Identification of Rifampicin Resistance Mutations in Escherichia coli, Including an Unusual Deletion Mutation.

Rifampicin is an effective antibiotic against mycobacterial and other bacterial infections, but resistance readily emerges in laboratory and clinical settings. We screened Escherichia coli for rifampicin resistance and identified numerous mutations to the gene encoding the β-chain of RNA polymerase (rpoB), including an unusual 9-nucleotide deletion mutation. Structural modeling of the deletion mutant indicates locations of potential steric clashes with rifampicin. Sequence conservation in the region near the deletion mutation suggests a similar mutation may also confer resistance during the treatment of tuberculosis.