Medical Mycology Overview
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Questions and Answers

Which type of mycoses is primarily associated with systemic infections in patients with weakened immune systems?

  • Systemic and opportunistic mycoses (correct)
  • Subcutaneous mycoses
  • Cutaneous mycoses
  • Superficial mycoses

What is the asexual reproductive structure produced by the transformation of a vegetative yeast or hyphal cell in fungi?

  • Spores
  • Conidia (correct)
  • Hyphae
  • Mycelium

Which of the following fungi is known to cause thrush?

  • Histoplasma capsulatum
  • Coccidioides immitis
  • Blastomyces dermatitidis
  • Candida albicans (correct)

What characteristic is associated with molds as opposed to yeasts?

<p>Fuzzy appearance (D)</p> Signup and view all the answers

The cell wall of fungi serves multiple purposes. Which of the following is NOT a function of the fungal cell wall?

<p>Serves as a nutrient storage site (C)</p> Signup and view all the answers

What is a defining feature of Pityriasis Versicolor?

<p>Caused by the mold genus Malassezia (B)</p> Signup and view all the answers

Which of the following infections is classified under endemic and dimorphic mycoses?

<p>Blastomycosis (B)</p> Signup and view all the answers

Which structure primarily anchors a fungal colony and absorbs nutrients?

<p>Mycelium (D)</p> Signup and view all the answers

What is the most prevalent species of the Rhizopus genus causing mucormycosis?

<p>Rhizopus oryzae (C)</p> Signup and view all the answers

Which condition significantly increases the risk of developing mucormycosis?

<p>Chronic steroid treatment (D)</p> Signup and view all the answers

Which of the following is a common yeast species responsible for candidiasis?

<p>Candida albicans (D)</p> Signup and view all the answers

What type of clinical form is majorly associated with mucormycosis?

<p>Rhinocerebral mucormycosis (A)</p> Signup and view all the answers

What is the primary cause of thrombosis and necrosis in rhinocerebral mucormycosis?

<p>Germination of sporangiospores (A)</p> Signup and view all the answers

Which of the following conditions is NOT a risk factor for mucormycosis?

<p>Recent antibiotic use (B)</p> Signup and view all the answers

Which of the following is NOT a species of the Candida genus?

<p>C. aureus (A)</p> Signup and view all the answers

What structural adaptation do Candida species demonstrate when cultured or in tissue?

<p>Formation of pseudohyphae (C)</p> Signup and view all the answers

Which of the following species is NOT a key dermatophyte responsible for dermatophytosis?

<p>Candida (D)</p> Signup and view all the answers

What is the typical clinical feature of tinea corporis?

<p>Circular patches with an advancing red border and central scaling (C)</p> Signup and view all the answers

Which demographic is most commonly affected by dermatophyte infections?

<p>Athletes and individuals in close contact sports (C)</p> Signup and view all the answers

In which location are lesions of tinea pedis typically found?

<p>Interdigital spaces on the feet (C)</p> Signup and view all the answers

What is the primary mechanism through which dermatophyte infections are acquired?

<p>Contact with contaminated soil, animals, or surfaces (D)</p> Signup and view all the answers

How do dermatophytes respond to the body's temperature?

<p>They are unable to grow at 37°C or in the presence of serum (A)</p> Signup and view all the answers

What clinical feature is associated with tinea capitis?

<p>Circular bald patches with broken hair stubs (D)</p> Signup and view all the answers

What treatment is commonly used for infections caused by Malassezia furfur complex?

<p>Topical or oral antifungal 'azoles' or topical selenium sulfide (B)</p> Signup and view all the answers

What is a unique characteristic of Candida albicans compared to other Candida species?

<p>It produces a germ tube. (C)</p> Signup and view all the answers

What common risk factor is associated with the development of thrush?

<p>Treatment with antibiotics. (D)</p> Signup and view all the answers

Which of the following is NOT a common symptom of vaginal thrush?

<p>Heavy menstrual bleeding. (B)</p> Signup and view all the answers

Which method is commonly used to treat oral thrush?

<p>Topical Nystatin. (D)</p> Signup and view all the answers

Identify the pH range that distinguishes Candida-related vaginal thrush from other forms of infectious vaginitis.

<p>4.0 - 4.5. (A)</p> Signup and view all the answers

What is the primary mechanism of how Candida cells establish cutaneous or mucosal candidiasis?

<p>Damaging skin or epithelial barriers. (C)</p> Signup and view all the answers

Which treatment requires escalation for cases of esophageal thrush?

<p>Topical treatments. (D)</p> Signup and view all the answers

Which of the following is NOT a risk factor specifically associated with genital thrush?

<p>Obesity. (A)</p> Signup and view all the answers

What is the primary risk factor for developing invasive Aspergillosis in immunocompromised patients?

