Abstract: The essential oil from the rhizomes of Aframomum sceptrum (Zingiberaceae) was analyzed by GC/MS, and its major constituents were found to be β-pinene (12.7%), caryophyllene oxide (10.0%), and cyperene (6.0%). The oil was also evaluated for antimicrobial activities, in comparison with β-pinene, caryophyllene oxide, and the leaf essential oil of Melaleuca alternifolia (Myrtaceae). The A. sceptrum essential oil exhibited bacteriostatic activity against the Gram-positive bacteria Bacillus subtilis, Staphylococcus epidermidis, and S. aureus, but not against Gram-negative bacteria. Moreover, it showed mild fungicidal activity against Candida albicans and Aspergillus fumigates, and remarkable antiprotozoal activity against Trypanosoma brucei brucei (MLC of 1.51 μl/ml) and Trichomonas vaginalis (IC(50) of 0.12±0.02 and MLC of 1.72 μl/ml).
Abstract: Polyurethane catheters made of Pellethane 2363-80AE® were treated with a low temperature plasma developed for the decontamination of reusable polymer devices in hospitals. We investigated the modifications of the polymer surface by studying the topographic modifications, the chemical modifications, and their consequences on the wettability and bacterial adhesion. This study showed that plasma treatment modified the topography and grafted oxygen and nitrogen species onto the surface, resulting in an increase in the surface polarity. This effect could be correlated to the number of nitrogen atoms interacting with the surface. Moreover, this study demonstrated the significance of multiscale heterogeneities, and the complexity of industrial medical devices made from polymers. Their surface can be heterogeneous, and they contain additives that can migrate and change the surface composition.
Abstract: Recent outbreaks of Clostridium difficile infection have been related to the emergence of the NAP1/027 epidemic strain. This strain demonstrates increased virulence and resistance to the C-8-methoxyfluoroquinolones gatifloxacin and moxifloxacin. These antibiotics have been implicated as major C. difficile infection-inducing agents. We investigated by real-time reverse transcription-PCR the impact of subinhibitory concentrations of ampicillin, clindamycin, ofloxacin, and moxifloxacin on the expression of genes encoding three colonization factors, the protease Cwp84, the high-molecular-weight S-layer protein, and the fibronectin-binding protein Fbp68. We have previously shown in six non-NAP1/027 moxifloxacin-susceptible strains that the presence of ampicillin or clindamycin induced an upregulation of these genes, whereas the presence of fluoroquinolones did not. The objective of this study was to analyze the expression of these genes under the same conditions in four NAP1/027 strains, one moxifloxacin susceptible and three moxifloxacin resistant. Two in vitro-selected moxifloxacin-resistant mutants were also analyzed. Moxifloxacin resistance was associated with the Thr82-->Ile substitution in GyrA in all but one of the moxifloxacin-resistant strains. The expression of cwp84 and slpA was strongly increased after culture with ampicillin or clindamycin in NAP1/027 strains. Interestingly, after culture with fluoroquinolones, the expression of cwp84 and slpA was only increased in four moxifloxacin-resistant strains, including the NAP1/027 strains and one of the in vitro-selected mutants. The overexpression of cwp84 was correlated with increased production of the protease Cwp84. The historical NAP1/027 moxifloxacin-susceptible strain and its mutant appear to be differently regulated by fluoroquinolones. Overall, fluoroquinolones appear to favor the expression of some colonization factor-encoding genes in resistant C. difficile strains. The fluoroquinolone resistance of the NAP1/027 epidemic strains could be considered an ecological advantage. This could also increase their colonization fitness and promote the infection.
Abstract: Physicochemical simulation (pH, electrolytes and temperature) of three physiological media was carried out in order to follow the release of trace elements contained in seven edible clays (mainly kaolinite, illite, muscovite and quartz) collected from the West African countries of Cote d'Ivoire, Guinee and Senegal. These clays are ingested by pregnant women for diverse reasons that are related to their condition. Simulated oral (6.5<pH<7), stomach (pH approximately 1.8) and intestinal (pH approximately 8.3) media were prepared separately in order to compare the quantities of the trace elements released. Samples were analyzed by inductively coupled plasma emission spectrometry and spectrophotometry for the evaluation of copper, iron ((Fe(II) and Fe(III)), lead, manganese, nickel and zinc, since some of these elements can palliate deficiency problems and others can induce toxic effects. The quantities of the chemical elements released were pH dependent. The lower the pH, the higher the quantities of copper, Fe(III) and zinc. The quantities of Fe(II) were similar at both lower (stomach) and higher (intestinal) pH values. However, the quantities of manganese, nickel and lead were lower than quantification limits. Heating (110 degrees C) of the clays increased the quantities of trace elements released and could also participate in the microbiological 'decontamination' of raw materials. Microbiological analysis shows that all samples tested were in compliance with the recommendations of the European Pharmacopoeia. To verify the existence of possible beneficial and hazardous effects on human health, the quantities of copper, iron and zinc were compared with the recommended allowances for trace elements in France. In addition, the quantities of manganese, nickel and lead were compared with the maximum admissible concentrations in drinking water.
