Topical effects of a quaternary ammonium compound on caries incidence and bacterial agglomerate formation in the rat.
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An electrophoretic method for the simultaneous separation and determination of cationic and anionic surfactants based on double electrokinetic injection from the two ends of the capillary is proposed here. Nonaqueous capillary electrophoresis (NACE) with methanol as solvent was used to reduce the electroosmotic flow so that under these conditions the analytes migrate toward the corresponding electrode. The optimization step was the key to solve the problems associated with surfactants analysis (namely, adsorption on the capillary wall, micelle formation, and those issues related to the separation of homologous compounds). Good results were obtained with the proposed method both for the analysis of both spiked and natural samples, thus demonstrating the applicability of the proposed method for routine analysis. Finally, a comparison between the proposed method and two methods for independent analysis of cationic and anionic surfactants was made. The results showed that the precision (between 1.90 and 4.10% for repeatability and 7.43 and 8.98% for within-laboratory reproducibility, both expressed as relative standard deviation) and sensitivity (limits of detection and quantification between 0.52 and 1.88 microg/mL and between 1.73 and 6.20 microg/mL, respectively) are not affected by the CE mode. The resolution was similar to or better than that of the comparison methods and the analysis time was considerably shortened as both types of compounds were determined in a single run in only 9 min.
In-vitro and in-vivo models for testing the antibacterial activity of glove materials are described. The models were tested using four types of material: latex containing residual accelerator, latex treated by solvent-extraction to remove accelerator, material from hypo-allergenic accelerator-free gloves, and latex coated with quaternary ammonium compounds. In-vitro tests revealed two distinct types of antibacterial activity, one related to the accelerator which was slow-acting, and not neutralizable, and a second faster-acting neutralizable activity due to the quaternary ammonium compounds. The antiseptic coated material also showed antibacterial activity on human skin.
Two similar calici agents, San Miguel sea lion virus (SMSV) and vesicular exanthema of swine virus (VESV) are susceptible to the virucidal activity of disinfectants of differing formulation. Ten of 12 compounds were effective against six log10 plaque forming units (PFU) of SMSV in a 2-min exposure at 4, 25 and 37 degrees C. However, only seven of these 10 SMSV-positive compounds inactivated VESV under the same conditions of temperature and time. Two compounds were not effective against SMSV in a 20-min exposure at 4 and 25 degrees C, but were effective at 37 degrees C. Two of the three compounds not effective against VESV in a 20-min exposure at 4 and 25 degrees C were also effective at 37 degrees C. The test iodophor compound inactivated SMSV completely but had only minimal inactivating activity against VESV at the three temperatures tested.
Little is known about the occurrence of antimicrobial resistance determinants in staphylococci isolated from food and food processing industries. Quaternary ammonium compound (QAC)-resistant coagulase-negative staphylococci (CNS) isolated from food and food-processing industries were investigated for the presence of genetic determinants (qacA/B and qacC/smr) encoding resistance to the QAC benzalkonium chloride (BC), several antibiotic resistance genes, and staphylococcal insertion sequences IS257 and IS256. Six qacA/B-harboring strains were resistant to penicillin and hybridized to a blaZ probe. The qacA/B and blaZ probes hybridized to plasmids of similar size in three isolates. Molecular and genetic characterization of the 23-kb plasmid (pST6) of Staphylococcus epidermidis St.6 revealed the presence of qacB adjacent to an incomplete beta-lactamase transposon Tn552 encoding the gene cluster blaZ, blaR, and blaI. Sequence analysis of flanking regions and the intergenic region between blaZ and qacB revealed the presence of IS257 downstream of blaZ as well as sin and binR between blaZ and qacB. In the three other BC and penicillin-resistant strains, the qacA/B and blaZ genes were located on separate plasmids. A qacC harboring S. epidermidis strain (St.17) also hybridized to tetK (tetracycline resistance) and ermB (erythromycin resistance) genes. The individual genes were located on separate plasmids, suggesting no linkage between QAC and antibiotic resistance determinants. Plasmid-free Staphylococcus aureus RN4220 allowed uptake of the pST6 plasmid DNA, indicating that the resistance genes could potentially be transferred to pathogens under selective stress. In conclusion, presence of both resistance determinants could lead to co-selection during antimicrobial therapy or disinfection in hospitals or in food industries.
