Patent US3832532A successfully refreshed from Google Patents.
US3832532A
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Method and apparatus for testing antibiotic susceptibility
Assignee: Warner Lambert Co LLC
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Filing: 1972-08-18
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Granted: 1974-08-27
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Expires: 1992-08-18
Abstract
Abstract The light scattering of a number of aliquots of a given bacterial/broth suspension, each containing a different antibiotic are rapidly measured and compared with the forward light scattering of a control suspension of the bacteria in the absence of antibiotic. The inhibitory effectiveness of each antibiotic on the growth of the bacteria is then computed from the substantially simultaneous readings and printed out. The bacterial/broth suspension samples are conveniently deposited in a disposable, plastic, transparent, compartmented container or cuvette into which antibiotic discs are introduced into all but one compartment (chamber) from a ganged disc dispenser. After a brief agitated incubation period of about three hours, the covette is inserted in a photometric analyzer which measures the intensity of light scattered at some angle to the incident beam by each sample chamber and compares it with the light scattered at the same angle by the control chamber to which no antibiotic has been added. The relative effectiveness of each antibiotic is computed and recorded to determine which of the antibiotics is most suitable for treating the patient. The partitioned cuvette includes a filling reservoir from which the inoculated broth is introduced as equal volume aliquots into the interconnected lobes of a row of double lobed chambers. Rotation of the partitioned cuvette transfers the equal volumes of broth inoculum from the interconnected lobes to the transparent and separated lobes of the chambers. Then different antibiotic discs are simultaneously dropped within apertured tubes which are located within all chambers except the control chamber. Elution of the antibiotics into the liquid samples begins immediately. The cuvette is then placed in an incubator/shaker for approximately 3 hours at approximately 36*C to promote bacterial growth and antibiotic elution. The light scattering readings are obtained at the end of the agitation/incubation period and the relative antibiotic effectiveness computed in an analyzer into which the cuvette is inserted and indexed past a light source. The light passes through a lens system which directs a beam of light successively through the transparent lobes of the cuvette. The readings are obtained at a predetermined angle of scatter of, for example, 35*. Initial analog signals are converted to binary digits and logarithms to simplify normalization of the antibiotic-mediated inhibition of bacterial growth by the total growth in the control chamber. The normalized growth inhibition values are printed out and rated on a scale of 0 (no inhibition, total resistance) to 100 (complete inhibition, total susceptibility). In addition the total growth, which has occurred in the control chamber during the agitation/incubation period, is printed out as a logarithmic difference (growth index). If insufficient growth has occurred in the control chamber (growth index less than 0.9), the cuvette may be reincubated and reread before disposal.
Inventors
- 👤 J Praglin
- 👤 D Longhenry
- 👤 Kie J Mc
- 👤 A Curtiss
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 09:39
CPC Classifications
G; G01; G01N; G01N35/00; Y; Y10; Y10S; Y10S435/00; Y10S435/808; Y10S435/809
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
196 words
A method of determining the inhibitory effectiveness of a number of different antimicrobial agents on the growth of a bacteria in a liquid sample comprising the steps of dividing said sample into a number of samples, simultaneously inoculating said samples with one each of said antimicrobial agents whereby said antimicrobial agents elute into said samples, maintaining one of said samples free of an antimicrobial agent for use as a control sample, incubating the samples for a brief period to develop potentially significant differences in the growth rate of the bacteria in each of them, agitating the incubated samples to obtain a uniform suspension of the bacteria grown in each of them, successively photometrically reading a light scattering characteristic in a limited portion of the uniform suspension in each sample indicative of the bacteria content in each of the samples, completing said readings for all of said samples within a brief time interval whereby the differences in said growth rate relative to time in said readings are substantially nullified and computing a comparison of said readings of the antimicrobial agent inoculated samples with the control sample to determine the relative effectiveness of each of the antimicrobial agents.
Claim 2
Independent Claim
196 words
A method of determining the inhibitory effectiveness of a number of different antimicrobial agents on the growth of a bacteria in a liquid sample comprising the steps of dividing said sample into a number of samples, simultaneously inoculating said samples with one each of said antimicrobial agents whereby said antimicrobial agents elute into said samples, maintaining one of said samples free of an antimicrobial agent for use as a control sample, incubating the samples for a brief period to develop potentially significant differences in the growth rate of the bacteria in each of them, agitating the incubated samples to obtain a uniform suspension of the bacteria grown in each of them, successively photometrically reading a light scattering characteristic in a limited portion of the uniform suspension in each sample indicative of the bacteria content in each of the samples, completing said readings for all of said samples within a brief time interval whereby the differences in said growth rate relative to time in said readings are substantially nullified and computing a comparison of said readings of the antimicrobial agent inoculated samples with the control sample to determine the relative effectiveness of each of the antimicrobial agents.
