Systemic mycoses – Flashcards
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| T/F Endemic pathogens are contageous from person to person. |
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| False! they are found in specific geographic regions |
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| T/F Systemic mycoses that infect immunosuppressed people are saprophytes. |
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| True (saprophytes means a part of the hosts normal flora) |
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| What are "endemic" fungi? |
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| pathogens that live as saphrophytes and disseminate throughout the body found in specific geographic regions and infect healthy and immunocompromised individuals alike |
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| What are the different candida species? |
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| C. albicans, c. tropicalis, C. parapsilosis, C. glabrata |
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| What is the morphology of candida? |
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| dimorphic but primarily exists as a yeast. All can produce psuedohyphae and true hyphae except for C. glabrata |
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| What do candida look like colonized? |
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| smooth creamy white |
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| What medium causes speciation of candida? |
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| ChromAgar |
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| where are candida normally found/ |
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| everywhere |
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| Are most types of candidiasis endogenous or exogenous? |
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| endogenous (normal flora gone bad) |
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| In what form does candida cause disease? |
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| hyphal form |
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| How does candida go from normal to pathogenic? |
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| yeast cell wall glucomannans faciliatate adhesion to ECM, protease aids in invasion and changes in host innate immunity or in T cells set up for disease |
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| A functioning __________ response is critical to keeping candida from invading. |
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| TH1 |
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| Where are common infection sites of candida? |
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| mucocutaneous (oropharyngeal, vulvovaginal, skin, nail), UTI, pnuemonia, CV (endo and pericarditis), CNS infections, ocular infection, bone and joint infection, abdominal infection, hematogenous infection |
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| How do you treat candidiasis? |
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| mucosal and cutaneous are txd with topical antifungals (nystatin and terbinafine). Oral fluconazole or itraconazole (deep seated txd with oral or IV fluconazole), C. glabrata can become resistant to fluconazole so use amphotericin B + caspofungin |
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| What are the different types of aspergillis? |
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| aspergillus fumigatus, A. flavus, A. niger, and A. terreus |
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| What fungus grown in culture can look hyaline black, brown, green, yellow or white mold depending on species and growth conditions? |
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| aspergillus |
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| What does aspergillus look like microscopically? |
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| branched septate hyphae and a distinctive conidiophore (looks like an old-fashioned shaving brush). In tissue, hyphae appear as branches on a tree (dichotomous and arise at acute 45 degree angle) |
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| how does Aspergillus initiate infection? |
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| via inhalation. conidia are tiny enough to make it to alveoli and proteases and phopholipases aid spread into tissue; neutrophils and macrophages are the first line against these |
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| What is an aspergilloma? |
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| when paranasal sinuses and lower airways are colonized with aspergillus and make a fungus ball (aspergilloma) that obstructs free passage of air |
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| What tyeps of patients get aspergillomas? |
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| pts with pre-existing pulmonary conditions |
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| What types of patients get invasive pulmonary aspergillosis? |
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| neutropenic patients |
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| What do you grow aspergillos on? how do you identify it? |
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| mycological agar, characteristic conidiophore/conidia morphology |
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| How do you treat aspergillus? |
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| voriconazole and amphotericin B |
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| Name soem different species of zygomycetes? |
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| rhizopus and mucor |
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| What is the gross morphology of zygomycetes? |
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| brown wooly colonies |
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| What is the microscopic morphology of zygomycetes? |
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| broad hyaline, sparsely septate coenoccytic hyphae. A sexual conidia found within a sporangium (sporangiospores), Poreangium borne on top of sporangiophore. Root-like structures called rhizoids are present. In tissue, hyphae appear ribbon-like, aseptate or sparsely septate and non-pigmented |
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| Which species of zygomycosis is most common? |
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| rhizopus arrhizus |
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| Where are zygomycetes found and how is infection acquired? |
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| soil, decaying vegetation inhalation, ingestion, or contamination with sporangiospores from the environment |
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| Who is at risk for developing zygomycosis? |
