Lecture 7 - Infections in Immunocompromised Host Flashcards
What causes predisposition to infection?
neutropenia
defects in the phagocytic defense
defects in cellular immunity
defects in humoral immunity
Incidence and severity of infection are inversely proportional to the _____
absolute neutrophil count (ANC)
risk of infection is significant at ANC <500
Phagocytic defenses help us protect against what types of pathogens?
gram negative rods: E. coli, psuedomonas, klebsiella
gram positive: staph, strep
fungi: candidi, asperguillus and mucor
Which pathogens do you really only see as opportunistic pathogens?
Bacteria:
listeria, mycobacteria, nocardia, legionella, salmonella
Fungi:
cryptococcus, histoplasma, coccidioides, pneumocystis
Viruses:
VZV, HSV, CMV
Helminths: stronglyoids stercoralis
Normally for FUO we do not treat with ABX until we know what is going on, however if they have neutropenia what do we do?
rapid initiation of empiric antimicrobial therapy = MANDATORY
if they’re not getting any better you should be thinking fungus
What are common infections in the neutropenic pt?
oropharygneal infections (HSV, candida, bacterial infections)
pulmonary infections (CMV in the setting of bone marrow transplantation)
skin and soft tissue infections (pts often have long term IV devices, offending organism typically skin flora
What are the principles of therapy for neutropenic pts?
initial: empiric
cover gram negative
recovery of neutrophil count is prognostic factor
if pt remains febrile despite antibacterial coverage – consider antifungal therapy
In pts with HIV, pneumocystis jiroveci is an opportunistic infection when the CD4 count is what?
<200
What infections are we seeing in HIV pts with a CD4 < 100?
cryptococcal infections MAI CMV toxoplasma cryptosporidium
CMV treatment
gancyclovir
major SE of gancyclovir is pancytopenia or neutropenia
Which species is most commonly involved in oropharyngeal infections of HIV pts?
candidia albicans
this infection can occur at high CD4 counts
How can you tell the difference between thrush and oral hairy leukoplakia?
oral hairy leukoplakia you can not scrap off
dx of thrush is via KOH prep
Besides thrust and oral hairy leukoplakia, what other oral ulcers are seen in HIV pts?
HSV
CMV: large, shallow ulcers
Aphthous stomatitis: ulcerations with exudate at the base
How are oral ulcers dx in pts with HIV?
cultures, biopsy
KOH prep: thrush
EM: CMV
Which cutaneous infections are seen with HIV pts?
VZV, HSV, Bacillary angiomatosis, molluscum contagiosum
How is genital HSV dx in an HIV pt?
PCR
same way to dx VZV
both of these can recur regardless of the CD4 count
Bacillary angiomatosis
a skin infection see in HIV pts
bartonella henselae
Mollusum contagiosum
a skin infection seen in HIV pts
poxvirus
small flesh-colored umbilicated lesions
CMV retinitis
ocular infection seen in pts with HIV
sxs include progressive visual loss, blurring and “floaters”
fundoscopic exam reveals coalescing white exudates with surrounding hemorrhage and edema
without treatment will progress to retinal detachment and visual loss
Which vaccine is given to HIV pts to decrease risk of recurrent PNAs?
Prevnar
Which pulmonary infections are commonly seen in HIV pts?
bacterial (strep, staph, h. flu)
pneumocystis jiroveci (PJP)
fungal (aspergillus, histpolasma, crypto)
mycobacterial (MAC - MTB and MIA)
PJP clinical manifestations
insidious onset of fever, sweats, fatigue, non-productive cough
dyspnea is initially exertional, but progresses with impairment of gas exchange
How is PJP dx?
blood gases reveal reduced oxygen levels and commonly low PCO2 levels
CXR most commonly reveal diffuse interstitial infiltrates (80%), but lobar, nodular, cavitary, asymmetric patterns can also occur
sputum, bronchoalveloar lavage or biopsy specimens are sent for staining
What is the most common non-tuberculous pulmonary mycobacterial infection seen in HIV pts?
m. kansasii
CMV clinical manifestation
can affect the entire GI system: esophagitis, gastritis, colitis
pts present with odynophagia, diarrhea, proctitis, fever, abdominal pain
can cause acalculous cholescystitis
dx: PCR, endoscopy or colonoscopy with biopsy and EM
Crypotosporidium
usually causes a persistent diarrheal disease
can also cause acalculous cholescytitis
dx: stool PCR
What CNS infections are seen with HIV pts?
cryptococcus
toxoplasma
CMV
PML, JC virus
How is Cryptococcal Meningitis dx?
CSF analysis with INDIA INK STAIN
Toxoplasmosis
HA, confusion, behavior/mood changes
can also cause ocular disease
ring enhancing lesion or lesions on CT or MRI
in HIV it is reactivation – IgG will be positive for all, dx by CSF PCR
India ink stain
used to dx cryptococcal meningitis
MAC prophylaxis
Begin prophylaxis at CD4 count <50
Prophylaxis with azithromycin 1200mg weekly
PCP prophylaxis
Being prophylaxis at CD4 count <200
Bactrim DS (trimethoprim-sulfamethoxazole)
Also protects against toxoplasma
