Biofilmzentrum, Dept. of Microbiology, Infectious Disease and Immunology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
MoKi Analytics GmbH, Marienplatz, Berlin, Germany.
PLoS One. 2020 Apr 23;15(4):e0231827. doi: 10.1371/journal.pone.0231827. eCollection 2020.
The diagnosis of infective endocarditis (IE) remains a challenge. One of the rare bacterial species recently associated with biofilms and negative cultures in infective endocarditis is Aerococcus urinae. Whether the low number of reported cases might be due to lack of awareness and misidentification, mainly as streptococci, is currently being discussed. To verify the relevance and biofilm potential of Aerococcus in endocarditis, we used fluorescence in situ hybridization to visualize the microorganisms within the heart valve tissue. We designed and optimized a specific FISH probe (AURI) for in situ visualization and identification of A. urinae in sections of heart valves from two IE patients whose 16S rRNA gene sequencing had deteced A. urinae. Both patients had a history of urinary tract infections. FISH visualized impressive in vivo grown biofilms in IE, thus confirming the potential of A. urinae as a biofilm pathogen. In both cases, FISH/PCR was the only method to unequivocally identify A. urinae as the only causative pathogen for IE. The specific FISH assay for A. urinae is now available for further application in research and diagnostics. A. urinae should be considered in endocarditis patients with a history of urinary tract infections. These findings support the biofilm potential of A. urinae as a virulence factor and are meant to raise the awareness of this pathogen.
感染性心内膜炎（IE）的诊断仍然具有挑战性。最近与生物膜和感染性心内膜炎中的阴性培养相关的一种罕见细菌物种是解脲尿球菌。目前正在讨论报告的病例数量较少是否是由于缺乏认识和错误识别，主要是被误识别为链球菌。为了验证解脲尿球菌在心内膜炎中的相关性和生物膜潜力，我们使用荧光原位杂交技术可视化心脏瓣膜组织中的微生物。我们设计并优化了一种特定的 FISH 探针（AURI），用于原位可视化和鉴定来自两名 IE 患者心脏瓣膜切片中的 A. urinae，这两名患者的 16S rRNA 基因测序均检测到解脲尿球菌。这两名患者均有尿路感染史。FISH 在 IE 中可视化了令人印象深刻的体内生长的生物膜，从而证实了解脲尿球菌作为生物膜病原体的潜力。在这两种情况下，FISH/PCR 是唯一能够明确鉴定解脲尿球菌为 IE 唯一致病病原体的方法。用于鉴定解脲尿球菌的特定 FISH 检测方法现已可用于进一步的研究和诊断应用。对于有尿路感染史的 IE 患者，应考虑解脲尿球菌。这些发现支持解脲尿球菌作为毒力因子的生物膜潜力，并旨在提高对这种病原体的认识。
