Effect of pH in the survival of Lactobacillus salivarius strain UCO_979C wild type and the pH acid acclimated variant

Background: Bacterial acclimation involves cellular changes permitting the survival of a microorganism to prolonged acid pH exposure. The general aim of this work is to support this idea by determining the effect of pH in the survival of the human gastric derived probiotic strain Lactobacillus salivarius UCO_979C-1 (wild type) and L. salivarius UCO_979C-2 (acclimation to pH 2.6), which possesses anti- Helicobacter pylori properties. Results: To assess this aim, the exopolysaccharide production through the phenol-sulfuric acid method was evaluated. Moreover, morphological and structural changes by transmission and scanning electron microscopy were observed. The bacterial survival was measured by viable count. The results showed that the acclimated variant strain synthesized higher levels of exopolysaccharide (690 \ub1 0.03 mg/L) more than the wild type (450 \ub1 0.12 mg/L). In addition, the acclimated variant preserved the viable count at pH 2.6 for 48 h, whereas the wild type strain decreases after 6 h and was non-viable at 24 h. Conclusion: The results suggest that the acid stress acclimation of the strain L. salivarius UCO_979C-1 modified some cellular properties making this strain potentially useful as a gastric probiotic

Phenotypic and genotypic antimicrobial resistance in Escherichia coli strains isolated from household dogs in Chile

IntroductionAntimicrobial resistance (AMR) is a major threat to animal and public health worldwide; consequently, several AMR surveillances programs have been implemented internationally in both human and veterinary medicine, including indicator bacteria such as Escherichia coli. However, companion animals are not typically included in these surveillance programs. Nevertheless, there have been reports of increasing levels of antimicrobial resistance in E. coli strains isolated from dogs worldwide. In Chile, there is limited information available on AMR in E. coli isolated from companion animals, which prevents the establishment of objective prevention and control measures.MethodsFor this reason, the aim of this study was to characterize the phenotypic and genotypic AMR of E. coli strains isolated from healthy household dogs in Chile. For this purpose, a multi-stage sampling was carried out in the Metropolitan Region of Chile, obtaining samples from 600 healthy dogs. These samples were processed using traditional bacteriology and molecular techniques to isolate E. coli strains. We assessed the minimal inhibitory concentration of 17 antimicrobials and conducted a search of six antimicrobial resistance genes, as well as class 1 and 2 integrons, in the isolated strains.ResultsTwo-hundred and twenty-four strains of E. coli were recovered, and 96.9% (n = 217) showed resistance to at least one drug and only 3.1% (n = 7) were susceptible to all analyzed antimicrobials. Most strains were resistant to cefalexin (91.5%, n = 205, 1st-generation cephalosporin), followed by ampicillin (68.3%, n = 153) and cefpodoxime (31.3%, n = 70, 3rd-generation cephalosporin). Moreover, 24.1% (n = 54) tested positive for extended-spectrum-β-lactamases and 34.4% (n = 77) were multidrug resistant. As for the AMR genes, the most detected was qnrB (28.1%, n = 63), followed by blaCTX-M (22.3%, n = 50), and blaTEM-1 (19.6%, n = 44). Additionally, 16.1% (n = 36) harbored class 1 integrons. Our study shows that E. coli strains isolated from healthy household dogs exhibit resistance to several relevant drugs and also antimicrobial resistance genes considered critical for human health. These results can be used as a starting point for the prevention and control of antimicrobial resistance from companion animals. This background should be considered when formulating future resistance surveillance programs or control plans in which companion animals must be included

A novel virulence strategy for Pseudomonas aeruginosa mediated by an autotransporter with arginine-specific aminopeptidase activity

The opportunistic human pathogen, Pseudomonas aeruginosa, is a major cause of infections in chronic wounds, burns and the lungs of cystic fibrosis patients. The P. aeruginosa genome encodes at least three proteins exhibiting the characteristic three domain structure of autotransporters, but much remains to be understood about the functions of these three proteins and their role in pathogenicity. Autotransporters are the largest family of secreted proteins in Gram-negative bacteria, and those characterised are virulence factors. Here, we demonstrate that the PA0328 autotransporter is a cell-surface tethered, arginine-specific aminopeptidase, and have defined its active site by site directed mutagenesis. Hence, we have assigned PA0328 with the name AaaA, for arginine-specific autotransporter of P. aeruginosa. We show that AaaA provides a fitness advantage in environments where the sole source of nitrogen is peptides with an aminoterminal arginine, and that this could be important for establishing an infection, as the lack of AaaA led to attenuation in a mouse chronic wound infection which correlated with lower levels of the cytokines TNFα, IL-1α, KC and COX-2. Consequently AaaA is an important virulence factor playing a significant role in the successful establishment of P. aeruginosa infections

