Reliability of Pseudomonas aeruginosa semi-automated rep-PCR genotyping in various epidemiological situations.

The purpose of this study was to evaluate the possibility of using a semi-automated repetitive DNA sequences-based polymerase chain reaction (rep-PCR) for typing Pseudomonas aeruginosa isolates. rep-PCR profiles obtained by the DiversiLab system of 84 P. aeruginosa isolates from distinct epidemiological situations were obtained. rep-PCR groupings were in good agreement with the origin of these isolates. Linked rep-PCR profiles were observed for isolates recovered from a same family of cystic fibrosis (CF) patients, for the etiological agents of clustered cases of nosocomial infections, and for some isolates recovered from a same hospital room. rep-PCR and pulsed-field gel electrophoresis SpeI restricted genomic DNA (PFGE-SpeI) profiles were compared. In a few instances, rep-PCR revealed genetic divergences among isolates of a same group of PFGE-SpeI profiles. These divergences could reflect genetic drifts among closely related isolates, as illustrated by those observed between clinical and environmental isolates of a same group of PFGE-SpeI profiles. The interpretation of such differences will require further studies, but the rep-PCR analysis of P. aeruginosa diversity appeared to be an appropriate method to investigate infra-specific genetic relatedness.

Validation of a viral and bacterial inactivation step during the extraction and purification process of porcine collagen.

In the last few years, regulations for biomolecule production, and especially for extraction and purification of animal molecules such as collagen, have been reinforced to ensure the sanitary safety of the materials. To be authorized to market biomaterials based on collagen, manufacturers now have to prove that at least one step of their process is described in guidelines to inactivate prion, viruses, and bacteria. The present study focuses on the inactivation step performed during the extraction and purification of porcine type I atelocollagen. We chose to determine the reduction factor of a 1 M NaOH step on porcine parvovirus and four bacterial strains inactivation. During the extraction step, we deliberately inoculated the collagen suspension with the different microorganisms tested. Then, 1 M NaOH was added to the suspension for 1 hour at 20 degrees C. We demonstrated that this treatment totally inactivated S. aureus, P. aeruginosa, C. albicans and A. niger which are bacterial strains responsible of severe human pathology. The reduction factors reached more than 4 logs for B. cereus spores and 4 logs for the porcine parvovirus. are encouraging as those two microorganisms are known to be very resistant to inactivation.

Degradation of paraoxon (VX chemical agent simulant) and bacteria by magnesium oxide depends on the crystalline structure of magnesium oxide.

In this work, our goal was to study the capability of a single metallic oxide to neutralize a chemical agent and to exhibit an antibacterial effect. We tested two types of magnesium oxides, MgO. The first MgO sample tested, which commercial data size characteristic was -325 mesh (MgO-1) destroyed in 3 h, 89.7% of paraoxon and 93.2% of 4-nitrophenol, the first degradation product. The second MgO sample, which commercial data size was <50 nm (MgO-2) neutralized in the same time, 19.5% of paraoxon and 10.9% of 4-nitrophenol. For MgO-1 no degradation products could be detected by GC-MS. MgO-1 had a bactericidal activity on Escherichia coli (6 log in 1 h), and showed a decrease of almost 3 log on a Staphylococcus aureus population in 3 h. MgO-2 caused a decrease of 2 log of a E.coli culture but had no activity against S. aureus. Neither of these two products had an activity on Bacillus subtilis spores. Analytical investigations showed that the real sizes of MgO nanoparticles were 11 nm for MgO-1 and 25 nm for MgO-2. Moreover, their crystalline structures were different. These results highlighted the importance of the size of the nanoparticles and their microscopic arrangements to detoxify chemical products and to inhibit or kill microbial strains.

Using an efficient biofilm detaching agent: an essential step for the improvement of endoscope reprocessing protocols.

Biofilms develop inside endoscope channels even when valid endoscope reprocessing protocols are applied. The use of an efficient biocide is not sufficient if the channels are not cleaned thoroughly prior to disinfection. This study compared new anti-biofilm combinations of detachment promoting agents with a cleaning product in current use. Tests were performed using Teflon tubing and a contamination device that reproduces conditions that are prevalent during endoscopy. Products were subjected to static+brushing or dynamic treatments, and their ability to remove a preformed biofilm was assessed. The residual biofilm after treatment was assessed and compared with untreated controls. The percentage of surface covered by biofilm was measured after staining with crystal violet. Culturable bacteria levels were determined by plating the bacteria scraped from the tubing surface and counting the colony-forming units (CFU). Further tests were performed on actual endoscopes that had been contaminated artificially. Biofilm removal was confirmed by scanning electron microscopy. This study showed that the new anti-biofilm products prevented the build-up of biofilm and removed a mature biofilm (approximately 10(8)CFU/cm(2)), whereas protocols based on detergent-disinfectants containing quaternary ammonium compounds showed low efficacy as these protocols and products fixed the biofilm on the endoscope surfaces. The new procedure and agents represent a new approach to biofilm control that may improve the efficacy of endoscope reprocessing, and reduce the risk of transmitting infections.

