• Two main morphological forms:
  • Vegetative (unicellular or multicellular)
  • Reproductive
• Dimorphic fungi exist as both unicellular and multicellular forms depending on temperature (thermal dimorphism).
• Vegetative form: unicellular or multicellular thallus.
• Reproductive form: multicellular.
• Unicellular fungi: yeasts.
• Multicellular fungi: molds.
• Multicellular fungi form:
  • Hyphae (septate/non-septate)
  • Mycelium
  • Thallus

Reproduction

• Two main fungi groups:
  • Perfect fungi (both sexual and asexual reproduction)
  • Imperfect fungi (only asexual reproduction)
• Asexual reproduction:
  • Spore formation and dispersal
  • Mycelium fragmentation, budding
• Asexual spores:
  • Sporangiospores
  • Conidia
  • Chlamydospores
  • Blastoconidia
  • Arthrospores
• Sexual reproduction:
  • Two mating types:
    • Homothallic
    • Heterothallic
• Three main steps:
  • Plasmogamy: union of cytoplasms
  • Karyogamy: fusion of haploid nuclei
  • Meiosis: generation of different types of mating gametes
• Sexual spores:
  • Ascospores
  • Basidiospores
  • Zygospores
  • Oospores

Fungal Diseases

Mycoses

• Fungal infections caused by fungi in normal skin microbiota or opportunistic pathogens in immunocompromised patients.
• Based on site of infection:
  • Cutaneous mycoses
  • Subcutaneous mycoses
  • Systemic mycoses

Cutaneous Mycoses

• Superficial fungal infections affecting the skin, nails, hair, and mucous membrane.
• Based on the type of fungal infection:
  • Dermatophytic
  • Candidiasis
  • Tinea versicolor/pityriasis versicolor
• Living tissues are not affected.
• Pathological changes occur due to the presence of infectious agents.
• Common symptoms:
  • Red, swollen skin
  • Discolored, cracked, thick nails
  • White patches in throat and/or mouth

Dermatophytes / Ringworm

• Common cause of cutaneous mycoses.
• Caused by filamentous fungal molds utilizing keratin protein for growth.
• Pathogens are collectively referred to as ‘dermatophytes’.
• Infections caused by dermatophytes collectively named ‘tinea’.
• Three genera of dermatophytes:
  • Trichophyton
  • Epidermophyton
  • Microsporum
• Mode of transmission: direct skin-to-skin contact.

Trichophyton

• Genus of fungi including causative agents of ringworm, athlete’s foot, and jock itch infections
• Found in humans, animals, soil, and river sediments.
• Largest of the three dermatophyte genera with 22 species.
• Produce both microconidia and macroconidia
  • Microconidia: spherical or clavate.
  • Macroconidia (rare): phragmsoseptate aluericonidia, clavate.

Microsporum

• Genus of fungi including 15 parasitic species
  • Microconidia: clavate, $4-7 μm × 2.5 μm$ in size
  • Macroconidia: fusiform or spindle-shaped, thick-walled, phragmoseptate aleurioconidia, $35-125 μm$ (sometimes up to $160 μm$) × $7-20 μm$ with 4 to 15 septa, spiny, sperulate, or pitted outer cell wall

Epidermophyton Sabouraud

• 2 species of human parasites
• No microconidia
  • Macroconidia: club-shaped, broadly round apex, $8-15 μm × 6-10 μm$ with >5 septa, present singly or in clusters

Characteristic Features of Ringworm Infections

• Ringworm: itchy, circular rash with clearer skin in the middle

Tinea Corporis

• Infectious agent/s

  • Trichophyton rubrum
  • Trichophyton mentagrophytes
  • Microsporum audouinii

• Site of infection

  • torso
  • arms
  • legs
  • neck

• Symptoms

  • initially - solitary circular red patch with raised scaly leading edge
  • Ringworm
  • Multiple asymmetrical lesions

• Diagnosis of tinea corporis:

