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WVSOM - Candida

Candida

QuestionAnswer
Opportunistic pathogens can cause diseases in ... Diabetics, newborn, old aged, immunocompromised, person on corticosteroids, person on broad-spectrum antibiotics, neutropenic
Candida spp. cause what type of diseases Opportunistic, superficial, cutaneous, subcutaneous, systemic
What adaptive immune cell controls Candida in the healthy host? T cells
What T cell subset and cytokine is critical in host defense against Candida? Th1 and IFN-gamma
What locations can Candida colonize? Oral, GI, vaginal, cutaneous epithelium
Which is the most prevalent opportunistic fungal pathogen in humans? Candida
How do fungi grow at body temperature? Yeast - single cells
How do yeast reproduce? Budding (can also produce pseudohyphae)
How do fungi grow at room temperature? Mold - multicellular filaments called hyphae
A dense mat of hyphae (mold) is called? Mycelium
How do hyphae reproduce? By asexual reproduction, producing conidia
What class does Candida belong to? Fungi imperfecta
How will Candida present in tissues? As yeast and as yeast with pseudohyphae
Candida are part of the normal flora of which system? GI
What other areas does Candida colonize? Oral cavity and skin
Which Candida species causes 50% of fungal infections? Candida albicans
What Candida species is resistant to anti-fungals? Candida krusei
What Candida species is prominent in Europe and Africa? Candida dubliniensis
List the most common species of Candida Candida albicans, Candida tropicalis, Candida parapsilosis, Candida glabrata, Candida guilliermondii, Candida krusei, Candida dubliniensis, Candida inconspicua
The cell wall of yeast contain ... B-glucan
What do dendritic cells and macrophages recognize on yeast? They have receptors that recognize B-glucan
What do DCs and macrophages release in response to B-glucan? IL-12
IL-12 produces which T cell subset? Th1
Th1 releases what? IFN-gamma
What does IFN-gamma do? It increases the ability of macrophages to phagocytose pathogens
What does antibody do with regard to Candida immunity? Neutralizes yeast; provides humoral immunity
What are some diseases caused by Candida? Most benign, more extensive and persistent, invasive focal infections, widespread visceral dissemination
Benign disease caused by Candida Local overgrowth on mucous membranes often due to changes in bacterial normal flora
Example of benign disease caused by Candida Thrush
More extensive and persistent diseases caused by Candida Overgrowth on mucous membranes in patients with deficiencies in cell-mediated immunity (ex: AIDS)
Invasive focal infections caused by Candida Occur following hematogenous spread and affect multiple organs (pyelonephritis, endocarditis, meningitis); in-dwelling devices (prosthetic heart valves, catheters)
Widespread visceral dissemination caused by Candida In neutropenic or severely ill patient in ICU; occurs when Candida gains access to bloodstream
Who is most at risk for Candida infections? Immunocompromised host and patients in ICU
Clinical manifestations of Candidemia and invasive Candida Range from minimal fever to full-blown sepsis syndrome indistinguishable from bacterial sepsis; may observe multiple organ failure
Location of widespread visceral abscesses associated with Candidemia and invasive Candida Liver, kidney, heart, spleen, lungs, eyes, brain
How do you acquire Candida? From people, animals, water, soil, food
What are some risk factors or predisposing factors for Candida infections? Immunodeficiency, diabetes, cancer, neutropenia, long-term corticosteroids, broad-spectrum & long-term antibiotics, prolonged hospital stay (especially with catheterization), alterations in skin / GI integrity (surgery, burn patients), in-dwelling devices
How does Candida adhere to epithelial or mucosal surfaces? Via fungal adhesins
What are the three steps required for Candida pathogenesis? Adherence, invasion, host cell damage
What allows for a more virulent Candida infection (with regard to adherence)? Stronger cellular adherence (also species and strain differences)
What is necessary for C. ablicans hyphal growth? Physical contact
What (of the fungi) contacts the surface of host cells? Cell wall proteins
Invasions requires ... Hyphal growth
What process occurs for yeast to invade host cells? Morphogenesis into hyphal forms
What do invasins degrade? Extracellular matrix proteins
How do hyphae enter host cells? Active penetration or induced endocytosis (hyphae can also grow btw cells)
What two hydrolytic enzymes cause tissue damage? Proteases and phospholipases
Morphogenesis Yeast form can differentiate into pseudophyphae and true hyphae and cause tissue damage via tissue invasion (yeast-to-hyphal transition)
What is phenotypic switching (with regard to Candida pathogenesis)? Allows Candida to adapt to changes in host environment produced by antibiotics, immune response, or altered host physiology; metabolic & catabolic genes can be turned on / off depending on tissue environment
How does Candida evade the immune system? Suppresses production of ROS via NADPH oxidase complex & nitric oxide production; proteases degrade LFA-1; produces catalases that neutralize H2O2; produces adenosine which blocks neutrophil oxygen radical production & degranulation
Why do we need a Candida vaccine? Prevent life-threatening systemic infections
What kind of vaccine would be a logical choice for Candida? Conjugate vaccine
Why are systemic infections difficult to diagnose? Delay in treatment contributing to > 40% mortality rate
What are some ways in which laboratory tests can be used to diagnose Candida infections? Direct microscopy (gram stain, KOH) - yeast, pseudophyphae; agar culture; blood culture; germ tube test; species-specific enzyme tests; carb utlization tests; Ag-Ab detection tests (low sensitivity / specificity); PCR (not commercially available)
Who gets affected with oropharyngeal candidiasis (thrush)? Infants, older denture-wearing adults, patients treated with antibiotics / inhaled glucocorticosteroids, patients receiving chemotherapy / radiation therapy to head & neck, patients w/ defects in cellular immunity
Why are infants susceptible to thrush? 1st exposure, underdeveloped immune system, often acquired from breast feeding (infected nipple), brith canal
Presentation of thrush in adolescents and adults "cottage cheese" patches; pseudomembranous; leukoplakia (lots of Candida growth produces grey / white pseudomembranes composed of fungi and inflammatory debris)
Presentation of thrush in geriatrics Denture stomatitis (gums, palate)
What are the four major causes of vaginitis? Lactobacillus, Candida, Gardnerella, Trichomonas
Vaginitis Common (70% of women will have one episode, 45% will have 2/more); considered normal flora in 15-25%; change in vaginal bacterial flora; decrease pH; diabetes & oral contraceptives; sexual transmission
Does Candida change the pH when causing vagnitis? NO
The most common form of mucocutaneous candidiasis Vaginitis
Vaginitis is associated with ... Increased estrogen levels (pregnancy) or use of antibiotics, glucocorticoids
Typical locations of cutaneous candidiasis Moist areas, skin folds
Cutaneous candidiasis causes ... Diaper rash, pruritic rash, nail bed & nail infection (onychomycosis, paronychia), balanitis (white patches on penis w/ burning & itching -> can spread to thighs), mastitis (lactating women w/ injured nipples), folliculitis, intertrigo (obese)
What Candida infection is most common in AIDS patients and those with hematologic malignancies? Candida esophagitis
What is the hallmark of Candida esophagitis? Odynophagia and / or dysphagia
Created by: JaneO