No description available.

Methicillin-resistant Staphylococcus aureus (MRSA) is a successful pathogen which was historically found in hospital settings but now is a common cause of infection in communities. The rapid emergence of community-acquired MRSA (CA-MRSA) at the turn of the 21st century has established this bacterium’s presence throughout the globe and MRSA continues to be endemic in certain countries. Asia is the most populous continent in the world and also holds a high burden of MRSA infection. This presents a concern for both public health and the acquisition of antibiotic resistance in this region. This literature review describes how MRSA became a successful pathogen. It provides a systematic review of the recent literature on MRSA in East Asia to identify major MRSA clones by country as determined by their molecular characteristics. Also to identify notable genetic and epidemiological factors associated with these MRSA clones. The results of this survey provided evidence of the importance of using molecular categorization techniques to accurately distinguish MRSA strains that require specific antibiotic treatment methods. It also provided evidence of CA-MRSA clones invading hospital settings and traditional hospital-acquired MRSA (HA-MRSA) clones continuing to develop multi-drug resistance throughout East Asian countries. The results also detected novel MRSA strains across hospitals and reported the spread of major MRSA clones within and between countries. Strengthening existing surveillance systems and collaborative efforts between countries within Asia should be a priority to monitor the evolution and movement MRSA especially in the age of globalization and accessible travel.

Erythromycin is a macrolide antibiotic that inhibits not only mRNA translation but also 50S ribosomal subunit assembly in bacterial cells. An important mechanism of erythromycin resistance is the methylation of 23S rRNA by erm methyl transferase enzymes. A model for 50S ribosomal subunit formation suggests that the precursor particle which accumulates in erythromycin treated cells is the target for methyl transferase activity. Hybridization experiments identified the presence of 23S rRNA in the 50S precursor particle. The protein content of the 50S precursor particle was analyzed by MALDI-TOF mass spectrophotometry. These studies have identified 23 of 36 50S ribosomal proteins in the precursor. Methyltransferase assays demonstrated that the 50S precursor particle was a substrate for ermE methyltransferase. Competition experiments indicated that the enzyme could displace erythromycin from the 50S precursor particle and that the methyltransferase had a higher association constant for the precursor particle compared to that of erythromycin. Inhibition experiments showed that macrolide, lincosamide and streptogramin B compounds bound to the precursor particle with similar affinity and inhibited the ermE methyltransferase activity. These studies shed light on the interaction of ermE methyltransferase and erythromycin in this clinically important pathogen.

No description available.

No description available.

Syftet med denna studie var att undersöka den antibakteriella effekten hos ett polyestertyg med tunna invävda koppartrådar. Frågeställningen som skulle besvaras var ifall koppartyget hade en baktericid eller bakteristatisk effekt. Koppartyget är ännu i prototypstadie och om det visar sig ha antibakteriella egenskaper är det tänkt att användas inom klinisk verksamhet för att förhindra bakterietillväxt i sår och andra känsliga lokaler. Koppar är ett essentiellt spårämne, men har också antimikrobiella egenskaper som utövas genom ett brett spektra av mekanismer där skador på cellmembranet är en av de viktigare. Metoderna som användes för att inokulera bakterier på tyget var absorptionsmetoden, där en näringsbuljong innehållande Staphylococcus aureus ATCC 6538 pipetterades på tygproverna, och transfermetoden där tygproverna trycktes mot en agar som racklats med peptonsaltlösning innehållande S. aureus. Totalantalet viabla bakterier per tygprov beräknades efter kort kontakt (<1min) och inkubering (18-24 h vid 37±2°C) genom att räkna viable count. Resultaten efter inkubering visade signifikant skillnad i totalantal bakterier mellan koppartyget och negativ kontroll i tre av fyra försök. Kort kontakt visade tendens till viss antibakteriell effekt. Slutsatsen är att koppartyget skadade och dödade bakterier då de fick inkubera på tyget, medan fler försök behövs för att säkerställa effekten av kort kontakt med koppartyget. / The purpose of this study was to test the antibacterial effect of thin copper treads woven into a polyester fabric. The investigation was done by inoculation of Staphylococcus aureus strain ATCC 6538 to the fabric and evaluation of the number of viable cells post exposure by viable count. The issue to be answered was whether the copper fabric had a bactericide or bacteriostatic effect? The fabric is still in prototype stage, and if proven to have antibacterial properties the aim is to use it to prevent bacterial growth in wounds and other vulnerable locations in clinical care. Copper is an essential trace element, but also has antimicrobial properties through a wide range of mechanisms where cell membrane damage is one of the more important. Methods used for inoculation was the absorption method, where a nutrient broth containing S. aureus was pipetted on to the fabric specimens, and the transfer method where the fabric specimens were pressed onto an agar plate that had previously been spread with peptone salt solution containing S. aureus. Total number of bacteria per fabric specimen after short contact (<1 min) and incubation (18-24 h at 37±2°C) was calculated. Incubation showed significant difference in total number of bacteria between the copper fabric and negative control in three of four tests. Short contact showed a tendency of antibacterial effect. The conclusion was that the copper fabric harmed and killed bacteria during incubation but that more records would be needed to be sure about the effects of short contact on bacteria.