Abstract: A w/o/w multiple emulsion drug carrier system has been developed for local vaginal therapy. To improve its efficacy and to extend the antimicrobial spectrum activity of benzalkonium chloride (CBZ), which is introduced in the external aqueous phase, chlorhexidine digluconate (CHD) was added to the internal aqueous phase of the multiple emulsions. The minimal bactericidal concentrations (MBC) for the association of CHD and CBZ in emulsion were determined towards Escherichia coli and Staphylococcus aureus. The main release mechanism considered for the CHD encapsulated in the inner phase was a swelling-breakdown phenomenon which followed dilution of the emulsion under hypo-osmotic conditions. In order to demonstrate this release, the bactericidal effect of multiple emulsions undiluted and diluted 1-5 and 1-10 in hypo-osmotic conditions at two CHD concentrations was evaluated. To validate and quantify this release, rheological and release kinetics studies were used. The bactericidal activity of combination CBZ-CHD in the emulsion was synergistic on the two bacterial strains and the release of encapsulated CHD in the internal phase was obtained following its dilution in hypo-osmotic conditions. Vaginal administration could be carried out following dilution at 1-5 in sterile water for multiple emulsions containing the lower concentration of CHD.
Abstract: Twenty plants, belonging to sixteen families, used in traditional New Caledonian and Vanuatu medicine for treatment of symptoms potentially related to tuberculosis (cough, fever or inflammation) were screened for antimycobacterial activity. We also screened an original endemic plant, Amborella trichopoda, only member of the monogeneric family Amborellaceae and considered the most primitive living angiosperm. In total, 55 extracts were evaluated for inhibitory activity against Mycobacterium bovis BCG strain at a concentration of 100 microg/ml. Methanolic and dichloromethane extracts of Amborella trichopoda, Codiaeum peltatum, Myristica fatua, and essential oils Myoporum crassifolium showed an activity at this concentration. Methanolic extract of Amborella trichopoda fruits presented a significant activity with a minimal inhibitory concentration included between 1 and 2.5 microg/ml. In the same conditions, this activity was comparable with those of the reference drugs pyrazynamide and ethambutol, at 20 and 2.5 microg/ml, respectively.
Abstract: Antibiotic resistance in C. difficile by efflux has been previously suggested. The genome of C. difficile 630 was screened for sequences encoding putative proteins homologous to NorA from Staphylococcus aureus. Four ORFs homologous to efflux genes were cloned into the pAT79 shuttle vector under the control of transcription and translation signals of Gram-positive bacteria and expressed in Enterococcus faecalis JH2-2 and S. aureus RN4220. One of these sequences, designated cme conferred resistance to ethidium bromide, safranin O, and erythromycin in E. faecalis. The three other ORFs did not confer detectable resistance in both bacteria.
Abstract: The microbicidal activity of a W/O/W multiple emulsion destined for vaginal application, containing lactic acid in the internal aqueous phase, octadecylamine (ODA) in the oily phase and benzalkonium chloride (CBZ) in the external aqueous phase was evaluated against three microbial strains: Escherichia coli, Staphylococcus aureus and Candida albicans. The results were different depending on the procedure used. Interpretable results were obtained if only a gentle agitation was used just after the introduction of the microbial suspension to the product. This suggested that vigorous agitation lead to a variable fraction of CBZ or ODA entrapped in the micelles of ethylene and propylene oxide copolymer (COE).
Abstract: The synthesis of diaqua(1,10-phenanthroline-N,N')(thiosulfato-O,S)manganese(ll) [Mn(phen)(S(2)O(3))(H(2)O)(2)] was investigated. Its structure was determined by single crystal X-ray diffraction from 2418 reflections (I > 3 sigma(I)) to a final value of R = 0.047 and Rw = 0.054. Crystal data are as follows : space group P(2) (1); a = 10.356(3), b = 7.097(3), c = 20.316(2) A, beta = 94.29(2) degrees , V = 1489.1(8) , A(3), Z = 2. There are two independent title compounds in the asymetric unit. Each manganese atom has a distorted octahedral Mn(SO)N(2)O(2) geometry with the S and O atoms (from two neighbouring thiosulfate ligands) mutually trans, two N atoms from the 1,10-phenanthroline ligand and two water oxygen. The thiosulfate group behaves as a bridging ligand, connecting, through sulfur and oxygen, Mn atoms related by the binary b translation, thus forming infinite chains running parallel to this axis. Infrared and electronic spectra are reported.
