羧甲基壳聚糖对5株口腔颌面部感染细菌的抑菌性能的评价

目的 研究羧甲基壳聚糖对5株口腔颌面部感染细菌的抑菌性能,为在临床应用提供相关资料。方法 采用液体梯度稀释法分别测定羧甲基壳聚糖对牙龈卟啉菌、中间普氏菌、金黄色葡萄球菌、大肠埃希菌和铜绿假单胞菌的最低抑菌浓度（MIC）。结果 羧甲基壳聚糖对5株菌的MIC分别为：20、5、2.5、5、10 g/L。结论 羧甲基壳聚糖对口腔颌面部感染重要相关细菌具有抑菌作用。     

牙髓紫卟啉杆菌血清学特性分析

牙髓类杆菌曾是重要的产黑色素类杆菌群菌株,最近重新命名为牙髓紫卟啉杆菌,与牙髓尖周感染和牙源性脓肿有特殊关系。本文用牙髓紫卟啉杆菌ATCC 35406国际标准菌株免疫Balb/c小鼠制得免疫血清,ELISA法检测该抗血清的特异性。发现与中间型类杆菌、产黑色素类杆菌、赖氏类杆菌、躯体类杆菌、牙类杆菌、牙龈紫卟啉杆菌、脆弱类杆菌、黄褐二氧化碳嗜纤维菌、生痰二氧化碳嗜纤维菌、衣氏放线菌反应均阴性,而同不解糖紫卟啉杆菌呈现弱阳性反应,说明矛髓紫卟啉杆菌与不解糖紫卟啉杆菌具有某种相同抗原结构,存在血清交叉反应,血清学关系较近。牙髓紫卟啉杆茵多克隆抗体直接用于临床该菌的检出与鉴定,尚存一定缺陷。     

口臭症口腔微生态学的研究

目的 :研究口臭症患者口腔菌群分布。方法 :选择 3 0例口臭患者和 3 0例健康人 ,分别采集舌背舌苔和牙周袋菌斑作细菌的需氧、微需氧和厌氧菌的定量培养 ,并对牙龈卟啉单胞菌及衣氏放线菌做抑菌试验。结果 :口臭组舌背厌氧菌及微需氧菌总数 (12 .2± 1.3 2 )与健康对照组 (9.5± 1.2 4)差异有非常显著性 (P<0 .0 1) ,口臭组需氧菌总数与健康组差异有显著性 (P<0 .0 5) ;口臭组牙周袋厌氧菌及微需氧菌总数 (13 .12± 1.2 6)明显高于健康对照组 (11.3± 1.82 ) ,两者差异有非常显著性 (P<0 .0 1) ,而需氧菌差异无显著性 ;口臭症舌背以小韦荣菌为主 ,其次是黑色普氏菌 ;牙周袋菌斑以牙龈卟啉单胞菌和黑色普氏菌为主 ,其次是衣氏放线菌。并筛选出两类抗菌漱口水和一种中外合资抗口臭牙膏 ,对舌背及牙周袋菌斑的主要细菌牙龈卟啉单胞菌和衣氏放线菌有明显的抑制作用。结论 :口臭症患者口腔菌群分布和总数与正常人群存在显著的差异 ,与牙周病有关的致病菌数量明显高于正常人群 ,据抑菌试验结果采用有效的漱口液及牙膏可明显降低口腔内致病菌和改善口臭症状。     

儿童乳牙根尖周炎感染根管厌氧细菌学分析

目的：报告50例5-8.5岁儿童根尖周炎患者感染根管73颗乳牙厌氧菌分离鉴定及体外药敏试验的结果,方法：采用K-B法。结果：89.04%(65/73)的患牙共检出厌氧菌150株,平均每例标本检出2.3株,常用抗厌氧菌药物替硝唑（TNZ）、甲硝唑（MNZ）对革兰阴性厌氧菌（产黑色素普氏菌,中间普氏菌,解脲拟杆菌,具核梭杆菌,牙龈二氧化碳噬纤维菌）有较好的抑菌作用;林可霉素对革兰阳性厌氧菌（厌氧消化链球菌,嗜酸乳杆菌）的作用则强于TNZ和MNZ,氯霉素（C）和乙旋螺旋霉素（AS）抗厌氧菌的作用则弱于前三者。结论：分析儿童乳牙根尖周炎感染根管菌群来决定抗菌药物的选择,在临床治疗上是必要的。     