Campo Experimental Potrok Aike : resultado de 15 años de labor técnica

Libro de edición impresa publicado en 2005 y con edición electrónica en el año 2016.Al crearse, en el año 1985, la Estación Experimental Santa Cruz en el marco del convenio entre el INTA y la provincia de Santa Cruz surgió la necesidad de contar con un campo donde se pudieran desarrollar trabajos de investigación en ganadería, fundamentalmente ovina, y en pastizales naturales con el necesario control de diferentes variables productivas y ambientales. El gobierno provincial cedió un predio ubicado al sur de la provincia de Santa Cruz, en una zona representativa de la Estepa magallánica seca, en el extremo austral de la Patagonia. Esta publicación recopiló y organizó los datos e información dispersa resultante de más de 15 años de trabajo, y transformó esa materia prima en información accesible para técnicos y productores. Conformada por el aporte de distintos autores ofrece la información de base para describir el ambiente del Campo Experimental Potrok Aike, más las conclusiones de ensayos y experiencias llevadas a cabo en el lugar, que son perfectamente extrapolables a todo el sur provincial.EEA Santa CruzFil: Alegre, María Beatriz. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Alegre, María Beatriz. Consejo Agrario Provincial- Provincia de Santa Cruz; Argentina.Fil: Alegre, María Beatriz. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; ArgentinaFil: Anglesio, Francisco. Secretaría de Medio Ambiente. Provincia de Santa Cruz. Santa Cruz; Argentina.Fil: Baetti, Carlos. Consejo Agrario Provincial- Provincia de Santa Cruz; Argentina.Fil: Baetti, Carlos. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Bahamonde, Héctor Alejandro. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Bahamonde, Héctor Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; ArgentinaFil: Barría, Julio. Consejo Agrario Provincial- Provincia de Santa Cruz; Argentina.Fil: Battini, Alberto. Consejo Agrario Provincial- Provincia de Santa Cruz; Argentina.Fil: Baumann, Osvaldo. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Borrelli, Pablo. Consultor privado. Buenos Aires; Argentina.Fil: Camejo, Ana María. Consultor privado. Trelew; Argentina.Fil: Castillo, Miguel. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Cibils, Andrés. New México State University. Department of Animal and Range Sciences; Estados UnidosFil: Ciurca, Lorena. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Clifton, Guillermo Raimundo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Clifton, Guillermo Raimundo. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Culun, Victor Pascual. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; ArgentinaFil: Escalada, Julián. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Ferrante, Daniela. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; ArgentinaFil: Ferrante, Daniela. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Gismondi, Daniel. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: González, Liliana. Consejo Agrario Provincial- Provincia de Santa Cruz; Argentina.Fil: Grima, Daniel. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Humano, Gervasio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; ArgentinaFil: Iacomini, Mónica. Secretaría de la Producción. Provincia de Santa Cruz. Santa Cruz; Argentina.Fil: Iglesias, Roberto. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Chubut; Argentina.Fil: Kofalt, Bustamante Rosa. Consejo Agrario Provincial- Provincia de Santa Cruz; Argentina.Fil: Kofalt, Bustamante Rosa. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Kofalt, Bustamante Rosa. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Lamoureux, Mabel Noemi. Consejo Agrario Provincial- Provincia de Santa Cruz; Argentina.Fil: Lamoureux, Mabel Noemi. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; ArgentinaFil: Larrosa, José. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; ArgentinaFil: Manero, Amanda. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Manero, Amanda. Consejo Agrario Provincial- Provincia de Santa Cruz; Argentina.Fil: Marcolín, Arrigo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; Argentina.Fil: Mascó, Mercedes. Consejo Agrario Provincial- Provincia de Santa Cruz; Argentina.Fil: Mascó, Mercedes. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Mascó, Mercedes. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Migliora, Horacio. Consejo Agrario Provincial- Provincia de Santa Cruz; Argentina.Fil: Milicevic, Francisco. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; ArgentinaFil: Montes, Leopoldo. Instituto Nacional de Tecnología Agropecuaria (INTA). Centro Regional Patagonia Sur; Argentina.Fil: Oliva, Gabriel Esteban. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Oliva, Gabriel Esteban. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Osses, Julio Angel. Consejo Agrario Provincial- Provincia de Santa Cruz; Argentina.Fil: Paredes, Paula. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peinetti, Raúl. Universidad Nacional de La Pampa. Facultad de Agronomía; Argentina.Fil: Rial, Pablo Eduardo. Ministerio de Economía y Obras Públicas. Provincia de Santa Cruz; Argentina.Fil: Rial, Pablo Eduardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Romero, Rubén. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Rosales, Valeria. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Salazar, Daniel. LU85 TV Canal 9. Auxiliar en Control de Erosión de Suelos. Provincia de Santa Cruz; Argentina.Fil: Tapia, Hector Horacio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Chubut; Argentina.Fil: Torra, Francisco. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.Fil: Zerpa, Débora. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina

Electronic Journal of Biotechnology Effect of pH in the survival of Lactobacillus salivarius strain UCO_979C wild type and the pH acid acclimated variant

Effect of pH in the survival of Lactobacillus salivarius strain UCO_979C wild type and the pH acid acclimated variant Electronic Journal of Biotechnology, vol. 18, núm. 5, 2015, pp. 343-346 Pontificia Universidad Católica de Valparaíso Valparaíso, Chile Background: Bacterial acclimation involves cellular changes permitting the survival of a microorganism to prolonged acid pH exposure. The general aim of this work is to support this idea by determining the effect of pH in the survival of the human gastric derived probiotic strain Lactobacillus salivarius UCO_979C-1 (wild type) and L. salivarius UCO_979C-2 (acclimation to pH 2.6), which possesses anti-Helicobacter pylori properties. Results: To assess this aim, the exopolysaccharide production through the phenol-sulfuric acid method was evaluated. Moreover, morphological and structural changes by transmission and scanning electron microscopy were observed. The bacterial survival was measured by viable count. The results showed that the acclimated variant strain synthesized higher levels of exopolysaccharide (690 ± 0.03 mg/L) more than the wild type (450 ± 0.12 mg/L). In addition, the acclimated variant preserved the viable count at pH 2.6 for 48 h, whereas the wild type strain decreases after 6 h and was non-viable at 24 h. Conclusion: The results suggest that the acid stress acclimation of the strain L. salivarius UCO_979C-1 modified some cellular properties making this strain potentially useful as a gastric probiotic

Effect of pH in the survival of Lactobacillus salivarius strain UCO_979C wild type and the pH acid acclimated variant

Background: Bacterial acclimation involves cellular changes permitting the survival of a microorganism to prolonged acid pH exposure. The general aim of this work is to support this idea by determining the effect of pH in the survival of the human gastric derived probiotic strain Lactobacillus salivarius UCO_979C-1 (wild type) and L. salivarius UCO_979C-2 (acclimation to pH 2.6), which possesses anti-Helicobacter pylori properties. Results: To assess this aim, the exopolysaccharide production through the phenol-sulfuric acid method was evaluated. Moreover, morphological and structural changes by transmission and scanning electron microscopy were observed. The bacterial survival was measured by viable count. The results showed that the acclimated variant strain synthesized higher levels of exopolysaccharide (690 ± 0.03 mg/L) more than the wild type (450 ± 0.12 mg/L). In addition, the acclimated variant preserved the viable count at pH 2.6 for 48 h, whereas the wild type strain decreases after 6 h and was non-viable at 24 h. Conclusion: The results suggest that the acid stress acclimation of the strain L. salivarius UCO_979C-1 modified some cellular properties making this strain potentially useful as a gastric probiotic

Virulence Genes, Shiga Toxin Subtypes, Serogroups, and Clonal Relationship of Shiga Toxin-Producing Escherichia Coli Strains Isolated from Livestock and Companion Animals

Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen that causes severe illness in humans and is an important cause of foodborne disease. In Chile, there is limited information on the virulence characteristics of this pathogen in livestock, and none in companion animals. The aim of this study was to characterize STEC strains isolated from cattle, swine, dogs, and cats, in Chile, in terms of the presence of Shiga toxin types and subtypes, virulence genes, serogroups, and clonality. One-thousand two-hundred samples were collected, isolating 54 strains (4.5%), where stx1a (68.5%) and ehxA (74.1%) were the most frequently detected virulence genes. Only one strain belonging to the most clinically relevant serogroups was identified. Pulsed field gel electrophoresis analysis showed high clonal diversity among strains isolated from cattle, while those from swine showed the same pattern. This study provides further evidence regarding cattle and swine in Chile as a potential source of a wide variety of STEC strains that could potentially cause severe illness in humans, and that companion animals do not seem to represent a relevant reservoir. It also argues that preventive and control strategies should not be focused on detecting serogroups, but instead, on detecting their determinants of virulence

