Orientador: Juliane Maria Guerreiro Tanomaru / Resumo: Os cimentos reparadores endodônticos à base de silicato de cálcio apresentam biocompatibilidade e bioatividade. Porém, sua ação antimicrobiana é limitada. O acréscimo de óleos essencias pode favorecer as propriedades antimicrobianas de materiais. Os óleos essenciais são substâncias de origem vegetal com propriedades antimicrobiana, antiviral, antifúngica, antitoxigênica, antiparasitária e inseticida. Este estudo teve como objetivo avaliar a associação de diferentes óleos essenciais nas propriedades físico-químicas, citocompatibilida, potencial bioativo e atividade antibiofilme dos cimentos reparadores à base de silicato de cálcio, MTA Repair HP (MTA HP) e Biodentine (BIO). Publicação 1: avaliou a associação de 1,5% de Farnesol (FAR). Publicação 2: analisou o acréscimo de 1% de Thyme Essential Oil (TEO). Publicação 3: associou 1% de lemongrass oil (LEO). As propriedades físico-químicas de tempo de presa, solubilidade após 7 dias de imersão em água destilada e pH em 1, 3, 7, 14 e 21 dias foram avaliadas. A citocompatibilidade foi avaliada por meio dos testes de methyltetrazolium (MTT) e Vermelho Neutro (VN) após exposição das células Saos-2 às diferentes diluições dos eluídos dos materiais por 24h. A bioatividade foi avaliada pela atividade enzimática da fosfatase alcalina (ALP) nos períodos de 1, 3 e 7 dias. Nódulos de mineralização foram também quantificados após 21 dias pela coloração com vermelho de Alizarina (ARS). A capacidade de inibição de Metaloproteinase de Matriz (MM... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

Indiana University-Purdue University Indianapolis (IUPUI) / Introduction: Nonsurgical root canal therapy procedures aim to reduce the total microbial load within an infected root canal system through chemomechanical debridement of the root canal system via instrumentation in conjunction with an antibacterial irrigating solution. The most commonly used irrigant is sodium hypochlorite, often at concentrations toxic to human cells. Electromagnetic wave irradiation is a novel method of disinfection that has been shown to be bactericidal against planktonic microorganisms in solution, but its efficacy against an established biofilm is unknown. Pilot studies have demonstrated a synergistic killing effect with sodium hypochlorite through a process termed electromagnetic stimulation (EMS). If confirmed, lower concentrations of the current gold standard of 6.0-percent sodium hypochlorite could be used to irrigate infected root canals during endodontic treatment, resulting in less toxicity to human cells. There are also regenerative implications as EMS could be used to disinfect the root canals of immature teeth using 1.5-percent sodium hypochlorite, as recommended by the American Association of Endodontists. Objectives: The purpose of this in-vitro study was to evaluate the anti-biofilm effect of EMS against an established biofilm of Enterococcus faecalis. Materials and Methods: Single rooted teeth were cut to a standardized length (12 mm) and instrumented with a 45.05 Wave One Gold reciprocating file. Specimens were sterilized and inoculated with E. faecalis, which grew for two weeks to form an established biofilm. There were five treatment groups: 1) 6.0-percent sodium hypochlorite; 2) 1.5-percent sodium hypochlorite; 3) 1.5-percent sodium hypochlorite with EMS; 4) 0.9-percent saline with EMS and 5) 0.9-percent saline. Samples were collected, plated, and incubated for two days. The number of CFUs/mL was determined and converted to log10. The effect of treatment group on bacterial counts was made using Wilcoxon Rank Sums Test. One sample per group was scored and split for confocal imaging. Null Hypothesis: Teeth treated with EMS in combination with 1.5-percent sodium hypochlorite or 0.9-percent saline will not demonstrate a significant anti-biofilm effect in comparison to those treated with 6.0-percent sodium hypochlorite alone. Results: 0.9-percent saline and 0.9-percent saline with EMS were significantly higher than 6.0-percent NaOCl, 1.5-percent NaOCl, and 1.5-percent NaOCl with EMS. 0.9-percent saline was significantly higher than 0.9-percent saline with EMS. The three groups that included treatment with NaOCl were not significantly different from each other. Confocal imaging confirmed the CFU findings. Conclusion: Because there was no growth in any of the NaOCl groups, the null hypothesis cannot be rejected. However, there was an antibiofilm effect when comparing the two saline groups, demonstrating that EMS has an antibiofilm effect. Future studies should focus on determining what concentration of NaOCl is most effective in combination with EMS.

