FR2751342A1 - Instrument for taking bacterial or fungal sample from gel culture medium - Google Patents

Abstract

An instrument for taking a sample of bacterial or fungal cells from the surface of a gel culture medium, consists of a thin rod (2 in figure) of metal or plastic, e.g. chrome steel wire or extruded polyethylene between 0.5 and 1 mm thick. The rod is shaped with a holder at one end, and during use its tip is inserted through a colony (3 in figure) of cells of greater diameter than the rod. The rod is pushed down to the bottom of the gel medium as far as the base (5 in figure) of the container in which it is held, and is then withdrawn, leaving its sides coated with the cells.

Description

 The present invention relates to a device and its method of use to collect from bacterial or fungal colonies present on an agar culture medium, a reproducible amount of germs.

 The problem is to be able to collect, to set up in a liquid medium, a quantity of germs reproducible and relatively low.

 The use of a traditional inoculator (oese platinum wire, Pasteur looped pipette for example) shows the disadvantage of taking with each use quantities of germs too large and inreproductible.

 The drawback of a traditional inoculator lies in the fact that the surface of the inoculator in contact with the bacterial colony is variable according to the address of the manipulator and that the adhesion of the bacteria to the inoculator is variable depending on the action and the material of the inoculator.

 The device according to the invention overcomes these disadvantages. Indeed, its use makes it possible to standardize the gesture and to make reproducible the surfaces in contact with the germs. Moreover, the material used is chosen in that the amounts of germs adhering to the surface of the inoculum are reproducible according to the bacterial species.

 The device comprises two ends: - one end corresponds to the part by which the object is entered manually.

The other end corresponds to a cylinder for collecting bacterial colonies, rigid, of small diameter with a free section in a material chosen to promote the adhesion of the germs to be sampled.

 The use is standardized in that by holding the object vertically, the cylindrical end is pricked in the center of a colony until it contacts the bottom of the agar box. The surface in contact with the seeds is then dependent on the height of the agar medium in the box which is a constant. The vertical withdrawal of the device leaves on it constant amounts of germs.

The accompanying drawings illustrate the invention:
Figure 1 shows the device of the invention comprising a portion for gripping (1) and a part which comes into contact with the microorganisms (2).

 Figure 2a shows in section the cylindrical portion of the device (2) before use, placed vertically above the colony to be removed (3); the bacterial colony is present on the agar medium (4) in the plastic box whose bottom is shown in (5).

 Figure 2b shows in section the device in use when it reaches the bottom of the box (5) after passing through the bacterial colony (3).

 After removal of the device, the seeds (5) are deposited on a surface function of the height of the agar medium.

 For example, extruded polyethylene wire diameter 0.5 - 0.6 - 0.8 1 mm and chromed steel wire diameter 0.6 - 0.8 - 1 mm is used.

 The device is shaped (see Figure 1) in these different materials and used for different strains of bacteria taken after a culture of 18 h at 37 C on trypticase agar - soy.

 After sampling, the strains are taken by vigorously shaking the device for 30 seconds in 5 ml of liquid medium in order to detach the bacteria. The suspension is then digitized by dilution and seeding on trypticase soy agar. The test is performed three times.

One of the devices makes it possible to obtain results of between 1 and 5 106 Units
Colony forming per ml of resuspension (see Table 1).

Count (x 106 CFU / ml)

<tb><SEP> Strain <SEP> Assay <SEP> 1 <SEP> Assay <SEP> 2 <SEP> Assay <SEP> 3
<tb> C. <SEP> diversus <SEP> 4 <SEP> 3.8 <SEP> 3.5
<tb> C. <SEP> freundii <SEP> 2.9 <SEP> 3.5 <SEP> 2.7
<tb> E. <SEP> clcxacae <SEP> 3.1 <SEP> 3.6 <SEP> 2.9
<tb> E. <SEP> coli <SEP> 2,8 <SEP> 3,2 <SEP> 3,4
<tb> P. <SEP> mirabilis <SEP> 4.2 <SEP> 3.8 <SEP> 3.6
<tb> K. <SEP> oxytoc <SEP> 3,3 <SEP> 3,4 <SEP> 3,7
<tb> K. <SEP> pneumoniae <SEP> 3.8 <SEP> 4.2 <SEP> 4.0
<tb> M. <SEP> morganii <SEP> 4.5 <SEP> 4.1 <SEP> 4.3
<tb> P. <SEP> stuartii <SEP> 2.5 <SEP> 3.1 <SEP> 3.6
<tb> S. <SEP> marcescens <SEP> 3.5 <SEP> 3.8 <SEP> 3.8
<Tb>

Claims (5)

 1 - A device of defined geometry and composition for collecting bacterial or fungal colonies on an agar culture medium characterized in that it comprises an end for manually holding the device and a cylindrical end to collect the colonies and that its use makes it possible to standardize the sampling.  2 - A device according to claim 1, characterized in that the material is selected so as to obtain a reproducible sampling.  3 - A device according to claims 1 and 2, characterized in that the diameter is selected so as to obtain a reproducible sampling.  4 - A device according to claims 1 to 3, characterized in that its mode of use is defined by the choice of a colony of diameter greater than that of the object, then a vertical stitching in the center of the colony until at the bottom of the box, then a vertical shrinkage of the agar.  - An application of the use of the device according to one of claims 1 to 4 consisting of inoculating a liquid medium in a reproducible manner by vigorously shaking the device taken from the liquid medium to detach the picked germs.