US 3830702 A
Description (OCR text may contain errors)
20, 174 o. A. BECKFORD 3,830,702
BACTERIOLOGICAL MEDIA TUBE Filed Feb. 2. 1973 United States Patent 3,830,702 BACTERIOLOGICAL MEDIA TUBE Orville A. Beckford, Port Washington, N.Y., assignor to Diagnostic Research, Inc., Roslyn, N.Y. Filed Feb. 2, 1973, Ser. No. 329,014 Int. Cl. C12k 1/10 U.S. Cl. 195-139 3 Claims ABSTRACT OF THE DISCLOSURE A transparent test tube is provided with a constriction which permits the tube to be filled with two unlike media separated by a gas bubble. The constriction is provided with an arcuate shape 'which permits filling of the lower portion of the escape confined gas with a constriction small enough to limit the flow from the upper portion to the lower portion during the filling operation.
This invention relates to transparent tubes containing bacteriological media.
BACKGROUND OF THE INVENTION It is known to employ tubes containing media for providing biochemical reactions for the purpose of identifying various species of bacteria. For example, test for phenylalanine deaminese, H 8 production, indole, lysine decarboxylation, ornithine decarboxylation, motility, lactose fermentation and glucose fermentation are combined in such a manner that in the presence of individual species of enterobacteriaceae the media takes on a particular characteristic appearance.
It has been found that by putting a constriction in the tube between media designed for aerobic and anerobic bacteria, clearer, sharper colors and improved shelf life is obtained. However, the size and shape of the constrictions have been found to be critical during the filling operation. For example, if the opening is too large, the upper layers of media will mix with the lower layer and not provide for isolation. If too small, air tends to be trapped in the lower media causing bubbles to form as the media cools from the warm state, which it is initially introduced in, to the gel state. Accordingly, it is an object of this invention to provide an improved constricted tube.
SUMMARY OF THE INVENTION A transparent test tube is provided with a constricted orifice having an arcuate shape which, in cross section, resembles a pair of opposed hyperbolas. The tube is filled with two different test media separated by a gas bubble in the orifice area.
DESCRIPTION OF THE DMWINGS In the various figures of the drawing like parts designate like figures of the drawing.
In the drawing:
FIG. 1 is a view taken in elevation of a media tube;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a sectional view taken along line 4-4 of FIG. 2; and
FIG. 5 is a view taken in elevation of the tube of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, in FIG. 1 there is shown a transparent test tube which may be made of glass or 3,830,702 Patented Aug. 20, 1974 suitable plastic which is provided with a constricted area 12. The constriction provides an opening 14 (FIG. 2') and as is shown in FIG. 4, is defined by two arcuate portions 15 and 16 which resemble hyperbolas, although they need not mathematically follow the hyperbola equation and may be, for example, elliptical. Other arcuate shapes may be employed.
Dimension a is typically 2 mm.:0.4 mm., while dimension b is typically 1 mm. The overall length of the arcuate portion should be about 4 mm. The completed tube is shown in FIG. 5. Tube 10 is provided with media 18 and 20 and is provided with a closure member 22. The closure member may be a stopper or a tight fitting plastic cap 22 as shown in FIG. 5.
Typically, media in a liquid state would be injected into the lower portion by means of a needle extending through opening 14. It has been found that with the arcuate shape, trapped air is readily forced past the needle into the atmosphere. After the lower portion is filled, the upper portion is filled with media in liquid form. The media is usually an agar based composition containing test media. When heated the agar media is quite fluid and is readily introduced into the tube. On the other hand, upon cooling the agar media congeals.
One application of the tube is disclosed in applicants copending application filed concurrently entitled Enteric Bascilli Differential Apparatus, Ser. No. 329,176.
Various other configurations and dimensions for the constricted portion were tested and found to be characterized by a high reject rate. One cause for rejection was the formation of bubbles which were captured by the gelling media. With the introduction of the present configuration, rejections for this reason have become nil.
These and other objects, features and advantages of the invention will, in part, be pointed out with particularity and will, in part, become obvious from the following more detailed description of the invention taken in conjunction with the accompanying drawing which forms an integral part thereof.
What I claim as new and desire to secure by Letters Patent is:
1. A bacterial medium tube comprising:
(a) an elongated transparent tube having a lower compartment of a first cross-sectional area and an upper compartment of substantially the same cross-sectional area and a conduit extending from the said upper to the said lower chamber, said conduit being defined by walls continuously tapering inwardly from each of said chambers defining an orifice having a traverse dimension between 1.6 mm. and 2.4 mm.
(b) a first medium in said lower compartment;
(c) a second medium in said upper compartment different than that of said first medium;
(d) a gas in said conduit separating said first and said second medium.
2. The tube of Claim 1 formed of glass.
3. The tube of Claim 1 formed of plastic.
References Cited UNITED STATES PATENTS 3,750,645 8/1973 Bennett et al. 23-292 X A. LOUIS MONACELL, Primary Examiner R. J. WARDEN, Assistant Examiner U.S. Cl. X.R. l54, 103.5 R