Clostridioides difficile colitis overgrowth occurs when the normal gut microbiome becomes disrupted, often due to antibiotics. Effective treatment remains elusive, due partly to the persistence of its spores in the gut. Natural substances like manuka honey offer an alternative antimicrobial mechanism of action to conventional antibiotics. We investigated the antibiotic activity of manuka honey against 20 C. difficile isolates. The minimum inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBC) of manuka honeys of methylglyoxal (MGO) grades 30⁺, 100⁺, 250⁺, and 400⁺ were determined based on broth microdilution. Sporicidal activity was assessed in a range of honey concentrations by enumerating total viable cell and spore counts at 0–96 h after organism inoculation. The MICs of C. difficile ranged from 4% to >30% (w/v). MIC₅₀ for the four MGO grades were similar at 10–14%. MBC results for the majority of isolates were distributed bimodally at MBC/MIC ratios ≤4 or MBC >30%. Growth kinetics in honey showed total viable cell counts remaining >10⁵ colony-forming units (CFU)/mL at all time points, whereas spore counts remained within 1-log of baseline (10² CFU/mL) in honey but steadily increased in the drug-free control to >10⁵ CFU/mL by 96 h. Manuka honey demonstrated variable inhibitory and bactericidal activity against C. difficile. MGO grade had no noticeable impact on overall MIC distributions or bactericidal activity. Although manuka honey could inhibit spore proliferation, it did not eradicate spores completely.

中文翻译：

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麦卢卡蜂蜜对艰难梭菌的杀菌活性和抑菌作用

当正常肠道微生物组被破坏（通常是由于抗生素）时，艰难梭状芽胞杆菌就会过度生长。有效治疗仍然难以捉摸，部分原因是其孢子在肠内的持续存在。麦卢卡蜂蜜等天然物质提供了常规抗生素替代的抗菌作用机制。我们研究了麦卢卡蜂蜜对20种艰难梭菌分离物的抗生素活性。甲基乙二醛（MGO）等级30 ⁺，100 ⁺，250 ⁺和400 ⁺的麦卢卡蜂蜜的最低抑菌浓度（MICs）和最低杀菌浓度（MBC）根据肉汤微量稀释确定。通过计数接种生物体后0–96 h的总活细胞和孢子计数，评估了一系列蜂蜜浓度下的杀孢活性。艰难梭菌的MIC范围为4％至> 30％（w / v）。四个MGO等级的MIC ₅₀相似，为10–14％。大多数分离株的MBC结果以MBC / MIC比≤4或MBC> 30％的形式双峰分布。蜂蜜中的生长动力学表明，在所有时间点，总活细胞计数均保持> 10 ⁵集落形成单位（CFU）/ mL，而蜂蜜中的孢子数仍保持在基线的1 log（10 ² CFU / mL）之内，但在蜂蜜中稳定增加。无毒品控制> 10 ⁵CFU / mL持续96 h。麦卢卡蜂蜜对艰难梭菌具有可变的抑制作用和杀菌活性。MGO等级对总体MIC分布或杀菌活性没有明显影响。尽管麦卢卡蜂蜜可以抑制孢子的增殖，但不能完全消除孢子。