Staphylococcus aureus est une bactérie pathogène portée par 30% de la population humaine. Cette bactérie agressive est responsable d'1/5ème des maladies acquises à l’hôpital (infections nosocomiales). Le passage d’un état commensal (portage) à un état infectieux implique le contrôle de l’expression de facteurs de virulence (toxines, adhésines…) ; ce qui nécessite un large arsenal de régulateurs bactériens comprenant des protéines (facteurs de transcription) et des ARN régulateurs (ARNrég). Parmi ces derniers, l’ARN Srn_3610_SprC est impliqué, entre autres, dans la prévention de la phagocytose et dans l’atténuation de la virulence de la bactérie. Or, cet ARN, dont l’expression est habituellement faible, se retrouve fortement exprimé durant les premières minutes de la phagocytose. Le but de cette thèse a été d’identifier les régulateurs transcriptionnels de srn_3610_sprC. SarA, un des facteurs de transcription majeur de S. aureus impliqué dans de nombreuses étapes clé de la virulence (antibiorésistance, formation de biofilm…), a été caractérisé comme le répresseur fort de l’expression de srn_3610_sprC. L’identification du site de fixation de SarA sur le promoteur de ce gène a permis de révéler un second ARNrég, Srn_9340, dont l’expression est également réprimée par SarA. Dans les 2 cas, SarA empêche la fixation de l’ARN polymérase sur leur promoteur, entrainant un faible niveau de transcription. La recherche du signal permettant l’induction de la transcription de ces gènes via le décrochage de SarA est en cours. En parallèle, les données de fixation de SarA sur ces 2 promoteurs ont permis d’identifier de nouvelles cibles de SarA. Nous poursuivrons cette recherche de cibles via une analyse à haut débit par RNASeq. / Staphylococcus aureus is a bacterial pathogen responsible for about 1/5 of health-care associated infections. Nevertheless, 30% of humans are healthy carriers of this bacterium. Switch from commensal to infectious mode requires that virulence factors (toxins, adhesins), involved in S. aureus pathogenicity, are regulated by transcription factors (TF) and small non-coding RNA (sRNA). One of these sRNA, Srn_3610_SprC, has a key-role in prevention of phagocytosis and in attenuation of S. aureus virulence. Whereas srn_3610_sprC is usually poorly expressed, its expression is up-regulated during the first minutes of phagocytosis process. The aim of this thesis was to identify TF regulating srn_3610_sprC expression. We characterized SarA, the main TF of S. aureus, as a repressor of srn_3610_sprC transcription. Following SarA binding site determination, we highlighted a second sRNA (Srn_9340) also transcriptionally repressed by SarA. For both sRNA, SarA prevents RNA polymerase binding on their promoters. The next challenge will be to determine SarA derepression signal allowing high level of sRNAs transcription. Meanwhile, researches on SarA binding sequences allowed us to identify new SarA targets. To better understand SarA functions in S. aureus (antibiotic resistance, biofilm formation), we are now initiating a global study for the determination of SarA targets.

