Micro: Opportunistic Mycoses in AIDS Flashcards
What is the most common fungal inf in AIDS pts?
oropharyngeal candidiasis (thrush)
What is the microbiology of candida?
grows slowly as yeast in culture
oval budding cells in culture and blood
branching pseudohyphae in some species
can stain gram+ but are much larger than bacteria
What are the symptoms of candidiasis in HIV?
altered taste, odynophagia, retrosternal pain, pseudomembranous thrush (can be scraped away), erythematous oral candidiasis, esophagitis
What are important risk factors for candidemia and invasive candidiasis?
central venous lines, invasive procedures, broad spectrum abx
NOT more common in HIV, only mucosal inf
How is candidiasis diagnosed?
clinical presentation
maybe endoscopy to rule out other sources
KOH prep - budding yeast and pseudohyphae
biopsy of oral lesions, esp if no response to Tx
culture not usually helpful b/c it is normal flora, culture of blood can confirm disseminated
What is the general treatment for candidiasis?
Fluconazole, oral or IV - resistance not uncommon
treat underlying HIV
What are important implications for candidiasis in HIV?
more common as CD4 falls, but can occur when higher
recurrent or resistant thrush is indication to start HIV treatment
esophageal candidiasis = AIDS defining condition
What is the prevention of candidiasis?
prophylaxis w fluconazole not recommended due to resistance
What is the microbiology/epidemiology of c. neoformans?
encapsulated yeast
worldwide distribution, soil and pigeon droppings
doesn’t infect birds
serotypes based on capsular agglutination rxns - A, B, C, or D (A and D most common in AIDS)
family includes c. gattii
What is the pathogenesis of crypto?
portal of entry is lungs (also needle stick entry, transplant)
antiphagocytic capsule - prevents phagocytosis, depeletes complement, interferes with cell/cytokine response, prevents drainage of CSF
melanin made by yeast = virulence factor, tolerates oxidative stress
What are the clinical manifestations of crypto?
meningitis - most common, signs usually -
increased ICP
pneumonia
How is crypto diagnosed?
cryptococcal antigen in CSF and serum - detects part of capsule
smooth, yellow-tan colonies
Who are the c. gattii hosts?
mostly in pts with “normal” immune system - may be subclinical problem
can be in HIV+
What is the treatment of crypto?
amphoterecin B + flucytosine (5-FC)
oral regimens NOT preferred
in AIDS, IV for two weeks followed by oral maintenance
ampho B can reversibly raise creatinine
resistance rare unless using fluconazole
elevated CSF pressure - no meds, lumbar puncture
What is the maintenance/prophylaxis for crypto?
maintenance: start w fluconazole at higher doses for 8-10 wks
continue at lower doses til CD4 over 200
primary prophylaxis NOT recommended
What are the key points about histo?
ohio river valley, southeast (inc Dallas), in soil fertilized by bird or bat poop, inf through inhalation of spores
present intracellularly in phagocytic cells
acute and chronic pneumonias
no primary prophylaxis
What are the key points about cocci?
endosporulating spherules in tissue, highly infectious
west texas to california, regions of mexico
inf after rainy seasons and dust storms
inf through inhalation of arthrospores
diffuse pneumonia and disseminated
dx by serology - immunodiffusion and complement fixation (IgG), seeing spherule, or culture
tx = ampho b for pneumonia, ampho + itraconazole for disseminated, LIFELONG fluconazole for meningitis
What are the key points about blasto?
mississippi and ohio river valleys, not texas
exposure to moist soil
culture or antigen testing in urine and blood
pneumonia, extra-pulm in HIV (meningitis, mass lesions)
ampho b for severe, itraconazole for maintenance
What are the key points about sporotrichosis?
inf from traumatic inoculation into skin
cutaneous manifestations, disseminated in AIDS (high mortality)
dx by culture, no antigen test
What are the key points about penicillium marneffei (penicilliosis)?
red pigment in culture southeast asia and southern china tb-like pulm syndrome, dissemination, umbilicated lesions in skin and mucous membranes no antigen test, dx by culture or biopsy maintenance therapy for life
What are the three main take home points?
candida in AIDS is usually mucosal
crypto is major cause of meningitis
disseminated dz is most common presentation of endemic mycoses
What is antifungal diagnosis in a nutshell?
antigen testing for crypto and histo
serology for cocci
What is antifungal therapy in a nuthsell?
ampho b for basically everything
fluconazole - the 3 C’s = crypto, cocci meningitis, candidiasis
itraconazole for histo, sporotrichosis, penicilliosis
