Reduce inappropriate antibiotic use is a priority of public health agencies. Community-acquired pneumonia (CAP) is one of the most important indications for antibiotic prescriptions.

In the majority of the studies of CAP, there is a large proportion of cases with no pathogen identified. Thus, the choice of the empirical antibiotic depends on the most likely pathogen, individual risk factors, comorbidities, and allergies.

Patients aged 65 years or older are often treated with amoxicillin/clavulanate or with another broad-spectrum antibiotic (third-generation cephalosporins, antipneumococcal fluoroquinolone). However, broad-spectrum antibiotic prescription in CAP is debated and concerns exist about side-effects and selective pressure for resistance. Due to lack of head-to-head antibiotic comparisons, a recent Cochrane review concluded that current evidence from Randomized Clinical Trials (RCTs) is insufficient to make evidence-based recommendations for the choice for antibiotic to be used, highlighting an important evidence gap.

Thus, the goal of the proposed trial is to compare clinical efficacy and safety of two CAP antimicrobial treatments, amoxicillin and amoxicillin/clavulanate, in patients aged 65 years or older and hospitalized in a non-intensive care unit (ICU) ward. The CAPTAIN study will be a multi-center, randomized, open, non-inferiority trial comparing clinical efficacy at Day 30 among patients ≥65 years of age, and hospitalized in a non-ICU ward, treated with narrow-spectrum (amoxicillin) versus broad-spectrum (amoxicillin/clavulanate) antimicrobial therapy for CAP. This will be a pivotal clinical trial that will provide evidence to inform CAP treatment guidelines.

Inclusion Criteria:

1. Patient aged 65 years or older with or without comorbidities defined by chronic diseases in immunocompetent patients,
2. Patient admitted to the hospital for a CAP defined by at least two clinical signs of pneumonia (cough, sputum production, dyspnea, tachypnea, or pleuritic pain, abnormal lung auscultatory sounds, fever (temperature > 38°C) or hypothermia (<36°C)), and had radiological evidence of a new infiltrate confirming pneumonia
3. Patient understanding oral and written French
4. Written informed consent obtained from patient prior to participation in the study (if the patient is unable to express in writing: consent by a trusted person).
5. Patients should be able to call and to answer to a phone call or to be with a relative who can help him to call or to answer questions notably raised by a medical staff belonging to the investigational site

Exclusion Criteria:

1. Signs of severe CAP (abscess, massive pleural effusion, serious chronic respiratory insufficiency, ICU admission)
2. Patient requiring ICU admission,
3. Estimated Glomerular Filtration Rate < 30 ml/min,
4. Known immunosuppression (asplenia, neutropenia, agammaglobulinemia, transplant, myeloma, lymphoma, known HIV and CD4<200/mm3),
5. Exacerbation of chronic obstructive pulmonary disease,
6. Life-threatening state expected to lead to possible imminent death,
7. Suspected atypical bacteria requiring combined antibiotics therapy,
8. Legionella suspected,
9. Subjects with clinical or epidemiological environment leading to suspect a healthcare associated pneumonia with antibiotic resistant pathogen (including long-term care facility)
10. Patient known to be colonized with Pseudomonas aeruginosa or Enterobacteriaceae in the respiratory tract,
11. Suspicion of aspiration pneumonia,
12. Administration of any antibiotic treatment for more than 24 hours before inclusion,
13. History of jaundice/hepatic impairment associated with amoxicillin/clavulanate acid,
14. History of bacterial pneumonia less than 1 month prior to study inclusion
15. History of hypersensitivity or allergy to beta-lactam or to any excipients included in study antibiotics,
16. Subject without health insurance,
17. Subject without home address or difficulty in terms of follow-up (vacation, job transfer, geographical distance, lack of motivation),
18. Patient under judicial protection,
19. Diagnosis confirmed of SAR-Cov2 infection (PCR Test, covid antigen rapid test, chest computed tomography (CT) scan),
20. Participation to another interventional study and having an exclusion period that is still in force during the screening phase or expected participation to another interventional study during participation to the CAPTAIN study