Department of Food Safety, Ashtown Food Research Centre, Ashtown, Dublin 15, Ireland.
Foodborne Pathog Dis. 2009 Oct;6(8):925-33. doi: 10.1089/fpd.2009.0278.
The transferability of antimicrobial resistance from lactic acid bacteria (LAB) to potential pathogenic strains was studied using in vitro methods and mating in a food matrix. Five LAB donors containing either erythromycin or tetracycline resistance markers on transferable elements were conjugally mated with LAB (Enterococcus faecalis, Lactococcus lactis) and pathogenic strains (Listeria spp., Salmonella ssp., Staphylococcus aureus, and Escherichia coli). In vitro transfer experiments were carried out with the donors and recipients using both the filter and plate mating methods. The food matrix consisted of fermented whole milk (fermented with the LAB donors) with the pathogenic recipients added as contaminants during the production process. All transconjugants were confirmed by phenotypic and molecular methods. Erythromycin resistance transfer from LAB strains to Listeria spp. was observed using both in vitro mating methods at high transfer frequencies of up to 5.1 x 10(-4) transconjugants per recipient. Also, high frequency transfer (ranging from 2.7 x 10(-8) up to 1.1 x 10(-3) transconjugants per recipient) of both erythromycin and tetracycline-resistance was observed between LAB species using in vitro methods. No resistance transfer was observed to Salmonella spp., Staphylococcus aureus, and E. coli. The only conjugal transfer observed in the fermented milk matrix was for tetracycline resistance between two LAB strains (at a transfer frequency of 2.6 x 10(-7) transconjugants per recipients). This study demonstrates the transfer of antimicrobial resistance from LAB to Listeria spp. using in vitro methods and also the transfer of resistance between LAB species in a food matrix. It highlights the involvement of LAB as a potential source of resistance determinants that may be disseminated between LAB and pathogenic strains including Listeria spp. Furthermore, it indicates that food matrices such as fermented milks may provide a suitable environment to support gene exchange.
研究了通过体外方法和在食品基质中交配将乳酸菌 (LAB) 中的抗生素耐药性转移到潜在的致病性菌株中的情况。使用含有可转移元件上的红霉素或四环素耐药标记的五个 LAB 供体与 LAB（粪肠球菌、乳球菌）和致病性菌株（李斯特菌属、沙门氏菌属、金黄色葡萄球菌和大肠杆菌）进行了共轭交配。使用过滤和平板交配方法在供体和受体之间进行了体外转移实验。食品基质由发酵全脂牛奶组成（用 LAB 供体发酵），在生产过程中添加致病性受体作为污染物。所有转导子均通过表型和分子方法确认。使用两种体外交配方法观察到来自 LAB 菌株的红霉素耐药性转移到李斯特菌属，转移频率高达每受体 5.1 x 10(-4)个转导子。此外，还观察到 LAB 种间红霉素和四环素耐药性的高频转移（每受体从 2.7 x 10(-8)到 1.1 x 10(-3)个转导子）。在发酵乳基质中未观察到对沙门氏菌属、金黄色葡萄球菌和大肠杆菌的耐药性转移。仅观察到两种 LAB 菌株之间的四环素耐药性的共轭转移（转移频率为每受体 2.6 x 10(-7)个转导子）。这项研究证明了使用体外方法从 LAB 到李斯特菌属的抗生素耐药性转移，以及在食品基质中 LAB 种间的耐药性转移。它强调了 LAB 作为抗性决定因素的潜在来源的参与，这些决定因素可能在 LAB 和包括李斯特菌属在内的致病性菌株之间传播。此外，它表明发酵乳等食品基质可能为基因交换提供合适的环境。
