Clostridium perfringens causa enterite necrótica aviária devido à produção de toxinas que lesam o intestino. Neste estudo, de 94 amostras nove apresentaram C. perfringens, totalizando 22 isolados. Todos exceto um isolado, possuíram os genes nanI (95%) e/ou nanJ (81%), e 19/22, mostraram atividade neuraminidase em hemácias de frango. A atividade hemaglutinante foi observada em poucos isolados (26%). Todos os isolados foram plc positivos (toxina α), sendo classificados como tipo A. Sete isolados (31,8%) abrigaram o gene tpeL que codifica a toxina TpeL. Isolados tpeL+ mostraram efeito citotóxico característico da ação desta toxina. Alguns isolados mostraram capacidade de aderir e invadir células Vero. A maioria dos isolados foi resistente à sulfaquinoxalina (100%), cefalexina (95%) e eritromicina (95%) e sensíveis (100%) à cefoxitina, amoxicilina, enrofloxacina, amoxicilina-ácido clavulânico, penicilina-estreptomicina, cloranfenicol e metronidazol. Todos os isolados foram agrupados geneticamente em sete clusters, apresentando se como um grupo heterogêneo. / Clostridium perfringens cause avian necrotic enteritis due to production of toxins that damage the intestine. In this study, nine out of 94 samples had C. perfringens, totaling 22 isolates. All the isolates with exception of one, possessed the genes nanI (95 %) and/or nanJ (81 %), and 19/22 showed neuraminidase activity in chicken erythrocytes. The hemagglutinating activity was observed in a few isolates (26 %). All isolates were plc positive (toxin α) being classified as type A. Seven isolates (31.8%) harbored tpeL gene encoding the toxin TpeL. TpeL + isolates showed characteristic cytotoxic effect of the action of this toxin. Some isolates showed ability to adhere and invade Hep-2 cells. Most of the isolates were resistant sulphaquinoxaline (100%), cephalexin (95%) and erythromycin (95%) and sensitivity (100%) to cefoxitin, amoxicillin, enrofloxacin, amoxicillin - clavulanic acid, penicillin -streptomycin, chloramphenicol and metronidazole. All isolates were genetically grouped into seven clusters, presenting itself as a heterogeneous group.

Introdução. A pesquisa de Escherichia coli em alimentos é relevante para a Saúde Pública porque indica a contaminação fecal e a qualidade do produto oferecido ao consumidor. A determinação do grupo filogenético e de fatores de virulência de E. coli permite identificar a existência de cepas patogênicas que poderiam causar doença. Objetivos: Determinar o grupo filogenético e fatores de virulência de isolados de E. coli pertencentes aos patotipos ETEC, EIEC, EPEC, STEC e EAEC usando métodos moleculares, obtidos de amostras de queijo Minas, discutir a presença dos patotipos nas amostras e o significado para Saúde Pública. Métodos. 250 isolados de Escherichia coli provenientes de 10 amostras de queijo Minas foram utilizados para a realização do estudo. O DNA genômico foi extraído e neste foi realizado a reação de PCR multiplex. Resultados. Os resultados demonstraram que dos 250 isolados, 93,2% foi classificado como grupo filogenético A, 3,2% como B1, 2,8% como B2 e 0,8% como D. Dos 250 isolados estudados, em 96,8% (242) foram encontrados fatores de virulência, sendo 91,6% de marcadores para ETEC, 0,4% para EPEC e 4,8% para EAEC. Conclusões. Houve predominância de fatores de virulência do patotipo ETEC e do grupo filogenético A. A presença de fatores de virulência indica que as amostras de queijo estavam contaminadas e poderiam causar doença, evidenciando a necessidade de medidas de controle efetivas por parte das autoridades sanitárias, bem como campanhas educativas / Introduction. The search of Escherichia coli in foods is relevant for the Public Health because it indicates the fecal contamination and the product quality offered to the consumer. The determination of phylogenetic group and virulence factors of E. coli, allows the identification of the existence of pathogenic strains that could cause disease. Objectives: Determine the phylogenetic group and the pathogenic of Escherichia coli belonging to the patotipos isolated occurrence ETEC, EIEC, EPEC, STEC and EAEC using molecular methods obtained from Minas cheese samples, to discuss the presence of the patotipos in the samples and the meaning for Public Health. Methods. 250 isolates of Escherichia coli from 10 Minas cheese samples was used for the accomplishment of the study. Genomic DNA was extracted and in this the multiplex reaction PCR was accomplished. Results. The results demonstrated that the isolates 250, 93.2% were classified as phylogenetic group A, 3.2% as B1, 2.8% as B2 and 0.8% as D. Of the isolates 250 studied, in 96.8% (242) were found virulence factors, being 91.6% of markers for ETEC, 0.4% for EPEC and 4.8% for EAEC. Conclusions. There was predominance to virulence factors of the patotipo ETEC and the phylogenetic group A. The presence of virulence factors indicates that the cheese samples were contaminated and they could cause disease, 11 put in evidence the need of effective control measures on the part of the sanitary authorities, as well as educational campaigns.

