Review of Colistin Susceptibility Testing with Current Data

Abstract

Polymyxin E is the main drug used in the treatment of microorganisms with multidrug resistance. The positively charged nature of colistin creates difficulties in susceptibility testing. As a result of the studies, the gold standard method to determine colistin susceptibility was determined as the broth microdilution method. However, this method has not yet entered the laboratory routine in many centers in our country. Our aim in this review was to examine methods that could detect colistin susceptibility, which was very important in treatment, in the light of current data. Disk diffusion method is not recommended due to the limited diffusion of the colistin molecule into the agar. While there are studies suggesting that E-test can be a reliable and suitable alternative when compared to the reference method, there are also studies that detect a very major error rate of over 3%. Automated methods have not been able to achieve the desired categorical agreement and very major error rates in many studies. Molecular-based methods are especially used to detect the mcr gene and are especially important in determining resistance transmission. The findings of newly developed rapid tests and methods such as colistin broth disk elution are encouraging, but more studies are needed in this area.

Keywords

• colistin
• broth microdilution
• susceptibility