Joint Tolerance to β-Lactam and Fluoroquinolone Antibiotics in Escherichia coli Results from Overexpression of hipA

The basis of joint tolerance to β-lactam and fluoroquinolone antibiotics in Escherichia coli mediated by hipA was examined. An antibiotic tolerance phenotype was produced by overexpression of hipA under conditions that did not affect the growth rate of the organism. Overexpressing hipA probably decreases the period in which bacteria are susceptible to the antibiotics by temporarily affecting some aspect of chromosome replication or cell division.