Should I administer empirical antibiotics?

Empirical Antibiotic Therapy: When and How to Use It

Empirical antibiotics should only be administered in specific clinical scenarios where bacterial infection is highly suspected or confirmed, as inappropriate use contributes to antibiotic resistance without improving patient outcomes. 1

Appropriate Indications for Empirical Antibiotics

• Infectious diarrhea: Empiric antibiotics are NOT recommended for most cases of acute watery diarrhea without recent international travel 1

• Exceptions for diarrhea where empiric antibiotics may be warranted:

  • Infants < 3 months of age with suspected bacterial etiology 1
  • Immunocompromised patients with severe illness and bloody diarrhea 1
  • Patients with fever documented in a medical setting, abdominal pain, bloody diarrhea, and signs of bacillary dysentery 1
  • Recent international travelers with body temperatures ≥38.5°C and/or signs of sepsis 1

• COVID-19: Empiric antibiotics are NOT recommended for patients with COVID-19 unless there is clinical suspicion of bacterial superinfection 1

  • WHO recommends against empiric antibiotics in mild COVID-19 1
  • For moderate COVID-19, antibiotics should only be considered with clinical concern for bacterial pneumonia 1
  • For COVID-19 patients with shock, empiric antibiotics may be warranted as part of standard sepsis management 1

• Sepsis: Patients with clinical features of sepsis should receive prompt empiric broad-spectrum antimicrobial therapy after appropriate cultures are collected 1, 2

• Central venous catheter infections: Empiric antibiotic therapy should be started when there are clinical signs of infection, without waiting for blood culture results 1

• Diabetic foot infections: All clinically infected wounds should receive antibiotic therapy, but uninfected wounds should not be treated with antibiotics 1

Contraindications for Empirical Antibiotics

• Clinically uninfected wounds 1
• Most cases of acute watery diarrhea without international travel 1
• Persistent watery diarrhea lasting 14 days or more 1
• Asymptomatic contacts of people with acute or persistent watery diarrhea 1
• Asymptomatic contacts of people with bloody diarrhea 1
• Infections attributed to STEC O157 and other STEC that produce Shiga toxin 2 1
• Mild COVID-19 without signs of bacterial infection 1, 3

Appropriate Antibiotic Selection

• For infectious diarrhea (when indicated):

  • Adults: Fluoroquinolone (e.g., ciprofloxacin) or azithromycin, depending on local susceptibility patterns and travel history 1
  • Children: Third-generation cephalosporin for infants < 3 months or those with neurologic involvement, or azithromycin 1

• For central venous catheter infections:

  • Vancomycin is recommended as empiric therapy due to high prevalence of coagulase-negative staphylococci and MRSA 1
  • Daptomycin can be used in cases with higher risk for nephrotoxicity or high prevalence of MRSA with vancomycin MIC ≥2 μg/ml 1
  • For severe symptoms (sepsis, neutropenia), add coverage for Gram-negative bacilli with fourth-generation cephalosporins, carbapenems, or β-lactam/β-lactamase combinations 1

• For diabetic foot infections:

  • Consider empiric coverage against MRSA in patients with prior MRSA history, high local MRSA prevalence, or severe infection 1

• For nosocomial pneumonia:

  • Piperacillin-tazobactam 4.5g every six hours plus an aminoglycoside 1, 4
  • Continue aminoglycoside in patients from whom P. aeruginosa is isolated 4

Best Practices for Empirical Antibiotic Use

• Obtain appropriate microbiological samples BEFORE starting antibiotics 5, 2

• Start empiric treatment promptly in cases of sepsis, as delays increase mortality 1, 2

• Tailor empiric therapy to:

  • Site of infection 5
  • Risk factors for multidrug-resistant bacteria 1
  • Local microbiology and susceptibility patterns 1, 5
  • Patient's recent antibiotic exposure (choose a different class if patient recently received antibiotics) 1

• Use appropriate dosing based on patient characteristics and site of infection 1, 4

• Modify or discontinue antibiotics when a clinically plausible organism is identified 1, 5

• De-escalate therapy based on culture results and clinical response 1, 5

• Limit duration of therapy to the shortest effective course 5

Common Pitfalls to Avoid

• Overuse of empiric antibiotics: Bacterial coinfection at ICU admission for COVID-19 is uncommon (5.5%), yet empiric antibiotics are frequently prescribed 3
• Inappropriate antibiotic selection: Increases 30-day mortality (20.1% vs 11.8%) and prolongs hospital stay by at least 2 days 2
• Failure to de-escalate: Continuing broad-spectrum therapy when narrower options are available contributes to resistance 5
• Treating colonization: In the absence of clinical signs of infection, colonization rarely requires antimicrobial treatment 5
• Treating fever without identifying source: Investigate the root cause of fever prior to starting antibiotics 5
• Ignoring local resistance patterns: Treatment failure is more likely when empiric therapy doesn't match local resistance patterns 6

Special Considerations

• Immunocompromised patients: Lower threshold for empiric antibiotics may be appropriate 1
• Renal impairment: Adjust antibiotic dosing based on creatinine clearance 4
• Recent antibiotic use: Increases risk of resistant organisms; select a different antibiotic class 1
• Healthcare-associated infections: Higher risk of resistant organisms; broader empiric coverage may be needed 1

Remember that appropriate empiric antibiotic therapy can improve outcomes when bacterial infection is present, but inappropriate use contributes to resistance without benefit. Always reassess the need for continued antibiotics as more clinical and microbiological data become available 1, 5.