GB1563088A

GB1563088A - Template for measuring inhibition of microorganism gorwth

Info

Publication number: GB1563088A
Application number: GB2248275A
Authority: GB
Original assignee: Scientific Hospital Supplies Ltd
Current assignee: Scientific Hospital Supplies UK Ltd
Priority date: 1976-08-20
Filing date: 1976-08-20
Publication date: 1980-03-19

Description

(54) TEMPLATE FOR MEASURING INHIBITION OF MICROORGANISM GROWTH (71) We, SCIENTIFIC HOSPITAL SUPPLIES LIMITED, a British Company, of 38 Queensland Street, Liverpool L7 3JG, Merseyside, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a template for use in connection with test devices used in micro-biological laboratories to test the anti-microbial activity of anti-microbial substances. Such test devices normally comprise one or more anti-microbial substances carried by a carrier member, which may be of a material such as paper. The anti-microbial substances are preferably impregnated into the carrier member.

The micro-organism against which the anti-microbial substance is to be tested is normally spread on to the surface of an agar medium supported on a suitable surface, e.g.

the inside surface of a petri dish and the test device including one or more anti-microbial agents is placed on the surface of the medium. After a period of time an inhibition zone will be observed in the area of any of the anti-microbial agents to which the microorganism is sensitive. The size of the zone compared with the size of inhibition zone using a standard micro-organism is a measure of the activity of the anti-microbial agent against the micro-organism.

According to the present invention there is provided a template for use in connection with a micro-biological test device comprising a planar support and outwardly extending radial projections said projections being in the same plane as the support, which template comprises a support having a plurality of references marked thereon for registering with corresponding markings on, or contours of, said test device, coupled with sets of calibration marks thereon arranged to correspond in use respectively with portions of the areas surrounding the projections, there being a set of calibration marks for each area and the sets of calibration marks extending radially on the support.

The support of the test device may be in the form of a ring or disc with each of the projections having an anti-microbial agent carried thereby.

In one preferred embodiment of the present invention the sets of calibration marks comprise a pluarity of spaced concentric rings thereon intersected by radial lines, the rings being arranged to correspond in use with at least the area surrounding the projections.

In another preferred embodiment of the present invention the sets of calibration marks comprise a pluarity of giaduated scales radially disposed on the support, the number and radial position of said scales corresponding to the number and radial position of the projections on the test device (usually 6 or 8 projections equally spaced around the circumference of a circle).

Preferably in this embodiment graduated scales also connect each point which in use will correspond with the centre of that area of projection carrying the anti-microbial agent with the points which in use will correspond with the centres of the two adjacent such areas.

In use the template is placed above or beneath (preferably beneath) the test device in a position such that the device can be viewed and the size of the inhibition zone measured by reference to the calibrations.

The template is preferably made from transparent material.

Preferred materials from which the template may be made include plastics materials, e.g. rigid acetate or polystyrene.

The calibrations are preferably marked on the template by black heat sealed printing.

In use the template is preferably placed beneath the petri dish or other support on which the test is carried out but the template may also comprise the cover of a vessel (e.g. a petri dish) in which the test is carried out. In this event the material which the template is made from should have sufficient strength and rigidity and preferred materials are rigid acetate or polystyrene.

The invention will now be further described by way of example with reference to the drawings accompanying the provisional specification, in which: Fig. 1 is a plan view of a test device, Fig. 2 is a plan view of one form of template in accordance with the present invention which may be used in conjunction with the test device as shown in Fig. 1, and Fig. 3 is a plan view of another form of template in accordance with the present invention and which may be used in conjunction with the test device as shown in Fig. 1.

Referring to Fig. 1 of the drawings there is shown one form of test device with which the template of the present invention may be used. This test device comprises a ring 10 having eight projections 12 attached thereto and extending outwardly therefrom, the roughly circular portion 14 of each projection being impregnated with a different anti-microbial agent. A V-shaped projection 16 extends inwardly from the ring 10 for reference purposes.

The template shown in Fig. 2 comprises a circular disc of transparent plastics material 18 having a series of markings thereon. The markings comprise (a) a circle 20 which corresponds with the outer diameter of the ring 10, (b) a circle 22 corresponding with the inner diameter of ring 10 and having a V-shaped mark 24 extending inwardly therefrom, (c) eight equally spaced radial lines 26, each calibrated with a series of calibrations 28, and (d) eight lines 30 calibrated with a series of calibrations 32, and joining the parts on lines which in use will correspond to the centres of the portions 14.

In use the test device is placed on the organism concerned which in turn is on an agar medium on a suitable support e.g. in a petri dish and the template is either placed above or below the organism and test device, preferably under the petri dish or other support for the agar medium, with the circle 20 in register with the outer diameter of the ring 10, with the V-shaped mark 24 in register with the projection 16, and with each line 26 corresponding with a projection 12. The junction of lines 26 and 30 should correspond with the centres of the circular portions 14. After a period of time the size of any inhibition zone may be measured by reference to the calibrations 32 and a measure of the activity of the particular anti-microbial agent obtained by reference to the size of the inhibition zone using a standard microoranism.

Referring now to Fig. 3 there is shown an alternative construction of template which again may be used in conjunction with the test device of Fig. 1. The template in this instance comprises a disc 34 of transparent plastics material having a plurality of concentric rings thereon and also having eight equally spaced radially extending lines 36.

Rings 38 and 40 correspond with the inner and outer diameters of the ring 10 of the test device, and a V-shaped mark 42 is provided to correspond with projections 16 on the test device. It will be seen that the registering references constitute rings 38 and 40 and mark 42 and the sets of calibration marks are formed by the pluarity of concentric rings intersected by the radial lines 36.