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| immunocompromised patients, esp those with DM |
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| Describe rhinocerebral zygomycosis. |
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| acute invasive infection of the nasal cavity, paranasal sinuses, and orbit (extends into meninges and brain) Seen in pts with metabolic acidosis, esp. diabetic ketoacidosis and thsoe with leukemia |
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| What are the pulmonary zygomycosis? |
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| fungi are angioinvasive in neutropenic pts thrombosis of larger blood vessels rapidly progressive bronchopneumonia with lobar consolidation and cavitary lesions (might even seen a fungus ball) |
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| What causes Cutaneous zygomycosis? |
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| a sign of hematogenous spread (contamination of wounds) |
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| How do you diagnose zygomycetes? |
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| observe characteristic hyphae in clinical samples (scraping of nasal mucosa, BAL, infected tissue) with KOH growing the fungus from clinical samples on mycological agar (minus cyclohexamide) and ID based on conidiophore/conidia morphology (40% cultures are negative) |
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| How do you treat zygomycetes? |
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| posaconazole and amphotericin B |
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| What's a better name for pneumocystis carinii? |
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| pneumocystis jiriveci |
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| Which fungus is considered a rat pathogen? |
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| pneumocystis jiriveci |
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| What is the morphology of P. jiriveci? |
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| can exist as free trophic forms, a uninuclear sporocyst, or as a cyst containing up to 8 intracystic bodies |
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| what type of infections do pneumocystis jiriveci cause? |
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| interstitial pneumonitis with mononuclear infiltrate of plasma cells can also infect lymph nodes, spleen, bone marrow, liver, small bowel, Gu tract, eyes, ears, skin and thyroid |
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| How do you diagnose P. jiriveci? |
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| observe the organism in clinical samples (BAL, induced sputum, infected tissue) stained with a variety of histologic and cytologic stains (PAS, Geimsa, toluidine blue, etc) |
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| What is the treatment for pneumocystis jiriveci/ |
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| trimethoprim-sulfamethoxazole, pentamidine |
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| What is the morphology of cryptococcus? |
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| spherical to oval, yeast-like organism, replication occurs by budding from a narrow base, possess a thick extracellular polysaccharide capsule (glucuronoxylomannan) |
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| Where is cyrptococcus found? |
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| worldwide as a saprophyte, usually associated with soil contaminated with pigeon droppings |
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| What is the most common fungal cause of lethal infection in HIV + patients? second most common? |
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| candidiasis cryptococcosis |
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| How does cryptococcosis enter the body and cause death? |
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| aerosolized cells are inhaled into the lungs where they disseminate to the CNS |
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| What is the clinical syndrome of a crytococcus infection in healthy people? |
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| inhalation of the cells results in a mild, subclinical lung infection that is self-limiting |
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| What is the clinical syndrome of a cryptococcosis infection in a immunocompromised patient? |
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| the yeasts replicate and spread to the CNS, causing a chronic meningoencephalitis that may resemble a brain tumor, brain abscess, degenerative CNS disease, or any mycobacterial or fungal meningitis. Symptoms of headache, neck stiffness and disorientation may wax and wane but disease is ultimately fatal. Can disseminate to the eye, skin and prostate gland |
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| How do you diagnose cyrptococcosis? |
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| observing yeast forms with thick refractive capsules in clinical samples (sputum, exudates, or tissue), growth on Sabouraud's agar as white colonies of yeast or on birdseed agar as dark colonies due to melanin production. Test for capsular antigen, latex bead test |
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| How do you treat cypto coccosis? |
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| amphotericin B and flucytosine (therapy maintained in HIV patients) oral fluconazole |
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| What is the morphology of histoplasma capsulatum? |
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| thermally dimorphic at ambient temps: mold with hyaline hyphae that produces 2 types of conidia (a large thick walled spherical macroconidia with spiked walls, and oval-shaped microconidia) microconidia are phagocytized by macrophages or PMN where they then germinate into yeast |
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| Where is histoplasmosis found? |
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| endemic to ohio and mississippi river valleys, mexico, central and south america. Mold is found in high nitrogen areas (bird or bat poop)--bird roosts, caves, decaying buildings, etc. |
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| HOw do healthy people present with histoplasmosis? |
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| asymptomatic when exposure is light. heavy exposure causes a flu-like illness that resolves without treatment |
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| What are rare complications of histoplasmosis? |
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| ARDS, mediastinal fibrosis, pericarditis, arthritis 1/100,000 develop chronic pulmonary disease 1/2000 develop disseminated disease |
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| Which patients are predisposed to get chronic pulmonary disease from histoplasmosis? describe the disease. |
