Abstract

No antibiotic has been shown to “overcome” a bacterial drug-resistance mechanism. As more antibiotics are developed, even greater numbers of resistant strains emerge and pose a constant public health threat. One solution is to improve the efficacy of existing antibiotics with other molecular inhibitors (i.e. co-drugs). Potential targets for such inhibitors might be bacterial proteins that provide intrinsic antibiotic resistance. In order to identify these targets, we have tested a defined and virtually complete collection of 4,000 viable single gene knockouts in Escherichia coli for their limited abilities to grow in the presence of one or more of 22 antibiotics. Using a high throughput screening approach of each antibiotic at a subinhibitory concentration, we identified 300 mutants to make up the comprehensive sensitivity profile. Collectively, this profile enabled us to rapidly characterize these antibiotics with respect to their mechanisms of action, to construct a sensitive chromogenic test for detecting residual levels of antibiotics, and to identify small molecules to serve as leading compounds. In the future, these compounds may be used to synthesize derivatives as co-drugs that could improve the efficiencies of existing antibiotics.