Infectious Disease 2 Flashcards
How would you confirm a Dx of C Diff colitis?
C diff produces exotoxins that cause mucosal inflammation/injury. A Dx of C diff can be confirmed with stool studies for C Diff toxin via PCR or enzyme immunoassay.
*Pt with neg (-) PCR and pos(+) sx may need sigmoidoscopy or colonoscopy with biopsy to document pseudomembranous colitis.
Rx = metro or PO Vanco
What Abx are most likely to precipitate C Diff colitis (4 are listed)?
fluoroquinolones, penicillins, cephalosporins, and clindamycini.
What’s the most common complication of influenza virus infection in a Pt with chronic Dz?
Pneumonia is the most common complication of influenza. Can be due to secondary bacterial infection or direct viral attack (influenza pneumonia). Pt with primary influenza pneumonia present with acute worsening of Sx, leukocytosis, hypoxia, and bilateral diffuse interstitial infiltrates on CXR which require supplemental O2 and hospitalization.
** Pseudomonas aeruginosa and S pneumo can cause secondary bacterial pneumonia, but this typically presents with high fever, significant leukocytosis and lobar (not reticular) infiltrates on CXR.
What is the standard treatment for toxoplasmosis infection?
Several weeks of sulfadiazine + pyrimethamine (plus leucovorin to prevent hematologic side effects).
Prophylaxis = TMP-SMX when CD4 < 100
What is the clinical manifestation/presentation of toxoplasmosis?
Headache, confusion, fever, and focal neurologic deficits/seizures. MRI shows ring enhancing lesions (with preference at basal ganglia).
Dx is supported by Tgondii IgG serology + MRI findings
If a young patient (19yo) presents to the ED with high fever, productive cough/hemoptysis, leukopenia, and multilobar cavitary infiltrates on CXR after having a recent URI, what would be the most likely Dx?
Community acquired MRSA. Can cause severe necrotizing pneumonia that is rapidly progressive and fatal. Occurs in young Pt as secondary infection after URI. Should start empiric Abx (vanco or linezolid)
What’s the treatment of choice for legionella?
Respiratory fluoroquinolone (levofloxacin) or newer macrolide.
What diagnostic findings would confirm a Dx of legionella?
Bilateral lung infiltrates, fever, confusion, and diarrhea following travel are pathognomonic.
Lung exam shows rales and CXR shows interstitial infiltrate. Hyponatremia is common. Sputum gram stain may show lots of neutrophils but no bacteria because it is an intracellular G(-) organism.
What organism is most likely responsible for community acquired pneumonia in HIV patients?
S pneumo. Probably due to ^ colonization and impaired immunity against encapsulated organisms. Typically happens when CD4 <200. AIDS patients should get pneumococcal vaccine to decrease risk of invasive S pneumo.
Sx of CAP = fever, pleuritic chest pain, SOB, dyspnea, and productive cough. Dx is often confirmed on CXR by finding a lobar, interstitial, or cavitary infiltrate.
What are the recommended vaccinations for HIV patients?
- Hep B (unless documented immunity)
- Annual influenza
- Revaccination for tetanus/diphtheria (Td) every 10 yr
- S pneumo 13 valent pneumococcal conjugate vaccine (PCV13) followed by 23 valent pneumococcal polysaccharide vaccine (PPSV23) 8 wks later»_space; 5 yrs later (and again at 65)
- Varicella vaccine for Pt born after 1979 and with CD4 > 200
What confirmatory test is used to Dx herpes encephalitis?
Dx is confirmed by detecting viral DNA by PCR in CSF.
Rx with early empiric acyclovir.
What Rx would you give for vibrio vulnificus?
IV ceftriaxone + doxycycline
** Vibrio = G(-) bacteria in marine environments. Can contaminate wounds or through oysters. Look out for Pt with liver disease (hemochromatosis or alcoholic cirrhosis) because these are at risk for nec fasc and septic shock. Pt with hemochromatosis are at ^ risk because free iron acts as growth catalyst.
What’s the preferred regimen for AIDS Pt with new Dx of PCP?
TMP-SMX + corticosteroids (if PaO2 < 70mmHg or A-a gradient > 35 mmHg on room air). ** The corticosteroids improve mortality by reducing inflammation from dying organisms.
PCP is likely in HIV Pt who have a nonproductive cough, exertional dyspnea, fever, severe hypoxia, and bilateral interstitial infiltrates.
TMP-SMX is the primary treatment for AIDS Pt with PCP. What alternative therapies exist?
Alternative Rx in mild-moderate Dz = dapsone + TMP, primaquine + clinda, atovaquone
Alternative Rx in moderate-severe Dz = primaquine + clinda, or IV Pentamidine (bad adverse effects though)
What is the Rx for entamoeba histolytica?
Metro + intraluminal Abx (paromomycin).
** Most Pt are asymptomatic but 10% of Pt can have clinical Sx of colitis or extraintestinal (liver, pleura, brain) disease. Can have liver abscess formation as ameba spreads from colonic mucosa to liver via hepatic portal vein.
