Community-Acquired Pneumonia: ATS/IDSA Guidelines Update

Author: Brit Long, MD (@long_brit, EM Attending Physician, San Antonio, TX) // Reviewed by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital)

Emergency clinicians frequently evaluate and manage patients with community-acquired pneumonia (CAP). Unfortunately, the last set of guidelines from the American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA) is over 10 years old. With several recent studies impacting our diagnostic and therapeutic approach for CAP, the American Journal of Respiratory and Critical Care Medicine just released a set of updated guidelines.

This post will take you through the relevant ED recommendations on testing, disposition, and antibiotic therapy. For more, see the open access article at ATS Journals.

The key changes between the 2007 and 2019 ATS/IDSA Guidelines are displayed in Table 2 of the open access article:

Guidelines also breakdown patients with severe CAP, defined by either one major criterion or > 3 minor criteria, in Table 1 of the article:

And now, on to the recommendations…

Recommendations:

1. Do not routinely obtain sputum Gram stain and culture in adults with CAP managed as outpatients (strong recommendation, very low quality of evidence).

However, they should be obtained before treatment in admitted adults with CAP for those with severe CAP OR are being treated for MRSA or P. aeruginosa (strong recommendation, very low quality of evidence), were previously infected with MRSA or P. aeruginosa (conditional recommendation, very low quality of evidence), or were hospitalized and received parenteral antibiotics in the last 90 days (conditional recommendation, very low quality of evidence).

2. Do not obtain blood cultures for patients with CAP managed as outpatients (strong recommendation, very low quality of evidence), and do not routinely obtain blood cultures in those admitted (conditional recommendation, very low quality of evidence).

Blood cultures should be obtained in those with severe CAP (strong recommendation, very low quality of evidence); OR are being treated for MRSA or P. aeruginosa (strong recommendation, very low quality of evidence), were previously infected with MRSA or P. aeruginosa (conditional recommendation, very low quality of evidence), or were hospitalized and received parenteral antibiotics in the last 90 days (conditional recommendation, very low quality of evidence).

3. Do not routinely test for urine pneumococcal antigen in adults with CAP (conditional recommendation, low quality of evidence), except in those with severe CAP (conditional recommendation, low quality of evidence).

Do not routinely test for Legionella antigen in CAP except in cases with epidemiological factors or severe CAP (conditional recommendation, low quality of evidence).

Test for Legionella urinary antigen and collect lower respiratory tract secretions for culture or nucleic acid amplification testing (NAAT) in severe CAP (conditional recommendation, low quality of evidence).

4. If influenza is present in the community, test for influenza with rapid influenza molecular assay (NAAT), rather than an antigen test (strong recommendation, moderate quality of evidence).

5. Start antibiotics in patients with clinically suspected or radiographically confirmed CAP, regardless of the serum procalcitonin (PCT) level (strong recommendation, moderate quality of evidence).

6. With clinical judgement, use a validated clinical prediction rule for prognosis and to determine need for hospitalization. Guidelines preferentially recommend the Pneumonia Severity Index (PSI) (strong recommendation, moderate quality of evidence) over the CURB-65 tool (confusion, urea level, respiratory rate, blood pressure, and age ≥65) (conditional recommendation, low quality of evidence).

7.  For patients with hypotension needing vasopressors or respiratory failure needing mechanical ventilation, admit to the ICU (strong recommendation, low quality of evidence).

Otherwise, use the IDSA/ATS 2007 minor severity criteria (above) with clinical judgement to determine need for higher level of care (conditional recommendation, low quality of evidence).

8. Regarding antibiotics for otherwise healthy adults without comorbidities or risk for resistant pathogens, use:

• Amoxicillin 1 g three times daily (strong recommendation, moderate quality of evidence), or

• Doxycycline 100 mg twice daily (conditional recommendation, low quality of evidence), or

• Macrolide (azithromycin 500 mg on first day then 250 mg daily or clarithromycin 500 mg twice daily or clarithromycin extended release 1,000 mg daily) only in areas with pneumococcal resistance to macrolides <25% (conditional recommendation, moderate quality of evidence).

