What is the illness script of Community-Acquired Pneumonia (CAP)?

From the Guidelines

Community-acquired pneumonia (CAP) is a respiratory infection acquired outside of a healthcare setting, characterized by inflammation of the lung parenchyma, and the illness script typically includes patients presenting with fever, productive cough with purulent sputum, dyspnea, pleuritic chest pain, and sometimes hemoptysis, as outlined in the most recent guideline by the American Thoracic Society and Infectious Diseases Society of America 1. The illness script of CAP includes a range of clinical presentations, from mild to severe, and can be influenced by various factors such as age, comorbidities, and the presence of risk factors for certain pathogens.

• Key features of the illness script include:
  • Symptoms: fever, cough, dyspnea, pleuritic chest pain, and hemoptysis
  • Physical examination findings: tachypnea, tachycardia, crackles or rales on auscultation, and dullness to percussion over affected lung areas
  • Risk factors: advanced age, smoking, COPD, immunosuppression, alcoholism, and recent viral respiratory infections
  • Common causative organisms: Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, and respiratory viruses
• Diagnosis is typically confirmed by chest X-ray showing infiltrates, along with supporting laboratory findings such as leukocytosis and elevated inflammatory markers.
• Treatment involves empiric antibiotics based on likely pathogens, with outpatient therapy often consisting of amoxicillin or doxycycline for mild cases, and combination therapy with a beta-lactam and a macrolide for more severe cases requiring hospitalization, as recommended in the guideline 1.
• Patients should be assessed for severity using tools like CURB-65 or Pneumonia Severity Index to determine the appropriate treatment setting, and supportive care includes hydration, antipyretics, and oxygen supplementation as needed, as outlined in the guideline 1.

From the FDA Drug Label

14.2 Community-Acquired Pneumonia: 7 to 14 Day Treatment Regimen

Adult inpatients and outpatients with a diagnosis of community-acquired bacterial pneumonia were evaluated in 2 pivotal clinical studies In the first study, 590 patients were enrolled in a prospective, multicenter, unblinded randomized trial comparing levofloxacin 500 mg once daily orally or intravenously for 7 to 14 days to ceftriaxone 1 to 2 grams intravenously once or in equally divided doses twice daily followed by cefuroxime axetil 500 mg orally twice daily for a total of 7 to 14 days Patients assigned to treatment with the control regimen were allowed to receive erythromycin (or doxycycline if intolerant of erythromycin) if an infection due to atypical pathogens was suspected or proven. Clinical and microbiologic evaluations were performed during treatment, 5 to 7 days posttherapy, and 3 to 4 weeks posttherapy Clinical success (cure plus improvement) with levofloxacin at 5 to 7 days posttherapy, the primary efficacy variable in this study, was superior (95%) to the control group (83%). The 95% CI for the difference of response rates (levofloxacin minus comparator) was [-6,19] In the second study, 264 patients were enrolled in a prospective, multi-center, non-comparative trial of 500 mg levofloxacin administered orally or intravenously once daily for 7 to 14 days. Clinical success for clinically evaluable patients was 93% For both studies, the clinical success rate in patients with atypical pneumonia due to Chlamydophila pneumoniae, Mycoplasma pneumoniae, and Legionella pneumophila were 96%, 96%, and 70%, respectively.

The illness script of community-acquired pneumonia includes:

• Causative microorganisms: Chlamydophila pneumoniae, Haemophilus influenzae, Legionella pneumophila, Moraxella catarrhalis, Mycoplasma pneumoniae, Staphylococcus aureus, and Streptococcus pneumoniae 2
• Clinical presentation: symptoms of bacterial pneumonia, such as cough, fever, and radiological findings 2
• Treatment: antibiotics, such as levofloxacin or azithromycin, for 7 to 14 days 2 3
• Response to treatment: clinical success rates of 90-95% with levofloxacin and 93% with azithromycin 2 3

From the Research

Illness Script of Community-Acquired Pneumonia

The illness script of community-acquired pneumonia (CAP) involves the diagnosis and treatment of the condition, which is a common cause of morbidity and mortality worldwide 4.

Diagnosis and Treatment

• The diagnosis of CAP is typically based on clinical and radiological findings, and the treatment is often empirical, covering both typical and atypical pathogens 4.
• The choice of antibiotic therapy depends on various factors, including the severity of the disease, the presence of comorbidities, and the likelihood of antibiotic resistance 5.
• Beta-lactams, such as amoxicillin/clavulanate, have been traditionally used to treat CAP, but the increasing prevalence of antibiotic resistance has led to the use of alternative antibiotics, such as fluoroquinolones and macrolides 4, 6.

Antibiotic Options

• Fluoroquinolones, such as levofloxacin and moxifloxacin, have been shown to be effective in treating CAP, with clinical success rates of > 90% 4.
• Macrolides, such as azithromycin, have also been used to treat CAP, with clinical success rates comparable to those of fluoroquinolones 7.
• Doxycycline has been recommended as a treatment option for non-severe CAP in adults, with a systematic review and meta-analysis showing comparable efficacy to macrolides and fluoroquinolones 8.

Treatment Duration and Regimens

• The duration of antibiotic therapy for CAP can vary, with some studies showing that short-course regimens (e.g., 3-5 days) can be as effective as longer courses (e.g., 7-10 days) 7, 4.
• Combination therapy with a beta-lactam and a macrolide or an antipneumococcal fluoroquinolone alone can be used to treat CAP, especially in patients with comorbidities or recent antibiotic therapy 4.