LRTI (Acute Bronchitis & CAP) Flashcards
[ACUTE BRONCHITIS]
What is acute bronchitis?
Acute cough (usually less than 3 weeks), due to inflammation of the trachea and lower airways
[ACUTE BRONCHITIS]
Patient presents with acute cough, suspected for acute bronchitis
What should be reviewed?
- Preexisting health conditions
- Exposure history
- Consideration of differential diagnosis (common cold, cough variant asthma, acute exacerbation of chronic bronchitis in smoker, acute exacerbation, bronchiectasis, acute rhinosinusitis) *diagnosis is CLINICAL
[ACUTE BRONCHITIS]
Is micro biological diagnostic test indicated for acute bronchitis?
No, unless signs and symptoms of bacterial infection is present
[ACUTE BRONCHITIS]
Describe the clinical presentation of acute bronchitis
- Starts as a viral URTI
- Self-limiting
- Acute cough, less than 3 weeks
[ACUTE BRONCHITIS]
Is antibiotic recommended for acute bronchitis?
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
[ACUTE BRONCHITIS]
Counsel on the monitoring for resolution of acute bronchitis
- 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)
[PNEUMONIA]
What is pneumonia?
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)
[PNEUMONIA]
What are some general risk factors for pneumonia?
- Smoking - suppressed neutrophil function, damaged lung epithelium
- Chronic lung condition - COPD, asthma, lung cancer => destroys lung tissue and offers pathogen more niduses for infection
- Immune suppression - e.g., HIV, sepsis, glucocorticoids, chemotherapy
[PNEUMONIA]
Describe the pathophysiology of pneumonia
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
- Confirm presence of infection [PNEUMONIA]
Describe the clinical presentations/diagnosis
- Systemic Presentations
General systemic presentations of infection
- Fever >=38, tachycardia >90, tachypnea >22, hypotention <100, change in mental status
- Confirm presence of infection [PNEUMONIA]
Describe the clinical presentations/diagnosis
- Localized symptoms
Localized symptoms
- Cough, chest pain (pleuritic), SOB, tachypnea >24-25, hypoxia (reduce O2 saturation, may require O2 supplementation)
- Increased sputum pdn
- Confirm presence of infection [PNEUMONIA]
Describe the clinical presentations/diagnosis
- Physical Examination
Physical examination (lung auscultation)
- Diminished breath sounds over affected area
- Inspiratory crackles during lung expansion
- Confirm presence of infection [PNEUMONIA]
Describe the clinical presentations/diagnosis
- Radiographic Findings
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
- Confirm presence of infection [PNEUMONIA]
Describe the clinical presentations/diagnosis
- Lab Findings
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
- Confirm presence of infection [PNEUMONIA]
Explain who urinary antigen test is recommended for, and its limitations.
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
- Identification of pathogens [PNEUMONIA]
What are the 2 cultures used to identify pathogens.
- Respiratory gram-stain and culture
- Sputum (low yield, more contamination by oropharyngeal secretions)
- Lower respiratory tract samples (invasive sampling - BAL, less contamination)
- Blood culture
- to rule out bacteremia (esp for hospitalised patients)
- Identification of pathogens [PNEUMONIA]
Explain the significance of WBC, epithelial cells, and bacterial cells findings in a gram-stain culture.
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
- Identification of pathogens [PNEUMONIA]
Based on IDSA guidelines, when should pre-treatment blood and respiratory gram stain and cultures be obtained?
- For patients with severe CAP (inpatient severe)
- 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
[PNEUMONIA]
Explain the classification of CAP, HAP, VAP
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
[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)
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:
- Need for coverage of DRO
- De-escalation of tx with negative culture
- Confirm presence of infection [CAP]
What are the risk factors for CAP?
How to prevent CAP?
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)
- Identification of pathogens [CAP]
List the key pathogens for outpatient cases
Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)
*If no comorbidities, can just consider strep pneumo
- Identification of pathogens [CAP]
List the key pathogens for inpatient, non-severe cases
Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)
MRSA and Pseudomonas Aeruginosa [based on risk factors]
- Identification of pathogens [CAP]
List the key pathogens for inpatient, severe cases
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)
- Identification of pathogens [CAP]
What are some other pathogens that should be tested (via PCR etc.) to rule out other causes of infection
- Influenza (esp during circulating season)
- Covid-19
- Selection of antimicrobial and regimen [CAP]
Severity of clinical presentation of CAP determines:
- Location of treatment (outpatient VS inpatient)
- Organisms to be covered
- Empiric abx selection
- Route of abx administration
- Selection of antimicrobial and regimen [CAP]
What are the 3 methods for risk stratification for CAP
- Pneumonia Severity Index (PSI)
- CURB-65 score
- IDSA/ATS criteria for severe CAP
- Selection of antimicrobial and regimen [CAP]
Explain the pneumonia severity index (PSI)
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
- Selection of antimicrobial and regimen [CAP]
Explain CURB-65 score
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
- Selection of antimicrobial and regimen [CAP]
Explain the IDSA/ATS criteria for severe CAP
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
- Selection of antimicrobial and regimen [outpatient CAP]
Recommend empiric regimen for outpatient cases
(no comorbidities)
Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)
*All ORAL
Outpatient, no comorbidities (cover Strep pneumo only)
- PO Amoxicillin 1g q8h
- PO Levofloxacin 750mg q24h
- PO Moxifloxacin
- Selection of antimicrobial and regimen [outpatient CAP]
Recommend empiric regimen for outpatient cases
(with comorbidities)
Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Mycoplasma, Chlamydia, Legionella)
*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
- Selection of antimicrobial and regimen [outpatient CAP]
Why can’t ciprofloxacin be used for outpatient cases of CAP?
Ciprofloxacin does not cover atypicals, does not cover strep pneumoniae
*Not a respiratory quinolone
- Selection of antimicrobial and regimen [outpatient CAP]
Rationalize the choice between azithromycin, clarithromycin, and doxycyline for atypical cover in CAP
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)
- 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]
*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
- 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?
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
- Selection of antimicrobial and regimen [CAP]
Why is Daptomycin not considered for MRSA cover in CAP?
Daptomycin is inactivated by lung surfactants, hence not used for pneumonia
- 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?
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
- Selection of antimicrobial and regimen [SCAP]
What are the 2 antibiotics that can cover Burkholderia psuedomallei
*Impt in inpatient severe CAP
- Meropenem
- Ceftazidime
- 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)
*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
- 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?
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
- 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?
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
- Selection of antimicrobial and regimen [CAP]
When is anaerobic cover required?
What antibiotics can be considered if anaerobic cover is required?
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
- Selection of antimicrobial and regimen [CAP]
Describe influenza management in CAP
*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
- 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)
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
- Selection of antimicrobial and regimen [CAP]
When should adjunctive corticosteroid therapy be considered in CAP?
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]
- Selection of antimicrobial and regimen [CAP]
Discuss when and how deescalation / IV to oral conversion of CAP antibiotic regimen can be done
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
- 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?
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)
- Selection of antimicrobial and regimen [CAP]
What is the treatment duration for CAP?
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
- Selection of antimicrobial and regimen [CAP]
When might longer treatment duration be required for CAP?
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
- Monitor response [CAP]
- Involves therapeutic response + ADRs
How is therapeutic response monitored?
- 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)
