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Internal Medicine > JH IM Board Review - Infectious Disease II > Flashcards

JH IM Board Review - Infectious Disease II Flashcards

1
Q

Influenza - Basic info - 2 major subtypes:

A

Influenza A and B.

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2
Q

Influenza - Clinical presentation - Seasonal influenza outbreaks typically occur in an epidemic pattern, peaking …?

A

At 2-3 weeks after introduction and completed after 5-6 weeks in any given community.

==> Seasonal peaks usually occur in winter, but may occur from early fall to late spring.

==> Influenza is UNCOMMON in the summertime.

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3
Q

Influenza - Clinical presentation - Symptoms often begin …?

A

Aburptly with fever, rigors, malaise, headache, myalgia, and arthralgia.

==> Fever, rigors and myalgia peak at 3 days, AFTER which resp. symptoms (cough) and nasal congestion predominate.

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4
Q

Influenza - Major complication is …?

A

Post-influenza pneumonia.

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5
Q

Influenza - Postinfluenza pneumonia:

A
  1. Viral pneumonia from influenz occurs early in course of disease and may be severe.
  2. Postinfectious bacterial pneumonia often follows a period of recovery from influenza and is most often caused by:

==> S.pneumo, S.aureus, S.pyogenes, H.flu.

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6
Q

Influenza - Other complications:

A
  1. Rhabdomyolysis.
  2. Myocarditis.
  3. Encephalitis.
  4. Guillain-Barre.
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7
Q

Influenza - Dx:

A

MC diagnosed based on clinical presentation during community outbreaks.

==> If abrupt onset of fever + cough occurs in an adult living in a community with an outbreak ==> 70% sp for influenza.

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8
Q

Influenza - Dx - Seasonal strain of influenza may be detected from …?

A
  1. Sputum, nasal or throat swab.
  2. Or from nasopharyngeal aspirate by rapid antigen test.

==> Se depends on testing kit; may be relatively insensitive (generally 40-70%). Sp is usually 90-95%, but can range from 85-100%.

  1. Can also use molecural methods (90-100% sp), or culture (90-100% sp but slow).

==> Only test if will change clinical care of the patient; Tx should NOT be delayed pending results if there is high suspicion.

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9
Q

Influenza - Tx:

A

Optimal Tx is prevention, with influenza vaccine now universally recommended for ALL PEOPLE >6 MONTHS.

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10
Q

Influenza - Tx - Can consider antiviral therapy for influenza if …?

A

Early in course of illness (<48h) for ambulatory patients who are not significantly ill.

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11
Q

Influenza - Tx - Which pts should receive antiviral therapy?

A

Severely ill pts, hospitalized pts, and those at high risk for complications (pregnant, older than 65y, immune suppressed, and other co-morbidities) should receive antiviral therapy even if initiated after 48h.

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12
Q

Influenza - Tx - Antiviral Tx after 48h in high-risk outpatients?

A

Clinical judgement should drive the decision to start antiviral Tx.

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13
Q

Oseltamivir is administered …?

A

Orally and may result in nausea.

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14
Q

Zanamivir is administered …?

A

By inhalation and is well tolerated, but may result in bronchospasm and should be AVOIDED in susceptible patients, such as those with asthma or COPD.

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15
Q

Peramivir is given by …?

A

Injection and is FDA approved as a single dose for uncomplicated influenza.

==> HOWEVER, for patients who cannot take oral or inhaled drugs, it offers an unproven alternative Tx route for hosp patients.

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16
Q

Pneumonia - Basic info:

A
  1. Remains leading cause of infectious death in USA. 7th overall cause of death.
  2. Mortality highest in older patients and in those with multiple co-morbidities.
  3. S.pneumo and L.pneumophila = Leading bacterial causes of pneumonia-related death.
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17
Q

Pneumonia - Basic info - Microbiology:

A

Altered by host factors (eg age, immunosuppression, alcohol) + geography.

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18
Q

Pneumonia - Basic info - S.pneumoniae remains …?

A

The most commonly diagnosed etiologic agent in studies of community-acquired pneumonia.

==> High-level PCN resistance in S.pneumo is LESS frequent than previously thought (because of revised resistance breakpoints for non-meningeal isolates; approx. 4% in recent US studies).

==> Clinical significance of abx-resistant organisms in pneumonia is debated.

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19
Q

Pneumonia - Basic info - Atypical agents account for …?

A

15-20% of community-acquired pneumonias, and include L.pneumophila, M.pneumoniae, C.pneumoniae.

