What is the role of colistin and polymyxin B in the treatment of Enterobacter infections?

Updated: Jun 18, 2019
  • Author: Susan L Fraser, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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These drugs are being used more frequently to treat serious infection caused by multidrug-resistant organisms, sometimes as monotherapy or in combination with other antibiotics. Clinical experience, including documentation of success rates and attributable mortality is broadening. [39, 40] Heteroresistance to colistin was demonstrated in a few Enterobacter isolates collected from ICU patients and was best identified using broth microdilution, agar dilution, or E-test methods. [41] Polymyxin B was not as active against Enterobacter species as it was against other Enterobacteriaceae but did demonstrate an MIC50 of less than or equal to 1, with 83% of Enterobacter isolates considered susceptible. [42] One recent in vitro study documented a colistin MIC90 of 2 mcg/mL or less in more than 90% of Enterobacter isolates from Canada. [43] A study of 89 carbapenem-nonsusceptible Enterobacteriaceae isolates from China showed that polymyxin B was much more active than tigecycline. [44]


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