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3151 Therapeutics > LRTI (Acute Bronchitis & CAP) > Flashcards

LRTI (Acute Bronchitis & CAP) Flashcards

1
Q

[ACUTE BRONCHITIS]

What is acute bronchitis?

A

Acute cough (usually less than 3 weeks), due to inflammation of the trachea and lower airways

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2
Q

[ACUTE BRONCHITIS]

Patient presents with acute cough, suspected for acute bronchitis

What should be reviewed?

A
  1. Preexisting health conditions
  2. Exposure history
  3. Consideration of differential diagnosis (common cold, cough variant asthma, acute exacerbation of chronic bronchitis in smoker, acute exacerbation, bronchiectasis, acute rhinosinusitis) *diagnosis is CLINICAL
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3
Q

[ACUTE BRONCHITIS]

Is micro biological diagnostic test indicated for acute bronchitis?

A

No, unless signs and symptoms of bacterial infection is present

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4
Q

[ACUTE BRONCHITIS]

Describe the clinical presentation of acute bronchitis

A
  • Starts as a viral URTI
  • Self-limiting
  • Acute cough, less than 3 weeks
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5
Q

[ACUTE BRONCHITIS]

Is antibiotic recommended for acute bronchitis?

A

No

  • Only use Abx if bacterial infection is suspected, and further diagnostics is done to confirm presence of bacterial infection
  • Abx use in acute bronchitis did NOT cause difference in cough resolution
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6
Q

[ACUTE BRONCHITIS]

Counsel on the monitoring for resolution of acute bronchitis

A
  • Cough may last at least 3 weeks
  • Abx will not hasten cough resolution
  • If develop fever, shortness of breath, chest pain, or if cough increases in extent or frequency, or if significant cough persists beyond 3 weeks => see a doctor (*possible bacterial superinfection after a viral infection)
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7
Q

[PNEUMONIA]

What is pneumonia?

A

Infection of the lung parenchyma, due to proliferation of microbial pathogens in the alveolar level

*Bacterial pneumonia is most common (fungal and viral less common)

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8
Q

[PNEUMONIA]

What are some general risk factors for pneumonia?

A
  1. Smoking - suppressed neutrophil function, damaged lung epithelium
  2. Chronic lung condition - COPD, asthma, lung cancer => destroys lung tissue and offers pathogen more niduses for infection
  3. Immune suppression - e.g., HIV, sepsis, glucocorticoids, chemotherapy
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9
Q

[PNEUMONIA]

Describe the pathophysiology of pneumonia

A

Risk factors (e.g., smoking, chronic lung condition, immune suppression) contribute to

  • exposure to pathogen via inhalation, aspiration (e.g., from bacteria oropharyngeal sections), contiguous, hematological mechanisms
  • susceptible host, virulent pathogen
  • proliferation of microbe in lower airways and alveoli
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10
Q
  1. Confirm presence of infection [PNEUMONIA]

Describe the clinical presentations/diagnosis

  • Systemic Presentations
A

General systemic presentations of infection

  • Fever >=38, tachycardia >90, tachypnea >22, hypotention <100, change in mental status
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11
Q
  1. Confirm presence of infection [PNEUMONIA]

Describe the clinical presentations/diagnosis

  • Localized symptoms
A

Localized symptoms

  • Cough, chest pain (pleuritic), SOB, tachypnea >24-25, hypoxia (reduce O2 saturation, may require O2 supplementation)
  • Increased sputum pdn
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12
Q
  1. Confirm presence of infection [PNEUMONIA]

Describe the clinical presentations/diagnosis

  • Physical Examination
A

Physical examination (lung auscultation)

  • Diminished breath sounds over affected area
  • Inspiratory crackles during lung expansion
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13
Q
  1. Confirm presence of infection [PNEUMONIA]

Describe the clinical presentations/diagnosis

  • Radiographic Findings
A

Radiographic findings (CXR, lung CT, lung ultrasonography)

  • Evidence of NEW infiltrates/consolidations (appear as white patches, usually unilateral)
  • CT scan better as can show lung abscess
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14
Q
  1. Confirm presence of infection [PNEUMONIA]

Describe the clinical presentations/diagnosis

  • Lab Findings
A

Lab findings

  • General labs (signs of systemic infection, but NON-SPECIFIC for pneumonia): WBC, neutrophils, CRP, PCT
  • Urinary antigen test - identify exposure to streptococcus pneumonia, or legionella pneumophilia
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15
Q
  1. Confirm presence of infection [PNEUMONIA]

Explain who urinary antigen test is recommended for, and its limitations.

