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

>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).

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.

Ceftazidime 2 grams IV q8h
Cefepime 2 grams IV q8h
Ampicillin-sulbactam (Unasyn®) 3 grams IV q6h
Imipenem 500mg IV every 6 hours [Range: 250-1000 mg q6-8h]
Meropenem 0.5 – 1 gram IV q8h (life-threatening infection -unlabeled use: 2 grams IV q8h)
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:

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.
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.
Ciprofloxacin 400mg IV q8h