Updated CAP Guidelines Narrows the Scope

The newly published guidelines answer 16 core questions about the diagnosis and treatment of CAP in adults. The guidelines are more narrow in scope than previous versions and focus primarily on the care of a patient with active pneumonia.

After several years of delays, the updated guidelines for Community Acquired Pneumonia (CAP) have been released by the American Thoracic Society and the Infectious Diseases Society of America. The newly published guidelines answer 16 core questions about the diagnosis and treatment of CAP in adults. The guidelines are more narrow in scope than previous versions, and focus primarily on the care of a patient with active pneumonia.

Cultures have long held a prominent role in diagnosing infectious diseases. The 2019 CAP guidelines, however, do not recommend obtaining sputum or blood cultures for those being treated as an outpatient. Cultures should only be obtained in hospitalized patients who have severe CAP, are intubated, who are receiving empiric coverage for methicillin resistant S. aureus (MRSA) or P. aeruginosa, or who have been hospitalized and/or received IV antibiotics in the past 90 days. The guidelines cite the overall poor yield of sputum and subsequent limited impact on patient care as rationale for minimizing those for whom cultures should be obtained. Similarly, blood cultures, though commonly obtained, are positive in less than 9% of inpatients and less than 2% of outpatients with non-severe CAP. Legionella and Pneumococcal urinary antigen tests should only be performed in patients with severe CAP, unless local outbreaks or recent travel support use of the Legionella urinary antigen test. Procalcitonin is not recommended as a tool to help diagnose CAP, but the authors cite the need for additional research into its role in CAP.

Relatively few changes were made to the treatment recommendations. Risk factors for MRSA and P. aeruginosa occur throughout the recommendations. These risk factors include a prior respiratory isolation or MRSA or P. aeruginosa or a recent hospitalization with receipt of IV antibiotics within the past 90 days. Patients with chronic heart, lung, liver, or kidney diseases, as well as those with diabetes, cancer, asplenia, or alcoholism (collectively termed comorbidities) also have unique treatment recommendations.

For outpatients with no comorbidities or risk factors for MRSA or P. aeruginosa, amoxicillin, doxycycline, or a macrolide are all appropriate choices, assuming local pneumococcal resistance to macrolides is less than 25%. Patients with comorbidities should receive either a respiratory fluoroquinolone alone or combination therapy with a macrolide or doxycycline with a beta-lactam (specifically amoxicillin/clavulanate or a cephalosporin). The guidelines also support the use of alternating antibiotic classes in patients with recent antibiotic exposures.

Combination of beta-lactam plus a macrolide or respiratory fluoroquinolone monotherapy remains the cornerstone of inpatient, nonsevere CAP empiric treatment. Specific beta-lactams mentioned by the guidelines are ampicillin/sulbactam, cefotaxime, ceftriaxone, or ceftaroline. Beta-lactam monotherapy was initially considered, but ultimately not included as a guideline recommendation based on the available evidence. Coverage for MRSA or P. aeruginosa should be added if the patient has had a prior respiratory isolation of either organism. For patients with recent hospitalizations and IV antibiotics, or those with risk factors for either MRSA or P. aeruginosa, cultures should be obtained, but antibiotics that cover these organisms should be reserved for only positive cultures.

The guidelines do make 1 exception: if a hospital uses nasal PCR to screen for MRSA and the PCR is positive, empiric MRSA antibiotics should be added, but cultures should be obtained and therapy de-escalated as appropriate once the results of the gram stain and culture are available.

Severe inpatient CAP treatment also remains relatively unchanged. Combination therapy with a beta-lactam plus either a macrolide or a respiratory fluoroquinolone is recommended for empiric treatment. Empiric coverage versus MRSA or P. aeruginosa should be added for all patients with prior isolation of the organism. Unlike in nonsevere CAP, empiric therapy is also recommended in those patients with recent hospitalizations with IV antibiotics and/or risk factors for the organisms.

Corticosteroids, an often debated option for pneumonia, is only recommended in patients who have refractory septic shock. This may come as a change of practice for many, but the lack of supportive evidence is cited by the authors as rationale for not supporting their routine use in pneumonia.

Finally, the question of duration of therapy has been on the minds of many since the nosocomial guidelines recommended a more explicit duration. However, for CAP, the authors of the guidelines remain less committed. They still recommend that therapy be continued for at least 5 days, but that clinical indicators of stability, such as vital signs, ability to eat, and normal mental status should dictate duration beyond that time. The guidelines do note that failure to respond by day 5 is associated with worse outcomes, and it may be prudent to reassess therapy if the patient is not improving. However, for patients receiving coverage for MRSA or P. aeruginosa, the authors recommend a 7-day duration of therapy. Therefore, it seems realistic to anticipate that most patients will be treated for CAP somewhere between 7-10 days.

Overall, the 12-year span in CAP guidelines has resulted in relatively minimal changes to care. Although steroids are not recommended, few changes to antibiotic recommendations were made, with the exception of providing detail on which patients should be empirically covered for MRSA and P. aeruginosa. However, with pneumonia season approaching, it is prudent for the pharmacist to be up-to-date with the most evidence-based treatment recommendations for the most common pulmonary infection.


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 Car Med.2019;200:e45-e67