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74 Cards in this Set
- Front
- Back
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Where is Sporothrix schenckii found? |
In soil and on plants (rose thorns and splinters).
Gardeners |
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What is the feature of of tinea nigra and what is it caused by?
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Causes dark brown to black painless patches on the soles of the hands and feet.
Caused by Exophiala werneckii. |
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How can you treat pityriasis versicolor and tinea nigra?
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Spreading dandruff shampoo containing selenium sulfide over the skin.
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Where do dermatophytic fungi live? What do they secrete and what is the result of this?
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Dead, horny layer of the skin, hair, and nails.
They secrete keratinase, which digest keratin. This causes scaling of the skin, loss of hair, and crumbling of nails since they are all related to keratin. |
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What causes dermatophytoses? Their diagnostic form?
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Microsporum: spindle-shaped macroconidia
Trichophyton: microconidia Epidermophyton: dumbbell-shaped macroconidia |
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What are the features of dermatophytoses?
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Tinea corporis: fungi spread in the skin, resulting in a ring shape lesion with a red, raised border. This is called a ring-worm, since it looks like a ring-shaped worm under the skin.
Tinea cruris: Jock itch Tinea pedis: athlete's foot. Causes cracking and peeling of skin. Requires warmth and moisture, therefore, only occurs in those who wear shoes. Tinea capitis: loss of hair Tinea unguium (onychomycosis): nails are thickened, discolored, and brittle. |
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How do you diagnosis dermatophyte infection?
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Skin scrapings in KOH. Also, Wood's light.
Wood's light detects some species of Microsporum, which causes hairs to fluoresence. They grow on Sabouraud dextrose agar |
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DOC for dermatophytoses?
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DOC: imidazoles or griseofulvin (Nath). Griseofulvin concentrates in keratinized areas of the body.
Hair follicles and nails: oral agents such as terbinafine and azoles (fluconazole and itraconazole). |
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Conidia of dermatophyte molds are found as?
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Arthroconidia: infective form
Macroconidia and microconidia: diagnostic form. |
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Tinea is used to describe?
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A common presence of serpentine (snake like) and annular lesions that occur on skin, making it appear that a worm is burrowing at the margin.
Note: nodular and vesicular lesions are also noted. |
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Dermatophytes are restricted to?
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Dead cornified layer of the epidermis.
Humid or moist skin provides for a favorable environment. They do not disseminate. |
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What is sporotrichosis?
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Following a prick by a thorn (e.g., rose thorn), a subcutaneous nodule gradually appears. The nodule becomes necrotic and ulcerates. The ulcer heals, but new nodules pop up nearby and along the lymphatic tracts or streaks up the arm.
Note: Sporothrix schenckii is a subcutaneous fungal infection. |
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What is the DOC for sporotrichosis?
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Potassium iodide for mild subcutaneous disease.
Itraconazole is highly effective and better tolerated in lymphocutaneous and osteoarticular disease. |
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Direct tissue stain of Sporotrix schenckii at 37d reveals?
When cultured on SDA at 22d C |
Subglobose-to-ovoid (cigar-shaped) yeast.
Reveals darkly pigmented mold. Branched hyphae and microconidia appear as floral (daisy) arrangements. |
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Describe the appearance of Sporothrix schenckii?
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Initial erythematous papulonodular lesion evolve into a smooth painless nodules that may ulcerate and drain.
Lymphatic spread results in chain of nodular lesions that typifies lymphocutaneous form of the disease (lymph nodes are not involved). Lesions are suppurating granulomas with histiocytes and giant cells. Subcutaneous lesions are hard, lumpy, and crusted. Lesions periodically exude fluid and do not heal. |
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Pneumocystis jiroveci includes what two forms and what stains can be used?
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Trophozoites (Giemsa) and cysts (silver)
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How common is Pneumocystis jiroveci? And when does this fungus become problematic and what happens?
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It is ubiquitous. Most children have ABs to it by their 5th year.
When one's CD4+ count reaches below 200. |
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How do you treat candidiasis?
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Cutaneous, such as vaginal: topical antifungal agents (e.g., clortimazole)
Thrush/esophagitis/deep tissue: fluconazole Systemic and for severely ill: amphotericin B |
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Pneumocystis jiroveci binds with fibronectin and glycoproteins to?
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Type I pneumocytes.
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How do you test for Candida albicans
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KOH smear
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Since Pneumocystis jiroveci remain extracellular, what damage occurs with them?
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They damage the basement mm, leading to alveolar capillary permeability. This leads to increase in phospholipase activity and deficiency of surfactant secretion by type II cells.
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With is the most common esophageal disease with PTs having AIDS? How does it present?
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Candidias. It presents as dysphagia and chest pain.
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Once type II cells stop secreting surfactant, what happens?
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There is a ventilation/perfusion mismatch.
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How does oral thrush present with Candida infection?
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White plaques that adhere to the tongue and buccal mucosa.
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What develops in the alveoli from Pneumocystis jiroveci?
