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Description  |
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BACKGROUND OF THE INVENTION
This invention relates to microbiological testing apparatus and methods,
and more particularly to an improved system for facilitating the automatic
incubation and reading of microbiological test trays.
A number of different types of microbiological testing are carried out in
trays or strips (referred to herein collectively as "trays") which have a
number of chambers known as test wells or cupules. Such trays are used,
for example, to identify a microorganism, or to determine the
susceptibility of that organism to a number of antimicrobics, which latter
trays are called susceptibility trays. Typically, the test wells or
cupules in the identification trays contain complex chemicals or reagents
which in the presence of an active fermenting culture change color, become
cloudy or otherwise indicate that fermentation is or has taken place.
Similarly, in one known susceptibility test called the minimum inhibiting
concentration (MIC) test, the wells contain different dilutions of various
antimicrobics and a growth medium to determine the dilution level of the
antimicrobic which is sufficient to kill and/or inhibit growth of the
organism.
Conventionally, the test reagents and any growth medium or antimicrobics
are placed into the test wells in the form of an aqueous solution and
later lyophilized. A different combination of reagent or growth medium is
charged into different wells so that a great number of individual
reactions are performed in a physically small apparatus. For example, in
the MIC tests, a regular pattern of wells arranged in rows and columns
could be provided, each row of wells containing different antimicrobics.
Within a row, the concentration of the antimicrobic would increase from
well to well by a factor of, for example, 2. Of course, other dilution
ratios could be used.
When a test is to be performed, a microorganism is innoculated into each of
the test chambers with sufficient water to reconstitute the reagents. The
test trays are then incubated at an appropriate temperature, such as 35-37
degrees Celsius for an extended period of time. After a predetermined
period, the individual chambers are examined for the presence or absence
of a reaction or indication of color change, or a change in turbidity.
Heretofore, it is believed that the inspection of the wells for the
presence or absence of a reaction or indication was done manually at least
in part. Thus, individual trays each required the use of technician's time
in the preparation, innoculation, incubation and reading of the results.
Moreover, since different test trays might be needed to determine
different characteristics of the microorganisms, the reading of a variety
of different trays could be a fairly complex proceedure.
Systems have been provided for automating at least a portion of the reading
process. In one existing system for use in semi-automatically recording
the results of microbiological tests, a test tray having a plurality of
test wells arranged in a certain pattern is placed beneath a transparent
keyboard. A light source projects light through the tray and the keyboard
so that the user can view the tray with its test wells through the
keyboard. The keys of the keyboard correspond to the test wells, so that
the user presses the keys overlying those wells in which the certain test
results have occurred in order to record the results of the tests
conducted in the test wells. Such a method of reading the test wells
requires a highly skilled technician and a good deal of technician's time.
In addition, the incubation times for identification and susceptibility
trays may be quite different, with the result that the user will be
recording the results for a particular patient or specimen at two
different times, with the possibility that the identification and
susceptibility results might not be properly assigned to the same patient.
Moreover, the difference in times of incubation for identification and
susceptibility trays means that the user or operator must return twice to
the incubator for each patient.
SUMMARY OF THE INVENTION
Among the various aspects and features of the present invention may be
noted the provision of an apparatus for automating the microbiological
test procedure from incubation through the actual reading of the test tray
itself; the provision of such an apparatus which eliminates to a large
extent the necessity of having a highly trained technician read test
results; the provision of such an apparatus which insures that
identification and susceptibility results for the same patient remain
together; the provision of such an apparatus which is compatible with
currently available identification and susceptibility test trays; the
provision of such an apparatus that is flexible enough to use with a
number of different tray combinations; and the provision of such an
apparatus which is relatively economical to use.
Other aspects and features of the present invention will be in part
apparent and in part pointed out hereinafter.