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Two novel analytical methodologies using capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) were developed and compared for the determination of benzyldimethyldodecylammonium bromide (BAB) in commercial compound chemical disinfectants. The LC analysis was performed with a Kromasil C18 (200 mm x 4.6 mm, 5 microm) column and a mobile phase of A:B = 80:20 (A: acetonitrile, B: 4 mmol/L octanesulfonic sodium--0.02 mol/L acetic sodium, adjusted with acetic acid to pH 5.2) at a flow rate of 1.0 mL/min. Detection was by ultraviolet absorption at 262 nm. The CE analysis was performed in a bare fused-silica capillary with 75 microm i.d. and total length of 46.4 cm with a buffer solution of 50% acetonitrile -50 mmol/L NaH2PO4, pH 2.24. The applied voltage was 20 kV. Detection was by ultraviolet absorption at 214 nm. Under optimized conditions, the HPLC retention time and CE migration time for BAB was 9.18 and 5.08 min, respectively. Calibration curves of peak area versus concentration gave correlation coefficients of 0.9996 for HPLC and 0.9994 for CE. The detection limits for HPLC and CE were 1.6 mg/L and 0.2 mg/L, respectively. Average recoveries at three concentration levels (50, 100, 200 mg/L for HPLC: 20, 40, 100 mg/L for CE) were 99.94 +/- 1.5, 99.64 +/- 1.3 and 99.61 +/- 0.4% for HPLC and 120.47 +/- 2.6, 102.06 +/- 8.7 and 103.05 +/- 3.0% for CE, respectively. Although both methods were shown to be suitable for the determination of BAB in commercial disinfectant compounds, CE provided analysis with less solvent purchase/disposal and better column efficiency, whereas HPLC provided superior precision.
The micellization as well as the interaction with model membranes of dodecyltrimethylammonium halides (DTAX) and N-dodecyl-N,N-dimethyl-N-benzylammonium halides (DBeAX) were studied at 298K and 313K by means of titration calorimetry. The calorimetric curves reflect both the counterion and benzyl group effects on the interaction of the surfactants studied with the lipid bilayer. Bromide as counterion enhanced the interactions more than chloride of both DTAX and DBeAX compounds with model membranes. Further, we studied the influence of DTAX and DBeAX on calcium ion desorption from the liposome membrane using a radioactive tracer method. DBeAX proved more efficient in desorption of calcium than DTAX. Iodides of these compounds enhanced this process more than bromides and chlorides.
Antibacterial effect of 17 ammonium compounds of the type of N,N'-bis(alkyldimethyl)-alpha, omega-alkanediammonium dibromides was tested on anaerobically sporulating bacteria of the genus Clostridium. A sizable antibacterial activity was displayed by five N,N'-bis(alkyldimethyl)-1,6-hexanediammonium dibromides and by four N,N'-bis(decyldimethyl)-alpha, omega-alkanediammonium dibromides. These compounds exhibited activity higher than, or comparable with, that of the reference standards Ajatin and Septonex. The maximum antibacterial activity was found in compounds whose alkyl chain contained 9-12 carbon atoms. Compounds with a lower number of carbon atoms in the chain (less than 8) exhibited a low activity.
Thirty patients (60 eyes) with bilateral open angle glaucoma in whom normalization of the IOP could not be obtained by a conservatory treatment with miotics are presented. In the period of 3 months they were given twice daily a 0.5% solution of Vistagan-Liquifilm, a compound blocking as well the beta 1 as the beta 2 receptors. After 2 weeks 76.7 p.c. of the treated eyes showed a normalization of the intraocular pressure and 23.3 p.c. an improvement. After 3 months the IOP was normalized in 73.3 p.c.; an improvement showed 26.7 p.c. of the eyes. The compound was well tolerated and did not cause any complications from the side of the respiratory or circulatory system.
S-alkylthiuroniumhalides according to formula I (table 1) have been tested under standardized conditions with respect to their antimicrobial activity against bacteria, yeasts and fungi. In table 2 the bacteriostatic and fungistatic efficiency and in table 3 the microbicidal efficiency of 8 different S-alkylthiuronium compounds are compared with the efficiency of N,N-dimethyl-coconutoilalkyl-benzyl-ammonium-chloride. The germ inhibitory effect of the quaternary ammonium compound has been superior to the S-alkylthiuronium salts in almost all respects. The germicidal effect of the S-alkylthiuroniumhalides depends on the alkyl chain length bound to the S-atom and gets the optimum with S-dodecylthiuronium-chloride. Already a 0.0005% concentration is sufficient to kill all test germs within 30 minutes. S-dodecylthiuroniumchloride proved to be just as effective as the known well effective quaternary ammonium compounds. It seems to be possible to increase the microbicidal efficiency by additional alkylating - specially methylating - of both nitrogen atoms.
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For the study of the virucidal activity of a disinfectant by the gel filtration or the dilution methods, the concentration of virus has to be high enough to determine a decrease in titer of at least 4 logarithm units. A filtration technique for rapid separation of the disinfectant and the virus is described that overcome this limitation. The method is applicable to any chemical compound and gives results equivalent to those of the techniques required by the French norms (NF T 72-180).
The antibacterial activities of a homologous series (C8-C18) of alkylbenzyldimethylammonium cholorides (ABDAC) against Pseudomonas aeruginosa have been measured using both a minimum inhibitory concentration (MIC) procedure and a sterilization kinetics test carried out in deionized water. There was a log-linear relationship between activity measured by kinetics and carbon number. With MIC there was a log-linear relationship up to C14, when there was a turndown in activity. Consideration of the colloidal association of ABDAC in deionized water and in a simple salts growth media leads us to suggest that use of high concentrations of nutrient salts in MIC tests will lower the effective concentration of the surface active agents. This change may be responsible for the turndown in activity observed in MIC tests, and that in such circumstances the MIC test does not give a true reflection of the intrinsic activity of the compounds. Literature reports of parabolic relationships between ABDAC alkyl chain length and antimicrobial activity are reinterpreted on this basis.