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| COPD apical cavitary lesions in lung and fibrosis due to host immune response |
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| Which patients are predisposed to get dissemianated disease from histoplasmosis? describe the symptoms of the disease. |
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| kids and immunosuppressed chronic- weight loss, fatigue, oral ulcers, hepatosplenomegaly subacute-same symptoms as chronic disseminated (but with fever), bone marrow involvement, adrenals, heart valves, CNS (death in 2 to 24 months) acute- septic shock like syndrome, oral and GI bleeding ulcers, meningitis, and endocarditis (death in days or weeks) |
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| How do you diagnose histoplasmosis? |
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| detection of yeasts in clinical samples, molds can be cultured but takes weeks, serological test for histoplasmin (fungal antigen), complement fixation, immuno diffusion |
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| What is the treatment for histoplasmosis? |
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| oral azoles and amphotericin B are effective for chronic and disseminated disease |
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| What is the morphology of blastomyces dermatidis? |
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| thermally dimorphic ambient- white to tan mold with round to oval conidia found on terminal hyphal branches 35-37C->blastoconidia are distinctive (broad based budding yeast) in tissue |
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| Where is blastomyces found? |
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| Ohio and Ms river valleys, decaying organic matter |
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| Which endemic fungi can infect dogs? |
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| blastomyces dermatidis |
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| T/F blastomycis dermatidis is contagious. |
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| false |
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| Infection with blastomycis dermatidis causes... |
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| mild flu-like to respiratory failure. Sub-acute or chornic pumonary blastomycosis may resemble TB or lung cancer. Hematogenous spread from lungs to skin and bones (75%), liver spleen, prostate, and CNA. Skin lesions resemble squamous cell carcinoma |
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| Describe the skin lesions associated with blastomyces dermatidis. |
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| popular, pustular, ulcerative-nodular, wart-like; painless and found on scalp, face, neck and hands, genitalia |
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| How do you diagnose blastomysis dermatidis? |
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| identify thick-walled broad based budding yeast in tissue, BAL, sputum, etc. Culture the mold from clinial material (grows yeast at 35C and mold at room temp on most mycological agar--takes a month) complement fixation, immunodiffusion |
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| How do you treat blastomyces dermatidis? |
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| amphotericin B if life-threatening itraconazole or fluconazole |
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| What is the morphology of coccidiodes immitis? |
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| dimorphic. Ambient temps= mold with vegatative hyphae that produce alternating hyaline barrel-shaped arthroconidia. at 35-37C arthroconidia become rounded into spherules (spherules mature and produce endospores) |
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| where is coccidiodes immitis found? |
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| desert= southwestern US, northern mexico and south america found in soil and has enhanced growth in bat and rodent poop cycles of rain/drought promote mold growth and subsequent arthrospore dispersal |
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| How does coccidiodes immitis get from environment to infecting a patient? |
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| arthroconidia ar ebreathed in when dry soil is disturbed (late summer/early fall) |
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| What is coccidiodis immitis infection also known as? |
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| valley fever, san joaquine valley fever, desert rheumatism |
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| Describe primary infection of coccidiodes immitis. |
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| 60% develop an asymptomatic pulmonary disease or self-limited flu-like illness 10% develop allergic response and demonstate a macular rash. Confers a strong specific immunity to re-infection |
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| Describe a secondary infection with coccidiodes immits? |
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| less than 1% of population develops in symptomatic pts after 6 wks nodular, cavitary dz in lungs (resembles TB) and lesions spread to skin, soft tissues, bone, joints and meninges |
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| How do you diagnose Coccidiodes immitis? |
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| examine endosporulating spherules in clinical samples (sputum, exudates or tisse) Mold can be cultured but not routinely done because so infectious. Complement fixation, immunodiffusion, latex particle agglutination |
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| How do you treat coccidiodes imitis infection? |
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| most don't require tx immunocompromised pts or those with symptomatic dz--> amphotericin B followed by itra- or ketoconazole therapy for a year. Oral azoles and amphotericin B are also given to chronically infected |
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| What causes vulvovaginitis by candidiasis? |
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| diabetes, pregnancy, antibiotic useage, changes in vaginal acidity |
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| Which species of zygomycetes is the most comon cause of disease? |
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| rhizopus arrhizus |
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| Describe the patient population at high risk for developing disseminated coccidiomycosis? |
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| HIV + men of filipino, african, native american or hispanic origin or people with cellular immunodeficiency |
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| What is the mortality of disseminated coccidiomycosis without tx? |
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| 90% |
