Berlutti Francesca, Frioni Alessandra, Natalizi Tiziana, Pantanella Fabrizio, Valenti Piera
Department of Public Health and Infectious Diseases, University Sapienza of Rome, Rome, Italy.
J Antibiot (Tokyo). 2014 Nov;67(11):763-9. doi: 10.1038/ja.2014.66. Epub 2014 May 28.
Staphylococcus biofilm exhibits high antibiotic resistance and therapeutic doses of antibiotics are often sub-inhibitory. Whereas data are available on the effect of sub-inhibitory antibiotics on matrix formation, little is known on their influence on biofilm population. Here, using BioTimer Assay (BTA), a method developed to quantify biofilm population, the influence of sub-inhibitory gentamicin, ofloxacin and azithromycin on Staphylococcus aureus ATCC 6538 biofilm population in flow with respect to static condition was assessed. Antibiotics and flow condition increased biofilm population even if at different extent, depending on the antibiotic molecule. The greatest bacterial population was found in biofilm developed under flow condition in the presence of azithromycin. A significant increase in biofilm matrix was recorded for biofilm developed in the presence of antibiotics in flow with respect to static condition. The growth rates (GRs) of 24-h biofilm developed under the influence of antibiotics and flow condition were also evaluated using BTA and a specific mathematical model. Antibiotics and flow condition affected the GRs of 24-h biofilm even if at different extent. The lowest GR value was recorded for biofilm developed under flow condition in the presence of ofloxacin. Although further studies are needed, our data indicate that antibiotics and flow condition influenced biofilm development by increasing both bacterial population and matrix formation and affected the GRs of the developed biofilm. To the best of our knowledge, BTA is unique in allowing the calculation of the GRs of biofilm and it may be considered to be a useful study model to evaluate the activity of antibiofilm molecules.
葡萄球菌生物膜表现出高度的抗生素耐药性，抗生素的治疗剂量往往处于亚抑菌水平。虽然已有关于亚抑菌浓度抗生素对生物膜基质形成影响的数据，但对于它们对生物膜群体的影响却知之甚少。在此，我们使用生物定时器测定法（BTA）（一种用于量化生物膜群体的方法），评估了亚抑菌浓度的庆大霉素、氧氟沙星和阿奇霉素在流动条件下相对于静态条件对金黄色葡萄球菌ATCC 6538生物膜群体的影响。抗生素和流动条件即使程度不同，也会增加生物膜群体，这取决于抗生素分子。在流动条件下且存在阿奇霉素时形成的生物膜中发现了最大的细菌群体。与静态条件相比，在流动条件下且存在抗生素时形成的生物膜记录到生物膜基质有显著增加。还使用BTA和一个特定的数学模型评估了在抗生素和流动条件影响下形成的24小时生物膜的生长速率（GRs）。抗生素和流动条件即使程度不同，也会影响24小时生物膜的GRs。在流动条件下且存在氧氟沙星时形成的生物膜记录到最低的GR值。尽管还需要进一步研究，但我们的数据表明，抗生素和流动条件通过增加细菌群体和基质形成来影响生物膜的形成，并影响已形成生物膜的GRs。据我们所知，BTA在允许计算生物膜的GRs方面是独一无二的，它可被认为是评估抗生物膜分子活性的一个有用的研究模型。