Claim 3
Dependent Claim
31 words
A method as set forth in claim 1, wherein the elution of the antimicrObial agents during said incubation is standardized and said agitation is performed by uniform shaking during said incubation.
Claim 4
Dependent Claim
19 words
A method as set forth in claim 1 wherein said photometric reading is accomplished by a light scattering method.
Claim 5
Dependent Claim
17 words
A method as set forth in claim 3 wherein said light scattering method utilizes a light source.
Claim 6
Dependent Claim
14 words
A method as set forth in claim 4 wherein said light is white light.
Claim 7
Dependent Claim
21 words
A method as set forth in claim 1 wherein said samples are deposited, incubated and photometered in a transparent compartmented container.
Claim 8
Dependent Claim
22 words
A method as set forth in claim 6 wherein said samples are inoculated with antimicrobial agents by a ganged antibiotic disc dispenser.
Claim 9
Dependent Claim
17 words
A method as set forth in claim 7 wherein said samples are incubated in a shaking incubator.
Claim 10
Dependent Claim
17 words
A method as set forth in claim 8 wherein said incubation is performed for about 3 hours.
Claim 11
Independent Claim
158 words
A method of determining the inhibitory effect of a number of different antimicrobial agents on the growth of a bacteria in a liquid sample comprising the steps of dividing said sample into a number of samples, inoculating said samples with one each of said antimicrobial agents, maintaining one of said samples free of an antimicrobial agent for use as a control sample, uniformly incubating said samples for a brief period to develop potentially significant differences in the growth rate in each of them, agitating the incubated samples to obtain a uniform suspension of the bacteria grown in each of them, directing a light beam through a limited portion of the uniform suspension in each of said samples, photometrically determining the light scatter from each of said samples in said beam, and computing a comparison of said reading of the antimicrobial agent inoculated samples with the control sample to determine the relative effectiveness of each of the antimicrobial agents.
Claim 12
Independent Claim
158 words
A method of determining the inhibitory effect of a number of different antimicrobial agents on the growth of a bacteria in a liquid sample comprising the steps of dividing said sample into a number of samples, inoculating said samples with one each of said antimicrobial agents, maintaining one of said samples free of an antimicrobial agent for use as a control sample, uniformly incubating said samples for a brief period to develop potentially significant differences in the growth rate in each of them, agitating the incubated samples to obtain a uniform suspension of the bacteria grown in each of them, directing a light beam through a limited portion of the uniform suspension in each of said samples, photometrically determining the light scatter from each of said samples in said beam, and computing a comparison of said reading of the antimicrobial agent inoculated samples with the control sample to determine the relative effectiveness of each of the antimicrobial agents.
Claim 13
Dependent Claim
24 words
A method as set forth in claim 10 wherein said computing is performed in a photometric analog mode which is immediately converted to digital.
Claim 14
Dependent Claim
16 words
A method as set forth in claim 11 wherein said digital computing is performed in binary.
Claim 15
Dependent Claim
16 words
A method as set forth in claim 12 wherein said binary digital computing is also logarithmic.
Claim 16
Dependent Claim
44 words
A method as set forth in claim 12 wherein a sequence of operations are controlled by a read only memory whereby a division in binary is performed and converted to a base ten number to achieve a resultant answer in a binary coded decimal.
Claim 17
Dependent Claim
26 words
A method as set forth in claim 10 wherein the elution of the antimicrobial agents during said incubation is standardized by uniform shaking during said incubation.
Claim 18
Dependent Claim
17 words
A method as set forth in claim 15 wherein said samples are incubated in a shaking incubator.
Claim 19
Dependent Claim
18 words
A method as set forth in claim 10 wherein said light scattering method utilizes a white light source.
Claim 20
Dependent Claim
14 words
A method as set forth in claim 17 wherein said light is white light.
