Synergistic Actions of Benzyl Isothiocyanate with Ethylenediaminetetraacetic Acid and Efflux Pump Inhibitor Phenylalanine-Arginine ß-Naphthylamide Against Multidrug-Resistant Escherichia coli.

The aim of this study was to assess the efficacy of benzyl isothiocyanate (BITC) in combination with efflux inhibitors and metal chelators against multidrug-resistant Escherichia coli. In vitro synergism between testing molecules was observed based on the minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC), fractional inhibitory concentration index (FICI), bactericidal kinetics, and growth inhibition assay. BITC alone exhibited moderate antibacterial activity against E. coli strains with MIC and MBC values of 0.625-1.25 µM and 1.25-2.5 µM, respectively. In contrast, double and triple combinations of BITC, ethylenediaminetetraacetic acid (EDTA), and phenylalanine-arginine ß-naphthylamide (PAßN) resulted in synergistic activities with FICI values between 0.18 and 0.5, whereas combination of BITC with carbonyl cyanide m-chlorophenyl hydrazone or 2, 2'-dipyridyl revealed additive or indifference effect with FICI values of 0.75-1.5 and 1-1.5, respectively. Results of bactericidal kinetics and growth inhibition assays also supported the synergistic effects of EDTA and PAßN with BITC against E. coli strains. Our data demonstrate the possible use of adjuvant agents, such as the chelating agent EDTA and the efflux inhibitor PAßN to improve the antibacterial potential of isothiocyanate and may help to develop an alternative strategy for reducing the occurrence of multidrug resistance.

First insights on organic cosolvent effects on FhuA wildtype and FhuA Δ1-159.

Circular dichroism (CD) and deconvolution were used to study the structural integrity of a "plugged" and an "open" FhuA transmembrane channel protein in the presence of varied concentrations of tetrahydrofuran (THF), ethanol (EtOH) and chloroform/methanol (C/M). FhuA is an Escherichia coli outer membrane protein (78.9 kDa) consisting of 22 ß-sheets and an internal globular cork domain which acts as an iron transporter. FhuA and the deletion variant FhuA Δ1-159 showed comparable and remarkable resistance in the presence of THF (≤40 vol%) and EtOH (≤10 vol%). In C/M, significant differences in structural resistance were observed (FhuA stable ≤10 vol%; FhuA Δ1-159 ≤1 vol%). Deconvolution of CD-spectra for FhuA and FhuA Δ1-159 yielded ß-sheet contents of 61 % (FhuA) and 58% (FhuA Δ1-159). Interestingly, FhuA and FhuA Δ1-159 had comparable ß-sheet contents in the presence and absence of all three organic cosolvents. Additionally, precipitated FhuA and FhuA Δ1-159 (in 40 vol% C/M or 65 vol% THF) redissolved by supplementing the detergent n-octyl-oligo-oxyethylene (oPOE).

[Influence modified and resistant potato starches on the E. coli culture].

Modified and resistant starches regulate the colon microbiota metabolism and gene expression. This adaptive response allows bacteria to obtain the new enzymes to metabolize the unusual substrates. The potato starches modify the colon residential microorganisms. It was a reason the study the influence of the modified and resistant potato starches on the E. coli lines defected in the gene reparation system. It allows us to estimate the participation of some components of gene reparation system in the adoptive response of bacteria to the chemical compounds. Potato starches in the concentration 1% have been found to be indifferent to the DNA E. coli lines Wp. RecA. PolA [Russian character: see text] UvrA. High amilose notato starch stimulates these lines growth that indicates to its prebiotic canacities.

Affinity capillary electrophoresis for the screening of novel antimicrobial targets.

The increasing number of multiantibiotic-resistant organisms, including methicillin-resistant Staphylococcus aureus (MRSA), requires the development of novel chemotherapies that are structurally distinct and exempt from current resistance mechanisms. Bioinformatics data mining of microbial genomes has revealed numerous previously unexploited essential open reading frames (ORFs) of unknown biochemical function. The potential of these proteins as screening targets is not readily apparent because most screening technologies rely on knowledge of biological function. To address this problem, the authors employed affinity capillary electrophoresis (ACE) to identify antimicrobial compounds that bound the novel target YihA. Screening a small-molecule library of 44,000 compounds initially identified 115 binders, of which 76% were confirmed. Furthermore, the ACE assay distinguished diverse compounds that possessed drug-like properties and antimicrobial activity against drug-resistant clinical isolates. These data validate ACE as a valuable tool for the fast, efficient detection of specific binding molecules that possess biological activity.