Department of Endodontics and Molecular Microbiology Laboratory, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, RJ, Brazil.
Arch Oral Biol. 2013 Sep;58(9):1123-8. doi: 10.1016/j.archoralbio.2013.03.010. Epub 2013 Apr 13.
The purpose of this study was twofold: survey samples from acute and chronic endodontic infections for the presence of genes encoding resistance to beta-lactams, tetracycline and erythromycin, and evaluate the ability of treatment to eliminate these genes from root canals.
DNA extracts from samples of abscess aspirates (n=25) and root canals of teeth with asymptomatic apical periodontitis (n=24) were used as template for direct detection of the genes blaTEM, cfxA, tetM, tetQ, tetW, and ermC using real-time polymerase chain reaction (PCR). Bacterial presence was determined using PCR with universal bacterial primers. Root canals of the asymptomatic cases were also sampled and evaluated after chemomechanical procedures using NiTi instruments with 2.5% NaOCl irrigation.
All abscess and initial root canal samples were positive for bacteria. At least one of the target resistance genes was found in 36% of the abscess samples and 67% of the asymptomatic cases. The most prevalent genes in abscesses were blaTEM (24%) and ermC (24%), while tetM (42%) and tetW (29%) prevailed in asymptomatic cases. The blaTEM gene was significantly associated with acute cases (p=0.02). Conversely, tetM was significantly more prevalent in asymptomatic cases (p=0.008). Treatment eliminated resistance genes from most cases.
Acute and chronic endodontic infections harboured resistance genes for 3 classes of widely used antibiotics. In most cases, treatment was effective in eliminating these genes, but there were a few cases in which they persisted. The implications of persistence are unknown. Direct detection of resistance genes in abscesses may be a potential method for rapid diagnosis and establishment of proactive antimicrobial therapy.
本研究旨在调查急性和慢性根管感染样本中β-内酰胺类、四环素类和红霉素类耐药基因的存在情况，并评估治疗是否能从根管中消除这些基因。
采用实时聚合酶链反应（PCR），以脓肿抽吸物样本（n=25）和无根尖周炎症状的牙髓腔样本（n=24）的 DNA 提取物作为模板，直接检测 blaTEM、cfxA、tetM、tetQ、tetW 和 ermC 基因。采用通用细菌引物的 PCR 确定细菌的存在。对无症状病例的根管样本在使用 2.5%次氯酸钠冲洗的 NiTi 器械进行化学机械治疗后，也进行了采样和评估。
所有脓肿和初始根管样本均为细菌阳性。在 36%的脓肿样本和 67%的无症状病例中发现了至少一种目标耐药基因。在脓肿中最常见的基因是 blaTEM（24%）和 ermC（24%），而在无症状病例中，tetM（42%）和 tetW（29%）更为常见。blaTEM 基因与急性病例显著相关（p=0.02）。相反，tetM 在无症状病例中更为常见（p=0.008）。治疗从大多数病例中消除了耐药基因。
急性和慢性根管感染携带 3 类广泛使用抗生素的耐药基因。在大多数情况下，治疗能有效消除这些基因，但也有少数情况下它们持续存在。持续存在的影响尚不清楚。直接检测脓肿中的耐药基因可能是一种快速诊断和建立主动抗菌治疗的潜在方法。