Em nosso estudo foi avaliada a presença das bactérias do grupo Bacteroides fragilis em 108 amostras fecais de bezerros com e sem diarréia, além de fatores de virulência e a similaridade genética entre as cepas de B. fragilis. Hemolisinas foram observadas em 36,3% e em 83,7% dos bezerros com e sem diarréia, respectivamente. Apenas 7,4% dos isolados foram hemaglutinantes. De todos os isolados, grande parte resistiu à ação do soro e 100% foram sensíveis ao imipenem e metronidazol. Houve resistência aos metais pesados utilizados. Plasmídios foram detectados em 7,4% dos isolados. Dentre 58,8% produtores de ß-lactamase, em 19,7% e em 26,0% de bezerros com e sem diarréia, respectivamente detectou-se o gene cepA, que foi observado também em plasmídios de 5,5 kb. O gene cfiA foi observado em 16,5% dos isolados diarréicos e em 12,6% de não diarréicos, mas não em plasmídios. O gene nanH foi detectado em 21,8% dos isolados e o gene bft somente em dois isolados diarréicos. A similaridadade genética entre os B. fragilis mostrou a heterogeneidade das bactérias. / In this study the bacteria of Bacteroides fragilis group was evaluated in 108 fecal samples of calves with and without diarrhea, besides virulence factors and the genetic similarity among the B. fragilis strains. Hemolysin was observed in 36.3% and in 83.7% of calves with and without diarrhea, respectively. Only 7.4% of the isolates showed hemagglutinability. Of all the isolates, the major part resisted to the action of the serum and 100% were sensitive to the imipenem and metronidazole. There was resistance to the used heavy metals. Plasmids were detected in 7.4% isolates. Among 58.8% ß- lactamase producing, 19.7% and 26.0% strains of calves with and without diarrhea, respectively the cepA gene was detected, that was also observed in 5.5 kb plasmids. The cfiA gene was observed in 16.5% of the diarrheic isolates and 12.6% of non-diarrheic, but not in plasmids. The nanH gene was detected in 21.8% of the isolates and the bft gene only in two diarrheic isolates. The genetic similarity among the B. fragilis showed the heterogeneity of the bacteria.