La pyocyanine (PYO) est une phénazine de couleur bleu-vert, produite spécifiquement par la bactérie pathogène opportuniste Pseudomonas aeruginosa (Pa). La toxicité aérobie de la PYO envers les cellules de mammifères, les levures et les bactéries a été décrite de longue date, mais la compréhension des mécanismes d’action est encore lacunaire, en particulier en conditions de limitation en O2 (conditions rencontrées dans le contexte infectieux). De plus, il a récemment été montré que la PYO peut apporter des effets bénéfiques pour la souche productrice en hypoxie. Au cours de ce travail, nous avons réexaminé les effets de la PYO sur un large panel de bactéries dont son propre producteur (Pa) ainsi que sur un modèle cellulaire eucaryote Saccharomyces cerevisiae exposées à différentes tensions en O2. Nos données suggèrent que la toxicité aérobie de la PYO envers S. cerevisiae est multifactorielle, impliquant à la fois une interaction avec le complexe III de la chaîne respiratoire et l’induction d’un stress oxydatif. Pour la première fois, nous avons mis en évidence une toxicité de la PYO exacerbée en anaérobiose chez un eucaryote (S. cerevisiae). Le mécanisme d’action impliquerait le PYO radical. Nous avons également montré que la PYO peut inhiber la croissance aérobie et anaérobie des microorganismes concurrents, plus particulièrement S. aureus en bloquant le complexe III de la chaîne respiratoire. A l’inverse, la PYO peut stimuler la respiration de Pa surtout dans les conditions mimant le contexte infectieux (hypoxie, vie ralentie). Le complexe III et/ou les oxydases terminales cbb3 serait impliqué favorablement. En conclusion, la PYO jouerait à la fois un rôle de poison hypoxique mais aussi un rôle de navette redox bénéfique pour la survie et la virulence de Pa en hypoxie. / Pyocyanin (PYO) is a blue-green phenazin, specifically produced by the opportunistic bacterium Pseudomonas aeruginosa (Pa). Aerobic toxicity of PYO toward mammalian cells, yeast and bacteria has been known for a long time, but the understanding of its mechanisms of action remains unclear, especially in conditions of limited O2 (conditions encountered during infection). In addition, it has recently been shown that PYO can bring benefits to the producer strain under hypoxia. In this study, we reexamined the effects of PYO toward a large panel of bacteria including its own producer Pa as well as a model of eukaryotic cells Saccharomyces cerevisiae exposed to different oxygen tensions. Our results suggest that the aerobic toxicity of PYO toward S. cerevisiae is multifactorial: involving both interaction with the respiratory chain at the level of complex III and induction of oxidative stress. For the first time, we have shown that PYO exerts an increased toxicity toward the eukaryotic cell, S. cerevisiae under anaerobiosis. The mechanism could involve the production of PYO radical. We have also shown that PYO can inhibit the aerobic and anaerobic growth of competing microorganisms, especially S. aureus by blocking the complex III of the respiratory chain. Conversely, PYO can stimulate the respiration of Pa, in mainly in conditions similar to those encountered during infection (hypoxia, slowed growth). The complex III and/or the cbb3 oxidases could be favorably involved. To conclude, PYO could act as a hypoxic poison as well as a redox shuttle beneficial for the survival and the virulence of Pa under hypoxia.