A

Urinary antigen test

Recommended for severe inpatient CAP or hospitalized patients, NOT for outpatient

  • To just give a sense of what might be the pathogen

Limitations:

  • Indicate EXPOSURE to respective pathogens
  • Remain positive for days-weeks despite antibiotic treatment
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16
Q
  1. Identification of pathogens [PNEUMONIA]

What are the 2 cultures used to identify pathogens.

A
  1. Respiratory gram-stain and culture
  • Sputum (low yield, more contamination by oropharyngeal secretions)
  • Lower respiratory tract samples (invasive sampling - BAL, less contamination)
  1. Blood culture
  • to rule out bacteremia (esp for hospitalised patients)
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17
Q
  1. Identification of pathogens [PNEUMONIA]

Explain the significance of WBC, epithelial cells, and bacterial cells findings in a gram-stain culture.

A

WBC - indicate sputum sample

Epithelial cells - indicates that sputum sample is contaminated with oropharyngeal secretions (e.g., from saliva)

Bacteria cells - may be usual colonizer, contamination especially if many diff organisms found

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18
Q
  1. Identification of pathogens [PNEUMONIA]

Based on IDSA guidelines, when should pre-treatment blood and respiratory gram stain and cultures be obtained?

A
  1. For patients with severe CAP (inpatient severe)
  2. For patients with risk factors for drug-resistant pathogens (e.g., MRSA, Pseudomonas aeruginosa) E.g.,:
  • Pt being empirically treated for MRSA or P. aeruginosa
  • Were previously infected with MRSA or P. aeruginosa in the last 1 year
  • Were hospitalized or received parenteral antibiotics in the last 90 days
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19
Q

[PNEUMONIA]

Explain the classification of CAP, HAP, VAP

A

Community-acquired pneumonia (CAP): onset in the community or <48h after hospital admission

Hospital-acquired pneumonia (HAP): Onset >=48h after hospital admission

Ventilator-associated pneumonia (VAP): Onset >=48h after mechanical ventilation

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20
Q

[PNEUMONIA]

Explain why classification of healthcare-associated pneumonia is obsolete

HCAP: onset in the community or <48h after hospital admission AND 1 or more of the following criteria (1. Nursing home 2. Hospitalized >=48h in the last 90 days 3. Wound care/IV antibiotics/chemotherapy in the last 30 days 4. HD patients)

A

HCAP has been incorporated into CAP

  • Because HCAP is a poor predictor of resistant pathogens or worse outcomes
  • HCAP leads to overuse of broad-spectrum antibiotic

Hence, now classified as CAP with emphasis on:

  1. Need for coverage of DRO
  2. De-escalation of tx with negative culture
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21
Q
  1. Confirm presence of infection [CAP]

What are the risk factors for CAP?

How to prevent CAP?

A

Risk factors

  • As per pneumonia (smoking, chronic lung condition, immunosuppression)
  • History of pneumonia

Prevention

  • Smoking cessation
  • Immunization (influenza, pneumococcal - protect against key organism, strep pneumo)
22
Q
  1. Identification of pathogens [CAP]

List the key pathogens for outpatient cases

A

Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)

*If no comorbidities, can just consider strep pneumo

23
Q
  1. Identification of pathogens [CAP]

List the key pathogens for inpatient, non-severe cases

A

Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)

MRSA and Pseudomonas Aeruginosa [based on risk factors]

24
Q
  1. Identification of pathogens [CAP]

List the key pathogens for inpatient, severe cases

A

Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)

MRSA and Pseudomonas Aeruginosa [based on risk factors]

Staphylococcus aureus
Other gram-negative bacilli (Klebsiella pneumonia, Burkholderia pseudomallei)

25
Q
  1. Identification of pathogens [CAP]

What are some other pathogens that should be tested (via PCR etc.) to rule out other causes of infection

A
  • Influenza (esp during circulating season)
  • Covid-19
26
Q
  1. Selection of antimicrobial and regimen [CAP]

Severity of clinical presentation of CAP determines:

A
  • Location of treatment (outpatient VS inpatient)
  • Organisms to be covered
  • Empiric abx selection
  • Route of abx administration
27
Q
  1. Selection of antimicrobial and regimen [CAP]

What are the 3 methods for risk stratification for CAP

A
  1. Pneumonia Severity Index (PSI)
  2. CURB-65 score
  3. IDSA/ATS criteria for severe CAP
28
Q
  1. Selection of antimicrobial and regimen [CAP]

