Kozel: Opportunistic Mycoses Flashcards
List 5 opportunistic mycoses
Candidiasis Cryptococcosis Aspergillosis Mucormycosis Pneumocystosis
Where are Candida albicans and Candida spp. normally found?
in the skin - particularly in health care workers
in the GI tract from the mouth to the rectum
in the female GU tract
What is the most common species of Candida?
C. albicans
What is the morphology of Candida albicans and Candida spp?
primarily yeasts
true hyphae
pseudohyphae
What do Candida spp form?
germ tubes *hypha emerging from a yeast-like structure
Most infections with Candida are endogenous. What does this mean?
normal commensal flora takes advantage of an opportunity to cause infection
What does Candidiasis cause at mucous membranes?
thrush
candida esophagitis *often in AIDS
vaginitis
What % of normal women have at least one episode of vaginitis causes by Candida?
75%
What organs/organ systems can Candida affect?
CNS pneumonia - lungs bones and joints endocarditis urinary tract abdominal hematogenous disseminated candidiasis - in the blood
What type of infection does candidiasis cause?
major nosocomial infection
**3rd most common blood stream infection
What are the general risk factors for invasive candidiasis?
hematologic cancer neutropenia GI surgery premature infants patients older than 70
What are some special risk factors for invasive candidiasis?
time spent in ICU
central venous catheter
colonization at multiple sites
number of antibiotics given
How would you diagnose candidiasis?
- scrape mucosal and cutaneous lesions and use KOH to see if yeast is present
- histopathology
- budding yeast-like forms and pseudohyphae
- look for germ tube formation
In all cases, look for budding yeast and pseudohyphae
What are three sources of tissue that you could culture to look for candida?
- scrapings from lesions
- blood *only 50% positive
- tissue or normally sterile body fluids
Candida can grow on standard mycologic media. What other medium might you use?
selective chromogenic medium
How can you CONFIRM a diagnosis of Candida?
germ tube formation - production of germ tubes when grown on serum
What is used to treat oral thrush caused by candida?
topical creams and lotions: nystatin or clotrimazole (azole)
oral systemic therapy: fluconazole or other azoles
prophylactic fluconazole in AIDS
What is used to treat esophagitis caused by candida?
oral systemic therapy: fluconazole
**topical therapy usu fails
What can be used to treat uncomplicated Candida vaginitis? What about recurrent Candida vaginitis?
over the counter topical azoles/oral azoles;
remove or treat causal factor - or induce course of azole followed by long-term maintenance regimen
How can you avoid cadidiasis?
avoid broad spectrum antibiotics!!
be cautious with catheter care
infection control
What are some ways in which you could remove the source of infection for candida?
remove or change the catheter
drain abscesses
List three antifungal agents used for candida
Polyene **AmB (but watch out for nephrotoxicity)
Triazole **esp fluconazole
Echinocandin
Where is Aspergillus spp. found?
everywhere! in air, soil, decaying vegetation
hospitals - air, water, potted plants
What is the morphology of Aspergillus spp? What does it look like?
branched septate hyphae;
conidial heads with spheric conidia
What are two diseases caused by Aspergillus?
allergic bronchopulmonary aspergillosis - type 2 reaction
aspergilloma - balls of fungus in the lungs
How do invasive syndromes begin with Aspergillus? What are they syndromes associated with?
inhalation of conidia (spores) into lungs; angioinvase (can get into blood vessels and disseminate); associated with immunosuppression - organ/stem cell transplants, neutropenia, corticosteroids or other immunosuppressive therapies
What toxin does Aspergillus produce?
aflatoxin
Invasive aspergillosis is very common after (blank)
transplantation
What do you look for to diagnose Aspergillosis?
look for invasion of hyphae - septate hyphae with acute-angle branching
What else could you do to diagnose aspergillosis?
tissue biopsy - can’t use blood culture
**sometimes too risky in immunosuppressed patients
radiology for invasive pulmonary aspergillosis
biomarkers
What are some biomarkers you would look for in aspergillosis?
beta-glucan - non-specific fungal marker
galactomannan in serum
How can you prevent aspergillosis?
patient isolation
HEPA filters
positive pressure
pozaconazole prophylaxis for very high risk patients
What is the primary drug used for treatment of aspergillosis?
voriconazole (triazole - blocks ergosterol synthesis)
Where would you find mucorales and mucormycosis?
in the environment - particularly decaying bread, fruit, vegetable matter, soil
What is the morphology of mucorales and mucormycosis?
coenocytic hyphae - with few septae - multinucleate
saclike fruiting structure with internal spores (sporangium with internal sporangiospores)
What is the most common genera of mucorales that causes disease?
Rhizopus
How do you get infected with mucormycosis?
inhalation of spores
What does mucormycosis do to blood vessel walls?
causes necrosis - angioinvasive (invades blood vessels)
What are some risk factors for infection by mucormycosis?
neutropenia
transplants (immunocompromised)
diabetes or any metabolic acidosis
deferoxamine (chelation) therapy to remove toxic amounts of iron (fungi use deferoxamine)
What are 4 diseases that mucormycosis might cause?
- rhinocereberal (assoc. w diabetes mellitus)
- pulmonary infection
- cutaneous infection
- disseminated infection
How would you diagnose mucormycosis?
biopsy, swabs, culture etc
in histopath, look for broad, empty, thin-walled mostly aseptate hyphae (coenocytic - no septal divisions)
What biomarkers would you want to be NEGATIVE if you were looking to confirm a diagnosis of mucormycosis?
Beta-glucan and galactomannan
**these are positive for aspergillosis, but DON’T WORK FOR THIS ONE
What is the overall drug of choice for mucormycosis?
Amphotericin B
**azoles don’t work
What is the problem with mucormycosis? So what can be done?
resistance to many antifungals (azoles, flucytosine, echinocandins) - so reverse underlying condition, maybe via surgical resection
**overall, poor prognosis
What would you look for in a slide of invasive pulmonary aspergillosis?
BRANCHING, SEPTATE HYPHAE
What is the morphology of Cryptococcus neoformans?
encapsulated yeast
Where is Crytococcus neoformans found?
in PIGEONS and trees
What do you look for in the immunoassay for Cryptococcus neoformans?
capsular antigen
**use a drop of blood
What are some diseases caused by Cryptococcus neoformans?
pulmonary cryptoccosis
crytococcal meningitis
opportunistic - AIDS and other immunosuppression
**kills tons of people in Africa :(
What are the two forms of pneumocystis jirovecii?
tropic, sporocyst and cyst forms
**cysts are empty, collapsed balls
What is unique about the life cycle of pneumocystis jirovecii?
sexual AND asexual life cycle
human is the reservoir
What diseases are caused by Pneumocystis jirovecii?
likely infects most normal humans
esp those with AIDS, immunosuppression, infants
causes interstitial plasma cell pneumonitis
