Abstract:

Purpose: In this study, lactic acid bacteria (LAB) were separated from horse milk and horse milk products with
national characteristics and special functions in pastoral areas of Inner Mongolia. In order to ensure better application of
the isolated strains in the fermentation industry, it is necessary to test their drug resistance and explore if LAB possess an
active efflux system mediating quinolone resistance. Methods: Double dilution method was used to determine the minimum
inhibitory concentration (MIC) of quinolone. The proton pump inhibitor reserpine was combined with fluorescence
spectrophotometry to detect the ciprofloxacin intakes of drug-resistant strains and control strains. Results: The accumulation
of ciprofloxacin increased significantly in drug-resistant strains HZ18, HZ28, NN3 and NN4 after adding reserpine.
Conclusion: Lactic acid bacteria may possess an active efflux system mediating quinolone resistance.

Key words: lactic acid bacteria, quinolone, minimum inhibitory concentration (MIC), fluorescence spectrophotometry, active efflux system