In their study, published August 10 in ACS Central Science, the researchers reported that a modified compound, dubbed fabimycin, prevented growth for more than 300 strains of drug-resistant bacterial clinical isolates, including Escherichia coli, while remaining relatively inactive toward certain gram-positive pathogens and some typically harmless bacteria that live in or on the human body.

The new molecule also reduced the amount of drug-resistant bacteria in mice with pneumonia or UTIs to preinfection levels or below, performing as well as or better than existing antibiotics at similar doses.

"Fabimycin demonstrates activity in multiple mouse models of infection caused by gram-negative bacteria, including a challenging urinary tract infection model," according to the study's authors. "Fabimycin has translational promise, and its discovery provides additional evidence that antibiotics can be systematically modified to accumulate in gram-negative bacteria and kill these problematic pathogens."