The Centers for Disease Control and Prevention (CDC) assembled a panel of national health experts, including physicians with expertise in internal, family, emergency and infectious diseases medicine, to develop evidencebased guidelines for evaluating and treating adults with acute respiratory illnesses. Joining the CDC were the American Academy of Family Physicians, the American College of Physicians-American Society of Internal Medicine and the Infectious Diseases Society of America. The complete treatment guidelines were published in the March 20, 2001 issue of Annals of Internal Medicine, and they can be viewed online athttp://annals.org.

Excessive use of antibiotics in ambulatory practice has contributed to the emergence and spread of antibioticresistant bacteria in the community. The majority of antibiotics are prescribed for acute sinusitis, acute pharyngitis, acute bronchitis and nonspecific upper respiratory tract infections (including the common cold). A large proportion of these prescriptions will provide no benefit to patients. The goal of the principles is to provide clinicians with practical strategies for limiting antibiotic use to the patients who are most likely to benefit from it. These principles should be used along with effective patient educational campaigns and enhancements to the health care delivery system that facilitate nonantibiotic treatment of the conditions in question.

Penicillin resistance to Streptococcus pneumoniae has increased in an epidemic manner in the past 10 years. Resistance to macrolides, doxycycline, trimethoprimsulfamethoxazole, and second- and third-generation cephalosporins has also increased. Special attention to antibiotic-resistant profiles of S. pneumoniae is warranted because this pathogen is the leading cause of community acquired bacterial pneumonia, bacterial meningitis, bacterial sinusitis and otitis media in the United States.

The major risk factors for carriage of and infection with antibiotic-resistant S. pneumoniae are geographic location, recent exposure to antibiotics, especially for a prolonged period, and exposure to young children. The risk of being an antibiotic-resistant S. pneumoniae carrier is two to nine times greater in persons who have recently used antibiotics. In adults hospitalized with community-acquired pneumonia, mortality was significantly associated with high-level antibiotic-resistant S. pneumoniae.

Intervention strategies aimed at reducing community use of antibiotics should address the management of acute respiratory infection through physician and patient education at the household and office levels. Acute respiratory infections are the most frequent reason for seeking medical attention in the United States, and they are associated with up to 75 percent of the total antibiotic prescriptions written each year. Antibiotic treatment of a cold, an upper respiratory tract infection or acute bronchitis is usually inappropriate because the majority of these syndromes have a nonbacterial cause. Using antibiotics for treating sinusitis and pharyngitis is justified if it is limited to appropriate subsets of patients.

The panel also examined the possible benefits and harms of following these prescribing principles.

Potential Benefits of Indiscriminate Antibiotic Prescription. Some physicians may prescribe antibiotics because they believe that they might help a small fraction of patients. There will always be specific outcomes that cannot be measured. Indiscriminate use may also prevent complications of other undiagnosed bacterial infections or remote cases of a bad outcome.

Potential Harms of Indiscriminate Antibiotic Prescription. For patients, risks include allergic reactions, adverse reactions, drug-drug interactions, and the increased likelihood that a pneumococcal infection in the following months will be caused by an antibiotic-resistant strain. This could also serve to medicalize viral illnesses, taking away the ability of individuals to care for self-limited illnesses, leading to unnecessary office visits and prescriptions.

Potential Benefits of Limiting Indiscriminate Antibiotic Prescriptions. Besides decreasing the risks to patients and affecting health care costs, the desired effect would be reducing, and possibly reversing, the increase in antibiotic-resistantS. pneumoniae.

Potential Harms of Limiting Antibiotic Prescriptions. The perception is that not prescribing antibiotics will lead to patient dissatisfaction with care and more return visits. The decision to prescribe an antibiotic for acute respiratory infection is a result of complex interactions among the patient, physician and the health care system. Patient expectations and demands for antibiotics have been singled out in some studies as having a strong association with excess antibiotic use. Also, other studies have found that as patient volume increased, the limited time physicians have to discuss nonantibiotic alternative treatments has also been a problem. Rates of antibiotic prescriptions for upper respiratory infection increases as patient volume increases.

Each article in the CDC series focuses on the major decisions or issues that physicians face during evaluation of patients with symptoms of acute respiratory illness. These decisions center on establishing a diagnosis, estimating the likelihood of a bacterial cause and determining if antibiotic therapy is needed. For each condition, an evidence model was developed to frame specific questions to be addressed. To determine which, if any, patients with bronchitis, sinusitis, pharyngitis or nonspecific upper respiratory tract infection are likely to benefit from antibiotic treatment, depends on accurate diagnosis and assessment of the likelihood of a bacterial cause. The panel avoided detailed discussions of specific antibiotic treatments because the information is available in other publications and local resistance patterns continue to evolve.

The principles are intended to be recommendations based on an evidence-based analysis and interpretation of current scientific literature. The panel's conclusions do not necessarily reflect those of the original studies. These principles apply to immunocompetent adults who do not have significant comorbid conditions. Physicians are advised to use caution in the elderly, because persons older than 65 years were often underrepresented in or excluded from treatment trials.