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20
Q

H.flu, S.aureus, and Gram(-) bacilli …?

A

Each account for 3-10% of community-acquired pneumonias.

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21
Q

Viral pneumonia is UNCOMMON in adults - Etiology:

A
  1. Influenza A and B (MC viral causes).
  2. CMV (immunosuppressed).
  3. Adenovirus, VZV, EBV are rare causes of viral pneumonia in adults.

==> Hantavirus, seen mostly in the southwestern US, is a rare cause of viral pneumonia that quickly evolves to acute resp. distress in previously healthy individuals ==> High mortality rate.

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22
Q

Pneumonia - Fungal infections:

A

RARELY a cause of acute, CAP.

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23
Q

Fungal infections - More than 300 fungi …?

A

Capable of causing lung infection, mostly in immunocompromised patients.

==> Aspergillus spp. and zygomycete organisms (Rhizopus, Mucor spp.) are the leading causes of serious clinical pulm. infection in this population.

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24
Q

Fungal infections - Endemic fungi:

A
  1. H.capsulatum.
  2. B.dermatitidis.
  3. C.immitis.
  4. C.neoformans.

==> Can infect normal hosts and cause lung disease, but greater than 60% of infections are asymptomatic and only a small percentage do NOT resolve spontaneously.

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25
Q

Fungal infection - Candida pneumonia?

A

Very rare cause of pneumonia and should be considered as the causative agent in the PROFOUNDLY immunosuppressed or neutropenic patient.

==> Positive sputum cultures otherwise merely represent upper airway colonization.

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26
Q

H.capsulatum - Presentation:

A

Up to 60% ASYMPTOMATIC. Ohio + Mississippi River valleys.

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27
Q

H.capsulatum - Acute infection:

A
  1. Fever.
  2. Infiltrates.
  3. Pleurisy.
  4. Hilar/mediastinal adenopathy.

==> ARDS, if inoculum sufficiently large ==> Fulminant resp. failure may result.

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28
Q

Progressive disseminated histoplasmosis:

A
  1. May result from primary infection or reactivation.
  2. More common in immunocompromised.
  3. Diffuse LAN + HSM + Adrenal insufficiency may result.
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29
Q

Chronic pulm. histoplasmosis:

A

Often in the setting of COPD.

==> Resembles TB with cavitation.

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30
Q

H.capsulatum - Dx:

A
  1. Culture is the gold standard, but takes 4-6wks.
  2. Histoplasma ANTIGEN may be detected in serum/urine with disseminated disease ==> May cross react with Blastomycosis and Coccidioidomycosis.
  3. Complement fixation of antibody to H.capsulatum may be used, including those with acute pulm. infection (4x rise in titer consistent with acute infection).
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31
Q

H.capsulatum - Tx:

A
  1. Acute infection does not typically require Tx.
  2. Chronic pulm. infections may require treatment with itraconazole.
  3. Disseminated infections treated with itraconazole or amphotericin.

==> High index of suspicion should be held for adrenal insufficiency in disseminated disease.

32
Q

B.dermatitidis - Presentation:

A
  1. Endemic to region between Dakotas and Louisiana.
  2. Disease may be self-limited or require Tx.
  3. Pulm. presentation include infiltrates, nodules, or cavitation.
  4. Skin, bone, and GU tract (prostate and epididymis) most common extrapulmonary sites of infection.
33
Q

B.dermatitidis - Dx:

A
  1. Culture is gold standard.
  2. Visualization of fungi in appropriate clinical setting used to initiate antimicrobial Tx.
  3. Complement fixation is currently neither se nor sp.
34
Q

B.dermatitidis - Tx:

A
  1. ITRACONAZOLE in immune competent patients with mild/moderate disease.
  2. Amphotericin in immune compromised or with CNS involvement.
35
Q

C.immitis - Endemic:

A

To dry regions of Southwestern USA.

36
Q

C.immitis - Presentation - Acute pulm. infection:

A

MC presentation:

  1. Fever + Cough + Extensive alveolar infiltrates.
  2. May be accompanied by MASSIVE hilar/mediastinal LAN.
  3. Cavitation may occur, with hemoptysis.
  4. Erythema nodosum.
37
Q

C.immitis - Presentation - Disseminated disease:

A

Widespread. Skin, muscle, bone, and CNS involvement.

38
Q

C.immitis - Diagnosis:

A
  1. Stain and culture of infected fluid or tissues.
  2. Elevated complement fixation titers to C.immitis ==> These may be followed as markers of disease, with rising titers a poor prognostic sign.
39
Q

C.immitis - Tx:

A
  1. Itraconazole.
  2. Fluconazole.

