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a;lskdjf > 4 - Fungal Diseases > Flashcards

4 - Fungal Diseases Flashcards

1
Q

Types of fungal infections

A
  • Non-invasive cutaneous mycoses
  • Invasive cutaneous mycoses
  • Systemic mycoses
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2
Q

Non-invasive cutaneous mycoses

A

o Parasitize only the cornified components of the skin
o It’s rare when one of these fungi invade vascularized living tissue (dermatomycoses, or superficial infections)
o The noninvasive cutaneous mycoses are extremely common, accounting for more than 90% of all fungus related patient - doctor visits
o Result in major expense of time and money with a high morbidity, but few deaths or no deaths result

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3
Q

Invasive cutaneous mycoses

A

o Result from direct penetration of viable epidermis, dermis, subcutaneous and deeper tissues
o Spread is by contiguous extension

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4
Q

Systemic mycoses

A

o Almost always begin as invasive pulmonary infections that may spread by contiguity within the lung and adjacent tissue, but more typically through the bloodstream
o Transported as intracellular pathogens within the blood-borne phagocytic cells

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5
Q

Host resistance factors

A
  • The host parasite struggle is influenced by factors from both.
  • Little is known in reference to fungal virulence (pathogenic potential)
  • More is known about the host’s struggle
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6
Q

Two courses of fungal infections

A
  • Self-limited course

- Chronic or progressive course

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7
Q

Self-limited course

A

o Acute ringworm, sporotrichosis) characterized by brisk inflammation, focal and characterized by a self-limited course

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8
Q

Chronic or progressive course

A

o Chronic mucocutaneous candidiasis, mycetoma) characterized by an infection that is met with an inadequate host resistance produce less inflammatory lesions that usually spread locally or disseminate and typically have a chronic and progressive course

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9
Q

Non-invasive cutaneous infections

A
  • The term tinea refers to all noninvasive cutaneous mycoses except those caused by candida species, which are termed candidiasis
  • THE LATIN TERM e.g., (Pedis, capitis, etc.) - Refers to anatomical location
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10
Q

Subdivisions of non-invasive cutaneous infections

A
  • The noninvasive mycoses are subdivided into three subgroups based on pathogenic potential, and degree of host reaction:
    o Superficial infections
    o Dermatophyte infections
    o Candidiasis
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11
Q

Superficial infections

A
  • Tinea versicolor, tinea nigra palmaris, and piedra are skin conditions that proliferate only in the statum corneum
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12
Q

Tinea versicolor

A

Pityrosporon orbicular
- Grows in sebaceous gland-rich areas of skin

Signs and symptoms

  • Hypo- or hyperpigmented macules that fail to tan with sun exposure
  • Mild itching may be exacerbated with sweating or bathing
  • Lesions may appear on the forearms, face, scalp, fingers groin, and legs, but the upper torso, neck and proximal upper extremities are more commonly affected. The palms, soles, and mucous membranes are never affected
Differential diagnosis (DIFFICULT TO DISTINGUISH)
-	Papulosquamous, seborrheic dermatitis, pityriasis rosacea, chronic dermatitides

Treatment

  • Antifungal shampoo’s: Selenium disulfide, Zinc pyrithione
  • Topical creams: Ketoconazole
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13
Q

Tinea nigra palmaris

A

C. Werneckii

  • C. Werneckii invades the stratum corneum of the palms and soles
  • There is slow lateral spread within the stratum corneum
  • Little or no inflammatory reaction, but slight acanthosis and hyperkeratosis
  • Uncommon, but has a greater incidence in the south/eastern coastal states

Signs and symptoms

  • Asymptomatic, but single brown to black macule on palms or soles
  • The infected area is usually sharply marginated, macular, and non-scaly
  • There may be one focus or several large irregular shaped macules

Differential diagnosis
- Junctional nevi and melanoma, incipient trauma and hemorrhage, silver nitrate, ammoniated mercury, and other organic dyes, systemic diseases (Addison’s)

