The Enterobacteriaceae, and specifically Escherichia coli, are among the bacteria that have been studied in greatest depth in an attempt to clarify the phenomena underlying antibiotic resistance, especially in human medicine. E.coli has been identified as an indicator micro‐organism (‘alert organism surveillance’), as it is ubiquitous and highly prone to horizontal resistance gene transfer (13). Quinolones and fluoroquinolones are broad‐ spectrum antibiotics that are used in both human and veterinary medicine and act on a wide range of bacteria. Resistance to nalidixic acid is considered an indicator of increased resistancetofluoroquinolones(11