==> Fluconazole used if CNS involvement or refractory disease.

40
Q

A.fumigatus - Presentation:

A
  1. ABPA.
  2. Aspergilloma.
  3. Invasive aspergillosis.
41
Q

ABPA:

A

A hypersensitivity reaction characterized by asthma and fleeting infiltrates accompanied by eosinophilia.

42
Q

A.fumigatus - Aspergilloma (fungal ball or mycetoma):

A

MC non invasive form, occurring in old scars, cavities, or blebs.

43
Q

Invasive aspergillosis:

A

Usually occurs in immunocompromised, with organ transplant and hematologic malignancies common predisposers.

==> Presents as acute pneumonia with cavitation, then invades locally along with hematogenous dissemination.

44
Q

ABPA - Dx:

A
  1. Positive sputum culture.
  2. Elevated IgE.
  3. Elevated specific antibodies to Aspergillus.
  4. Cutaneous reaction to Aspergillus immunogen.
45
Q

Aspergilloma - Dx:

A

By clinical presentation.

46
Q

Invasive aspergillosis - Dx:

A
  1. Clinical + Microbiologic + Radiographic presentation and CT scan.
  2. Biopsy with culture usually suggested to distinguish from colonization.
  3. Serum GALACTOMANNAN may be elevated.
47
Q

ABPA - Tx:

A

Corticosteroids; role of antifungal Tx UNCLEAR.

48
Q

Aspergilloma - Tx:

A

May require embolization or resection for control of hemoptysis.

==> Otherwise no antifungal Tx is necessary.

49
Q

Invasive aspergillosis - Tx:

A

VORICONAZOLE is the Tx of choice.

50
Q

Pneumonia - Clinical presentation - Classic triad:

A
  1. Cough.
  2. Fever.
  3. New pulm. infiltrate.
51
Q

Pneumonia - What heightens suspicion for atypical bacteria?

A

Although no reliable clinical indicators have been established to differentiate typical pneumonia from atypical pneumonia ==> PURULENT SPUTUM WITHOUT IDENTIFICATION OF A PATHOGENIC ORGANISM ==> Heightens suspicion for Legionella, Mycoplasma, Chlamydophila spp.

52
Q

Certain presentations are associated with specific etiologic agents - S.pneumo:

A

Classically presents with sudden rigor + fever + cough productive of rust-colored sputum.

53
Q

Certain presentations are associated with specific etiologic agents - Legionella:

A

==> May occur sporadically or as part of an outbreak associated with aerosol spread of a contaminated water system.
==> Severe pneumonia with high-spiking fever.

  1. Diarrhea.
  2. Relative bradycardia despite high fevers (in some cases).
  3. Hyponatremia may be more common with Legionella than with other etiologic agents.
54
Q

Certain presentations are associated with specific etiologic agents - Mycoplasma:

A

HALLMARK: Paroxysmal, nonproductive cough, often with minimal findings on CXR. However, CXR may demonstrate diffuse pulm. infiltrates and even effusions.

  1. Bullous myringitis, contrary to lore, is NOT a usual finding in Mycoplasma infection.
  2. The production of cold agglutinins (IgM produced in Mycoplasma infection that reversibly agglutinates RBCs when blood is cooled) may lead to Raynaud phenomenon and even DIGITAL NECROSIS (particularly in patients with SCA).
55
Q

Certain presentations are associated with specific etiologic agents - C.pneumoniae:

A

Results in a typically mild pneumonia that is slowly progressive and only rarely severe.

==> It may follow URTI symptoms (pharyngitis, sinusitis) by 1-2 WEEKS.

==> There is LITTLE clinically to differentiate C.pneumoniae from other causes of pneumonia.

56
Q

MC initial AIDS-defining illness?

A

Pneumonia - With P.jiroveci + S.pneumoniae the leading etiologies.

57
Q

Infiltrates with cavitation or subacute pneumonia, especially in an immunocompromised patient, warrant consideration of …?

A

TB (1-2% of all CAP).

58
Q

Pneumonia - Dx:

A
  1. Chest PE is unreliable to include or to exclude pneumonia diagnosis.
  2. Abnormal VS heighten the likelihood of positive CXR.
  3. CXR is critical to establish infiltrate and to decrease mistaken admin of abx for acute bronchitis.
59
Q

Pneumonia - Dx - Sputum:

A

With more than 25 PMNs and less than 10 epithelial cells/hpf ==> Considered purulent specimen; may adequately reflect pathogen of pneumonia.

