Community-Acquired Pneumonia Guidelines
Community-Acquired Pneumonia Guidelines
In US CAP guidelines, there is limited diagnostic testing recommended for outpatients, but for all patients, a chest radiograph should be used to establish the presence of pneumonia, if it can be obtained. In general, the US guidelines rely on empirical therapy, chosen on the basis of epidemiological risk factors for specific pathogens, and pathogen-directed therapy guided by diagnostic testing is not the main approach. Thus the history for all patients should focus on epidemiological clues that suggest specific pathogens. Sputum Gram's stain and culture should be done prior to therapy but only if the sputum is of good quality and can be rapidly transported to a microbiology laboratory. Blood cultures should be limited to those with severe CAP and collected prior to the initiation of antibiotic therapy. Blood cultures should also be considered for those with cavitary infiltrates, leukopenia, active alcohol abuse, chronic liver disease, severe COPD, asplenia, and pleural effusion. Finally those with severe illness and those who have failed outpatient therapy should have Legionella and pneumococcal urinary antigen testing, and if intubated an endotracheal aspirate should be sent for culture. Routine serum serological testing is not recommended. The recommendations in the latest European guidelines are similar, with limited testing recommended for outpatients. For inpatients, the European guidelines recommend blood cultures for all admitted patients and also recommend urinary antigen testing for Legionella and pneumococcus in those with severe illness, but they do not recommend routine serological testing for atypical pathogens. The European guidelines also recommend consideration of molecular diagnostic methods for pneumococcus and viruses. In the past, European guidelines endorsed the use of biomarkers such as C-reactive protein (CRP) to guide the use of antibiotics, but the new guidelines are less definitive, recommending that CRP and procalcitonin (PCT) be considered to guide severity assessment but not making their measurement mandatory.
The recommendation to limit the use of blood cultures in US guidelines is different from the approach in European guidelines but is based on a large Medicare study of 13,043 patients, which showed that it was possible to define risk factors for a true positive blood culture, and that blood cultures should only be drawn in patients with multiple risks to prevent the drawing of samples from patients whose incidence of false positive results exceeded the incidence of true positives. These risks for a positive blood culture were absence of prior antibiotics and findings associated with severe illness such as systolic BP<90 mm Hg, fever <35 or > 40°C, pulse > 125/min, BUN > 30 mg/dL, serum sodium <130, WBC <5000 or >20,000.
Recommended Diagnostic Tests
In US CAP guidelines, there is limited diagnostic testing recommended for outpatients, but for all patients, a chest radiograph should be used to establish the presence of pneumonia, if it can be obtained. In general, the US guidelines rely on empirical therapy, chosen on the basis of epidemiological risk factors for specific pathogens, and pathogen-directed therapy guided by diagnostic testing is not the main approach. Thus the history for all patients should focus on epidemiological clues that suggest specific pathogens. Sputum Gram's stain and culture should be done prior to therapy but only if the sputum is of good quality and can be rapidly transported to a microbiology laboratory. Blood cultures should be limited to those with severe CAP and collected prior to the initiation of antibiotic therapy. Blood cultures should also be considered for those with cavitary infiltrates, leukopenia, active alcohol abuse, chronic liver disease, severe COPD, asplenia, and pleural effusion. Finally those with severe illness and those who have failed outpatient therapy should have Legionella and pneumococcal urinary antigen testing, and if intubated an endotracheal aspirate should be sent for culture. Routine serum serological testing is not recommended. The recommendations in the latest European guidelines are similar, with limited testing recommended for outpatients. For inpatients, the European guidelines recommend blood cultures for all admitted patients and also recommend urinary antigen testing for Legionella and pneumococcus in those with severe illness, but they do not recommend routine serological testing for atypical pathogens. The European guidelines also recommend consideration of molecular diagnostic methods for pneumococcus and viruses. In the past, European guidelines endorsed the use of biomarkers such as C-reactive protein (CRP) to guide the use of antibiotics, but the new guidelines are less definitive, recommending that CRP and procalcitonin (PCT) be considered to guide severity assessment but not making their measurement mandatory.
The recommendation to limit the use of blood cultures in US guidelines is different from the approach in European guidelines but is based on a large Medicare study of 13,043 patients, which showed that it was possible to define risk factors for a true positive blood culture, and that blood cultures should only be drawn in patients with multiple risks to prevent the drawing of samples from patients whose incidence of false positive results exceeded the incidence of true positives. These risks for a positive blood culture were absence of prior antibiotics and findings associated with severe illness such as systolic BP<90 mm Hg, fever <35 or > 40°C, pulse > 125/min, BUN > 30 mg/dL, serum sodium <130, WBC <5000 or >20,000.