Aeromonas, un microorganismo ambiental de importancia en salud humana y animal

L'objectiu general va ser determinar la prevalença de Aeromonas spp en les 1365 soques identificades, 543 provenien d’aigua, 416 de mostres clíniques humanes i 203 procedents de peixos (carpes i truites), hortalisses i mariscs. S’investiga la seva presencia en agua regenerada procedent d’un tractament terciari per llacunatge i per llum UV i clor (UV + Cl). aquesta ultima utilitzades per el re d’hortalisses. El llacunatge només va reduir en un 82% la concentració de Aeromonas que s’eliminaren totalment després del tractament UV + Cl. No obstant això, es va observar recreixement en aquesta l'aigua emmagatzemada utilitzada per al reg. La mateixa soca de A. caviae s’aillá en l'aigua de rec i en l'enciam regat amb aquesta aigua, i el mateix va passa amb una soca de A. saranelli trobada en el julivert i en els tomàquet. Es fa pales per tant que l'aigua regenerada utilitzada per al rec es la fon de dispersió d’ especies patògenes de Aeromonas. L'espècie A. schubertii va ser recuperada per primer cop de musclos i l'espècie A. dhakensis del d'un dofí mort per una pneumònia. La identificació dels aïllats clínics en el MALDI-TOF va mostrar menys d'un 10% d'identificacions errònies. Això es degut a que la base de dades esta poc actualitzada e inclou, a més, soques erròniament etiquetades. Les soques clíniques corresponien a 9 espècies A. caviae (61,6%), A. veronii (21,6%), A. hydrophila (6,4%), A. media (4,5%) i A. dhakensis (1,2%), seguides de A. allosaccharophila, A. salmonicida i A. bestiarum (amb una incidència de 0,5% o inferior) i a 2 noves espècies recuperades de femta humana. A més, es van descobrir 5 noves espècies, 4 a partir d'aigua de llac i una a partir de mol•luscs bivalves.El objetivo general fue determinar la prevalencia de Aeromonas spp, a partir de 1365 cepas, 543 procedentes de agua, 416 de muestras clínicas humanas y 203 de peces (carpas y truchas), hortalizas y mariscos. Se investigo su presencia en agua regenerada (tratamiento terciario) procedente de lagunaje y de un tratamiento de luz UV y cloro (UV + Cl), esta ultima utilizada para el riego de hortalizas. El sistema de lagunaje sólo redujo la concentración de Aeromonas en un 82% pero se eliminaron totalmente con UV + Cl. Sin embargo, esta última agua presento de nuevo estas bacterias al ser almacenada para el riego. La misma cepa de A. caviae (con igual genotipo) se aíslo en el agua utilizada para el riego y en la lechuga regada con dicha agua, como ocurrió con una cepa de A. saranelli encontrada en el perejil y los tomates. Se demostró por tanto que el agua regenerada utilizada para el riego es la fuente de dispersión de especies patogenas de Aeromonas. La especie A. schubertii fue recuperada por primera vez de mejillones y la especie A. dhakensis de un delfín muerto por una neumonía. La identificación de los aislados clínicos mediante MALDI-TOF generó un 10% de identificaciones erróneas. Esto es debido a que la base de datos esta poco actualizada e incluye, además, especies erróneas. Las cepas clínicas pertenecieron a 9 especies conocidas: A. caviae (61,6%), A. veronii (21,6%), A. hydrophila (6,4%), A. media (4,5%) y A. dhakensis (1,2%), seguidas de A. allosaccharophila, A. salmonicida y A. bestiarum (con una incidencia de 0,5% o inferior) y a 2 nuevas especies recuperadas de heces humanas. Además, se descubrieron 5 nuevas especies más 3 procedentes de agua de lago y otra a partir de moluscos bivalvos.The general objective of this PhD Thesis was to determine the prevalence of Aeromonas spp. found by sequencing the rpoD gene among the 1365 identified strains. Two types of tertiary treated reclaimed water, one after a lagooning and the other after UV and chlorine (UV+ Cl) treatment were, together with other environmental waters, the dominating origin of the isolates (n=543), followed by 416 strains from human clinical samples and 203 that came from fish (carp and trout’s), vegetable irrigated with the reclaimed water and shellfish. The most relevant findings were that the lagooning system only reduced in an 82% the concentration of Aeromonas vs the 100% elimination after UV+Cl. However, re-growth was observed in the stored water use for irrigation. The same strain (ERIC genotrype) of A. caviae was found in the water used for irrigation and in the irrigated lettuce, as occurred for a strain of A. saranelli found in the parsley and in the tomatoes, indicating the origin for the strains in the reclaimed irrigation water. The species A. schubertii was recovered from the first time from mussels and the species A. dhakensis in the longs of a dolphin with a fatal pneumonia. MALDI-TOF showed less that 10% of erroneous identifications of the clinical isolates, that are generated by the poorly updated database that includes in addition erroneous species. The clinical strains corresponded to 9 know species i.e. A. caviae (61.6%), A. veronii (21.6%), A. hydrophila (6.4%), A. media (4.5%) and A. dhakensis (1.2%) followed by A. allosaccharophila, A. salmonicida and A. bestiarum (with an incidence of 0.5% or lower) and to 2 new species recovered from human faeces. In addition, 4 new species were discovered from water bodies associated to cyanobacteria blooms and a new species from bivalve molluscs

A culture independent method for the detection of Aeromonas sp. from water samples