Treatment

  • Keratolytic agents: (Whitfield’s ointment, Keralyte gel, or 40% urea)
  • Itraconazole, terbinafine; Imidazole creams (lotrimin, monostat-derm)
  • Thiabendazoles, removal of lesion by scraping
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14
Q

Piedra

A

Piedraia hortae, Trichosporon cutaneum
- A condition of the hair shaft characterized by firm, irregular nodules composed of elements from the infecting organism

Signs and symptoms

  • Hair nodule may be black: the causative organism (Piedraia hortai)
  • Hair nodule may be white: the causative organism (Trichosporon cutaneum)
  • White Piedra is typically found in the southern United States
  • Black Piedra will typically be found in tropical environments

Treatment

  • REMOVE THE HAIR – shave or cut hair in infected area
  • Black piedra  use oral terbinafine
  • White piedra  use topical antifungals (ciclopirox olamine, selenium sulfide, chlorahexadine solution)
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15
Q

Dermatophyte infections

A
  • The various species of Trichophyton, epidermophyton, and microsporum have the ability to infect all cornified components of the skin, including the hair and nails
  • Pathogenesis
    o Once the skin is colonized, the dermatophyte hyphae penetrate into the stratum corneum and migrate deep until the granular layer is reached
    o Spreading continues laterally
    o Clinical manifestations and course of the infection is based host’s immune response to the infecting organism and its exocellular antigens
  • Most common dermatophyte  Tinea pedis
  • Other dermatophytes  Tinea unguium, Tinea cruris, Tinea corporis, Tinea manuum, Tinea capitis, Allergic dermatophytids
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16
Q

Tinea pedis

A

MOST PREVALENT FUNGAL INFECTION

  • Note that NO form of tinea is common before pre-pubertal years
  • No geographic restrictions, but less common in areas with no footwear
  • Three types  (1) interdigital, (2) vesicular, (3) hyperkeratotic erythrodermic, moccasin, chronic papulosquamous, ulcerative
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17
Q

Tinea pedis - lab findings, treatment

A

Laboratory findings  Characteristics on Sabouraud agar

  • Trichophyton rubrum  White cotton; red
  • Trichophyton mentagrophytes  White cotton, or cream to tan powder
  • Epidermophyton floccosum  Fuzzy; tan, yellow, green

KOH examination
- Septated hyphae

Treatment
- Topical or oral antifungals

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18
Q

Interdigital tinea pedis

A

T. Rubrum or T. Mentagrophytes

  • Typically does not spread beyond the intertriginous confines and is distinct in its presentation and natural course
  • May either have a type a or type b course

Differential diagnosis
- Nonspecific dermatitis or bacterial intertrigo

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19
Q

Vesicular tinea pedis

A

May be caused by either of the dermatophytes

  • May occur anywhere on the foot
  • Presentation is intensely inflammatory w/ vesicles, and bullae in foci or clusters
  • Follows a type a course

Differential diagnosis
- Cellulitus, pyococcal infection, eczema, and contact dermatitis

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20
Q

Chronic papulosquamous tinea pedis (moccasin)

A

T. Rubrum

  • Tends to be minimally inflammatory, characterized by dull, erythema, dryness, scaling, and hyperkeratosis affecting the entire plantar skin of both feet in a moccasin distribution
  • Follows a type b course

Differential diagnosis
- Psoriasis, lichen planus, icthyosis, graft vs. host

21
Q

Cutaneous candidiasis - general

A
  • Has the greatest pathogenic potential of the noninvasive cutaneous pathogens
  • Invasion of the viable epidermis, dermis and mucocutaneous membranes is possible
  • Strong predilection for intertriginous areas of the inguinal folds, intergluteal cleft, axillae, inframammary folds, and umbilicus
22
Q

Cutaneous candidiasis - Diabetes/immunosuppression

A
  • Diabetes is a frequent clinical association, as is the use of antibiotics, corticosteroids, and immunosuppressive medications.
  • Immunosuppressive disorders
  • Primary factors are those that affect occlusion and moisture in intertriginous areas
  • Colonization is from the host’s own gastrointestinal or mucosal sources
23
Q

