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64 Cards in this Set
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- Back
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what conditions predispose to fungal infec?
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1. Granulocytopenia (low neutrophil count)
2. Absence of cellular immunity 3. Diabetes 4. AIDS 5. Traumatic inoculation 6. Catheters (urinary and vascular) |
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what type of granulocytopenia/neutropenia is dangerous?
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1. Neutrophil count of 500-1000/ml or less
2. Linear risk down to zero 3. Duration of neutropenia increases risk |
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what type of infections does granulocytopenia/neutropenia predispose you to?
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Candida species- fungemia
5. **Aspergillus species**- especially transplant patients with disseminated disease (esp. pneumonia) |
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when does diabetes predispose you to fungal infec?
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1. Poorly controlled dibetics
2. Ketoacidosis |
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what type of fungal infec is more common in diabetics?
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3. ** Mucormycosis**
4. Aspergillosis |
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what type of infecs can catheters predispose ppl to?
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1. Urinary bladder
2. Vascular 3. Other- eg. CNS, wound drains 4. All species of Candida |
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what clinical presentation can you get w/ someone infected by Mucor, Rhizopus or Absidia?
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Rhinocerebral: diabetics in ketoacidosis get a nasal sinus infection that spreads to the brain: Org crawls on bony plate and into brain --> kills
2. Pulmonary and systemic infections occur in transplant patients 3. Gastrointestinal (rare) |
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when you examine patient's tissue infected w/ Mucor, Rhizopus, or Absidia, what can you find?
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1. Necrotic (dead) tissue
2. Irregular, broad hyphae (5-25 microns in diameter) 3. Aseptate (coenocytic) hyphae have no cross walls 4. 90-degree-angle branching present 5. Ribbony appearance |
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what are char in culture of Mucor, Rhizopus or Absidia?
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1. Rapid growth at 25 C with abundant aerial hyphae that “lift the lid” of the petri dish (“lid-lifters”)
2. Aseptate hyphae and SPORANGIA that contain conidia 3. Hyphae may have rhizoids (rootlet-like structures) |
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when you have a culture that could be Mucor, Rhizopus, or Absidia, how do you know it's Mucor?
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has no rhizoids
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when you have a culture that could be Mucor, Rhizopus, or Absidia, how do you know it's Rhizopus?
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has rhizoids at the base of the sporangiophore
-If org has hyphae, sporangia w/ conidia, also has root strucs |
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when you have a culture that could be Mucor, Rhizopus, or Absidia, how do you know it's Absidia?
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rhizoids originate along hyphae at points between the sporangiophores
-If have root like strucs, but not underneath sporangia |
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if person has infec w/ Mucor, Rhizopus, or Absidia, how do you treat them?
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Treat underlying problem- diabetes; immunosuppressive agent
-Surgical debridment- especially rhinocerebral -Amphotericin B (IV and local irrigation) -Amphotericin B plus Caspofungin Posaconazole if AmB fails |
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what are the 3 disease types you can get w/ Aspergilla?
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Allergic aspergillosis
Fungus Ball- overgrowth in lung cavity Disseminated Aspergillosis in immune compromised patients- lung, liver, brain |
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how do you get fungus ball?
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empty space b/c tissue destroyed from tb or something like that (histoplasmosis?)
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who do you see disseminated aspergillosis in?
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transplant patients!!!
-rarely in AIDS patients |
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what are the predisposing factors to an Aspergillosis infec?
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Immune suppressive therapy
Transplantation Leukemia Corticosteroid therapy **Neutropenia** Metabolic (diabetes) |
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what are the 3 main causative agents of Aspergillosis infec?
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Aspergillus fumigatus
Aspergillus flavus Aspergillus niger |
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how do you identify Aspergillosis in tissue inspection?
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1. In sputum or tissue biopsy PMNs are present as are narrow hyphae that are septate (contain cross walls)
2. Hyphae with cross walls have parallel sides and branch at angles of 45 degrees or less |
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describe a fungus ball infec:
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1. Overgrowth of Aspergillus in an old TB or Histoplasma cavity
2. It is NOT invasive (it does not grow into living tissue) |
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how does fungus ball present when examining tissue?
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3. Tangled masses of septate hyphae present; fruiting bodies may be seen
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is fungus ball invasive?
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Not going to be invasive.. Stays right there
Can occur is anyone who had tb or histo If aspergillus disseminates, means person is immune comp |
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what type of dangerous infec can Aspergillosis cause?
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1. Aspergillus produces the enzyme elastase which allows it to invade and destroy blood vessels- the surrounding tissue then undergoes INFARCTION (death due to loss of blood supply)
2. Especially lung; also brain |
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why is it a prob if fungi in blood vessel?
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When you have extra carbs sticking out into lumen of blood vessel, that triggers coagulation and clotting of blood vessel --> that vessel dies and so does the tissue around it
If fungi penetrates vessel, same thing |
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how can an Aspergillosis infec present at the dr's if invasive?
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pulmonary embolism
cerebral infarction |
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how does Aspergillosis present in culture?
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2. Narrow, septate hyphae; few aerial hyphae and may appear granular
3. Chains of conidia are produced on a “fruiting head” also called an aspergillum -grows on agar and w/i agar |
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how do you tell the difference in culture b/w A. flavus and A. fumigatus?
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1. A. fumigatus: green/brown
colonies; conidia cover only 1/2 of the vesicle; uniserate (phialides on vesicle) 2. A. flavus: yellow/brown colonies; conidia are circumferential; biserate or uniserate; conver entire fruiting head |
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what's the most common cause of aspergillosis infec in humans?
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A. fumigatus
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how can you tell the difference in culture b/w A. niger and A. tereus?
