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Systemic mycoses
9.6 at 1pm by Dr. Hobden
76
Microbiology
Professional
09/07/2011

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Cards

Term
T/F Endemic pathogens are contageous from person to person.
Definition
False! they are found in specific geographic regions
Term
T/F Systemic mycoses that infect immunosuppressed people are saprophytes.
Definition
True (saprophytes means a part of the hosts normal flora)
Term
What are "endemic" fungi?
Definition
pathogens that live as saphrophytes and disseminate throughout the body
found in specific geographic regions and infect healthy and immunocompromised individuals alike
Term
What are the different candida species?
Definition
C. albicans, c. tropicalis, C. parapsilosis, C. glabrata
Term
What is the morphology of candida?
Definition
dimorphic but primarily exists as a yeast. All can produce psuedohyphae and true hyphae except for C. glabrata
Term
What do candida look like colonized?
Definition
smooth creamy white
Term
What medium causes speciation of candida?
Definition
ChromAgar
Term
where are candida normally found/
Definition
everywhere
Term
Are most types of candidiasis endogenous or exogenous?
Definition
endogenous (normal flora gone bad)
Term
In what form does candida cause disease?
Definition
hyphal form
Term
How does candida go from normal to pathogenic?
Definition
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
Term
A functioning __________ response is critical to keeping candida from invading.
Definition
TH1
Term
Where are common infection sites of candida?
Definition
mucocutaneous (oropharyngeal, vulvovaginal, skin, nail), UTI, pnuemonia, CV (endo and pericarditis), CNS infections, ocular infection, bone and joint infection, abdominal infection, hematogenous infection
Term
How do you treat candidiasis?
Definition
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
Term
What are the different types of aspergillis?
Definition
aspergillus fumigatus, A. flavus, A. niger, and A. terreus
Term
What fungus grown in culture can look hyaline black, brown, green, yellow or white mold depending on species and growth conditions?
Definition
aspergillus
Term
What does aspergillus look like microscopically?
Definition
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)
Term
how does Aspergillus initiate infection?
Definition
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
Term
What is an aspergilloma?
Definition
when paranasal sinuses and lower airways are colonized with aspergillus and make a fungus ball (aspergilloma) that obstructs free passage of air
Term
What tyeps of patients get aspergillomas?
Definition
pts with pre-existing pulmonary conditions
Term
What types of patients get invasive pulmonary aspergillosis?
Definition
neutropenic patients
Term
What do you grow aspergillos on? how do you identify it?
Definition
mycological agar, characteristic conidiophore/conidia morphology
Term
How do you treat aspergillus?
Definition
voriconazole and amphotericin B
Term
Name soem different species of zygomycetes?
Definition
rhizopus and mucor
Term
What is the gross morphology of zygomycetes?
Definition
brown wooly colonies
Term
What is the microscopic morphology of zygomycetes?
Definition
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
Term
Which species of zygomycosis is most common?
Definition
rhizopus arrhizus
Term
Where are zygomycetes found and how is infection acquired?
Definition
soil, decaying vegetation
inhalation, ingestion, or contamination with sporangiospores from the environment
Term
Who is at risk for developing zygomycosis?
Definition
immunocompromised patients, esp those with DM
Term
Describe rhinocerebral zygomycosis.
Definition
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
Term
What are the pulmonary zygomycosis?
Definition
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)
Term
What causes Cutaneous zygomycosis?
Definition
a sign of hematogenous spread (contamination of wounds)
Term
How do you diagnose zygomycetes?
Definition
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)
Term
How do you treat zygomycetes?
Definition
posaconazole and amphotericin B
Term
What's a better name for pneumocystis carinii?
Definition
pneumocystis jiriveci
Term
Which fungus is considered a rat pathogen?
Definition
pneumocystis jiriveci
Term
What is the morphology of P. jiriveci?
Definition
can exist as free trophic forms, a uninuclear sporocyst, or as a cyst containing up to 8 intracystic bodies
Term
what type of infections do pneumocystis jiriveci cause?
Definition
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
Term
How do you diagnose P. jiriveci?
Definition
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)
Term
What is the treatment for pneumocystis jiriveci/
Definition
trimethoprim-sulfamethoxazole, pentamidine
Term
What is the morphology of cryptococcus?
