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"Community-Acquired Pneumonia in Adults: Guidelines for Management"

update in progress
Published: Clinical Infectious Diseases ; 2007 ; 44 : S27 -S72


Improving the care of adult patients with community-acquired pneumonia (CAP) has been the focus of many different organizations, and several have developed guidelines for management of CAP. Two of the most widely referenced are those of the Infectious Diseases Society of America (IDSA) and the American Thoracic Society (ATS). In response to confusion regarding differences between their respective guidelines, the IDSA and the ATS convened a joint committee to develop a unified CAP guideline document. 

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*Projected Publication, Summer 2018


1. Locally adapted guidelines should be implemented to improve process of care variables and relevant clinical outcomes. (Strong recommendation; level I evidence.)

Enthusiasm for developing these guidelines derives, in large part, from evidence that previous CAP guidelines have led to improvement in clinically relevant outcomes. Consistently beneficial effects in clinically relevant parameters (listed in table 3) followed the introduction of a comprehensive protocol (including a combination of components from table 2) that increased compliance with published guidelines. The first recommendation, therefore, is that CAP management guidelines be locally adapted and implemented.

Documented benefits.

2. CAP guidelines should address a comprehensive set of elements in the process of care rather than a single element in isolation. (Strong recommendation; level III evidence.)

3. Development of local CAP guidelines should be directed toward improvement in specific and clinically relevant outcomes. (Moderate recommendation; level III evidence.)

Site-of-Care Decisions

Almost all of the major decisions regarding management of CAP, including diagnostic and treatment issues, revolve around the initial assessment of severity. Site-of-care decisions (e.g., hospital vs. outpatient, intensive care unit [ICU] vs. general ward) are important areas for improvement in CAP management.

Hospital admission decision

4. Severity-of-illness scores, such as the CURB-65 criteria (confusion, uremia, respiratory rate, low blood pressure, age 65 years or greater), or prognostic models, such as the Pneumonia Severity Index (PSI), can be used to identify patients with CAP who may be candidates for outpatient treatment. (Strong recommendation; level I evidence.)

5. Objective criteria or scores should always be supplemented with physician determination of subjective factors, including the ability to safely and reliably take oral medication and the availability of outpatient support resources. (Strong recommendation; level II evidence.)

6. For patients with CURB-65 scores ⩾2, more-intensive treatment—that is, hospitalization or, where appropriate and available, intensive in-home health care services—is usually warranted. (Moderate recommendation; level III evidence.)

Physicians often admit patients to the hospital who could be well managed as outpatients and who would generally prefer to be treated as outpatients. Objective scores, such as the CURB-65 score or the PSI, can assist in identifying patients who may be appropriate for outpatient care, but the use of such scores must be tempered by the physician's determination of additional critical factors, including the ability to safely and reliably take oral medication and the availability of outpatient support resources.

ICU admission decision.

7. Direct admission to an ICU is required for patients with septic shock requiring vasopressors or with acute respiratory failure requiring intubation and mechanical ventilation. (Strong recommendation; level II evidence.)

8. Direct admission to an ICU or high-level monitoring unit is recommended for patients with 3 of the minor criteria for severe CAP listed in table 4. (Moderate recommendation; level II evidence.)

In some studies, a significant percentage of patients with CAP are transferred to the ICU in the first 24–48 h after hospitalization. Mortality and morbidity among these patients appears to be greater than those among patients admitted directly to the ICU. Conversely, ICU resources are often overstretched in many institutions, and the admission of patients with CAP who would not directly benefit from ICU care is also problematic. Unfortunately, none of the published criteria for severe CAP adequately distinguishes these patients from those for whom ICU admission is necessary. In the present set of guidelines, a new set of criteria has been developed on the basis of data on individual risks, although the previous ATS criteria format is retained. In addition to the 2 major criteria (need for mechanical ventilation and septic shock), an expanded set of minor criteria (respiratory rate, >30 breaths/min; arterial oxygen pressure/fraction of inspired oxygen (PaO2/FiO2) ratio, <250; multilobar infiltrates; confusion; blood urea nitrogen level, >20 mg/dL; leukopenia resulting from infection; thrombocytopenia; hypothermia; or hypotension requiring aggressive fluid resuscitation) is proposed (table 4). The presence of at least 3 of these criteria suggests the need for ICU care but will require prospective validation.

