From the Guidelines
Procalcitonin levels do not provide additional diagnostic information for atypical pneumonia over symptoms and signs. When evaluating a patient with suspected pneumonia, the diagnosis should be based on clinical prediction items such as the absence of runny nose, presence of breathlessness, crackles, and diminished breath sounds at auscultation, tachycardia, and fever, with a receiver operating characteristic (ROC) curve area of 0.70 1. The addition of C-reactive protein (CRP) levels at the optimal cutoff > 30 mg/L can increase the ROC curve area to 0.77 and improve diagnostic classification 1.
In contrast, the measurement of procalcitonin concentrations added no relevant additional diagnostic information over symptoms and signs 1. The proportions of pneumonia in patients with procalcitonin concentrations of # 0.25,0.25 to 0.50, and > 0.50 mg/L were 5%, 7%, and 18%, respectively, which did not significantly differ from the diagnostic information provided by symptoms and signs 1.
For suspected atypical pneumonia, empiric treatment should be based on clinical judgment and patient-specific factors, rather than relying on procalcitonin levels. Treatment options may include macrolides, respiratory fluoroquinolones, or doxycycline, and should be guided by clinical features and response to treatment 1.
Key points to consider when evaluating a patient with suspected atypical pneumonia include:
- Clinical prediction items such as symptoms and signs
- CRP levels at the optimal cutoff > 30 mg/L
- Patient-specific factors such as comorbidities and response to treatment
- Empiric treatment options such as macrolides, respiratory fluoroquinolones, or doxycycline
- Serial measurements of clinical parameters to guide antibiotic discontinuation and treatment response 1.
From the Research
Atypical Pneumonia
- Atypical pneumonia is caused by atypical pathogens that are not detectable with Gram stain and cannot be cultured using standard methods 2.
- The most common causative organisms of atypical pneumonia are Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella species 2.
Diagnosis and Treatment
- The therapeutic approach for atypical pneumonias is different than that for typical pneumonia 2.
- A β-lactam plus a macrolide or a respiratory fluoroquinolone alone is recommended as standard empiric antibacterial therapy for non-severe adults hospitalized with community-acquired pneumonia (CAP) 3.
- Azithromycin may be an alternative to the standard 3-day azithromycin regimen in the treatment of outpatients with atypical pneumonia syndrome 4.
- The administration of a β-lactam drug plus a macrolide or tetracycline, or only fluoroquinolone should be considered to cover bacterial and atypical pneumonia, especially in elderly individuals and patients with underlying diseases 2.
Procalcitonin
- There is no direct mention of procalcitonin in the provided studies.
- However, procalcitonin is often used as a biomarker to guide antibiotic therapy in patients with pneumonia, but its role in atypical pneumonia is not explicitly discussed in the given evidence.
Antibiotic Therapy
- The evidence in support of adding empiric atypical antibacterial therapy, and specifically the addition of a macrolide, is conflicting and should be balanced with additional factors 3.
- Azithromycin is equally effective as treatment of atypical pneumonia in adult patients if given for 3 or 5 days at the same total dose 5.
- A single 1.5 g dose of azithromycin may be an alternative to the standard 3-day azithromycin regimen in the treatment of outpatients with atypical pneumonia syndrome 4.