Method and apparatus for testing microbial interaction with growth affecting substances

A apparatus and method for calculating the expansion interacting chemical potency and expansion ratio for the intersections of a scanning spot using a track of observable microbial colonies on an interaction plate. The potency is a measure of the burden of a growth interacting substance which is deposited on the interaction plate each unit volume of the expansion culture medium. The growth ratio is a measure of this growth interacting chemical effect on growth of colonies of microbes on the interaction plate across the path of interaction of the scanning area with visible microbial colonies.


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1. Field of the Invention

The invention relates to techniques for measuring the impact of growth interacting substances on microbial growth.

2. Description of the Prior Art

One well known test is that the place diffusion test where a solution of an expansion interacting chemical is applied to a culture medium that has been inoculated using germs. The resultant plate is incubated for a time period sufficient toproduce visible microbial colonies for areas of the plate where the effectiveness of the expansion interacting substance was not high enough to inhibit expansion. The place test has proven deficiencies. First, it does not provide direct quantitive identification ofthe effectiveness of the expansion interacting material points of interest on the incubated plate such as the point of inhibition. Second it’s restricted by the degree of diffusibility of expansion interacting materials to the parasitic culture medium.

A second well-known testing method of expansion interacting materials involves the creating of a collection of options of increasing dilution of the growth interacting chemical. Each solution is employed into a microbial culturing medium that has beeninoculated using a microbe solution and simmer for a time adequate to detect the effect of the solution on bacterial growth. This method also suffers from recognized drawbacks. In the first place, it takes time consuming manual dilutions and requiresthe use of a large number of culture networking boxes. It also does not easily yield exact quantitative data on the effectiveness of the expansion interacting substance being analyzed. In the case of its use to discover the point of inhibition, it usuallyreveals only a variety of potency between which growth inhibition occurs.

The area as well as the dilution tests both suffer from the drawback of not easily facilitating testing of development interacting substances to determine their consequences in potencies that are significantly less than those that completely inhibit microbe development.

The dilution method is also used to find out the impact of growth interacting substances at less than inhibiting potencies by counting the number of surviving microbial colonies. The disadvantage of this process is that it needs separatetests because exposure times for survivor measurements are generally distinct than exposure times for inhibition measurement.

Each one of the above methods suffer from being time consuming because of the requirement for manual manipulation and because they do not easily yield continuous quantitive information on the potency of an expansion interacting substance for diverse points ofinterest on a growth curve of the microbes being studied.


Spiral Systems, Inc..

Generates an instrument under the signature SPIRAL PLATER for plating onto a parasitic culture moderate a solution containing an unknown concentration of microbes to determine the concentration of microbes at the solutionby counting the resultant colonies after an incubation period. The remedy is deposited on a round culture medium plate within an Archimedes spiral. The alternative decreases in volume per unit length of the coil as the radius of the coil increases.The device is described in U.S. Pat. Nos. 3,799,844, 3,892,632, and 3,962,040. These patents are incorporated herein by reference.

A laser bacteria colony counter (Model 500A) is fabricated by Exotech Incorporated, of Gaithersburg, Md., specifically for counting the colonies which bring about the plating of a microbe containing solution together with the SPIRAL PLATER. The lasercounter is your preferred microbe colony scanning mechanism that’s utilized with the creation. The Model 500A is described in a booklet entitled”User Manual Model 500A Laser Compounds Colony Counter, October 1981″ by Spiral System Instruments, Inc.. ofBethesda, Md., 20814. The description of this Model 500A is incorporated herein by reference.

The Food and Drug Administration pursuant to 21 CFR 036.105 requires that each manufacturer of antibiotics must conduct tests of each batch of freshly manufactured antibiotic to ascertain compliance with effectiveness standards. Implementation of thisrequirement entails the measurement of zones of inhibition of the test substance relative to the magnitude of inhibition zones produced by known potencies of management substances. Measurement of these zones of inhibition is performed either manually or by vidiconscanners. These tests are expensive in their need for extensive time, materials, and equipment.

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