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Diagnosis and Treatment of Adults with Community-acquired Pneumonia: 2019 Clinical Practice Guidelines

14 Nov 2019 12:48 PM | MSHP Office (Administrator)

Authors: Mary Thorne, PharmD, PGY1 Pharmacy Resident and Kathryn Lincoln PharmD, BCPS, BCIDP, Clinical Pharmacist – Infectious Diseases, Olathe Medical Center

Learning Objectives

  1. Provide background information on community acquired pneumonia (CAP)
  2. Explain the updated guidelines and the rationale behind the recommendations
  3. Compare the 2007 guideline to current guideline recommendations
  4. Summarize current recommendations for management of CAP

Introduction

The American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA) developed updated guidelines for community-acquired pneumonia (CAP) and were released in October this year. The 2007 CAP guidelines were preceded by the 2005 ATS Guidelines for the Management of Adults with Hospital-acquired (HAP), Ventilator-associated (VAP), and Healthcare-associated Pneumonia (HCAP). In 2016, IDSA and ATS released Management of Adults with Hospital-acquired and Ventilator-associated Pneumonia, leaving out HCAP. Since their release, there has been controversy and much debate about how to manage patients that may have community-acquired pneumonia, but are more at risk than the general population for multi-drug resistant organisms (MDRO). More literature has become available for the management of CAP since the 2007 guidelines, including patients at risk for MDRO.

Community-acquired pneumonia is defined as pneumonia that is acquired outside of the hospital setting. Common pathogens for CAP include Haemophilus influenza, Legionella species, Chlamydophila pneumoniae, Moraxella catarrhalis, Streptococcus pneumoniae, Staphylococcus aureus, and Mycoplasma pneumoniae.

Recommendation #1

In adults with CAP, recommend against obtaining sputum gram stain and culture routinely in adults with CAP managed in the outpatient setting (strong recommendation, very low quality of evidence).

Pre-treatment gram stain and culture of respiratory secretions should be obtained for adult patients with CAP in the hospital setting who are classified as severe CAP. Severe CAP being patients who were empirically treated for MRSA or P. aeruginosa, previously infected with MRSA or P. aeruginosa, hospitalized and received parenteral antibiotics in the past 90 days.

Studies did not show improved patient outcomes when evaluating sputum gram stain and culture either in combination or alone. Research is still needed for guidance on rapid, cost effective diagnostics to help identify organisms causing CAP and improve targeted therapy when there are risk factors for MRSA and P. aeruginosa.

Recommendation #3

In adults with CAP, recommend against routinely testing urine antigens in adults with CAP, except patients with severe CAP or in cases where indicated by epidemiological factors such as association with a Legionella outbreak or recent travel (conditional recommendation, low quality of evidence).

Randomized trials have not shown benefit for urinary antigen testing for S. pneumoniae and Legionella. There is concern that narrowing therapy in response to positive urinary antigen tests could lead to increased risk of clinical relapse.

Recommendation #4

In adults with CAP, recommend during influenza season, test for influenza with a rapid influenza molecular assay (strong recommendation, moderate quality of evidence).

During periods of high influenza activity, it is beneficial to utilize a rapid influenza test. Testing provides both therapeutic and infection control benefits.

Recommendation #5

In adults with CAP, recommend empiric antibiotic therapy initiated in adults with clinically suspected and radiographically confirmed CAP regardless of initial serum procalcitonin (strong recommendation, moderate quality of evidence).

Procalcitonin is used to guide de-escalation, discontinuation and duration of antibiotics in patients with lower respiratory infections. The sensitivity of procalcitonin for detecting bacterial infection ranges from 38% to 91%. This test alone cannot be used to justify withholding antibiotics from patients with CAP.

There is not an established procalcitonin threshold for determining viral versus bacterial pathogens in hospitalized patients with CAP. However, there is a strong correlation with a higher procalcitonin and the probability of a bacterial infection.

Recommendation #6

Clinicians should use a prediction rule for prognosis, preferentially the Pneumonia Severity Index (PSI) (strong recommendation, moderate quality of evidence).

