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STEP2 > Infectious Disease > Flashcards

Infectious Disease Flashcards

1
Q

What drugs are used to treat MRSA?

A
  • vancomycin, linezolid, daptomycin, and ceftaroline are IV drugs most often used
  • bactrim, doxycycline, clindamycin, and linezolid can be used as PO formulations for minor skin infections
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2
Q

Describe the etiology, presentation, management, and treatment of bacterial meningitis.

A
  • most common etiologies in order are Strep pneumo, GBS, Hib, N. meningitidis, and Listeria
  • presents with fever, headache, neck stiffness, and photophobia which develop over the course of hours
  • LP is the best initial and most accurate test
  • must perform a CT before LP if patient has papilledema, seizures, focal neurologic deficits, or confusion interfering with the neurologic exam; in these cases the best first step is to start antibiotics
  • empiric treatment should be started if an LP is contraindicated or shows thousands of neutrophils; use vancomycin and ceftriaxone; add ampicillin if patient has risk factors for Listeria (elderly, young, pregnant, or immunocompromised)
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3
Q

Describe the appropriate management of bacterial meningitis.

A
  1. LP is the best initial and most accurate step
    - CT must be performed first if there are signs of a mass lesion: seizures, confusion, papilledema, focal deficits
    - Antibiotics are the best first step if this is the case, before going to CT
  2. If CT is clear, perform the LP and begin treatment if there is a predominately neutrophilic infiltrate
  3. Empiric treatment is with vancomycin and ceftriaxone with ampicillin added if patients have risk factors like being elderly, young, immunocompromised, or pregnant
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4
Q

What is the appropriate treatment for N. meningitidis meningitis?

A
  • place the patient in respiratory isolate
  • treat patient with ceftriaxone
  • treat close contacts, those with respiratory fluid contact and not just routine school and work contacts, with rifampin
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5
Q

What should the first step be in patients with suspected meningitis?

A
  • best first step is an LP
  • if this is contraindicated, start antibiotics
  • CT comes after one of the above
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6
Q

What is the most common neurologic complication of untreated meningitis?

A

CN VIII deficits like hearing loss

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7
Q

Describe the most common etiology, presentation, diagnosis, and treatment of encephalitis.

A
  • most often due to HSV infection
  • present with acute onset of fever and confusion
  • the first step in workup is a head CT due to the presence of confusion; this will likely show a temporal lobe lesion
  • the most accurate test for diagnosis will then be an LP with HSV PCR
  • treat with acyclovir; use foscarnet for resistant herpes
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8
Q

Describe the presentation and management of influenza.

A
  • presents with sudden onset arthralgias, myalgia, cough, fever, sore throat, headache, n/v
  • perform a rapid flu test only if symptoms started in the last 48 hours; otherwise, results don’t affect managment
  • if disease onset was in the last 48 hours, treat with the neuraminidase inhibitors oseltamivir or zanamivir to shorten duration; otherwise, use supportive care
  • also use neuraminidase inhibitors if patients are sick enough to be hospitalized
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9
Q

What is the best initial and what is the most accurate test for infectious diarrhea?

A
  • best initial is a test for fecal blood and lactoferrin or leukocytes
  • the most accurate is stool culture
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10
Q

What is the most common cause of diarrhea in patients with CD4 count less than 100?

A

cryptosporidiosis

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11
Q

How should infectious diarrhea be treated?

A
  • use PO fluid replacement for mild disease
  • if patients have severe disease including hypotension, fever, bloody diarrhea, or metabolic acidosis, use fluid replacement and oral antibiotics
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12
Q

How are hepatitis A, B, C, and E transmitted?

A
  • HepA by the fecal-oral route
  • HepB primarily by sexual exposure
  • HepC primarily via the parenteral route
  • HepE by the fecal-oral route
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13
Q

What is the best predictor of mortality in those with acute hepatitis?

A

an elevated PT suggests a greater risk of fulminant hepatic failure and death

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14
Q

What drug is commonly known to reactive disease in those with chronic hepatitis B?

A

rituximab, since immunity is largely humoral

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15
Q

What is the window period for hepatitis B?

A
  • this is the period after anti-HBs IgM disappears but before anti-HBs IgG appears
  • patients will be negative for all markers of hepatitis B
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16
Q

How do we use HBsAg, HBeAg, and HepB PCR clinically?