<p>Long-term steroid use (D)</p> Signup and view all the answers

Which of the following describes a common clinical presentation of invasive Aspergillosis?

<p>Pleuritic chest pain and hemoptysis (C)</p> Signup and view all the answers

What is the reported mortality rate for patients with invasive Aspergillosis?

<p>22% (B)</p> Signup and view all the answers

Which diagnostic method has low sensitivity and specificity for identifying invasive Aspergillosis?

<p>Culture (D)</p> Signup and view all the answers

Which of the following is a risk factor for Pneumocystis jiroveci pneumonia in organ transplant recipients?

<p>Long-term corticosteroid use (C)</p> Signup and view all the answers

What distinct radiographic feature is associated with invasive Aspergillosis?

<p>Halo sign (A)</p> Signup and view all the answers

What major symptom is associated with Pneumocystis jiroveci pneumonia?

<p>Marked hypoxemia (C)</p> Signup and view all the answers

Which treatment approach is typically used for Pneumocystis pneumonia?

<p>Antibiotics specific for Pneumocystis (B)</p> Signup and view all the answers

What immune system condition increases the risk for Pneumocystis jiroveci pneumonia?

<p>Severe neutropenia (C)</p> Signup and view all the answers

Which organ transplant recipients have the highest incidence of Pneumocystis jiroveci pneumonia?

<p>Lung and heart-lung transplant recipients (A)</p> Signup and view all the answers

Which systemic fungal infection is a 60-year-old male in Tuscon, Arizona, at risk of contracting while on Humira?

<p>Coccioidomycosis (D)</p> Signup and view all the answers

Which of the following statements is NOT true regarding onychomycosis?

<p>Non-prescription OTC therapy is quite curative for this infection. (D)</p> Signup and view all the answers

Which characteristic is NOT associated with yeast?

<p>Prokaryotic (B)</p> Signup and view all the answers

Which type of mycosis affects the subcutaneous tissue?

<p>Subcutaneous Mycoses (D)</p> Signup and view all the answers

Which of the following conditions is most likely to involve a marked immunosuppression?

<p>Aspergillosis (B)</p> Signup and view all the answers

Which statement about Sporotrichosis is correct?

<p>Conidia can enter the skin through injuries from rose thorns. (D)</p> Signup and view all the answers

What is indiciative of infection by Candida species?

<p>Thickened, distorted, crumbly nails. (C)</p> Signup and view all the answers

What is a common feature of both cutaneous and subcutaneous mycoses?

<p>They both typically produce conidia. (D)</p> Signup and view all the answers

Flashcards

Cutaneous Mycoses

Fungal infections affecting the skin.

Subcutaneous Mycoses

Fungal infections beneath the skin.

Systemic Mycoses

Fungal infections that spread throughout the body.

Yeast

Unicellular fungi with a white or sometimes oval shape.

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Molds

Fungi with a filamentous structure (hyphae).

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Conidia

Asexual reproductive fungal spores.

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Pityriasis Versicolor

A superficial skin infection caused by the Malassezia genus.

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Fungal Cell Wall

A rigid structure that protects fungi and composed of carbohydrates, glycoproteins, and lipids.

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Malassezia furfur

A type of fungus that is a common cause of skin conditions like dandruff, often self-limiting and treatable with topical antifungals.

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Dermatophytosis

Fungal infection affecting the skin, hair, or nails, caused by dermatophytes (Trichophyton, Epidermophyton, Microsporum).

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Tinea corporis (ringworm)

A dermatophyte infection causing circular skin lesions with a red, scaling border, typically on smooth, non-hairy skin.

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Tinea pedis

A dermatophyte infection affecting the feet, often causing itchy red, vesicular or scaling lesions in between toes.

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Tinea cruris

A dermatophyte infection specific to the groin area, exhibiting red, scaling lesions that are itchy.

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Tinea capitis

A dermatophyte infection of the scalp, causing bald patches or hair breakage, can be inside or outside the hair shaft (endothrix or ectothrix).

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Tinea barbae

A dermatophyte infection of the beard area, presenting as red, edematous lesions.

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Tinea unguium

A dermatophyte infection of the nails, characterized by thickening, discoloration, and crumbling of the nail.

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Opportunistic fungal infections

Fungal infections that primarily affect individuals with weakened immune systems.

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CD4 count < 200 cells/µl

A critical level of immune cells (CD4) associated with increased susceptibility to opportunistic infections, including fungal infections.

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Candidiasis

Fungal infection caused by Candida species, yeasts that are commonly found in the body.

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Mucormycosis

Fungal infection from Mucorales molds, often affecting the sinuses, brain, or eyes.

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Rhinocerebral mucormycosis

A severe form of mucormycosis starting in the nasal passages and spreading to brain or surrounding areas.

