Antibiotic Treatment Guidelines

Patient Selection and Treatment Options

• The American College of Clinical Microbiology recommends Amoxicillin-clavulanate or second-generation cephalosporin for patients with comorbidities or modifying factors, such as COPD or recent antibiotics use, and reserving respiratory fluoroquinolones for patients with comorbidities, recent antibiotic use, or penicillin allergy 1
• The management of Community-Acquired Pneumonia (CAP) should follow a structured approach with empiric antibiotic therapy based on severity, with amoxicillin as the preferred agent in the community setting and combination therapy with a beta-lactam plus macrolide for hospitalized patients, as recommended by the Thorax journal and supported by the Infectious Diseases Society of America (IDSA) guidelines 2, 3
• First-line therapy includes amoxicillin at higher doses than previously recommended for patients without penicillin allergy, and macrolide (erythromycin or clarithromycin) for penicillin-allergic patients, according to the Thorax journal and IDSA guidelines 2, 3, 4
• Alternative regimens include oral beta-lactam (high-dose amoxicillin or amoxicillin-clavulanate) plus an oral macrolide (azithromycin or clarithromycin), macrolide (e.g., azithromycin 500mg on day 1, then 250mg daily for days 2-5), doxycycline 100mg twice daily, or respiratory fluoroquinolone (levofloxacin 750mg daily or moxifloxacin 400mg daily) 4, 5, 3, 6
• For suspected Pseudomonas infection, the IDSA guidelines provide a moderate recommendation (Level III evidence) for using an antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, meropenem) plus either ciprofloxacin or levofloxacin, an aminoglycoside and azithromycin, or an aminoglycoside and an antipneumococcal fluoroquinolone 3
• For suspected community-acquired MRSA, the IDSA guidelines provide a moderate recommendation (Level III evidence) for adding vancomycin or linezolid to the standard regimen 3
• For suspected H5N1 infection, the IDSA guidelines recommend treating with oseltamivir (Level II evidence) plus antibacterial agents targeting S. pneumoniae and S. aureus (Moderate recommendation, Level III evidence) 3

Supportive Care

• Provide appropriate oxygen therapy with monitoring of oxygen saturations, aiming to maintain PaO2 >8 kPa and SaO2 >92%, and guide oxygen therapy with repeated arterial blood gas measurements for COPD patients with ventilatory failure, as recommended by the Thorax journal 2
• Assess for volume depletion and provide IV fluids as needed, and provide nutritional support in prolonged illness, according to the Thorax journal 2
• Monitor vital signs at least twice daily, more frequently in severe cases, to ensure timely intervention, as recommended by the Thorax journal 2

Follow-up and Discharge

• Clinical review for all patients at around 6 weeks (GP or hospital clinic) is recommended to assess for clinical stability and potential underlying conditions, as outlined in the Thorax journal and IDSA guidelines 2, 3
• Chest radiograph is not needed prior to discharge if satisfactory clinical recovery, but arrange follow-up chest radiograph for patients with persistent symptoms or physical signs, or those at higher risk of underlying malignancy, according to the Thorax journal and IDSA guidelines 2, 3
• Discharge criteria include being clinically stable, having no other active medical problems, a safe environment for continued care, and the ability to tolerate oral medication, with high quality evidence 3
• The IDSA guidelines recommend a minimum treatment duration of 5 days (Level I evidence) and treatment should be discontinued when the patient is afebrile for 48-72 hours and has no more than 1 CAP-associated sign of clinical instability (Level II evidence) 3
• The British Thoracic Society recommends the following treatment durations:

Prevention

• The British Thoracic Society recommends influenza vaccination for high-risk groups (chronic lung, heart, renal, liver disease; diabetes; immunosuppression; age >65), with high quality evidence 2
• The British Thoracic Society recommends pneumococcal vaccination for those aged ≥2 years at risk of pneumococcal infection, with high quality evidence 2
• The Centers for Disease Control and Prevention recommend pneumococcal vaccination for high-risk individuals, annual influenza vaccination, and smoking cessation counseling, with high quality evidence 2

Diagnostic Testing

• Multiplex PCR testing for pneumonia provides rapid identification of pathogens with high sensitivity (89.3-100%) and specificity (88.4-100%) for detecting bacterial pneumonia, and can guide appropriate antibiotic use, with moderate quality evidence 7

• Obtain cultures before initiating antibiotics, but do not delay the administration of the first dose, with high quality evidence 3, 4

Best Practices

• Delaying antibiotic administration can be harmful, and antibiotics should be administered immediately if the illness is life-threatening or if there will be delays in admission, as recommended by the Thorax journal and IDSA guidelines 2, 3
• Inappropriate monotherapy, such as beta-lactam monotherapy, should be avoided in hospitalized patients with clinical indications, and combination therapy remains preferred, according to the Thorax journal and IDSA guidelines 2, 3
• Unnecessary radiographic follow-up can lead to unnecessary investigations and costs, and radiological improvement may lag behind clinical recovery, as outlined in the Thorax journal and IDSA guidelines 2, 3
• Inadequate follow-up planning can result in poor patient outcomes, and the hospital team is responsible for arranging the follow-up plan with both the patient and the general practitioner, as recommended by the Thorax journal and IDSA guidelines 2, 3