Explain the pneumonia severity index (PSI)

A

PSI
- uses 20 variables to classify into 5 mortality risk classes
- Class I and II: outpatient (=<70)
- Class III: short hospitalization/observation (71-90)
- Class IV and V: inpatient (91-130, >130)

*PSI is preferred over CURB-65 due to better prediction of outcomes, but it is complex to use

29
Q
  1. Selection of antimicrobial and regimen [CAP]

Explain CURB-65 score

A

CURB-65
- 5 variables to stratify CAP patients into 3 mortality risk classes
- Score 0-1: outpatient
- Score 2: inpatient
- Score >=3: inpatient, consider ICU

*Easy to use with readily available parameters

Parameters (1 point each):
- Confusion
- Urea >7mmol/L
- RR >= 30 breaths/min
- BP (SBP <90, DBP =<60)
- 65 years and above

30
Q
  1. Selection of antimicrobial and regimen [CAP]

Explain the IDSA/ATS criteria for severe CAP

A

Severe CAP is defined as 1 or more major criteria OR 3 or more minor criteria

Major criteria:

  • Mechanical ventilation
  • Septic shock requiring vasoactive medications

Minor criteria:

  • RR >= 30 breaths/min
  • Confusion/disorientation
  • Uremia (urea >7mmol/L)
  • PaO2/FiO2 =< 250
  • Multilobar infiltrates
  • Leukopenia (WBC <4 x 10^9)
  • Hypothermia (temp <36dc)
  • Hypotension requiring aggressive fluid resuscitation
31
Q
  1. Selection of antimicrobial and regimen [outpatient CAP]

Recommend empiric regimen for outpatient cases
(no comorbidities)

Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)

A

*All ORAL

Outpatient, no comorbidities (cover Strep pneumo only)
- PO Amoxicillin 1g q8h
- PO Levofloxacin 750mg q24h
- PO Moxifloxacin

32
Q
  1. Selection of antimicrobial and regimen [outpatient CAP]

Recommend empiric regimen for outpatient cases
(with comorbidities)

Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)

A

*All ORAL

Outpatient, with comorbidities (e.g., chronic heart, lung, liver, renal disease, DM, alcoholism, malignancy, asplenia)

  • PO Amox/Clav 625mg q8h or 1g q12h
  • PO Cefuroxime 500mg q12h

+

  • PO Clarithromycin 500mg q12h
  • PO Azithromycin 500mg q24h
  • PO Doxycyline 100mg q12h

OR

  • PO Levofloxacin 750mg q24h
  • PO Moxifloxacin
    *FQs can be used alone
33
Q
  1. Selection of antimicrobial and regimen [outpatient CAP]

Why can’t ciprofloxacin be used for outpatient cases of CAP?

A

Ciprofloxacin does not cover atypicals, does not cover strep pneumoniae

*Not a respiratory quinolone

34
Q
  1. Selection of antimicrobial and regimen [outpatient CAP]

Rationalize the choice between azithromycin, clarithromycin, and doxycyline for atypical cover in CAP

A

Macrolides

  • b/w the macrolides, efficacy and safety is similar
  • Azithromycin is preferred due to single dose (q24h), cheaper, and less CYP inhibitory effect

Between Doxycyline and macrolides

  • choose based on SE profile
  • Doxycyline: esophagitis, phototoxicity
  • Macrolides: QTc prolongation (do not use if >450-500ms)
35
Q
  1. Selection of antimicrobial and regimen [inpatient non-severe CAP]

Recommend empiric regimen for inpatient non-severe cases

*Recommendation without MRSA/P. aeruginosa risk factors:

Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)
MRSA and Pseudomonas Aeruginosa [based on risk factors]

A

*May use IV or PO (depending on pt ability to swallow)

  • PO Amox/Clav 625mg q8h or 1g q12h or IV 1.2g q8h
  • PO/IV Cefuroxime 500mg q12h
  • IV Ceftriaxone 1-2g q24h

+

  • PO/IV Clarithromycin 500mg q12h
  • PO/IV Azithromycin 500mg q24h
  • PO Doxycyline 100mg q12h

OR

  • PO/IV Levofloxacin 750mg q24h
  • PO/IV Moxifloxacin
    *FQs can be used alone
36
Q
  1. Selection of antimicrobial and regimen [inpatient non-severe CAP]

Recommend empiric regimen for inpatient non-severe cases

*Recommendation with MRSA risk factors:

Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)
MRSA and Pseudomonas Aeruginosa [based on risk factors]

What are the MRSA risk factors?