Briefly, in a first aspect an automated microbiological testing apparatus
of the present invention includes an incubation chamber for incubating a
plurality of microbiological test trays such as susceptibility trays and
identification trays, an inspection station at which the test trays may be
inspected to determine the results of the microbiological tests, means for
moving any predetermined test trays desired from the incubation chamber to
the inspection station, and means for processing the image of the test
tray at the inspection station to determine test results.
In a second aspect of the invention, an automated microbiological testing
apparatus includes an incubation chamber for incubating a plurality of
microbiological test trays such as susceptibility trays and identification
trays, an inspection station at which the test trays may be inspected by
the apparatus to determine the results of microbiological tests, means for
moving any predetermined test trays desired from the incubation chamber to
the inspection station, and means for automatically determining test
results at the inspection station.
In a third aspect of the present invention, a carrier for a microbiological
tray includes a relatively rigid frame defining at least one central
opening suitable for holding and supporting a microbiological tray, the
tray having a pair of opposed, parallel shoulders suitable for riding on a
pair of parallel rails, and receiving means integrally formed in the frame
by means of which an external driving force may be applied to the frame to
move it along the rails.
In a fourth aspect of the present invention, a diagnostic microbiological
testing apparatus for obtaining test results from microbiological test
trays and strips such as susceptibility trays and identification trays,
each tray having a plurality of wells, comprises an inspection station at
which the test trays may be inspected to determine the results of the
microbiological tests, a video camera disposed to form images of the test
trays at the inspection station, and processing means for receiving the
images from the video camera and processing them to determine test
results.
In a fifth aspect of the present invention, a method of automatically
reading the results from microbiological test trays and strips such as
susceptibility trays and identification trays, each tray having a
plurality of wells, comprises the steps of making an image with a video
camera of a tray to be read, electronically analyzing only predetermined
areas of interest in the image made by the camera, which areas of interest
are substantially within the outlines of the tray wells in the image,
electronically determining for each well of interest the number of pixels
in each area of interest having an associated value that extends a
predetermined threshold for that area of interest, and electronically
assigning a binary partial result to each well based upon the number of
pixels which exceeded the predetermined threshold for each corresponding
area of interest.
In a sixth aspect of the present invention, a method of automatically
reading the results from microbiological test trays and strips such as
susceptibility trays and indentification trays comprises the steps of
moving a tray to be read to an inspection station, and electronically
reading the tray at the inspection station with a camera which remains
substantially stationary with respect to the tray while the reading of the
tray is occurring.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front elevation, with parts broken away for clarity, of
microbiological testing apparatus of the present invention;
FIG. 2 is a side elevation with parts broken away of the apparatus of FIG.
1;
FIG. 3 is a schematic of the internal components of the apparatus of FIG.
1;
FIG. 4 is a top plan, with parts broken away for clarity, of the apparatus
of FIG. 1;
FIG. 5 is a perspective illustrating a tray carrier and transporting means
of the present invention;
FIG. 6 is a top plan of the tray carrier of FIG. 5 showing portions of
identification and susceptibility trays in place;
FIG. 7 is a sectional view taken along line 7--7 of FIG. 6;
FIG. 8 is a front elevation of the carrier of FIG. 6;
FIG. 9 is a rear elevation of the carrier of FIG. 6;
FIG. 10 is a top plan of an identification tray suitable for use with the
apparatus of the present invention;
FIG. 11 is a sectional view taken along line 11--11 of FIG. 10;
FIG. 12 is a top plan of a susceptibility tray suitable for use with the
apparatus of the present invention;
FIG. 13 is an elevation of the tray of FIG. 12;
FIG. 14 is a schematic illustrating the reagent handling and identification
tray removal subassemblies of the apparatus of FIG. 1;
FIG. 15 is a perspective of the reagent reservoir of the apparatus of the
present invention;
FIG. 16 is a schematic of carrier presence sensing apparatus of the present
invention;
FIG. 17 is a schematic of elevator position sensing apparatus of the
present invention; and
FIG. 18 is a schematic of carrier position sensing apparatus of the present
invention.