  • Dermoscopy: examination of the skin using dermatoscopy
  • Microscopic examination: skin scrapings with a potassium hydroxide (KOH) preparation; septate and branching long narrow hyphae.
  • Culture: Sabourad dextrose agar (1% glucose, 4% mycological peptone agar, water)

• Treatment and management of tinea corporis:

  • Topical treatment/s:
    • Clotrimazole: 1% cream/ointment/solution applied topically twice daily
    • Ketoconazole: 2% cream/shampoo/gel/foam applied once daily
    • Miconazole: 2% cream/ointment/solution/lotion/powder applied twice daily
    • Naftifine: 1% cream, applied once daily or 1% or 2% gel twice daily
    • Terbinafine: 1% cream/gel/spray solution once or twice daily
  • Oral treatment/s:
    • Terbinafine: 250 mg orally once daily for two weeks
    • Itraconazole: 100 mg once daily for 2 weeks or 200 mg once daily for one week
    • Fluconazole: 150 to 200 mg once weekly or 50 to 100 mg/day for 2 to 4 weeks
    • Griseofulvin: 500 to 1000 mg once daily for 2 to 4 weeks
  • Prevention and management:
    • Avoid sharing personal items
    • Immediately shower after engaging in contact sports
    • Avoid prolong wearing of tight fitting clothes
    • Use only personal items when using communal showers

Tinea Capitis

• Agents
  • Trichophyton rubrum, Trichophyton Sudanese, Trichophyton tonsurans, Trichophyton verrucous, Microsporum canis (most common in New Zealand, Europe, and Asia)
• Site of infection & mode of infection
  • Scalp
  • Scalp hair
• Type of infection
  • Inflammatory – results in kerion and scarring alopecia patchy alopecia with associated pustules or folliculitis, kerion, favus
    • Endothrix infection – invades the hair shaft and grows within it. Cuticle isn’t destroyed
    • Ectothrix infection – grows within the hair follicle and covers the hair surface. Cuticle is destroyed
  • Non-inflammatory – do not result in alopecia
    • Grey patch, black dots, diffuse scale
  • Favus infection – chronic infection characterized by clusters of hyphae at the base of the hairs, with air spaces in the hair shafts
• Diagnosis of tinea capitis:
  • Wood lamp examination: exposure of hair or skin into a black light emitted by a wood lamp
    • Microsporum species fluoresce blue-green/ yellow green
    • T. schoenleinii fluoresce dull blue
  • Trichoscopy: comma hair, zig-zag hair, corkscrew hair, bar-code like hair
  • Microscopic examination: skin scrapings with a potassium hydroxide (KOH) preparation; presence of spores and hyphae
  • Culture: Sabourad dextrose agar (1% glucose, 4% mycological peptone agar, water)
• Treatment and management of tinea capitis:
  • Topical treatments are ineffective
  • Oral treatment/s:
    • Griseofulvin
    • Terbinafine
    • Itraconazole
    • Fluconazole
    • Antifungal shampoo
  • Prevention and management:
    • General education
    • Avoid sharing personal items
    • Avoid places where children might get infected
    • Wash hands after petting or coming into contact with pets

Tinea Pedis (Athlete’s Foot)