A

MRSA risk factors for inpatient, non-severe CAP:

  • Respiratory isolation of MRSA in last 1y
  • Hospitalization or parenteral antibiotic use in last 90 days AND MRSA PCR screen positive

ADDITIONAL:

  • IV Vancomycin 25-30mg/kg LD, 15mg/kg q8-12h, to achieve AUC/MIC 400-600
  • IV/PO Linezolid 600mg q12h
37
Q
  1. Selection of antimicrobial and regimen [CAP]

Why is Daptomycin not considered for MRSA cover in CAP?

A

Daptomycin is inactivated by lung surfactants, hence not used for pneumonia

38
Q
  1. Selection of antimicrobial and regimen [inpatient non-severe CAP]

Recommend empiric regimen for inpatient non-severe cases

*Recommendation with Pseudomonas risk factors:

Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)
MRSA and Pseudomonas Aeruginosa [based on risk factors]

What are the P. aeruginosa risk factors?

A

Pseudomonas Aeruginosa risk factors for inpatient, non-severe CAP:

  • Respiratory isolation of P. aeruginosa in last 1y

MODIFY REGIMEN:
- IV Piperacillin/Tazobactam 4.5g q6-8h
- IV Ceftazidime 2g q8h
- IV Cefepime 2g q8h
- IV Meropenem 1g q8h
- PO/IV Levofloxacin 750mg q24h

39
Q
  1. Selection of antimicrobial and regimen [SCAP]

What are the 2 antibiotics that can cover Burkholderia psuedomallei
*Impt in inpatient severe CAP

A
  1. Meropenem
  2. Ceftazidime
40
Q
  1. Selection of antimicrobial and regimen [SCAP]

Recommend empiric regimen for inpatient severe cases

Recommend cover for a patient with no MRSA/P. aeruginosa risk factors

Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)
MRSA and Pseudomonas Aeruginosa [based on risk factors]
Staphylococcus aureus
Other gram-negative bacilli (Klebsiella pneumonia, Burkholderia pseudomallei)

A

*Use IV

  • IV Amox/Clav 1.2g q8h

+

  • IV Ceftazidime 2g q8h

+

  • IV Clarithromycin 500mg q12h
  • IV Azithromycin 500mg q24h

OR

  • IV Levofloxacin 750mg q24h
  • IV Moxifloxacin

+

  • IV Ceftazidime 2g q8h
41
Q
  1. Selection of antimicrobial and regimen [SCAP]

Recommend empiric regimen for inpatient severe cases

*Recommendation with MRSA risk factors:

Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)
MRSA and Pseudomonas Aeruginosa [based on risk factors]
Staphylococcus aureus
Other gram-negative bacilli (Klebsiella pneumonia, Burkholderia pseudomallei)

What are the MRSA risk factors?

A

MRSA risk factors for inpatient, severe CAP:

  • Respiratory isolation of MRSA in last 1y
  • Hospitalization or parenteral antibiotic use in last 90 days

ADDITIONAL:

  • IV Vancomycin 25-30mg/kg LD, 15mg/kg q8-12h, to achieve AUC/MIC 400-600
  • IV/PO Linezolid 600mg q12h
42
Q
  1. Selection of antimicrobial and regimen [SCAP]

Recommend empiric regimen for inpatient severe cases

*Recommendation with P. aeruginosa risk factors:

Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)
MRSA and Pseudomonas Aeruginosa [based on risk factors]
Staphylococcus aureus
Other gram-negative bacilli (Klebsiella pneumonia, Burkholderia pseudomallei)

What are the P. aeruginosa risk factors?

A

P. aeruginosa risk factors for inpatient, severe CAP:
- Respiratory isolation of P. aeruginosa in last 1y
- Hospitalization or parenteral antibiotic use in last 90 days

MODIFY REGIMEN (local regimen does not need modification):
- Ceftazidime
- Levofloxacin

43
Q
  1. Selection of antimicrobial and regimen [CAP]

When is anaerobic cover required?

What antibiotics can be considered if anaerobic cover is required?

