Melchior M B, Fink-Gremmels J, Gaastra W
Department of Veterinary Pharmacy and Toxicology, Faculty of Veterinary Medicine, University of Utrecht, 3508 TD, Utrecht, The Netherlands.
Vet Microbiol. 2007 Nov 15;125(1-2):141-9. doi: 10.1016/j.vetmic.2007.05.019. Epub 2007 May 31.
Staphylococcus aureus is one of the most prevalent causes of bovine mastitis. The antimicrobial treatment of this disease is currently based on antimicrobial susceptibility tests according to CLSI standards. However, various studies have shown that there is a discrepancy between the results of this standard susceptibility test and the actual cure rate of the applied antimicrobial treatment. Increasing evidence suggests that biofilm formation by S. aureus is associated with this problem. The currently available antimicrobial susceptibility assays for bacteria growing in biofilms, are not considered reliable enough for routine application. Therefore, the objective of this study was to further develop a susceptibility test for bacteria growing in biofilm, suitable for routine testing of the antimicrobial susceptibility of S. aureus. With the expansion of the available MBEC assay to an extended biofilm susceptibility test, that comprises 2 and 4 consecutive days of antimicrobial challenge, the antimicrobial susceptibility for S. aureus growing in biofilm was further analysed. The results showed clear differences between strains and various antimicrobial agents with respect to the effect of longer duration of the antimicrobial challenge on the eradication of S. aureus growing in biofilm. The extended biofilm susceptibility test also indicates that each bacterial strain requires a specific duration of antimicrobial therapy, which cannot be derived from a standard susceptibility test or from a 24-h biofilm susceptibility test.
金黄色葡萄球菌是引起牛乳腺炎最常见的病因之一。目前，针对该疾病的抗菌治疗是基于依据临床和实验室标准协会（CLSI）标准进行的药敏试验。然而，多项研究表明，这种标准药敏试验的结果与所应用抗菌治疗的实际治愈率之间存在差异。越来越多的证据表明，金黄色葡萄球菌形成生物膜与这一问题有关。目前用于检测生物膜中细菌的药敏试验方法，其可靠性还不足以用于常规应用。因此，本研究的目的是进一步开发一种适用于生物膜中细菌的药敏试验，以用于金黄色葡萄球菌药敏性的常规检测。随着可用的最低生物被膜消除浓度（MBEC）试验扩展为一种延长的生物膜药敏试验，该试验包括连续2天和4天的抗菌挑战，对生物膜中生长的金黄色葡萄球菌的药敏性进行了进一步分析。结果表明，就延长抗菌挑战时间对生物膜中生长的金黄色葡萄球菌的根除效果而言，不同菌株和各种抗菌剂之间存在明显差异。延长的生物膜药敏试验还表明，每种细菌菌株都需要特定时长的抗菌治疗，这无法从标准药敏试验或24小时生物膜药敏试验中得出。
