Candidiasis: Fungal Infection
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Questions and Answers

What is the main pathogen responsible for candidiasis?

Candida albicans

Which of the following are considered predisposing factors for candidiasis? (Select all that apply)

  • High levels of physical activity
  • Age over 80
  • Prolonged use of antibiotics (correct)
  • Nutritional deficiencies (correct)
  • Oral candidiasis is often localized but can extend to the pharynx or lungs.

    True

    What are the common sites affected by candidiasis?

    <p>Oral cavity, skin, gastrointestinal tract, vagina, urinary tract, lungs</p> Signup and view all the answers

    What type of lesions are characteristic of pseudomembranous candidiasis?

    <p>Soft, white, slightly elevated plaques</p> Signup and view all the answers

    Which of the following antifungal agents is used for the treatment of oral candidiasis? (Select all that apply)

    <p>Nystatin</p> Signup and view all the answers

    What is the optimal growth temperature for Candida species?

    <p>25–37°C</p> Signup and view all the answers

    What is the clinical manifestation of erythematous candidiasis?

    <p>Red or erythematous lesions</p> Signup and view all the answers

    Candida-associated lesions can include conditions such as denture stomatitis.

    <p>True</p> Signup and view all the answers

    Which group of people is at higher risk for developing oral candidiasis? (Select all that apply)

    <p>Patients receiving corticosteroids</p> Signup and view all the answers

    What is a common indicator that oral candidiasis is occurring?

    <p>Presence of white plaques in the oral cavity</p> Signup and view all the answers

    Chronic mucocutaneous candidiasis requires standard antifungal therapies for treatment.

    <p>False</p> Signup and view all the answers

    What are the common treatments for severe forms of histoplasmosis?

    <p>Amphotericin B</p> Signup and view all the answers

    Crytococcosis is an opportunistic infection increasingly seen in immunosuppressed individuals.

    <p>True</p> Signup and view all the answers

    What is the preferred staining method to visualize Cryptococcus organisms?

    <p>India Ink Staining</p> Signup and view all the answers

    Study Notes

    Candidiasis

    General Information

    • Definition: A common fungal infection affecting humans, particularly as an opportunistic infection in immunosuppressed individuals
    • Primary form: Rare; usually secondary to underlying conditions
    • Affected areas: Skin, mucous membranes, nails, internal organs
    • Alternative names: Moniliasis, thrush, candidosis, le muguet ("lily of the valley")

    Causative Agents

    • Main pathogen: Candida albicans
    • Other species: C. tropicalis, C. parapsilosis, C. stellatoidea, C. krusei, C. guilliermondii, C. dubliniensis, C. rugosa, C. viswanathii, and C. glabrata

    Morphology and Reproduction

    • Forms: Pseudohyphae, yeast, chlamydospore
    • Reproduction: Asexual budding; forms pseudohyphae
    • Growth conditions: Optimal at 25–37°C

    Normal Habitat

    • Presence: Oral cavity, gastrointestinal tract, vagina of healthy individuals
    • Transition to pathogenic form: Requires favorable conditions for yeast to hyphae transformation

    Pathogenesis

    • Invasion mechanisms:
      • Secretion of degrading enzymes (e.g., aspartic proteases)
      • Epithelial endocytosis (hyphae engulfed by epithelial cells)

    Epidemiology

    • Opportunistic nature: Most common opportunistic infection globally
    • Increased incidence: Due to antibiotic use, immunosuppressive drugs (corticosteroids, cytotoxic drugs)
    • High-risk groups:
      • Leukemia, lymphoma, or other tumor patients
      • HIV-infected individuals (over 90% develop oral candidiasis at some stage)

    Clinical Manifestations

    • Common sites: Oral cavity, skin, gastrointestinal tract, vagina, urinary tract, lungs
    • Oral candidiasis: Usually localized but can extend to the pharynx or lungs, potentially fatal
    • Increased vaginal colonization: Linked to diabetes, pregnancy, oral contraceptive agents

