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Biomedical subjects

Jean Freney

Publications and source records attributed to Jean Freney.

17 recordsLinked to original sources
PubMed2006

Pacifiers: a microbial reservoir.

The permanent contact between the nipple part of pacifiers and the oral microflora offers ideal conditions for the development of biofilms. This study assessed the microbial contamination on the surface of 25 used pacifier nipples provided by day-care centers. Nine were made of silicone and 16 were made of latex. The biofilm was quantified using direct staining and microscopic observations followed by scraping and microorganism counting. The presence of a biofilm was confirmed on 80% of the pacifier nipples studied. This biofilm was mature for 36% of them. Latex pacifier nipples were more contaminated than silicone ones. The two main genera isolated were Staphylococcus and Candida. Our results confirm that nipples can be seen as potential reservoirs of infections. However, pacifiers do have some advantages; in particular, the potential protection they afford against sudden infant death syndrome. Strict rules of hygiene and an efficient antibiofilm cleaning protocol should be established to answer the worries of parents concerning the safety of pacifiers.

Analysis of Variance↗
PubMed2006

Characterization of the Legionella anisa population structure by pulsed-field gel electrophoresis.

We analysed 38 French isolates of Legionella anisa by means of pulsed-field gel electrophoresis (PFGE) with single or double digestion. Double digestion was more discriminatory than single digestion, and can thus be useful for epidemiological studies of L. anisa. Several isolates from different parts of France clustered together on the basis of their PFGE patterns (similarity cutoff of 80%), suggesting that the L. anisa population structure is homogenous or that a few clones of L. anisa strains have spread widely in France.

Electrophoresis, Gel, Pulsed-Field↗
PubMed2006

A novel in vitro model to study staphylococcal biofilm formation on intraocular lenses under hydrodynamic conditions.

PURPOSE: To develop a novel in vitro model to study the formation of Staphylococcus epidermidis biofilm on intraocular lenses (IOLs) from the primary-attachment phase to the biofilm-accumulation phase. The model was designed to replicate intraocular conditions especially by taking into account intraocular hydrodynamics. METHODS: The model consisted of Tygon tubing connected to a vial containing acrylic hydrophobic IOLs. Three septa, placed along the tubing, allowed, respectively, the artificial aqueous humor's arrival and its elimination and the bacterial suspension's inoculation. A first pump allowed the aqueous humor's movement along the circuit, whereas a second one regulated the flow at which the nutritive environment was regenerated. The whole circuit was placed in a 34 degrees C water bath. Every 2 to 4 hours, lenses were taken from this environment. Bound bacteria were removed by scraping of optical faces and counted. All data are presented as the mean, SD, and coefficient of variation (CV). Comparisons among experiments were performed by one-way analysis of variance (ANOVA). RESULTS: Calculated CVs were close to 30, showing that biofilm formation was homogeneous. Differences between experiments were nonsignificant for each removal time. The model provided the full kinetics of S. epidermidis biofilm growth on acrylic hydrophobic IOLs, with a stationary phase reached after 28 hours of incubation. CONCLUSIONS: Biofilm development is modulated by many variables, including environmental factors. The findings in the present study of bacterial colonization of IOLs under intraocular physiological conditions allow understanding and more accurate targeting of biomedical device-related infections such as endophthalmitis.

Acrylic Resins↗
PubMed2005

A new procedure allowing the complete removal and prevention of hemodialysis biofilms.

Most currently used disinfectants for dialysis machines have a good bactericidal efficacy on biofilms but leave dead cells on the surface. This contributes to the regrowth of biofilm and the release of pyrogens. A new anti-biofilm procedure consisting of sequential treatment combining enzymes and detergents is able to detach adherent cells. The efficacy of this procedure was assessed both in vitro and in reality. For in vitro studies, a biofilm model was set up. Studies were also performed in reality in a clinically used dialysis machine. Biofilm removal was first monitored by image analysis. Then, the biomass was detached by scraping and quantified by plate counts and endotoxin level measurement. Treated samples were compared to untreated control samples. The procedure led to the complete detachment of the biomass, both in vitro and in the reality situation. The aim of this procedure is to replace or complete the usual disinfection methods for medical devices.

Bacterial Adhesion↗
PubMed2005

In vitro influence of vancomycin on adhesion of a Staphylococcus epidermidis strain encoding intercellular adhesion locus ica to intraocular lenses.

