Chemistry: molecular biology and microbiology – Apparatus
Patent
1995-02-09
1997-05-13
Beisner, William H.
Chemistry: molecular biology and microbiology
Apparatus
4352864, 4353091, 422100, C12M 126
Patent
active
056292015
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for applying a liquid sample onto a culture medium with a prescribed quantity and distribution, comprising a syringe, a movable nozzle connected to the syringe through a line, a table for a culture medium container, a container for sample liquid, a container for desinfectant, and a control system and movement mechanism for displacing the nozzle.
In a prior art apparatuses of this type, for example, U.S. Pat. Nos. 3,799,844; 3,892,632 and 3,962,040, the sample liquid is applied in a spiral shape onto a so-called agar culture medium. The agar culture medium is applied to the culture medium container, such as a Petri dish, as uniformly as possible and with a prescribed thickness. However, in practice this thickness varies several millimeters. As a result thereof the accurate angular positioning of the nozzle resting on the culture medium is complicated.
Furthermore, problems may arise in the prior art apparatus because the manual desinfection of the line and the nozzle are not carried out properly, which may cause cross-infections of samples.
SUMMARY OF THE INVENTION
The object of the invention is to provide an apparatus, in which the disadvantages as described are removed in an effective way.
According to a first aspect the apparatus according to the invention is characterized by means for automatically ensuring the nozzle of the line to be submerged deeper into the desinfectant than into the sample liquid by means of the movement mechanism.
In this way, a full cleaning operation of the nozzle is ensured and contamination of samples is prevented in a reliable way. In an advantageous embodiment and for this purpose said means comprises an automatic supply of desinfectant from a reservoir to the container thereof for maintaining a minimum level therein, and preferebly the nozzle is reciprocable up and down by means of a movement mechanism for moving it into and out of the desinfectant.
A further measurement for preventing samples in the apparatus to be infected or contaminated is that, in which the volume of the line and nozzle up to the syringe is larger than the volume of the sample liquid, which can maximally be applied. Due to this measure it is impossible for the sample liquid to arrive in the syringe itself when it is sucked in by means of the syringe, in which desinfection is more difficult than within the line. Consequently the risk of infections is substantially reduced in this manner.
According to a second aspect the invention provides an apparatus for applying a liquid sample onto a culture medium in a spiral shape, e.g. for determining the bacteria concentration therein, comprising a line having an inclined nozzle for applying the liquid sample onto the culture medium, a turntable for supporting a culture medium container, wherein the line is supported by a linearly movable slide, characterized by automatic means for adjusting the nozzle and the turntable relative to each other depending on the thickness of the culture medium by means of a sensor.
The invention will hereafter be elucidated with reference to the drawings very schematically showing the embodiments of the apparatus according to the invention by way of example.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic front view of the examplary embodiments of the apparatus according to the invention.
FIG. 2 is a side view of the apparatus of FIG. 1.
FIGS. 3-6 show on an enlarged scale a detached detail of the apparatus of FIGS. 1 and 2, in different positions.
FIGS. 7 and 8 show diagrams of two embodiments of the liquid reception and delivery system according to the invention.
FIG. 9 shows on an enlarged scale and in cross section detail IX in FIG. 3.
FIG. 10 shows on an enlarged scale and in cross section detail X in FIG. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The drawings show an apparatus for applying a liquid sample onto a culture medium 1 in a prescribed quantity and distribution, for example for determining the bacteria concentration
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Aurik Erik A.
Nugteren Robert J.
Rodenburgh Arie H.
Beisner William H.
Priolion Development B.V.
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