PubMed · 5269100
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F Custer, T Coyle. Instrument changes during sterilization.. https://doi.org/10.1177/00220345700490030401
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A conductivity assay that represents a new biotest able to detect the effects of membrane-toxic compounds, e.g., detergents, organic solvents, and radical formers, on various organisms was previously described and developed. The conductivity assay measures ion leakage from cells, tissues, or whole plant and animal organisms whose membrane systems have been damaged by membrane-toxic compounds. In this study the specificity of the conductivity assay for membrane-toxic compounds was tested by comparing the electrolyte efflux from Elodea canadensis leaves during incubation with a well-known detergent (benzalkonium chloride) using different plant physiological and biochemical techniques (photochemical efficiency, plasmolysis capacity, NBT reduction, and electron microscopy of membranes of E. canadensis leaves). The comparison of the different methods proved that the electrolyte loss during benzalkonium chloride incubation determined in the conductivity assay is due to membrane impairment. The observed electrolyte loss correlated with a reduction of photochemical efficiency and a decrease in both plasmolysis and NBT reduction capacity. Furthermore, a disintegration of the plasmalemma could be seen in the electron micrographs. These results indicate that the measured electrolyte loss in the conductivity assay is a specific effect of membrane-toxic compounds.
The distribution of known genes conferring resistance to quaternary ammonium compounds (QACs) among different species of staphylococci isolated from the food industry was investigated. Twenty-four isolates hosting one of the genes qacA/qacB, smr, qacG or qacH, were subjected to species identification. Species determination was performed by biochemical analyses (API STAPH), comparative 16S rDNA sequence analysis and tDNA intergenic spacer length polymorphism analysis. Good correlation was obtained between the different methods. The isolates belonged to six different species of coagulase-negative Staphylococcus. The most commonly found species were Staphylococcus epidermidis and Staphylococcus saprophyticus. The results also indicated the possible spread of specific isolates of staphylococci which may reflect the dominance of certain strains in environments were QACs are used on a regular basis. The isolates were further characterized by the resistance phenotype to antimicrobial agents including antibiotics and disinfectants. Resistance to ampicillin, penicillin G and dyes was prevalent in strains harbouring the qacA or qacB genes, features also common among clinical staphylococci containing qacA/qacB. One QAC resistant strain harbouring the smr gene showed resistance to ampicillin, penicillin, tetracycline, erythromycin and trimethoprim. No enterotoxin production was detected among the QAC resistant strains.
CONTEXT: In most countries, the use of topical nasal decongestants is limited to a maximum of 10 days because of the risk of developing rebound mucosal swelling and rhinitis medicamentosa. OBJECTIVE: To determine whether topical nasal decongestants can be safely used for 10 days in patients with chronic inflammation of the nasal mucosa. DESIGN: Double-blind, randomized, controlled, parallel study. PATIENTS: Thirty-five patients with vasomotor rhinitis selected from our outpatient department. INTERVENTION: Eighteen patients received oxymetazoline hydrochloride (0.5 mg/mL) nasal spray containing the preservative benzalkonium chloride (0.1 mg/mL), and the other 17 were treated with oxymetazoline nasal spray without benzalkonium chloride. Before and after the treatment, recordings of the nasal mucosa and minimal cross-sectional area were made with rhinostereometry and acoustic rhinometry, followed by histamine hydrochloride challenge tests. Symptoms of nasal stuffiness were estimated on visual analog scales (0-100) in the morning and the evening, just before the nasal spray was used. RESULTS: No rebound swelling was found after the 10-day treatment in the 2 groups with either of the methods or as estimated by symptom scores. In the group receiving oxymetazoline containing benzalkonium chloride, but not in the other group, the histamine sensitivity was significantly reduced after treatment (P<.001). CONCLUSIONS: It is safe to use topical nasal oxymetazoline with or without benzalkonium chloride for 10 days in patients with vasomotor rhinitis. However, this study indicates that benzalkonium chloride in nasal decongestant sprays affects the nasal mucosa also after short-term use.