Opportunistic Fungal Infections

Question 1

Candida albicans

morphology, temperature hot & cold
p/w
cutaneous & systemic
tx

Answer 1

dimorphic
20C: pseudohyphae & budding yeast
37C: germ tubes

p/w
- oral & esophageal thrush in immunocompromised
  (neonates, steroids, DM, AIDS) 
- vulvovaginitis ( DM, ABx) 
- diaper rash
- chronic mucocutaneous candidiasis 
- endocarditis - (IV drug users) 
- disseminated candidiasis - (esp in neutropenic pts) 

tx
oral/esophageal - nystatin, fluconazole, echocandins
vaginal - PO fluconazole, topical azole
systemic - fluconazole, amphotericin B, echinocandins

Question 2

Aspergillus fumigatus

morphology
p/w
aflatoxins
Allergic bronchopulmonary aspergillosis

Answer 2

monomorphic septate hyphae; branch at 45 degree angle

aspergillomas in pre-exisiting lung cavities
immunocompromised - invasive aspergilloses, neurtrophil dysfunction

aflatoxins - a/w HCC

allergic bronchopulmonary aspergilloses
= hypersensitivity response a/w asthma & CF;
causes bronchiectasis & eosinophilia

Question 3

Cryptococcus neoformans

morphology 
found where & transmission
culture on agar? 
staining
dx test 
p/w 
tx

Answer 3

5-10 micrometers narrow budding, heavy capsule, not dimorphic

found in pigeon droppings and soil; transmitted via inhalation => hematogenous dissemination to meninges

Sabouraud agar

india ink stain ( clear halo) & mucicarmine (red inner capsule)

latex aggultination to detect polysachccharide capsule

p/w cryptococcosis, cryptococcal meningitis, cryptococcal encephalitis (soap bubble lesions in brain)

tx with amphotericin B & flucytosine => fluconazole

Question 4

Mucor & RHizopus spp

morphology
transmission
p/w
tx

Answer 4

irregular, broad, nonseptate hyphae branching at wide angles

transmission through inhalation of spores
=> fungi proliferate in blood vessels, penetrate cribiform plate
=> enter brain

H/A, facial pain, black eschar on face
can cause cavernous sinus thrombosis, frontal lobe abscess
mucormycosis in DKA and neutropenic pts

tx amphotericin B or isavuconazole

Question 5

Pneumocystis jirovecii

morphology
p/w
dx
tx

Answer 5

yeast like fungus
disc shaped yeast on methenamine silver stain

p/w PCP (pneumocystis PNA); CXR/CT ground glass opacities

dx lung Bx or lavage

TMP-SMX, pentamidine, atovaquone
dapsone = ppx only

Start ppx when CD4 <200

Question 6

Sporothrix chenckii

morphology
transmission
p/w
tx

Answer 6

dimorphic cigar shaped budding yeast, grows in branching hyphae w/ rosettes of conidia

spores introduced typically by thorn
=> local pustule/ulcer w/ nodular draining lymphatics (ascending lymphangitis)

disseminated dx in immunocompromised host

itraconazole or KI