A classificação de fungos microscópicos é limitada pela escassez de detalhes morfológicos e incertezas na caracterização bioquímica. Nesse trabalho desenvolvemos um método simples, baseado na amplificação de um segmento de cerca de 2.800 bares de bases seguida de digestão com DdeI e análise do padrão após eletroforese em agarose. Demonstramos que o método discrimina tão bem quanto a sequência de DNA do segmento após analisar mais de 400 amostras que foram classificadas em 33 espécies. Essa tecnologia facilita a busca por novos representantes da imensa diversidade existente, espécies que podem ser exploradas quanto ao seu valor potencial para a medicina e a indústria. Outras metodologias moleculares foram desenvolvidas para discriminar entre espécies próximas e na identificação de novas espécies. Em seguida, o trabalho esteve voltado para o desenvolvimento de um ensaio laboratorial que nos permitisse estudar a transição dimórfica em Candida albicans. Desenvolvemos dois novos ensaios, um biológico e outro sobre membrana artificial, para estudar a indução ou inibição da produção de hifas. A expressão de genes associados ao processo foi acompanhada de maneira quantitativa. Fracionando cromatograficamente o soro fetal bovino, obtivemos resultados indicativos de frações estimuladoras e inibidoras da transição morfológica. / Fungal identification is limited by few morphological details and uncertainty in the biochemical tests. In the present work we developed a simple procedure, based upon DNA amplification of a 2,800 base pairs region followed by the amplicon digestion with DdeI and electrophoretic analyzes in agarose gels. After analyzing more than 400 samples encompassing 33 species, we demonstrate that this method discriminates as well as DNA sequencing of the region. This technology simplifies the search for new representatives among the great diversity of fungi of medical and industrial interest. We devised also molecular methods to discriminate between closely related species and described a new putative species. Next our work was dedicated to develop an in vitro assay for the study of the dimorphic transition in Candida albicans. We devised two biological assays and one that used an artificial membrane to investigate the induction and inhibition of hyphal production. The expression of genes associated with the morphological transition was examined in a quantitative way. We fractionated bovine fetal serum by column chromatography and obtained results pointing to fractions that stimulate or inhibit hyphal production.

Neutrophile Granulocyten wirken als einer der ersten Abwehrmechanismen gegen invasive Mikroorganismen im angeborenen Immunsystem von Mammalia. Aktiviert durch inflammatorische Signale verlassen diese Granulocyten das vaskuläre System und migrieren durch das Gewebe zum Infektionsherd. Dort binden sie die Mikroorganismen, phagozytieren und eliminieren diese schließlich mit hoher Effizienz. Humane Neutrophile Elastase (NE) ist Bestandteil der neutrophilen Granula und spielt eine entscheidende Rolle im Abbau von Virulenzfaktoren enteroinvasiver Bakterien, einschließlich der Shigella Virulenzfaktoren IpaB (invasion antigen plasmid B) und IcsA (intracellular spread A). NE gehört zu der Familie der Chymotrypsin-ähnlichen Serinproteasen, die sich durch Sequenz- und Strukurähnlichkeit auszeichnen, jedoch sehr unterschiedliche biologische Funktionen aufweisen. Cathepsin G (CG) ist wie NE eine Chymotrypsin-ähnliche Serinprotease und ebenfalls in neutrophilen Granula lokalisiert. Allerdings zeigt CG keine Aktivität gegenüber Virulenzfaktoren von Shigella. Obwohl die Kristallstrukturen von CG und NE fast identisch sind, konnten einzelne oder mehrere Aminosäuren in der Substratbindungsspalte identifiziert werden, die zwischen den beiden Enzymen differieren. Dies legte die Vermutung nahe, dass die Spezifität von NE gegenüber Virulenzfaktoren in diesen Unterschieden codiert sein könnte. Daher wurden diese Aminosäuren durch die analogen CG Aminosäuren oder durch Alanin ersetzt. Der Vergleich der funktionellen Eigenschaften der NE Mutanten mit wildtyp NE zeigte, dass die Aminosäuren an den Positionen 98 und 216-224 entscheidend für die Substratspezifität von NE sind. Die NE Mutanten N98A, 216-218 und 216-224 waren nicht mehr in der Lage, die Virulenzfaktoren IcsA und IpaB sowie das NE Peptidsubstrat abzubauen. Stattdessen haben diese Mutanten die Fähigkeit erlangt, das CG Peptidsubstrat abzubauen. Zusammenfassend konnten wir Aminosäuren in NE identifizieren, die sowohl die Spezifität von NE für das Peptidsubstrat als auch für die Virulenzfaktoren von Shigella flexneri determinieren. / Neutrophil granulocytes are one of the first lines of defense of the mammalian innate immune system against invading microorganisms. In response to inflammatory stimuli, neutrophils migrate from the blood stream to infected tissues where they bind, engulf and inactivate microorganisms efficiently. Human neutrophil elastase (NE), a neutrophil granule component, is a key host defense protein that rapidly destroys virulence factors of enteroinvasive pathogens including IpaB (invasion plasmid antigen B) and IcsA (intracellular spread A) from Shigella. NE belongs to the family of chymotrypsin-like serine proteases with sequence and structural similarity but with very different biological functions. Cathepsin G (CG) is another abundant chymotrypsin-like serine protease in neutrophil granules. However, in contrast to NE, CG does not cleave virulence factors of Shigella. The crystallographic structures of NE and CG are very similar but we identified single or multiple residues in the substrate-binding cleft to differ in these two enzymes. We hypothesized that NE specificity for bacterial virulence factors resides within these structural differences. Therefore these specific residues in NE were replaced with the analogous amino acids of CG or with alanine. By comparing the functional properties of these NE mutants to wildtype NE we were able to show that the amino acids at position 98 and 216-224 are crucial for the substrate specificity of NE. The NE mutants N98A, 216-218 and 216-224 did not cleave the virulence factors IcsA and IpaB as well as the NE peptide substrate but cleaved the CG peptide substrate. In summary, we identified residues in NE that determine the specificity of NE for the peptide substrate and for the Shigella flexneri virulence factors.

