Acinetobacter baumannii

Acinetobacter baumannii

Background:
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Non-fermenting Gram-negative bacilli   
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[cannot catabolize glucose and therefore are not able to ferment. Non-spore forming.]
>Acinetobacter baumannii Led
>Achromobacter xylosoxidans
>Bordetella pertussis
>Burkholderia species:
     1] Burkholderia cepacia (also known as Pseudomonas cepacia) –  important
            pathogen of pulmonary infections in people with cystic fibrosis.
     2] Burkholderia pseudomallei (also known as Pseudomonas pseudomallei) 
>Elizabethkingia meningoseptica (Previously Chryseobacterium meningosepticum)
>Moraxella catarrhalis (formerly known as Branhamella catarrhalis)
>Pseudomonas aeruginosa
>Stenotrophomonas maltophilia (Initially classified as Pseudomonas maltophilia)

Acinetobacter baumannii:   

  • -Can be an opportunistic pathogen in humans.  
  • -Increasingly important as a hospital derived (nosocomial) infection . 
  • -A. baumannii is part of the ACB complex which are difficult to speciate (A. baumannii, A. calcoaceticus, and Acinetobacter genomic species 13TU).
  • -Has been identified as an ESKAPE pathogen which have a high rate of antibiotic resistance and are responsible for the majority of nosocomial infections: (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species).

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Therapy:
Important considerations:  The choice of an agent should be based on local antimicrobial sensitivities, site of infection, cost, and comorbid conditions.   Generally, the most common agents/regimens are listed first.  Listed dosages may need to be adjusted for renal dysfunction.  

  1. Ceftazidime 2 grams IV q8h
  2. Cefepime 2 grams IV q8h
  3. Ampicillin-sulbactam (Unasyn®)  3 grams IV q6h
  4. Imipenem 500mg IV every 6 hours [Range: 250-1000 mg q6-8h]
  5. Meropenem 0.5 – 1 gram IV q8h  (life-threatening infection -unlabeled use: 2 grams IV q8h)
  6. Carbapenemase producing strains –
    • Colistimethate (colistin base): 2.5 – 5mg/kg/day in 2-4 divided doses. Max 5 mg/kg/day   PLUS   [ Meropenem 1 gram IV q8h  OR  Imipenem 500mg IV every 6 hours [Range: 250-1000 mg q6-8h]

Antibiotics used in combination with agents listed above for resistant
infections or severe disease:

  1. Gentamicin or Tobramycin 1 to 2.5 mg/kg IV q8-12h or consider high-dose extended-interval dosing:  5 to 7 mg/kg q24-48h.  Adjust dosing frequency based on estimated clearance.
  2. Amikacin 5 to 7.5 mg/kg IV q8h or consider high-dose extended-interval dosing: 15-20 mg/kg q24-48h.  Adjust dosing frequency based on estimated clearance.
  3. Ciprofloxacin 400mg IV q8h

  

Acinetobacter baumannii