Illustration of the antibiotic zosurabalpin (red) trapping a lipopolysaccharide molecule (orange) in an intermembrane transporter (blue) from Acinetobacter baylyi (centre). This interrupts the assembly of the outer membrane of the bacterial cell wall, leading to the death of the bacterium. Acinetobacter baylyi is a gram-negative bacterium which has multi-drug resistance. The discovery of zosurabalpin was announced in January 2024 and was the first new antibiotic shown to be effective against Carbapenem-resistant Acinetobacter baumannii (CRAB) in 50 years.