Similar reference characters indicate similar parts throughout the several
views of the drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1, there is shown an automated microbiological
apparatus 11 of the present invention which includes an incubation chamber
13 for incubating a plurality of microbiological test trays, such as
susceptibility and identification trays 15 and 17 (see FIGS. 10 and 12),
carried in a common carrier 19 (FIG. 1). As shown in FIGS. 10 and 12,
susceptibility trays 15 and identification trays 17 each include a
plurality of wells or cupules 21 and 23 respectively arranged in rows and
columns. Referring back to FIG. 1, common carriers 19 are manually placed
through an access door (not shown) in a plurality of slots 25 in
incubation chamber 13. Slots 25 are vertically disposed in an elevator 27
which is movable vertically in incubation chamber 13 by a belt driven
screw drive 29, of which teflon coated drive screw 31 and precision
stepper motor 33 are shown in FIG. 1. Elevator 27 may include, by way of
example, two rows of thirty slots so that it may accomodate up to sixty
common carriers 19. By means of drive 29, any one of the slots 25 may be
moved to the level of the lowermost slot shown in FIG. 1 so that the
common carrier 19 therein may be removed through an access port from the
incubator for processing as discussed below. Temperature and humidity
within incubation chamber 13 are tightly controlled by means of a number
of sensors and a heater (not shown) and the humidifier discussed below.
More particularly, apparatus 11 also includes a housing 35 in communication
via the access port with the interior of incubation chamber 13. Housing 35
houses an inspection station 37 and means 39 for transporting common
carriers from slots 25 through the access port to the inspection station
37 and beyond as described below. A light source 41 is disposed above
inspection station 37 and a pair of video cameras 43 are disposed below
the inspection station. Alternatively, a pair of light sources may be
used, one above each camera. A waste bin 45 is also provided inside
housing 35 having a sensor system including a photodiode 46A and a
photodetector 46B for detecting when bin 45 is full. Housing 35 also
houses a dispensing head 47 for dispensing reagent into identification
trays 23, and a flipper system including a pair of flipper forks 49 for
removing identification trays or strips from common carriers 19.
Turning to FIG. 2, the two rows of slots 25 in elevator 27 are seen to be
disposed side by side in incubation chamber 13. Carrier transporting means
39 includes a pair of tracks 51 upon each of which ride a separate motor
driven carriage 53. Each carriage 53 carries a generally L-shaped rod 55
which is movable into a corresponding recess (see FIG. 4) in common
carrier 19 to move any desired carrier from its slot 25 in the incubation
chamber through one of the pair of access ports 56 to inspection station
37. Carriers 19 are moved from their slots to the inspection station along
a second pair of tracks 57.
Dispensing head 47 which is disposed above tracks 57 on the opposite side
of the inspection station 37 from incubation chamber 13, is carried by a
carriage 59 along a track 61 by a belt drive 63 including a belt drive
stepper motor 65. More particularly, dispensing head 47 is movable between
the extreme position shown above the rightmost track 57 to a corresponding
position generally to the left of the leftmost track 57 so that any
reagent may be dispensed into any cupule of the identification tray of a
common carrier on either track.
Although there are a pair of tracks 57 and a pair of cameras 43, it is
possibleuse a single light source 41 so long as cool and even illumation
of the inspection area is achieved. It has been found that a cold cathode
grid lamp equipped with a diffuser plate provides such illumination.
Alternatively, a pair of such lamps equipped with diffuser plates may be
used. For convenience, the inspection station can be divided into left and
right halves 37A and 37B, respectively. Below inspection station 37A and
between that inspection station and the corresponding camera 43 is a set
of filters 67 suitably mounted for moving any of a plurality of filters to
cover the field of view of camera 43. A similar set of filters is provided
between inspection station 37B and rightmost camera 43. These filters can
be mounted, for example, on a wheel 69 which is rotatable about its axis
by a motor 71 so that the desired filter can be rotated into place as
necessary. The filters can include color separation filters, neutral
density filters, and calibration devices. The placement of cameras 43 and
filter wheels 69 is selected so that the largest tray likely to be
encountered (e.g., a susceptibility tray) lies completely within the
viewing field of the camera, and requires no further motion once it is
positioned within the viewing field. Camera lens and camera to tray
distance are optimized to maximize the size of the tray in the field and
minimize optical distortion.
