Microbial retrieval and sampling pipette with a removable cover

This invention (FIGS. 1-4) relates to a pipette-syringe combination employing a wire probe attached to the syringe plunger to remove a cover provided over the pipette orifice. One edge of the protective cover is attached via an elastomeric strap to the pipette. When the cover is forced away from the pipette orifice, the elastomeric strap pulls the cover away from, and prevents return of the cover over, the pipette orifice. A suitable sample may then be drawn in the pipette at the location of the cover removal. In the embodiment of FIGS. 5-7, the protective cover is manually removed to obtain a surface growth sample by the wire probe and the sample retracted within the pipette. A quantity of nutrient broth is added to the pipette, the pipette sealed by manually replacing the protective cover, with subsequent incubation of the sealed pipette in an incubator. After incubation, the pipette is agitated to distribute the growth, the cover is manually removed and controlled quantities of the broth transferred to a number of tubes for further study.

FIELD OF THE INVENTION 
This invention relates generally to sampling devices and relates 
specifically to a pipette-syringe combination retrieval and sampling 
device having a remotely removable, protective cover disposed over the 
orifice thereof. 
BACKGROUND OF THE INVENTION 
In the field of science, especially in microbiology, the need to obtain a 
representative sample is a constant challenge. It has been often quoted 
"that a laboratory test is only as good as the sample." This requirement 
for a representative sample applies, not only to those specimens from a 
clinical source, industrial processes, or polluted water, but also 
includes daily operations in the laboratory. For example, a classical 
microbiological technique is the retrieval and transfer of growth from a 
tube of nutrient broth. In the usual procedure a loop of growth is removed 
and streaked on an agar surface or transferred to another tube of broth 
for further incubation. In some cases a sterile pipette is used instead of 
a wire loop. 
In order to encourage the growth of a wide range of organisms, a small 
amount of agar (0.1%) may be added to nutrient broth. This amount of agar 
supports the development of obligate anaerobes, micro-aerophiles and 
aerobes growing in layers with aerobes at the surface and anaerobes at the 
bottom of the growth container. If the concentration of agar is increased 
to a range of 0.16 to 0.4%, subsurface colonies will develop ranging in 
shape from elongated, diffuse to compact tear shaped. This concentration 
is generally referred to as soft agar. Microbial growth under these 
conditions does not readily lend itself to transfer with either a wire 
loop or pipette, since as the loop or pipette is moved through the layers 
of growth, contamination occurs before the desired area of growth is 
reached. There is therefore a definite need in the art for an apparatus 
for retrieving a representative uncontaminated sample of bacterial growth 
from specific areas within a growth medium. Subsurface bacterial colony 
growth in soft agar is further elaborated on in applicant's co-pending 
patent application, Ser. No. 07/751,182 filed Aug. 28, 1991, and the 
subject matter of which is incorporated by reference herein. 
It is an object of the present invention to provide an improved 
pipette-syringe combination that permits retrieval of organism samples in 
a specific area of growth without prior contamination of the sampling 
device by surrounding media. 
Another object of the present invention is an improved pipette-syringe 
combination that is operable in agar containing and agar free media. 
A further object of the present invention is an apparatus and process for 
retrieving a representative sample from subsurface growth in a media 
source. 
An additional object of the present invention is an apparatus capable of 
recovering organisms at various depths in water columns of eco-systems. 
Still another object of the present invention is a novel liquid sampling 
device for the collection of liquid samples from various depths of samples 
or containers of polluted water, fermentation liquids, food processing 
operations, and the like. 
Another object of the present invention is a novel sampling pipette that 
also can serve as a growth chamber for the collected sample. 
Yet another object of the present invention is a process of obtaining a 
representative sample in a pipette, adding nutrient broth to the pipette 
and incubating the sample in the nutrient broth containing pipette before 
transferring the accumulated culture growth to a number of tubes. 
SUMMARY OF THE INVENTION 
The foregoing and additional objects are attained, according to one aspect 
of the present invention, by providing a wire probe inside a conventional 
plastic pipette-syringe combination and securing the wire probe to the 
bottom of the pipette plunger in the syringe. The length of the wire probe 
is selected such that the unattached end thereof is maintained within the 
pipette when the plunger is retracted and is extended a controlled 
distance from the pipette sampling orifice when the plunger is fully 
depressed. 
By providing the wire probe attached to the plunger, the movement of the 
wire probe inside the pipette is controlled by the pulling and pushing 
action of the plunger inside the barrel of the syringe. A removable 
plastic cap is disposed over the pipette orifice and has one edge surface 
thereof attached to the exterior of the pipette wall via an elastic strap. 
