BS 6905-1987. Method for estimation of concentration of disinfectants used in dirty conditions in hospitals by the Kelsey-Sykes test modified.

Test not accredited in our laboratory.

      Capacity tests of disinfectants, whose prototype is the Kelsey-Sykes test, provide information on the ability of a disinfectant solution to be exposed to microorganisms and organic matter without losing its activity. These studies can use concentrations recommended for a disinfectant and an application, and the intervals in which the containers must be renewed with disinfectants where contaminated items that may contain microorganisms and organic matter deposited. To perform this test, the manufacturer must inform the laboratory conditions in which the disinfectant will be used, and the laboratory must choose the desired test microorganisms in conducting the test. The most recommended microorganisms for testing are Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Proteus spp., Candida albicans, ..., but other can be selected. In the test disinfectant solution at the concentration given by the manufacturer, containing organic matter, it is inoculated with a homogenous suspension of one of the microorganisms selected and maintained at the temperature chosen by the manufacturer (normally +22ºC). At 10 minute intervals, over one hour, the bacterial suspension is added, taking a sample of the mixture at 8 minutes of inoculation to determine the presence of viable microorganisms by both plating medium culture, as by inoculation in liquid culture media. The procedure is performed for one hour, so 6 inoculations can be performed with the bacterial suspension. This procedure must be performed for each of the microorganisms chosen. The endpoint of the test, with respect to the activity of the disinfectant, is the largest number of additions of the bacterial suspension, whose counts provide less than 5 colonies in five samples, or less than 2 positive cultures in liquid medium. Generally, a dilution of use of a disinfectant is considered satisfactory if they can make three or more inoculations before a positive culture obtained. In the test, three concentrations of disinfectant, one chosen by the manufacturer, and two, upper and lower respectively, selected by the laboratory conducting the test, which are used as controls are used. In the test neutralizers are used before performing cultures to inactivate the disinfectant before performing feasibility cultures, so the manufacturer must provide the components of the disinfectant so you can choose the most appropriate neutralizer. For testing, three test microorganisms in one concentration of disinfectant, an interfering substance, and a temperature exposure, are chosen by the manufacturer.