This study examined the use of phage therapy against Pseudomonas aeruginosa strain PA14 biofilms. Part 1: 24 and 96h PA14 biofilms grown in microplates were phage treated and bacterial biomass was quantified using crystal violet staining. Part 2: 24 and 96h PA14 biofilms grown in prepared root canals of human mandibular incisors were treated with phages and intra-canal samples using paper points and round burs were taken to assess phage and bacterial counts. Part 1: Two phages (JBD4 and JBD44a) were used. Treatment with phages produced significant reduction in the mean percentage of biomass in 24h (p<0.05) and 96h (p=0.08) biofilms. Part 2: In 24 and 96h biofilms in a root canal model, no significant difference was found in colony forming units after phage treatment (p>0.05). Phage application significantly reduced the biomass of 24 and 96h PA14 biofilms grown on microplates, but did not in the extracted tooth models.

This study examined the use of phage therapy against Pseudomonas aeruginosa strain PA14 biofilms. Part 1: 24 and 96h PA14 biofilms grown in microplates were phage treated and bacterial biomass was quantified using crystal violet staining. Part 2: 24 and 96h PA14 biofilms grown in prepared root canals of human mandibular incisors were treated with phages and intra-canal samples using paper points and round burs were taken to assess phage and bacterial counts. Part 1: Two phages (JBD4 and JBD44a) were used. Treatment with phages produced significant reduction in the mean percentage of biomass in 24h (p<0.05) and 96h (p=0.08) biofilms. Part 2: In 24 and 96h biofilms in a root canal model, no significant difference was found in colony forming units after phage treatment (p>0.05). Phage application significantly reduced the biomass of 24 and 96h PA14 biofilms grown on microplates, but did not in the extracted tooth models.

Background: In this study, we enhanced a diagnostic questionnaire which had been previously developed to measure stress and social support. Methods: 101 patients with chronic periodontitis and 50 healthy control subjects completed our questionnaire package after which we analyzed the data for trends and associations. Results: Our enhanced questionnaire provided a valid and reliable measure of stress and social support in patients with chronic periodontitis. Conclusion: Our enhanced questionnaire provided both a valid and a reliable measure of stress and social support in patients with chronic periodontitis however requires further refinement to predict periodontal disease experience and severity.

Background and Objective: A relationship between some systemic diseases and periodontitis has been described. Several studies have reported a link between periodontal disease and atherosclerosis. This study aimed (i) to support the link between the two diseases by evaluating the statistically significant simultaneous detection of five putative periodontopathogens (A.actynomicetemcomitans, P.intermedia, T.forsythia, F.nucleatum and P.gingivalis) in periodontal pockets and carotid atheromatous plaques, and (ii) to analyze the risk factors associated to atherosclerosis and/or periodontitis in the study population.Materials and Methods: A complete periodontal and medical examination was conducted on 31 patients scheduled for carotid endarterectomy. Subgingival samples and atheromatous plaques were microbiologically analyzed using nested polimerase chain reaction to improve the bacterial threshold detection level in atheroma. Histological analysis of atheromatous plaques was also performed.Results: All subgingival and atheroma samples were positive to at least one of the five target periodontopathogens. P.gingivalis, T.forsythia and F.nucleatum established a statistically significant relationship between the concomitant presence of bacteria in atheroma and periodontal pockets. A strong link was demonstrated between increased glucose serum levels and the presence of P.intermedia in atheroma. High lymphocytes serum levels were also strongly related to the detection of the five target periodotopathogens in atheroma. Conclusion: The concomitant presence of P.gingivalis, F.nucleatum, and T.forsythia in the subgingival plaque and atheroma samples suggests that these bacteria might play an important role in the development of atherosclerosis. Serum glucose levels could be responsible for the colonization of periodontopathogens in atheromatous plaques and the progression of cardiovascular disease. Atherosclerosis and periodontitis might be strongly linked by a direct and an indirect pathogenic pathway. / Antecedentes y Objetivos: Se ha descrito en la literatra una relación entre la periodontitis y algunas enfermedades sistémicas. Además, diversos estudios han demostrado una relación entre la aterosclerosis. Este estudio tuvo como objetivos (i) reforzar la relación entre ambas enfermedades evaluando la significancia estadística de la detección simultánea de cinco periodontopatógenos (A.actynomicetemcomitans, P.intermedia, T.forsythia, F.nucleatum and P.gingivalis) en bolsas periodontales y placas de ateroma de los mismos pacientes y (ii) analizar los factores de riesgo asociados a la aterosclerosis y/o periodontitis en la población de estudio. Materiales y Métodos: Se realizó un examen periodontal y médico completo en una población de 31 pacientes proramados para tromboendarterectomía carotídea. Las muestras de placa subgingival y de ateroma se analizaron microbiológicamente mediante reacción en cadena de la polimerasa (nested-PCR), para aumentar el umbral de detección bacteriana de las muestras de ateroma. Asimismos, se realizó un análisis histológico de las biopsias de placas de ateroma.Resultados: Todas las muestras subgingivales y de placas de ateroma fueron positivas para alguna de las cinco bacterias de estudio. P.gingivalis, T.forsythia y F.nucleatum demostraron una relación estadísticamente significativa entre la presencia simultánea en la bolsa periodontal y las placas de ateroma. Los niveles altos de glucosa en sangre y la presencia de P.intermedia en las placas de ateroma también demostraron una relación fuerte. Asimismo, niveles altos de linfocitos en sangre demostraron estar fuertemente relacionados con la detección de los cinco periodontopatógenos en las placas de ateroma.Conclusiones: la presencia concomitante de P.gingivalis, F.nucleatum y T.forsythia en las bolsas periodontales y las placas de ateroma de los mismos pacientes sugiere que estas bacterias juegan un papel importante en el desarrollo de la aterosclerosis. Los niveles de glucosa en suero y la carga bacteriana en las bolsas periodontales pueden ser responsables de la colonización de periodontopatógenos en las placas de ateroma y de la progresión de la enfermedad cardiovascular. Los resultados obtenidos sugieren que la periodontitis y la aterosclerosis pueden estar relacionadas tanto directamente como indirectamente.