• Agents
  • Trichophyton rubrum, Trichophyton mentagrophytes, T interdigitale, Epidermophyton floccosum
• Site of infection
  • Toes
  • Feet sole and heel
• Type of infection
  • Toe web infection – most common type
    • Affects the skin between 4th and 5th toe
  • Moccasin-type infection – affects bottom of the feet, heels and edges
  • Vesicular-type infection – typically affects the bottom, but can be seen anywhere on the foot
    • Consist of bumps or fluid-filled blisters
  • Ulcerative infection – rarest type
    • Cause ulcerations between toes
• Symptoms
  • Skin colour changes
  • Skin may crack, peel or flake off
  • Sore feet bottoms of feet thickens and cracks
  • Open sores/ ulcerations
• Diagnosis of tinea pedis:
  • Microscopic examination: skin scrapings with a potassium hydroxide (KOH) preparation; presence of spores and hyphae
  • Culture: Sabourad dextrose agar (1% glucose, 4% mycological peptone agar, water)
• Treatment and management of tinea captis:
  • Topical treatment/s:
    • Azoles
    • Allylamines
    • Butenafine
    • Ciclopirox
    • Tolnaftate
  • Oral treatment/s:
    • Terbinafine
    • Itraconazole
    • Fluconazole
    • Griseofulvin
  • Prevention and management:
    • Dry feet and toes meticulously after bathing
    • Avoid wearing occlusive footwear for long periods
    • Thoroughly dry shoes and boots
    • Avoid walking barefoot in communal showers and pools

Tinea Barbae (Barber’s Itch)

• Common infectious agents
  • Trichophyton rubrum
  • Trichophyton verrucosum
  • Trichophyton mentagrophytes
• Rare infectious agents
  • Trichophyton violaceum
  • Trichophyton megninii
  • Microsporum canis
  • Microsporum nanum
  • Mycroscporum gypseum
  • Epidermophyton floccosum
• Site of infection
  • cheeks
  • chin
  • neck
  • upper lip
• Symptoms
  • Red, lumpy rash
  • Kerion
  • No itching
• Treatment and management of tinea barbae:
  • For mild cases: Topical treatments
  • Oral treatment/s:
    • Terbinafine: 125 mg to 250 mg once a day
    • Itraconazole: 100 mg once a day
    • Fluconazole: 200 mg once a day
    • Ketoconazole: 200 to 400 mg a day
  • Prevention and management:
    • General education
    • Avoid sharing personal items (shaving tools)
    • Treat infected animals with antifungal cream
    • Wash hands after coming into contact with livestock

Tinea Cruris (Jock Itch)

• Common infectious agents
  • Trichophyton rubrum
  • Epidermophyton floccosum
• Site of infection
  • Groin
  • Pubic region
  • Inner thighs
• Symptoms
  • Spreading rash in the crease of the groin and moves down the upper thigh and buttocks
  • Rash with a clear center
  • Rash is either fully or partially ring-shaped bordered with small blisters
• Diagnosis of tinea cruris:
  • Microscopic examination: skin scrapings with a potassium hydroxide (KOH) preparation; presence of spores and hyphae
  • Culture: Sabourad dextrose agar (1% glucose, 4% mycological peptone agar, water)
• Skin biopsy – Periodic Acid Schiff (PAS) stain
• Treatment of tinea captis
  • Topical treatment/s
    • azoles
    • allylamines
  • Oral treatment/s
    • fluconazole
    • itraconazole
    • terbinafine
• Prevention and management
  • avoid sharing personal items
  • avoid wearing tight fitting clothes, wear breathable cotton lose underwear
  • thoroughly wash and dry clothes
  • thoroughly wash and dry pubic and groin area

Tinea Unguium (Onychomycosis)

• Agents

  • Trichophyton rubrum, T mentagrophytes, Epidermophyton floccosum

• Site of infection

  • Toenails
  • Fingernails

• Type of infection

  • Lateral onychomycosis: infection occurs on the side of the toenail
  • Proximal onychomycosis: infection occurs close to the center of the toenail. Infects the toe bed as well
  • Distal onycholysis: infection occurs towards the side from the center of the toenail. Infects the toe bed as well
  • Superficial white onychomycosis: only infects the toenail on the upper side
  • Subungual hyperkeratosis: stratum corneum under the nail plate gets thickened (hyperkeratosis)

• Symptoms

  • White/ opaque streaks on the side of the toenail
  • Half-moon shaped yellow spots
  • Lifting and crumbling of the edge of the toenail
  • Flaky white patches and pits appear on the top of the nail plate
  • Accumulation of dead skin cells under the nail plate

• Diagnosis of Tinea unguium:

  • Dermoscopy
  • Microscopic examination: skin scrapings with a potassium hydroxide (KOH) preparation; presence of spores and hyphae
  • Culture: Sabourad dextrose agar (1% glucose, 4% mycological peptone agar, water)
  • Histopathology: Periodic Acid Schiff (PAS) stained nail clippings and subungual debris

• Treatment and management of tinea unguium:

  • Topical treatment/s:
    • Ciclopirox 8% lacquer
    • Tavabarole 5% solution
    • Efinaconazole 10% solution
    • Amorolfine 5% lacquer
  • Oral treatment/s:
    • Fluconazole
    • Itraconazole
    • Terbinafine
    • Posaconazole
  • Prevention and management:
    • Avoid unhygienic cosmetic nail practices
    • Avoid walking barefoot in communal swimming pools
    • Keep feet cool and dry
    • Using proper diabetic medication
    • Keep nails clean and trimmed

Candidiasis

• Cause cutaneous mycoses known as ‘cutaneous candidiasis’
• Caused by Candida sp.
• Common causative agent: Candida albicans
• Opportunistic pathogens
• Affects different areas of the body
• Mode of transmission: direct skin-to-skin contact, sexual contact

Candida Albicans

• Small, oval, unicellular yeast
• Asexual reproduction: budding
• Polymorphic fungi: yeast and pseudohyphae form
• Can also form true hyphae
• Considered Gram-positive
  • On SDA agar: Creamy, pasty colonies, smooth, distinct smell
  • On blood agar: white, creamy colored colonies with foot-like extensions

Oral/Thrush Candidiasis

• Infection of the oral cavity due to the overgrowth of normal oral microbiota
• Common causative agent: Candida albicans
• Non-common causative agents: Candida glabrata, Candida tropicalis, Candida kruesi, Candida guillermondii, Candida lusitaniae, Candida parapsilosis, Candida pseudotropicalis, and Candida stellatoidea
• Causes creamy white lesions, usually on the tongue or inner cheeks
• Other symptoms:
  • Soreness/ burning sensation in the tongue
  • Cotton-like sensation
  • Dry, cracked skin at the corners of the mouth
  • Swallowing difficulty
  • Loss of taste

Angular Cheilitis

• Common, non-contagious, inflammatory condition affecting the corners of the mouth
• Common causative agent: Candida albicans
• Caused due to various risk factors
• Symptoms:
  • Painful and bleeding cracks
  • Redness
  • Maceration
  • Swelling

Vulvovaginal Candidiasis

• Inflammatory condition affecting the vagina and the vulva
• Common causative agent: Candida albicans
• Affects ~75% of reproductive-age women
• Various risk factors
• Symptoms:
  • Itching, soreness and burning discomfort in the vagina and vulva
  • Burning sensation during urinating
  • Dense white curd or cottage cheese-like vaginal discharge
  • Bright red rash affecting inner and outer parts of the vulva
  • Vulval oedema

Cyclic Vulvovaginitis

• Recurrent burning and itching of the vulva and/or vagina that recurs at the same phase of the menstrual cycle
• Various risk factors
• Symptoms:
  • Itching, irritation and burning discomfort just before and during menstruation
  • Aggravating pain during and after sexual intercourse
  • Minimal vaginal discharge
  • Vulval oedema

Balanitis

• Inflammation of the glans penis (head of the penis)
• Affects ~3-11% of males within their lifetime
• Various risk factors
• Symptoms:
  • Itching, irritation and burning around the penis head
  • Thick, white, foul-smelling discharge
  • Blisters
  • Dysuria

Candidal Intertrigo

• Superficial skin-fold infection
• Affects skin folds below the breasts or under the abdomen, armpits and groin web spaces between the fingers or toes
• Common causative agent: Candida albicans
• Various risk factors
• Symptoms:
  • Bleeding, raw skin
  • Reddish/ brown rash
  • Cracked/ crusty skin

