Lecture 7 - Infections in Immunocompromised Host Flashcards

1
Q

What causes predisposition to infection?

A

neutropenia
defects in the phagocytic defense
defects in cellular immunity
defects in humoral immunity

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2
Q

Incidence and severity of infection are inversely proportional to the _____

A

absolute neutrophil count (ANC)

risk of infection is significant at ANC <500

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3
Q

Phagocytic defenses help us protect against what types of pathogens?

A

gram negative rods: E. coli, psuedomonas, klebsiella

gram positive: staph, strep

fungi: candidi, asperguillus and mucor

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4
Q

Which pathogens do you really only see as opportunistic pathogens?

A

Bacteria:
listeria, mycobacteria, nocardia, legionella, salmonella

Fungi:
cryptococcus, histoplasma, coccidioides, pneumocystis

Viruses:
VZV, HSV, CMV

Helminths: stronglyoids stercoralis

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5
Q

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?

A

rapid initiation of empiric antimicrobial therapy = MANDATORY

if they’re not getting any better you should be thinking fungus

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6
Q

What are common infections in the neutropenic pt?

A

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

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7
Q

What are the principles of therapy for neutropenic pts?

A

initial: empiric
cover gram negative

recovery of neutrophil count is prognostic factor

if pt remains febrile despite antibacterial coverage – consider antifungal therapy

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8
Q

In pts with HIV, pneumocystis jiroveci is an opportunistic infection when the CD4 count is what?

A

<200

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9
Q

What infections are we seeing in HIV pts with a CD4 < 100?

A
cryptococcal infections 
MAI 
CMV
toxoplasma 
cryptosporidium
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10
Q

CMV treatment

A

gancyclovir

major SE of gancyclovir is pancytopenia or neutropenia

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11
Q

Which species is most commonly involved in oropharyngeal infections of HIV pts?

A

candidia albicans

this infection can occur at high CD4 counts

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12
Q

How can you tell the difference between thrush and oral hairy leukoplakia?

A

oral hairy leukoplakia you can not scrap off

dx of thrush is via KOH prep

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13
Q

Besides thrust and oral hairy leukoplakia, what other oral ulcers are seen in HIV pts?

A

HSV
CMV: large, shallow ulcers
Aphthous stomatitis: ulcerations with exudate at the base

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14
Q

How are oral ulcers dx in pts with HIV?

A

cultures, biopsy
KOH prep: thrush
EM: CMV

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15
Q

Which cutaneous infections are seen with HIV pts?

A

VZV, HSV, Bacillary angiomatosis, molluscum contagiosum

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16
Q

How is genital HSV dx in an HIV pt?

A

PCR

same way to dx VZV

both of these can recur regardless of the CD4 count

17
Q

Bacillary angiomatosis

A

a skin infection see in HIV pts

bartonella henselae

18
Q

Mollusum contagiosum

A

a skin infection seen in HIV pts

poxvirus
small flesh-colored umbilicated lesions

19
Q

CMV retinitis

A

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

20
Q

Which vaccine is given to HIV pts to decrease risk of recurrent PNAs?

A

Prevnar

21
Q

Which pulmonary infections are commonly seen in HIV pts?

A

bacterial (strep, staph, h. flu)
pneumocystis jiroveci (PJP)
fungal (aspergillus, histpolasma, crypto)
mycobacterial (MAC - MTB and MIA)

22
Q

PJP clinical manifestations

A

insidious onset of fever, sweats, fatigue, non-productive cough
dyspnea is initially exertional, but progresses with impairment of gas exchange

23
Q

How is PJP dx?

A

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

24
Q

What is the most common non-tuberculous pulmonary mycobacterial infection seen in HIV pts?

A

m. kansasii

25
Q

CMV clinical manifestation

A

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

26
Q

Crypotosporidium

A

usually causes a persistent diarrheal disease
can also cause acalculous cholescytitis

dx: stool PCR

27
Q

What CNS infections are seen with HIV pts?

A

cryptococcus
toxoplasma
CMV
PML, JC virus

28
Q

How is Cryptococcal Meningitis dx?

A

CSF analysis with INDIA INK STAIN

29
Q

Toxoplasmosis

A

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

30
Q

India ink stain

A

used to dx cryptococcal meningitis

31
Q

MAC prophylaxis

A

Begin prophylaxis at CD4 count <50

Prophylaxis with azithromycin 1200mg weekly

32
Q

PCP prophylaxis

A

Being prophylaxis at CD4 count <200
Bactrim DS (trimethoprim-sulfamethoxazole)
Also protects against toxoplasma