Escherichia Coli Adaptive Resistance to Clinical Antibiotics

Escherichia coli are beneficial bacteria found in human intestinal tracts. However, certain E. coli strains are pathogenic and can cause serious infections, such as neonatal sepsis and meningitis. The goal of this work is to create an awareness of the phenomenon of bacterial adaptation to antibiotics. We demonstrate that the pre-exposure of E. coli to low levels of antimicrobial agents (inducers), including broad-spectrum agents such as chloramphenicol and piperacillin, results in a decreased sensitivity of E. coli to lethal doses of the same or another antibiotic (testers), including ceftriaxone and vancomycin. We suggest that the treatment options considered for a particular E. coli infection should be based upon a review of the patient’s treatment history. Antibiotic treatments for prior infections might result in residual drug accumulation by the body acting as inducers and therefore, influence treatment effectiveness for a current infection. In this work, nearly six hundred combinations of two antibiotics were tested, and the combinations that resulted in an increase in the half maximal inhibitory concentration (IC50) to the tester by an average of 1.5 folds or more were selected. The results of this work show that E. coli can transiently adapt to antibiotics and consequently become more resistant to lethal doses of treatment antibiotics.