PURPOSE: To assess anti-adhesion and/or bactericidal properties of vancomycin in vitro and to determine when these effects are detectable to estimate its relevance to perioperative antibiotic prophylaxis and analyze the efficacy of a newly designed vancomycin insert prototype for endophthalmitis prevention. SETTING: University research laboratory, Lyon, France. METHODS: Staphylococcus epidermidis clinical strain N890074 containing the intercellular adhesion locus ica was used as the infectious agent. Vancomycin was used at 20 microg/mL. A sterile biocompatible, biodegradable vancomycin insert, releasing 230 microg of antibiotics over 100 minutes, was designed especially for this study. To obtain bacterial killing curves, experiments were first performed in a 103 colony-forming units (CFU/mL) bacterial suspension containing no intraocular lenses (IOL). Then IOLs were incubated in the suspension, and bacterial adherence was determined using bacterial counting with and without antibiotic. RESULTS: Vancomycin (solution and insert) had an anti-adhesion effect after 1 hour and a relevant bactericidal effect after 6 hours of incubation. CONCLUSIONS: Vancomycin used with irrigating solutions does not remain in the anterior chamber long enough to develop bactericidal effect. Even if it initially reduces bacterial adhesion, used at a drug level dropping below the bacterial minimal inhibitory concentration, it could result in a secondary increase of the adhesion of slime-producing bacteria. A sufficiently high concentration was obtained in vitro by the new sustained-release system, thereby overcoming the theoretical drawback of a short half-life within the anterior chamber. Anti-adhesion and bactericidal action of vancomycin inserts remains to be confirmed in clinical studies.

Anti-Bacterial Agents↗
PubMed2005

Antibacterial activity of clonidine and neostigmine in vitro.

We conducted an in vitro study to investigate the antibacterial activity of clonidine and neostigmine on common microorganisms encountered during infectious complications after regional anesthesia. Standardized suspensions of Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli were incubated during 1, 3, 6, and 24 h at 37 degrees C with concentrations of 37.5, 75, and 150 microg/mL of clonidine and 125, 250, and 500 microg/mL of neostigmine. After 24 h incubation at 37 degrees C, the colony counts were compared by two-way analysis of variance. The mean colony counts for S. aureus decreased significantly from control as the exposure to clonidine increased (P < 0.05), with a approximately 100% kill at 6 h for the largest concentration (150 microg/mL) and at 24 h for the intermediate concentration (75 microg/mL). Similar results were observed for S. epidermidis, with a approximately 100% kill at 6 h for the largest concentrations (75 and 150 microg/mL). No bactericidal activity of clonidine was observed for E. coli and no bactericidal activity of neostigmine was observed for any of the tested strains. In the conditions of this experiment, clonidine, but not neostigmine, exhibited a concentration-dependent and time-dependent bactericidal activity in vitro on the microorganisms most frequently encountered in infectious complications after regional anesthesia.

Anesthesia, Conduction↗
PubMed2004

Pyrolysis patterns of 5 close Corynebacterium species analyzed by artificial neural networks.

In the present study, an artificial neural network was trained with the Stuttgart Neural Networks Simulator, in order to identify Corynebacterium species by analyzing their pyrolysis patterns. An earlier study described the combination of pyrolysis, gas chromatography and atomic emission detection we used on whole cell bacteria. Carbon, sulfur and nitrogen were detected in the pyrolysis compounds. Pyrolysis patterns were obtained from 52 Corynebacterium strains belonging to 5 close species. These data were previously analyzed by Euclidean distances calculation followed by Unweighted Pair Group Method of Averages, a clustering method. With this early method, strains from 3 of the 5 species (C. xerosis, C. freneyi and C. amycolatum) were correctly characterized even if the 29 strains of C. amycolatum were grouped into 2 subgroups. Strains from the 2 remaining species (C. minutissimum and C. striatum) cannot be separated. To build an artificial neural network, able to discriminate the 5 previous species, the pyrolysis data of 42 selected strains were used as learning set and the 10 remaining strains as testing set. The chosen learning algorithm was Back-Propagation with Momentum. Parameters used to train a correct network are described here, and the results analyzed. The obtained artificial neural network has the following cone-shaped structure: 144 nodes in input, 25 and 9 nodes in 2 successive hidden layers, and then 5 outputs. It could classify all the strains in their species group. This network completes a chemotaxonomic method for Corynebacterium identification.

Algorithms↗
PubMed2004

Clinical and environmental distributions of Legionella strains in France are different.

In France, the clinical distribution of Legionella species and serogroups does not correspond to their environmental distribution. Legionella pneumophila serogroup 1 is more prevalent among clinical isolates (95.4%) than in the environment (28.2%), whereas L. anisa is more frequent in the environment (13.8%) than in the clinical setting (0.8%).

France↗
PubMed2003

Biofilm formation on intraocular lenses by a clinical strain encoding the ica locus: a scanning electron microscopy study.

