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Biomedical subjects

P Maris

Publications and source records attributed to P Maris.

At least 19 recordsLinked to original sources
PubMed2005

Screening of benzalkonium chloride resistance in Listeria monocytogenes strains isolated during cold smoked fish production.

AIMS: To determine the susceptibility to disinfectants and cross-resistance to antibiotics in Listeria monocytogenes strains isolated from fish products and the fish-processing environment. METHODS AND RESULTS: Minimal inhibitory concentration assessment, using the agar dilution method, showed 108 of 255 L. monocytogenes isolates with low susceptibility to benzalkonium chloride (BC), commonly used in food industries. Most of them are from raw products of farmed fish during processing, while the remaining resistant isolates were mainly from the environment and finished products irrespective of the fish species. Two BC-resistant isolates were resistant to ethidium bromide (EB). The conservation of resistance after plasmid curing suggested that the resistance genes are not plasmid associated. EB accumulation assays demonstrated that the two BC(R) EB(R) isolates used an efflux pump to expel these substrates whereas a different mechanism was probably used by the majority of the strains with BC(R) EB(S) pattern. No cross-resistance was found with antibiotics. CONCLUSIONS: This study highlights the difference in susceptibilities to BC for L. monocytogenes strains isolated from fish-processing plants and in resistance mechanisms to BC developed by these bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of BC resistant L. monocytogenes strains could contribute to their adaptation and so explained their survival and persistence in the fish-processing environment.

Anti-Bacterial Agents↗
PubMed2004

Validation of a microbiological method: the STAR protocol, a five-plate test, for the screening of antibiotic residues in milk.

The results of an in-house laboratory validation of a microbiological method for the screening of antibiotic residues in milk are presented. The sensitivity of this five-plate test, called Screening Test for Antibiotic Residues (STAR), was established by the analysis of milk samples spiked with 66 antibiotics at eight different concentrations. Ten different groups of antibiotics were studied: macrolides, aminoglycosides, cephalosporins, penicillins, quinolones, tetracyclines, sulphonamides, lincosamides, phenicolated and miscellaneous drugs. It was shown that 21 antibiotics were detected by the STAR protocol at or below the maximum residue limit (MRL), and that a further 27 drugs could be detected at levels from the MRL up to four times the MRL. The sensitivity of the STAR protocol was at or below the MRL for three macrolides, one tetracycline, two aminoglycosides, some sulphonamides, half of the beta-lactams, quinolones, lincosamides, trimethoprim and baquiloprim. Moreover, the STAR protocol was at least twice as sensitive as conventional methods for macrolides, quinolones and tetracyclines. The other antibiotics had limits of detection between four and 150 times the MRL. Each plate was preferentially sensitive for one or two families of antibacterials: the plate Bacillus cereus for tetracyclines, the plate Escherichia coli for quinolones, the plate Basillus subtilis for aminoglycosides, the plate Kocuria varians for macrolides, and the plate Bacillus stearothermophilus for sulphonamides and beta-lactams. This method has been used routinely on a day-to-day basis to direct the physicochemical confirmation towards one or two families of antibiotics. Considering the high cost of liquid chromatography coupled with tandem mass spectrometry detection analyses, the reduction of the range of antibiotics to test for confirmation is a significant gain in time and money.

Animals↗
PubMed1999

Measurement of the residual contamination of post-weaning facilities for pigs and related risk factors.

A survey was designed in France to assess residual contamination in post-weaning rooms within the 2 h prior to restocking when all the pigs of the previous batch had been removed (all in-all out) and after application of the 'in use' cleaning procedures. The protocol was based on the results of a pilot study and was considered 'a good compromise'. Special agar plates (Rodac plates) with a prominent agar medium surface were prepared and used to collect the bacteria. They were applied by impression onto the floors and the partitions between the pens. In all, 24 plates were applied per room. The culture medium was VRBG which mainly permits the growth of enterobacteria. The plates were incubated for 24 h (37 degrees C) and the Colony-Forming Units (CFU) counted. After sampling, measurements were made and information collected from the farmer to obtain potential explanations for the resulting microbiological data. The same scientist sampled 129 post-weaning rooms with slatted floors. Of the 3045 plates, 18.4% were negative and 12.8% were heavily colonized (> 300 CFU). A score combining six criteria based on the counts was produced, and indicated a wide spread of the rooms. The profile of circumstances associated with the different levels of the score was extracted. The following points should be respected to achieve low residual contamination: removal of the slurry from the pit below the slatted floor; damping to be started soon after pig removal; prolonged damping; thorough washing; disinfecting soon after washing; and attention to the recommended dosage of disinfectant. Smooth surfaces were found to be less contaminated than rough ones. It is concluded that cleaning and disinfecting operations must not be considered as minor tasks and should clearly be integrated into the process of pig production.

Animals↗
PubMed1998

Results of a European interlaboratory study for the determination of oxytetracycline in pig muscle by HPLC.

An interlaboratory study was organised in 1996 in order to determine laboratory testing performance for measuring oxytetracycline (OTC) and 4-epioxytetracycline (4-epiOTC) residues in pig muscle. The organisation was designed according to the 'International Harmonised Protocol for Proficiency Testing of (Chemical) Analytical Laboratories' produced by the Association of Official Analytical Chemists (AOAC International) and the International Union of Pure and Applied Chemistry (IUPAC). Fourteen National Reference Laboratories (NRLs) out of the 15 asked to participate agreed to analyse the samples. These laboratories were from 13 different European Union (EU) Member States and each participant was allowed to use the extraction method of their own choice but had to use liquid chromatography as the analytical technique. Most of the methods used were based on UV detection (simple wavelength or diode-array detection) but some involved fluorimetric detection. The production of incurred samples was prepared on-site. The OTC and 4-epiOTC concentrations present in the samples were determined by taking the mean of the results (excluding outliers) and the deviation of each result from the assigned value was measured. The performance of the laboratories was evaluated by calculating the 'z-scores'. The results were globally satisfactory and showed that all 14 laboratories were capable of determining OTC and 4-epiOTC in pig muscle with satisfactory accuracy. Only two laboratories obtained a questionable result in terms of repeatability.