A
  • HBsAg is the first marker to become abnormal after infection and its disappearance signifies that patients are no longer at risk of transmitting the infection
  • HBeAg is a qualitative marker for the presence of active viral replication and the need for treatment
  • HepB DNA, established through PCR, is a qualitative marker for the presence of active viral replication and the need for treatment
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17
Q

Which form of acute hepatitis is treated with antiviral therapy? Why?

A

hepatitis C is the only one for which treatment in the acute phase affects the likelihood of a chronic infection developing

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18
Q

What is the best initial diagnostic test for acute hepatitis?

A

an assay for IgM antibody against the hepatitis viruses

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19
Q

How do we monitor the response to treatment in those with chronic hepatitis B or C?

A

PCR levels are the first thing to change and the best correlate of response to treatment

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20
Q

Describe the transmission, presentation, diagnosis, and management of hepatitis B.

A
  • transmission is primarily through sexual contact
  • presents in the acute phase with fever, fatigue, jaundice, hepatosplenomegaly, GI upset, and RUQ pain
  • the best initial test for diagnosis is HBsAg as this is the first indicator to be positive
  • treatment doesn’t help shorten the acute phase or prevent the chronic phase so this isn’t indicated initially
  • treat chronic infection with antivirals to prevent fibrosis and cirrhosis
  • use HepB PCR as a qualitative measure for viral replication and the response to treatment
  • patients are infectious until HBsAg is no longer detected
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21
Q

Describe the transmission, presentation, diagnosis, and management of hepatitis C.

A
  • transmission is parenteral
  • acute presentation is rare, so we screen everyone born between 1945 and 1965
  • the best initial test for diagnosis is anti-Hep C IgM and this should be followed with a HCV DNA level if positive
  • treatment reduces the risk of and cures chronic disease so patients with positive HCV DNA should all start treatment
  • use sofosbuvir and either velpatasvir or ledipasvir (for genotype 1)
  • monitor HCV DNA as a measure of treatment response
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22
Q

What are the most common adverse effects of interferon therapy?

A
  • arthralgias and myalgias
  • anemia, leukopenia, and thrombocytopenia
  • depression
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23
Q

What aspect of hepatitis C is used to predict the response to therapy? What is used to monitor the response to therapy?

A
  • the genotype predicts the response and determines the appropriate treatment
  • HCV DNA is used to monitor the response
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24
Q

Describe the presentation, diagnosis, and treatment of urethritis.

A
  • as with cystitis, it presents with dysuria and urinary frequency; however, urethral discharge is also present
  • diagnosis is with NAAT for gonorrhea and chlamydia
  • treat with ceftriaxone and azithromycin for gonorrhea and just azithromycin for chlamydia
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25
Q

Describe the etiology, presentation, and treatment of epididymitis.

A
  • in males less than 35, it tends to be caused by g/c; however, gram-negative rods like E. coli tend to be the agent responsible in older males
  • presents with scrotal pain and point tenderness superior and lateral to the testicle which develops over a few days
  • treat younger males with ceftriaxone plus azithromycin; treat older males with bactrim or a quinolone
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26
Q

Describe the presentation, diagnosis, and treatment of pelvic inflammatory disease.

A
  • presents with lower abdominal pain and tenderness, cervical motion tenderness, fever, and leukocytosis
  • the best first test is B-hCG to rule out pregnancy; NAAT for G/C is the best diagnostic test; laparoscopy is the most accurate test but is rarely done
  • treat outpatient with ceftriaxone and doxycycline; treat inpatient with cefoxitin or cefotetan plus doxycycline; treat penicillin allergy with gentamicin plus clindamycin
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27
Q

What is the defining feature for each of the following ulcerative genital diseases:

  • syphilis
  • Haemophilus ducreyi
  • lymphogranuloma venereum
  • Herpes simplex
A
  • syphilis: single painless ulcer
  • Haemophilus ducreyi: single painful ulcer
  • lymphogranuloma venereum: tender, suppurative lymphadenopathy
  • Herpes simplex: multiple painful ulcers
28
Q

Describe the presentation, diagnosis, and treatment of primary syphilis.

A
  • presents with a single painless ulcer often accompanied by painless lymphadenopathy
  • RPR and VDRL are sensitive tests; dark field and FTA are specific tests
  • treat with single dose of penicillin; doxycycline if allergic
29
Q

Describe the presentation, diagnosis, and treatment of Haemophilus ducreyi.

A
  • presents with a single painful ulcer on a friable base
  • culture is the best diagnostic test
  • treat with azithromycin
30
Q

Describe the presentation, diagnosis, and treatment of lymphogranuloma venereum.