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A. niger: Colonies with black dots
on white backgroung (peppered); conidia are circumferential; biserate 4. A. tereus: Cinnamon colored colonies; hemispherical vesical with biserate phialides; may have aleurioconidia |
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what does biserate mean?
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2 stacks of conidia
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what's the treatment for Aspergillosis?
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Treat the underlying condition
*Voriconazole Amphotericin B Itraconazole (intravenous) Caspofungin |
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what's the clinical presentation of Candidiasis?
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1. Mucocutaneous (thrush); oral
and vaginal are most common 2. Cutaneous 3. Systemic or disseminated with multiple organ involvement and fungemia; immune compromised patients |
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what's the most common opportunistic fungi infec?
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Candidiasis
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what is thrush?
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overgrowth of candidiasis
*if AIDS patient it can spread to your esophagus candida -if get esophagitis, don’t live long after that. It’s a reflection of their overall immune status |
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what are predisposing factors for Candidiasis infec?
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1. Pregnancy and cystitis
2. Diabetes 3. Cancer chemotherapy 4. Broad-spectrum antibiotics destroy the normal flora 5. AIDS; Candida esophagitis- poor prognosis 6. Urinary or vascular catheters |
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what are the char of Candida albicans?
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-Budding yeast
-Pseudohyphae in tissue and on cornmeal -Over 90% are Germ Tube-(+) -Round or oval hyaline, budding yeasts are 3-5 microns in size (blastoconidia) -Elongate yeasts that bud but do not pinch off are called pseudohyphae |
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How does Candida present in culture?
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3. Incubation in human or animal
serum at 37 C for 2-4 hours usually shows Germ Tubes 4. Pseudohyphae and CHLAMYDOCONIDIA on cornmeal; also blastoconidia at constriction points PNA- FISH: MOLECULAR TEST |
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how do you treat Candidiasis?
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Topical agents for superficial infections
Life-threatening: Amphotericin B, voriconazole, itraconazole |
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what sp. causes Cryptococcosis?
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Cryptococcus neoformans
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what are the symptoms of Cryptococcus?
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1. Early- pulmonary with cough and weight loss
2. Meningitis with headache, vomiting, and nuchal rigidity (stiff neck); 100 % fatal if untreated 3. Disseminated; in AIDS |
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what are the char of Cryptococcus neoformans?
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1. Budding yeast with CAPSULE
2. Highly variable in size |
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how does Cryptococcus neoformans present when examined under the microscope?
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1. Sputum or CSF shows budding
yeasts of variable size surrounded by a halo (capsule) 2. 3-20 microns in size- usually a “narrow-based bud” 3. Little tissue inflammation 4. Pleomorphic yeasts (variable in size) |
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how does Cryptococcus neoformans present in culture?
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1. Slimy colonies in 48-72 hours
2. Killed by cyclohexamide 3. Urease (+) 4. MELANIN production on birdseed (niger seed) agar 5. No fermentation 6. Assimilation tests useful |
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where can you find Cryptococcus neoformans?
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1. Source in nature is unknown
2. Yeast can be found commonly in soil enriched by pigeon droppings |
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what's the route of infection of Cryptococcus neoformans?
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respiratory- pneumonia, then fungemia, then meningitis
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what's the tx for Cryptococcus neoformans?
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Amphotericin B or fluconazole
Voriconazole 5-Fluorocytosine (5-FC) if meningitis present (penetrates to CSF) |
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Describe Candida (Torulopsis) glabrata:
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yeasts only no pseudohyphae; Urinary tract infections
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describe Geotrichum-
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arthroconidia
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describe Trichosporon-
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oval arthroconidia
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describe Rhodotorula-
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capsule; orange
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describe Malassezia-
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-tiny yeast; needs olive oil for growth; prematurity, hyperalimentation
-can cause life threatening infecs in newborns and patients on hyperalimentation ( sick patients who can’t eat and get nutrients thru IV) |
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describe Dematiaceous Fungi (Phaeohyphomycoses):
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Pigmented (natural brown color) and septate hyphae
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who's predisposed to Dematiaceous Fungi (Phaeohyphomycoses) infections?
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Traumatic wounds and lacerations
3. Immune compromised |
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what stains do you use for dematiaceous fungi?
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H & E
GMS |
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who's at risk for a Pneumocystis jiroveci (carinii) infec?
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AIDS and post-transplant
immunosupression; also “treated” leukemia patients |
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describe Pneumocystis jiroveci (carinii) char:
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. Giemsa stain on lung fluid (BAL) shows TROPHOZOITES inside cysts- as many as 8
3. CYSTS only seen on GMS 4. Does not grow on fungal media in the laboratory |
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what stains are used to see Pneumocystis jiroveci (carinii)?
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H & E
GMS giemsa |
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what's the tx for Pneumocystis jiroveci (carinii)?
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Trimethoprim sulfamethoxazole (Septra)
Pentamidine |
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how long does it take aspergillus to grow in culture?
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1. Mold usually grows within 24-48
hours at 25 C |
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how long does it take Candida yeast to grow?
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1. Yeast colonies grow within 24
hours at 37 C or at 25 C |
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what can you grow Candida on?
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2. Growth on blood agar or most
fungal media |
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how can you determine candida speciation?
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5. Candida speciation by sugar
fermentation (acid and/or gas production) and assimilation (growth using only 1 sugar as carbon source) |
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what test do you use to see if you have Cryptococcus neoformans?
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3. India Ink shows capsule
4. **Latex Agglutination is a better test- better sensitivity and better specificity than the India Ink |
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how do you visualize Cryptococcus neoformans?
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5. Mucin stain shows capsule
6. GMS and Giemsa stains also |