60
Q

Pneumonia - Dx - Blood cultures:

A

Considered OPTIONAL but should be obtained in certain patients:

==> Including those with severe pneumonia, cavitary infiltrates, leukopenia, active alc abuse, chronic liver disease, asplenia, positive pneumococcal urinary antigen test, and pleural effusion.

61
Q

Pneumonia - Dx - If significant pleural effusion is seen at presentation?

A

THORACENTESIS with analysis + culture should be performed.

62
Q

Pneumonia - Dx - Cause of pneumonia is considered definitive only if …?

A

Bacteria are isolated from normally sterile space (blood, pleura).

63
Q

Cause is considered probable but NOT definitive if only …?

A

Cultured from sputum, UNLESS sputum grows Legionella, TB, or some fungi.

64
Q

Legionella urinary antigen detects only …?

A

SEROTYPE 1 L.pneumophila.

==> Sputum direct fluorescent antibody less reliable for Legionella spp.

65
Q

Chlamydophila and Mycoplasma infections best diagnosed by …?

A

PCR assay of resp. specimen.

==> Serology unreliable.

66
Q

Pneumonia -Tx - 1st decision:

A

Whether to manage as outpatient or whether hospitalization is appropriate.

67
Q

What will help guide hospitalization?

A

Pneumonia Severity Index (PSI) or CURB-65 score.

==> PSI has higher Se but lower Sp than CURB-65.

68
Q

Hospitalization usually required for …?

A
  1. Patients who have co-morbidities.
  2. Highly abnormal VS.
  3. Hypoxemia.
  4. Lab abnormalities.
  5. Older adults.
69
Q

Pneumonia - Tx - Initial abx choice?

A

Typically empiric and should cover S.pneumo.

==> Should also cover atypical agents and drug-resistant Pneumococcus if patient is severely ill.

70
Q

Pneumonia - Tx - Timely abx admin:

A

Within 6h of initial encounter ==> Correlates with decr. mortality; considered standard of care.

71
Q

Recommended empirical abx for CAP - Outpatient Tx - Previously healthy and no use of antimicrobials within previous 3 months:

A
  1. A macrolide (azithro, clarithro) ==> Strong recommendation.
  2. Doxycycline ==> Weak recommendation.
72
Q

Recommended empirical abx for CAP - Outpatient Tx - Presence of co-morbidities:

  1. Chronic heart, lung, liver, renal disease.
  2. DM.
  3. Alcoholism.
  4. Malignancies.
  5. Asplenia.
  6. Immunosuppressing conditions/Immunosuppressing drugs.
  7. Use of antimicrobials within the previous 3 months (in which case an alternative from a different class should be selected).
A
  1. A resp. FQ (moxi or levo) (STRONG recommendation).

2. A beta-lactam (amoxil/clavulanate, high-dose amoxicillin 1g tid, cefpodoxime, or cefuroxime) + macrolide.

73
Q

Recommended empirical abx for CAP - Outpatient Tx - In regions with a high rate (>25%) of infection with high-level (MIC>16) macrolide-resistant S.pneumo, consider …?

A

Use of alternative agents listed previously in (2) for pts without comorbidities (MODERATE recommendation).

74
Q

Recommended empirical abx for CAP - Inpatients, NON-ICU Tx:

A
  1. Resp. FQ (STRONG recommendation).

2. Beta-lactam (ceftriaxone, cefotaxime, ertapenem) plus a macrolide (STRONG recommendation).

75
Q

Recommended empirical abx for CAP - Inpatient, ICU Tx:

A
  1. A beta-lactam (cefotaxime, ceftriaxone, or ampicillin/sulbactam) + Either azithro or a resp FQ ==> STRONG recommendation.
  2. For PCN-allergic patients ==> a resp. FQ + Aztreonam.
76
Q

Recommended empirical abx for CAP - Special concerns - If there is a high concern for Pseudomonas infection in sick patients:

A
  1. Antipneumococcal, antipseudomonal beta-lactam (Pip/taz, cefepime, imipenem, meropenem) + Either ciproflox or levoflox (750mg).
  2. OR the above beta-lactam + aminoglycoside + resp. FQ (for PCN-allergic, substitute Aztreonam for above beta-lactam) ==> Moderate recommendation.
  3. If CA-MRSA is a consideration, add vanco or linezolid ==> Moderate recommendation.

Internal Medicine (106 decks)

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