Pulmonologists and infectious disease experts join forces to produce new recommendations for community-acquired pneumonia.

Both the Infectious Diseases Society of America and the American Thoracic Society have previously issued guidelines on the management of community-acquired pneumonia (CAP), most recently in 2003 and 2001, respectively, but a 2007 version represents their first joint effort in this sphere (Clin Infect Dis. 2007;44 [Suppl 2]:S27-S72). The joint committee was formed in response to confusion regarding differences between previous guidelines.

While recommendations in such fundamental areas as antibiotic therapy remain substantially unchanged from earlier guidelines, there have been noteworthy modifications for both assessment and treatment of this common disease, according to Lionel A. Mandell, MD, professor of medicine at McMaster University, Hamilton, Ontario, and cochair of the committee that produced the Guidelines.

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CAP is largely a primary-care problem, Dr. Mandell notes. “It may vary from place to place, but most, if not all, primary-care clinicians are involved in [its] outpatient management, which makes up 80% of cases, and they may admit and take care of patients in some community hospitals as well.”

Treatment setting

Site-of-care decisions—outpatient or hospital —depend on initial assessment. The new Guidelines recommend either of two formal systems to score illness severity—the pneumonia severity index or CURB-65 (see “Assessing pneumonia severity”)—augmented, as always, by clinical judgment and evaluation of such factors as available support and the patient’s ability to take oral medication.

“If you don’t have a lot of time or a lot of backup, CURB-65 is fine,” Dr. Mandell says.

Once pneumonia is diagnosed (based on clinical features and an infiltrate demonstrable on chest imaging), the question arises whether to test for etiology: Generally, testing is recommended when there is good reason to suspect the results will change how you manage the patient. Defining this contingency is addressed at greater length in these guidelines than in earlier versions.

The use of such tests (e.g., blood culture, sputum stain and culture) for outpatients remains “optional” and is usually not necessary—exceptions may be made to distinguish, via rapid point-of-care diagnostic tests, among subtypes of influenza or between influenza and respiratory syncytial virus, or when you suspect severe acute respiratory syndrome (SARS), avian influenza, or Legionella infection.

Criteria have narrowed for hospitalized patients. Where tests of etiology were previously suggested as part of the standard workup, the new Guidelines recommend them only for pneumonia in the context of specified factors, including recent alcohol use, recent travel, severe liver or obstructive/structural lung disease, leukopenia, cavitary infiltrates, and pleural effusion. ICU admissions and patients who have severe disease or who have failed outpatient antibiotic therapy should be tested as well.

Antibiotic treatment

One antibiotic has been added to the recommendations: ertapenem, a carbapenem now listed among alternatives for hospitalized patients at high risk for infection with a gram-negative pathogen other than Pseudomonas. Another agent, telithromycin, the first of a new class of ketolide antibiotics, has been approved for Streptococcus pneumoniae resistant to agents commonly used for CAP. But the Guidelines committee made no recommendation for this drug, pending FDA investigation of postmarketing reports of hepatotoxicity.

Generally, the Guidelines characterize regimens by class, rather than individual agent (see algorithm). For most outpatients, a macrolide (azithromycin, clarithromycin, or erythromycin) is strongly recommended, while doxycycline, an alternative, is supported by weaker evidence. Comorbidities, such as chronic lung, heart, liver, or renal disease; diabetes; or malignancy, or the presence of immunosuppressing conditions or drugs indicate the need for a respiratory fluoroquinolone (moxifloxacin, gemifloxacin, or levofloxacin), or a beta-lactam plus a macrolide or doxycycline.

The same regimens should be considered when the risk of drug-resistant S. pneumoniae is high (choose an alternative to the macrolide if the community prevalence of macrolide-resistant S. pneumoniae is >25%). For patients ill enough to be hospitalized, the latter recommendations also apply: a fluoroquinolone or beta-lactam plus a macrolide. A macrolide alone can no longer be routinely recommended for inpatients, even those with less severe pneumonia, in light of increasing rates of pathogen resistance to that class of drugs.

Recent increases in prevalence have made community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) a concern, Dr. Mandell points out. “Most of these patients are quite sick—if they’re well enough to be treated outside the hospital, it probably isn’t MRSA. If a patient is hospitalized and you know there’s a lot of CA-MRSA out there, you may want to add coverage for MRSA” (the Guidelines recommend vancomycin or linezolid).

Other treatment parameters

The new Guidelines recommend that treatment for uncomplicated pneumonia be maintained for a minimum of five days, while noting that 7-10 days had been customary. “There are good data now that for average cases of pneumonia, five days is sufficient,” Dr. Mandell says. This assumes that fever has been absent for 48-72 hours, and there is no more than one other sign of clinical instability (e.g., elevated heart or respiratory rate; systolic BP ≤90 mm Hg; diminished arterial oxygen saturation).

The treatment period should also be extended if CAP was complicated by meningitis or other extrapulmonary infection, or if the first antibiotic used was not active against a subsequently identified pathogen.

The timing of treatment initiation is more loosely proscribed than in earlier guidelines, which had defined as acceptable a window of four hours after presentation. Rather, the committee recommends that antibiotic administration begin “as soon as possible after the diagnosis is considered likely.” “It was felt that clinicians were being penalized if treatment wasn’t started in four hours, and there were problems with internal consistency of the data” supporting a specified time window, Dr. Mandell notes.

The Infectious Diseases Society of America/American Thoracic Society Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults appeared in Clinical Infectious Diseases (2007;44 [Suppl 2]:S27-S72). They are available at: www.journals.uchicago.edu/CID/journal/issues/v44nS2/41620/41620.html (accessed September 20, 2007).

Mr. Sherman is a medical writer in New York City.