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WVSOM - Candida
Candida
| Question | Answer |
|---|---|
| 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
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