Fungi

Blastomyces dermatitidis

- causes clastomycosis - dimorphic fungus - present in decaying organic matter such as wood or leaves - acquired via inhalation of airbone conidia manifestations - asymptomatic in 50% of cases - 3weeks- 3 months after exposure: cough, night sweats, joint pain, chest pain, fatigue, body aches - in severe cases, the fungi can disseminate to the skin, bones, CNS treated with amphotericin B or itraconazole

Which Candida species occur most commonly as a culprit of fungal infection? A. C. auris B. C. humilis C. C. glabrata D. C. rugosa

C. C. glabrata C. glabrata is known to be an invasive pathogenic Candida species. C. auris is pathogenic to humans, but it was first described in 2009 and has only been recently identified (2016) as the causative agents for some small hospital outbreaks worldwide; despite this, it is not nearly as widespread as C. glabrata infection at this time. C. humilis is not typically pathogenic and occurs within sourdough. C. rugosa is pathogenic but not widespread.

Bread mold (Rhizopus stolonifer) are saprobes that rapidly propagate on the surface of bread, fruits, and vegetables, living off of decaying organic material. What is the classification of this fungus? A. Ascomycota B. Basidiomycota C. Chytridiomycota D. Zygomycota

D. Zygomycota Rhizopus stolonifer is an example of Zygomycota, a type of rapidly growing saprobe fungi that lives off of decaying organic material, such as breads, fruits, and vegetables. Ascomycota, the sac fungi, form a sac-like structure containing haploid spores. Basidiomycota are known as the club fungi, characterized by club-shaped fruiting bodies called basidia. Chytridiomycota are the simplest and most primitive type of fungi, typically found in freshwater environments.

Crytococcus neoformans

- causes crytococcosis - present in decaying wood, soil, bird droppings - acquired through inhalation of spores from the environment - the infection may be cleared, become latent, cause pulomary infection, or disseminate to other body parts, typically the CNS manifestations - most are asymptomatic - usually infects the lungs first- cough, shortness of breath, chest pain, fever - can spread to brain (crytococcal meningitis)- headache, fever, neck pain/stiffness, nausea/vomiting, light sens., confusion - most dangerous for immunocompromised patients treatment: - fluconazole - severe infections: fluconazole + amphotericin B

Histoplasma capsulatum

- dimorphic fungus (yeast/fungus depending on env) - causes histoplasmosis - acquired from airbone conidia in areas with bird or bat droppings manifestations - fever, cough, fatigue, chills, headache, chest pain, body aches - forms lung lesions - most are asymtomatic - usually self limiting - can become disseminated in immunocompromised patients (moving to other parts of body) treated with amphotericin B or itraconazole

Dermatophytosis

- fungal infection of the skin - known as tinea or ringworm - caused by fungi in the genera Trichophyton, Microsporum, Epidermophyton - fungi metabolize keratin -tinea capitis- scalp ringworm - tinea cruris- jock itch - tinea pedis- athlete's foots - tinea unguium- ringworm of nails -treated with topical drugs: miconazole and clotrimazole

Fungal Keratitis

- fungual infection of the cornea - caused by fungi from the genera Fusarium, Aspergillus, Candida - very rare, could lead to blindness - often associated with contaminated cls manifestations - eye pain, redness, blurry va, light sens., tearing, discharge - if left untreated, va loss diagnosed by clinical picture and culture treated with topical antifungal for several weeks to months: natamycin, voriconazole, amphotericin

Candida albicans

- yeast - normal flora of the skin and some mucous membranes (mouth, genitourinary tract) - cadidiasis is an abnormal overgrowth- results when antibiotics supress competing bacteria, or a change occurs in thw mucosal pH. thrush- overgrowth in the oral cavity - can cause fulminating disease in the immunosupressed (meningitis, pneumonia) manifestations - candidiasis of the mouth and throat- white patches on the inner cheeks, younge, roof of the mouth, and throat; redness or soreness; cottonmouth; loss of taste; pain while eating or swallowing - vaginal candidiasis- vaginal itching or soreness; pain during sex; pain or discomfort when urinating; vaginalo discharge treatment - topical clotrimazole, miconazole, nystatin - severe infections: oral flucoazole

A 26-year-old man presents with fever of 101°F, dry cough, night sweats, fatigue, muscles aches, and decreased appetite for the past 4 days. He has a history of chronic hepatitis B. He does not take any medications, does not recall any sick contacts, and has not been to the hospital for 3 years. He traveled to the Great Lakes last month and participated in various outdoor activities. Potassium hydroxide preparation of sputum showed a round organism with a doubly refractile wall and a single broad-based bud. What organism is the most likely cause of infection? A. Blastomyces dermatitidis B. Cryptococcus neoformans C. Francisella tularensis D. Mycobacterium tuberculosis

