Acinetobacter Medication

Updated: Nov 27, 2018
  • Author: Shirin A Mazumder, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Medication

Medication Summary

Owing to the propensity of Acinetobacter to develop resistance to antibiotics, current treatment strategies remain limited. Beta-lactam antibiotics are the preferred antibacterial choices for susceptible A baumannii infections. Because of increasing resistance, carbapenems have become an increasingly critical therapeutic option for Acinetobacter infections; however, carbapenem resistance rates for A baumannii have been rising dramatically, both in the United States and globally. [1] Minocycline may retain antimicrobial activity even against strains resistant to other tetracyclines (including tigecycline), although cross-resistance has been reported. [1] In cases of nonbacteremic drug-resistant Acinetobacter pneumonia, the addition of inhaled colistin can be considered. This approach may minimize toxicity and increase antibiotic delivery to the lung. [1]

A baumannii is intrinsically multidrug resistant. Relatively few antibiotics are active against this organism. [5, 6, 7] Avoid treating colonization, but infection should be treated.

Medications to which Acinetobacter is usually sensitive include the following [4, 8, 9, 10, 11] :

  • Meropenem

  • Colistin

  • Polymyxin B

  • Amikacin

  • Rifampin

  • Minocycline

  • Tigecycline

In general, first-, second-, and third-generation cephalosporins, macrolides, and penicillins have little or no anti-Acinetobacter activity, and their use may predispose to Acinetobacter colonization. Some strains are sensitive to cefepime, ceftazidime, and sulbactam-containing beta-lactam/beta-lactamase–inhibitor drugs.

Monotherapy and combination therapy has been used successfully (eg, amikacin, minocycline, or colistin ± rifampin). Combination therapy is often discussed and suggested, but data proving lower failure rates or lower rates for the development of resistance are inconclusive.

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Antibiotics

Class Summary

Empiric antimicrobial therapy should include one of the agents listed below.

Colistimethate sodium (Coly-Mycin M)

Hydrolyzed to colistin, which acts as cationic detergent that can damage bacterial cytoplasmic membrane, causing leaking of intracellular substances and cell death.

Meropenem (Merrem)

Bactericidal broad-spectrum carbapenem antibiotic that inhibits cell wall synthesis. Effective against most gram-positive and gram-negative bacteria. Has slightly increased activity against gram-negative bacteria and slightly decreased activity against staphylococci and streptococci compared with imipenem.

Amikacin

Irreversibly binds to 30S subunit of bacterial ribosomes; blocks recognition step in protein synthesis; causes growth inhibition. For gram-negative bacterial coverage of infections resistant to gentamicin and tobramycin. Effective against P aeruginosa.

Use patient's IBW for dosage calculation. The same principles of drug monitoring for gentamicin apply to amikacin.

Polymyxin B

Binds to phospholipids, alters permeability, and damages bacterial cytoplasmic membrane.

Tigecycline (Tygacil)

A glycylcycline antibiotic that is structurally similar to tetracycline antibiotics. Inhibits bacterial protein translation by binding to 30S ribosomal subunit and blocks entry of amino-acyl tRNA molecules in ribosome A site. Indicated for complicated skin and skin structure infections caused by E coli, E faecalis (vancomycin-susceptible isolates only), S aureus (methicillin-susceptible and -resistant isolates), S agalactiae, S anginosus group (includes S anginosus, S intermedius, and S constellatus), S pyogenes, and B fragilis.

Rifampin (Rifadin)

Inhibits RNA synthesis in bacteria by binding to beta subunit of DNA-dependent RNA polymerase, which in turn blocks RNA transcription.

Minocycline (Minocin, Solodyn)

Treats infections caused by susceptible gram-negative and gram-positive organisms, in addition to infections caused by susceptible Chlamydia, Rickettsia, and Mycoplasma.

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