You isolate a pathogenic strain of E.coli from a patient and discover that this E.coli strain is resistant to an antibiotic.Common laboratory strains of E.coli are not resistant to this antibiotic, nor are any other previously isolated pathogenic E.coli strains.However, such resistance has been observed in other bacteria in the hospital in which the patient was treated.This newly discovered antibiotic resistance in E.coli is most likely due to

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The most likely explanation for the newly discovered antibiotic resistance in the pathogenic E.coli strain is horizontal gene transfer. This means that the strain acquired the resistance gene from another organism, likely another bacteria in the hospital setting where the patient was treated. Gene duplication, a mutation within a gene, and a mutation within the regulatory DNA of a gene are less likely to result in the sudden emergence of antibiotic resistance in a pathogenic strain of E.coli, and are not consistent with the observed resistance patterns in other strains.

You Isolate a Pathogenic Strain of E