Cutaneous candidiasis - signs/symptoms

A
  • Burning, stinging, and itching occurs in the intertriginous areas of the affected body part
  • Typical acute changes are beefy red, scalded skin with irregular margin and satellite pustules
  • A chronic, scaling form may occasionally be seen (dermatophytosis)
24
Q

Cutaneous candidiasis - laboratory findings, differential diagnosis and treatment

A

Laboratory findings

  • Removal of the roof of a pustule reveals mycelial elements within the stratum corneum
  • Mycologic culture of a pustule reveals a creamy mucoid colony within 48-72 hours

Differential diagnosis
- Nonspecific intertrigo, allergic contact dermatitis, psoriatic intertrigo, irritant dermatitis, pityriasis rosea, Hailey-Hailey disease

Treatment

  • Topical nystatin, imidazole antifungals, oral ketoconazole
  • Non-specific measures to remove the moisture in the area
25
Q

Oral candidiasis

A

Thrush

  • White patches affecting the tongue, buccal mucosa, palate, and oropharynx
  • Mucosa bleeds easily when patches are scraped gently with a tongue blade
26
Q

Angular chelitis

A
  • Appear as erythematous fissures on the corners of the mouth
  • Can be mistaken for vitamin deficiencies, contact dermatitis
27
Q

Invasive cutaneous mycoses

A

Infections that begin at a point of focus within the skin, secondary to trauma or a foreign object might have penetrated the skin

  • Chromoblastomycosis
  • Mycetoma
  • Sporotrichosis
  • Mucormycosis
28
Q

Chromoblastomycosis

A

(Foneseca, Phialophora, Cladosporium)

  • The fungi grows as filamentous, saprophytic organisms in the soil, where they extract nutrients from decaying vegetation
  • Present within the viable layers of the epidermis and dermis
  • There may be contiguous local spread within the skin, and involvement of the entire extremity or generalized infection is occasionally encountered
29
Q

Chromoblastomycosis - Signs and symptoms

A
  • The earliest changes are itching, warty papule, or perhaps an ulcer
  • Warty sores follow trauma
  • May progress to a foul smelling plaque, palm size
  • Involvement of a single extremity without sinus tract formation
  • The infection slowly enlarges over months-years (the plaque may present with black dots within the verrucous lesion)
  • Progression of the lesion leads to scarring
  • Many patients develop secondary bacterial infections
  • Centrifugal spread, atrophy, and scarring in the central area is suggestive of chromomycosis
  • Elephantiasis of the lower extremity may result if fibrosis and obstruction of the lymph channels
30
Q

Chromoblastomycosis - lab findings

A

KOH examination:
o Specimen should be collected from a black dot or microabscess within a verrucous nodule
o Brown branching hyphae are presumptive evidence of chromomycosis

CONFIRMATORY TESTS - mycologic culture, biopsy ***

31
Q

Chromoblastomycosis - treatmetn

A
  • Nonspecific measures include bedrest, elevation of the affected part
  • Antibiotic therapy for secondary infection
  • Specific therapeutic measures may include surgical excision of affected tissue
  • Prescription therapy may include flucytosine, thiabendazole, ketoconazole and topical heat
32
Q

Maduromycosis (mycetoma)

A

Allescheria boydii, Madurella, Phialophora

  • Mycetoma’s caused by true fungi , have traditionally been referred to as maduromycosis or eumycotic mycetoma
  • Mycetoma is caused by bacteria which are referred to as actinomycotic
  • Occurs in the tropics and sub-tropics, organism is present within the soil
33
Q

Maduromycosis (mycetoma) - signs and symptoms, complications

A
  • Initially there is a painless, rather indolent slowly necrotic process occurring in the affected area
  • ***Triad associated with infection:
    o Sinus tracts draining to the skin surface
    o Discharge fluid contains granules ranging in color (white/tan/red/black)
    o A nodular tumorous, fibrotic swelling

