Mycology random facts

Question 1

cryptococcus usu seen in what type of patients?

Answer 1

majority have problem with cell mediated immunity (but can affect anyone)

Question 2

cryptococcus

Answer 2

pigeon and kowala poo, soil

• -inhalation –> hematog spread –> dissemination
• 5-10um
• havily encapsulated

Question 3

cyptococcal meningitis

Answer 3

-prompt tx (100% fatal without)
-hematog spread from apparent lung infx
-NON-inflammatory –> do not get influx of PMNs
-Obstruction of CSF flow and INCREASE ICP due to cells clogging up plumbing
Tx: amphotericin B +flucytosine, f/u with flucon

Question 4

rapid diagnostic test for cryptococcus

Answer 4

CRAG (cryptococcal antigen test)–> looks for surface antigen

• high sens/spec
• quick and rapid test, cheap
• urine, serum, CSF

Question 5

candida

Answer 5

• part of normal flora
• dimorphic (buds at 20, germ tubes at 37)
• problem in ICUs/hospitals
• major cause of bacteremia via catheters, trachs
• can travel to multiple organs

Question 6

diagnostic tests for candida (tl:dr- its a bad test)

Answer 6

1,3-beta-D-glucan

• NOT specific for candida
• binds cell wall component of candida and a lot of other things
• NOT cyrto, mucorales, blastomyces derm
• has a lot of false positives

Question 7

aspergillus

Answer 7

• mold
• acute angle (45 deg), septate, hyphae
• common in the air, can get into AW easily
• casue dz in vulnerable pops
• propensity to grow in cavitary lesions (old TB)
• “halo sign” on imaging
• causes dz in pt with neutropenia, CGD

Question 8

hyphae

Answer 8

-grows TOWARDS food source

Question 9

aspergillus fumigatus

Answer 9

-responsible for majority of dz
narrow hyphae
-45 degree branching
-septate 
- conidiophores

Question 10

diagnostic test for aspergillus

Answer 10

• look for galactomanna (crosslinks wall)
• has cross reactivity, no specific
• b-d-galactan –> same test used for candida (not good)

Question 11

C. neoformans morphology (uworld)

Answer 11

yeast form
round/oval
HEAVILY encapsulated cells with narrow base buds

Question 12

c neo virulence (uworld)

Answer 12

thick polysac capsule

Question 13

c neoformans epi (uworld)

Answer 13

• soil and pigeon poop
• opp infx
• resp transmission

Question 14

c neoformans infx

Answer 14

primary= lung
most common= meningoencephalitis
*can show hematogenous dissemination

Question 15

c neoformans dx (uworld)

Answer 15

india ink of CSF (halo cells)
latex agglutination for polysach capsule (CSF)
culture on Sabouraud’s agar
methenamine silver (GMS) stain or mucicarmine (red)

Question 16

c neo tx (uworld)

Answer 16

amphotericin B and flucytosine (acute meningitis)

*fluconozole for lifelong prophylaxis

Question 17

CNS infection in HIV+ patient is likely…..

Answer 17

cryptococcus neo. most common cause of fungal meningitis

Question 18

mucorales

Answer 18

mold

• NONseptate hyphae, 90 degree angles
• MUCORMYCOSIS –> pt with DKA, DM (likes high glucose)
• pt with hemachromatosis, or treated with deferoxamine –> likes iron
• FAST growth

Question 19

rhinoorbitalcerebral mucor

Answer 19

gains entry through cribiform plate, gets into frontal lobes

Question 20

3 major dz of aspergillus

Answer 20

1) allergic bronchopulmonary aspergillosis (ABPA) –> type I hypersensitivty, assoc with asthma (increased IgE, eos) and CF
2) Angioinvasive aspergillosis –> immunocomp patients/ CGD, disseminates to heart, kidney and brain (ring enhanced lesions). Tx= AmphoB
3) aflatoxins –> HCC

Question 21

Dematiaceous moulds

Answer 21

black molds

• soil saprophytes
• DIRECT innoculation
• melanin (makes it black) –> bad.
• can disseminate –> can cause meningitis

Question 22

dimorphic fungi (geographic fungi)

Answer 22

• use phenotypic switching to grow in human body –> THERMAL DIMORPHISM
• cold= mold
• yeast= heat (body)
• histoplasmosis
• blastomycosis
• coccidio (spherule, not yeast)
• paracoccidio

Question 23

blastomycosis

Answer 23

• eastern US, ohio river valley, great lakes
• central america
• inhaled
• Blasto Buds Broadly (cannon balls)
• same size as RBC
• 8-15um
• disseminates in IC –> to skin and bone (general lee)

Question 24

is blastomyces in CO?

Answer 24

dogs can get it from praire dogs

Question 25

What are the two most common forms of dz of blastomyces?

Answer 25

PULMONARY --> (hematogenous dissemination) --> CUTANEOUS BLASTO -cutaneous can be confused for skin cancer

Question 26

what type of immune response do you see in blastomyces? what type of immune response do you generally see for fungi?

Answer 26

pyogranulomatous response fungi= cell mediated

Question 27

coccidiomycoses

Answer 27

-grows in SPHERULES filled with endospores -alternatin arthroconidia -BIG 50-100 um -southwestern US, Cali, DESERTS -

Question 28

dz manifestations of coccidiomycoses

Answer 28

- PNA (turns cavitary) , meningitis - hemog dissem to skin and bone - san jaquin valley fever - "desert bumps" --> erythema nodosum - desert rhuematism --> arthralgias ***fever, cough, arthralgia

Question 29

Serology of coccidioides

Answer 29

If you have ab to coccidio, you HAVE INFX early: immunodiffusion >1 mo --> Complement fixation (CF) -CF titer predicts extrapulm dz -CF titer tells if tx is working

Question 30

histo

Answer 30

mississippi and ohio river valleys - ANYTHING to do with birds - resp tract transmition - Histo Hides in macrophages - MUCH smaller than RBC - rapid serum, urine antigen

Question 31

dz from histo

Answer 31

PNA - calcifications - late chronic looks like TB - may see elevated inflamm markers (LDH, ferritin, non specific) - targets RES --> HSM

Question 32

do you get blood cultures for histo? what kind?

Answer 32

Takes weeks to grow. do LYSIS CENTRIFUGATION. Spin it down, then try to culture it

Question 33

how long do you treat these disseminated diseases?

Answer 33

like years.

Question 34

sporothrix schenckii

Answer 34

- dimorphic assoc with ZOONOTIC transmission --> dogs and cats - cigar shaped - budding yeast - grows in branching hyphae with rosettes of conidia - lives on vegetation --> "ROSE GARDER dz" - ascending lymphangitis

Question 35

how do you usually get sporothricosis? how do you treat sporothricosis?

Answer 35

DIRECT innoculation (roses). itraconazole or potassium iodide

Question 36

sporothrix (slide from class)

Answer 36

aggriculture children, men world wide + hyperendemic (peru) zoonotic

Question 37

preogression of sporo

Answer 37

skin ulcer --> ascending lymphangitis --> these areas up the lymph chain become necrotic

Question 38

does sporo disseminate? is it common? what are risk factors?

Answer 38

yes, uncommon where: joint, bone, lung, meninges who: EtoH, DM, late HIV, COPD

Question 39

paracoccidiodies

Answer 39

- rare - latin america - sub tropical, mountainous climates where coffee can grow - agg workers on coffee plantations - LONG incubation (decades) - adults - males - can present like COPD

Question 40

why would culture of open skin wounds be discouraged?

Answer 40

they generally just grow normal skin flora