Indiana University-Purdue University Indianapolis (IUPUI) / Introduction: One of the main objectives of endodontic therapy is to reduce microbes and remove inflamed pulpal tissue within the root canal system (RCS). This is accomplished through chemomechanical debridement of the RCS using hand and rotary instrumentation along with an antimicrobial irrigant. Today, the most commonly used irrigant is sodium hypochlorite (NaOCl), often at concentrations toxic to human cells. The use of ozone as an endodontic irrigant is a novel technique that has been proven to be antimicrobial against several microorganisms. However, independent research is lacking on ozone’s efficacy against an established endodontic biofilm. If ozone’s efficacy against biofilms is confirmed, the use of toxic and potentially dangerous sodium hypochlorite could be replaced in some clinical situations (i.e., regeneration, immature teeth, resorption) with a safer and effective alternative. Objective: The aim of the current study was to evaluate the anti-biofilm activity of different concentrations of ozonated water compared to various concentrations of NaOCl against an established endodontic biofilm of Enterococcus faecalis in root canal treated teeth in vitro. Materials and Methods: The crowns of similarly sized, maxillary anterior teeth were removed, and the roots cut to a standard length (12 mm). All root canals were instrumented to a standard size. Specimens were sterilized and then inoculated with E. faecalis, which were allowed to grow for two weeks to form an established biofilm. There were six treatment groups: 1) 6% NaOCl; 2) 1.5% NaOCl; 3) 16µg/mL ozonated water; 4) 25µg/mL ozonated water; 5) 50µg/mL ozonated water, and 6) saline. Following treatment, samples were collected, plated, and incubated for two days. The number of CFU/mL were determined, and samples visualized using confocal imaging. The effect of treatment group on bacterial counts was made using one-way ANOVA followed by pair-wise comparisons. Null Hypothesis: Endodontically treated teeth irrigated with ozonated water will not demonstrate a statistically significant decrease in the E. faecalis biofilm compared to those treated with sodium hypochlorite Results: CFUs were converted to log10 and compared using Fisher’s Exact tests or one-way ANOVA followed by pair-wise tests. In all observations utilizing NaOCl irrigation, no colonies formed following treatment. The two NaOCl groups, with 0 CFU/mL, were significantly different than the other four groups (p=0.009). Saline showed a trend towards higher CFU/mL than 50 µg/ml O3 (p=0.068). None of the other comparisons approached statistical significance (p=0.453 25 µg/ml O3, p=0.606 16 µg/ml O3, p=0.999 25 µg/ml O3 vs 50 µg/ml O3, p=0.990 16 µg/ml O3 vs 50 µg/ml O3, p=1.000 16 µg/ml O3 vs 25 µg/ml O3). Confocal imaging helped illustrate effects of irrigation and confirm CFU findings. Conclusion: The results of this study failed to reject the null hypothesis. There was a statistically significant difference in the E. faecalis biofilm remaining in the groups treated with ozonated water compared to those treated with NaOCl. However, there was a trend towards higher CFU/mL in the saline group compared to the 50µg/mL ozonated water group. According to this finding, future studies should evaluate the effects of higher concentrations of ozonated water against an established E. faecalis biofilm. In addition, other follow-up studies might include ozonated water’s effect on human cells, such as the stem cells of the apical papilla that are so critical to the success of regenerative endodontic procedures. Due to university and laboratory closures caused by the COVID-19 pandemic, this project was stopped short and an insufficient sample size did not allow for proper statistical power. Additional occasions should be run upon the university’s re-opening to allow for proper statistical power.

