Poultry and its products are an economical source of high-quality protein for human consumption. In animal agriculture, antibiotics are used as therapeutic agents to treat disease in livestock, or as prophylactics to prevent disease and in so doing enhance production. However, the extensive use of antibiotics in livestock husbandry has come at the cost of increasingly drug-resistant bacterial pathogens. This highlights an urgent need to find effective alternatives to be used to treat infections, particularly in poultry and especially caused by drug-resistant Salmonella strains. In this study, we describe the combined effect of extracts of the red seaweeds Chondrus crispus (CC) and Sarcodiotheca gaudichaudii (SG) and compounds isolated from these in combinations with industry standard antibiotics (i.e., tetracycline and streptomycin) against Salmonella Enteritidis. Streptomycin exhibited the higher antimicrobial activity against S. Enteritidis, as compared to tetracycline with a MIC₂₅ and MIC₅₀ of 1.00 and 1.63 μg/mL, respectively. The addition of a water extract of CC at a concentration of 200 µg/mL in addition to tetracycline significantly enhanced the antibacterial activity (log CFU/mL 4.7 and 4.5 at MIC₂₅ and MIC₅₀, respectively). SG water extract, at 400 and 800 µg/mL (p = 0.05, n = 9), also in combination with tetracycline, showed complete inhibition of bacterial growth. Combinations of floridoside (a purified red seaweed component) and tetracycline (MIC₂₅ and MIC₅₀) in vitro revealed that only the lower concentration (i.e., 15 μg/mL) of floridoside potentiated the activity of tetracycline. Sub-lethal concentrations of tetracycline (MIC₅₀ and MIC₂₅), in combination with floridoside, exhibited antimicrobial activities that were comparable to full-strength tetracycline (23 μg/mL). Furthermore, the relative transcript levels of efflux-related genes of S. Enteritidis, namely marA, arcB and ramA, were significantly repressed by the combined treatment of floridoside and tetracycline, as compared to control MIC treatments (MIC₂₅ and MIC₅₀). Taken together, these findings demonstrated that the red seaweeds CC and SG and their selected, purified components can be used to increase the lifetime of existing, patented antibiotics and can also help to reduce costly (economic and environmental) therapeutic and prophylactic use of antibiotics in poultry. To our knowledge, this is the first report of antibiotic potentiation of existing industry standard antibiotics using red seaweeds and their selected extracts against S. Enteritidis.

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精选栽培红海藻及其成分与四环素合用对家禽病原菌沙门氏菌的抗菌作用

家禽及其产品是供人类消费的优质蛋白质的经济来源。在畜牧业中，抗生素被用作治疗牲畜疾病的治疗剂，或用作预防疾病的预防剂，从而提高了产量。但是，在畜牧业中广泛使用抗生素是以增加耐药菌病原体为代价的。这凸显了迫切需要找到有效的替代品来治疗感染，尤其是在禽类中，尤其是由耐药沙门氏菌引起的感染。在这项研究中，我们描述了红海藻软骨碎（CC）和Sarcodiotheca gaudichaudii提取物的联合作用（SG）和从中分离出的化合物与针对肠炎沙门氏菌的工业标准抗生素（即四环素和链霉素）组合使用。链霉素表现出对更高的抗微生物活性S.肠炎，相比于四环素与MIC ₂₅和MIC ₅₀ 1.00 1.63微克/毫升，分别。除四环素外，添加浓度为200 µg / mL的CC水提取物可显着增强抗菌活性（MIC ₂₅和MIC ₅₀分别为log CFU / mL 4.7和4.5 ）。SG水提取物，浓度为400和800 µg / mL（p = 0.05，n= 9），也与四环素联用，显示出对细菌生长的完全抑制。floridoside（一种纯化的红海藻成分）和四环素（MIC ₂₅和MIC ₅₀）的体外组合显示，只有较低浓度（即15μg/ mL）的floridoside增强了四环素的活性。亚致死浓度的四环素（MIC ₅₀和MIC ₂₅）与氟吡菊酯组合，具有与全强度四环素（23μg/ mL）相当的抗菌活性。此外，外排相关基因的相对转录水平S.肠炎，即和marA，arcB和拉玛与对照MIC处理（MIC ₂₅和MIC ₅₀）相比，氟吡菊酯和四环素的联合处理显着抑制了，。综上所述，这些发现表明，红海藻CC和SG及其选定的纯化成分可用于延长现有的已获专利的抗生素的寿命，还有助于减少抗生素的昂贵（经济和环境）治疗和预防使用。家禽。据我们所知，这是使用红海藻和他们的选择对现有的提取物行业标准的抗生素抗生素增强的第一份报告S.肠炎。