Colistin Resistance in Gram Negative Pathogens: Mechanisms, Detection, Therapeutic Challenges and Future Perspectives

Abstract

Colistin is widely regarded as a last-resort therapeutic option for infections caused by multidrug-resistant Gram-negative bacteria. In recent years, the global rise of colistin resistance among Gram-negative isolates has become a significant public health concern. Colistin resistance occurs either due to mutation or adaptation mechanisms among these multi drug resistant bacteria. The colistin resistance due to mobile colistin resistance (mcr) genes is the predominant one. Due to the clinical importance of colistin, clinicians face significant challenges in selecting appropriate antibiotic regimens against drug-resistant pathogens. Therefore, colistin susceptibility testing is essential in healthcare settings to determine whether these organisms remain susceptible to colistin.  Methods available are the colistin broth disc elution test, broth microdilution, broth macrodilution, agar dilution and automated methods like Vitek2 and Phoenix automated system. Studies from different regions  reported the high emergence of colistin resistant isolates from clinical samples. The need to avoid unnecessary usage of colistin and implement effective control measures and susceptibility testing methods in health care sector is urgent to combat this resistance.