Turning now to FIG. 3, in addition to the components of apparatus 11
mentioned above there is shown a signal processing and controlling unit 73
for processing the images from cameras 43 and controlling the various
functions of apparatus 11. The signal processing part of unit 73 may
include image processors such as those under the trade designation System
20,000H by Unitron imagetek Systems of Plainview, New York; under the
trade designation IP-512 by Imaging Technology, Inc. of Woburn,
Massachusetts; under the trade designation Model 1000 by Image Technology
Corporation of Deer Park, New York; under the trade designation Scan 78/99
by Eikonix corporation of Bedford, Massachusetts; or under the trade
designation Model 109RM by LogE/Spatial Data Systems of Goleta,
California. Signal processing and controlling unit 73 not only analyses
the images from cameras 43 but also, in the manner described below,
determines from that analysis a partial test result for each well in a
tray and a total test result or results for each tray. Immediately to the
right of the signal processing and controlling unit 73 are shown two
temperature controllers 75 for controlling the temperature inside
apparatus 11 and particularly the temperature inside incubation chamber
13. Below signal processing and controlling unit 73 is a reservoir 77
which contains a plurality of (e.g., twenty) reagents as needed for
dispensing into identification trays 17. Pumping of reagent from the
reservoir to the dispensing head 47 is controlled by a set of reagent
pumps or solenoids 79. To the right of reagent solenoids 79 and suitably
mounted to opposite sides of the frame of apparatus 11 are a pair of
precision stepper motors 81 for driving the common carrier carriages 53.
More specifically, motors 81 each are operatively connected to a belt
drive 83 to drive the corresponding carriage 53 along its track 51 as
necessary to move common carriers from the incubation chamber to the
inspection station and to the area beneath the dispensing head 47 as
necessary. A barrier or bulkhead 85 is provided generally to the left of
dispensing head 47 and inspection station 37 in FIG. 3 to isolate waste
bin 45 from the inspection station. Bulkhead 85 includes an inclined plane
directly below dispensing head 47 so that wasted reagent (such as might
appear during priming of the dispensing head) is directed into waste bin
45. A plurality of motor control drives 87 are provided to control the
energization of motors 81 for the common carrier drive, of motor 33 for
the elevator drive, of motor 65 for the dispensing head drive, and of
motors 71 for the filter wheels. As will become apparent, signal
processing and controlling unit 73 includes control circuitry for
controlling the operation of apparatus 11 and in particular for
controlling motor drives 87 to move the various components of the
apparatus in a coordinated fashion as described below. For example, unit
73 may include a microcomputer suitably programmed to control the
apparatus. Alternatively, hard-wired circuitry could be provided to
perform the same function. A humidifier 89 is also provided to control the
humidity in apparatus 11 and particularly the humidity in incubation
chamber 13.
Turning now to FIG. 4, each track 57 is seen to include a pair of rails 91
and 93 extending from the access ports adjacent incubation chamber 13 past
the position of dispensing head 47. Rail 91 of each track extends beyond
rail 93 to facilitate the disposal of carrier 19. Tracks 51 also extend
generally from incubation chamber 13 generally to the opposite side of
apparatus 11. Each common carrier includes a recess 95 in which a puller
or grabber rod 55 may loosely rest to tow desired common carrier 19 from
its corresponding slot 25 in the incubation chamber to the position shown
in FIG. 4 at the inspection station. By moving the appropriate carriage 53
further to the left as seen in FIG. 4, common carrier 19 may be moved
underneath the dispensing head 47. And, if desired, further motion of
carriage 53 to the left in FIG. 4 results in the common carrier falling
off the end of rail 93 directly into waste bin 45.