A
  • presents with painful, suppurative lymphadenopathy
  • diagnosis is with NAAT or complement fixation titers
  • treat with doxycycline
31
Q

Describe the presentation, diagnosis, and treatment of genital herpes.

A
  • presents with multiple vesicles that evolve into painful ulcers
  • treatment is initiated based on presentation; however, PCR is the most accurate test and viral cultures help determine sensitivities
  • treat with oral acyclovir; foscarnet if resistant
32
Q

What is the treatment for each of the following:

  • syphilis
  • Haemophilus ducreyi
  • lymphogranuloma venereum
  • Herpes simplex
A
  • syphilis: single dose penicillin; doxycycline if allergic
  • Haemophilus ducreyi: single dose azithromycin
  • lymphogranuloma venereum: doxycycline
  • Herpes simplex: oral acyclovir
33
Q

Describe the manifestations of tertiary syphilis.

A
  • neurosyphilis: tabes dorsalis, meningovascular inflammation with stroke, and memory and personality changes
  • aortitis: aortic regurgitation and aortic aneurysm
  • gummas: skin and bone lesions
34
Q

What is the most sensitive test for neurosyphilis?

A

FTA of the CSF

35
Q

Describe the presentation and treatment of a Jarisch-Herxheimer reaction.

A
  • presents as fever and worsening symptoms after initiation of syphilis treatment
  • treat with aspirin and antipyretics as it is self-limited
36
Q

When is desensitization and treatment with penicillin the answer?

A

for neurosyphilis and syphilis in pregnant women

37
Q

Describe the treatment of primary, secondary, and tertiary syphilis.

A
  • primary and early secondary: single dose of penicillin; doxycycline if allergic
  • late secondary: penicillin weekly for three weeks
  • tertiary: IV penicillin
  • desensitization and treatment with penicillin is the right answer for pregnant women and those with neurosyphilis
38
Q

How are condylomata acuminata treated?

A
  • treated based on presentation and requires no diagnostic testing
  • use physical agents such as cryotherapy, surgery, trichloroacetic acid, or imiquimod
39
Q

Describe the presentation and treatment of pediculosis.

A
  • presents as itching with visible “crabs” on hair-bearing areas
  • treat with permethrin
40
Q

How are scabies diagnosed and treated?

A
  • diagnosis is based of scrapings and magnification

- treat with permethrin; use ivermectin for widespread disease that is crusted or hyperkeratotic

41
Q

What is the best initial and what is the most accurate test for UTI?

A
  • best initial is urinalysis

- most accurate is urine culture

42
Q

How is cystitis treated?

A
  • treatment is started based on clinical presentation and the presence of WBCs in the urine
  • options for treatment include nitrofurantoin, fosfomycin, bactrim, and cefixime
  • treat uncomplicated cases for 3 days and complicated for 7 days
43
Q

When should urine culture or imaging be done for those with cystitis?

A

only done for frequent episodes of cystitis or failure to respond to therapy

44
Q

Describe the etiology, presentation, management, and treatment of pyelonephritis.

A
  • most commonly due to E. coli, Enterococcus faecalis, or Klebsiella
  • presents with CVA tenderness, high fever, and symptoms of cystitis
  • diagnosis is made based on urinalysis and clinical presentation
  • ciprofloxacin is first-line for treatment; other options include ceftriaxone or ampicillin plus gentamicin
  • get a CT or US if fever fails to resolve after 5-7 days looking for a perinephric abscess, which requires drainage and culture
45
Q

What is pentosan?

A

an analgesic that treats bladder-specific pain

46
Q

When should you suspect perinephric abscess and how is it managed?

A
  • should be suspected in those with pyelonephritis that fails to respond to therapy or that has a fever persisting after 5-7 days of antibiotics
  • get an US or CT to diagnose then drain and culture the fluid
47
Q

Describe the etiology, presentation, diagnosis, and treatment of prostatitis.

