No abstract

A peptide antibiotic, gramicidin A, was covalently bound to cystamine self-assembled monolayers on gold surfaces. Each step of the surface functionalization was characterized by polarization modulation infrared reflection absorption spectroscopy and X-ray photoelectron spectroscopy. The antimicrobial activity of the anchored gramicidin was tested against three Gram-positive bacteria (Listeria ivanovii, Enterococcus faecalis, and Staphylococcus aureus), the Gram-negative bacterium Escherichia coli and the yeast Candida albicans. The results revealed that the adsorbed gramicidin reduced, from 60% for E. coli to 90% for C. albicans, the number of culturable microorganisms attached to the surface. The activity was proven to be persistent overtime, up to 6 months after the first use. The bacteria attached to the functionalized surfaces were permeabilized as shown by confocal microscopy. Taken together, these results indicate a bacteriostatic mode of action of the immobilized peptide. Finally, using green fluorescent protein-expressing bacteria, it was shown that the development of a bacterial biofilm was delayed on peptide-grafted surfaces for at least 24 h.

No abstract

<p>The purpose of this study was to assess <em>in vitro</em> the activity of four essential oils (<em>Cymbopogon citratus, Eucalyptus citriodora, Lippia multiflora, Melaleuca quinquenervia</em>) and the biobactericide Neco® on Gram-positive bacteria.</p><p><strong>T</strong>he aromatogram and antibiogram were assessed by the agar well diffusion method and the Muller Hinton disk-agar diffusion method, respectively. Also, the minimum inhibitory concentration and the minimum bactericidal concentration were determined by the microdilution method in liquid medium.</p><p>The aromatogram showed that the biobactericide Neco® induced the largest inhibition diameters (34.53 ± 11.82 - 43.92 ± 5.38 mm) of all strains combined, followed by the essential oils of <em>Eucalyptus Citriodora</em> (30.01 ± 3.02 - 41.89 ± 1.77 mm) and <em>Lippia multiflora</em> (20.72 ± 4.72 - 37.61 ± 2.80 mm). However, the essential oils of <em>Melaleuca quinquenervia</em> (19.99 ± 3.93 - 26.20 ± 13.27 mm) and <em>Cymbopogon citratus</em> (13.52 ± 3.59 - 29.08 ± 2.35 mm) had the smallest inhibition diameters. Moreover, the comparison of the activities of the aromatogram and antibiogram revealed generally that activities were higher with essential oils than with antibiotics.</p><p>At the end of this study, the essential oils of <em>Cymbopogon citratus</em>, <em>Eucalyptus citriodora, Lippia multiflora, Melaleuca quinquenervia</em> and the biobactericide Neco® had an antibacterial activity on Gram+ bacteria.</p><p><strong><br /></strong></p>

Background: The increasing phenomenon of bacterial resistance to antibiotics is a real public health problem. The main causes are poor management of hygiene and water quality, but also the use of antibiotics without precaution. The objective of this study was to isolate and determine the antibiotic resistance profile of the different bacteria found in the main hospitals and bacteriology laboratories in Gabon. Methods: 6034 samples were taken from hospitals in seven main cities of Gabon, and analyzed according to the usual techniques. The pathogenic strains were identified by Matrix-Assisted Laser Desorption Ionization-Time Of Flight Mass Spectrometry. Antimicrobial susceptibility testing was performed by the agar disc diffusion method, according to the Antibiogram Committee of the French Society for Microbiology guidelines. Results: 974 pathogenic bacterial strains were found, including 890/974 (91.4%) Gram-negative bacilli. The systematic antimicrobial susceptibility testings identified 160/974 (16.4%) multi-resistant strains. Escherichia coli was the most represented species. 12.

This study aims at assessing the in vitro activity of Cymbopogon citratus, Eucalyptus citriodora, Lippia multiflora, Melaleuca quinquenervia essential oils and the biobactericide Neco® on extended-spectrum β-lactamases producing or non-producing bacterial strains (ESBL) isolated at the Armed forces hospital of Libreville. The aromatogram and antibiogram were respectively assessed by the agar well diffusion method and agar disc method. Thus, the minimum inhibitory concentration and minimum bactericidal concentration were determined by the microdilution method in liquid medium. The aromatogram revealed that the biobactericide Neco® induced the largest inhibition diameters (28.42 -43.27 mm) in all strains, followed by E. citriodora (26.96 -36.12 mm) and L. multiflora (15.32 -41.42 mm) essential oils. In contrast, M. quinquenervia (9.83 -26.64 mm) and C. citratus (6.82 -14.97 mm) essential oils had the smallest inhibition diameters. Furthermore, the comparison of aromatogram and antibiogram activities generally revealed that activities are better with essential oils than with antibiotics. In addition, no significant differences were observed between ESBL producing or nonproducing strains. At the end this study, the antibacterial activity of C. citratus, E. citriodora, L. multiflora, M. quinquenervia essential oils and the biobactericide Neco® were highlighted. However, the efficiency of these activities is dependent on the intrinsic composition of the plant.

Étude phénotypique de la résistance des bactéries isolées des eaux des lacs et rivières de la ville de Franceville aux céphalosporines de troisième génération ABSTRACT Objective :This study investigates the susceptibility of Gram-bacteria (Aeromonas salmonicida, Escherichia coli 1, Escherichia coli 2, Klebsiella pneumoniae rhinosclero, Pseudomonas aeruginosa and Yersinia enterocolitica) to third generation cephalosporins (ceftriaxone, cefotaxime, cefpodoxime and cefixime) using water samples collected from the lakes, the M'passa and the Ogooué Rivers in Gbon. Methodology and Results: The bacteria were first re-identified by the Api 20 E system, and then subjected to the antibiogram to evaluate of their sensibilities to four (4) antibiotics, namely ceftriaxone, cefotaxime, cefpodoxime and cefixime. Therefore, the susceptibility of bacteria to the third generation cephalosporins was evaluated by the well method in Mueller Hinton agar. The diameter of the inhibition zone around each well was obtained after 18-24 hours of incubation and measured by means of a caliper. The results of this study revealed that the tested bacterial strains fall into two major groups, the sensible and the multiresistance ones. Indeed, Escherichia coli 1, Escherichia coli 2, Klebsiella pneumoniae rhinosclero, Yersinia enterocolitica were susceptible to ceftriaxone and cefotaxime. While, the multiresistance was observed with Pseudomonas aeruginosa, Aeromonas salmonicida and Escherichia coli of the hospital who presents quite a character of resistant to four (4) antibiotics. Conclusion and application of results: In summary, the phenomenon of multiresistance was observed in the bacteria isolated from the waters samples of Franceville. Therefore, it is important to set up a system for monitoring and monitoring the microbiological quality of these waters.