Complications and sequelae
- Destructive fibrosis, tumefaction, and swelling to the point of elephantiasis may render the extremity non-functional, and necessitate amputation

34
Q

Maduromycosis (mycetoma) - laboratory findings

A
  • Diagnosis depends upon clinical and laboratory findings:
    o Grain color, size, texture - helpful
    o Fungal, aerobic, anaerobic cultures are essential
    o A deep tissue biopsy necessary for histopathology
35
Q

Maduromycosis (mycetoma) - treatment

A
  • Specific therapeutic measures depend upon the organism (eumycotic, or actinomycotic)
  • Actinomycotic infections: can successfully be treated with Bactrim or dapsone
  • Eumycotic infections: treated with oral antifungals in conjunction with debridement tends to be unsuccessful - amputation is often required
36
Q

Mucormyosis

A

Rhizopus, Mucor, etc.

  • Mucormycosis, zygomycosis, and phycomycosis are the clinical terms applied to invasive infections caused by fungi belonging to genera (rhizopus, Mucor, etc.)
  • Very uncommon, skin involvement is even less common
  • Opportunistic infection (patient has serious medical problems, often complicated by immunosuppression)
37
Q

Sporothrichosis

A

Sporothrix schenckii

  • The causative organism is (Sporothrix schenckii) Tends to infect individuals who have contact with soil, or decaying vegetative products
  • Infection typically follows trauma and usually causes a painful ulcerated nodule
  • Chancriform: tender, sometimes painful nodule on the finger or hand, accompanied by lymphadenopathy
  • Fixed cutaneous plaques and ulcers may be tender and painful, and occasionally in verrucous lesions pruritus may be present
  • The skeletal system may also be affected, leading to destructive arthritis, tenosynovitis and lesions of the bone.
  • Other clinical manifestations (pulmonary manifestations, eye involvement, nervous system involvement, and other organ involvement as a true systemic infection.)
38
Q

Sporothrichosis lab findings and treatmetn

A

Laboratory findings

  • The organism may be cultured on any mycologic medium with saboraud’s dextrose agar
  • An organism may be identified by fluorescent antibody staining techniques

Treatment
- Chancriform sporotrichosis
o Saturated solution of potassium iodide (4-6 weeks past clinical cure)
o Amphotericin B, flucytosine, and ketoconazole
- Fixed cutaneous sporotrichosis
o Standard t(x) for musculoskeletal, and for systemic manifestations Amphotericin B is used

39
Q

Systemic mycoses

A
  • The systemic mycoses essentially all begin in the lung
  • Cutaneous manifestations are a result of allergic manifestations or hematogenous dissemination into the skin
  • The systemic mycoses include:
    o Coccidioidomycosis
    o Blastomycosis
    o Paracoccidioidomycosis
    o Cryptococcosis
    o Histoplasmosis
40
Q

Coccidioidomycosis

A

Coccidioides Immitis, Coccidioides posadasii
- Airborne mold present in dry areas of the world

Signs and symptoms

  • Primary pulmonary infection, influenza like symptoms (cough, fever, night sweats, chest pain, myalgias and fatigue)
  • The patient may also develop erythema multiforme, or erythema nodosum

Treatment
- Ketoconazole, Itraconazole, Fluconazole, Amphotericin B

41
Q

Blastomycosis

A

Blastomyces dermatitidis

    • Called North American Blastomycosis Chicago disease, Gilchrist’s disease
  • Uncommon disease thought to be endemic to Ohio and Mississippi River Valley
  • Usually affects men aged 30-50

Signs and symptoms
- Presenting symptoms skin involvement or coughing the typical lesion is a verrucous papule, nodule or plaque on the face, neck or upper torso

Treatment
- Amphotericin B, Ketoconazole, Potassium iodide

42
Q

Paracoccidioidomycosis

A

General

  • Known as South American Blastomcosis
  • Organism is found in the soil
  • Primary pulmonary infection is usually mild

Signs and symptoms

  • Most common presentation is oropharyngeal ulceration
  • Significant pain, distress, and distress are secondary to papules, nodules and verrucous plaques, massive cervical lymphadenopathy may lead to painful abscesses and draining sinuses.