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A foamy exudate and interstitial pathology (radiology reveals bilateral ground glass appearance).
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Aspergillus fumigatus can cause what 3 diseases?
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Allergic Broncho-Pulmonary Aspergillosis (ABPA); Aspergilloma; invasive aspergillosis.
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What is the DOC for Pneumocystis jiroveci?
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TMP-SMX. Alternative is pentamidine or atovaquone.
Once PO2 decreases below 70, steroids can improve mortality. |
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What is Allergic Broncho-Pulmonary Aspergillosis (ABPA)?
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Type I hypersensitivity with IgE response resulting in bronchospasm--asthma. Type IV can occur with cell-mediated inflammation and lung infiltrates.
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Describe the vaginal discharge from Candida, Trichomonas, andbacterial vaginosis?
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Candida is whitish discharge that can be thick or curdy.
Trichomonas is yellow and frothy Bacterial vaginosis is foul smelling |
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What is Aspergilloma?
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From previous lung cavitations from tuberculosis or tumor, aspergillus can grow as a fungal ball in the cavity. This can result in life-threatening hemoptysis.
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What is the most common opportunistic infection of AIDS?
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Pneumocystis jiroveci
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What occurs with invasive aspergillosis?
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Occurs in immunocompromised hosts. It invades lung tissue and bloodstream, resulting in pulmonary infarction.
It can present as asymptomatic pneumonia characterized by multiple nodular infiltrates. |
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Candida species are yeast. In secretions (wet preparations) and tissue secretions, they can be?
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Pseudohyphae or true hyphae.
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What toxins does Aspergillus fumigatus secrete?
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Aflatoxin, which contaminates decaying vegetation: peanuts, grains, and rice and can result in liver carcinoma.
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Candida infections are acquired by? What are the predisposing factors?
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Endogenously, not environmental.
Predisposing factors for vaginal candidiasis are: feminine hygiene products, contraceptives, vaginal medications, broad spectrum antibiotics, sexual intercourse, pregnancy, stress, and diabetes mellitus. |
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What are mycotoxins?
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Toxins secreted by fungi that can cause liver damage and liver cancer.
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Yeast reproduce by?
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Budding
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What is the most common mold that cause human disease?
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Aspergillus fumigatus
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How can C. albicans be differentiated from other speices?
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By its production of germ tubes (short hyphal filaments).
It also has chlamydospores, the reproductive, thick-walled structures of the fungus, larger than the standard spores produced by the molds. |
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What is the morphology of Aspergillus?
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Thin hyphae that branch at V-shaped (45d angle)
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What is the most common fungus causing human disease?
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Candida species, and they are part of the normal flora of the GI, mouth, and female genital tract.
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How do you become contaminated by Aspergillus?
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Inhalation from condidia (spores).
Cytotoxic drugs that lead to neutropenia greatly increases susceptibility. |
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What are the clinical presentation of Candida albicans?
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Normal host: thrush, vaginitis (yeast infection after broad-spectrum antibiotic), and diaper rash (under large breast), and into the urinary tract via an indwelling bladder catheter.
Immunocompromised host:esophagitis and systemic infection |
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How does Aspergillus cause hemoptysis?
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Hydrolases (serine protease or phospholipase) and hemolysin are angioinvasive pathogen involved in endothelial damage.
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How does Candida albicans occur with someone who is immunocompromised?
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Infections spread from normal flora: from mouth to esophagus (esophagitis); local to systemic sites (disseminated candidiasis)
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Is Aspergillus invasive? How does it colonize?
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Yes. It has adhesins that are involved in the colonization of lower respiratory airways.
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What is involved in elimination of Aspergillus?
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Neutrophils and dust cells.
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How do you treat Aspergillus?
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Voriconazole is the DOC. Amphotericin B was the the standard in years past.
Granulocyte-colony stimulating factor can be given to improve neutrophil count. |
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What three fungi cause systemic disease in humans? How are they cultured?
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Histoplasma capsulatum, Blastomyces dermatitidis, and Coccidioides immitis.
All three are dimorphic fungi: At 25d, they are branched hyphae. At 37d, they are yeast; therefore, they are yeast in humans. Histoplasma: yeast are thin-walled, oval structures. Blastomyces: on Sabouraud agar at 25d, is a white fluffy mold. At 37d, brown, wrinkled colonies as large yeast with broad-based budding. Coccidioides: white fluffy mold but rarely done due to biohazard. |
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What are the geographic regions of Coccidioiomycosis, Histoplasmosis, and Blastomycosis?
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Coccidioiomycosis: endemic to the southwestern US.
Histoplasmosis and Blastomycosis: Mississippi river region. Histoplasmosis in parts of central and eastern US along Ohio. Blastomycosis east of Mississippi, southeastern region of US. |
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How are Coccidioiomycosis, Histoplasmosis, and Blastomycosis spread?
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As inhaled spores from soil, bird or bat droppings, or vegetation.
Conidia become airborne when contaminated soil is disturbed. |
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What are the clinical presentation of Coccidioiomycosis, Histoplasmosis, and Blastomycosis?