Aggregatibacter actinomycetemcomitans produz fatores de virulência que induzem destruição periodontal, porém a sua regulação é pouco conhecida. O sistema de dois componentes ArcAB é um regulador da transcrição gênica que percebe concentrações de oxigênio no ambiente. Este estudo tem como objetivo construir uma amostra de A. actinomycetemcomitans arcB deficiente e comparar características fenotípicas e de transcrição gênica em relação à amostra selvagem. As curvas de crescimento em condições de microaerofilia e anaerobiose foram similares. Foram observadas diferenças nas capacidades de adesão e invasão às células epiteliais, de formação de biofilme, de adesão à hidroxiapatita recoberta por saliva e na hidrofobicidade entre as amostras. A análise de transcrição gênica por RT-PCR em tempo real mostrou expressão diferenciada de apaH, vppA, vapA e omp29. Os dados indicam que em A. actinomycetemcomitans, ArcB é capaz de detectar condições redox, sendo associado a expressão de fatores de colonização da cavidade oral, regulando a transcrição de genes associados à virulência. / Aggregatibacter actinomycetemcomitans produces several virulence factors which induce periodontal destruction, but little is known about their regulation. The two components system ArcAB is a genetic transcription regulator that senses oxygen concentrations in the environment. This study aimed to construct an A. actinomycetemcomitans arcB deficient mutant and to compare phenotypic carachteristics and gene transcription with the wild type. The growth curves under microaerophilic and anaerobic conditions were similar. There were differences in abilities to adhere and invade epithelial cells, to form biofilm, to adhere to saliva-coated hydroxyapatite and in hydrophobicity between the strains. Gene transcription analysis by real time PCR showed differential expression of apaH, vppA, vapA and omp29. These data indicate that in A. actinomycetemcomitans, ArcB is able to detect redox conditions and is associated with colonization factors of the oral cavity, by regulating transcription of genes associated with virulence.

Les staphylocoques à coagulase négative (SCN) sont généralement considérés comme des pathogènes opportunistes à faible virulence. Cependant, des études antérieures ont rapporté une pathogénicité de certaines souches similaire à celle observée chez S. aureus ce qui laisse supposer l’expression de facteurs de virulence. Cette thèse vise à contribuer à l’importance des SCN dans les infections primitives sévères. Nous avons évalué le potentiel pathogène de souches cliniques de SCN au Bénin. Pour atteindre cet objectif, des SCN associés à diverses infections cliniques sévères ont été collectés sur une période de 10 mois au Centre National Hospitalier et Universitaire Hubert Koutoukou Maga à Cotonou. Ces souches sont identifiées d’abord par la galerie API® Staph, puis par la spectrométrie de masse MALDI-TOF et analysées pour leur susceptibilité aux antibiotiques et leur capacité à produire des facteurs de virulence. Cette partie de l’étude a montré que les espèces les plus impliquées dans les infections à SCN au Bénin sont : S. haemolyticus et S. epidermidis suivi d’autres espèces comme S. cohnii, S. sciuri, S. arlettae, S. capitis. Nous avons aussi apporté la preuve de la multi-résistance des souches aux antibiotiques, ainsi que de la présence d’au moins un, voire plusieurs facteurs de virulence tels que la protéase, l’estérase, l’hémolysine, la leucotoxine et l’entérotoxine staphylococcique C chez 44% des souches testées particulièrement dans les souches hospitalières isolées d’hémocultures. Ensuite, nous avons caractérisé un nouveau facteur de virulence identifié chez deux souches de S. epidermidis : l’entérotoxine staphylococcique C nommée SECepi qui a été dosée à environ 100 µg/mL dans les surnageants de culture bactérienne. Le gène secepi est constitué de 801 pb correspondant à 266 acides aminés. Sur la base des résultats de la comparaison d'homologie entre la chaîne peptidique de SECepi et les séquences déjà connues, nous avons constaté que SECepi est proche de SEC3 de la souche de S. aureus Mu3, avec trois substitutions d'acides aminés dans le peptide signal et neuf substitutions d'acides aminés dans la protéine mature. Cependant, plusieurs résidus qui sont impliqués dans la formation du complexe trimoléculaire CMH-SEC-TCR sont conservés dans SECepi. L’analyse de la protéine recombinante (rSECepi) révèle une parenté antigénique et une forte homologie structurale prédite avec SECaureus. De plus, cette toxine présente les activités biologiques caractéristiques d'un superantigène (SAg) incluant la stimulation de la mitogénicité et de la production concomitante de fortes doses de cytokines pro-inflammatoires et suppressives chez des lymphocytes T humains activés. Par ailleurs, SECepi résiste assez bien au chauffage à 100°C et à la digestion par les enzymes gastro-intestinales telles que la pepsine et la trypsine. Ces résultats fournissent la preuve que SECepi peut agir comme un superantigène chez l'hôte humain bien que le type sauvage comporte plusieurs mutations chez S. epidermidis. L’étude du dossier médical de l’un des patients a montré que l’entérotoxine produite par la souche de S. epidermidis a bien pu être à l’origine d’éléments de gravité du tableau clinique présenté par ce dernier à son admission en hospitalisation. Enfin, l’analyse génomique des deux souches toxinogènes de S. epidermidis, ainsi que leur aptitude à former du biofilm, confirment les possibilités variées d’échanges génétiques entre cette espèce et S. aureus. Cette thèse souligne l'importance de la surveillance des infections à SCN chez l’homme parce que certaines souches, à l’instar de S. aureus, produisent des facteurs de virulence pouvant aggraver l’état générale l’hôte. / Coagulase-negative staphylococci (CNS) are generally considered as opportunistic pathogens with low virulence. However, previous studies have reported pathogenicity of some strains similar to that observed in S. aureus. This thesis aims to contribute to the importance of SCN in severe primitive infections. First, we evaluated the pathogenic potential of clinical CNS strains in Benin. To achieve this objective, CNS associated with various severe clinical infections were collected over at the Hubert Koutoukou Maga National Hospital and University Center in Cotonou. These strains are identified as well as their susceptibility to antibiotics and their ability to produce virulence factors. This part of the study showed that the most involved species in Benin are: S. haemolyticus and S. epidermidis followed by other species such as S. cohnii, S. sciuri, S. arlettae, S. capitis. We also demonstrated the multi-resistance of strains to antibiotics, as well as the presence of potential virulence factors such as protease, esterase, hemolysin, leukotoxin and, enterotoxin Staphylococcal C in 44% of strains tested particularly in hospital strains isolated from blood cultures. We, then, characterized a new virulence factor identified in two strains of S. epidermidis: staphylococcal enterotoxin C called SECepi, which was secreted at ~100 μg/mL in bacterial culture supernatants. The secepi gene consists of 801 bp corresponding to 266 amino acids. On the basis of the comparison between the peptide chain of SECepi and the already known peptide sequences of the SEC, we found that SECepi is close to SEC3 of S. aureus Mu3 strain with three amino acids substitutions in the signal peptide and nine amino acid substitutions in the mature protein. However, most residues involved in formation of the tri-molecular complex CMH-SEC-TCR are conserved in SECepi. Analysis of the recombinant protein (rSECepi) revealed antigenic relationships and a strong structural homology is predicted with SECaureus. Moreover, this toxin exhibits the biological activities characteristic of a SAg including the stimulation of the mitogenicity and the concomitant production of high doses of pro-inflammatory and suppressive cytokines in activated human T lymphocytes. Moreover, SECepi is resistant to heating at 100 °C and digestion by gastrointestinal enzymes such as pepsin and trypsin. These results provide evidence that SECepi can act as a superantigen in humans although the wild type has several mutations in S. epidermidis. The study of the medical record of one of the patients showed that the enterotoxin produced by the strain of S. epidermidis might be at the origin of severity of the clinics presented at hospital admission. Finally, genomic analysis of the two toxigenic S. epidermidis strains confirms the varied possibilities of genetic exchange between this species and S. aureus. This thesis underscores the importance of monitoring CNS infections in humans because some strains, like S. aureus, produce virulence factors that can aggravate the overall host condition.