不同妊娠状态下女性口腔微生物的结构差异性

【背景】妊娠期妇女口腔微生物改变与口腔疾病及全身性疾病之间有显著相关性。【目的】比较不同妊娠状态下女性口腔微生物结构的差异,探讨该差异与不同妊娠状态间的关联性。【方法】选取18名孕妇和9名非孕妇为研究对象[（28.2±3）岁],分为妊娠期糖尿病组[gestational diabetes mellitus,GDM,年龄（28.9±3.6）岁,孕周（30.1±3.2）周]、妊娠期非糖尿病组[non-diabetic pregnant women,PW,年龄（27.9±3.0）岁,孕周（28.6±4.7）周]和非妊娠期非糖尿病组[non-pregnant women,NPW,年龄（27.7±2.1）岁],每组9名,收集口腔唾液（saliva,S）和龈上牙菌斑（supragingival dental plaque,D）,采取Illumina Novaseq测序平台针对细菌16S rRNA基因的V3-V4可变区进行测序,以SILVA为参考数据库使用朴素贝叶斯分类器对特征序列进行分类学注释,利用QIIME软件对样本进行生物信息学分析。【结果】三组中唾液及牙菌斑微生物差异比较显示：D-GDM中二氧化碳嗜纤维菌属检出量高于D-PW,而月形单胞菌属检出量显著低于D-PW;S-GDM中产气单胞菌属、拟杆菌属等厌氧菌属检出量高于S-PW,韦荣氏菌属检出量低于S-PW;D-PW中纤毛菌属、普氏菌属和月形单胞菌属检出量显著高于D-NPW;D-NPW中产气单胞菌属、放线杆菌属、二氧化碳嗜纤维杆菌属、奈瑟菌属、链球菌属和劳特罗氏菌属等检出量高于D-PW;S-PW中韦荣菌属、普氏菌属、链球菌属和卟啉单胞菌属检出量低于S-NPW;D-GDM中福赛斯坦纳菌属、纤毛菌属检出量高于D-NPW,劳特罗氏菌属检出量低于D-NPW;S-GDM中密螺旋体属、弯曲杆菌属检出量高于S-NPW,链球菌属低于S-NPW。在种水平上,S-GDM菌群中具核梭杆菌检出量显著高于S-PW,S-GDM菌群中牙龈卟啉单胞菌及福赛斯坦纳菌检出量与S-PW差异无统计学意义,产黑普氏菌检出量低于S-PW;S-PW中牙龈卟啉单胞菌、产黑普氏菌和福赛斯坦纳菌检出量均显著高于S-NPW。【结论】孕妇妊娠期糖尿病将增加口腔微生物群厌氧菌检出率,GDM与牙龈卟啉单胞菌、福赛斯坦纳菌和产黑普氏菌等牙周炎致病菌相关性不能确定。     

血液链球菌对牙周可疑致病菌的拮抗作用

本实验观察了血液链球菌对与牙周组织破坏关系密切的５种细菌的拮抗作用,包括：放线共生放线杆菌、牙龈类杆菌１中间类杆菌,产黑色素类杆菌、具核梭杆菌、二氧化碳噬纤维菌和放线菌。结果表明,在体外,血液链球菌除对粘性放线菌无拮抗作用外,对所有参试的这几种牙周可疑致病菌均有拮抗作用。拮抗物质存在于血液链球菌生活的细胞内。     

甘草提取物对四种牙周常见致病菌的抑菌作用

目的体外评价甘草提取物对牙龈卟啉单胞菌、中间普氏菌、具核梭杆菌和伴放线放线杆菌四种牙周常见致病菌的抑制效果。方法以牙龈卟啉单胞菌、中间普氏菌、具核梭杆菌和伴放线放线杆菌四种牙周常见致病菌作为供试菌,采用液体稀释法,考察甘草提取物对这四种细菌的最小抑菌浓度(MIC)和最小杀菌浓度(MBC);并采用不同浓度的甘草提取物溶液,绘制甘草提取物对四种牙周致病菌的时间-杀菌曲线。结果甘草提取物对牙龈卟啉单胞菌、中间普氏菌、具核梭杆菌和伴放线放线杆菌的MIC值分别为1.50、1.50、0.75和1.50mg/mL,MBC值分别为6、3、3和3mg/mL。当甘草提取物达到对四种细菌的MBC值时,对于牙龈卟啉单胞菌、中间普氏菌、伴放线放线杆菌可在2h后可达到杀菌效果,对于具核梭杆菌可在4h后达到杀菌效果。结论甘草提取物对以上四种牙周常见致病菌具有良好的抑菌及杀菌作用。     

