When are antibiotics recommended for use?

When to Use Antibiotics

Antibiotics are recommended when there is a confirmed or strongly suspected bacterial infection, and should be selected based on the specific pathogen, infection site, severity of illness, and local resistance patterns. 1

Specific Indications for Antibiotic Use

Respiratory Infections

• Antibiotics are recommended for all patients with pneumonia, with S. pneumoniae being the most frequent pathogen 1
• For severe COPD exacerbations with increased sputum purulence, increased sputum volume, and increased dyspnea 1
• For community-acquired pneumonia (CAP), treatment duration should be 7-10 days for classical bacterial infections or uncomplicated CAP 1
• Longer treatment (10-14 days) is needed for suspected or proven M. pneumoniae or C. pneumoniae infections 1
• Extended treatment (21 days) is required for suspected or proven L. pneumophila or S. aureus infections or severe CAP 1

Gastrointestinal Infections

• For acute infectious bacterial diarrhea, antibiotics should only be used if the likelihood of bacterial pathogens is high enough to justify potential adverse effects 1
• For confirmed Shigella infections, ceftriaxone (categorized as a Watch antibiotic) is recommended 1
• For cholera, azithromycin is the first-choice treatment, with doxycycline as an alternative 1
• For intra-abdominal infections with adequate source control, a 4-day course is recommended for immunocompetent, non-critically ill patients 1
• For immunocompromised or critically ill patients with intra-abdominal infections, up to 7 days of antibiotics is recommended based on clinical condition 1

Skin and Soft Tissue Infections

• For cellulitis, a 5-day course of antibiotics is recommended, with extension only if the infection has not improved 2
• Clinical improvement should be assessed within 3-4 days of starting antibiotics 2

Antibiotic Selection Principles

Based on Infection Severity

• For septic shock, immediate empiric broad-spectrum antibiotics are crucial 3, 4
• For bacterial meningitis, prompt administration of effective antibiotics is essential 3
• For less severe infectious syndromes, there is no clear evidence that delayed therapy (4-8 hours) is associated with worse outcomes 3

Based on Patient Factors

• For immunocompromised patients, immediate empirical antibiotic therapy is mandatory, typically using a two-drug combination of bactericidal broad-spectrum antibiotics 5
• For patients with renal impairment, dosage adjustments are necessary (e.g., for piperacillin-tazobactam) 6

Duration and Monitoring

• Reassess antibiotic treatment in all ICU patients at 48-72 hours and de-escalate based on clinical condition and microbiological data 1
• Consider using procalcitonin to guide antibiotic discontinuation, especially for lower respiratory tract infections 1
• When plasma procalcitonin is below 0.5 ng/mL or has decreased by over 80% from peak value, consider stopping antibiotics 1
• The main criterion of response to antibiotic therapy is body temperature; fever should resolve within 2-3 days after initiation 1

Antimicrobial Stewardship Considerations

• Obtain appropriate microbiological samples before starting antibiotics 7
• Start empirical antibiotic treatment after taking cultures, tailoring to infection site, risk factors for resistant bacteria, and local susceptibility patterns 7
• De-escalate/streamline antibiotic treatment according to clinical situation and microbiological results 7
• Stop unnecessary antibiotics once absence of infection is likely 7
• For β-lactam antibiotics, maintain plasma concentrations above MIC for at least 70% of the time to increase success rates 1

Common Pitfalls to Avoid

• Treating fever without identifying the source of infection 7
• Using antibiotics for viral infections or colonization without clinical signs of infection 7
• Failing to adjust dosing based on patient characteristics (weight, renal function) 6
• Continuing broad-spectrum antibiotics when narrower options are available based on culture results 7
• Using unnecessarily prolonged courses of antibiotics when shorter durations would be effective 1, 2