Escherichia coli foi isolado de amostras de água de lastro, água de regiões portuárias e de bivalves. 49,6% (164/331) apresentaram múltipla resistência variando de 2 a 8 antibióticos. Dos sete fatores associados à virulência pesquisados: Toxina termoestável (ST), Toxina termolábil (LT), Adesão agregativa (EAEC), Fator de invasão (INV), Toxina Shiga-like I (stx-1), Toxina Shiga-like II (stx-2), e o gene intimina (eae): 4 isolados continham genes homólogos para EAEC, 3 para eae, 3 para ST e uma para stx-2. Um total de 80,0% (24/30), 72,3% (68/94) e 75,3% (55/73) dos isolados de E. coli de amostras de água de lastro, água de regiões portuárias e moluscos bivalves apresentaram plasmídeos, respectivamente. O método ERIC-PCR apresentou melhor desempenho para a análise de agrupamentos. Os isolados de E. coli, com as características encontradas, nos permitirá avaliar o perigo de sua presença no ambiente marinho costeiro e na água de lastro e programas de vigilância sanitária devem ser implementadas para proteger a saúde humana, animal e do ecossistema marinho. / Escherichia coli was isolated from ballast water, port areas water and bivalves samples. 49.6% (164/331) had multiple antibiotics resistant varied from 2 to 8 antibiotics. From seven virulence associated factors investigated: heat stable toxin (ST), heat labile toxin (LT), aggregative adhesion (EAEC), invasion factor (INV), Shiga-like I toxin (STx-1), Shiga-like II toxin (STx-2), and the gene that codify for intimin (eae): 4 isolates had homology to the EAEC, 3 for eae gene, 3 for ST and one for stx2. A total of 80.0% (24/30), 72.3% (68/94) and 75.3% (55/73) of E. coli isolates from ballast water, port area water and bivalves samples had plasmids, respectively. The ERIC-PCR was more efficiency to analyze the groups. The presence of E. coli isolates with the characteristics found will allow evaluate the hazard present at the coast area ecosystem and ballast water samples and sanitary surveillance programs must be implemented for human, animal and aquatic ecosystem health protection.

