Aeromonas lusitana sp. nov., Isolated from Untreated Water and Vegetables.

During previous studies to evaluate the phylogenetic diversity of Aeromonas from untreated waters and vegetables intended for human consumption, a group of isolates formed a unique gyrB phylogenetic cluster, separated from those of all other species described so far. A subsequent extensive phenotypic characterization, DNA-DNA hybridization, 16S rRNA gene sequencing, multi-locus phylogenetic analysis of the concatenated sequence of seven housekeeping genes (gyrB, rpoD, recA, dnaJ, gyrA, dnaX, and atpD; 4705 bp), and ERIC-PCR, were performed in an attempt to ascertain the taxonomy position of these isolates. This polyphasic approach confirmed that they belonged to a novel species of the genus Aeromonas, for which the name Aeromonas lusitana sp. nov. is proposed, with strain A.11/6(T) (=DSMZ 24095(T), =CECT 7828(T)) as the type strain.

Antibacterial activity and synergistic effect between watercress extracts, 2-phenylethyl isothiocyanate and antibiotics against 11 isolates of Escherichia coli from clinical and animal source.

UNLABELLED: To evaluate the possible in vitro interaction between natural extracts of watercress (Nasturtium officinale R. Br.) and 2-phenylethyl isothiocyanate, a natural compound derived gluconasturtiin largely present in watercress tissues, with a standard antibiotic, a synergy study was carried out against 11 isolates of extended-spectrum ß-lactamases-Escherichia coli. Aqueous and methanolic watercress extracts and 2-phenylethyl isothiocyanate were combined with the antibiotic, and a disc diffusion assay and minimum inhibitory concentration methods were used to assess the in vitro antibacterial activity. The results of this study showed that there is an increase in antibacterial activity of the antibiotic when it was combined with plants extracts and pure compounds. The most interesting result was the combination between 2-phenylethyl isothiocyanate and the antibiotic. Synergistic effects of the antibiotic with watercress extracts and 2-phenylethyl isothiocyanate suggest the potential of these plants and their natural compounds to improve the performance of the antibiotics and could be an interesting tool for antimicrobial therapy. The results led us to conclude that watercress has important pharmacological substances which can be used for developing new and effective antimicrobial agents. SIGNIFICANCE AND IMPACT OF THE STUDY: This in vitro study intends to demonstrate the potential use of watercress extracts and 2-phenylethyl isothiocyanate as antimicrobial tools against extended-spectrum ß-lactamases-Escherichia coli and to determine their ability to act synergistically with commercial standard antibiotics. We intended to increase the knowledge about different clinical and pharmaceutical approaches to fight against E. coli rather than the traditional use of antibiotics. The results may be useful to those involved in the pharmaceutical, biochemical and microbiology industry and/or academic research in terms of developing alternative control measures and efficient intervention methods.

Multilocus phylogenetic analysis of the genus Aeromonas.

A broad multilocus phylogenetic analysis (MLPA) of the representative diversity of a genus offers the opportunity to incorporate concatenated inter-species phylogenies into bacterial systematics. Recent analyses based on single housekeeping genes have provided coherent phylogenies of Aeromonas. However, to date, a multi-gene phylogenetic analysis has never been tackled. In the present study, the intra- and inter-species phylogenetic relationships of 115 strains representing all Aeromonas species described to date were investigated by MLPA. The study included the independent analysis of seven single gene fragments (gyrB, rpoD, recA, dnaJ, gyrA, dnaX, and atpD), and the tree resulting from the concatenated 4705 bp sequence. The phylogenies obtained were consistent with each other, and clustering agreed with the Aeromonas taxonomy recognized to date. The highest clustering robustness was found for the concatenated tree (i.e. all Aeromonas species split into 100% bootstrap clusters). Both possible chronometric distortions and poor resolution encountered when using single-gene analysis were buffered in the concatenated MLPA tree. However, reliable phylogenetic species delineation required an MLPA including several "bona fide" strains representing all described species.

Clinical relevance of the recently described species Aeromonas aquariorum.

Twenty-two human extraintestinal isolates (11 from blood) and three isolates recovered from patients with diarrhea were genetically characterized as Aeromonas aquariorum, a novel species known only from ornamental fish. The isolates proved to bear a considerable number of virulence genes, and all were resistant to amoxicillin (amoxicilline), cephalothin (cefalotin), and cefoxitin. Biochemical differentiation from the most relevant clinical species is provided.