title: [Use of impedance test for testing effectiveness of drug preservatives].
abstract: Pharmacopoeias contain preservation efficacy test for estimating antimicrobial activity of chemical compounds added to pharmaceutical preparations in multidose containers in order to inhibit bioburden growth. This method involves the treating of preserved products with bacteria and yeast cells and monitoring the survival of microorganisms through the specified time periods up to 28 days. The last stage of assay--incubation and colony counting--is very time consuming. Recent advance in technology enables faster and more convenient detection in comparison to traditional methods. Impedance method is based on the principle that conductance and capacitance of cultivation medium increases when bacteria grow and metabolize, Impedance time detection is inversely proportional to initial bacterial population. Six different products were utilised throughout the study. The calibration curves were calculated for each of the tested strains by comparison between standard plate count method and detection time measured in Bactometer system. In our study log reduction calculated in alternative method were similar to those obtained in plate count assay. All of the tested preparations, except one, exhibited acceptable activity against bacteria and fungi and meet the pharmacopoeal requirements. The studies indicated a positive correlation between standard plate count results and impedance reading. The procedure with the usage of Bactometer, provides a rapid and accurate system for the determination of bacterial content.
authors.affiliation: Zakład Antybiotyków i Mikrobiologii Narodowego Instytutu Zdrowia Publicznego w Warszawie.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Zareba
authors.forename: Stefan
authors.initials: S
authors.lastname: Tyski
mesh_terms: D002138:Calibration; D015169:Colony Count, Microbial / Q000379:methods; D004340:Drug Contamination / Q000517:prevention & control*; D017097:Electric Impedance; D011310:Preservatives, Pharmaceutical / Q000494:pharmacology / Q000592:standards
chemical_list: D011310:Preservatives, Pharmaceutical