What intravenous (IV) antibiotics are given for head injuries?

Intravenous Antibiotics for Head Injuries

For head injuries with suspected bacterial meningitis, the first-line intravenous antibiotic is ceftriaxone 2g IV every 12 hours or cefotaxime 2g IV every 6 hours. 1

Initial Empiric Therapy Algorithm

• All patients with suspected meningitis or meningococcal sepsis should receive 2g ceftriaxone IV every 12 hours or 2g cefotaxime IV every 6 hours 1
• Patients aged 60 or over should receive 2g IV ampicillin/amoxicillin 4-hourly in addition to a cephalosporin to cover Listeria monocytogenes 1
• Immunocompromised patients (including diabetics and those with alcohol misuse history) should also receive 2g IV ampicillin/amoxicillin 4-hourly in addition to a cephalosporin 1
• If the patient has traveled within the last 6 months to a country with high rates of penicillin-resistant pneumococci, add vancomycin 15-20 mg/kg IV every 12 hours or rifampicin 600mg twice daily 1
• For patients with clear history of anaphylaxis to penicillins or cephalosporins, use IV chloramphenicol 25 mg/kg every 6 hours 1

Pathogen-Specific Therapy

Neisseria meningitidis

• Continue ceftriaxone 2g IV every 12 hours or cefotaxime 2g IV every 6 hours 1
• Alternative: benzylpenicillin 2.4g IV every 4 hours 1
• Duration: 5 days if patient has recovered 1

Streptococcus pneumoniae

• For penicillin-sensitive strains: benzylpenicillin 2.4g IV every 4 hours or continue cephalosporin 1
• For penicillin-resistant, cephalosporin-sensitive strains: continue ceftriaxone 2g IV every 12 hours or cefotaxime 2g IV every 6 hours 1
• For penicillin and cephalosporin-resistant strains: ceftriaxone or cefotaxime plus vancomycin 15-20 mg/kg IV every 12 hours (adjust according to serum levels) or rifampicin 600mg twice daily 1
• Duration: 10-14 days depending on clinical response 1

Haemophilus influenzae

• Continue ceftriaxone 2g IV every 12 hours or cefotaxime 2g IV every 6 hours 1
• Duration: 10 days 1

Listeria monocytogenes

• Amoxicillin 2g IV every 4 hours 1
• Alternative: co-trimoxazole 10-20 mg/kg (of trimethoprim component) in 4 divided doses 1
• Duration: 21 days 1

Enterobacteriaceae

• Continue ceftriaxone 2g IV every 12 hours or cefotaxime 2g IV every 6 hours 1
• For suspected ESBL-producing organisms: meropenem 2g IV every 8 hours 1
• Duration: 21 days 1

Important Clinical Considerations

• Ceftriaxone penetrates inflamed meninges well and has bactericidal activity against common meningeal pathogens 1
• After the first 24 hours of therapy in patients who are clinically improving, ceftriaxone can be given as 4g once daily for outpatient therapy 1, 2
• For patients with no identified pathogen who have recovered by day 10, treatment can be discontinued 1
• Cerebrospinal fluid (CSF) ceftriaxone concentrations 24 hours after dosing are typically 10-100 times higher than the minimum inhibitory concentration (MIC) of pathogenic bacteria 3

Common Pitfalls to Avoid

• Do not rely on first-generation cephalosporins for meningitis treatment as they have inadequate CSF penetration 4
• Do not use tigecycline for carbapenem-resistant infections on pharmacodynamic grounds 5
• Do not forget to add ampicillin/amoxicillin for patients ≥60 years old or immunocompromised patients, as Listeria coverage is essential 1
• Do not continue empiric antibiotics beyond 10 days in patients with no identified pathogen who have clinically recovered 1
• Do not rely on vancomycin alone for resistant pneumococcal meningitis as CSF penetration may be inadequate, especially when dexamethasone is administered 1

By following this evidence-based approach to antibiotic selection for head injuries with suspected meningitis, you can optimize patient outcomes while practicing good antibiotic stewardship.