Napkin Dermatitis/ Diaper Rash

• Inflammatory reaction of the skin of the perineal and perianal areas (diaper area)
• Affects babies that mostly wear traditional nappies/diapers
• Common causative agent: Candida albicans
• Various risk factors
• Symptoms:
  • Inflamed skin in the diaper area — buttocks, thighs and genitals
  • Itchy, tender skin in the diaper area
  • Discomfort, fussiness or crying
  • Sores

Paronychia

• inflammation of the skin around a finger or toenail

• Can be acute of chronic

• Causative agent - Candida albicans

• Various risk factors

• Symptoms

  • tender, painful and swelled are around the nail
  • warm and red skin
  • pus under the skin

• Diagnosis of candidiasis:

  • Microscopic examination: skin scrapings/swabs with a potassium hydroxide (KOH) preparation; presence of spores and hyphae
  • Culture: blood agar culture
  • Histopathology: Periodic Acid Schiff (PAS) stained skin swabs/ scrapings, Gomori methenamine silver stain (GMS) skin swabs/ scrapings

• Oral thrush

  • nystatin
  • miconazole
  • clotrimazole
  • fluconazole (for severe and esophagul infections)

• angular cheilitis

  • azole creams
  • fluconazole (for severe cases)

• vulvovaginal candidiasis

  • Clotrimazole 1% cream 5 g intravaginally daily for 7–14 days
  • Clotrimazole 2% cream 5 g intravaginally daily for 3 days
  • Miconazole 2% cream 5 g intravaginally daily for 7 days
  • Miconazole 4% cream 5 g intravaginally daily for 3 days
  • Miconazole 100 mg vaginal suppository one suppository daily for 7 days
  • Fluconazole 150 mg orally in a single dose (for severe cases)

• Balanitis

  • clotrimazole 1% twice daily
  • miconazole 1% twice daily
  • nystatin cream (alternative)
  • Fluconazole 150 mg orally in a single dose (for severe cases)
  • Candidal intertrigo - clotrimazole, fluconazole (for severe cases)

• Diaper rash

  • hydrocortisone cream twice daily for 1-2weeks
  • Clotrimazole once or twice a day
  • ketoconazole once or twice a day
  • aloe vera gel/cream

• Paranoychia azole creams, antiseptic creams

• Prevention and management

  • general and patient awareness
  • maintaining good health practices

Pityriasis Versicolor

• Common yeast infection resulting in flaky, discoloured patches on the shoulders, back and upper chest

• Causative agents: fungal species of the genus Malassezia

• Common causative agents: M. globosa, M. sympodialis and M. furfur

• Mostly affect teens and young adults

• Common in hot humid climates

• Mostly asymptomatic, but can be mildly itchy

• Non-contagious

• Diagnosis of pityriasis versicolor:

  • Wood lamp examination: blue/green appearance
  • Microscopic examination: skin scrapings with a potassium hydroxide (KOH) preparation; spaghetti and meatballs appearance
  • Histopathology: Periodic Acid Schiff (PAS) stained skin biopsies

• Treatment of pityriasis versicolor

  • Topical treatment/s
    • selenium sulfide shampoo
    • topical azole creams/ shampoo
    • terbinafine gel
  • Oral treatment/s
    • fluconazole
    • itraconazole
  • Prevention and management
    • vigorous exercising after taking medications
    • avoid bathing for a few hours
    • reapplication of topical creams/gels/shampoo during hot humid climates

Subcutaneous Mycoses

• Chronic infectious diseases of the skin and underlying structures caused by a diverse group of fungi and other microorganisms.
• Considered as a Neglected Tropical disease (NTD).
• Main fungal subcutaneous mycoses:
  • Sporotrichosis
  • Chromoblastomycosis
  • Mycetoma
  • Lobomycosis
  • Subcutaneous zygomycosis

Systemic Mycoses

• Fungal infections affecting the internal organs.
• Mainly affects immunocompromised people (opportunistic mycoses).
• Healthy individuals may also be infected (primary/ endemic mycoses).
• Caused by dimorphic fungi.
• Mode of entry: inhalation of air-borne spores via the lungs.
• Can be spread via the bloodstream causing multiple organ failure.
• 95% of cases are asymptomatic and self-limited.