As condições de produção de queijos frescos são favoráveis à ocorrência e à produção de enterotoxinas produzidas por estafilococos, sendo estes os principais micro-organismos relacionados aos casos de intoxicação alimentar no mundo, tornando-se necessários estudos sobre a rastreabilidade das fontes de contaminação durante a fabricação, identificação genotípica e habilidade de cepas em produzir enterotoxinas. Este trabalho teve como objetivo isolar e identificar estafilococos positivos para o teste de coagulase, potencialmente produtores de enterotoxinas em laticínios do estado de São Paulo, desde o leite recebido até o produto final. A técnica da mPCR foi utilizada para identificar três espécies de Staphylococcus coagulase-positiva (S. aureus, S. hyicus e S. intermedius) entre os isolados obtidos de diferentes pontos de processamento em laticínios do Estado de São Paulo. O perfil genético das cepas foi avaliado através da comparação de bandas pela técnica Enterobacteria Repetitive Intergenic Consensus (ERIC-PCR) e graficamente demonstrados por um dendrograma. O DNA de 102 cepas isoladas, de amostras de leite cru, leite pasteurizado, coágulo, manipulador, superfícies de equipamentos de laticínios do Estado de São Paulo e queijos foi extraído e submetido à reação em cadeia da polimerase (PCR), utilizando-se primers específicos para a detecção de fragmentos dos genes envolvidos na síntese das toxinas (SE) do tipo A, B, C, D, E, G, H, I e J. Das 102 cepas avaliadas, 5 apresentaram amplificação do fragmento do gene responsável pela codificação da toxina A, 3 para toxina C, 56 para toxina G, 59 para toxina H, 9 para toxina I, e nenhuma para toxinas B, D, E e J. Amostras de leite cru, leite pasteurizado e queijos produzidos nos laticínios e dos isolados de Staphylococcus spp. coagulase positiva que apresentaram ao menos algum dos genes relacionados à produção de toxinas clássicas (A, B, C, D e E) foram submetidos a um teste de detecção de enterotoxinas pelo sistema VIDAS® Staph Enterotoxin (SET2). Os dados obtidos para a identificação molecular das cepas, da ocorrência de cepas portadoras dos genes relacionados à produção de enterotoxinas e da produção fenotípica das enterotoxinas foram submetidos ao teste qui-quadrado. O presente trabalhou confirmou que o risco de intoxicação estafilocócica é real, pois foi encontrada enterotoxina em amostras de leite pasteurizado e queijos. / The production conditions of fresh cheese are favorable to the occurrence and production of enterotoxin produced by Staphylococci, which are the main microorganisms related to food poisoning cases in the world, requiring studies to trace the sources of contamination during manufacturing and genotypic identification ability of strains to produce enterotoxin. This study aimed to isolate and identify staphylococci positive for coagulase test, potentially producing enterotoxins in dairy products in the state of São Paulo, from milk receiving to final product. In three dairy producers of Minas fresh cheese, samples were collected from various points in the manufacturing process. the technique of mPCR was used to identify three coagulase-positive species (S. aureus, S. hyicus and S. intermedius) between isolates from different points of a processing dairy in the state of São Paulo. The genetic profile of the strains were evaluated by comparing the bands through the technique Enterobacteria Repetitive Intergenic Consensus (ERIC-PCR) and were graphically displayed by a dendrogram. The DNA of 102 strains isolated from samples of raw milk , pasteurized milk , curd, handler and equipment surface from dairies in São Paulo State and cheese were subjected to the polymerase chain reaction (PCR), using primers for the detection of specific fragments of the genes involved in the synthesis of toxins (SE) of type A, B , C , D, E, G , H, I and J. Of the 102 strains tested, five showed amplification of the gene fragment encoding toxin A, three for toxin C , 56 to toxin G, 59 to toxin H, 9 to toxin I, and none for toxins B D, E and J. For confirmation, each isolated strain carrying at least some of the genes related to the production of classical enterotoxinas, cheese and milk samples was subjected to detection by enterotoxigenic VIDAS® Staph Enterotoxin II (VIDAS SET2) bioMérieux. This identification reinforces the need to adopt proper hygiene practices in the dairy, avoiding thus the spread of these microorganisms and the possible production of enterotoxin . The data obtained for the molecular identification of the strains, the occurrence of strains carrying the genes related to the production of enterotoxin production and phenotypic enterotoxins were subjected to the Chi-squared test. This work confirmed that the risk of staphylococcal food poisoning is real, because enterotoxin was found in samples of pasteurized milk and cheeses.