Diagnostic Testing

9. In addition to a constellation of suggestive clinical features, a demonstrable infiltrate by chest radiograph or other imaging technique, with or without supporting microbiological data, is required for the diagnosis of pneumonia. (Moderate recommendation; level III evidence.)

Recommended diagnostic tests for etiology

10. Patients with CAP should be investigated for specific pathogens that would significantly alter standard (empirical) management decisions, when the presence of such pathogens is suspected on the basis of clinical and epidemiologic clues. (Strong recommendation; level II evidence.)

Recommendations for diagnostic testing remain controversial. The overall low yield and infrequent positive impact on clinical care argue against the routine use of common tests, such as blood and sputum cultures. Conversely, these cultures may have a major impact on the care of an individual patient and are important for epidemiologic reasons, including the antibiotic susceptibility patterns used to develop treatment guidelines. A list of clinical indications for more extensive diagnostic testing (table 5) was, therefore, developed, primarily on the basis of 2 criteria: (1) when the result is likely to change individual antibiotic management and (2) when the test is likely to have the highest yield.

11. Routine diagnostic tests to identify an etiologic diagnosis are optional for outpatients with CAP. (Moderate recommendation; level III evidence.)

12. Pretreatment blood samples for culture and an expectorated sputum sample for stain and culture (in patients with a productive cough) should be obtained from hospitalized patients with the clinical indications listed in table 5 but are optional for patients without these conditions. (Moderate recommendation; level I evidence.)

13. Pretreatment Gram stain and culture of expectorated sputum should be performed only if a good-quality specimen can be obtained and quality performance measures for collection, transport, and processing of samples can be met. (Moderate recommendation; level II evidence.)

14. Patients with severe CAP, as defined above, should at least have blood samples drawn for culture, urinary antigen tests for Legionella pneumophila and Streptococcus pneumoniae performed, and expectorated sputum samples collected for culture. For intubated patients, an endotracheal aspirate sample should be obtained. (Moderate recommendation; level II evidence.)

The most clear-cut indication for extensive diagnostic testing is in the critically ill CAP patient. Such patients should at least have blood drawn for culture and an endotracheal aspirate obtained if they are intubated; consideration should be given to more extensive testing, including urinary antigen tests for L. pneumophila and S. pneumoniae and Gram stain and culture of expectorated sputum in nonintubated patients. For inpatients without the clinical indications listed in table 5, diagnostic testing is optional (but should not be considered wrong).

Antibiotic Treatment

Empirical antimicrobial therapy.Empirical antibiotic recommendations (table 7) have not changed significantly from those in previous guidelines. Increasing evidence has strengthened the recommendation for combination empirical therapy for severe CAP. Only 1 recently released antibiotic has been added to the recommendations: ertapenem, as an acceptable β-lactam alternative for hospitalized patients with risk factors for infection with gram-negative pathogens other than Pseudomonas aeruginosa. At present, the committee is awaiting further evaluation of the safety of telithromycin by the US Food and Drug Administration before making its final recommendation regarding this drug. Recommendations are generally for a class of antibiotics rather than for a specific drug, unless outcome data clearly favor one drug. Because overall efficacy remains good for many classes of agents, the more potent drugs are given preference because of their benefit in decreasing the risk of selection for antibiotic resistance.

Outpatient treatment

15. Previously healthy and no risk factors for drug-resistant S. pneumoniae (DRSP) infection:

A macrolide (azithromycin, clarithromycin, or erythromycin) (strong recommendation; level I evidence)

Doxycycline (weak recommendation; level III evidence)

16. Presence of comorbidities, such as chronic heart, lung, liver, or renal disease; diabetes mellitus; alcoholism; malignancies; asplenia; immunosuppressing conditions or use of immunosuppressing drugs; use of antimicrobials within the previous 3 months (in which case an alternative from a different class should be selected); or other risks for DRSP infection:

A. A respiratory fluoroquinolone (moxifloxacin, gemifloxacin, or levofloxacin [750 mg]) (strong recommendation; level I evidence) B. A. β-lactam plus a macrolide (strong recommendation; level I evidence) (High-dose amoxicillin [e.g., 1 g 3 times daily] or amoxicillin-clavulanate [2 g 2 times daily] is preferred; alternatives include ceftriaxone, cefpodoxime, and cefuroxime [500 mg 2 times daily]; doxycycline [level II evidence] is an alternative to the macrolide.)

