New mechanisms, new worries

The increasing spread of colistin resistance is resulting in untreatable infections Growing levels of resistance to available antimicrobial medicines are causing tens of thousands of deaths each year across the world ( 1 ). By 2050, the overall costs associated with antimicrobial resistance (AMR) could reduce global gross domestic product (GDP) by 2 to 3.5% ( 2 ). One concern is the development of resistance to the carbapenem antibiotics among Gram-negative bacteria, in particular, the carbapenemase-producing Enterobacteriaceae (CPE) (see the image). Enterobacteriaceae are the source of community- and hospital-acquired infections and commonly cause opportunistic infections, including pneumonia, and sometimes death ( 3 ). CPE are resistant to nearly all available antibiotics, with the exception of colistin. Emerging resistance to colistin therefore has troubling implications for patient care.