Epidemiology of clinically diagnosed community-acquired pneumonia in the primary care setting: results from the 1999-2000 respiratory surveillance program.

To evaluate the prevalence of typical pathogens, level of resistance, and risk factors associated with community-acquired pneumonia (CAP) in the outpatient primary care setting and define current antibiotic treatment for office-based CAP, the Respiratory Surveillance Program (RESP) recruited 1,200 primary care clinics during the 1999-2000 respiratory infection season. Participating community-based physicians submitted sputum samples from patients presenting with a community-acquired respiratory infection including community-acquired pneumonia (CAP). All patients were aged > or =18 years. Patient demographics and risk factors were collected. Physicians express-mailed the specimens to a central laboratory for identification and susceptibility testing. All isolates were tested against a select panel of antimicrobial agents that are used to treat CAP. Patients with CAP were diagnosed by the treating physicians. Chest radiographs were not required as part of the study. A total of 610 specimens were submitted from patients with CAP. A smoking history or reported history of chronic obstructive pulmonary disease were present in >50% of those diagnosed with CAP. The most common pathogens were, in order of prevalence, Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis. During the study period, a variety of antibiotics were prescribed for the treatment of outpatient CAP. The top 3 prescribed antibiotics include levofloxacin (23%), clarithromycin (19%), and azithromycin (10%). Gatifloxacin, which was approved in December 1999 and therefore available for only part of the study, accounted for 4% of the prescriptions. Of S pneumoniae isolates, 8% demonstrated high-level resistance to penicillin (> or =2 microg/mL) and 33% were found resistant to macrolides and trimethoprim/sulfamethoxazole. All S pneumoniae isolates were sensitive to gatifloxacin, vancomycin, and levofloxacin. Other less common organisms isolated were staphylococci, streptococci, Enterobacteriaceae, Pseudomonas spp, and Acinetobacter spp. The choice of antibiotic to treat outpatient CAP varies from practice to practice and does not appear to be influenced by the patient's age, the patient's history of smoking, or comorbidity.