From the Guidelines
The initial workup for pneumonia in outpatient adults should include a thorough clinical assessment, measurement of C-reactive protein (CRP), and chest radiography if abnormal vital signs are present, as suggested by the 2019 Chest guideline and expert panel report 1.
Clinical Assessment
The clinical assessment should focus on symptoms and signs suggestive of pneumonia, such as cough, dyspnea, pleural pain, sweating/fevers/shivers, aches and pains, temperature 38C or greater, tachypnea, and new and localizing chest examination signs 1. The absence of runny nose and the presence of breathlessness, crackles, and/or diminished breath sounds on auscultation, tachycardia, and fever (38C or greater) are also suggestive of pneumonia.
Laboratory Investigations
- Measurement of CRP is recommended because it strengthens both the diagnosis and exclusion of pneumonia when added to clinical features such as fever, pleural pain, dyspnea, and tachypnea, and signs on physical examination of the chest 1.
- A CRP level of 30 mg/L or higher, in addition to suggestive symptoms and signs, increases the likelihood of pneumonia, while a level below 10 mg/L or between 10-50 mg/L in the absence of dyspnea and daily fever makes pneumonia less likely 1.
- Procalcitonin measurement is not routinely recommended for outpatient adults with acute cough due to suspected pneumonia 1.
- Routine microbiological testing is not suggested unless the results may lead to a change in therapy 1.
Imaging
- Chest radiography is recommended for outpatient adults with acute cough and abnormal vital signs secondary to suspected pneumonia to improve diagnostic accuracy 1.
Treatment
- Empiric antibiotics should be used as per local and national guidelines when pneumonia is suspected in settings where imaging cannot be obtained 1.
- Antiviral treatment should be initiated within 48 hours of symptom onset for outpatient adults with acute cough and suspected influenza, as per Centers for Disease Control and Prevention advice 1.
Differential Diagnoses
Important differential diagnoses to consider include:
- Acute bronchitis
- Pulmonary embolism
- Heart failure
- Lung cancer
- Tuberculosis
- Interstitial lung disease
- Aspiration pneumonitis Distinguishing features of these conditions, such as the absence of infiltrates on imaging in bronchitis, risk factors and sudden onset for pulmonary embolism, and cardiac findings in heart failure, should be taken into account when making a diagnosis.
From the Research
Pneumonia Investigations Work-Up and Plan
- The work-up for pneumonia typically involves a comprehensive evaluation, including blood, urine, and sputum cultures, to confirm the etiology prior to initiation of antibiotic therapy 2.
- Empiric therapy can be chosen based on an assessment of patient risk factors for specific organisms and on an evaluation of the severity of illness present 3.
- The selection of the most appropriate antimicrobial agent(s) must consider the likely etiologies and anticipated resistance patterns 2.
Differential Diagnoses
- Nosocomial pneumonia: empiric therapy must be directed at multi-drug-resistant, gram-negative bacilli and methicillin-resistant Staphylococcus aureus (MRSA), especially in patients with a history of prolonged hospitalization and recent antibiotic use 2.
- Community-acquired pneumonia (CAP): antibiotic selection, severity of CAP, single vs multiple pathogens, pharmacokinetic considerations, antibiotic resistance, and pharmacoeconomic implications must be considered 4.
- Hospital-acquired pneumonia (HAP), ventilator-associated pneumonia (VAP), and health care-associated pneumonia (HCAP): guideline-based empiric antibiotic therapy is crucial, with a focus on prompt initiation of appropriate therapy 5.
Treatment Options
- Combination therapy with a third-generation cephalosporin and a macrolide may be preferred over monotherapy with a fluoroquinolone for hospitalized patients with moderate to severe CAP 6.
- New antibiotics, such as daptomycin, linezolid, and tigecycline, are available for the treatment of multi-drug-resistant, gram-positive pathogens 2.
- Initial empiric broad-spectrum antibiotic therapy is necessary for treatment of patients with serious infections, followed by tailored therapy based on the patient's initial response and susceptibility test results 2.