Definition
spherical to oval, yeast-like organism, replication occurs by budding from a narrow base, possess a thick extracellular polysaccharide capsule (glucuronoxylomannan)
Term
Where is cyrptococcus found?
Definition
worldwide as a saprophyte, usually associated with soil contaminated with pigeon droppings
Term
What is the most common fungal cause of lethal infection in HIV + patients? second most common?
Definition
candidiasis cryptococcosis
Term
How does cryptococcosis enter the body and cause death?
Definition
aerosolized cells are inhaled into the lungs where they disseminate to the CNS
Term
What is the clinical syndrome of a crytococcus infection in healthy people?
Definition
inhalation of the cells results in a mild, subclinical lung infection that is self-limiting
Term
What is the clinical syndrome of a cryptococcosis infection in a immunocompromised patient?
Definition
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
Term
How do you diagnose cyrptococcosis?
Definition
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
Term
How do you treat cypto coccosis?
Definition
amphotericin B and flucytosine (therapy maintained in HIV patients)
oral fluconazole
Term
What is the morphology of histoplasma capsulatum?
Definition
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
Term
Where is histoplasmosis found?
Definition
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.
Term
HOw do healthy people present with histoplasmosis?
Definition
asymptomatic when exposure is light. heavy exposure causes a flu-like illness that resolves without treatment
Term
What are rare complications of histoplasmosis?
Definition
ARDS, mediastinal fibrosis, pericarditis, arthritis
1/100,000 develop chronic pulmonary disease
1/2000 develop disseminated disease
Term
Which patients are predisposed to get chronic pulmonary disease from histoplasmosis? describe the disease.
Definition
COPD
apical cavitary lesions in lung and fibrosis due to host immune response
Term
Which patients are predisposed to get dissemianated disease from histoplasmosis? describe the symptoms of the disease.
Definition
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)
Term
How do you diagnose histoplasmosis?
Definition
detection of yeasts in clinical samples, molds can be cultured but takes weeks, serological test for histoplasmin (fungal antigen), complement fixation, immuno diffusion
Term
What is the treatment for histoplasmosis?
Definition
oral azoles and amphotericin B are effective for chronic and disseminated disease
Term
What is the morphology of blastomyces dermatidis?
Definition
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
Term
Where is blastomyces found?
Definition
Ohio and Ms river valleys, decaying organic matter
Term
Which endemic fungi can infect dogs?
Definition
blastomyces dermatidis
Term
T/F blastomycis dermatidis is contagious.
Definition
false
Term
Infection with blastomycis dermatidis causes...
Definition
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
Term
Describe the skin lesions associated with blastomyces dermatidis.
Definition
popular, pustular, ulcerative-nodular, wart-like; painless and found on scalp, face, neck and hands, genitalia
Term
How do you diagnose blastomysis dermatidis?
Definition
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
Term
How do you treat blastomyces dermatidis?
Definition
amphotericin B if life-threatening
itraconazole or fluconazole
Term
What is the morphology of coccidiodes immitis?
Definition
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)
Term
where is coccidiodes immitis found?
Definition
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
Term
How does coccidiodes immitis get from environment to infecting a patient?
Definition
arthroconidia ar ebreathed in when dry soil is disturbed (late summer/early fall)
Term
What is coccidiodis immitis infection also known as?
Definition
valley fever, san joaquine valley fever, desert rheumatism
Term
Describe primary infection of coccidiodes immitis.
Definition
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
Term
Describe a secondary infection with coccidiodes immits?
Definition
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
Term
How do you diagnose Coccidiodes immitis?
Definition
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
Term
How do you treat coccidiodes imitis infection?
Definition
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
Term
What causes vulvovaginitis by candidiasis?
Definition
diabetes, pregnancy, antibiotic useage, changes in vaginal acidity
Term
Which species of zygomycetes is the most comon cause of disease?
Definition
rhizopus arrhizus
Term
Describe the patient population at high risk for developing disseminated coccidiomycosis?
Definition
HIV + men of filipino, african, native american or hispanic origin or people with cellular immunodeficiency
Term
What is the mortality of disseminated coccidiomycosis without tx?
Definition
90%
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