Treatment
- Sulfonamides and amphotericin B, ketoconazole

43
Q

Cryptococcosis

A

Cryptococcus neoformans

    • Organism is an encapsulated bud yeast
  • Found worldwide, infection can occur at any age, but more typical in adults
  • Occurs in the immunocompromised individual

Signs and symptoms

  • A variety of morphological lesions have been seen: including abscesses, tumor-like masses, draining sinuses, panniculitis, papules, nodules, and ulcerations
  • May mimic a bacterial cellulitis, or molluscum contagiosum

Treatment
- Amphotericin B, oral flucytosine, fluconazole

44
Q

Histoplasmosis

A

General

  • Organism is found in soil worldwide, usually in soil with high concentrations of bird and bat feces
  • Dermatological manifestations are rare in the US, but tend to be more frequent in Latin America (dissemination to the skin may be present as a necrotic ulceration)

Signs and symptoms

  • Primarily a pulmonary infection, skin lesions are uncommon
  • With chronic ulcerative lesions of the mucosal surface being, by far, the most frequent mucocutaneous manifestation
45
Q

6 Subspecies, 7 classified clinical manifestations of histoplasmosis

A
  • Histoplasmosis infection
  • Asymptomatic (self-limited)
  • Acute pulmonary
  • Histoplasmosis disease
  • Diffuse acute pulmonary
  • Chronic pulmonary
  • Disseminated (in AIDS or in non-AIDS)
46
Q

Laboratory findings and treatment for histoplasmosis

A

Laboratory findings

  • Direct examination  Yeast cells in urine, sputum and CSF, or blood in AIDS pts.
  • Culture  white, tan, light brown colonies on Sabouraud agar

Treatment
- Amphotericin B, Itraconazole/fluconazole, AmBisome

47
Q

Aspergillus

A

General

  • A mold found in decaying organic matter
  • Other than candida, it is one of the MOST COMMON invasive fungal infections
  • The route of infection is secondary to the inhalation of spores
  • Patient populations and antifungal prophylaxis have contributed to a change in the spectrum of invasive fungal pathogens
  • There has been a significant increase in infection and resistance to current therapy as a result

Lungs
- Aspergillus primarily affects the LUNGS, but there are 4 different pathological syndromes

48
Q

Aspergillus syndromes

A

4 pathological syndromes
- Allergic bronchopulmonary aspergillosis (ABPA)
o A fumigatus colonization in conjunction with asthma or cystic fibrosis
- Aspergilloma (a fungus ball) mycetoma
o Develops in the parenchyma, pre-existing cavity may be secondary to TB, emphysema, sarcoidosis
- Chronic necrotizing pulmonary aspergillosis
o Usually associated with some form of immunosuppression,
o Usually unrecognized and can develop a cavitary pulmonary infiltate
- Invasive aspergillosis
o This is an often fatal infection in the immunocompromised
o This infectious process is characterized by invasion of blood vessels, resulting in multifocal infiltrates, which are often wedge-shaped, pleural-based, and cavitary. Dissemination to other organs, particularly the central nervous system, may occur

49
Q

Treatmetn for aspergillus

A
  • Invasive aspergillosis and chronic necrotizing aspergillosis
    o Voriconazole is usually first-line therapy
    o Sometimes in combination with other agents such as caspofungin
  • Allergic bronchopulmonary aspergillosis (ABPA)
    o ABPA is a hypersensitivity reaction treated with corticosteroids
    o The addition of oral antifungal therapy (itraconazole) is beneficial
  • Aspergillomas
    o May respond to prolonged oral itraconazole therapy
    o Intracavitary therapy with amphotericin has also been used in a small number of patients

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