For adults with comorbidities (chronic heart, lung, liver, or renal disease; diabetes mellitus; alcoholism; malignancy; or asplenia) who may be managed as outpatients, use:

• Combination therapy:

  • Amoxicillin/clavulanate 500 mg/125 mg three times daily, or amoxicillin/clavulanate 875 mg/125 mg twice daily, or 2,000 mg/125 mg twice daily, or a cephalosporin (cefpodoxime 200 mg twice daily or cefuroxime 500 mg twice daily); AND

  • Macrolide (azithromycin 500 mg on first day then 250 mg daily, clarithromycin [500 mg twice daily or extended release 1,000 mg once daily]) (strong recommendation, moderate quality of evidence for combination therapy), or doxycycline 100 mg twice daily (conditional recommendation, low quality of evidence for combination therapy); OR

• Monotherapy:

  • Respiratory fluoroquinolone (levofloxacin 750 mg daily, moxifloxacin 400 mg daily, or gemifloxacin 320 mg daily) (strong recommendation, moderate quality of evidence).

9. For admitted patients with nonsevere CAP and no risk factors for MRSA or P. aeruginosa, use the following:

• Combination therapy with a β-lactam (ampicillin + sulbactam 1.5–3 g every 6 h, cefotaxime 1–2 g every 8 h, ceftriaxone 1–2 g daily, or ceftaroline 600 mg every 12 h) and a macrolide (azithromycin 500 mg daily or clarithromycin 500 mg twice daily) (strong recommendation, high quality of evidence), or

• Monotherapy with a respiratory fluoroquinolone (levofloxacin 750 mg daily, moxifloxacin 400 mg daily) (strong recommendation, high quality of evidence).

A third option for adults with CAP who have contraindications to both macrolides and fluoroquinolones is:

• Combination therapy with a β-lactam (ampicillin + sulbactam, cefotaxime, ceftaroline, or ceftriaxone, doses as above) and doxycycline 100 mg twice daily (conditional recommendation, low quality of evidence).

9.2 For admitted patients with severe CAP but no risk factors for MRSA or P. aeruginosa, use:

• A β-lactam plus a macrolide (strong recommendation, moderate quality of evidence); or

• A β-lactam plus a respiratory fluoroquinolone (strong recommendation, low quality of evidence).

10. Do not routinely add anaerobic coverage for suspected aspiration pneumonia, unless a lung abscess or empyema is suspected (conditional recommendation, very low quality of evidence).

11. Do not use the prior categorization of healthcare-associated pneumonia (HCAP) in determining need for extended antibiotic coverage in admitted patients (strong recommendation, moderate quality of evidence).

Only empirically cover MRSA or P. aeruginosa in admitted patients if locally validated risk factors for either pathogen are present (strong recommendation, moderate quality of evidence). MRSA empiric treatment options include vancomycin (15 mg/kg every 12 h, adjust based on levels) or linezolid (600 mg every 12 h).  P. aeruginosa therapies include piperacillin-tazobactam (4.5 g every 6 h), cefepime (2 g every 8 h), ceftazidime (2 g every 8 h), aztreonam (2 g every 8 h), meropenem (1 g every 8 h), or imipenem (500 mg every 6 h).

If covering empirically for MRSA or Pseudomonas but epidemiological data are not available, continue coverage while obtaining cultures to determine whether these microbes are present (strong recommendation, low quality of evidence).

12. Do not routinely use steroids in adults with nonsevere CAP (strong recommendation, high quality of evidence).

Do not routinely use steroids in those with severe CAP (conditional recommendation, moderate quality of evidence).

Do not routinely use steroids in those with severe influenza pneumonia (conditional recommendation, low quality of evidence).

The ATS/IDSA CAP guidelines endorse the SCC recommendations on using steroids in patients with CAP and refractory septic shock.

13. Use anti-influenza therapy in those admitted patients with CAP who test positive for influenza (strong recommendation, moderate quality of evidence).

Prescribe anti-influenza therapy in patients with CAP managed as outpatients who test positive for influenza (conditional recommendation, low quality of evidence).

14. Use standard antibiotic therapy for adults with clinical and radiographic evidence of CAP who test positive for influenza, whether admitted or managed as an outpatient (strong recommendation, low quality of evidence).

15. The duration of antibiotic therapy should be guided by clinical stability (normal VS, PO tolerant, normal mental status), and therapy should be continued until the patient is stable and for no less than 5 days (strong recommendation, moderate quality of evidence).

16. In adults whose symptoms have resolved in 5-7 days, do not routinely obtain follow-up chest imaging (conditional recommendation, low quality of evidence).