Test Methodology
 
Following a 30-60 minute initial incubation at 35C, the CultureStat ampoule is placed in the CultureStat reader and the “Read 1” icon is clicked on the computer.  The reader simultaneously takes a reading of the sample at two different wavelengths of light, measuring respiration and cell mass.  These values are automatically transmitted to the CultureStat software where they are entered and calculated to initial probability for negative or potentially positive (suspect) microbial results. The software permits lab supervisors to select the optimal confidence level for their laboratory.

Following a 2-hour incubation at 35C, the operator conducts “Read 2” in the same manner as Read 1, except the “Read 2” icon is clicked. The CultureStat software records the new readings at the same two wavelengths and compares the Read 2 values to the Read 1 values. The system determines whether the sample contains log phase bacteria based on the value differences for the two wavelengths. If both wavelengths decrease significantly, log phase bacteria are present and the sample is declared positive. A decrease in only one wavelength is usually an indication of lag phase contaminants or below threshold concentrations, and the sample is declared negative. No movement means no growth is occurring, and the sample is declared negative.

The diagram below illustrates the test methodology.  The advantages of the test methodology on patient treatment and care are explained here.