A
  • usually bacterial: Chlamydia trachomatis and Neisseria gonorrhoeae in younger males; E. coli and Pseudomonas are more common in older adults
  • presents with dysuria, fever, and chills, urgency, low back or perineal pain, and a tender prostate
  • diagnosis is with UA and urine culture following prostate massage; chronic prostatitis is more likely to be culture negative
  • treat as you would with pyelonephritis; ciprofloxacin or bactrim for 2-6 weeks depending on chronicity of the infection
48
Q

What are the most common etiologic agents for endocarditis of the following kinds:

  • most common overall
  • most common cause of subacute endocarditis
  • most common in IV drug users
  • most common in those with a prosthetic valve
  • most common in those with underlying colorectal carcinoma
  • most common in those with negative blood cultures
A
  • overall: Strep viridans
  • subacute: Strep viridans
  • IV drug users: Staph aureus
  • prosthetic valve: Staph epidermidis
  • colorectal carcinoma: Strep bovis and Clostridium septicum
  • negative blood cultures: Coxiella burnetii, Bartonella spp., and HACEK organisms (Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella)
49
Q

Describe the etiology, risk factors, presentation, and diagnosis of endocarditis.

A
  • the most common overall cause is Strep viridans; Staph aureus is common in IV drug users and Staph epidermidis in those with a prosthetic valve
  • Coxiella, Bartonella, and HACEK organisms are the most common causes of culture negative endocarditis
  • risk is directly proportional to the degree of valvular damage so prosthetic valves have the greatest risk, stenotic and regurgitant valves have high risk, and normal valves are usually only affected by severe bacteremia as with IV drug use
  • presents with fever, a new or changing murmur, and evidence of septic emboli
  • diagnosis should involve blood cultures with TTE; use TEE if TTE is negative
50
Q

How is endocarditis treated?

A
  1. the best initial treatment is vancomycin and gentamicin
    - for Strep viridans switch to ceftriaxone
    - for MSSA use oxacillin, nafcillin, or cefazolin
    - for MRSA or Staph epidermidis use vancomycin or daptomycin
    - for enterococci use ampicillin and gentamicin
    - for culture negative organisms use ceftriaxone
    - for fungal use amphotericin
  2. add an amino glycoside and extend the duration of treatment if any of the above is shown to be resistant
  3. surgery is indicated for CHF secondary to valve or chordae tendineae rupture, prosthetic valves, fungal endocarditis, abscesses, AV block, and recurrent emboli while on antibiotics
51
Q

What antibiotic is used for each of the following causes of endocarditis:

  • Strep viridans
  • MSSA
  • MRSA
  • Staph epidermidis
  • Enterococci
  • HACEK
  • fungal
A
  • Strep viridans: ceftriaxone
  • MSSA: nafcillin, oxacillin, or cefazolin
  • MRSA: vancomycin or daptomycin
  • Staph epidermidis: vancomycin or daptomycin (plus rifampin if involving a prosthetic valve)
  • Enterococci: ampicillin and gentamicin
  • HACEK: ceftriaxone
  • fungal: amphotericin and surgery
52
Q

Under what circumstances is endocarditis prophylaxis indicated? What is used?

A

amoxicillin is used if two criteria are met:

  1. a significant cardiac defect must be present, including a prosthetic valve, previous endocarditis, uncorrected cyanotic heart disease, or valvular disease of a cardiac transplant
  2. risk of bacteremia defined by dental work with blood or respiratory tract surgery that produces bacteremia
53
Q

Describe the presentation, diagnosis, and treatment of lyme disease.

A
  • presents early on with erythema migrans, fever, and flu-like symptoms
  • oligoarthritis, Bell palsy, and AV block are the most common symptoms of secondary and tertiary disease
  • erythema migrans is sufficient to make the diagnosis but in all other circumstances, serology must be performed before initiating treatment
  • use doxycycline (if over eight years old) or amoxicillin for rash, arthritis, or Bell palsy
  • use IV ceftriaxone for cardiac and neurologic manifestations other than Bell palsy
54
Q

Which modalities have the highest risk of transmitting HIV from an individual with uncontrolled disease?

A
  • vertical transmission from mother to child has the highest risk
  • receptive anal sex and needle stick injury follow
55
Q

Describe the diagnosis of HIV. What role does viral load testing play? What role does viral resistant testing play?

A
  • the best initial test is the HIV 1/2 antibody, P24 antigen ELISA test
  • PCR (viral load testing) is useful in infants because maternal HIV antibodies make the ELISA unreliable
  • confirm results with a western blot
  • PCR is later useful as a measure of the response to therapy and for detection of treatment failure
  • viral resistant testing is performed at the time of initial diagnosis before starting treatment in most populations; it is also performed if there is evidence of treatment failure
56
Q

Describe the treatment of HIV.