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Risk factors for mucormycosis

Conditions like diabetes, leukemia, chronic steroid use, severe burns, and immunodeficiencies increase risk.

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Candida species

Various types of Candida yeast which can cause the infection candidiasis.

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Opportunistic Pathogens

Microbes that do not usually harm healthy hosts but can cause disease when immunity is suppressed.

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Candida species colonies

Soft, cream-colored colonies with a yeasty odor on agar media within 24 hours at 37°C or room temperature.

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Germ tube production

Only Candida albicans species produces a germ tube.

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Candidiasis pathogenesis (cutaneous/mucosal)

Increased local Candida population and damaged skin/epithelium allow local invasion.

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Systemic candidiasis

Bloodstream entry of yeast with inadequate host defenses against yeast growth.

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Thrush risk factors

HIV/AIDS, other immunodeficiencies, pregnancy, diabetes, age (young/old), oral contraceptives, antibiotics, and steroids are associated with thrush.

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Vaginal thrush

Second most common cause of vaginal infections among women of reproductive age.

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Vaginal thrush clinical presentation

Vulvar pruritus, burning, soreness, and dysuria are common; symptoms are worse before menstruation. Discharge is typically white, thick, clumpy, and with minimal odor. Vaginal pH is normal (4-4.5), visible budding yeast in wet mount.

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Candida cell components

Candida cells release polysaccharides, proteins, and glycoproteins to stimulate host defenses and aid host cell invasion.

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What is the role of corticosteroids in treating pneumonia?

Corticosteroids, like methylprednisolone or prednisone, are indicated for pneumonia when a patient's PaO2 (partial pressure of oxygen) is less than 70 mmHg. They are used to reduce inflammation and improve lung function, ultimately leading to shorter hospital stays, reduced fever duration, and lower chances of needing ventilation or ICU admission.

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What is the difference between superficial mycoses and systemic mycoses?

Superficial mycoses are fungal infections that affect the outermost layers of the skin, hair, and nails. Systemic mycoses, on the other hand, involve deeper tissues and organs throughout the body, often requiring systemic antifungal treatment.

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What is a common risk factor for systemic mycoses?

Immunosuppression, either due to medications or underlying conditions, can increase the risk of contracting systemic mycoses. This is because a weakened immune system is less able to fight off fungal infections that may be normally controlled.

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In a patient with rheumatoid arthritis on Humira, what fungal infection might be of concern?

Coccidioidomycosis, a systemic fungal infection commonly found in the Southwestern US, particularly Arizona. Immunosuppressants like Humira (adalimumab) can weaken the immune system, making individuals more susceptible to this infection.

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What is budding in yeast?

Budding is the primary method of reproduction for yeast. In this process, a small outgrowth or bud forms on the parent cell and eventually separates to become a new, independent yeast cell.

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What is a key characteristic that distinguishes yeast from molds?

Yeast are unicellular organisms, meaning they consist of only one cell. In contrast, molds are multicellular and composed of long, filamentous structures called hyphae.

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What is the most common type of fungus causing onychomycosis?

Molds are more commonly associated with onychomycosis compared to yeast. While both can cause the infection, molds play a larger role in this nail fungal infection.

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How can Sporotrichosis be contracted?

Sporotrichosis is often contracted through skin punctures from contaminated objects such as rose thorns. The fungal conidia, which are infectious spores, can enter the body through these injuries.

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Aspergillus flavus

A type of mold that produces small airborne spores (conidia) which can cause allergic and respiratory problems in susceptible individuals.

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Bronchopulmonary Aspergillosis

A lung disease caused by Aspergillus flavus, which occurs in people with weakened immune systems and can lead to lung inflammation and infection.

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Invasive Aspergillosis

A serious fungal infection that spreads to the blood and other organs, mainly affecting people with compromised immune systems.

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How does Aspergillus affect immunocompromised patients?

In immunocompromised patients, Aspergillus conidia can germinate into hyphae, which can invade the lungs and other organs. These patients often lack the immune cells needed to fight off the infection.

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What is the mortality rate of Invasive Aspergillosis?

The mortality rate of Invasive Aspergillosis is around 22%, highlighting its severity.

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Pneumocystis jiroveci Pneumonia

A serious lung infection caused by a fungus called Pneumocystis jiroveci. It commonly affects people with weakened immune systems, particularly those with HIV.

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What is the risk of Pneumocystis jiroveci Pneumonia in solid organ transplant recipients?

The incidence of Pneumocystis jiroveci pneumonia is highest in lung and heart-lung transplant recipients, particularly those not receiving adequate prophylaxis.

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What are some risk factors for Pneumocystis jiroveci Pneumonia?

