RESUMEN
AIMS: Electrochemically activated solutions (ECAS) are generated from halide salt solutions via specially designed electrolytic cells. The active solutions are known to possess high biocidal activity against a wide range of target microbial species, however, literature revealing the kill-kinetics of these solutions is limited. The aim of the study was to identify the kill-rate and extent of population kill for a range of target species (including endospores) using ECAS generated at the anode (anolyte). METHODS AND RESULTS: Standard suspensions of methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus atrophaeus spores and Clostridium difficile spores were treated with anolyte in a quantitative suspension assay. For vegetative cells, all concentrations of anolyte tested reduced the viable population to below the detection limit within 10 s. At a concentration of 99%, anolyte produced a log(10) reduction factor of greater than five in viable B. atrophaeus endospores within 90 s and reduced numbers of C. difficile endospores to below the experimental detection limit within 20 s at concentrations of 5% or greater. CONCLUSIONS: Anolyte was highly effective in killing test-bacteria and spores. The bactericidal efficacy was retained against vegetative cells at dilutions as low as 1% and against C. difficile spores as low as 5%. SIGNIFICANCE AND IMPACT OF STUDY: The results of this study demonstrate that ECAS are effective at lower concentrations and act more rapidly than previously reported. Potent bactericidal and sporicidal activity coupled with point-of-use generation, low production-costs and environmental compatibility suggest that acidic ECAS has the potential to be a useful addition to the current armoury of disinfectants.
Asunto(s)
Antibacterianos/farmacología , Bacterias/efectos de los fármacos , Desinfectantes/farmacología , Oxidantes/farmacología , Esporas Bacterianas/efectos de los fármacos , Bacillus/efectos de los fármacos , Bacillus/crecimiento & desarrollo , Bacterias/crecimiento & desarrollo , Clostridioides difficile/efectos de los fármacos , Clostridioides difficile/crecimiento & desarrollo , Recuento de Colonia Microbiana , Electrodos , Electrólisis , Límite de Detección , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Oxidación-Reducción , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/crecimiento & desarrollo , SolucionesRESUMEN
A clinical isolate of Streptococcus pneumoniae was transformed with a plasmid containing the lux operon of Photorhabdus luminescens that had been modified to function in gram-positive bacteria. Cells containing this plasmid produced light stably and constitutively, without compromising the growth rate. Light output was correlated with measurements of optical density and viable counts during exponential growth and provided a sensitive, real-time measure of the pharmacodynamics of the fluoroquinolone gemifloxacin.
Asunto(s)
Antiinfecciosos/farmacología , Fluoroquinolonas , Genes Bacterianos/fisiología , Naftiridinas/farmacología , Streptococcus pneumoniae/efectos de los fármacos , División Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Gemifloxacina , Expresión Génica/efectos de los fármacos , Humanos , Mediciones Luminiscentes , Pruebas de Sensibilidad Microbiana , Operón/genética , Plásmidos/genética , Streptococcus pneumoniae/metabolismoRESUMEN
Heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) may account for treatment failure with vancomycin and act as a precursor of vancomycin-intermediate or -resistant S. aureus. The activity of vancomycin was assessed against vancomycinsusceptible, hVISA and VISA strains in a dilutional pharmacokinetic model. Over a 48 h period, total bacteria and cells with a vancomycin-intermediate phenotype were quantified. Total counts of hVISA were reduced by vancomycin in a similar way to a vancomycin-susceptible control. The vancomycin-intermediate sub-population was eradicated from the model within one dose interval. Exposure to low vancomycin concentrations did not result in an increase in the proportion of cells which were vancomycin intermediate. Short-term exposure of hVISA to vancomycin at gradient concentrations did not increase the proportion of cells with vancomycin-intermediate phenotype.
Asunto(s)
Antibacterianos/farmacocinética , Resistencia a la Meticilina , Staphylococcus aureus/efectos de los fármacos , Vancomicina/farmacocinética , Antibacterianos/farmacología , Recuento de Colonia Microbiana/métodos , Humanos , Resistencia a la Meticilina/genética , Pruebas de Sensibilidad Microbiana , Vancomicina/farmacologíaRESUMEN
A simple in vitro model for culture of biofilm populations of self-bioluminescent Pseudomonas aeruginosa was used for real-time monitoring of the effects of ciprofloxacin. Biofilms of these organisms were established within Sorbarod filters, perfused with a chemically defined simple salts medium. The biofilm population was shown to achieve a pseudo-steady state which was reproducible and stable over several days. The viability of membrane-associated and eluted cells was assessed by spread plate viable counts and by monitoring bioluminescence as a measure of metabolic activity. Pseudo-steady state biofilms were exposed to 5x MIC ciprofloxacin (0.3 mg x l(-1)) in the perfusing medium for 1 h. Whilst both methods for viability assessment indicated an immediate reduction in viable cell numbers, the decline recorded with bioluminescence was greater. The use of bioluminescent bacteria proved to be a rapid and sensitive method for the measurement of real-time antibacterial effects on a bacterial biofilm.
Asunto(s)
Antiinfecciosos/farmacología , Biopelículas/efectos de los fármacos , Ciprofloxacina/farmacología , Mediciones Luminiscentes , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/fisiología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Biopelículas/crecimiento & desarrollo , Medios de Cultivo , Pruebas de Sensibilidad Microbiana/métodos , Pseudomonas aeruginosa/genéticaRESUMEN
Escherichia coli isolate 16,906 expressing lux genes was used for real-time monitoring of moxifloxacin effects on bacterial metabolism compared with effects on cell replication. Viable counts showed concentration-dependent killing by moxifloxacin; real-time measurement of bioluminescence on the same cultures showed metabolic activity over 54 h, but with greater inhibition at 1 x MIC than with higher MIC multiples. Post-antibiotic effect was longer when determined using bioluminescence than by viable counts. The control-related effective regrowth time was consistent with both methods. Bioluminescent bacteria provide a rapid and sensitive means for measuring antimicrobial effects on bacterial metabolism.