PSI should be used as a supplement to clinical judgment. There is evidence confirming the safety and effectiveness of using PSI in addition to clinical judgment as a prognostic tool. PSI is a prognostic model in immunocompetent patients with pneumonia using demographic and clinical variables from the time of diagnosis to predict 30-day mortality.


Recommendation #8

In the outpatient setting, antibiotics are recommended for empiric treatment of CAP in adults.  For healthy outpatient adults without comorbidities or risk factors for antibiotic resistant, the following is recommended: 

  • Amoxicillin 1g PO TID or
  • Doxycycline 100mg PO BID or
  • Macrolide: only in areas with pneumococcal resistance to macrolides < 25%
    • Azithromycin 500mg on first day then 250mg daily

Outpatient adults with comorbidities such as chronic heart, lung, liver, or renal disease, diabetes mellitus, alcoholism, malignancy, or asplenia, the treatment options include monotherapy with a respiratory fluoroquinolone or combination therapy with a beta lactam plus a macrolide or a beta lactam plus doxycycline. There is limited evidence regarding the superiority or equivalency of antibiotic regimens for the treatment of CAP. 


Recommendation #9

For inpatient adults with non-severe CAP without risk factors for MRSA or P. aeruginosa, treatment options include monotherapy with a respiratory fluoroquinolone or combination therapy of a beta lactam plus a macrolide or combination of beta lactam plus doxycycline.

For inpatient adults with severe CAP without risk factors for MRSA or P. aeruginosa, treatment recommendation includes a beta lactam plus a macrolide or a beta lactam plus a respiratory fluoroquinolone.

In the absence of RCTs evaluating therapeutic alternatives in severe CAP, the evidence is from observational studies. The use of fluoroquinolones as monotherapy in severe CAP has not been well studied. There is also limited studies for the combination of a β-lactam and doxycycline in severe CAP patients. These treatment strategies are not recommended as empiric therapy for severe CAP.


Recommendation #10

In the inpatient setting, suggest not routinely adding anaerobic coverage for suspected aspiration pneumonia unless lung abscess or empyema is suspected (conditional recommendation very low quality of evidence).

Older studies showed high rates of isolated anaerobic organisms in patients with aspiration pneumonia. However, more recent studies show that anaerobes are uncommon in hospitalized patients who are suspected to have aspiration pneumonia.

Aspiration is a common occurrence and it is difficult to provide a true rate of aspiration pneumonia. Aspiration pneumonitis is when patients aspirate their gastric contents. More recent studies have suggested that anaerobes do not impact the causation and disease state of acute aspiration pneumonia.

Recommendation #11

Recommend abandoning use of the prior categorization of healthcare-associated pneumonia (HCAP) to guide selection of extended antibiotic coverage in adults with CAP (strong recommendation, moderate quality of evidence).

If there are locally validated risk factors for the presence of MRSA or P. aeruginosa, clinicians should empirically cover for MRSA or P. aeruginosa in adults with CAP. HCAP was introduced due to studies showing a higher prevalence drug resistant pathogens. More recent studies have shown there is not a predicted higher prevalence of drug resistant pathogens when using the factors that define HCAP. The recommendation to abandon the category of HCAP is based on high-quality studies of patient outcomes.

In most settings, studies have shown there is not a predicted higher prevalence of antibiotic-resistant pathogens, when using the factors that define HCAP. Patient outcomes have not improved despite a large increase in the use of broad spectrum antibiotics. Prior isolation of MRSA or P. aeruginosa is a strong risk factor when assessing a patient’s risk of having a respiratory infection with either MRSA or P. aeruginosa.  

Recommendation #12

Recommend not routinely using corticosteroids in adults with non-severe or severe CAP (strong recommendation, high quality of evidence).

In patients with non-severe CAP, there is no evidence for mortality or organ failure benefit with the use of corticosteroids. There is limited data for the use of corticosteroids in patients with severe CAP. The risks of corticosteroids are hyperglycemia primarily, possibly increased rates of re-hospitalization and the potential for more complications.