成人牙周炎龈下套氧菌分离鉴定及药敏试验结果分析

分离并鉴定了329例成人牙周炎龈下优势厌氧菌群,并对不同病程中的菌群变迁、厌氧菌的药物敏感性进行了分析.成人牙周炎龈下标本中厌氧菌阳性检出率为97.9%,其中以牙龈紫质单胞菌检出率最高(38.5%),具核梭杆菌次之(18.9%).随着牙周病变程度的加重,牙龈紫质单胞菌、具核梭杆菌、产黑色素普氏菌、星群厌氧链球菌、厌氧消化链球菌的检出率增高(P＜0.05),小韦荣球菌的检出率下降(P＜0.01),表明前5种厌氧菌在AP发病过程中有重要作用,小韦荣球菌与之无关.替硝唑、甲硝唑和克林霉素对438株革兰氏阴性厌氧菌的MIC90分别为1～8,2～8和4～16 mg/L,对278株革兰氏阳性厌氧菌的MIC90分别为16～32,16～64和4～16 mg/L,表明替硝唑和甲硝唑体外抗革兰氏阴性厌氧菌效果优于克林霉素,抗革兰氏阳性厌氧菌作用不如克林霉素.     

血链球菌在不同牙周状态下的分布及相关研究

目的：探讨口腔主要过氧化氢产生菌血链球菌和口腔链球菌在不同牙周健康状态下龈下菌群中的分布,及与牙周健康状态和牙龈卟啉单胞菌群中分布的相互关系。方法：纳入符合标准的受试者30人,受试位点86个,其中健康组11人,位点30个,龈炎组9人,位点29个,慢性牙周炎组10人,位点27个,检查记录牙周健康状态[包括牙龈指数（GI）和牙周袋深度（PD）],采集龈下菌斑标本,经厌氧菌培养基和AP-PCR及PCR鉴定后,将各受试组进行比较分析。结果：共获得草绿色链球菌523株,产黑色素菌241株。经AP-PCR及PCR鉴定后,得到血链球菌112株,口腔链球菌56株,牙龈卟啉单胞菌84株,健康组龈下菌斑中血链球菌,口腔链球菌和牙龈卟啉单胞菌构成比与牙周炎组相比有差异显著性;血链球菌和口腔链球菌与GI、PD呈负相关,牙龈卟啉菌与GI、PD呈正相关;血链球菌的构成与牙龈卟啉单胞菌的构成比呈负相关。结论：血链球菌等过氧化氢产生菌在龈下菌斑中比例的下降。可能是微生态失衡,致病菌过度增殖的重要机制。     

247例颌面部感染的细菌学研究

采用需氧和厌氧培养方法,分离培养２４７例颌面部感染标本的细菌。结果表明口腔颌面部感染以牙源性颌面部感染最多见,其感染率为８７９％。颌面部感染的细菌学特点是：①厌氧菌感染为主,其感染率在牙源性感染为９６％,非牙源性感染为７３７％,可培养的优势厌氧菌是普氏菌、叶啉单胞菌、梭杆菌、消化链球菌,其次是放线菌、优杆菌和二氧化碳噬纤维菌、口腔链球菌群细菌是主要的兼性厌氧菌,其次是嗜血菌。②由定植于口腔的细菌引发的内源性感染。③复数菌和混合菌感染为主     

Oral streptococcal glyceraldehyde-3-phosphate dehydrogenase mediates interaction with Porphyromonas gingivalis fimbriae