The in vitro spermicidal activity of the commonly used surfactant spermicides and the antiseptic chlorhexidine, were quantified in a statistically reproducible manner, using donor semen and image capture analysis. The spermicidal activity was expressed as the ED50 under defined assay conditions. Using these parameters, the order of spermicidal activity was: Menfegol > nonoxynol-9 approximately benzalkonium chloride > sodium docusate > chlorhexidine. These differences were statistically significant.
Rat peritoneal mast cells were exposed to the neurohormone and basic opioid peptide beta-endorphin. beta-Endorphin induced a dose-dependent release of histamine from the mast cells. A significant histamine release was found at 5 mumol/l of beta-endorphin and maximal release (35% of total) at 20 mumol/l. The histamine release process was very rapid and terminated within 30 s at 37 C, and in this sense is very similar to the histamine release induced by compound 48/80 or neurotensin. The histamine release was temperature-dependent showing an optimum release around 30 C, and it was independent of available extracellular calcium, but was inhibited in the presence of high extracellular calcium concentrations. Naloxone, only in very high concentrations (10 mmol/l), inhibited the release, and the very same concentration also inhibited the neurotensin - as well as the compound 48/80-induced histamine release. Cromoglycate and benzalkoniumchloride, a 48/80 antagonist, both produced a progressive dose-dependent inhibition of beta-endorphin-, neurotensin- as well as compound 48/80-induced histamine release. Taken together, the findings indicate that the opioid peptide beta-endorphin induces a selective, energy-dependent release of histamine from peritoneal rat mast cells. The pattern of release has much in common with that of compound 48/80 and other basic peptides, such as neurotensin and substance P. In addition this pattern of release is similar to that induced by dynorphin.
Surface disinfection studies mimicking worst-case scenarios in badly cleaned poultry houses were made with 3 bacterial isolates (Salmonella enteritidis, Salmonella senftenberg, and Enterococcus faecalis), and 3 1% disinfectant solutions, formaldehyde (F; 24.5% vol/vol), glutaraldehyde/benzalkonium chloride (G; Bio Komplet Plus), and a peroxygen compound (P; Virkon S), with World Health Organization (WHO) standard hard water as a control. Materials (concrete paving stones, steel feed chain links, wooden dowels, and jute egg belts) and organic matter found commonly in poultry houses (feed, fats, egg yolk) were used in the tests. Organic matter inoculated with high numbers of stationary phase cultures was added to materials and dried for 24 h at different temperatures (6, 11, 20, or 30 degrees C), immersed in solutions for set time periods (5, 15, or 30 min), and dried again for 25 h (6, 11, or 30 degrees C). Then, traditional recovery procedures (using 10-fold dilutions until 10(-4), i.e., a most probable number method) were applied. For the 2 Salmonella isolates, the efficacy of the solutions was (in decreasing order): formaldehyde > glutaraldehyde/benzalkonium chloride > peroxygen compound > WHO hard water, except when feed chain links with fats were disinfected using 30 degrees C before and after disinfection, for which the peroxygen compound seemed more effective. Enterococcus faecalis was equally or less susceptible than S. enteritidis and S. senftenberg, indicating its suitability as an indicator bacterium. For the peroxygen compound, S. senftenberg was more susceptible than S. enteritidis in spite of higher minimum inhibitory concentrations to this disinfectant for the former.
The use of flow cytometry to rapidly assess the viability of Pseudomonas spp. and Staphylococcus spp. after exposure to a quaternary ammonium compound (QAC) was investigated using rhodamine 123 (Rh 123), Stain A (LIVE Stain) accumulating in viable but not in dead cells (Live/Dead Baclight bacterial viability kit, Molecular Probes Inc., Eugene, OR, USA), and Sytox green (Molecular Probes) accumulating in dead but not viable cells. Staining conditions were optimized for each stain. The fraction of viable cells after exposure to benzalkonium chloride was determined by using the three staining techniques and colony counts on agar medium. For all Staphylococcus spp. tested there was a high correlation the methods based on flow cytometry and colony counts irrespective of which stain was used. Although viable, all Pseudomonas spp. tested accumulated Rh 123 poorly and about 30% failed to accumulate LIVE stain as well. However, the correlation between colony counts and Sytox green labelling of Pseudomonas spp. was high. Our results indicate that flow cytometry together with live or dead cell labelling can be used to study the bactericidal effect of QACs. The methods based on LIVE stain and Sytox green were simpler and less time consuming than Rh 123 labelling. Only Sytox green could be used with all strains of Staphylococcus and Pseudomonas tested.