Made available in DSpace on 2014-07-29T15:26:20Z (GMT). No. of bitstreams: 1 Tese Juliana Lamaro completa 2010.pdf: 383347 bytes, checksum: b303674ff0d9eef2f056b5d7aa6a4a91 (MD5) Previous issue date: 2009-04-15 / Objectives: (i) to assess the prevalence of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) nasal carriage in children attending day-care centers (DCC) in the municipality of Goiânia; (ii) to determine the potential risk factors related to S. aureus carriage and MRSA; (iii) to characterize MRSA isolates circulating in DCCs using molecular typing methods. Methods: Between August and December 2005, nasal swabs were collected from children who attended 62 DCCs. Clinical and socio-demographic information associated with the acquisition of S. aureus and MRSA were obtained through questionnaires applied to parents or guardians. The swabs were processed following the standard methods for identification and isolation of S. aureus. Amplification femB gene by polymerase chain reaction (PCR) was used to confirm the specie. The presence of mecA gene was detected by PCR and the positive isolates were identified as MRSA. Susceptibility to MRSA was determined by disk diffusion method. MRSA molecular typing was performed by PFGE, MLST, spa typing and SCCmec multiplex PCR. Results: 371 (31.1%) out of the 1.192 collected swabs were positive for S. aureus and 14 (1.2%) were identified as MRSA. The factors independently associated with risks for nasal colonization by S. aureus were children higher than two years of age (OR = 1.83, 95% CI 1.27-2.65) and previous DCC attendance (OR = 1.48; 95% CI 1.01-2.16). Mother s high degree of education was a protective factor for S. aureus carriage (OR = 0.43, 95% CI 0.23-0.80). A multidrug resistant dominant MRSA lineage was identified comprising 8 out of the 14 MRSA isolates. This cluster was characterized as SCCmec type IIIA, ST239 and spa type t037 sharing 82.7% genetic similarity with the Brazilian clone. One MRSA strain was classified as SCCmec type V and ST1120. This strain showed features of CA-MRSA although it has been recovered from a healthy child who presented risk factors for HA-MRSA acquisition. The remaining MRSA strains showed a diverse genetic background. Conclusions: Children attending DCCs are often colonized with S. aureus and although the prevalence of MRSA was low, they can represent potential vectors of spread of resistant pathogens to the community. The detection of a MRSA lineage circulating within DCCs suggests a two-way flow spread of MRSA between hospitals and community. / Objetivos: (i) avaliar a prevalência de portador nasal de Staphylococcus aureus e S. aureus resistentes à meticilina (MRSA) em crianças que frequentam centros municipais de educação infantil (CMEIs) no município de Goiânia; (ii) determinar os potenciais fatores de risco relacionados com a colonização nasal pelo S. aureus e por MRSA; (iii) caracterizar os isolados de MRSA circulantes nos CMEIS utilizando métodos de tipagem molecular. Material e Métodos: De agosto e dezembro de 2005, swabs nasais foram coletados de crianças menores de cinco anos de idade atendidas em 62 CMEIs do município. Informações clínicas e sócio-demográficas associadas à aquisição de S. aureus e MRSA foram obtidas por meio de questionários aplicados aos pais ou responsáveis. Os swabs foram processados seguindo metodologia padronizada para identificação e isolamento de S. aureus. A confirmação da espécie foi realizada pela amplificaçao do gene femB por reação em cadeia da polimerase (PCR). A presença do gene mecA foi detectada por PCR e os isolados positivos foram identificados como MRSA. O perfil de suscetibilidade para estes isolados foi determinado pelo método de disco difusão. A tipagem molecular dos MRSA foi realizada pelas técnicas de PFGE, MLST, spa typing e SCCmec multiplex PCR. Utilizou-se regressão logística para o cálculo do odds ratio e respectivos intervalos de 95% de confiança. Resultados: Entre os 1.192 swabs coletados, 371 (31,1%) foram positivos para S. aureus e 14 (1,2%) foram identificados como MRSA. Os fatores independentemente associados ao portador nasal de S. aureus foram: crianças acima de dois anos de idade (OR=1,83; IC95% 1,27-2,65) e ter frequentado outra creche (OR= 1,48; IC95% 1,01-2,16). Alto grau de escolaridade da mãe foi um fator protetor para a colonização por S. aureus (OR=0,43; IC95% 0,23-0,80). Uma linhagem genética predominante foi identificada compreendendo 8 dos 14 MRSA isolados. Esta linhagem apresentou perfil de multirresistência, SCCmec tipo IIIA, ST239 e spa type t037, compartilhando 82,7% de similaridade genética com o Clone MRSA Brasileiro. Uma cepa MRSA foi classificada como SCCmec tipo V e ST1120. Esta cepa apresentou características genéticas de MRSA associados à comunidade embora tenha sido recuperada de criança com fatores de risco para aquisição de MRSA relacionado ao serviço de saúde. As demais cepas MRSA apresentaram composição genética bastante diversa. Conclusões: A prevalência de crianças de creches colonizadas pelo S. aureus é alta. Embora a prevalência para MRSA tenha sido baixa nessas crianças, elas representam vetores potenciais de disseminação de MRSA para comunidade. A detecção de uma linhagem de MRSA circulando nos CMEIs e associada a serviços de saúde pode estar sinalizando uma rota de transmissão cruzada destes microrganismos entre hospitais e comunidade.