Analytical instrument for evaluating microbial contamination of an object

摘要

An instrument for ascertaining a viable aerobic microbe count at to employing a two-point calibration curve of tthreshold to TVC for each type of sample. One point on the calibration curve is the x-intercept value (i.e., an estimated or experimental value for the logarithm of the minimum viable aerobic microbe count at commencement of testing (to) in a sample effective for causing the sample to reach tThreshold substantially instantaneously upon commencement of incubation). The other point is ascertained experimentally from a sample having a smaller known viable aerobic microbe count at to.

主权项

1. An analytical instrument comprising an O2 sensor and a microprocessor in electrical communication with the sensor, wherein the instrument is effective for (i) periodically ascertaining an O2 concentration of an incubating sample taken from an object, (ii) determining a time period tThreshold from a time to at which incubation of the sample commenced to a time at which an ascertained O2 concentration for the sample first falls below a threshold value, (iii) correlating tThreshold to a viable aerobic microbe count in the sample prior to incubation, utilizing the linear equation:
y=mx+b  (Eq. 1) wherein: x=logarithm of the viable aerobic microbe count per unit weight of, volume of or area swabbed to obtain a sample at to y=tThreshold x-intercept=(−b/m)=an estimated or experimental value for the logarithm of the minimum viable aerobic microbe count at to in a sample effective for causing the sample to reach tThreshold substantially instantaneously upon commencement of incubation, and m (slope)=(y2−y1)/(x2−x1) wherein:
x1 and y1 are ascertained experimentally by establishing tThreshold for a sample taken from an object having a known x, andx2 and y2 are values of x and y at the x-intercept (−b/m, 0), and (iv) transmitting a correlated value of x to a peripheral device.