Flashcards in Opportunistic Mycoses-Kozel Deck (42)
What are the important opportunistic mycoses?
What is the morphology of candida?
also pseudohyphae & true hyphae (less common)
forms germ tubes
What are germ tubes?
take yeast & put it in serum & throw it in an incubator.
makes a hyphae that is called a germ tube
a way to identify candida in the lab
Where is candida normally found?
totally normally found in humans
skin--esp of health care workers
What are the different species of candida? Which is most common?
Most common: C. albicans
w/ the wide use of fluconazole starting to see disease form from other types.
When candidiasis is a mucous membrane infection--how does it present?
takes normal flora & makes an opportunistic infection
thrush in the oral cavity
vaginitis (75% women)
There can also be cutaneous candidiasis syndromes. What do these involve?
involve moist tissues
When candidiasis has deep organ involvement--which organs does it involve? Which of these is the biggest concern?
bone & joint
hematogenous disseminated candidiasis (invasive-biggest concern b/c the organism gets into the blood of a sick person)
Describe how invasive candidiasis is a major nosocomial infection.
3rd most common blood stream infection
seen in hospitals
this type of infection costs a lot!!
What are the general risk factors for invasive candidiasis?
patients older than 70 yrs
What are some specific risk factors for invasive candidiasis?
Time spent in ICU
Central venous catheter
Colonization at multiple sites-if it is at more parts of your body
Number of antibiotics given-b/c antibiotics knock down normal flora
What is involved in the direct examination of candidiasis?
Scrapings of mucosal or cutaneous lesions - KOH mount
Budding yeast-like forms and pseudohyphae
How do you take a culture for diagnosis of candidiasis?
samples include scrapings, blood, or tissue. BUT blood is only pos 50% of the time & tissue is difficult to do in a sick patient.
grow it on standard mycologic media
use selective chromogenic medium--different species grow different colors
**confirmed by germ tube formation when grown in serum
So...you have a pt in the ICU with a fever of unknown origin. You culture & put them on antibiotics. They don't respond & culture is neg. Then what?
might be a fungal infection
it won't show up in blood culture
maybe just put them on antifungals
How do you treat oral thrush-mucocutaneous candidiasis?
topical creams w/ nystatin or clotrimazole
oral systemic therapy w/ azoles
If you have AIDS: prophylactic fluconazole
What is nystatin similar to?
similar to amphotericin B. It is a polyene.
HOw do you treat esophagitis-mucocutaneous candidiasis?
topic therapy won't work
oral systemic therapy-fluconazole
How do you treat uncomplicated candida vaginitis-mucocutaneous candidiasis?
OTC topical azoles
How do you treat recurrent candida vaginitis?
treat causal factor if present-HIV, uncontrolled diabetes, antibacterials, hormone replacement therapy
use strong azole & maintenance azole, like fluconazole
How do you prevent deep-seated candidiasis?
avoid broad spectrum antibiotics
be meticulous with your catheter
If you have deep-seated candidiasis what do you do?
remove the source of the infection, the catheter, drain abscesses
use anti fungal agents
Polyene-amphotericin B. Don't forget about nephrotoxicity, tho!
What is the morphology of aspergillus?
branched septate hyphae
conidial heads with spheric conidia
Where do you find aspergillus?
everywhere in air, soil, decaying vegetation
esp in hospitals
There are 19 disease producing species of aspergillus. What are the 4 most common? List in order of most to least common.
What are some diseases caused by aspergillum?
allergic bronchopulmonary aspergillosis-th2 response
aspergilloma-fungus ball in lung
invasive syndromes--begin in lungs, angioinvasive...happens with immunosuppression-->causes: invasive pulmonary aspergillosis or disseminated infection
Which toxin does aspergillus release in food etc?
Is aspergillosis an issue with people who receive bone marrow transplants?
7% of BT recipients develop invasive aspergillosis. 1/3 of those die.
How do you diagnose aspergillosis?
histopath showing invasion with hyphae (includes special stains)
culture of biopsy, but can be risky in sick pt
blood cultures not really helpful
**Note: difficult to interpret cultures from non-sterile sites b/c these things are everywhere!
radiology with halo sign
Which biomarkers are helpful in diagnosing aspergillosis?
beta glucan-nonspecific fungal marker
immunoassay for galactomannan in serum
How do you prevent aspergillosis?
pozaconazole prophylaxis for high risk pts
How do you treat aspergillosis?
can also use amphotericin B, other triazoles, echinocandins
WHat is the morphology of mucorales?
coenocytic hyphae, few septa, multinucleated
saclike fruiting structures-called sporangia w/ internal sporangiospores
Where do you find mucorales?
everywhere in the environment, esp in decaying organic substrates like food & soil
Is infection w/ mucorales common? What are the 4 most important genera (most common-->least common)?
infection is rare. acquired by inhalation or cutaneous or percutaneous inoculation of spores
T/F Mucormycosis involves an angioinvasive mucorales.
True. It invades blood vessels & causes necrosis of vessel walls.
WHat are risk factors for mucormycosis?
Solid organ/hematopoietic stem cell transplant
Diabetes or metabolic acidosis
Deferoxamine (chelation) therapy to remove excess iron – fungus uses deferoxamine as a xenosiderophore
**mucor actually feeds off of the chelator!
What are some clinical diseases that can result from mucormycosis?
Rhinocerebral – associated with diabetes mellitus
How do you diagnose mucormycosis?
samples--biopsy, swabs, not really blood cultures
histopath will show broad, empty, thin walled, mostly aseptate hyphae
What would a culture of mucormycosis show?
rapidly grown in standard mycologic media
see sporangium & sporangiospores
What are the biomarkers that can be sued to check for mucormycosis?
there aren't any!
beta glucan & galactomannan will both come up negative.
How do you treat mucormycosis?
resistant to antifungals
surgical resection of infected area
**sometimes the bad forms of this begins as a sinus tract infection