Risk factors include high-dose or long-term corticosteroid use, antilymphocyte therapy, calcineurin inhibitor use (tacrolimus, cyclosporine), frequent organ rejection, exposure to an infected patient, low CD4 counts (HIV), infection with CMV, prolonged neutropenia.

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Clinical presentation of Pneumocystis jiroveci Pneumonia

Patients may present with fever, abnormal radiographs, cough, hypoxemia, dyspnea, or chest pain. A marked drop in oxygen levels (hypoxemia) is often seen, even despite seemingly mild symptoms.

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Treatment of Pneumocystis Pneumonia

Pneumocystis jiroveci pneumonia is treated with specific antibiotics, not standard antifungals.

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Study Notes

Medical Mycology

  • This is the study of fungi
  • 80,000 species of fungi have been described
  • Less than 50 cause more than 90% of fungal infections in humans and other animals
  • Fungal infections are called mycoses
  • Most pathogenic fungal infections come from exogenous sources like water, soil, and organic debris
  • Other infections are caused by fungi part of the normal human flora.
  • Different fungi can cause superficial, cutaneous, subcutaneous, or systemic infections. Opportunistic infections occur in immunocompromised patients.

Fungal Infections: Types

  • Superficial: Affect the epidermis (e.g., tinea versicolor, ringworm)
  • Cutaneous: Affect keratinized tissue (e.g., skin, hair, and nails. Athlete's foot, jock itch, onychomycosis are part of this group).
  • Subcutaneous: Affect subcutaneous tissues (e.g., sporotrichosis)
  • Systemic: Invade internal organs (e.g., histoplasmosis, cryptococcosis, aspergillosis, and various forms of candidiasis)
  • Opportunistic: Occur when the immune system is weakened (e.g., candidiasis in patients with HIV/AIDS)

Fungal Classification

  • Yeast: Unicellular, oval shaped
  • Molds: Multiple identical nuclei/consisting of branching tubular hyphae
  • Reproduction types: mitosis and budding in yeast, spores for molds

Mycological Infections: Specific Examples

  • Histoplasmosis: Caused by Histoplasma capsulatum
  • Coccidioidomycosis: Caused by Coccidioides immitis
  • Blastomycosis: Caused by Blastomyces dermatitidis
  • Paracoccidioidomycosis: Caused by Paracoccidioides brasiliensis
  • Sporotrichosis: Caused by Sporothrix schenckii
  • Mycetoma (Madura Foot): Caused by soil dwelling fungi
  • Candidiasis: Caused by Candida species (a common yeast normally found on skin and mucus membranes), a common systemic mycosis

Fungal Infections: Onychomycosis

  • Fungal infection of the nails
  • Infection starts under the nail plate (hyponychium)
  • Nails appear thickened, distorted, crumbly, and yellowed
  • Mold, rather than yeast, is the more common cause
  • OTC therapy not very effective

Fungal Infections: Cryptococcosis

  • Caused by Cryptococcus neoformans
  • Occurs in 6-10% of AIDS patients
  • Usually found in the environment
  • Presents commonly as meningitis in immunocompromised individuals

Fungal Infections: Aspergillosis

  • Caused by Aspergillus species
  • Often causes pneumonia in immunocompromised patients
  • Can lead to vascular invasion, tissue necrosis, thrombosis, and dissemination to other organs
  • Can be influenced by medications that cause false positive assays or test results

Fungal Infections: Pneumocystis Pneumonia

  • Caused by Pneumocystis jiroveci
  • Primarily affects immunocompromised patients (e.g., HIV/AIDS)
  • Characterized by marked hypoxemia (low oxygen levels)

Fungal Infections: Candidiasis

  • Caused by Candida species
  • Common in immunocompromised individuals
  • Can cause oral thrush or vaginal thrush

Treatments (general)

  • Treatment depends on the specific type of mycosis and patient factors
  • Often include: surgical/mechanical removal, topical/oral antifungals, and/or systemic antifungal medications.
  • In some cases, a combination of therapies may be required.

Risk factors for medical mycoses

  • Immunocompromised individuals (HIV/AIDS, transplant patients)
  • Use of corticosteroids or other immunosuppressant medications
  • Diabetes
  • Certain procedures (e.g., surgical procedures, catheters)
  • Medications like SGLT-2 inhibitors

Important Considerations/Additional Notes

  • Geographic areas and environments can predispose to certain infections
  • Some fungi are dimorphic (exist in both mold and yeast forms depending on environmental conditions)
  • Fungi infections are often associated with other medical issues.
  • Proper diagnosis is essential to provide appropriate treatment for each type of infection

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Description

Explore the fascinating world of fungi with this quiz on Medical Mycology. Learn about the different types of fungal infections, their causes, and how they impact human health. From superficial to systemic infections, test your knowledge and understanding of mycoses.

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