Infectious Disease Flashcards Preview

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Flashcards in Infectious Disease Deck (18):
1

Malignant otitis externa

Symptoms: ear discharge and severe ear pain that radiates to the TMJ; also granulation tissue in the ear canal

Risk factors: diabetes mellitus and other immunosuppressing conditions

- not responsive to topical antibiotics

2

HIV post-exposure prophylaxis

- Initiate therapy within first few hours and continue to treat for 28 days

3 drug regimen: 2 NRTIs (tenofovir and emtracitabine)
integrase strand transfer inhibitor (raltegravir), protease inhibitor, or NNRTI

- Risk of seroconversion is

3

Acute pyelonephritis treatment

Uncomplicated: Mild to moderate - TMX or fluoroquinolones (cipro)
Severe - IV ceftriaxone, TMX, or fluoroquinolones (cipro or levo)

Complicated - indwelling catheter, urinary obstruction or retention, recent urologic procedure or hospital-aquired infection, renal impairment with azotemia, immunosuppression, and diabetes

IV antibiotics and hospitalization
Mild to moderate - ceftriaxone, cefepime, fluoroquinolones (levo and cipro)
Severe - ampicillin-sulbactam, ticarcillin-clavulanate, piperacillin-tazobactam, meropenem, imipenem, aztreonam (+or- gentamicin)

- Diabetic pts are started on IV Abs and then switched to oral after 48-72 hours. Oral antibiotics are continued for 10 - 14 days.

4

Histoplasmosis

- Present in soil, bird and bat droppings; no human to human spread
Immunocompetent: asymptomatic or mild pulmonary disease
Immunocompromised: pancytopenia, hepatosplenomegaly, and adenopathy
- Reticulonodular or cavitary pneumonia, mucocutaneous ulcers

Diagnosis: pancytopenia, elevated LDH and ferritin, elevated liver enzymes, positive urine or serum antigen, blood culture, or microscopy

Treatment: Immunocompetent - no treatment or oral itraconazle
Immunocompromised, severe infection, or disseminated disease - amphotericin B w/ switch to itraconazole after initial response
-Seen in AIDS patients with CD4 counts

5

Crytptococcal meningoencephalitis

- seen in HIV pts with CD4or= 1 yr)

- Wait 2-8 wks after induction therapy before starting antiretrovirals due to risk of immune reconstitution syndrome.
-May require serial lumbar punctures to reduce pressures.

6

Invasive aspergillosis

- Occurs in immunocompromised pts

Symptoms: fever, cough, dyspnea, hemoptysis

CXR: cavitary lesion
CT scan: pulmonary nodules wi/ halo sign or air crescent

7

Bacillary angiomatosis

- Caused by Bartonella hensalae and Bartonella quintana (Gram negative bacillus)
- Common in immunosuppressed pts

Symptoms: exophytic purple skin masses, hepatomegaly and intrahepatic lesions, fever, weight loss, abdominal pain

Treatment: oral erythromycin

- High risk of hemorrhage during liver biopsy.

8

Isoniazid for TB

- mild, subclinical liver injury is common with severe hepatitis only affecting a small number of people.

- Continue treatment in healthy pts with mild liver injury and monitor closely.
- With severe hepatitis, switch to second-line therapy.

9

Treatment of Lyme disease in pregnancy

Oral amoxicillin

10

Acute HIV infection

Symptoms: fever, lymphadenopathy, sore throat, arthralgias, macular rash, GI symptoms

- HIV Ab may be negative (not yet seroconverted)

11

Prophylaxis criteria for Lyme disease

Must meet all 5:
1. Attached tick is an adult or nymphal Ixodes scapularis
2. tick attached for >or= to 36 hours or its engorged
3. Prophylaxis started within 72 hrs of removal
4. Local Borrelia burgdorferi infection rate >20%
5. no contraindications to doxycycline

12

Rubella

Congenital: sensorineural hearing loss, intellectual disability, cardiac anomalies, cataracts, glaucoma

Children: low-grade fever, conjunctivitis, coryza, cervical lymphadenopathy, Forschheimer spots (petechaie on the soft palate), cephalocaudal spread of blanching, erythematous maculopapular rash (spares the soles and palms)

Adults and adolescents: same as children + arthralgias/arthritis

Diagnosis: PCR, acute and convalescent serology for anti-rubella IgM and IgG

Prevention: Live attenuated vaccine

Treatment: supportive

Complications: postinfectious encephalitis

13

Measels

- Higher fever (>104), more gradual cranial-caudal spread of the rash, arthritis is not present

14

Paroxysmal nocturnal hemoglobinuria

Symptoms: fatigue, cytopenia, and venous thrombosis (abdominal, cerebral)

Diagnosis: pancytopenia, elevated LDH and decreased haptoglobin, indirect hyperbilirubinemia, hemoglobinuria, absence of CD55 and CD59 (lack of glycosylphosphatidylinositol which prevents complement inhibitory proteins on the cell surface from working).
- Absence allows the membrane attack complex to form.

Treatment: iron and folate supplementation and eculizumab
(inhibits complement activation)

- Both intravascular and extravascular hemolysis.
- Symptoms in the 4th decade.

15

Tuberculosis

Infection: accumulation of neutrophils, macrophages and bacilli in the lower lung forms a tubercle w/ associated lympadenopathy forming a Gohn complex -----> cell-mediated immune response w/ latent TB

Reactivation: cough, weight loss, fever, night sweats
CXR - upper lobe infiltrates w/ cavities

16

Chronic hepatitis B

4 phases:

1. Immune tolerance
- High levels of HBV replication
- HBsAg and HBeAg (high viral replication) positive with elevated HBV DNA
- Normal ALT, minimal inflammation on liver biopsy
- Can last for 10-30 yrs

2. Immune clearance
- HBeAg initially positive w/ eventual clearance
- HbsAg positive
- Variable elevation of ALT due to immune-mediated lysis of infected hepatocytes
- Active liver inflammation w/ or w/o fibrosis on liver biopsy
- Can have increased HBV DNA and IgM ant-HBc titer

3. Inactive carrier state
- HBeAg negative, positive anti-HBe, HBsAg remains positive
- HBV DNA very low or undetectable
- variable signs of liver inflammation
- Need at least 3 normal ALT levels and 2-3 normal HBV DNA levels over a 12 month period to confirm inactive carrier state.

4. HBeAg-negative chronic hepatitis (reactivation)
- HBV DNA moderately elevated
- ALT elevated with chronic inflammation on liver biopsy
- HBeAg remains negative

17

Splenic abscess

Risk factors:
- Infection w/ hematogenous spread (infective endocarditis)
- Hemoglobinopathy
- Immunosuppression
- IV drug use
- Trauma

Presentation:
- Classic triad: fever, leukocytosis, LUQ abdominal pain
- Left-sided pleuritic chest pain w/ left-sided pleural effusion
- Splenomegaly
- Most commonly due to Staph, Strep, and Salmonella
- Diagnosed on abdominal CT

Treatment: broad-spectrum antibiotics and splenectomy

18

Benefit of digoxin in CHF

- Decreases hospitalization