The device of this Figure is used in a similar manner as the device of Figure 2.

It will be appreciated that many variations may be effected to the templates described in the drawings. For example, the templates may be square or any other suitable shape and the calibrations may be arranged in any suitable manner to correspond with the particular test device being utilised e.g. where the test device is similar to that of Figure 1 but includes only six equally spaced projections the templates of Figs. 2 and 3 would be modified to include only six radial lines 26, 36 instead of eight.

WHAT WE CLAIM IS: 1. A template for use in connection with a micro-biological test device comprising a planar support and outwardly extending radial projections, said projections being in the same plane as the support, which template comprises a support having a plurality of references marked thereon for registering with corresponding markings on, or contours of, said test device, coupled with sets of calibration marks thereon arranged to correspond in use respectively with portions of the areas surrounding the projections, there being a set of calibration marks for each area and the sets of calibration marks extending radially on the support.

2. A template as claimed in claim 1, in which said sets of calibration marks comprise a plurality of spaced concentric rings thereon intersected by radial lines, the rings being arranged to correspond in use with at least the area surrounding the projections.

3. A template as claimed in claim, in which said sets of calibration marks comprise a plurality of graduated scales radially disposed on the support, the number and radial position of said scales corresponding to the number and radial position of said projections on the test device.

4. A template as claimed in claim 3, in which graduated scales also connect each

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. which the test is carried out but the template may also comprise the cover of a vessel (e.g. a petri dish) in which the test is carried out. In this event the material which the template is made from should have sufficient strength and rigidity and preferred materials are rigid acetate or polystyrene. The invention will now be further described by way of example with reference to the drawings accompanying the provisional specification, in which: Fig. 1 is a plan view of a test device, Fig. 2 is a plan view of one form of template in accordance with the present invention which may be used in conjunction with the test device as shown in Fig. 1, and Fig. 3 is a plan view of another form of template in accordance with the present invention and which may be used in conjunction with the test device as shown in Fig. 1. Referring to Fig. 1 of the drawings there is shown one form of test device with which the template of the present invention may be used. This test device comprises a ring 10 having eight projections 12 attached thereto and extending outwardly therefrom, the roughly circular portion 14 of each projection being impregnated with a different anti-microbial agent. A V-shaped projection 16 extends inwardly from the ring 10 for reference purposes. The template shown in Fig. 2 comprises a circular disc of transparent plastics material 18 having a series of markings thereon. The markings comprise (a) a circle 20 which corresponds with the outer diameter of the ring 10, (b) a circle 22 corresponding with the inner diameter of ring 10 and having a V-shaped mark 24 extending inwardly therefrom, (c) eight equally spaced radial lines 26, each calibrated with a series of calibrations 28, and (d) eight lines 30 calibrated with a series of calibrations 32, and joining the parts on lines which in use will correspond to the centres of the portions 14. In use the test device is placed on the organism concerned which in turn is on an agar medium on a suitable support e.g. in a petri dish and the template is either placed above or below the organism and test device, preferably under the petri dish or other support for the agar medium, with the circle 20 in register with the outer diameter of the ring 10, with the V-shaped mark 24 in register with the projection 16, and with each line 26 corresponding with a projection 12. The junction of lines 26 and 30 should correspond with the centres of the circular portions 14. After a period of time the size of any inhibition zone may be measured by reference to the calibrations 32 and a measure of the activity of the particular anti-microbial agent obtained by reference to the size of the inhibition zone using a standard microoranism. Referring now to Fig. 3 there is shown an alternative construction of template which again may be used in conjunction with the test device of Fig. 1. The template in this instance comprises a disc 34 of transparent plastics material having a plurality of concentric rings thereon and also having eight equally spaced radially extending lines 36. Rings 38 and 40 correspond with the inner and outer diameters of the ring 10 of the test device, and a V-shaped mark 42 is provided to correspond with projections 16 on the test device. It will be seen that the registering references constitute rings 38 and 40 and mark 42 and the sets of calibration marks are formed by the pluarity of concentric rings intersected by the radial lines 36. The device of this Figure is used in a similar manner as the device of Figure 2. It will be appreciated that many variations may be effected to the templates described in the drawings. For example, the templates may be square or any other suitable shape and the calibrations may be arranged in any suitable manner to correspond with the particular test device being utilised e.g. where the test device is similar to that of Figure 1 but includes only six equally spaced projections the templates of Figs. 2 and 3 would be modified to include only six radial lines 26, 36 instead of eight. WHAT WE CLAIM IS:

1. A template for use in connection with a micro-biological test device comprising a planar support and outwardly extending radial projections, said projections being in the same plane as the support, which template comprises a support having a plurality of references marked thereon for registering with corresponding markings on, or contours of, said test device, coupled with sets of calibration marks thereon arranged to correspond in use respectively with portions of the areas surrounding the projections, there being a set of calibration marks for each area and the sets of calibration marks extending radially on the support.

point which in use will correspond with the centre of that area of a said projection carrying an antimicrobial agent with the points which in use will correspond with the centres of the two adjacent such areas.

5. A template as claimed in any of the preceding claims, which is made from transparent material.

6. A template as claimed in any of the preceding claims, which is made from a plastics material.

7. A template as claimed in claim 6, in which the plastics material is rigid acetate or polystyrene.

8. A template as claimed in any of the preceding claims, in which the calibration marks are marked on the template by black heat sealed printing.

9. A template substantially as hereinbefore described with reference to and as illustrated in Fig. 2 or Fig. 3 of the drawings accompanying the provisional specification.