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

The improved PCR of the fstA (ferric siderophore receptor) gene differentiates the fish pathogen Aeromonas salmonicida from other Aeromonas species

10.1016/j.vetmic.2013.06.02

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

‘Aeromonas intestinalis’ and ‘Aeromonas enterica’ isolated from human faeces, ‘Aeromonas crassostreae’ from oyster and ‘Aeromonas aquatilis’ isolated from lake water represent novel species

Abstract Four Aeromonas strains from clinical and environmental samples differed from known species on the basis of rpoD gene sequence. Multilocus phylogenetic analysis and in silico DNA-DNA hybridization confirmed them as four new species even though their 16S rRNA gene sequence similarity with their closest relatives was >98.7%, as occurred for other Aeromonas spp.Peer reviewe

Aeromonas aquatica sp. nov., Aeromonas finlandiensis sp. nov. and Aeromonas lacus sp. nov. isolated from Finnish waters associated with cyanobacterial blooms

Three groups of Aeromonas strains isolated from Finland lakes experiencing cyanobacterial blooms could not be assigned to any known species of this genus on the basis of 16S rRNA and rpoD gene sequences. The Multilocus Phylogenetic Analysis (MLPA) of the concatenated sequence of seven genes (gyrB, rpoD, recA, dnaJ, gyrA, dnaX and atpD; 4093bp) showed that the three groups of strains did not cluster with any known Aeromonas spp. and formed three independent lineages. This was confirmed by performing the analysis with their closest relatives using 15 genes (the latter 7 and cpn60, dnaK, gltA, mdh, radA, rpoB, tsf, zipA; 8751bp). Furthermore, ANI results between the genomes of the type strains of the three potential new species and those of their close relatives were all <96% which is the previously proposed cutoff value for differentiating species within this genus. The in silico DDH values of the three type strains of the new species also showed a similarity <70% with the most closely related species indicating they belong to different taxa. The three groups of strains could be differentiated from each other and from other known Aeromonas species on the basis of several phenotypic characters. This polyphasic study revealed that the 3 groups of strains represent 3 novel Aeromonas species for which the names Aeromonas aquatica sp. nov. (type strain AE235T=CECT 8025T=LMG 26712T), Aeromonas finlandiensis sp. nov. (type strain 4287DT=CECT 8028T=LMG 26709T) and Aeromonas lacus sp. nov. (type strain AE122T=CECT 8024T=LMG 26710T) are proposed. © 2015 Elsevier GmbH

Genome-driven evaluation and redesign of PCR tools for improving the detection of virulence-associated genes in aeromonads.

Many virulence factors have been described for opportunistic pathogens within the genus Aeromonas. Polymerase Chain Reactions (PCRs) are commonly used in population studies of aeromonads to detect virulence-associated genes in order to better understand the epidemiology and emergence of Aeromonas from the environment to host, but their performances have never been thoroughly evaluated. We aimed to determine diagnostic sensitivity and specificity of PCR assays for the detection of virulence-associated genes in a collection of Aeromonas isolates representative for the genetic diversity in the genus. Thirty-nine Aeromonas strains belonging to 27 recognized species were screened by published PCR assays for virulence-associated genes (act, aerA, aexT, alt, ascFG, ascV, ast, lafA, lip, ser, stx1, stx2A). In parallel, homologues of the 12 putative virulence genes were searched from the genomes of the 39 strains. Of the 12 published PCR assays for virulence factors, the comparison of PCR results and genome analysis estimated diagnostic sensitivities ranging from 34% to 100% and diagnostic specificities ranged from 71% to 100% depending upon the gene. To improve the detection of virulence-associated genes in aeromonads, we have designed new primer pairs for aerA/act, ser, lafA, ascFG and ascV, which showed excellent diagnostic sensitivity and specificity. Altogether, the analysis of high quality genomic data, which are more and more easy to obtain, provides significant improvements in the genetic detection of virulence factors in bacterial strains

Re-identification of Aeromonas isolates from rainbow trout and incidence of class 1 integron and ß-lactamase genes

10.1016/j.vetmic.2014.06.01