PURPOSE: To determine whether the Staphylococcus epidermidis strain carries the intercellular adhesion (ica) locus, which encodes production of adhesins mediating adherence to biomaterials and to study, with scanning electron microscopy, the morphologic features of this coagulase-negative Staphylococcus strain that adheres to intraocular lenses (IOLs). METHODS: Polymerase chain reaction amplification was used to investigate whether the isolate under study (S. epidermidis clinical strain N890074) carries the ica locus. Sterile intraocular lenses (IOLs) were incubated in bacterial suspension either for 5 minutes or 1 hour. IOLs were then examined by scanning electron microscopy. RESULTS: Polymerase chain reaction amplification revealed that S. epidermidis N890074 contained the ica locus. The bacteria appeared to be anchored to the surface of the lenses by several different means-particularly by leglike appendages and a slime layer-which probably came into play step by step. CONCLUSIONS: For the first time in ophthalmology, to the authors' knowledge, photographs showing leglike appendages involved in the first phase of adhesion have been obtained. They also clearly visualize the slime layer containing the embedded bacteria. This study provides information about the nature and the genesis of these attachment processes. Adherence is known to be greater when the bacterial DNA contain the ica locus. Full knowledge of the pathogenesis of bacterial adhesion is necessary to gain a better understanding of IOL infection and endophthalmitis.

Adhesins, Bacterial↗
PubMed2003

Bacterial adherence of Staphylococcus epidermidis to intraocular lenses: a bioluminescence and scanning electron microscopy study.

PURPOSE: To analyze and compare the adherence of Staphylococcus epidermidis to intraocular lenses (IOLs) made of five different biomaterials (native or heparinized polymethylmethacrylate, silicone, hydrophilic acrylic, or hydrogel) and to detail the different steps and mechanisms of bacterial adhesion to a polymer. METHODS: A clinical strain carrying the intercellular adhesion (ica) locus was used. In a previous study, the extent of bacterial binding was measured by counting. In this study, two different techniques, bioluminescence and scanning electron microscopy (SEM), were used to analyze the accuracy of each one, to obtain a comparison between the various IOLs, and to complete previous observations. The results were compared using both the Kruskal-Wallis and the Mann-Whitney nonparametric tests. RESULTS: Bacterial adhesion was statistically weakest on hydrogel and then on hydrophilic acrylic polymer. Adhesion depended on the hydrophobicity or hydrophilicity of the biomaterials. Slight differences were found between the two methods, and these differences are explained. Furthermore, SEM observations highlighted two different patterns of bacterial adhesion (isolated bacteria and clusters of bacteria), assuming that hydrophobic IOLs (silicone and PMMA) probably facilitate bacterial colonization and biofilm production. CONCLUSIONS: Attachment mechanisms may be different in each case, depending on the polymer material and the infecting organism, because there are various types of behavior among S. epidermidis strains. Hydrophilic polymer surfaces (hydrogel and probably hydrophilic acrylic) seem to be useful in avoiding the development of bacterial colonies and hence in preventing endophthalmitis. Fewer bacteria were attached, demonstrating inhibition or delay in bacterial colonization.

Acrylic Resins↗
PubMed2002

Differentiation of Corynebacterium amycolatum, C. minutissimum, C. striatum and related species by pyrolysis-gas-liquid chromatography with atomic emission detection.

We report here the application of pyrolysis-gas chromatography followed by atomic emission detection (AED) for the characterisation of Corynebacterium amycolatum and related species (i.e., C. striatum, C. minutissimum, C. xerosis and the recently described C. freneyi). This phenotypic method, which analyses the whole chemical composition of bacteria, clearly separates C. amycolatum from other species. Moreover, this C. amycolatum group is subdivided into two distinct subgroups. We cannot differentiate the C. minutissimum strains from those of C. striatum. On the other hand, C. freneyi and C. xerosis are clearly distinct from the other species.

Bacterial Typing Techniques↗
PubMed2002

Identification of Legionella species by ribotyping and other molecular methods.

There are currently more than 40 species of Legionella and the identification of most of them by standard methods is often technically difficult. The aim of this study was to use a ribotyping method with endonuclease HindIII and a probe consisting of a set of five oligonucleotides (referred to as OligoMix5). A total of 123 strains, including 78 type or reference strains corresponding to 44 species, eight clinical and 37 environmental isolates were tested. The usefulness of the method was demonstrated for the identification at the species level of all of the 123 Legionella isolates tested, with each species showing a specific profile. Among the 15 serogroups of Legionella pneumophila, eight patterns were obtained. For the 45 field strains, the randomly amplified polymorphic DNA (RAPD) technique and intergenic 16S-23S ribosomal spacer PCR analysis (ITS 16-23S) were also used. Altogether, these three methods allowed the identification of all of strains tested. However, ribotyping has proven to be more effective than the other methods.