The genus Aeromonas is present in a wide variety of water environments and is recognised as potentially pathogenic to humans and animals. Members of this genus are often confused with Vibrio when using automated, commercial identification systems that are culture-dependent. This study describes a polymerase chain reaction (PCR) detection method for Aeromonas that is culture- independent and that targets the glycerophospholopid-cholesterol acyltransferase (gcat) gene, which is specific for this genus. The GCAT-PCR was 100% specific in artificially inoculated water samples, with a detection limit that ranged from 2.5 to 25 cfu/mL. The success at detecting this pathogen in 86 water samples using the GCAT-PCR method was identical to the conventional culturing method when a pre-enrichment step was carried out, yielding 83.7% positive samples. On the other hand, without a pre-enrichment step, only 77.9% of the samples were positive by culturing and only 15.1% with the GCATPCR. However, 83.7% positive samples were obtained for the GCAT-PCR when the water volume for the DNA extraction was increased from 400 μL to 4 mL. The proposed molecular method is much faster (5 or 29 h) than the culturing method (24 or 48 h) whether performed directly or after a pre-enrichment step and it will enable the fast detection of Aeromonas in water samples helping to prevent a possible transmission to humans

Molecular characterization of Shewanella and Aeromonas isolates associated with spoilage of Common carp (Cyprinus carpio)

Storage in ice is a common way of preserving commercial fish species but some microorganisms can still contaminate and participate in the spoilage of the product; therefore, identification of potential harmful microbes is important. Thirteen colonies were isolated from common carp (Cyprinus carpio) that had been stored in ice, whose phenotypic identification revealed that they belonged to the genera Aeromonas (n = 5) and Shewanella (n = 8). Molecular genotyping with ERIC-PCR showed clonality only among two of the five Aeromonas isolates and for two groups (n = 3; n = 2) of the eight Shewanella isolates. Sequencing the rpoD gene showed that four Aeromonas isolates belonged to the species Aeromonas salmonicida and one to A. sobria. Of the eight Shewanella, seven isolates cluster with Shewanella putrefaciens and one with Shewanella profunda in the 16S rRNA phylogenetic tree. However, analysis of the gyrB gene showed that these eight isolates could constitute a new species closely related to S. baltica. The Shewanella and A. salmonicida isolates produce off-odours and reduce trimethylamine oxide, indicating that they might contribute to the spoilage of the fish.Fil: Beaz Hidalgo, Roxana. Universitat Rovira I Virgili; EspañaFil: Agüeria, Daniela Alejandra. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto Multidisciplinario de Ecosistemas y Desarrollo Sustentable; ArgentinaFil: Latif Eugenín, Fadua. Universitat Rovira I Virgili; EspañaFil: Yeannes, Maria Isabel. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Figueras, Maria J.. Universitat Rovira I Virgili; Españ

Aislamiento de Plesiomonas shigelloides y Aeromonas veronii biotipo sobria en heces de lobo marino común sudamericano, Otaria flavescens (Shaw, 1800)

Plesiomonas shigelloides and Aeromonas spp. are Gram negative bacteria vastly distributed in the environment, being isolated from aquatic ecosystems and terrestrial and marine animals. The South American sea lion (Otaria flavescens) is the most frequent marine mammal of the Chilean coasts, living in beaches, rocks or coastline of rivers. In this work we determined the isolation frequency of P. shigelloides and A. veronii biotype sobria in fecal samples of South American sea lions belonging to a colony established at the urban South coastline of Valdivia River, southern Chile. From the 30 samples under study, P. shigelloides was isolated in 27 (90.0%) and A. veronii biotype sobria in 17 (56.6%). To our knowledge, this is the first report of the isolation of P. shigelloides and Aeromonas spp. from South American sea lions in Chile. However, further studies are needed to clarify if these bacteria play any role in producing disease, or are merely commensals, in these marine mammals

Especies de la familia Enterobacteriaceae en heces de lobo marino común, Otaria flavescens establecido en el río Valdivia

This study aims to establish the isolation frequency of species of the family Enterobacteriaceae in fecal samples of South American common sea lion (Otaria flavescens). Thirty fecal samples were collected from the resting ground of an urban sea lions colony in Valdivia, southern Chile. The bacteria species and their isolation frequencies were Edwarsiella tarda (73%), Escherichia coli (70%), Hafnia alvei (33%), Morganella morganii (7%), Proteus mirabilis (7%), Klebsiella pnuemoniae subsp. pneumoniae (3%), Serratia rubidea (3%), Providencia rustigianii (3%) and Citrobacter braakii (3%)

Adhesive and invasive capacities of Edwarsiella tarda isolated from South American sea lion

Edwarsiella tarda is a zoonotic bacterium that can be isolated from humans, animals and the environment. Although E. tarda is primarily considered a fish pathogen, it is the only species of its genus considered to be pathogenic for humans as well. A survey of zoonotic intestinal bacteria in fresh feces from South American sea lions (SASL) Otaria flavescens, reported E. tarda as the most frequently isolated species. In this study, we used HEp-2 cells to establish in vitro the adherence and invasive ability of 17 E. tarda strains isolated from SASL fecal material. All the strains were able to adhere and invade HEp-2 cells with adhesion and invasion percentages ranging from 56 to 100% and 21 to 74%, respectively. Despite the expression of these pathogenic factors, further investigation is needed to determine whether this bacterium could play a role as primary pathogen for this and other species of pinnipeds