New mechanisms, new worries

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.