Doctor of Philosophy / Department of Biology / Lynn E. Hancock / The enterococci are gaining much notoriety as common nosocomial pathogens. One aspect of their pathogenesis, especially characteristic to infectious endocarditis and urinary tract infections, involves their ability to transition from the sessile state of existence to surface adherent structured communities called biofilms. Existence as biofilms, affords enterococci protection against a number of growth limiting challenges including antibiotic therapy and host immunity. In the current study a mechanistic role for two Fsr quorum-regulated extracellular proteases- gelatinase (GelE) and its cotranscribed serine protease (SprE), were explored in biofilm development of E. faecalis V583. Confocal imaging of biofilms suggested that GelE[superscript]– mutants were significantly reduced in biofilm biomass compared to V583, whereas the absence of SprE appeared to accelerate the progression of biofilm development. Culture supernatant and biofilm analysis confirmed that decreased biofilms observed in GelE[superscript]– mutants resulted from their inability to undergo autolysis and release extracellular DNA (eDNA) in planktonic and biofilm cultures, whereas SprE[superscript]– mutants produced significantly more eDNA as components of the biofilm matrix. The governing principle behind GelE mediated autolysis and eDNA release in E. faecalis V583 was demonstrated to be fratricide. GFP reporter assays of V583 populations confirmed that GBAP (gelatinase biosynthesis-activating pheromone encoded by fsrD) quorum non-responders (GelE[superscript]–SprE[superscript]–) were a minority subpopulation of prey cells susceptible to the targeted fratricidal action of the quorum responsive predatorial majority (GelE[superscript]+SprE[superscript]+). The killing action is dependent on GelE, and the GelE producer population is protected from self-destruction by the co-production of SprE as an immunity protein. Targeted gene inactivation and protein interaction studies demonstrate that extracellular proteases execute their characteristic effects following downstream interactions with the primary autolysin, AtlA. Finally, comparison of virulence effects of isogenic extracellular protease mutants (∆gelE, ∆sprE and ∆gelEsprE) relative to parental strain (V583) in a rabbit model of enterococcal endocarditis confirmed a critical role for GelE in the infection process. In conclusion, the data presented in this thesis are consistent with significant roles for GelE and SprE in biofilm mediated pathogenesis of enterococcal infections.

The study objective was to compare the antimicrobial activity of STERIPLEX™ HC with 5.25% sodium hypochlorite (NaOCl) at different dilutions (50%, 25%, 10%, 1%, 0.1%) and different time intervals (1, 3, 5 minutes) on Enterococcus faecalis. All data was analyzed using an ANOVA. The 50%, 25%, and 10% dilutions of both disinfectants reduced the colony forming unit (CFU) count to below the limit of detection (50 CFU/ml) after one minute. The 1% dilutions at each of the time intervals show NaOCl was significantly more effective than STERIPLEX™ HC (all Ps < .0001) in reducing the CFU/ml count. The 0.1% dilutions of NaOCl and STERIPLEX™ HC at 1 minute, were not different (P = 0.7808), while at 3 minutes and 5 minutes NaOCl was significantly more effective (P = 0.0098 and P < .0001, respectively).

El objetivo del presente estudio fue determinar el efecto antibacteriano de la combinación de droga 3Mix y MP y de sus combinaciones alternativas contra Enterococcus faecalis y Fusobacterium nucleatum. Se empleó el método de dilución en caldo para determinar la concentración inhibitoria mínima (CIM) y la concentración bactericida mínima (CBM) y método de difusión en agar modificado para determinar el efecto antibacteriano de los vehículos. Se emplearon dos cepas ATCC Enterococcus faecalis y Fusobacterium nucleatum, con la combinación de componentes de la droga 3Mix, 3Mix-Cefaclor(reemplazo de minociclina por cefaclor) y 3Mix-Amoxicilina(reemplazo de minociclina por cefaclor) en las siguientes concentraciones: 25µg/ml; 6,25µg/ml; 1,56µg/ml; 0,39µg/ml; 0,195µg/ml; 0,097µg/ml y macrogol(M), propilenglicol(P) y su asociación. La CIM para 3Mix, 3Mix-cefaclor fue 0,39µg/ml y 0,195µg/ml para 3Mix-Amoxicilina mientras que CBM fue >25µg/ml; 25µg/ml; 6,25µg/ml respectivamente sobre Enterococcus faecalis, para Fusobacterium nucleatum la CIM de 3Mix, 3Mix-Cefaclor fue 0,195µg/ml y ≤0,097µg/ml para 3Mix-Amoxicilina, los cuales coincidieron con CBM. Se obtuvo inhibición de crecimiento bacteriano por parte macrogol y propilenglicol+macrogol, sin embargo propilenglicol no formó halo de inhibición sobre Enterococcus faecalis ni Fusobacterium nucleatum. La Combinación de droga 3Mix, 3Mix-Cefaclor y 3Mix-Amoxicilina presentaron efectos antibacterianos contra Enterococcus faecalis y Fusobacterium nucleatum.