When does evidence support the administration of prehospital antibiotics, such as ceftriaxone (a cephalosporin antibiotic), in cases of suspected severe bacterial infections?

Prehospital Antibiotics in Suspected Severe Bacterial Infections

Prehospital antibiotics should be administered in cases of suspected meningococcal disease, severe sepsis, or when hospital arrival will be delayed by more than one hour, as these situations are associated with reduced mortality when antibiotics are given promptly. 1

Key Indications for Prehospital Antibiotics

• Suspected meningococcal disease (rash in combination with signs of meningism or severe sepsis) 1
• Signs of severe sepsis (hypotension, poor capillary refill time, altered mental state) 1
• Suspected bacterial meningitis with anticipated delay of more than one hour in reaching hospital 1
• Septic shock, where administration within the first hour of recognition is associated with improved outcomes 1

Recommended Antibiotics and Dosing

• Benzylpenicillin 1200 mg IM or IV 1
• Third-generation cephalosporins such as:
  • Ceftriaxone 2 g IM or IV 1, 2
  • Cefotaxime 2 g IM or IV 1

Contraindications and Cautions

• Known anaphylaxis to penicillins or cephalosporins (antibiotics should be withheld until hospital admission) 1
• Administration of antibiotics should not delay transfer to hospital 1
• Consider the potential impact on diagnostic testing, as pre-treatment may reduce the likelihood of identifying bacteria from CSF culture 1

Evidence Supporting Early Antibiotic Administration

Recent evidence demonstrates significant mortality benefits with prehospital antibiotics:

• A 2023 study showed that patients receiving prehospital antibiotics had 69.6% lower in-hospital mortality compared to those who did not receive prehospital antibiotics 3
• Patients receiving prehospital antibiotics received treatment significantly earlier (16.0 ± 7.4 minutes vs. 50.9 ± 29.4 minutes) 3
• Implementation studies show high protocol adherence (96.2%) with low contamination rates for blood cultures (2.5%) 4
• The median time from 9-1-1 call to first antibiotic administration can be as short as 26 minutes 5

Clinical Decision Algorithm

1. Assess for sepsis criteria:

   • Suspected infection AND
   • At least 2 of: altered mental status, respiratory rate >22 breaths/min, systolic BP <100 mmHg 5

2. Determine urgency:

   • High-risk features: rapidly progressing rash, coma, hypotension, lactate >4 mmol/L, coagulopathy 1
   • Moderate risk: signs of meningism without high-risk features 1
   • Low risk: stable vital signs, no concerning features 6

3. Administer antibiotics if:

   • Any high-risk features are present OR
   • Hospital arrival will be delayed >1 hour OR
   • Suspected meningococcal disease 1

4. Proceed with hospital transfer immediately - do not delay transport to administer antibiotics 1

Common Pitfalls to Avoid

• Underestimating severity due to preserved mental status in young patients with sepsis 1
• Delaying transfer to hospital to administer antibiotics 1
• Withholding antibiotics when indicated due to concerns about diagnostic testing 1
• Failing to recognize cryptic shock (shock without hypotension) indicated by high lactate levels 1

While there is limited high-quality evidence from randomized controlled trials specifically for prehospital antibiotics, the clear mortality benefit of early antibiotics in severe infections supports their use in the prehospital setting when indicated 1, 3.