J. Dony

Prevention of the adhesion of Pseudomonas aeruginosa to human buccal epithelial cells

Abstract The influence of protamine on the adhesion of Pseudomonas aeruginosa to human buccal cells was investigated using 2 collection strains and 5 other strains isolated from the hospital environment. The serotype and pyocin type of the strains was established and their antibiotic sensitivity determined. For concentrations lower than 100 μg/ml there was a decrease in adhesion correlating with protamine concentration. Maximum inhibition was reached at about 100 μg/ml.

Analytical determination of nicotinamide using bacterial electrodes

Abstract Two bacterial electrodes have been studied for the determination of nicotinamide (vitamin PP) with a linear range of 2.8 × 10 −4 M to 2 × 10 −2 M. The used strains, although taxonomicaly different and differently improved ( E. coli mutated and B. pumilus induced), present the same nicotinamide deaminase activity, able to be used for analytical assays. Their long-term stability (more than 100-fold higher than the purified enzyme) is realized by the regeneration of living cells on the electrode itself. The parameters involved in this type of electrode construction are discussed. This type of bacterial electrodes presents a very good selectivity for nicotinamide in multivitamin pharmaceutical formulations.

An in vitro test for the evaluation of the efficacy of disinfectants

Abstract The paper presents a method for the in vitro evaluation of the effectiveness of disinfectants. It is a capacity test performed in hard water with or without horse serum. Some results are presented showing the ability of growth in disinfectant solution.

Difference of Pseudomonas aeruginosa sensitivity to chloroxylenol according to the culture medium

The authors recorded notable difference of sensitivity of Pseudomonas aeruginosa to chloroxylenol according to the growth medium; the amount of magnesium of the culture medium and the growth phase were not major factors. This difference, which can be extended to various strains, is due to a difference of permeability of the outer membrane. It is suggested that adsorption of medium components on the surface of the bacteria could participate in the phenomenon. Similar results were obtained with phenol and crystal violet.

In vitro modification of antimicrobial efficacy by protamine

Abstract The influence of serum and protamine on the in vitro effectiveness of some preservatives has been studied. The products tested were formaldehyde, benzalkonium chloride, esters of parahydroxybenzoic acid, benzoic and sorbic acids. Serum only strongly depleted the activity of benzalkonium chloride. In the case of protamine, this basic protein markedly enhanced the bactericidal effect of benzoic and sorbic acids and allowed a reduction in the concentration by a factor of four while still maintaining the same bactericidal power on Pseudomonas aeruginosa .

Influence of protamine on the susceptibility of Pseudomonas aeruginosa to cefotaxime, sulphadimethoxine, polymyxin B and some β-lactam antibiotics

Protamine, a basic protein, was shown to influence the activity of antibacterial agents. When added to tryptic soy broth it enhanced the bactericidal activity of cefotaxime, sulphadimethoxine, ticarcillin, piperacillin and carbenicillin against Pseudomonas aeruginosa. In contrast, the activity of polymyxin B against this species was markedly reduced in the presence of protamine.

Efficiency of bioconversion of steroids by Fusarium oxysporum into Δ1,4-androstadiene-3,17-dione using gas chromatography

Gas-liquid chromatography is suitable for the study of the bioconversion yield of dehydroisoandrosterone into Δ1,4-androstadiene-3, 17-dione. Fusarium oxysporum (a wild isolated strain) exhibits the greatest activity for this bioreaction. The optimalization of the bioconversion efficiency has been studied in culture media or in buffered solutions using free and immobilized cells. Microbiological (cell weight, choice of strains and substrate, induction) and physicochemical (pH, temperature, ionic strength and choice of buffers, organic solvents, artificial cofactors) factors influencing the reaction yield are discussed. The same operating conditions can be used for free and immobilized cells. For both techniques, about 90% of Δ1,4-androstadiene-3,17-dione is formed in 48 h with non-induced cells and in 24 h with induced cells. A simple prototype of a laboratory bioreactor is employed and tested in order to describe the advantages and limitations.

Comparison of the sensitivity of Pseudomonas aeruginosa to disinfectants according to the growth conditions

Abstract During the evaluation of the bactericidal effect of some disinfectants, the authors observed major differences of sensitivity in the case of Pseudomonas aeruginosa depending on the culture medium used for the preparation of the inoculum. In particular for chloroxylenol the results were much more favourable when the culture was made in brain heart infusion (Difco) than in tryptic soy broth (Difco).

Influence of protamine on the in vitro sensitivity of Pseudomonas aeruginosa to antibiotics

We have studied the influence of protamine on the sensitivity of three strains of Pseudomonas aeruginosa to various antibiotics: streptomycin, gentamicin, polymyxin B, and beta-lactams. While protamine enhanced the antibacterial action of beta-lactams towards P. aeruginosa, it did not alter the effect of aminoglycosides. The antibacterial power of polymyxin B, on the other hand, was drastically reduced. The observed changes in this strains sensitivity to antibiotics could be due to changes in the permeability of the outer membrane.

Phage typing of coagulase-negative staphylococci

Seventy‐nine staphylococcal strains isolated from blood cultures (57 coagulase‐negative staphylococci (CNS) and 22 S. aureus) and 308 CNS isolated from the skin of healthy donors were phage typed. S. epidermidis and S. capitis were readily typed with 91 strains out of 124 and 24 strains out of 43 strains being successful. Species such as S. haemolyticus, S. hominis and S. simulans could be moderately phage typed. Others gave only a few strains capable of being typed, such as S. saprophyticus and S. sciuri. Under our experimental conditions the S. warneri, S. xylosus and S. cohnii could not be typed with our set of phages.