Growth inhibition of Acinetobacter by 5-chloro-indole-3-acetic acid

The Acinetobacter calcoaceticus-baumannii complex includes high-priority, multidrug-resistant pathogens for which novel antibiotics are urgently needed. Many bacterial strains from this complex harbor a so-called iac gene cluster that codes for the catabolism of indole-3-acetic acid (IAA). Here, we demonstrate that possession and expression of iac genes represent an Achilles’ heel for Acinetobacter species, which can be exploited to suppress bacterial growth by treatment with IAA and its analog 5-chloro-IAA. IMPORTANCE Acinetobacter baumannii is a deadly bacterial pathogen and one of the leading causes of hospital-acquired infections worldwide. It is also known for its resistance to many antibiotics currently available. In this study, we show that Acinetobacter bacteria choke on a mixture of IAA and 5-chloro-IAA, offering a path to the discovery and development of a novel drug treatment.