[Staphylococcus epidermidis biofilms on intraocular lens surface: review of the literature]. / Biofilms à Staphylococcus epidermidis à la surface des implants intraoculaires.

Bacterial adhesion to intraocular lenses (IOLs) takes place during their implantation. This is a prominent etiological factor of postoperative endophthalmitis. Following adhesion, secretion of an extracellular matrix (called slime for Staphylococcus epidermidis) and formation of multiple layers of microcolonies lead to the colonization of the biomaterial surface. Scanning electron microscopy photographs illustrate the different steps of biofilm formation. The different adhesins expressed by S. epidermidis involved in the adhesion process are described. The biofilm is not only an adhesive medium; it also affects virulence. Last, notions on biofilm physiology are discussed in an attempt to explain the dynamic equilibrium of this system. In 2004, the perfect biomaterial able to prevent postoperative endophthalmitis does not yet exist. Moreover, there is no effective tool, at the present time, to fight against mature biofilms. Therefore, preventing biofilm formation remains capital, which requires perfect knowledge of all stages of formation and the factors involved.

Essential oils: from extraction to encapsulation.

Essential oils are natural products which have many interesting applications. Extraction of essential oils from plants is performed by classical and innovative methods. Numerous encapsulation processes have been developed and reported in the literature in order to encapsulate biomolecules, active molecules, nanocrystals, oils and also essential oils for various applications such as in vitro diagnosis, therapy, cosmetic, textile, food etc. Essential oils encapsulation led to numerous new formulations with new applications. This insures the protection of the fragile oil and controlled release. The most commonly prepared carriers are polymer particles, liposomes and solid lipid nanoparticles.

Intraocular lenses, bacterial adhesion and endophthalmitis prevention: a review.

Postoperative endophthalmitis following intraocular lens (IOL) implantation is still one of the most feared complications of cataract surgery. Bacterial adhesion to IOLs during their insertion is a prominent etiological factor. Polypropylene was the first biomaterial that allowed this relation of cause and effect to be proven. Following adhesion, bacteria replicate, congregate and form multiple layers of microcolonies which actually represent the basic structural unit of the biofilm. The bacteria are embedded in a slime layer. Personal photographs illustrate the different steps of biofilm formation. This slime matrix is not only an adhesive medium; it also affects virulence. Adhesion to IOLs has been studied by several in vitro studies and discrepancies can be found between them which are due to variations of experimental conditions. The strains, the incubation times and the methods all varied. Adhesion is affected by the nature of the IOLs, the isolates and the surrounding medium. Since this medium is very difficult to model because of its complexity, in vivo studies seemed essential. We have recently determined in vivo evolution of the amount of attached bacteria to five types of IOLs. Crystalline lenses from 90 domestic pigs were removed aseptically and replaced with previously infected IOLs. There have been few epidemiological studies published to determine the relationship between endophthalmitis and the IOL type. However, the perfect biomaterial that could prevent postoperative endophthalmitis does not yet exist. Globally, hydrophilic materials and hydrophobic acrylic seem to be less sticky than silicone or PMMA, but this remains to be proven clinically.

Levobupivacaine hydrochloride and sufentanil have no antimicrobial effect at 25 degrees C in vitro.

BACKGROUND AND OBJECTIVES: Levobupivacaine in combination with sufentanil may be used for labour or postoperative regional analgesia. The risk of bacterial growth within these contained solutions for several hours at room temperature is unknown. We investigated the in vitro antimicrobial effect of levobupivacaine and sufentanil against common micro-organisms encountered during regional anaesthesia. METHODS: Standardized suspensions of Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli were incubated for 1, 3, 6 and 24 h at 25 degrees C, with saline (as control), sufentanil 0.5 or 0.75 microg mL-1, levobupivacaine hydrochloride 5.6 mg mL-1 and concentrations of 1.4, 2.8 and 5 mg mL-1 of levobupivacaine hydrochloride with sufentanil 0.5 microg mL-1. Colony counts were compared after 24 h incubation at 37 degrees C. RESULTS: No bacterial growth was observed on any bacterial strain for any solution tested throughout the experiment. CONCLUSIONS: Our results suggest that solutions of levobupivacaine combined with sufentanil may be used for 24 h at room temperature during regional anaesthesia with no risk of bacterial growth.

Evaluation of the new Vitek 2 GN card for the identification of gram-negative bacilli frequently encountered in clinical laboratories.

The new Vitek 2 GN card (bioMérieux, Marcy-l'Etoile, France) was developed for better identification of fermenting and nonfermenting bacilli. This new card allows the identification of 159 taxa. A total of 426 isolates (331 fermenting and 95 nonfermenting gram-negative bacilli) belonging to 70 taxa covered by the database were evaluated. All isolates were identified in parallel with the ID 32 GN, the API 20E, and the API 20NE methods. The system correctly identified 97.4% (n=415) of the strains. Only 2.1% (n=9) needed additional testing. One strain (0.25%) was misidentified (Klebsiella pneumoniae subsp. pneumoniae), and another one (0.25%) was not identified (Morganella morganii subsp. morganii). The new GN card gives more accurate identifications overall for gram-negative bacilli when compared to the systems described in other similar studies.