What is the recommended treatment for Acinetobacter infections?

Treatment of Acinetobacter Infections

For Acinetobacter infections, the recommended treatment is colistin (polymyxin E) with or without a carbapenem (imipenem/cilastatin or meropenem), particularly for carbapenem-resistant Acinetobacter baumannii (CRAB) infections. 1

Treatment Recommendations by Infection Type

Pneumonia

• First-line therapy:

  • Colistin 5 mg CBA/kg IV loading dose, then 2.5 mg CBA (1.5 CrCl + 30) IV q12h ± imipenem/cilastatin 500 mg IV q6h or meropenem 2 g IV q8h 1
  • Consider adjunctive inhaled colistin 1.25-15 MIU/day in 2-3 divided doses 1

• Alternative therapy:

  • Sulbactam 6-9 g/day IV in 3-4 divided doses 1
  • Colistin + tigecycline (100 mg IV loading dose, then 50 mg IV q12h) + sulbactam 1

• Duration: At least 7 days 1

Bloodstream Infections

• First-line therapy:

  • Colistin 5 mg CBA/kg IV loading dose, then 2.5 mg CBA (1.5 CrCl + 30) IV q12h ± imipenem/cilastatin 500 mg IV q6h or meropenem 2 g IV q8h 1

• Alternative therapy:

  • Colistin + tigecycline (100 mg IV loading dose, then 50 mg IV q12h) 1
  • Colistin + sulbactam 6-9 g/day IV in 3-4 divided doses 1

• Duration: 10-14 days 1

Meningitis/Ventriculitis

• Recommended therapy:

  • Intravenous polymyxin (colistin or polymyxin B) plus intrathecal (IT) or intraventricular (IVT) administration 1
  • Alternative: IT or IVT aminoglycoside (amikacin 10-50 mg or tobramycin 5-20 mg daily) if strain is susceptible 1

• Duration: 3 weeks with monitoring of CSF sterilization 1

Special Considerations

Carbapenem-Resistant Acinetobacter baumannii (CRAB)

• For isolates sensitive only to polymyxins:
  • Intravenous polymyxins (colistin or polymyxin B) with adjunctive inhaled colistin for respiratory infections 1
  • Avoid tigecycline monotherapy for pneumonia 1
  • Avoid adjunctive rifampicin with colistin 1

Dosing Considerations

• For carbapenems: Extended infusion times (>3 hours) are recommended for each dose when treating CRAB 1, 2
• Carbapenem synergy may be observed if MIC ≤32 mg/L 1
• For colistin: Loading dose is critical due to delayed achievement of steady-state concentrations 2

Combination Therapy

• Consider combination therapy for severe infections, particularly with high bacterial load 2
• Two in vitro active antibiotics among polymyxins, aminoglycosides, tigecycline, or sulbactam combinations are recommended for severe CRAB infections 2
• Polymyxin-meropenem and polymyxin-rifampin combinations are not recommended 2

Treatment Duration

• Pneumonia/VAP: 7 days 1, 2
• Bloodstream infections: 10-14 days 1
• Meningitis/ventriculitis: 3 weeks 1
• Other infections: Based on clinical response, source control, and microbiological data 2

Important Caveats

• Aminoglycoside monotherapy is not recommended for pneumonia due to poor penetration into lungs, abscesses, and CNS 1
• Tigecycline monotherapy is not recommended for pneumonia 1
• Inhaled colistin should be administered promptly after being mixed with sterile water 1
• Nebulized antibiotics should be delivered using ultrasonic or vibrating plate nebulizers 1
• Regular monitoring of renal function is essential when using polymyxins 2

Remember that most recommendations for CRAB treatment are based on low or very low-quality evidence, and treatment should be guided by local susceptibility patterns and patient-specific factors.