The antimicrobial actions of three common plant-derived terpenoids (i.e., carvacrol, thymol and eugenol) were compared to those of a typical quaternary ammonium biocide (i.e., benzalkonium chloride; BAC), against both planktonic and biofilm cells of two widespread Staphylococcus species (i.e., S. aureus and S. epidermidis). The minimum inhibitory and bactericidal concentrations (MICs, MBCs) of each compound against the planktonic cells of each species were initially determined, together with their minimum biofilm eradication concentrations (MBECs). Various concentrations of each compound were subsequently applied, for 6 min, against each type of cell, and survivors were enumerated by agar plating to calculate log reductions and determine the resistance coefficients (Rc) for each compound, as anti-biofilm effectiveness indicators. Sessile communities were always more resistant than planktonic ones, depending on the biocide and species. Although lower BAC concentrations were always needed to kill a specified population of either cell type compared to the terpenoids, for the latter, the required increases in their concentrations, to be equally effective against the biofilm cells with respect to the planktonic ones, were not as intense as those observed in the case of BAC, presenting thus significantly lower Rc. This indicates their significant anti-biofilm potential and advocate for their further promising use as anti-biofilm agents.

中文翻译：

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与季铵杀生物剂相比，常见的植物来源的萜类化合物目前对葡萄球菌的抗生物膜潜力增加。

比较了三种常见植物来源的萜类化合物（即香芹酚，百里酚和丁子香酚）与典型季铵杀生物剂（即苯扎氯铵； BAC）对两种广泛的葡萄球菌物种的浮游和生物膜细胞的抗菌作用（即金黄色葡萄球菌和表皮葡萄球菌）。首先确定每种化合物对每种物种的浮游细胞的最小抑制和杀菌浓度（MIC，MBC），以及它们的最小生物膜清除浓度（MBEC）。随后将各种浓度的每种化合物对每种类型的细胞施加6分钟，并通过琼脂平板计数求出存活者，以计算对数减少并确定每种化合物的抗系数（Rc），作为抗生物膜有效性指标。取决于杀生物剂和物种，无性群落总是比浮游生物更具抗性。尽管与萜类化合物相比，总是需要较低的BAC浓度来杀死任何一种细胞类型的特定种群，但对于后者，所需的浓度增加了，与浮游生物一样有效对抗生物膜细胞，其强度不如BAC观察到的强，因此Rc显着降低。这表明它们具有巨大的抗生物膜潜力，并提倡将其进一步用作抗生物膜剂。