DALLAS — Selection of an antibiotic for the treatment of community-acquired pneumonia should be based on the severity of the illness, coverage of common pathogens, and presence of factors that increase the risk for aspiration and/or infection with antibiotic-resistant organisms, Dr. Horace M. DeLisser said at the annual meeting of the National Medical Association.
Physicians shouldn't wait for culture results before treating. Instead, they should rely on the history to identify risk factors that will require modifying the treatment plan, said Dr. DeLisser of the pulmonary, allergy, and critical care division of the University of Pennsylvania, Philadelphia.
To determine whether the patient should be treated on an inpatient or outpatient basis, physicians can use the pneumonia severity index, a widely utilized and rigorously studied prediction rule, he said.
The index is based on 20 parameters that are commonly available at presentation, including demographic information, exam findings, and lab and imaging results. Each parameter is assigned a specific point value that allows physicians to stratify patients into five risk classes.
Classes 1–3 are low risk, class 4 is moderate risk, and class 5 is high risk. Generally, patients in risk classes 1 and 2 are treated on an outpatient basis, those in risk classes 4 and 5 are treated as inpatients, and those in class 3 may be treated as outpatients or admitted briefly, Dr. DeLisser said. “Your clinical judgment should always be used, particularly if there are other psychosocial or emotion factors,” he said.
Dr. DeLisser advised physicians not to wait for the culture to come back. Between 40% and 60% of patients will have no pathogens identified, and for inpatients, early administration of antibiotics decreases mortality, he said. Instead, physicians should take into account the modified risk factors for infections, such as residence in a nursing home, underlying disease, and recent antibiotic therapy.
Several organizations in the United States, Europe, and Asia have developed guidelines for the treatment of community-acquired pneumonia. The following treatment recommendations are based on guidelines developed by the American Thoracic Society (www.thoracic.org/sections/publications/statements/pages/mtpi/commacq1-25.html
▸ In otherwise healthy adults who do not have modifying risk factors, use an advanced-generation macrolide, such as azithromycin or clarithromycin. Another option for this group is treatment with doxycycline.
▸ For outpatients with comorbid disease or modifying risk factors, use a respiratory fluoroquinolone alone, or β-lactam plus an advanced-generation macrolide.
▸ For otherwise healthy inpatients who are not in the ICU, use an intravenous respiratory fluoroquinolone alone or intravenous azithromycin alone.
▸ For inpatients with comorbid disease or modifying risk factors, use intravenous respiratory fluoroquinolones alone or a combination of intravenous azithromycin plus intravenous β-lactam.
▸ Patients in the ICU who do not have risk factors for Pseudomonas aeruginosa infection can be treated with intravenous β-lactam plus either intravenous azithromycin or intravenous respiratory fluoroquinolone.
▸ Those patients at risk for P. aeruginosa infection can be treated with intravenous antipseudomonal β-lactam plus intravenous antipseudomonal fluoroquinolone. Another option is treatment with intravenous antipseudomonal β-lactam plus intravenous aminoglycoside plus either intravenous azithromycin or intravenous nonpseudomonal fluoroquinolone.
Most patients will become clinically stable within 3–7 days. Treatment is recommended for a minimum of 5–7 days and for at least 48 hours after reaching clinical stability, Dr. DeLisser said. Longer treatment—between 10 and 14 days—may be required for patients with infections caused by Staphylococcus aureus, P. aeruginosa, or Legionella species.
Patients can be discharged once their vital signs have been stable for a 24-hour period, they are able to take oral antibiotics, they can maintain adequate nutrition and hydration on their own, their mental status is back to baseline, and they have no other active clinical or psychosocial issues.
If the pneumonia does not resolve, consider microbial resistance to the initial antimicrobial regimen, suppurative complications like an abscess or empyema, or subsequent development of nosocomial pneumonia, Dr. DeLisser said.