Defence strategies and antibiotic resistance gene abundance in enterococci under stress by exposure to low doses of peracetic acid

partially_open12noPeracetic acid (PAA) is an organic compound used efficiently as disinfectant in wastewater treatments. Yet, at low doses it may cause selection; thus, the effect of low doses of PAA on Enterococcus faecium as a proxy of human-related microbial waste was evaluated. Bacteria were treated with increasing doses of PAA (from 0 to 25 mg L1 min) and incubated in regrowth experiments under non-growing, limiting conditions and under growing, favorable conditions. The changes in bacterial abundance, in bacterial phenotype (number and composition of small cell clusters), and in the abundance of an antibiotic resistance gene (ARG) was evaluated. The experiment demonstrated that the selected doses of PAA efficiently removed enterococci, and induced a long-lasting effect after PAA inactivation. The relative abundance of small clusters increased during the experiment when compared with that of the inoculum. Moreover, under growing favorable conditions the relative abundance of small clusters decreased and the number of cells per cluster increased with increasing PAA doses. A strong stability of the measured ARG was found, not showing any effect during the whole experiment. The results demonstrated the feasibility of low doses of PAA to inactivate bacteria. However, the stress induced by PAA disinfection promoted a bacterial adaptation, even if potentially without affecting the abundance of the ARG.openTurolla, Andrea; Sabatino, Raffaella; Fontaneto, Diego; Eckert, Ester M.; Colinas, Noemi; Corno, Gianluca; Citterio, Barbara; Biavasco, Francesca; Antonelli, Manuela; Mauro, Alessandro; Mangiaterra, Gianmarco; Di Cesare, AndreaTurolla, Andrea; Sabatino, Raffaella; Fontaneto, Diego; Eckert, Ester M.; Colinas, Noemi; Corno, Gianluca; Citterio, Barbara; Biavasco, Francesca; Antonelli, Manuela; Mauro, Alessandro; Mangiaterra, Gianmarco; Di Cesare, Andre

Aula de innovación educativa

La formación de jóvenes agentes en educación para la salud confirma la importancia que tiene la formación de éstos para favorecer un mayor compromiso en la prevención de otros jóvenes, así como para facilitar estilos de vida responsables. La Universidad Pablo de Olavide y la Junta de Andalucía mantienen un convenio que tiene por objeto la definición y el establecimiento de actuaciones informativas, formativas, investigadoras y de prevención de las drogodependencias. En este artículo se muestran los objetivos, contenidos, metodología y apuntes para la reflexión de la acción formativa sobre mediación que, en esta universidad, se vienen realizando específicamente en el ámbito de las drogodependencias y adicciones.MurciaConsejería de Educación, Formación y Empleo. Servicio de Publicaciones y Estadística; Avda. de la Fama, 15 - 1ª Planta; 30006 Murcia; Tel. +34968279685; Fax +34968279835; [email protected]

Zooplankton as a Transitional Host for Escherichia coli in Freshwater

none18The contamination of freshwater with feces-derived bacteria is a major concern regarding drinking water acquisition and recreational activities. Ecological interactions promoting their persistence are still very scarcely studied. This study, which analyses the survival of E. coli in the presence of zooplankton, is thus of ecological and water safety relevance.This study shows that Escherichia coli can be temporarily enriched in zooplankton under natural conditions and that these bacteria can belong to different phylogroups and sequence types (STs), including environmental, clinical, and animal isolates. We isolated 10 E. coli strains and sequenced the genomes of two of them. Phylogenetically, the two isolates were closer to strains isolated from poultry meat than to freshwater E. coli, albeit their genomes were smaller than those of the poultry isolates. After isolation and fluorescent protein tagging of strains ED1 and ED157, we show that Daphnia sp. can take up these strains and release them alive again, thus becoming a temporary host for E. coli. In a chemostat experiment, we show that this association does not prolong bacterial long-term survival, but at low abundances it also does not significantly reduce bacterial numbers. We demonstrate that E. coli does not belong to the core microbiota of Daphnia, suffers from competition by the natural Daphnia microbiota, but can profit from its carapax to survive in water. All in all, this study suggests that the association of E. coli with Daphnia is only temporary, but the cells are viable therein, and this might allow encounters with other bacteria for genetic exchange and potential genomic adaptation to the freshwater environment. IMPORTANCE The contamination of freshwater with feces-derived bacteria is a major concern regarding drinking water acquisition and recreational activities. Ecological interactions promoting their persistence are still very scarcely studied. This study, which analyses the survival of E. coli in the presence of zooplankton, is thus of ecological and water safety relevance.noneDi Cesare, Andrea; Riva, Francesco; Colinas, Noemi; Borgomaneiro, Giulia; Borin, Sara; Cabello-Yeves, Pedro J; Canale, Claudia; Cedraro, Nicholas; Citterio, Barbara; Crotti, Elena; Mangiaterra, Gianmarco; Mapelli, Francesca; Mondino, Vincenzo; Vignaroli, Carla; Quaranta, Walter; Corno, Gianluca; Fontaneto, Diego; Eckert, Ester MDi Cesare, Andrea; Riva, Francesco; Colinas, Noemi; Borgomaneiro, Giulia; Borin, Sara; Cabello-Yeves, Pedro J; Canale, Claudia; Cedraro, Nicholas; Citterio, Barbara; Crotti, Elena; Mangiaterra, Gianmarco; Mapelli, Francesca; Mondino, Vincenzo; Vignaroli, Carla; Quaranta, Walter; Corno, Gianluca; Fontaneto, Diego; Eckert, Ester