Primary Systemic Mycoses

• Infections of the internal organs of immunocompetent humans
• Caused by dimorphic fungi
• Four main types are present
  • Blastomycosis
  • Coccidioidomycosis
  • Histoplasmolysis
  • Paracoccidioidomycosis

Blastomycosis

• Chronic granulomatous infection

• Causative agent: Blastomyces dermatitidis

• Inhalation of conidial spores

• Primary infection: pulmonary blastomycosis

  • Cough, fever, malaise, and weight loss

• Secondary infection:

  • Cutaneous blastomycosis: painless lesions on face, upper limbs, neck, and scalp (in >70% of patients)
  • Osteoarticular blastomycosis: causes subcutaneous abscesses

• Diagnosis of blastomycosis

  • Specimens: Skin scrapings, sputum and bronchial washings, cerebrospinal fluid, pleural fluid and blood, bone marrow, urine and tissue biopsies
  • Microscopic examination: Skin scrapings and exudates and body fluids (sediment after centrifugation) with a potassium hydroxide (KOH) and Parker ink preparation
  • Histopathology: Periodic Acid Schiff (PAS) stained skin biopsies
  • Culture: Sabouraud's dextrose agar and Brain heart infusion agar supplemented with 5% sheep blood
  • Antibody detection tests: complement fixation test, immunodiffusion using purified B. dermatitidis A antigen

• Treatment of blastomycosis

  • if left untreated can be lethal
  • Amphotericin B
  • for CNS infections; liposomal Amphotericin B

Coccidioidomycosis

• Primarily a respiratory infection
• Causative agent: Coccidioides immitis
• Inhalation of arthrospores
• Primary infection: benign and transient chest infection (60% of patients), chronic pulmonary infection - fever, pleuritic chest pain, cough, malaise, headache, myalgia, night sweats and loss of appetite
• Secondary infection: systemic disease involving the meninges, bones, joints and subcutaneous and cutaneous tissues, causes granulomatous lesions on skin, bones, meninges and joints
• Diagnosis of Coccidioidomycosis
  • Specimens: Skin scrapings, sputum and bronchial washings, cerebrospinal fluid, pleural fluid and blood, bone marrow, urine and tissue biopsies
  • Microscopic examination: Skin scrapings and exudates and body fluids (sediment after centrifugation) with a potassium hydroxide (KOH) and Parker ink preparation
  • Histopathology: Periodic Acid Schiff (PAS) stained skin biopsies
  • Culture – Sabouraud's dextrose agar and Brain heart infusion agar supplemented with 5% sheep blood
  • Antibody detection tests complement fixation test, immunodiffusion
• Treatment of blastomycosis
  • Amphotericin B
  • Anoralazole derivatives

Histoplasmosis

• intracellular mycotic infection of the reticuloendothelial system
• Causative agent: Histoplasma capsulatum
• Inhalation of microcondia
  • 95% of patients: inapparent, subclinical or benign, symptoms - fever, chills, headache, muscle aches, fatigue, cough and chest discomfort
  • 5% of patients: chronic progressive lung disease, chronic cutaneous or systemic disease or an acute fulminating fatal systemic disease
    • Symptoms - enlarged spleen and liver, gastrointestinal bleeding, lip and mouth ulcerations, decreased white and red blood cells leading to bone marrow failure, meningitis, lesions, endocarditis
• All stages of the infection mimics tuberculosis
• Diagnosis of Coccidioidomycosis
  • Specimens: Skin scrapings, sputum and bronchial washings, cerebrospinal fluid, pleural fluid and blood, bone marrow, urine and tissue biopsies
  • Microscopic examination: Skin scrapings and exudates and body fluids (sediment after centrifugation) with a potassium hydroxide (KOH) and Parker ink preparation
  • Histopathology: Periodic Acid Schiff (PAS) stained or GMS stained skin biopsies
  • Culture – Sabouraud's dextrose agar and Brain heart infusion agar supplemented with 5% sheep blood
  • Antibody detection tests – complement fixation test, immunodiffusion
• Treatment of blastomycosis - Amphotericin B (only for severe cases)