17. In regions with a high rate (>25%) of infection with high-level (MIC, ⩾16 µg/mL) macrolide-resistant S. pneumoniae, consider the use of alternative agents listed above in recommendation 16 for any patient, including those without comorbidities. (Moderate recommendation; level III evidence.)

Inpatient, non-ICU treatment

18. A respiratory fluoroquinolone (strong recommendation; level I evidence)

19. β-lactam plus a macrolide (strong recommendation; level I evidence) (Preferred β-lactam agents include cefotaxime, ceftriaxone, and ampicillin; ertapenem for selected patients; with doxycycline [level III evidence] as an alternative to the macrolide. A respiratory fluoroquinolone should be used for penicillin-allergic patients.)

Increasing resistance rates have suggested that empirical therapy with a macrolide alone can be used only for the treatment of carefully selected hospitalized patients with nonsevere disease and without risk factors for infection with drug-resistant pathogens. However, such monotherapy cannot be routinely recommended. Inpatient, ICU treatment

20. β-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) plus either azithromycin (level II evidence) or a fluoroquinolone (level I evidence) (strong recommendation) (For penicillin-allergic patients, a respiratory fluoroquinolone and aztreonam are recommended.)

21. For Pseudomonas infection, use an antipneumococcal, antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) plus either ciprofloxacin or levofloxacin (750-mg dose) or the above β-lactam plus an aminoglycoside and azithromycin or the above β-lactam plus an aminoglycoside and an antipneumococcal fluoroquinolone (for penicillin-allergic patients, substitute aztreonam for the above β-lactam).

(Moderate recommendation; level III evidence.)

22. For community-acquired methicillin-resistant Staphylococcus aureus infection, add vancomycin or linezolid. (Moderate recommendation; level III evidence.)

Infections with the overwhelming majority of CAP pathogens will be adequately treated by use of the recommended empirical regimens. The emergence of methicillin-resistant S. aureus as a CAP pathogen and the small but significant incidence of CAP due to P. aeruginosa are the exceptions. These pathogens occur in specific epidemiologic patterns and/or with certain clinical presentations, for which empirical antibiotic coverage may be warranted. However, diagnostic tests are likely to be of high yield for these pathogens, allowing early discontinuation of empirical treatment if results are negative. The risk factors are included in the table 5 recommendations for indications for increased diagnostic testing.Pathogens suspected on the basis of epidemiologic considerations.

Risk factors for other uncommon etiologies of CAP are listed in table 8, and recommendations for treatment are included in table 9.

Pathogen-directed therapy.

23. Once the etiology of CAP has been identified on the basis of reliable microbiological methods, antimicrobial therapy should be directed at that pathogen. (Moderate recommendation; level III evidence.)

24. Early treatment (within 48 h of the onset of symptoms) with oseltamivir or zanamivir is recommended for influenza A. (Strong recommendation; level I evidence.)

25. Use of oseltamivir and zanamivir is not recommended for patients with uncomplicated influenza with symptoms for >48 h (level I evidence), but these drugs may be used to reduce viral shedding in hospitalized patients or for influenza pneumonia. (Moderate recommendation; level III evidence.)

Pandemic influenza

26. Patients with an illness compatible with influenza and with known exposure to poultry in areas with previous H5N1 infection should be tested for H5N1 infection. (Moderate recommendation; level III evidence.)

27. In patients with suspected H5N1 infection, droplet precautions and careful routine infection control measures should be used until an H5N1 infection is ruled out. (Moderate recommendation; level III evidence.)

28. Patients with suspected H5N1 infection should be treated with oseltamivir (level II evidence) and antibacterial agents targeting S. pneumoniae and S. aureus, the most common causes of secondary bacterial pneumonia in patients with influenza (level III evidence). (Moderate recommendation.)

Time to first antibiotic dose.

29. For patients admitted through the emergency department (ED), the first antibiotic dose should be administered while still in the ED. (Moderate recommendation; level III evidence.)

Rather than designating a specific window in which to initiate treatment, the committee felt that hospitalized patients with CAP should receive the first antibiotic dose in the ED. Switch from intravenous to oral therapy.