Interaction of Porphyromonas gingivalis with plaque-forming bacteria is necessary for its colonization in periodontal pockets. Participation of Streptococcus oralis glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and P. gingivalis fimbriae in this interaction has been reported. In this investigation, the contribution of various oral streptococcal GAPDHs to interaction with P. gingivalis fimbriae was examined. Streptococcal cell surface GAPDH activity was measured by incubation of a constant number of streptococci with glyceraldehyde-3-phosphate and analysis for the conversion of NAD+ to NADH based on the absorbance at 340 nm. Coaggregation activity was measured by a turbidimetric assay. Cell surface GAPDH activity was correlated with coaggregation activity (r = 0.854, P < 0.01) with Spearman's rank correlation coefficient. S. oralis ATCC 9811 and ATCC 10557, Streptococcus gordonii G9B, Streptococcus sanguinis ATCC 10556, and Streptococcus parasanguinis ATCC 15909 exhibited high cell surface GAPDH activity and coaggregation activity; consequently, their cell surface GAPDHs were extracted with mutanolysin and purified on a Cibacron Blue Sepharose column. Subsequently, their DNA sequences were elucidated. Purified GAPDHs bound P. gingivalis recombinant fimbrillin by Western blot assay, furthermore, their DNA sequences displayed a high degree of homology with one another. Moreover, S. oralis recombinant GAPDH inhibited coaggregation between P. gingivalis and the aforementioned five streptococcal strains in a dose-dependent manner. These results suggest that GAPDHs of various plaque-forming streptococci may be involved in their attachment to P. gingivalis fimbriae and that they may contribute to P. gingivalis colonization.     

Black-pigmented Gram-negative anaerobes in endodontic infections

Abstract Necrotic dental root canal infections are polymicrobial infections dominated by anaerobic bacteria. The number of different species in one canal is usually low, approx. 4–7 species. The species isolated most frequently belong to the genera Prevotella, Porphyromonas, Fusobacterium, Peptostreptococcus, Eubacterium and Streptococcus . The frequency of isolation of black-pigmented Gram-negative anaerobes in endodontic infections varies from 25% to >50%. Pr. intermedia is the most commonly found pigmented species, followed by Pr. denticola and two Porphyromonas species, P. gingivalis and P. endodontalis . Several studies have shown that P. gingivalis and P. endodontalis are closely related to the presence of acute symptoms in endodontic infections, whereas other black-pigmented Gram-negative anaerobes are not. However, several other species may also be involved in acute infections. Moreover, Porphyromonas species have occasionally been isolated from cases with no symptoms. Although Porphyromonas spp. are clearly related to symptoms at the beginning of therapy, they are not important for the prognosis of the treatment.     

Expression of saliva-binding epitopes of the Porphyromonas gingivalis FimA protein on the surface of Streptococcus gordonii

Porphyromonas gingivalis, a gram-negative oral anaerobic bacterium, has been implicated in the onset and development of periodontitis. The P. gingivalis fimbriae which mediate bacterial adherence to host oral sites and induce host inflammatory responses have been suggested as a potential antigen candidate. for vaccine development. This study was undertaken to generate Streptococcus gordonii vectors expressing the major subunit protein (FimA) of P. gingivalis fimbriae for testing as a potential live vaccine against periodontitis. We report here the expression of the C-terminal saliva-binding epitopes of P. gingivalis FimA on the surface of S. gordonii and demonstrate that domains containing free cysteine residues are poorly expressed on the surface of S. gordonii.     

Porphyromonas gingivalis prevalence related to other micro-organisms in adult refractory periodontitis.

Forty-six adult periodontal patients, selected on the basis of clinical examination, and 46 adult healthy subjects were examined. The subgingival plaque samples from one inflammatory and one non-inflammatory site of each periodontal patient were studied to determine Porphyromonas gingivalis prevalence related to other periodontal micro-organisms and to periodontal tissue destruction. The results showed Porphyromonas gingivalis as the main pathogenic micro-organism isolated in the inflammatory sites together with Bacteroides forsythus. Peptostreptococcus sp., Actinomyces sp. and Prevotella sp. were found as a normal oral flora in the healthy subjects. Fusobacterium nucleatum, Prevotella intermedia, Campylobacter rectus and Eikenella corrodens were detected both in inflammatory and in non-inflammatory sites of periodontal patients as well as in the healthy subjects.     