Parodontit är en kronisk inflammatorisk sjukdom, som orsakas av patogena bakterier som fäster på tändernas ytor, där de bildar plack. Sjukdomen kan förebyggas genom god munhygien. Syftet med studien var att beskriva och jämföra parodontit relateradkunskap och dess relation till munhygiensvanor hos patienter före och 1-år efter icke kirurgisk parodontal behandling utförd av tandhygienist samt jämföra om det föreligger någon skillnad i kunskap efter behandling mellan två olika munhälsoundervisningsprogram. Ett ytterligare syfte var att beskriva om det föreligger någon skillnad i kunskap om parodontit med avseende på ålder, kön och utbildningsnivå. Studien var en beskrivande, jämförande studie med kvantitativ ansats och en del av en experimentell tvågruppsstudie.Urvalet bestod av 113 individer, 60 kvinnor och 53 män, i åldern 20-65 år som var remitteras till en specialistklinik i parodontologi. Av de 113 studiedeltagarna randomiserades 57 personer till ett individuell skräddarsydd munhälsoundervisningsprogram och 56 personer till ett standardiserat munhälsoundervisningsprogram. Ett frågeformulär med 11 påståenden gällande kunskap om parodontit och ett påstående om tandborstfrekvens samt ett påstående om approximalrengörning användes.Resultatet visade att patienterna hade mer kunskap efter icke kirurgisk parodontal behandling, men det fanns ingen skillnad mellan undervisningsprogrammen. Inget samband påvisades mellan kunskap om parodontit och utbildningsnivå, kön och ålder. Studien visar att både individuellt skräddarsydd munhälsoundervisning och standard munhälsoundervisning ledar till en ökad kunskap om parodontit mellan deltagarna.

In this dissertation I describe a model system to characterize the response of an oral bacterial pathogen, Aggregatibacter actinomycetemcomitans to the metabolic byproducts of a representative member of the oral flora, Streptococcus gordonii. A. actinomycetemcomitans is a causative agent of periodontal infections in humans. To cause infection, A. actinomycetemcomitans must overcome numerous challenges, including the host immune system and toxic metabolite production from other microbes. The most numerically dominant flora in the oral cavity are oral streptococci, which are well known for their ability to produce copious amounts of lactic acid and H₂O₂. By studying the response to H₂O₂ and lactic acid in pure and co-cultures, I have demonstrated that A. actinomycetemcomitans responds to these metabolites by several novel mechanisms that both enhance its survival in the presence of the host immune system and in the presence of the model oral streptococci S. gordonii. These studies have demonstrated that metabolites produced by normal flora can impact the survival of a single species in vivo as much as previously known virulence factors have done. In addition, I present a new method for measuring metabolite production in an attached cell population. This method is a novel application of scanning electrochemical microscopy (SECM) and I used this technique to study H₂O₂ production in the three dimensional space surrounding a multispecies biofilm in real time. In a related study I present the use of SECM to discover a novel redox chemistry phenomenon in the opportunistic pathogen Pseudomonas aeruginosa. / text

published_or_final_version / Dentistry / Master / Master of Dental Surgery

The human microbiome has important roles in maintaining health, but dysbiosis of the microbiota can lead to disease. Polymicrobial interactions can result in synergy, producing disease that is worse than the sum of the respective single species infections. Despite this significant impact, synergy is understudied due to the complexity of polymicrobial interactions. Periodontitis is a microbiome-associated disease, and is one of the most common infectious diseases worldwide. Therefore, we have used periodontal disease as a model to study polymicrobial synergy. I have used two complementary approaches to study polymicrobial infections. The opportunistic periodontal pathogen Aggregatibacter actinomycetemcomitans exhibits synergy with streptococci in model murine infections. Because polymicrobial interactions are dependent on organisms’ abilities to sense their environments, I have examined the genetic regulatory mechanisms used by A. actinomycetemcomitans to interact with its environment. Through Northern blot analyses and biochemical approaches, I show that A. actinomycetemcomitans uses non-coding RNAs to regulate amino acid transport. Taking a comparative genomics approach, I demonstrate that A. actinomycetemcomitans DNA uptake systems are evolutionarily linked to genome defense. To describe host-influenced changes in gene expression, I develop a new technique to transcriptionally profile A. actinomycetemcomitans in a murine abscess infection, thereby revealing the importance of specific fermentative and anaerobic respiratory genes for in vivo survival. The long-term goal is to use these studies as a basis to characterize genetic regulatory mechanisms mediating synergy in polymicrobial A. actinomycetemcomitans infections with streptococci and other oral microbes. As a second approach to study polymicrobial infections, I analyze gene expression of healthy and diseased human plaque communities from aggressive periodontitis patients. Profiling ribosome content of healthy and diseased communities, I show that disease communities adopt similar less diverse population structures distinct from healthy populations. In addition to changes in population composition, using community transcriptional profiling I show that a keystone species within diseased communities up-regulates expression of genes involved in making the oral inflammatory molecule butyrate. These studies demonstrate for the first time that microbiome based diseases are marked by gene expression changes in addition to compositional changes. / text

Diss. (sammanfattning) Stockholm : Karol inst., 2004. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 7 uppsatser.