Para determinar a prevalência e epidemiologia dos enteropatógenos bacterianos e parasitários na diarréia aguda infantil, foram estudadas 290 crianças menores de 24 meses com diarréia e 290 crianças controles, que procuraram o serviço de emergência do Hospital Infantil Arlinda Marques em João Pessoa, Nordeste do Brasil. Enteropatógenos foram identificados em 78,2% dos casos e em 12,4% dos controles; Escherichia coli enteroagregativa (EAEC) foi o patógeno mais freqüente sendo detectada em 25% dos casos e em 8,3% dos controles; seguida por E. coli enteropatogênica (EPEC) em 11% dos casos (dos quais 9,3% foram cepas atípicas) e em 0,3% dos controles; E. coli Enterotoxigência (ETEC) em 10% dos casos e 2,8% dos controles; Salmonella sp em 7,9% dos casos; Shigella sp em 4,1% dos casos; E. coli enteroinvasora (EIEC) em 1,7% dos casos; Campylobacter sp em 2,4% dos casos e enteroparasitas foram detectados em 15,5% dos casos e 1,0% dos controles. Infecções mistas foram verificadas em 32 (11%) casos e em apenas 1 (0,3%) controle. A faixa etária mais atingida foi a dos menores de um ano e as associações mais frequentes ocorreram entre EAEC + Salmonella e EAEC + EPEC atípica. Neste estudo foram identificados fatores de risco associados com episódios de diarréia em crianças de acordo com o agente etiológico bacteriano. As análises estatísticas demonstram uma importante associação de EAEC com diarreia aguda infantil em João Pessoa, Brasil, sendo a ingestão de leite de vaca em pó e a exposição a aglomerados e creche os fatores de risco mais associados a diarreia causada por EAEC. / In order to determine the prevalence and epidemiology of enteropathogens in acute infantile diarrhoea, 290 infants younger than 24 months of age with diarrhoea and 290 age-matched control subjects who came to ER of the Hospital Infantil Arlinda Marques in João Pessoa, Northeastern of Brazil were studied. Enteropathogens were identified in 78,2% of case infants and 12,4% of controls. Enteroagregative Escherichia coli (EAEC) was the most frequently found pathogen and was detected in 25,0% of cases and 8,3% of controls. The second most frequent pathogen was Enteropathogenic E. coli (EPEC), in 11,0% of cases and 0,3% of controls, followed by Enterotoxigenic E. coli (ETEC) in 10% of cases and 2,7% of controls; Salmonella sp was found in 7,9% of cases, Shigella sp in 4,1% of cases, Enteroinvasive E. coli (EIEC) in 1,7% of cases and Campylobacter sp in 2,4% of cases. Enteroparasites were detected in 15,5% of cases and 1,0% of controls. Mixed infections (more than one pathogen) were found in 32 (11%) of cases and in only 1 (0,3%) control. The most affected age group was of those smaller than 1 year of age and the most frequent associations were of EAEC + Salmonella e EAEC + atypical EPEC. In this study risk factors associated with episodes of diarrhoea among infants by bacterial etiological pathogens were identified. Statistical analysis demonstrated a significant association of Enteroagregative E. coli (EAEC) with acute infantile diarrhoea in João Pessoa, Brazil. The risk factors most strongly associated diarrhoea caused by EAEC were the ingestion of powdered cow milk and exposure to crowds and day care centres.

Aggregatibacter actinomycetemcomitans (A.a) é associado a periodontite agressiva. Na infecção, pode ocorrer ativação de vias de sinalização do hospedeiro e bacterianas. Objetivos: determinar a transcrição de genes relacionados à virulência bacteriana e das vias de transdução de sinais da célula epitelial após interação bactéria-célula epitelial. Métodos: cepas de A.a foram co-cultivadas com células epiteliais OBA-9. A transcrição dos genes bacterianos e das células epiteliais foi determinada por RT-qPCR e a concentração de citocinas determinada por ELISA. Resultados: A regulação da transcrição de certos genes de virulência de A.a é cepa e tempo específica. Quinze genes foram regulados positivamente nas células OBA-9 infectadas. Altos níveis de GM-CSF, TNF-<font face=\"Symbol\">&#945 e ICAM-1 foram detectados em células OBA-9 infectadas e tecidos gengivais de pacientes com periodontite. Conclusão: a interação entre A. a e célula epitelial pode modular a resposta do hospedeiro com a indução da expressão de fatores que exacerbam o processo inflamatório. / Aggregatibacter actinomycetemcomitans (A.a) is associated with the etiology of aggressive periodontitis. The activation of signaling pathways by the host and bacterial cells occurs during infection. Objectives: to determine the transcription of genes related to bacterial virulence and epithelial cell after bacterial-epithelial cell interaction. Methods: A.a strains were co-cultured with epithelial cells OBA-9. The transcription of A.a virulence genes and genes belonging to signaling transduction pathway were determined by RT-qPCR and the concentration of cytokines was determined by ELISA. Results: the transcription of some virulence genes is strain and time specific. Fifteen genes were up-regulated in OBA-9 cells. High levels of GM-CSF, TNF-<font face=\"Symbol\">&#945 and ICAM-1 were detected in infected OBA-9 cells and tissues of patients with periodontitis. Conclusion: the interaction between A.a and epithelial cell can modulate the host response with induction of factors which exacerbate inflammatory process.