30. Patients should be switched from intravenous to oral therapy when they are hemodynamically stable and improving clinically, are able to ingest medications, and have a normally functioning gastrointestinal tract. (Strong recommendation; level II evidence.)

31. Patients should be discharged as soon as they are clinically stable, have no other active medical problems, and have a safe environment for continued care. Inpatient observation while receiving oral therapy is not necessary. (Moderate recommendation; level II evidence.)

Duration of antibiotic therapy.

32. Patients with CAP should be treated for a minimum of 5 days (level I evidence), should be afebrile for 48–72 h, and should have no more than 1 CAP-associated sign of clinical instability (table 10) before discontinuation of therapy (level II evidence). (Moderate recommendation.)

33. A longer duration of therapy may be needed if initial therapy was not active against the identified pathogen or if it was complicated by extrapulmonary infection, such as meningitis or endocarditis. (Weak recommendation; level III evidence.)

Other Treatment Considerations

34. Patients with CAP who have persistent septic shock despite adequate fluid resuscitation should be considered for treatment with drotrecogin alfa activated within 24 h of admission. (Weak recommendation; level II evidence.)

35. Hypotensive, fluid-resuscitated patients with severe CAP should be screened for occult adrenal insufficiency. (Moderate recommendation; level II evidence.)

36. Patients with hypoxemia or respiratory distress should receive a cautious trial of noninvasive ventilation unless they require immediate intubation because of severe hypoxemia (PaO2/FiO2 ratio, <150) and bilateral alveolar infiltrates. (Moderate recommendation; level I evidence.)

37. Low-tidal-volume ventilation (6 cm3/kg of ideal body weight) should be used for patients undergoing ventilation who have diffuse bilateral pneumonia or acute respiratory distress syndrome. (Strong recommendation; level I evidence.)

Management of Nonresponding Pneumonia Definitions and classification.

38. The use of a systematic classification of possible causes of failure to respond, based on time of onset and type of failure (table 11), is recommended. (Moderate recommendation; level II evidence.)

As many as 15% of patients with CAP may not respond appropriately to initial antibiotic therapy. A systematic approach to these patients (table 11) will help to determine the cause. Because determination of the cause of failure is more accurate if the original microbiological etiology is known, risk factors for nonresponse or deterioration (table 12) figure prominently in the list of situations in which more aggressive and/or extensive initial diagnostic testing is warranted (table 5).

Prevention (see table 13)

39. All persons ⩾50 years of age, others at risk for influenza complications, household contacts of high-risk persons, and health care workers should receive inactivated influenza vaccine as recommended by the Advisory Committee on Immunization Practices, Centers for Disease Control and Prevention. (Strong recommendation; level I evidence.)

40. The intranasally administered live attenuated vaccine is an alternative vaccine formulation for some persons 5–49 years of age without chronic underlying diseases, including immunodeficiency, asthma, or chronic medical conditions. (Strong recommendation; level I evidence.)

41. Health care workers in inpatient and outpatient settings and long-term care facilities should receive annual influenza immunization. (Strong recommendation; level I evidence.)

42. Pneumococcal polysaccharide vaccine is recommended for persons ⩾65 years of age and for those with selected high-risk concurrent diseases, according to current Advisory Committee on Immunization Practices guidelines. (Strong recommendation; level II evidence.)

43. Vaccination status should be assessed at the time of hospital admission for all patients, especially those with medical illnesses. (Moderate recommendation; level III evidence.)

44. Vaccination may be performed either at hospital discharge or during outpatient treatment. (Moderate recommendation; level III evidence.)

45. Influenza vaccine should be offered to persons at hospital discharge or during outpatient treatment during the fall and winter. (Strong recommendation; level III evidence.)

46. Smoking cessation should be a goal for persons hospitalized with CAP who smoke. (Moderate recommendation; level III evidence.)

47. Smokers who will not quit should also be vaccinated for both pneumococcus and influenza. (Weak recommendation; level III evidence.)

48. Cases of pneumonia that are of public health concern should be reported immediately to the state or local health department. (Strong recommendation; level III evidence.)

49. Respiratory hygiene measures, including the use of hand hygiene and masks or tissues for patients with cough, should be used in outpatient settings and EDs as a means to reduce the spread of respiratory infections. (Strong recommendation; level III evidence.)

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