A. Blastomyces dermatitidis Acute pulmonary blastomycosis usually presents with non-specific symptoms of fever, cough, night sweats, loss of appetite, fatigue, chest pain, myalgias, and arthralgias, leading to potential confusion with many other pathogens. Infection risk factors include travel to endemic areas in the US, such as midwestern, south-central, and southeastern states, particularly the Ohio and Mississippi River valleys and the Great Lakes. Transmission of blastomycosis is usually via inhalation. Cryptococcus neoformans is a round organism on microscopy, typically seen as an encapsulated yeast by India ink preparation. Infection with Cryptococcus neoformans is rare without immunodeficient risk factors such as HIV or immunosuppressive therapies. F. tularensis, the causative organism of tularemia, is a zoonotic disease that can infect people through contact with ticks or deer flies commonly on rabbits and other animals. People can also be exposed to tularemia from contaminated water, aerosols, and bioterrorism. This patient is exposed to the outdoors, but the microscopic examination is not typical for F. tularensis. Tuberculosis presents with similar signs and symptoms, but this patient's exposure to tuberculosis is unlikely, as he does not have healthcare contacts. Also, his recent travel to a blastomycosis-endemic area increases suspicion for blastomycosis.

Club fungi, such as mushrooms and shelf fungi on tree trunks, are characterized by their club-shaped fruiting bodies. What is their classification? A. Ascomycota B. Basidiomycota C. Deuteromycota D. Zygomycota

B. Basidiomycota Basidiomycota, such as mushrooms, shelf fungi, and toadstools, are characterized by the presence of club-shaped fruiting bodies called basidia, which are the reproductive organs of these fungi. Other types of fungus do not contain basidia as a part of their sexual reproductive cycles. Ascomycete reproduction is characterized by the formation of a sac-like structure containing haploid ascospores. Deuteromycete reproduction is strictly asexual, occurring primarily through production of asexual conidiospores. Zygomycetes usually reproduce asexually by producing sporangiospores, growing at the end of stalks.

What is the primary portal of entry for Blastomyces dermatitidis? A. Eyes B. Lungs C. Mucous membranes D. Wounds

B. Lungs The lungs are the primary portal of entry for Blastomyces dermatitidis—acquired through inhalation of airborne conidia. Eyes, mucous membranes, and wounds are not the primary portal of entry for this infection.

What population is most susceptible to fungal infections? A. Ashkenazi Jewish patients B. Organ transplant recipients C. Patients with cystic fibrosis D. Patients who work with wild animals

B. Organ transplant recipients Those undergoing an organ transplant are most susceptible to fungal infections secondary to taking immunosuppressant medications. Ashkenazi Jewish patients are associated with neurological malformations. Patients with cystic fibrosis are at higher risk for deep lung bacterial infections. Patients who work with wild animals may be susceptible to parasitic infections from a vector.

Aspergillus niger is a common food contaminant and is considered an imperfect fungus that does not have a sexual phase of reproduction. What type of fungus is it? A. Ascomycota B. Basidiomycota C. Deuteromycota D. Zygomycota

C. Deuteromycota Deuteromycota are fungi that do not undergo a sexual phase of reproduction—only asexual reproduction. Examples of this form of fungi include Aspergillus niger and Penicillium. Other types of fungus undergo both asexual and sexual phases of reproduction.

Arbuscular mycorrhizas help plants capture nutrients (phosphorus, sulfur, nitrogen) and micronutrients from the soil. These fungi do not reproduce sexually and cannot survive without a symbiotic association with plant roots. What type of fungus are these? A. Ascomycota B. Chytridiomycota C. Glomeromycota D. Zygomycota

C. Glomeromycota Glomeromycota, a newly established phylum of fungus, consists of species of fungus that live in a close highly evolved symbiotic association with the roots of plants. Glomeromycetes form a mutually beneficial association with plants; plants supply a source of carbon and carbohydrates to the fungus, and the fungus supplies essential nutrients from the soil to the plant. The other types of fungus do not form this type of symbiotic association; they may survive as parasites or live off of decaying organic matter.

What fungus can cause respiratory disease and is associated with birds and bats in the Mississippi and Ohio River Valleys? A. Blastomyces dermatitidis B. Epidermophyton C. Histoplasma capsulatum D. Microsporum

C. Histoplasma capsulatum Histoplasma capsulatum, associated with bats and birds of the Ohio and Mississippi River Valleys, is a fungal species that can cause serious lung disease. Many fungal species of ascomycetes are medically important. Many can lead to skin and nail infections, such as Microsporum, Trichophyton, and Epidermophyton. Blastomyces dermatitidis is a dimorphic fungus that causes blastomycosis, a type of respiratory infection.

What characteristic explains how Blastomyces dermatitidis can exist as a yeast in human tissue and a mold in the environment? A. Ectothermic B. Stenothermal C. Thermally dimorphic D. Thermophilic

C. Thermally dimorphic Thermally dimorphic refers to how Blastomyces dermatitidis can grow as a mold in the environment and as yeast in humans. Ectothermic refers to cold-blooded animals. Stenothermal relates to the ability of an animal to tolerate a narrow range of temperatures. Thermophilic organisms survive in high temperatures