A
  • in non-pregnant patients, treatment shouldn’t begin until viral resistance testing is performed; don’t wait for these results in pregnant patients
  • first-line therapy generally includes an integrase inhibitor and two NRTIs
  • use bactrim for prophylaxis if CD4 < 200 and add azithromycin for prophylaxis if CD4 < 100
57
Q

What adverse effect is associated with the following HIV medications:

  • zidovudine
  • stavudine
  • didanosine
  • abacavir
  • efavirenz
  • protease inhibitors
  • indinavir
  • tenofovir disoproxil
  • tenofovir alafenamide
A
  • zidovudine: anemia
  • stavudine: peripheral neuropathy and pancreatitis
  • didanosine: peripheral neuropathy and pancreatitis
  • abacavir: hypersensitivity or SJS reaction in those with HLA-B5701
  • efavirenz: vivid dreams or hallucinations
  • protease inhibitors: hyperlipidemia and hyperglycemia
  • indinavir: nephrolithiasis
  • tenofovir disoproxil: renal insufficiency, bone demineralization
  • tenofovir alafenamide: fewer side effects than disoproxil
58
Q

What are the indications for HIV PEP? What is the treatment?

A
  • indications include needle-stick injury, sexual exposure, or bite from a known HIV-infected individual
  • there are no indications for individuals with unknown HIV status
  • use 4 weeks of combination therapy
59
Q

How should HIV be managed in pregnancy?

A
  • continue current regimen of treatment if already on medications at the time of pregnancy
  • otherwise initiate treatment immediately without waiting for viral resistance testing
  • vaginal delivery is preferred if women have a viral load of less than 1000 copies; otherwise, a c-section is indicated
  • all babies should receive zidovudine intrapartum and for six weeks afterward to prevent transmission
60
Q

What regimen is used for HIV PrEP? What is a side effect of discontinuing PrEP?

A
  • use emtricitabine-tenofovir before the exposure and for at least one month after the last exposure
  • discontinuation may lead to reactivation of hepatitis B in those who are HBsAg positive
61
Q

What prophylactic care should those with HIV receive?

A
  • when CD4 count is less than 200, use bactrim for PCP prophylaxis
  • when CD4 count is less than 100, add clarithromycin or azithromycin for MAC prophylaxis
  • perform annual TB testing with PPD and use isoniazid plus pyridoxine for latent TB
  • patients should continue to receive yearly influenza vaccines and a pneumococcal vaccine every 5 years
62
Q

Describe the presentation of PJP, CMV, and MAC infection in those with AIDS.

A
  • PJP occurs in patients with CD4 < 200 not on bactrim prophylaxis and presents as fever, nonproductive cough, shortness of breath, and diffuse interstitial infiltrates on chest x-ray
  • CMV occurs with CD4 < 50 and presents with unilateral retinitis that may become bilateral, esophagitis, colitis, and pulmonary symptoms
  • MAC occurs with CD4 < 50 not on azithromycin prophylaxis and presents as wasting syndrome, lymphadenopathy, and anemia
63
Q

Describe the risk factors, presentation, diagnosis, and treatment of mucormycosis.

A
  • it occurs exclusively in immunocompromised patients, especially those with DKA, and deferoxamine increases the risk
  • presents with involvement of the nasal canals and eyes
  • diagnosis is with biopsy
  • treat with amphotericin
64
Q

Describe the presentation, diagnosis, and treatment of invasive aspergillosis.

A
  • presents with rapidly progressive pulmonary dysfunction and diffuse lung infiltrates in immunocompromised patients
  • sputum testing for galactomannan, B-D-glucan, and PCR are non-invasive and very specific if two of the three are positive but lack sensitivity so a biopsy is often needed
  • treat with voriconazole (amphotericin is inferior)
65
Q

What is used for malaria treatment and prophylaxis?

A

treatment of infection:
- plasmodium falciparum: mefloquine or atovaquone
- non-falciparum: chloroquine or primaquine
- severe: artemisinins like artemetther or artesunate
prophylaxis:
- mefloquine for the general population
- atovaquone for those with a history of psych illness

66
Q

What is unique about each of the following:

  • Chikunguya
  • Dengue
  • Zika
A
  • Chikunguya: joint pain
  • Dengue: bone pain, thrombocytopenia leading to petechiae/GI bleeding, leukocytosis, and elevated LFTs
  • Zika: microcephaly and Guillain-Barre
67
Q

Describe the transmission and presentation of Ebola.

A
  • transmitted only by direct contact with bodily fluids from a symptomatic individual
  • presents with a nonspecific viral illness followed by severe GI distress, low WBC count, thrombocytopenia, and elevated LFTs
  • eventually this progresses to encephalitis, hypovolemic shock, and death

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