Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
Embrapa Gado de Leite, Juiz de Fora, MG, Brazil.
J Dairy Res. 2021 May;88(2):179-184. doi: 10.1017/S0022029921000285. Epub 2021 May 17.
Biofilm formation is a central feature to guarantee staphylococcal persistence in hosts and is associated with several diseases that are difficult to treat. In this research paper, biofilm formation and antimicrobial susceptibility were investigated in staphylococcal strains belonging to several species. These strains were isolated from the milk of cows with subclinical mastitis and most of them were coagulase-negative, with the prevalence of Staphylococcus chromogenes. High genetic diversity was observed among the strains by pulsed field gel electrophoresis. Antimicrobial resistance was assessed by disk diffusion and more than 50% of the strains were resistant to ampicillin and penicillin G, with multi-resistance profiles (13.6%) also being observed. Most strains (65.9%) formed biofilms when cultivated in BHI supplemented with 1% glucose. Most strains (72.7%) carried the intercellular adhesion gene (icaA), while less than half (36.3%) carried the biofilm-associated protein gene (bap). Concentrations of up to 10xMIC of erythromycin and tetracycline were not sufficient to suppress cell viability in preformed biofilms. Our results revealed that a genetically diverse group of biofilm-forming Staphylococcus species can be involved in subclinical mastitis. Since high antimicrobial concentrations cannot eradicate biofilm cells in vitro, their use in dairy animals may be ineffective in controlling infections, while supporting selection of resistant microorganisms. These data reinforce the need for alternative therapies aiming at disrupting biofilms for effective disease control.
生物膜形成是保证葡萄球菌在宿主中持续存在的核心特征，与许多难以治疗的疾病有关。在这项研究中，研究了属于几种物种的葡萄球菌菌株的生物膜形成和抗菌药物敏感性。这些菌株是从患有亚临床乳腺炎的奶牛的牛奶中分离出来的，其中大多数为凝固酶阴性菌，以产色葡萄球菌为主。脉冲场凝胶电泳显示，这些菌株具有高度的遗传多样性。通过圆盘扩散法评估了抗菌药物耐药性，超过 50%的菌株对氨苄西林和青霉素 G 耐药，还观察到多耐药谱（13.6%）。当在添加 1%葡萄糖的 BHI 中培养时，大多数菌株（65.9%）形成生物膜。大多数菌株（72.7%）携带细胞间黏附基因（icaA），而不到一半（36.3%）携带生物膜相关蛋白基因（bap）。高达 10 倍 MIC 的红霉素和四环素浓度不足以抑制已形成生物膜的细胞活力。我们的结果表明，一组遗传多样性的形成生物膜的葡萄球菌物种可能与亚临床乳腺炎有关。由于高浓度的抗菌药物不能在体外消除生物膜细胞，因此在奶牛中使用这些药物可能无法有效控制感染，同时支持耐药微生物的选择。这些数据强调了需要寻找替代疗法来破坏生物膜，以有效控制疾病。
