b Shiga-toxin producing Escherichia coli (STEC) is the etiologic agent of acute diarrhea, dysentery, and hemolytic-uremic syndrome (HUS). There is no approved vaccine for STEC infection in humans, and antibiotic use is contraindicated, as it promotes Shiga toxin production. In order to identify STEC-associated antigens and immunogenic proteins, outer membrane proteins (OMPs) were extracted from STEC O26:H11, O103, O113:H21, and O157:H7 strains, and commensal E. coli strain HS was used as a control. SDS-PAGE, two-dimensional-PAGE analysis, Western blot assays using sera from pediatric HUS patients and controls, and matrix-assisted laser desorption ionization-tandem time of flight analyses were used to identify 12 immunogenic OMPs, some of which were not reactive with control sera. Importantly, seven of these proteins have not been previously reported to be immunogenic in STEC strains. Among these seven proteins, OmpT and Cah displayed IgG and IgA reactivity with sera from HUS patients. Genes encoding these two proteins were present in a majority of STEC strains. Knowledge of the antigens produced during infection of the host and the immune response to those antigens will be important for future vaccine development.
Background: Little is known about the interaction between the nasopharyngeal bacterial profile and the nutritional status in children. In this study, our main goal was to evaluate the associations between overnutrition and the presence of four potentially pathogenic bacteria in the nasopharynx of infants with viral lower respiratory tract infections (LRTI). In addition, we determined whether changes in the nasopharyngeal bacterial profile were associated with mucosal and serum proinflammatory cytokines and with clinical disease severity. Methods: We enrolled 116 children less than 2 years old hospitalized for viral LRTI during two consecutive respiratory seasons (May 2016 to August 2017); their nutritional status was assessed, and nasopharyngeal and blood samples were obtained. S. aureus, S. pneumoniae, H. influenzae, M. catarrhalis, and respiratory viruses were identified in nasopharyngeal samples by qPCR. Cytokine concentrations were measured in nasopharyngeal and blood samples. Disease severity was assessed by the length of hospitalization and oxygen therapy. Results: Nasopharyngeal pathogenic bacteria were identified in 96.6% of the enrolled children, and 80% of them tested positive for two or more bacteria. The presence and loads of M. catarrhalis was higher (p = 0.001 and p = 0.022, respectively) in children with overnutrition (n = 47) compared with those with normal weights (n = 69). In addition, the detection of >2 bacteria was more frequent in children with overnutrition compared to those with normal weight (p = 0.02). Multivariate regression models showed that the presence and loads of S. pneumoniae and M. catarrhalis were associated with higher concentrations of IL-6 in plasma and TNF-α in mucosal samples in children with overnutrition. Conclusions: The nasopharyngeal profile of young children with overnutrition was characterized by an over representation of pathogenic bacteria and proinflammatory cytokines.
La disminución sostenida de la disponibilidad de nuevas moléculas antimicrobianas para el uso terapéutico en las últimas décadas y el gran aumento de microorganismos resistentes a estos compuestos hace necesario buscar nuevas sustancias con propiedades antimicrobianas. Los ambientes extremos, donde hay poca disponibilidad de nutrientes, son escenarios propicios para buscar este tipo de compuestos, ya que las bacterias compiten entre sí y con otros organismos por posicionarse en el nicho ecológico y secretan, asociado a su metabolismo secundario, una serie de moléculas que inhiben o matan a otros microorganismos, evitando su multiplicación. Nuestro grupo posee una colección de bacterias aisladas de la rizósfera de suelo del continente antártico, que logran crecer en condiciones de deprivación alimenticia y a 4 ºC. Debido al hábitat extremo donde se desarrollan, las bacterias de los suelos de la Antártica están en una constante competencia por lo recursos nutricionales, desarrollando distintas estrategias para colonizar su nicho ecológico y competir con otros microorganismos de la microbiota Antártica. En base a lo anterior, el objetivo de este trabajo consistió en identificar bacterias aisladas de la rizosfera de Deschampsia antarctica Desv capaces de inhibir no solo el crecimiento de microorganismos de su entorno, sino que también de bacterias y hongos patógenos para humanos. A partir de una colección de 55 aislados de la rizósfera de la planta D. antarctica Desv. se identificó 11 aislados con capacidad de matar o inhibir bacterias patógenas humanas pero ningún aislado inhibió el crecimiento del hongo Candida albicans. Los resultados mostraron que las 11 bacterias antárticas con actividad antibacteriana corresponden a bacilos aerobios estrictos, Gram negativo, con características de pertenecer al género Pseudomonas.
We announce the draft genome sequence of Pseudomonas sp. strain K2I15, isolated from the rhizosphere of Deschampsia antarctica Desv. The genome sequence had 6,645,031 bp with a G+C content of 60.4%. This genome provides insights into the niche adaptation, prophage carriage, and evolution of this specific Antarctic bacteria.
We present here the draft genome sequence of Bacillus sp. strain K2I17, which was isolated from the rhizosphere of Deschampsia antarctica Desv. The genomic sequence contained 6,113,341 bp. This genome provides insights into the possible new biomedical and biotechnical applications of this specific Antarctic bacterium.
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