Environmental Microbiology↗
PubMed2002

In-vitro study of bacterial adherence to different types of intraocular lenses.

The aim of this study was to determine the adherence of Staphylococcus epidermidis to intraocular lenses made of five different biomaterials: polymethylmethacrylate (PMMA), heparinized PMMA, silicone, hydrophilic acrylic, and hydrogel. The extent of bacterial binding was measured by counting. The results were compared using a one-factor variance analysis. Adherence was weakest on hydrogel and strongest on the silicone polymer. Bacterial adherence to the implant surface must therefore depend on the hydrophobicity or hydrophilicity of the biomaterial.

Acrylates↗
PubMed2002

Population diversity of Staphylococcus intermedius isolates from various host species: typing by 16S-23S intergenic ribosomal DNA spacer polymorphism analysis.

Twelve 16S-23S ribosomal DNA intergenic spacer (ITS-PCR) types were identified among 57 Staphylococcus intermedius isolates from humans and other animals. Six ITS-PCR types were host specific, and most human and canine strains belonged to the same types (A and J). Pigeon, horse, and mink strains appeared more heterogeneous.

Animals↗
PubMed2002

In vivo study of bacterial adhesion to five types of intraocular lenses.

PURPOSE: To determine in vivo behavior of the ability of the Staphylococcus epidermidis strain (American Type Culture Collection [ATCC] 14990) to attach to 120 intraocular lenses (IOLs) made of five different biomaterials: fluorine polymethylmethacrylate (PMMA), heparinized PMMA, silicone, hydrophobic acrylic, and hydrogel. The pig was chosen as an animal model of endophthalmitis, after a bibliographical analysis and a personal study of its aqueous humor composition. METHODS: Crystalline lenses from 90 domestic pigs were removed aseptically and replaced with previously infected IOLs. The animals were killed 24 hours, 72 hours, and 1 week after implantation of the IOLs. The extent of bacterial binding was then measured by counting. Results were compared with a two-factor analysis of variance (ANOVA 2), confirmed by the Kruskal-Wallis nonparametric test. RESULTS: The extent of bacterial binding (expressed as bound bacteria per area unit) was found to range in increasing order from hydrogel, to fluorine PMMA, to hydrophobic acrylic, to heparinized PMMA, to silicone polymer. Comparison of pairs of materials showed statistically significant differences, except between hydrogel and fluorine PMMA. CONCLUSIONS: To the authors' knowledge, no study has been published so far concerning the in vivo evolution of populations of bacteria adhering to different intraocular materials. Bacterial adhesion to the implant surface must therefore depend on the hydrophobicity or hydrophilicity of the biomaterial. Adhesion is also affected by the nature of the surrounding medium. Because of its complexity, the latter appears to be very difficult to model, thus making in vivo studies essential.

Acrylic Resins↗
PubMedDate not supplied

[Armauer Hansen (1841-1912), portrait of a Nordic pioneer].

Desending from a Danish family, Gerhard Henrik Armauer Hansen was born in Bergan, Norway, on 29 July, 1841. Graduated in medicine in 1866 from the University at Christiana (the former name of Oslo), he started his medical career as an assistant physician at the National Hospital of Oslo for one year, working afterwards as a medical officer for a fishing company outside the Arctic Circle. Taking not well his routine job, he soon returned to Bergen where he began his work on a disease known as leprosy at the age of 26 and as an assistant of D.C. Danielssen at the Lungegaarden Hospital. There he engaged in research and investigations on the nature of the disease. Studying the various types of leprosy (skin, nerve and visceral lesions), he was awarded, one year after beginning his work, the gold metal of the University for his first publication on the disease. While Danielssen leaned toward heredity as a dominant factor in leprosy, Hansen's conviction was that the disease must have an infectious causal agent. In about 1871, Hansen began to observe tiny little rods in tissue specimens and considered they could be the ethiologic agent of leprosy, the more he found these rods in all the infiltrated nodular lesions in his patients. Finally, he proposed on February 28, 1873, that the rods were bacilli, responsible of leprosy. Promoted to the rank of Chief of the Leprosy Service in 1875, he held his job for 37 years; Hansen's entire adult life was spent at work in leprosy. He edited the journal < >. Hansen was also an eminent zoologist engaged in studies involving mollusks and worms; Since 1874, he was president of the Bergen Museum of Natural History. Armauer Hansen died on February 12, 1912, and the funeral ceremonies took place in the Museum of Bergen where his ashes are still kept.

Bacteriology↗