The downward motion of the wire probe, responsive to pushing on the 
plunger, pushes the removable cap away from the pipette orifice and the 
elastic strap acting on the edge of the cap retracts the cap away from, 
and prevents the cap from again covering, the pipette orifice as the wire 
probe is retracted by an upward pull of the syringe barrel. The upward 
pull of the plunger simultaneously creates a suction force that forces 
sample to flow into the pipette. The plastic pipette-syringe combination 
is designed as a sterile disposable, or "one use only" unit. 
In another aspect of the present invention, the removable cap is removed by 
the same wire probe, or by hand, and the wire probe extended to touch the 
surface colony from the surface of a petri dish. The wire probe is then 
retracted, the tip of the pipette placed in nutrient broth and sterile 
media drawn into the pipette by the pulling action of the plunger-syringe 
barrel. The orifice cover is then manually placed over the pipette tip for 
hermetically sealing of the pipette orifice. The entire pipette is then 
placed in an incubator for 18 to 24 hours at the desired temperature, 
usually 37.degree. C. The accumulated growth is then uniformly distributed 
by a back-and-forth rocking motion of the pipette and, after manual 
removal of the orifice cover, the growth can be accurately transferred to 
a number of tubes by a downward action of the syringe plunger. 
In each aspect of the present invention, the plastic pipette-syringe 
combination is designed to be a disposable, "one use only" unit.

DETAILED DESCRIPTION 
Referring now to the drawings and more particularly to FIGS. 1 and 2, there 
is shown a part schematic view of the preferred embodiment of a disposable 
pipette-syringe combination, according to the present invention and 
designated generally by reference numeral 10. A first end of pipette 10 is 
formed of an elongated syringe barrel 11 having a plunger 13 slidably 
disposed therein. One end of barrel 11 is provided with an external bead 
14 and serving to limit the movement of plunger 13 therein. 
Plunger 13 is provided with a beaded end 15 that engages bead 14 on barrel 
11 when the plunger is fully depressed. The other end of plunger 13 is 
provided with a rounded end 16 that engages the bottom 17 of barrel 11 
when the plunger is fully depressed. An elongated, hollow, pipette tube 
20, having graduated indicia 21 thereon, has one end secured in fluid 
communication with an opening 22 in the bottom 17 of barrel 11. 
Pipette tube 20 is provided with a tapered tip terminating in an orifice 
26. A removable, plastic, protective cover 27 is disposed over orifice 26 
and extends over a portion of the length of tube 20. An elastomeric strap 
30 is attached at one end to the exterior of pipette tube 20, as 
designated by reference numeral 31. The other end of elastomeric strap 30 
is secured to an edge surface of removable cover 27, as designated by 
reference numeral 32. Elastomeric strap 30 is under tension when orifice 
cover 27 is disposed over pipette orifice 26, as illustrated in FIGS. 1 
and 2. 
An elongated wire probe 35 is secured to the rounded end 16 of plunger 13 
and extends through opening 22 and along the internal hollow portion of 
pipette tube 20. The length of wire probe 35 is selected such that the 
unattached blunt end 36 thereof is maintained within the pipette tube 20 
when plunger 13 is retracted, and is extended a controlled distance from 
pipette tube orifice 26, when plunger 13 is fully depressed, or when 
rounded end 16 thereof is in engagement with bottom 17 of barrel 11. 
Referring now more particularly to FIG. 3, wire probe 35 is shown depressed 
(via movement of plunger 13) sufficiently for blunt end 36 thereof to 
engage the bottom of, and start movement of cover 27 away from its orifice 
covering position. Protective cover 27 is frictionally disposed on pipette 
tube 20 but is removable therefrom by the force of wire probe 35 acting 
against the interior bottom surface thereof. The construction of the 
bottom surface of cover 27 is of adequate thickness, or provided with 
suitable covering, to prevent puncture thereof by the blunt end 36 of wire 
probe 35 during removal. 
As illustrated, the tension of elastomeric strap 30 acting on cover 27 
causes protective cover 27 to tilt at an angle once an edge thereof clears 
the end of pipette tube 20 and orifice 26. As probe wire 35 is retracted 
back into pipette 20, tension on elastomeric strap 30 is no longer 
maintained and the elastomeric strap 30 pulls orifice protective cover 27 
to the side of pipette 10 and prevents it from returning to cover orifice 
25 (FIG. 4). The removal of protective cover 27 from orifice 26 is 
accomplished entirely by the action of plunger 13, probe wire 35 and 
elastomeric strap 30. Thus, pipette tube 20 may be inserted through soft 
agar or fluid media to the exact point from which it is desired to obtain 
a sample without exposing orifice 26 to possible contaminants away from 
the media surrounding the sample area. 