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Enterococcus faecalis (E. faecalis), conhecidamente patógeno oportunista, tem sido frequentemente associado a infecções sistêmicas graves. É também encontrado na cavidade oral, com destaque em infecção endodôntica refratária. O objetivo deste estudo foi avaliar características moleculares de E. faecalis isolados de infecção endodôntica primária no Brasil e comparar com isolados orais e não orais de pacientes do Reino Unido e do Japão, assim como E. faecalis resistentes à vancomicina. O presente estudo também investigou o relacionamento entre E. faecalis de diferentes origens (oral e não oral) e de diferentes áreas geográficas para obter uma melhor compreensão do envolvimento dos diferentes reservatórios no surgimento e propagação de clones virulentos, aqueles que possuem genes que conferem infectividade e virulência, assim como resistência aos antibióticos. Para tal, foram estudados E. faecalis isolados em infecções endodônticas no Brasil (n = 20) e orais no Reino Unido (n = 10), e em infecções não orais no Japão (n = 9). Além disso, 20 E. faecalis isolados ambientais do Hospital Universitário de Gales (Cardiff, Reino Unido), classificados como Enterococcus resistentes à vancomicina (VRE) também foram examinados. A Concentração Inibitória Mínima (CIM) dos isolados do Brasil foi obtida pelo método de diluição em agar de acordo com as recomendações do Clinical and Laboratory Standards Institute (CLSI). Reação em cadeia da polimerase (inglês - PCR) foi a técnica empregada para detectar os genes de virulência e aqueles associados à resistência aos antibióticos, enquanto Reação de Amplificação Aleatória de DNA Polimórfico (inglês - RAPD-PCR) foi escolhida para a tipagem molecular. Dentre os genes de virulência examinados, o gene que codifica a gelatinase gelE foi o mais prevalente entre os isolados (77-100%). Entre isolados orais, foram detectados os genes agg de substâncias de agregação, esp de proteína de evasão imune, cylB de citolisina, genes de resistência à tetraciclina tetM e tetL e à eritromicina ermB com diferentes prevalências. Os isolados clínicos hospitalares do Japão apresentaram perfil genético similar aos isolados orais, mas com maior prevalência de ermB e cylB. Todas as amostras de VRE foram positivas para os genes gelE, esp, agg, vanA, ermB e tetM, 95% foram positivos para cylB e 17% positivo para tetL. Todas as amostras foram negativas para ermA, asa373, vanB, vanC1 e vanC2/3. RAPD-PCR revelou agrupamento de VRE em comparação com outros isolados. Neste estudo, os isolados de E. faecalis de infecções orais apresentaram genes de resistência à tetraciclina, um antimicrobiano frequentemente usado no tratamento local de infecções dentárias, abrindo um debate muito importante sobre o papel e a eficácia desta droga para infecções orais. Claramente, são necessários mais estudos nesta área principalmente em relação à expressão de fatores de virulência entre isolados endodônticos para melhor nortear as estratégias de tratamento. As pressões externas no microambiente dos canais radiculares podem ser responsáveis pela seleção de espécies mais resistentes e virulentas. Por fim, embora isolados orais apresentem genes de virulência fundamentais para a patogenicidade, estes foram detectados em menor incidência em comparação com os isolados não-orais e VRE. / Enterococcus faecalis is an opportunistic pathogen known to cause serious systemic infection. It is also encountered in the oral cavity and has been implicated in persistent root canal infection. The aim of this study was to evaluate a range of molecular characteristics of E. faecalis isolated from primary endondontic infections in Brazil and compare to isolates from oral and non-oral infections in patients from UK and Japan, as well as isolates of vancomycin resistant E. faecalis, VRE, from a hospital environment. The present study was undertaken to explore the relatedness of E. faecalis from different origins, oral and non oral, and from different geographic areas to gain a better understanding of the involvement of the different reservoirs in the emergence and spread of virulent clones, those that acquired a number of genes conferring infectivity and virulence and in addition antibiotic resistance. To do this, E. faecalis from oral infections in Brazilian (n=20) and UK patients (n=10), and non-oral infection in japanese patients (n=9) were studied. In addition, 20 environmental VRE isolates from the University Hospital of Wales (Cardiff, UK) were also examined. For braziliam isolates, antimicrobial