Effect of the inhibitors phenylalanine arginyl β-naphthylamide (PAβN) and 1-(1-naphthylmethyl)-piperazine (NMP) on expression of genes in multidrug efflux systems of Escherichia coli isolates from bovine mastitis.

The multidrug efflux system in bacteria can reduce antibiotic concentration inside the cell, leading to failure in the treatment of bacterial diseases. This study evaluated the influence of two efflux pump inhibitors (EPIs), phenylalanine arginyl β-naphthylamide (PAβN) and 1-(1-naphthylmethyl)-piperazine (NMP), on the gene expreβion of three multidrug efflux systems, AcrAB, AcrEF and EmrAB in Escherichia coli bovine mastitis isolates resistant to ampicillin and sulfamethoxazole/trimethoprim simultaneously. Each isolate had at least three multidrug efflux system genes. The acrA and acrB had the lowest expreβion levels in all treatments, while the emrA or emrB showed the highest expreβion levels in the presence of ampicillin, sulfamethoxazole/trimethoprim, PAßN and NMP. EPIs also contributed to the decrease in arcF expreβion when used in combination with ampicillin treatment. Since PAβN showed stronger effects than NMP, it may serve as an alternative to aβist in the antimicrobial therapy of mastitis. [ABSTRACT FROM AUTHOR]