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Atypical pathogen treatment vital in hospitalized CAP patients

May 15, 2007

Hospitalized patients with community-acquired pneumonia (CAP) who received treatment regimens against atypical disease-causing pathogens reached clinical stability quicker, had fewer days of hospitalization, and had lower mortality rates as a result of their disease, according to a large new study.

The research results appear in the second issue for May 2007 of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.

Forest W. Arnold, D.O., of the Division of Infectious Diseases at the University of Louisville, and 13 associates found a 22 percent global incidence of atypical pneumonia infections in 4,337 patients. Atypical pneumonias are those diseases caused by organisms other than the so-called "typical" bacteria, viruses or fungi.

Atypical treatment was defined as the use of any antibiotic regimen that contained a macrolide, fluoroquinolone or tetracycline (all broad-spectrum antibiotics).

After dividing the world into four areas and using 2,208 patients listed in the Community-Acquired Pneumonia Organization (CAPO) database, the number of patients who received an atypical treatment regimen in Region I (North America) was 91 percent, with 74 percent in Region II (Europe), 53 percent in Region III (Latin America), and 10 percent in Region IV (Africa and Asia).

According to the authors, hospitalized patients treated with antimicrobials against atypical pathogens reduced the time to clinical stability from 3.7 days to 3.2; their hospital stay from 7.1 days to 6.1; total mortality from 11.1 percent to 7 percent; and CAP-related mortality from 6.4 percent to 3.8.

"This study indicates that, although the incidence of atypical pathogens is relatively similar in all regions of the world, there are significant differences in the proportion of patients who are treated with an empiric regimen that cover for atypical pathogens," said Dr. Arnold.

Guidelines from the U.S., Canada, Germany, Japan and parts of Latin America recommend using a regimen that covers atypical pathogens in all hospitalized patients with community-acquired pneumonia.

According to the American Thoracic Society guidelines for CAP, clinical stability is defined by the following factors: improved clinical signs (improved cough and shortness of breath), lack of fever for at least eight hours, a decrease by at least 10 percent from the previous day in the number of leukocytes (white blood cells), and the ability to take oral nourishment.

The authors point out that estimates show mortality may not be directly related to the pulmonary infection in up to half the hospitalized patients with CAP.

"Also, in ambulatory patients with CAP, the beneficial effect of antibiotics using atypical coverage is more difficult to recognize because the time to clinical stability in this population is not measured and mortality is a very rare outcome," said Dr. Arnold.

American Thoracic Society