susceptibility was ascertained by agar dilution, using the recommendations of the Clinical and Laboratory Standards Institute (CLSI). For all isolates, PCR with validated primers was used to detect genes associated with antibiotic resistance and virulence, whilst RAPD-PCR was used to fingerprint isolates. Of the virulence genes examined, gelatinase gene gelE was most prevalent amongst isolates (77-100%). In the case of oral isolates, the genes of aggregation substances agg, immune evasion protein esp, cytolysin cylB, tetracycline resistance tetM and tetL and erythromycin resistance ermB were detected with varying prevalence. Japanese hospital isolates had a similar genetic profile to oral isolates but with higher prevalence of ermB and cylB. All VRE strains were positive for gelE, esp, agg, vanA, ermB and tetM, 95% were positive for cylB and 17% positive for tetL. All isolates were negative for ermA, asa373 vanB, vanC1 and vanC2/3. RAPD-PCR revealed clustering of VRE compared with other isolates. In this study, isolates of E. faecalis from oral infections showed antibiotic resistance genes for tetracycline, an agent used in the local treatment of dental infection. This opens up a much-needed debate on the role and efficacy of this antibiotic for oral infections. Clearly, more research in this area is required particularly in relation to the possession and expression of virulence factors in the root canal environment, to better inform our management strategies. Environmental pressures in root canals may be responsible for the selection of more resistant species and the possession of virulence determinants. This knowledge is important in guiding procedures for controlling the increasing problem of antibiotic resistance amongst clinically relevant bacteria. Furthermore, whilst oral isolates had genes that could contribute to pathogenicity, these were detected at lower incidence compared with non-oral and VRE isolates.

Orientador: Rogério de Castilho Jacinto / Coorientadora: Carolina Simonetti Lodi / Banca: Luciano Tavares Angelo Cintra / Banca: João Eduardo Gomes Filho / Banca: Francisco Montagner / Resumo: O presente estudo teve como objetivo avaliar a atividade antimicrobiana dos cimentos endodônticos, com ou sem associação do uso prévio de hidróxido de cálcio em um modelo "in vitro" de biofilme. Espécimes de dentina bovina (240) foram colocadas e deixas em contato direto com inoculo de E. faecalis (ATCC 51299) por 14 dias, para induzir a formação do biofilme. Em seguida, metade das espécimes foram incubadas (37⁰C e 5% CO2) em contato com um dos seguintes cimentos: AH Plus, Acroseal e Sealapex por 2, 7 e 14 dias, e a outra metade foi tratada com solução de hidróxido de cálcio por 14 dias e incubada em contato com os cimentos AH Plus, Acroseal e Sealapex por 2, 7 e 14 dias. Cada grupo continha um n = 8. Após cada período experimental, as amostras foram agitadas e as suspensões formadas foram diluídas em série e triplamente plaqueadas em ágar m-Enterococcus. As unidades formadoras de colônias foram contadas, e os dados foram analisados estatisticamente usando os testes one-way ANOVA, Shapiro-Wilk e Kruskal-Wallis (p <0,05) para determinar o potencial antimicrobiano. Foi observada diferença estatisticamente significante entre os grupos com e sem o tratamento com Hidróxido de Cálcio, para todos os cimentos avaliados. Entretanto, nenhum dos cimentos testados foi capaz de eliminar completamente o biofilme. Ao comparar os cimentos, Sealapex reduziu E. faecalis após 7 dias, enquanto AH Plus e Acroseal mostraram atividade antimicrobiana apenas no 14º dia experimental. Em conclusão, o u... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present study aimed at evaluating the antimicrobial activity of endodontic sealers, with or without prior use associationof calcium hydroxide in an in vitro biofilm model. Bovine dentin specimens (240) were placed and left in contact with inoculum of E. faecalis(ATCC 51299) for 14 days, to induce biofilm formation. Then, half of the specimens were incubated (37⁰C and 5% CO2) in contact with one of the following sealers AH Plus, Acroseal and Sealapex for 2, 7 and 14 days, and the other half were treated with calcium hydroxide solution for 14 days, and then incubated in contact with the sealers AH Plus, Acroseal and Sealapex for 2, 7 and 14 days. Each group comprised a n=8. After each experimental time the samples were agitated, and the suspensions formed were serially diluted, and triple plated onto m-Enterococcus agar. Colony forming units were counted, and the data were statistically analyzed using ANOVA, Shapiro-Wilk and Kruskal-Wallis one-way tests (p<0.05) to determine antimicrobial potential. A statistically significant difference was observed between the groups with and without the treatment with Calcium Hydroxide, for all sealers evaluated. However, neither of the sealers tested were able to completely eliminate the biofilm.When comparing the sealers, Sealapex reduced E. faecalisafter 7 days, while AH Plus and Acroseal showed antimicrobial activity only on the 14th experimental day. In conclusion, previous use of calcium hydroxide helped to decrease Enterococcus faecalisbiofilm of the sealers studied in all experimental times. (Complete abstract electronic access below) / Doutor