Animals↗
PubMed1995

Modes of action of disinfectants.

The exact mechanism of action of a disinfectant is not easy to elucidate. The notion of 'target' in the bacterial cell, frequently evoked for the antibiotics, is not clear for disinfectants (except for some, e.g. chlorhexidine). In understanding the mode of action of a disinfectant, it can be difficult to distinguish the primary stage (characteristic of the mode of action) and the secondary stage (consequence of the action). The author describes the actions of disinfectants on the external membrane, cytoplasmic membrane and energy metabolism of cells; these actions include rupture of the membrane, loss of permeability and coagulation of the cytoplasm.

Bacteria↗
PubMed1995

[Antiseptic and antibiotic resistance of 310 gram-positive strains isolated from udders after use of post-milking teat germicides].

The sensitivity of 310 Gram-positive strains, isolated from milking cows udders, to 4 antiseptics (cetrimide, chlorhexidine, hexachlorophene and mercury) and 9 antibiotics (ampicillin, streptomycin, erythromycin, chloramphenicol, kanamycin, tetracycline, gentamycin, novobiocin and oxacillin) was determined. The statistical analysis of correlation was carried out for the bacterial species studied (Staphylococcus, Streptococcus and Bacillus), the scattering of the minimum inhibitory concentrations of which has proved to be statistically heterogeneous towards antiseptics and antibiotics. This analysis revealed positive links between chlorhexidine and 5 antibiotics for Streptococcus and between hexachlorophene and oxacillin for Bacillus. The analysis of results at the level of bacterial species, taking into account a loss of sensitivity of 4 times the modal minimum inhibitory concentration of the species reveals the importance of the strains which are resistant to many antibiotics and especially the Enterococcus and the species Staphylococcus epidermidis. Indeed, these strains are possible reservoirs of plasmids of resistance to antibiotics and antiseptics.

Animals↗
PubMed1993

[Study of combinations of antimicrobial agents. Development of the method].

We developed and validated a micromethod similar to the checkerboard method in antibiotherapy to study the efficiency of antiseptic and disinfectant molecules. The determination of the FBC index (Fractional Bactericidal Concentration) on 4 reference strains (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus hirae) for 4 associations (2-benzyl-4 chlorophenol--iodophor; cetrimide-iodophor, 2 benzyl-4 chlorophenol--formaldehyde; hexamidine--formaldehyde) revealed 2 synergistic associations and 2 antagonistic associations for one or more strains.

Anti-Bacterial Agents↗
PubMed1991

[Resistance of 700 gram-negative bacterial strains to antiseptics and antibiotics].

The sensitivity of 701 Gram negative strains, representing 16 species or bacterial genera, towards 4 antiseptics (cetrimide, chlorhexidine, hexachlorophene, mercuric chloride) and 6 antibiotics (ampicillin, streptomycin, erythromycin, chloramphenicol, kanamycin, tetracycline) was analysed. For 3 antiseptics (cetrimide, chlorhexidine, mercuric chloride) minimal inhibitory concentration distribution showed strains to be heterogeneous, particularly in the group Pseudomonas. Most strains were resistant to antibiotics. The statistical analysis of correlation showed positive resistance links between antiseptics (cetrimide, chlorhexidine, hexachlorophene) or between these antiseptics and antibiotics for S marcescens and Alcaligenes. Many strains proved resistant, at the same time, to mercuric chloride and to several antibiotics. These associations of resistance suggest either a common mechanism of action or a crossed resistance.

Anti-Bacterial Agents↗
PubMed1990

[The in vitro activity of veterinary antiseptics].

The in vitro activity of 28 veterinary antiseptic drugs was studied on 4 bacterial strains either with or without calf serum. Eight preparations (VT Dose, Dulcidrine, Collyre Clément, Cronic, Detecaïne, Lotion Maudor, Tano-Patt, Aurikan), half of which were eye-lotions, were found to be non antiseptic according to AFNOR standards. In the presence of calf serum, 4 other preparations (Albacetine, Nybocaïne, Pediplasme, Pedifort) did not meet the standard NF T 72.171 criteria.

Animals↗
PubMed1990

[Virucidal efficacy of eight disinfectants against pneumovirus, coronavirus and parvovirus].

The virucidal activity of 8 disinfectants was analyzed towards 3 groups of viruses responsible for diseases in animals (pneumovirus, coronavirus, parvovirus). Whether organic matter is present or not, parvoviruses are the most resistant, since concentrations of disinfectants 20-500 times higher than those inactivating coronaviruses and pneumoviruses must used. When organic matters are present the activity of disinfectant is considerably reduced. Among the products tested, 0.8% soda and sodium hypochlorite with 1 degree chlorometric were the most active.

Animals↗
PubMed1990

[Control of disinfection in the buildings of pig farms].

A survey carried out in pig farms was undertaken in order to compare 4 disinfectants used in 13 disinfecting operations, during the vacation period. It was immediately noticeable that after swabbing and counting the staphylococci, the chloramine T-based preparation was more effective than the quaternary ammonium-aldehyde association, phenolic acid derivatives or the quaternary ammonium preparations. We then observed that although the number of organisms decreased by 99.8%, their number on slatted floors still ranged between 0.02 x 10(4) and 3 x 10(4) per cm2.

Animals↗