Common carrier 19 (shown in more detail in FIG. 5) includes a generally
rectangular frame 97 having a cross-bar 99 extending thereacross to define
two central openings 101 and 103. Opening 101 is sized to receive an
identification tray such as shown in FIG. 10 while opening 103 is sized to
hold one or more susceptibility trays 15 as shown in FIG. 12. A ledge 105
about one-half way down in opening 101 along the perimeter thereof is
provided to support an identification tray 17 in central opening 101. A
pair of notches 107 are provided in the front wall of frame 97 to allow
the tines 109 of fork 49 to remove an identification tray from central
opening 101. Notches 107 extend below ledge 105 and the tines 109 are
sloped rearwardly so that as carrier 19 is moved to the position of fork
49, the tines pass under the identification tray and lift it free of
carrier 19. Between both forks 49 extends a striker flange 111 disposed
generally at the top rear of the forks.
Similarly, central opening 103 includes a ledge 113 for supporting one or
more susceptibility trays 15. A pair of positioning posts 115 extend up
from ledge 113 to accurately and securely position a susceptibility tray
in central opening 103. Common carrier 19 also includes an offset 117
extending generally out from the frame at the lower right-hand corner
thereof as shown in FIG. 5 for the purpose of insuring that common carrier
19 is loaded into incubation chamber 13 with the proper orientation.
Chamber 13 includes corresponding structure (not shown) which prevents the
carrier from being inserted into a slot 25 if it is turned the wrong way.
Also on the rightmost part of frame 97 is a set of recesses 119, each in
the shape of the numeral "8" which are provided to accurately define the
position at which the user writes down the patient or specimen
identification information for the trays carried by that particular
carrier 19. Recesses 119 also insure that the identification number can be
easily read by the image processing system of the present invention. FIG.
5 also illustrates one of a number of alternative embodiments (this one
labelled 51A) of track 51.
Looking now at FIGS. 6 and 7, frame 97 is seen to include a upwardly
sloping front surface 121 up which rod 55 may slide if necessary (although
it is preferred that such sliding not be necessary) as it is pushed into a
slot 25 in incubation chamber 13. At the uppermost extent of ramp 121, a
descending ramp 123 is provided which terminates in recess 95. Another
upwardly extending ramp 125 is disposed at the rear of recess 95 and it
terminates in a descending ramp 127 which descends to the general level of
the top of frame 97. Also shown in FIG. 6 is a portion of susceptibility
tray 15 in central opening 103 and a portion of identification tray 17 in
central opening 101. Frame 97 also includes a front lip 129 disposed
generally at the bottom of the frame. In FIG. 7, cross-bar 99 is seen to
be generally C-shaped and number recesses 119 are seen to be positioned on
the upper surface of a ledge 131 of carrier 19.
Frame 97 (FIG. 8) has a pair of shoulders 133 at the front which extend out
from the body of the carrier and provide the front surface from which ramp
121 inclines. Similarly, the rear view of carrier 19 (FIG. 9) reveals that
frame 97 also defines a surface or shoulder 135 for supporting carrier 19
as it is moved along tracks 57.
An identification tray 17 (FIG. 10) suitable for being carried in central
opening 101 of carrier 19 includes a pair of rows of wells or cupules 23
arranged in columns. The cupules may contain different reagents, some of
which are dispensed therein by dispensing head 47, for identifying various
microorganisms. Each cupule includes a generally circular open or aerobic
portion 137 and a generally closed or anaerobic portion 139 in fluid
communication with portion 137. Cupules 23 are in fact chambers where
reactions take place between the reagent therein and the particular sample
which has been innoculated into each cupule, which reactions can identify
the particular microorganism present in the sample. However, not each
reaction has the same result. In some reactions, a result would appear
only in section 137, which is exposed to air. Other reactions might occur
only in the anaerobic p | | |