Three Streptococcal strains: S. milleri P213, S. milleri P35 and S. milleri B200 and three enterococcal strains: E. faecalis 123, E. faecalis 126 and E. faecium were used to test for vancomycin resistance. Two strains were used as reference strains that were already characterized as vancomycin resistant. E. faecium BM4147 was used as a VanA control and E. faecalis ATCC was used as a VanB control. Susceptibility of each strain to this antibiotic was tested by disk-diffusion assay and the MIC values for the strains were found to be between 5 - 10 ug/ml and for the VanA control, the MIC was > 64 ug/ml and for the VanB control was 32 ug/ml. These MIC values indicate that S. milleri P213, S. milleri P35, S. milleri B200, E. faecalis 123, E. faecalis 126, and E. faecium are all of the VanC phenotype. All strains were tested for lysis by means of addition of vancomycin (10 ug/ml) to the bacterial cultures. Lytic curves were constructed and the VanB control was found to be most autolytic upon addition of vancomycin and E. faecalis 123 was the least autolytic. However, under normal conditions in phosphate buffer, lytic curves showed that S. milleri P213 was the most autolytic and the VanA control, the least autolytic. PCR assays were performed to detect specific antibiotic resistant genes. Primers were selected from Dukta-Malen et al., 1995. The VanA primer yielded amplification of 732 bp for only the VanA control DNA and the VanB primer set yielded products for the VanB control DNA. S. milleri P213, P35, B200 and E. faecalis 123 and 126, and E. faecium DNA were amplified with the VanC primers. This supports the results obtained in MIC that these strains are possibly VanC resistant strains. Amplified VanA control and that of E. faecalis 126 were thereafter sequenced. VanA control amplicon was correctly amplified since it showed homology to E. faecium BM4147 as well as the VanB amplicons which was found to be homologous to the transposon Tn1549 found on the well-characterized E. faecalis strain which is known to harbour the VanB vancomycin-resistant genes. Whilst E. faecalis 126 which represented the VanC phenotype showed 96% homology to E. gallinarum BM4147 which is a well-characterized glycopeptide-resistant enterococci belonging to the VanC phenotype. Southern blots were performed using specific primers as a probe to verify whether the gene sequences for the specific genotype were present in these strains and results confirmed those found in the PCR assays and in DNA sequencing. The peptidoglycan precursors of each strain were arrested in vancomycin (20 ug/ml) to block transpeptidation and transglycosylation steps of peptidoglycan synthesis and bacitracin (100 ug/ml) was used to amplify precursors at the transglycosylation step. Precursors were extracted and analysed by reverse-phase HPLC. UDP-MurNAc-tetrapeptides cell wall precursors, which are found abundantly in vancomycin-resistant strains, were found in large proportions in all strains, except in E. faecalis 123 when arrested with vancomycin. This precursor has a noticeably decreased affinity for vancomycin, hence contributing to its resistance. The precursor accumulated when arrested with bacitracin, was, UDPMurNAc-tetrapeptide in all strains except in E. faecalis 126. UDP-MurNAc-pentapeptides were also found in moderate amounts in most strains. The molecular masses of the peptidoglycan precursors obtained from mass spectrometry correctly identified them. This confirmed that the bacterial strains investigated were in fact resistant to the antibiotic vancomycin and this study shows that results obtained from conventional phenotypical screening methods reliably correlated with the genotypes classified using more advanced techniques such as PCR, southern blot/hybridisation and DNA sequencing. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Thesis (M.S.D.)--Indiana University School of Dentistry, 2010. / Title from PDF t. p. (viewed July 28, 2010) Advisor(s): Mychel Vail, Chair of the Research Committee, Richard Gregory, Joseph Legan, Kenneth Spolnik, Susan Zunt. Curriculum vitae. Includes abstract. Includes bibliographical references (leaves 108-120).