A

Anaerobic cover is indicated in RADIOLOGY investigations report the following:

  • Lung abscess
  • Empyema

=> Collection of pus suggest anaerobic environment

Antibiotic selection:

  • PO/IV Metronidazole (IV 500mg q6-12h, PO 400mg q8-12h)
  • PO/IV Clindamycin 300-600mg q6-8h

In regimen alr:
- Moxifloxacin
- Amox/Clav
- Meropenem

44
Q
  1. Selection of antimicrobial and regimen [CAP]

Describe influenza management in CAP

A

*Do influenza PCR

If suspicious for influenza,

  • Add empiric Oseltamivir
  • Initiate Oseltamivir asap (best within first 48h, up to 5 days) of symptom onset

For patients with positive influenza PCR,

  • Complete 5 day course of Oseltamivir (75mg BD x5d)
  • Consider discontinuation of antibiotic at 48-72h if no evidence of bacterial pathogen (negative bacteria culture, low PCT level, early clinical stability) => means infection is caused by influenza
45
Q
  1. Selection of antimicrobial and regimen [CAP]

Why is respiratory FQs not 1st line for CAP?

(To use the B-lactam + macrolide combi as 1st line instead)

A

Adverse effects:
- GI-related: N&V, diarrhea
- Tendonitis, tendon rupture
- Peripheral neuropathy
- QTc prolongation
- CNS disturbances – headache, dizziness, light-headedness
- Dysglycemia (hypoglycemia, hyperglycemia)
- Aortic dissections, ruptures of aortic aneurysm
- Increased risk of C. diff colitis
- Phototoxicity
- Arthropathy

Resistance:

  • Development of resistance with overuse
  • Collateral damage (resistance to 3rd gen cephalosporins)

Preserve activity for other gram-negative infections:

  • Preserve for use as alternative pseudomonas cover with severe penicillin allergies
  • Only PO option for pseudomonas

Delay diagnosis of tuberculosis:

  • Consider differential diagnosis for TB, FQs have activity against TB and may delay diagnosis due to improper sputum/stain/smear obtained

Undesirable as monotherapy if TB:

  • If truly TB, FQ should not be used as monotherapy
46
Q
  1. Selection of antimicrobial and regimen [CAP]

When should adjunctive corticosteroid therapy be considered in CAP?

A

Adjunctive corticosteroid - decrease inflammation in the lungs
E.g., IV hydrocortisone

Place in therapy:

  • Add ONLY IF shock refractory to fluid resuscitation and vasopressor support [SEVERE CAP, in ICU]
47
Q
  1. Selection of antimicrobial and regimen [CAP]

Discuss when and how deescalation / IV to oral conversion of CAP antibiotic regimen can be done

A

When to de-escalate?

  • Pt is hemodynamically stable
  • Pt has improved clinically
  • Pt able to ingest oral medication

How to de-escalate?

=> Positive culture

  • Use AST to guide selection of narrower spectrum and/or PO antibiotics

=> If no positive culture

  • De-escalate empiric cover for MRSA, pseudomonas aeruginosa, Burkholderia pseudomallei after 48h if pathogen not isolated and pt is improving
  • IV to oral: use same antibiotic or another antibiotic from same class
48
Q
  1. Selection of antimicrobial and regimen [CAP]

If patient has no positive culture, but is improving, de-escalation can be done. What must the antibiotics still cover?

A

Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)
Staphylococcus aureus
Klebsiella

E.g., Oral Augmentin + Oral Clarithromycin
E.g., Oral Levofloxacin (if still need pseudomonas cover)

49
Q
  1. Selection of antimicrobial and regimen [CAP]

What is the treatment duration for CAP?

A

Minimum 5 days therapy
7 days if suspected/proven MRSA or Pseudomonas Aeruginosa

*Provided pt achieved clinical stability:
- Resolution of vital signs abnormalities
- Ability to maintain oral intake
- Baseline mental status

*Most patient should achieve clinical stability within first 48-72h

50
Q
  1. Selection of antimicrobial and regimen [CAP]

When might longer treatment duration be required for CAP?

A

Longer courses of therapy for:

  • CAP complicated with other deep-seated infections (e.g., meningitis, lung abscess) ~2-3 weeks
  • Infection with other less common pathogens
    => Burkholderia pseudomallei ~3-6 weeks
    => TB ~6 months
    => Endemic fungi ~3-6 weeks
51
Q
  1. Monitor response [CAP]
    - Involves therapeutic response + ADRs

How is therapeutic response monitored?

A
  • Most patients achieve clinical stability within 48-72h
  • Elderly pt and those with multiple comorbidities may take longer (4-5 days)
  • Do not escalate Abx in the first 72h (unless 1. Culture-directed, or 2. Significant clinical deterioration)
  • Radiographic improvement lags behind clinical improvement for resolution (takes 6weeks to a few months, hence only repeat if clinical deterioration and suspect new pneumonia/spread)
  • No need to repeat microbiological test (clinical improvement is sufficient)

3151 Therapeutics (12 decks)

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