Phenotypic and genotypic antimicrobial resistance in non-O157 Shiga toxin-producing Escherichia coli isolated from cattle and swine in Chile

Non-O157 Shiga toxin-producingEscherichia coli(STEC) is a zoonotic pathogen that causes bloody diarrhea and hemolytic-uremic syndrome in humans, and a major cause of foodborne disease. Despite antibiotic treatment of STEC infections in humans is not recommended, the presence of antimicrobial-resistant bacteria in animals and food constitutes a risk to public health, as the pool of genes from which pathogenic bacteria can acquire antibiotic resistance has increased. Additionally, in Chile there is no information on the antimicrobial resistance of this pathogen in livestock. Thus, the aim of this study was to characterize the phenotypic and genotypic antimicrobial resistance of STEC strains isolated from cattle and swine in the Metropolitan region, Chile, to contribute relevant data to antimicrobial resistance surveillance programs at national and international level. We assessed the minimal inhibitory concentration of 18 antimicrobials, and the distribution of 12 antimicrobial resistance genes and class 1 and 2 integrons in 54 STEC strains. All strains were phenotypically resistant to at least one antimicrobial drug, with a 100% of resistance to cefalexin, followed by colistin (81.5%), chloramphenicol (14.8%), ampicillin and enrofloxacin (5.6% each), doxycycline (3.7%), and cefovecin (1.9%). Most detected antibiotic resistance genes weredfrA1 andtetA (100%), followed bytetB (94.4%),bla(TEM-1)(90.7%),aac(6)-Ib(88.9%),bla(AmpC)(81.5%),cat1 (61.1%), andaac(3)-IIa(11.1%). Integrons were detected only in strains of swine origin. Therefore, this study provides further evidence that non-O157 STEC strains present in livestock in the Metropolitan region of Chile exhibit phenotypic and genotypic resistance against antimicrobials that are critical for human and veterinary medicine, representing a major threat for public health. Additionally, these strains could have a competitive advantage in the presence of antimicrobial selective pressure, leading to an increase in food contamination. This study highlights the need for coordinated local and global actions regarding the use of antimicrobials in animal food production.Comisión Nacional de Investigación Científica y Tecnológica (CONICYT) CONICYT FONDECYT 1117036

The passenger and β-barrel domains of AaaA remain connected and are tethered to the cell surface.

<p><i>E. coli</i> LEMO21 bearing the empty vector pET21a or pET21a::<i>aaaA</i> was grown to mid exponential phase in LB, and induced with 1 mM IPTG for 1 h. Following harvesting, washing and resuspension in PBS-Hepes, half of the cells were lysed by sonication. The whole and lysed cells were split into three aliquots and incubated with (T) or without (−) trypsin according to the <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1002854#s4" target="_blank">Materials and Methods</a>. Trypsin inhibitor was added at the same time as trypsin to one of the aliquots (T+I). Proteins were separated through a 9% SDS PAGE and stained with Coomassie Blue (Panel A) or subjected to immunoblotting with either α-AaaA (Panel B, top), or α-IscS (Panel B, bottom) antisera. A parallel experiment was performed with <i>P. aeruginosa</i> Δ<i>aaaA</i> bearing either pME6032 or pME6032::<i>aaaA</i>. LB overnight cultures were diluted 1∶100 in fresh LB, grown for 3 h at 37°C, and induced with 1 mM IPTG for 1 h. The immunoblot of the <i>P. aeruginosa</i> proteins is shown in Panel C, with the cytoplasmic control protein being detected with α-RpoS in the bottom panel. The sizes of molecular weight markers are shown in kDa on the left, and the position of AaaA is indicated. In Panels B and C, densitometry was used to estimate the quantity of the cytoplasmic protein and the full length AaaA (indicated with the asterisk) detected in the immunoblots using imageJ software. The fold change of AaaA, IscS and RpoS are shown below the images of the respective immunoblots. The images in Panels D and E were captured by confocal fluorescent microscopy. <i>P. aeruginosa</i> Δ<i>aaaA</i>(pME6032::<i>aaaA</i>) was grown and induced as described for Panel C, probed with FM1-43 and either α-AaaA (Panel E) or pre-immune serum (Panel D). Incubation with donkey α-rabbit alexa fluor 680-conjugated secondary antibody (red) was performed before images were captured at either the apex or cross section of individual cells (as indicated in the dotted lines of the cartoon). Green fluorescence from FM1-43 (top Panel, green circle in cartoon), red fluorescence from alexa fluor 680 (middle Panel, red stars in cartoon), merged 2D and merged 3D shadowed images are shown.</p