What are the broad-spectrum antibiotics to start in septic shock?

Broad-Spectrum Antibiotics for Septic Shock

In septic shock, empiric combination therapy using at least two antibiotics of different antimicrobial classes should be initiated within the first hour of recognition, targeting the most likely bacterial pathogens based on the suspected infection source. 1, 2

Initial Antibiotic Selection

The choice of broad-spectrum antibiotics should be guided by:

1. Suspected infection source
2. Patient risk factors for resistant organisms
3. Local antibiogram patterns

Recommended Empiric Regimens:

• For most patients with septic shock:

  • β-lactam (extended spectrum) PLUS either an aminoglycoside OR fluoroquinolone 2
  • Common combinations include:
    • Piperacillin-tazobactam 3.375-4.5g IV every 8 hours PLUS
    • Gentamicin 5-7mg/kg IV daily OR amikacin 15mg/kg IV daily 2

• For suspected Pseudomonas aeruginosa:

  • Extended-spectrum β-lactam PLUS either an aminoglycoside OR fluoroquinolone 2
  • Example: Meropenem 1-2g IV every 8 hours PLUS gentamicin 2

• For suspected MRSA coverage:

  • Add vancomycin 15-20mg/kg IV q8-12h to the regimen 2

• For ESBL-producing organisms:

  • Carbapenem (meropenem preferred) 2

• For pneumococcal bacteremia with septic shock:

  • β-lactam PLUS macrolide 2

Timing and Administration

• Administer antibiotics within the first hour of recognizing septic shock 2, 3
• Each hour delay in antibiotic administration increases mortality risk by approximately 8% 3
• Consider extended infusion of β-lactams for improved efficacy, particularly for resistant organisms 1

Source Control

Source control measures must be implemented as soon as possible:

• Drainage of abscesses
• Debridement of infected tissue
• Removal of infected devices
• Relief of obstruction 2

De-escalation Strategy

• Re-evaluate antibiotic regimen daily 2
• De-escalate combination therapy within 3-5 days if clinical improvement occurs 1, 2
• Narrow therapy once pathogen identification and susceptibilities are established 2
• Total duration typically 7-10 days, but may be extended based on clinical response 2, 4

Special Considerations

• Neutropenic patients: Add an aminoglycoside or fluoroquinolone 2
• Suspected catheter-related infection: Add vancomycin 2
• Respiratory failure or septic shock: Consider additional coverage for Pseudomonas 2

Common Pitfalls to Avoid

• Delayed antibiotic administration beyond one hour of recognition significantly increases mortality 2
• Inadequate spectrum of coverage, especially in patients with risk factors for resistant organisms 2
• Failure to de-escalate broad-spectrum therapy once culture results are available 2
• Premature discontinuation of antibiotics leading to poor outcomes 2
• Inadequate source control contributing to persistent infection 2

The initial broad-spectrum antibiotic selection should be reassessed daily and modified based on clinical response and microbiological data to ensure optimal patient outcomes while minimizing the risk of antimicrobial resistance.