Claim 21
Dependent Claim
293 words
A photometric apparatus for determining the relative differences in reaction inhibition effectiveness of a number of inhibitory agents in a solution by determining their effect on the light scattering characteristics of a number of different solution samples comprising a light source, a carriage disposed adjacent said light source, a removable transparent compartmented container having a plurality of chambers for holding each of said sample solutions, said carriage being constructed and arranged for holding and moving said compartmented container past said light source in a path of travel, said chambers each having a wall which is optically transparent at a predetermined acute angle to said light source and to the forward light scatter caused in said solution in said chamber by said light source, rapid indexing means on said carriage for successively positioning each of said chambers at a predetermined position for a brief time with said wall at said predetermined acute angle in front of said light source whereby light scattering readings at said predetermined acute angle are obtained and whereby the differences in said readings relative to time are substantially nullified, a light meter disposed opposite said light source from said predetermined position and spaced therefrom on the opposite side of said path of travel of said compartmented container, said light meter being disposed at said predetermined acute angle relative to the beam of said light source passing through said chambers whereby it reads the amount of light scattered by each of said samples at said predetermined acute angle in said brief time, and computing means connected to said light meter for computing and calculating the relative light scattering characteristics of the solutions in each of said chambers in said brief time whereby the inhibitory characteristics of said inhibitory agents are determined.
Claim 22
Dependent Claim
293 words
A photometric apparatus for determining the relative differences in reaction inhibition effectiveness of a number of inhibitory agents in a solution by determining their effect on the light scattering characteristics of a number of different solution samples comprising a light source, a carriage disposed adjacent said light source, a removable transparent compartmented container having a plurality of chambers for holding each of said sample solutions, said carriage being constructed and arranged for holding and moving said compartmented container past said light source in a path of travel, said chambers each having a wall which is optically transparent at a predetermined acute angle to said light source and to the forward light scatter caused in said solution in said chamber by said light source, rapid indexing means on said carriage for successively positioning each of said chambers at a predetermined position for a brief time with said wall at said predetermined acute angle in front of said light source whereby light scattering readings at said predetermined acute angle are obtained and whereby the differences in said readings relative to time are substantially nullified, a light meter disposed opposite said light source from said predetermined position and spaced therefrom on the opposite side of said path of travel of said compartmented container, said light meter being disposed at said predetermined acute angle relative to the beam of said light source passing through said chambers whereby it reads the amount of light scattered by each of said samples at said predetermined acute angle in said brief time, and computing means connected to said light meter for computing and calculating the relative light scattering characteristics of the solutions in each of said chambers in said brief time whereby the inhibitory characteristics of said inhibitory agents are determined.
Claim 23
Dependent Claim
34 words
A photometric apparatus as set forth in claim 19 wherein said indexing means comprises slots in said carriage and photoelectric means for successively stopping each of said samples in front of said light source.
Claim 24
Dependent Claim
18 words
A photometric apparatus as set forth in claim 19 wherein said light source comprises a white light source.
Claim 25
Dependent Claim
22 words
An apparatus as set forth in claim 19 wherein said computing means comprises a photometric analog immediately converted to digital computing means.
Claim 26
Dependent Claim
19 words
An apparatus as set forth in claim 22 wherein said digital computing means comprises a binary digital computer means.
Claim 27
Dependent Claim
21 words
An apparatus as set forth in claim 23 wherein said binary digital computer means is logarithmic to facilitate obtaining relative values.
Claim 28
Dependent Claim
42 words
An apparatus as set forth in claim 23 wherein a read only memory is provided having a sequence of operations for performing a division in binary scaled in a base ten manner to achieve a resultant answer in a binary coded decimal.
Claim 29
Dependent Claim
38 words
A photometric apparatus as set forth in claim 19, wherein a holding finger is disposed in each of said chambers for holding said inhibitory agent and a port in each of said chambers for inserting said inhibitory agents.
Claim 30
Dependent Claim
24 words
An apparatus as set forth in claim 26, wherein said ports are capable of simultaneous openings to facilitate rapid insertion of said inhibitory agents.
Claim 31
Dependent Claim
35 words
An apparatus as set forth in claim 19, wherein said compartmented container has a plurality of test lobes, and said test lobes having a curved shape to facilitate the obtaining of forward light scatter readings.
Claim 32
Dependent Claim
32 words
A photometric apparatus as set forth in claim 19, wherein said chambers are interconnected by passageways of relatively small cross-sectional area whereby said sample solutions are rapidly equally divided between the chambers.
References Cited (Backward Citations)
US3322956A
Cited
US3520660A
Cited
US3531202A
Cited
US3561875A
Cited
US3574063A
Cited
US3551062A
Cited
US3701601A
Cited
US3553444A
Cited
US3627424A
Cited
US3609047A
Cited
US3718439A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-26 | 1978-02-25 | 1978-08-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-26 | 1982-02-25 | 1982-08-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-26 | 1986-02-25 | 1986-08-27 | $7700.00 | Window Closed / Lapsed |