Mezzasalma Nicolò, Spadini Costanza, Spaggiari Chiara, Annunziato Giannamaria, Andreoli Valentina, Prosperi Alice, Mochen Lorenzo, Cavirani Sandro, Grolli Stefano, Taddei Simone, Costantino Gabriele, Cabassi Clotilde Silvia
Department of Veterinary Science, University of Parma, Parma, Italy.
Department of Food and Drug, University of Parma, Parma, Italy.
Front Vet Sci. 2025 May 14;12:1565787. doi: 10.3389/fvets.2025.1565787. eCollection 2025.
Antibiotics represent the first line therapy for bovine mastitis. However, the increasing prevalence of multidrug-resistant organisms (MDROs) highlights the need for alternative therapeutic approaches. This study evaluated the antimicrobial and antibiofilm activities of leaf extract (EGL-L), ursolic acid (UA) and asiatic acid (AA) against (SA), (SU), (SAG), and spp. (EN) isolated from bovine mastitis, 39.7% of which were MDROs. The minimal inhibitory concentration (MIC) assay demonstrated that all the compounds exhibited antimicrobial activity against the tested bacteria, including MDROs. However, EGL-L was less effective ( < 0.001) than UA or AA against field strains. UA was more effective against SAG and SU compared to SA ( < 0.001), whereas AA was more effective against SU than SA ( < 0.001). Conversely, EGL-L exhibited similar inhibitory effects on all bacteria. The biofilm-forming ability of the bacterial strains was also assessed, and the minimal biofilm inhibitory concentrations (MBICs) of the compounds were evaluated for moderate and strong biofilm producers. None of the compounds were able to completely inhibit biofilm formation. However, MBIC values within the tested concentration range were achieved for 15 out of 32 strains with EGL-L and for 27 out of 32 strains with UA and AA. These findings highlight a promising alternative to conventional antimicrobials for AA and UA, showing potential for topical intramammary use for the control and prevention of bovine mastitis, especially because of their efficacy against biofilm formation. Future research should focus on toxicity assessments and formulation development for potential topical administration.
抗生素是治疗牛乳腺炎的一线疗法。然而，多重耐药菌（MDROs）的日益流行凸显了采用替代治疗方法的必要性。本研究评估了叶提取物（EGL-L）、熊果酸（UA）和积雪草苷（AA）对从牛乳腺炎中分离出的金黄色葡萄球菌（SA）、停乳链球菌（SU）、无乳链球菌（SAG）和肠球菌属（EN）的抗菌和抗生物膜活性，其中39.7%为多重耐药菌。最低抑菌浓度（MIC）试验表明，所有化合物对受试细菌（包括多重耐药菌）均表现出抗菌活性。然而，EGL-L对田间菌株的效果不如UA或AA（P<0.001）。与SA相比，UA对SAG和SU更有效（P<0.001），而AA对SU比对SA更有效（P<0.001）。相反，EGL-L对所有细菌表现出相似的抑制作用。还评估了细菌菌株的生物膜形成能力，并针对中度和强生物膜产生菌评估了化合物的最低生物膜抑制浓度（MBIC）。没有一种化合物能够完全抑制生物膜形成。然而，在测试浓度范围内，EGL-L使32株菌株中的15株达到了MBIC值，UA和AA使32株菌株中的27株达到了MBIC值。这些发现突出了AA和UA作为传统抗菌剂的一种有前景的替代品，显示出局部乳房内使用以控制和预防牛乳腺炎的潜力，特别是因为它们对生物膜形成的功效。未来的研究应侧重于潜在局部给药的毒性评估和制剂开发。