Referring now to FIGS. 5-7 a slight modification and an additional 
utilization of the present invention will now be described. In this 
embodiment, as illustrated in FIG. 5, a Petri dish 50 having a quantity of 
nutrient agar 51 supporting culture growth in colonies 52 thereon is 
shown. Pipette 10 is of the same construction as that previously described 
for the embodiment shown in FIGS. 1-4, and like reference numerals are 
employed for the same parts thereof. A modified protective plastic cover 
57, employed in this embodiment, is provided with an extension tab 58 to 
permit easy grasping by hand. 
In operation of this embodiment, protective plastic cover 57 may be 
remotely removed by action of plunger 13, as in the previously described 
embodiment, or cover 57 may be removed by the operator grasping tab 58 
thereon and manually removing it. In either removal operation, elastomeric 
strap 30 maintains cover 57 attached to pipette tube 20. After removal of 
cover 57 from orifice 27, wire probe 35 is extended via action of plunger 
13 and a portion of tip 36 touched or embedded within surface colony 52 in 
an open petri dish 50. 
As illustrated in FIG. 6. The probe wire 35 is then retracted, and orifice 
26 of pipette tube 20 is placed into nutrient broth 60 within container 61 
and a quantity of sterile broth media 60 is drawn into pipette tube 20 by 
the pulling action of the plunger 13 acting within syringe barrel 11. 
Protective cover 57 is then grasped by the operator, utilizing extension 
tab 58, and again (manually) placed over pipette orifice 25 to 
hermetically seal the end of pipette tube 20. Plastic cover 57 is designed 
to stretch fit over pipette tube 20 for hermetically sealing thereof. 
Protective cover 57 may be provided with internally and circumferentially 
disposed ribbed surfaces to act as O-ring seals to assist in maintaining 
the hermetically sealed condition between the cover and pipette tube end, 
if so desired. As in the previously described embodiment, the bottom 
surface of cover 57 is constructed such that puncture thereof by the blunt 
end 36 of wire probe 35 is prevented during removal of the protective 
cover 57 by wire probe 35. 
After sealing the quantity of nutrient broth 60 within pipette tube 20, the 
entire pipette 10 is placed within a suitable incubator 70 (FIG. 7) for 18 
to 24 hours at 37.degree. C. After incubation, the accumulated growth is 
uniformly distributed by a back-and-forth rocking motion of pipette 10. 
After again removing protective cover 27, the growth can be accurately 
transferred to a number of tubes by a the downward action of syringe 
plunger 13. 
Although the invention has been described as primarily used for the 
sampling of microbial cultures, the invention is not so limited. Pipette 
10 may also be employed to obtain fluid samples in a water column to 
collect samples at various levels therein, in water pollution studies, 
industrial sources, such as food processing operations, and the like. 
Most of the component parts of the present invention are formed of 
conventional clear or translucent plastic such as polyvinyl chloride, 
polyethylene or other rigid plastic. Elastomeric strap 30 in the preferred 
embodiment is formed of a conventional rubber band, of suitable size and 
resiliency, to be stressed while covers 27 and 57 are covering orifice 36 
and to retract the covers to the side of pipette tube 20 when removed from 
their covering position. Any conventional bonding or adhesive material, 
such as commercially available "super glue", may be employed to attach the 
ends of elastomeric strap 30 to pipette tube 20 and to protective covers 
27 and 57 prior to packaging and sterilizing of pipette 10. Pipette 10 may 
be any of various conventional sizes and the entire pipette is a 
disposable unit intended to be delivered to the site of use in a sterile 
condition and adapted for "only-one-use". 
The specific embodiments of the invention described herein are intended to 
be illustrative only and are therefore not to be deemed as exhaustive. 
There are numerous various modifications and variations of the invention 
that will be readily apparent to those skilled in the art in the light of 
the above teachings. 
For example, in the embodiment illustrated in FIGS. 5-7, carbohydrate 
fermentation patterns and antibiotic sensitivity could be determined by 
arraying along wire probe 35 commercially available disks containing the 
appropriate dehydrated sugar or antibiotic. 
Other changes and modifications of the specific embodiments disclosed 
herein will be apparent to those skilled in the art. It therefore to be 
understood that, within the scope of the appended claims, the invention 
may be practiced other than as specifically described herein.