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Asymptomatic: majority of cases
Pneumonia: like TB, granulomas with calcifications can follow resolution of pneumonia. Smaller group progresses to chronic cavitary pneumonia with weight loss, night sweats, and low-grade fevers. Dissemination: Histoplasma (reticuloendothelial system: liver, spleen, and bone marrow); Blastomyces (lymphohematogenous spread to other organs; verrucous skin lesions with pustular features); coccidioides (granulomas throughout the body and erythema nodosum lesions). meningitis, bone lytic granulomas, skin granulomas that break down into ulcers and other organ lesions. |
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The growth of the mold Histoplasma capsulatum results in?
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Aerial mycelial growth that produces characteristic macroconidia (thickwall; finger-like projections) and microconidia.
It produces glycoproteins H and M. |
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The growth of the mold Histoplasma capsulatum results in?
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Aerial mycelial growth that produces characteristic macroconidia (thickwall; finger-like projections) and microconidia.
It produces glycoproteins H and M. |
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How did Histoplasma obtain its name?
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They are found in histiocytes (macrophages, such as dust cells) as yeast.
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What is the DOC for Histoplasma capsulatum, Blastomyces dermatitidis, and Coccidioides immitis?
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Itraconazole. With severe symptoms, amphotericin B.
For meningitis, fluconazole is preferred for excellent CSF penetration. |
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What forms arthroconidia and what is it? What does it transform into in the pulmonary alveoli?
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Coccidioides immitis. When the soil is disturbed, the hyphae fragment and form extremely hardy structures called arthroconidia, which becomes airborne.
It can transform into a thick-walled, nonbudding spherules that can form septa and produce endospores. Each endospore is capable of forming new spherules or mycelia. |
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What is rarely done with Coccidioides immitis?
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Culture since it is a biohazard.
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What is the test of choice for Coccidioimycosis.
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Serology (agar immunodiffusion).
Same with Histoplasmosis, or blastomycosis? |
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Coccidioides immitis is endemic where?
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Southwestern US
In San Joaquin Valley, is known as "valley fever" |
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How does infection of C. immitis occur?
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They are in arid soil and around rodent burrows. Infection occurs from inhalation of arthroconidia that are deposited in the terminal bronchiole. There is a chronic granulomatous inflammation. Caseation without calcification may occur.
Dissemination to skin produces erythema nodosum. Can also disseminate to bones, joints, and meninges. |
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How do you classify Actinomyces and Nocardia?
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They are gram + bacteria with beaded filaments that act like fungi.
Actinomyces: not acid fast, obligate anaerobe. Nocardiosis: weakly acid fast obligate aerobe. |
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What does Actinomyces Israelii cause?
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It is part of the normal flora.
After trauma, Actinomyces Israelii causes eroding abscesses: mouth, lungs, GI tract, and GU tract. The suppurative abscess spreads mainly by direct extension to other tissue planes. Infection is named according to area of the body: cervicofacial actinomycosis, abdominal actinomycosis, etc. Note: the organisms is unable to cause infection alone and requires synergistic presence of other commensals. |
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When examining Actinomyces Israelii under the microscope, what does the pus look like?
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Sulfur granules--although not composed of sulfur.
Note: Israel has yellow sand. |
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How do you treat Actinomyces Israelii?
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Penicillin G and surgical drainage.
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Why are Nocardia asteroides frequently misdiagnosed?
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They are frequently misdiagnosed as TB because it is acid-fast and causes the same disease process.
They can produce lung abscesses and cavitation. Note: They are facultative intracellular bacteria within phagocytic cells that results in granulomatous inflammation. Lung pathology is inflammatory endobronchial masses or diffuse pneumonitis and abscess. |
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What is the pathology behind Nocardia asteroides?
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Pneumonia and abscesses in kidney and brain.
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What group is most susceptible to Nocardia asteroides?
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Immunocompromised PTs, such as those taking steroids or AIDS PTs
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Where are Nocardia asteroides found and how do they proliferate during an infection?
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They are found in the soil and are inhaled.
Mycolic acid cell wall allows intracellular survival and proliferation. |
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How do you treat Nocardia asteroides?
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Trimethoprim and sulfamethoxazole.
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What causes Madura foot?
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Nocardia asteroides. It is a skin inoculation in agricultural workers presenting as a chronic subcutaneous infection, characterized by either slow extension along lymphatics or by destruction of deeper tissues.
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What is diagnostic of Actinomyces israelii?
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Molar tooth colonies form sulfur granules from a draining sinus.
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What are two superficial fungal infections associated with pigment change on the skin?
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Pityriasis versicolor and tinea nigra
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What is the feature of pityriasis and what is it caused by?
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Leads to hypopigmentation or hyperpigmentation.
With sunlight exposure the skin around the patches will tan, but the patches will remain white. Caused by Malassezia On KOH skin scraping, demonstrates a characteristic "spaghetti and meatball" appearance. |