Abstract: Hydrophilic and electrostatic cell surface properties of eight Lactobacillus strains were characterized by using the microbial adhesion to solvents method and microelectrophoresis, respectively. All strains appeared relatively hydrophilic. The strong microbial adhesion to chloroform, an acidic solvent, in comparison with microbial adhesion to hexadecane, an apolar n-alkane, demonstrated the particularity of lactobacilli to have an important electron donor and basic character and consequently their potential ability to generate Lewis acid-base interactions with a support. Regardless of their electrophoretic mobility (EM), strains were in general slightly negatively charged at alkaline pH. A pH-dependent behavior concerning cell surface charges was observed. The EM decreased progressively with more acidic pHs for the L. casei subsp. casei and L. paracasei subsp. paracasei strains until the isoelectric point (IEP), i.e., the pH value for which the EM is zero. On the other hand, the EM for the L. rhamnosus strains was stable from pH 8 to pH 3 to 4, at which point there was a shift near the IEP. Both L. casei subsp. casei and L. paracasei subsp. paracasei strains were characterized by an IEP of around 4, whereas L. rhamnosus strains possessed a markedly lower IEP of 2. The present study showed that the cell surface physicochemical properties of lactobacilli seem to be, at least in part and under certain experimental conditions, particular to the bacterial species. Such differences detected between species are likely to be accompanied by some particular changes in cell wall chemical composition.
Abstract: The bactericidal activity of various disinfectants (cationic or amphoteric surfactants, oxidizing agents, phenolic derivatives) was determined against Escherichia coli CIP 54127 obtained by culture on tryptic soy agar (in-suspension or on-germ-carrier test) or in the form of biofilms produced in a continuous culture system. The bacteria tested on germ-carriers or included in biofilms were more resistant than the same strain in suspension. The extent of the reduction in activity depended on the nature of the disinfectant. In the two cases, the greatest reduction was observed with benzalkonium chloride and hexadecyl trimethylammonium bromide, the agents with the lowest hydrophile-lipophile balance. The activity of the oxidizing agents (sodium hypochlorite, peracetic acid/H2O2) and alkyl trimethylammonium derivatives (C12 and C14) was somewhat reduced, while that of the phenolic derivatives (o-cresol, phenol) was either slightly attenuated or unaffected. The reduction in sensitivity was attributed to a reduced accessibility of the bacterial cells to the disinfectants, due to the fact that the former adhered to a support. Furthermore, the interfering action of the substances in contact with the bacteria (milk in the germ-carrier test and exopolymers in the biofilms) could play a role. The reduced sensitivity of the bacteria in the biofilms was not due to any alteration in the metabolic state of the bacteria (mostly in a quiescent state) since this resistance was lost after the mechanical resuspension of the cells before the contact with the disinfectants.
Abstract: The attachment of Salmonella choleraesuis subsp. choleraesuis ATCC 15790 to beef muscle and adipose tissues was investigated. S. choleraesuis was found to adhere in higher numbers to muscle than to fat. The charge and the hydrophobicity of the surface of S. choleraesuis were evaluated by measurement of electrophoretic mobility, the contact angle with water, adhesion to hexadecane, and hydrophobic interaction chromatography. The overall negative charge of S. choleraesuis was masked by the high electrolyte concentration in the attachment medium (0.15 M phosphate-buffered saline). This bacterium was shown to possess a hydrophilic surface. Electrostatic interactions do not affect the attachment of S. choleraesuis to both lean and fat tissue, and there was no evidence for a role of hydrophobic interactions. However, the attachment of S. choleraesuis was reduced by 90% after mechanical removal of the flagella or after treatment of the bacteria with specific antiflagella serum. This reduction was attributed to a loss of bacterial mobility leading to a reduction in the number of cells reaching the tissue during the period of contact. Treatment of the tissue with a concentrated suspension of flagella or treatment of the bacteria with antisomatic serum (OMD) did not reduce the attachment of S. choleraesuis to tissues, indicating an absence of specific attachment sites for flagella or antigen O on the beef tissue surface.
