title: Nisin A and Polymyxin B as Synergistic Inhibitors of Gram-positive and Gram-negative Bacteria.
abstract: Nisin A and polymyxin B were tested alone and in combination in order to test their antagonism against Listeria innocua HPB13 and Escherichia coli RR1, respectively. While the combination of both antibacterial substances was synergistically active against both target bacteria, nisin A alone did not show any inhibition of E. coli RR1. The nisin A/polymyxin B combination at 1.56/2.5 μg ml(-1) caused lysis of about 35.86 ± 0.35 and 73.36 ± 0.14% of L. innocua HPB13 cells after 3 and 18 h, respectively. Polymyxin B at 0.12 μg ml(-1) and nisin A/polymyxin B at 4.64/0.12 μg ml(-1) decreased the numbers of viable E. coli RR1 cells by about 0.23 and 0.65 log10 CFU ml(-1), respectively, compared to the control. Our data suggest that the concentration of nisin A required for the effective control of pathogenic strains Listeria spp. could be lowered considerably by combination with polymyxin B. The use of lower concentrations of nisin A or polymyxin B should slow the emergence of bacterial populations resistant to these agents.
authors.affiliation: Agriculture and Agri-Food Canada Lethbridge Research Center, Lethbridge, AB, T1J 4B1, Canada.
authors.forename: Karim
authors.initials: K
authors.lastname: Naghmouchi
authors.affiliation: ONIRIS, Rue de la Géraudière, BP 82225, 44322, Nantes Cedex 3, France. djamel.drider@oniris-nantes.fr.
authors.forename: Djamel
authors.initials: D
authors.lastname: Drider
authors.affiliation: Agriculture and Agri-Food Canada Lethbridge Research Center, Lethbridge, AB, T1J 4B1, Canada.
authors.forename: John
authors.initials: J
authors.lastname: Baah
authors.affiliation: Agriculture and Agri-Food Canada Lethbridge Research Center, Lethbridge, AB, T1J 4B1, Canada.
authors.forename: Ron
authors.initials: R
authors.lastname: Teather
keywords: Antimicrobial agents; Escherichia coli; Listeria innocua; Nisin; Polymyxin; Synergistic effect