Study on novel drug-resistant bacteria in oral biofilms and the resistance mechanisms

假单胞菌、不动杆菌和结核分枝杆菌耐多药的持续出现是一个全球性的健康问题。最近，Dantas G博士等人报告说，他们分离出的数百种土壤细菌有能力以抗生素作为唯一的碳源生长。许多依赖抗生素生存的细菌与人类病原体密切相关。本研究的目的是调查多重耐药细菌和以抗生素为生的细菌在牙菌斑和牙单位水管等牙环境中的分布情况。能够在青霉素和卡那霉素上生长的代表性分离株是从牙科单位水系中分离出来的。通过16S核糖体RNA基因测序分析，分别鉴定为水栖鞘氨单胞菌和食几丁菌。健康受试者和牙周炎患者均未检出耐多药细菌和依赖抗生素生存的细菌。然而，从长期接受全身抗生素治疗的严重细菌感染（败血症）患者口腔中分离出耐药粪肠球菌、耐甲氧西林表皮葡萄球菌和β-内酰胺耐药口服链球菌。牙菌斑通过全身抗生素治疗可改变菌斑的组成，使耐药菌富集，以抗生素为生的细菌也存在于牙科临床环境中。

The continuing emergence of multi-drug resistance in Pseudomonas, Acinetobacter, and Mycobacterium tuberculosisis a global health problem. Recently Dr. Dantas G et al. reported that their isolated hundreds of soil bacteria had the capacity to grow on antibiotics as a sole carbon source. Many bacteria subsisting on antibiotics were closely related to human pathogens. The aim of this study was to investigate the distribution of the multi-drug resistant bacteria and bacteria subsisting on antibiotics in dental plaques and dental environments such as dental unit water lines. Representative isolates capable of growth on penicillin and kanamycin were isolated from Dental unit water lines. They were identified Sphingomonas aquatilisa n d Chitinophaga sp. by 16S ribosomal RNA gene sequencing analysis. No multi-drug resistant bacteria and bacteria subsisting on antibiotics were detected in any of the samples from healthy subjects and patients with periodontitis. However, drug resistant Enterococcus faecalis, methicillin resistant Staphylococcus epidermidis and β-lactam antibiotics resistant oral Streptococci were isolated from the oral cavity of a patient with long-term systemic antibiotic therapy for severe bacterial infection(septis). Dental plaques may alter their composition and enrich for bacteria resistant to antibiotics by systemic antibiotic therapy and bacteria subsisting on antibiotics have been also present in dental clinic environment.