    Predisposing Factors for Candidiasis

    • Acute and chronic diseases:
      • Tuberculosis
      • Diabetes mellitus
      • Anemia
    • Endocrine disorders:
      • Myxedema
      • Hypoparathyroidism
      • Addison disease
    • Immunodeficiency:
      • AIDS
    • Nutritional deficiencies:
      • Iron deficiency
      • Vitamin A deficiency
      • Vitamin B6 deficiency
    • Prolonged hospitalization:
      • Chronic illness
      • Debilitating diseases
    • Medications:
      • Prolonged use of antibiotics
      • Corticosteroids
      • Cytotoxic drugs
    • Radiation therapy
    • Medical devices:
      • Intravenous tubes
      • Catheters
      • Heart valves
    • Lifestyle factors:
      • Poorly maintained dentures
      • Heavy smoking
    • Demographic factors:
      • Old age
      • Infancy
      • Pregnancy
    • Xerostomia:
      • Absence of protective antifungal proteins like histatins and calprotectin in saliva

    Immunopathogenesis of Candidiasis

    • Specific and nonspecific factors:
      • Anticandidal and antiadherence factors: Play a major role in development
      • Salivary IgA: Affects adherence of Candida to mucosal cells
      • Immune cells:
        • T cells and neutrophils prevent and clear infection
        • Exhibit phagocytic and candidacidal activities involving myeloperoxidase, superoxide, and cationic proteins
      • Other factors (less significant):
        • Complement
        • Transferrin
        • Lactoferrin
        • Vitamins A and C
        • Serum antibody

    Clinical Features of Oral Candidiasis

    • Pseudomembranous candidiasis (thrush):
      • Soft, white, slightly elevated plaques
      • Common locations: Buccal mucosa, tongue, palate, gingiva, floor of the mouth
      • Composition of plaques: Tangled masses of fungal hyphae, intermingled desquamated epithelium, keratin, fibrin, necrotic debris, leukocytes, and bacteria
    • Erythematous candidiasis (antibiotic sore mouth):
      • Red or erythematous lesions
      • Diffuse borders, unlike the sharp, well-demarcated borders of erythroplakia
      • Can occur at any site in the oral cavity
      • Consistently painful, distinguishing it from other forms of oral candidiasis
    • Chronic hyperplastic candidiasis (candidal leucoplakia):
      • Firm, white persistent plaques resembling leukoplakia
      • Commonly located on the lips, tongue, and cheeks
      • Lesions may be homogeneous or speckled (nodular) and persist for a long time
      • Histopathology shows invasion of the epithelial surface by hyphae at the superficial layer
    • Denture stomatitis (chronic atrophic candidiasis):
      • Diffuse erythema and edema of the denture-bearing area
      • Often associated with angular cheilitis
      • The mandibular mucosa is rarely affected

    Chronic Mucocutaneous Candidiasis

    • Definition: A group of different forms of candidiasis with multiple common features, categorized into various entities
    • Oral manifestations: Occur in numerous forms of candidiasis, including chronic mucocutaneous candidiasis
    • General characteristics:
      • Chronic involvement of skin, scalp, nails, and mucous membranes by Candida infection
      • Patients exhibit varying immune system abnormalities:
        • Impaired cell-mediated immunity
        • Isolated IgA deficiency
        • Reduced serum candidacidal activity
      • Usually resistant to common forms of treatment

    Types of Chronic Mucocutaneous Candidiasis

    • Chronic familial mucocutaneous candidiasis:
      • Inheritance: Likely autosomal recessive
      • Onset: Typically before the age of 5
      • Gender distribution: Equal in males and females
      • Clinical features: Oral lesions are common in affected children
    • Chronic localized mucocutaneous candidiasis:
      • Onset: Early in life, without genetic transmission
      • Clinical features:
        • Widespread skin involvement with granulomatous and horny masses on the face and scalp
        • Increased incidence of other fungal and bacterial infections
        • Oral lesions are common primary sites
        • Nail involvement is frequently observed
    • Chronic diffuse mucocutaneous candidiasis:
      • Onset: Typically late
      • Clinical features:
        • Extensive raised crusty sheets affecting limbs, groin, face, scalp, shoulders, mouth, and nails
        • No familial history
        • Patients usually have no other abnormalities
    • Candidiasis-endocrinopathy syndrome:
      • Inheritance: Genetically transmitted
      • Clinical features:
        • Candida infection of skin, scalp, nails, and mucous membranes, particularly the oral cavity
        • Associated with endocrine disorders like hypoadrenalism (Addison disease), hypoparathyroidism, hypothyroidism, ovarian insufficiency, or diabetes mellitus
        • Endocrine manifestations may appear several years after the initial thrush in children### Diagnosis of Aspergillus Infections
    • Microscopical examination: direct examination of smear stained with potassium hydroxide (KOH), Parker ink, calcofluor, or Gram stain
    • Aspergillus hyphae appear septate and dichotomously branched
    • PAS stain is effective for demonstrating hyphae morphology
    • Culture: clinical specimens cultured in Sabouraud dextrose agar media
    • Colonies may exhibit varying colors: white, yellow, yellow-brown, brown, black, or green
    • Immunodiffusion test: used to detect antibodies specific to Aspergillus species