Paracoccidioidomycosis

• Chronic granulomatous disease
• Causative agent: Paracoccidioides brasiliensis
• Inhalation of conidial spores
• Primary infection: chronic pulmonary infection - cough, fever, night sweats, malaise and weight loss
• Secondary infection
  • Mucocutaneous paracoccidioidomycosis - painful ulcerated lesions on the gum, lips, tongue or palate, perforation of the palate or nasal septum, cutaneous lesions often appear on the face around the mouth and nose
  • Lymphonodular paracoccidioidomycosi - Cervical and submandibular chains, lymph nodes may progress to form abscesses with draining sinuses
  • Disseminated paracoccidioidomycosis - lesions of the small or large intestine, hepatic lesions, adrenal gland destruction, osteomyelitis, arthritis, endophthalmitis and meningoencephalitis or focal cerebral lesions
• Diagnosis of Coccidioidomycosis
  • Specimens - Skin scrapings, sputum and bronchial washings, cerebrospinal fluid, pleural fluid and blood, bone marrow, urine and tissue biopsies
  • Microscopic examination - Skin scrapings and exudates and body fluids (sediment after centrifugation) with a potassium hydroxide (KOH) and Parker ink preparation
  • Histopathology – Periodic Acid Schiff (PAS) stained or GMS stained skin biopsies
  • Culture – Sabouraud's dextrose agar and Brain heart infusion agar supplemented with 5% sheep blood
• Treatment of blastomycosis - Amphotericin B, areazole derivatives, sulfonamides

Opportunistic Mycoses

• Infections of the internal organs of immunocompromised humans
• Infected with AIDS, aggressive cancer and post-transplantation chemotherapy, use of antibiotics, cytotoxins, immunosuppressives, corticosteroids and other macro disruptive procedures result in lowered resistance of the host

Mycotoxins

• Naturally occurring toxins produced by certain molds (fungi) and can be found in food.
• Low-molecular-weight natural products produced as secondary metabolites by filamentous fungi.
• Can cause disease and death in human beings and other vertebrates.
• Molds grow on a variety of different crops and foods including cereals, nuts, spices, dried fruits, apples and coffee beans, often under warm and humid conditions
• Currently, FDA focuses mainly on aflatoxins, deoxynivalenol, fumonisins, patulin and ochratoxin A
• aflatoxins – produced by certain aspergillus sp.
  • food contamination usually involves aflatoxins B1, B2, G1, and G2 for crops and M1 for milk
  • found in peanuts, corn, tree nuts such as Brazil nuts and pistachios, and some small grains such as rice and milk of cows that feed on contaminated crops
  • regular consumption can lead to increased risk of liver cancer, cause birth defects, and lead to kidney and immune system problems
• Deoxynivalenol – produced by certain Fusarium molds
  • grows on wheat, corn, oats, barley, and other grains under normal weather conditions, but especially in cool, wet conditions
  • cause vomiting, nausea, and other symptoms
• Fumonisins – produced by certain Fusarium molds
  • commonly infect corn but also sometimes infect other grains like wheat, cause illnesses in animals
• Patulin – produced by Penicillium, Aspergillus and Byssochylamys molds
  • grow on fruit, grains, and cheese, cause vomiting, nausea, and damage the DNA
• Ochratoxin A – produced by certain Penicillium and Aspergillus molds
  • found in contaminated grains, such as wheat, rye, oat, and barley, and in coffee, grapes and wine