Commentary on the 1993 American Thoracic Society guidelines for the treatment of community-acquired pneumonia.

Early treatment of community-acquired pneumonia (CAP) is associated with improved outcome. Since extensive diagnostic testing identifies an etiologic agent in only half of the cases and usually requires several hours or even days for results, CAP is most often initially treated empirically. In 1993, the American Thoracic Society (ATS) established guidelines to assist primary care physicians in antibiotic selection for the initial empiric treatment of CAP in immunocompetent adults. Since publication of the guidelines, the incidence of certain bacteria has been redefined, antimicrobial resistance patterns have changed, risk factors for stratifying need for hospitalization have been further defined, and newer antibiotics have been introduced. These changes necessitate a reevaluation of the 1993 ATS guidelines. This article proposes a modification of the ATS guidelines. This modification continues to classify patients into groups, based on specific risk factors, to which a limited number of likely pathogens are identified and for which antibiotic treatment regimens are developed. The modification differs from the original ATS guidelines because of the changes in risk factors. Patient groups are still broadly divided into outpatient and inpatient care, but earlier risk factors of age and coexisting illness have been refined. Risk factors suggested herein as considerations to guide treatment include the presence of cardiopulmonary disease, history of smoking, severity of illness, risk of drug-resistant Streptococcus pneumoniae and Pseudomonas aeruginosa, and need for ICU admission.