Recommendation #13

Recommend anti-influenza treatment be prescribed for adults with CAP who test positive for influenza in the inpatient and outpatient setting, independent of duration of illness before diagnosis (strong recommendation, moderate quality of evidence).

Clinical trials have not evaluated the effect of anti-influenza treatment in adult patients with influenza pneumonia. In the outpatient setting, it is unclear whether or not there is benefit to using anti-influenza treatment for patients who have tested positive for the influenza virus. 

Recommendation #14

Recommend that standard antibacterial treatment be initially prescribed for adults with clinical and radiographic evidence of CAP who test positive for influenza in the inpatient and outpatient settings (strong recommendation, low quality of evidence).

A bacterial pneumonia infection can overlap with an active influenza viral infection. In patients recovering from a primary influenza infection, bacterial pneumonia may present later on, as worsening of symptoms. Patients are at risk for a concurrent infection of S. aureus bacterial pneumonia associated with influenza. The recommendation to treat patients with an antibacterial agent is based on the current evidence suggesting that bacterial co-infections with influenza can become complicated.

Recommendation #15

The duration of antibiotic therapy should be guided by a validated measure of clinical stability and antibiotic therapy should be continued until the patient achieves stability and for no less than a total of five days (strong recommendation, moderate quality of evidence).

There are a few randomized trials addressing the appropriate duration for the treatment of patients with CAP. Despite limited data supporting a five-day treatment duration, it is recommended to treat patients for a minimum of five days even if a patient is clinically stable before five days. Clinical stability is the resolution of vital sign abnormalities such as, heart rate, respiratory rate, blood pressure, oxygen saturation, and temperature.

Recommendation #16

In adults with CAP whose symptoms have resolved within 5 to 7 days, we suggest not routinely obtaining follow-up chest imaging (conditional recommendation, low quality of evidence). 

Data is limited when evaluating the utility of reimaging patients with pneumonia. More research may help to clarify any potential benefit to patients who need further radiology imaging after initial treatment.


Summary

Recommend abandoning use of HCAP to guide selection of extended antibiotic coverage in adults with CAP. Emphasis on local epidemiology and validated risk factors to determine need for MRSA or P. aeruginosa coverage. For standard empiric treatment of severe CAP, stronger evidence is in favor of β-lactam plus macrolide combination compared to β-lactam plus fluoroquinolone. 


References

  1. Metlay JP, Waterer GW, Long AC, et al. Diagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019;200(7):e45-e67.
  2. Self WH, Balk RA, Grijalva CG, Williams DJ, Zhu Y, Anderson EJ, et al. Procalcitonin as a marker of etiology in adults hospitalized with community-acquired pneumonia. Clin Infect Dis 2017;65:183–190.
  3. El-Solh AA, Pietrantoni C, Bhat A, Aquilina AT, Okada M, Grover V, et al. Microbiology of severe aspiration pneumonia in institutionalized elderly. Am J Respir Crit Care Med 2003;167:1650–1654
  4. Marik PE, Careau P. The role of anaerobes in patients with ventilator associated pneumonia and aspiration pneumonia: a prospective study. Chest 1999;115:178–183 Intensive Care Med 1993;19:279–284.
  5. Kollef MH, Shorr A, Tabak YP, Gupta V, Liu LZ, Johannes RS. Epidemiology and outcomes of health-care-associated pneumonia: results from a large US database of culture-positive pneumonia. Chest 2005;128:3854–3862
  6. Attridge RT, Frei CR, Pugh MJ, Lawson KA, Ryan L, Anzueto A, et al. Health care-associated pneumonia in the intensive care unit: guideline-concordant antibiotics and outcomes. J Crit Care 2016; 36:265–271.
  7. Attridge RT, Frei CR, Restrepo MI, Lawson KA, Ryan L, Pugh MJ, et al. Guideline-concordant therapy and outcomes in healthcare associated pneumonia. Eur Respir J 2011;38:878–887.


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