Susceptibility of Prevotella intermedia/Prevotella nigrescens (and Porphyromonas gingivalis) to propolis (bee glue) and other antimicrobial agents

Black-pigmented gram-negative anaerobes such as Porphyromonas gingivalis and Prevotella intermedia are suspected pathogens in adult periodontitis, whereas Prevotella nigrescens has been associated with health. Antimicrobial resistance among bacteria from this group has been reported in the past decade. This research aimed to evaluate and compare the susceptibility profile of 17 P. intermedia/P. nigrescens isolates recovered from patients with periodontitis and three reference strains to six antimicrobials, prescribed in dentistry in Brazil, and propolis (bee glue). The antimicrobial agents tested were tetracycline, penicillin, clindamycin, erythromycin, metronidazole, meropenem and six ethanolic extracts of propolis (EEPs) from Brazil. The reference strains P. gingivalis ATCC 33277 and P. intermedia ATCC 25611 were used for determination of minimum bactericidal concentration (MBC) and for time-kill assay to the EEPs. All of the strains were susceptible to penicillin, erythromycin, meropenem, metronidazole and 95% of them (n=19) to tetracycline. Thirty six percent (n=7) of the P. intermedia/P. nigrescens strains tested were resistant to clindamycin. As for propolis activity, all strains were susceptible and the minimum inhibitory concentration values ranged from 64 to 256 microg/mL. For the reference strains P. gingivalis ATCC 33277 and Prevotella intermedia ATCC 25611 the MBC was 256 microg/mL and death was observed within 3 h of incubation for P. gingivalis and within 6 h for P. intermedia. The action of propolis (bee glue) against suspected periodontal pathogens suggests that it may be of clinical value.     

Expression of the short fimbriae of Porphyromonas gingivalis is regulated in oral bacterial consortia

The Mfa1 protein of Porphyromonas gingivalis is the structural subunit of the short fimbriae and mediates coadhesion between P. gingivalis and Streptococcus gordonii. We utilized a promoter-lacZ reporter construct to examine the regulation of mfa1 expression in consortia with common oral plaque bacteria. Promoter activity of mfa1 was inhibited by S. gordonii, Streptococcus sanguinis and Streptococcus mitis. In contrast, Streptococcus mutans, Streptococcus cristatus, Actinomyces naeslundii, Actinobacillus actinomycetemcomitans and Fusobacterium nucleatum did not affect mfa1 expression. Expression of SspA/B, the streptococcal receptor for Mfa1, was not required for regulation of mfa1 promoter activity. Proteinaceous molecule(s) in oral streptococci may be responsible for regulation of Mfa1 expression. Porphyromonas gingivalis is capable of detecting heterologous organisms, and responds to selected organisms by specific gene regulation.     

牙菌斑链球菌与牙龈卟啉单胞菌相互作用的研究

牙菌斑生物膜是牙周病最主要的致病因素。早期定植菌链球菌与晚期定植菌牙龈卟啉单胞菌(P.gingivalis)的相互作用复杂多样,而牙龈卟啉单胞菌是重要的牙周致病菌,本文就链球菌与牙龈卟啉单胞菌的相互作用作一综述。     

Characterization of a bacteriocin produced by Prevotella nigrescens ATCC 25261

AIMS: To characterize the antimicrobial activity produced by Prevotella nigrescens ATCC 25261, and to evaluate its safety on cultured gingival fibroblasts. METHODS AND RESULTS: An antimicrobial activity was obtained from purifying the culture supernatant of Pr. nigrescens ATCC 25261. Purification of the active compound was achieved with ammonium sulphate precipitation followed by anion-exchange and gel filtration chromatography. As revealed by SDS-PAGE, the active fraction was relatively homogeneous, showing a protein with an approximate molecular weight of 41 kDa. The antimicrobial compound, named nigrescin, exhibited a bactericidal mode of action against Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, and Actinomyces spp. Nigrescin was stable in a pH range between 6.5 and 9.5, at 100 degrees C for 10 min, and resistant to lyophilization. But its activity was lost after proteinase K treatment. Despite at very high concentrations beyond the minimum inhibitory concentration (MIC), nigrescin was not toxic to the gingival fibroblasts. CONCLUSION: Nigrescin is a novel bacteriocin produced by Pr. nigrescens ATCC 25261. It exhibits antimicrobial activity against species that are implicated in periodontal diseases. The absence of toxicity on the gingival fibroblasts suggests the possibility in using of nigrescin for an application in periodontal treatment. SIGNIFICANCE AND IMPACT OF THE STUDY: Novel evidence on nigrescin would make Pr. nigrescens ATCC 25261 attractive in biotechnological applications as an antimicrobial agent in clinical dentistry.