Colistin based combinations

The therapy of carbapenem-resistant Gram-negative bacteria with the combination colistin+carbapenem is increasingly used in some countries. Others prefer not using an antibiotic that shows resistance in in vitro testing as combination partner for colistin. In vitro synergy testing indicate some benefit of a colistin+carbapenem combination. Does this observation translate into clinical benefit? Limited observational data seem to favor the combination despite one combination partner being resistant. We urgently need randomized controlled clinical trials to solve this clinical question and base clinical practice on evidence rather than on observations that are prone to bias.


  • Mical Paul says:

    There are two ongoing randomized controlled trials comparing colistin monotherapy vs. colistin-carbapenem therapy for patients with severe infections caused by carbapenem-resistant Gram-negative bacteria (NCT01732250 and NCT01597973). Is anyone aware of other randomized controlled trials examining different combination therapies?

  • Heiman Wertheim says:

    Besides colistin combination therapy trials, also timing is key. Do we need to start sooner rather than wait for positive cultures with carbapenem resistant bacteria several days later?

  • Sajjad Ali says:

    we commonly see such MDR infections in our renal patients who are on heamodialysis via central line, initially we were using only colistin but since after FDA approval we started using combination with carbapenems, but without much difference in outcomes. We need to do more double blind randomised trials for final recommendations

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