    Treatment of Aspergillus Infections

    • Primary treatment: Amphotericin B administered along with surgical debridement
    • Combination therapy options:
      • Amphotericin B + Caspofungin: effective combination therapy
      • Amphotericin B + Flucytosine or Itraconazole: also proven useful in treatment

    Histoplasmosis (Darling Disease)

    Causal Organism and Transmission

    • Causal organism: Histoplasma capsulatum
    • Acquired through inhalation of fungal spores found in bird excreta

    Clinical Classification

    • Acute primary pulmonary: initial infection primarily affecting the lungs
    • Chronic pulmonary: persistent lung infection
    • Cutaneous and mucocutaneous: involvement of skin and mucous membranes
    • Disseminated: spreads beyond lungs to extrapulmonary sites, including the oral cavity; more common in older, debilitated, or immunocompromised patients

    Pathogenesis

    • Fungus multiplies in monocytes and macrophages, causing necrotic areas favorable for growth
    • Invades bloodstream, leading to metastatic lesions in liver, spleen, and lymph nodes

    Oral Manifestations

    • Often the presenting complaint in disseminated histoplasmosis cases
    • Nodular, ulcerative, or vegetative lesions on buccal mucosa, gingiva, tongue, or lips
    • Ulcerated areas covered by a gray, indurated membrane with raised borders similar to carcinoma

    Diagnosis

    • Direct smear examination using calcofluor white, Giemsa, or Wright stains reveals small oval-shaped yeast cells within immune cells
    • Fungal culture on Sabouraud dextrose agar, immunological testing, and animal pathogenicity assays assist in diagnosis

    Histological Features

    • Granulomatous infection primarily affecting the reticuloendothelial system
    • Organisms predominantly found within phagocytic cells
    • Tiny intracellular structures measuring slightly over 1 µm in diameter
    • Distinctive oval-shaped yeasts with narrow budding, typically 2–4 µm in size

    Treatment

    • Spontaneous resolution in mild cases: pulmonary histoplasmosis often resolves without specific treatment in mild cases
    • Severe forms treatment: severe forms of the disease typically require treatment with amphotericin B

    Cryptococcosis (Torulosis, European Blastomycosis)

    Causative Agents and Transmission

    • Causative agents: Cryptococcus neoformans (Torula histolytica) and Cryptococcus bacillispora
    • Transmission: likely occurs via inhalation of airborne microorganisms
    • Opportunistic nature: increasingly seen in immunosuppressed individuals

    Clinical Features

    • Incidence and geographic distribution: recent increase in incidence; tropical climate of the Indian subcontinent favors C.neoformans growth
    • Primary infection sites: initial evidence often seen in skin lesions
    • Skin lesions: appearance: multiple brown papules that ulcerate; clinical presentation: non-specific
    • Demographic predilection: slight preference for middle-aged males
    • Systemic involvement: lung lesions, meningeal lesions, bone and bone marrow involvement

    Oral Manifestations

    • Occurrence: occasional cases reported, typically in patients with concurrent visceral or cutaneous lesions
    • Clinical presentation: oral lesions manifest as nonspecific single or multiple ulcers
    • Diagnostic challenge: resemblance to other conditions requires careful differentiation

    Histological Features

    • Diagnosis methods: India ink staining, culture
    • Microscopic appearance: Gram-positive, budding, yeast-like cell with an extremely thick, gelatinous capsule that stains intensely with PAS stain
    • Size: measures 5–20 µm in diameter
    • Tissue sections: presents as a small organism with a large clear halo, termed "tissue microcyst"
    • Tissue reaction: granulomatous reaction of the tuberculoid type

    Treatment

    • Treatment with Amphotericin B: demonstrates excellent efficacy in managing Cryptococcosis
    • Prognosis: highly variable based on the sites of infection

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    Description

    This quiz covers the general information and causative agents of candidiasis, a common fungal infection affecting humans, particularly in immunosuppressed individuals.

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