Microbial detection assembly

A microbial detection assembly is disclosed which includes a tubular body, a pierceable septum, and a plunger. The tubular body defines a longitudinal axis and has a first end and a second end. The pierceable septum is configured to seal the first end of the tubular body. The plunger head is configured to substantially close the second end of the tubular body. Together, the plunger head, the pierceable septum, and the tubular body define a reservoir dimensioned to receive a medium and a sample substance. Additionally, the plunger head is positioned and is movable within the tubular body in response to changes in pressure within the reservoir.

BACKGROUND

1. Technical Field

The present disclosure relates to the field of medical fluid devices, in particular, a microbial detection assembly for detecting microbial contents of a sample substance.

2. Description of Related Art

In the medical field, a common medical procedure is to test for the presence of bacteria in a patient's body fluids, particularly blood. Traditionally, a blood culture vial having a bacterial growth medium (e.g., soy broth) and head space (e.g., nitrogen or oxygen) is provided and a small quantity of blood is injected through a pierceable septum into vial. The vial is incubated at a specified temperature and monitored for bacterial growth. If the blood contains bacteria, the bacterial growth generates carbon dioxide. Monitoring the carbon dioxide content can be accomplished by methods well established in the art, including radiochemical, infrared absorption at a carbon dioxide spectral line, or pressure/vacuum measurement.

Upon determination of a positive blood sample (i.e., blood containing bacteria) a clinician may need to withdraw the positive blood sample to perform further medical examinations. Withdrawal and transfer of a positive blood sample from a known blood culture vial can be cumbersome and typically requires insertion of a syringe needle into the pierceable septum for subsequent withdrawal of the sample into a transfer syringe followed by removal of the sample from the transfer syringe. Use of the transfer syringe and syringe needle increases the risk of an accidental needle stick to a clinician and potential contamination of the blood.

SUMMARY

A microbial detection assembly is disclosed which includes a tubular body, a pierceable septum, and a plunger. The tubular body defines a longitudinal axis and has a first end and a second end. The pierceable septum is configured to seal the first end of the tubular body. The plunger head is configured to substantially close the second end of the tubular body. Together, the plunger head, the pierceable septum, and the tubular body define a reservoir dimensioned to receive a medium and a sample substance. Additionally, the plunger head is positioned and is movable within the tubular body in response to changes in pressure within the reservoir.

In embodiments, a securing structure is configured to secure the pierceable septum to the first end of the tubular body. The securing structure may be constructed from metal, plastic, or epoxy. In addition, the securing structure may be fastened to the end of the tubular body by either crimping, screwing, pressing, gluing, or welding.

In embodiments, the microbial detection assembly includes a first retaining structure and a second retaining structure that are disposed within the tubular body. In this configuration, the plunger head is movable along the longitudinal axis between a first position and a second position that is defined by the first and second retaining structures during a microbial detection period.

The tubular body may be constructed from plastic or glass. The pierceable septum may be constructed from rubber composites, silicone composites, or gel composites. In addition, the tubular body defines a neck portion that has an annular flange portion, which terminates into the first end of the tubular body.

The plunger head includes a plurality of annular ribs which are disposed annularly about the plunger head. The annular ribs are positioned to slidably and sealingly engage with an inner wall of the tubular body.

In embodiments, the tubular body and the plunger head has a lubricous material. The first and second retaining structures may be annular rings or injection molded nubs. In addition, the plunger head may be movable along the longitudinal axis beyond the first retaining structure to a third position adjacent the neck portion of the tubular body.

In embodiments, the microbial detection assembly includes a sensor that is configured to indicate levels of carbon dioxide within the reservoir of the tubular body. The sensor may be a colorimetric sensor.

In embodiments, the microbial detection assembly includes a plunger rod that has an elongate plunger shaft adapted to releasably engage the plunger head. The plunger rod and the plunger head are movable along the longitudinal axis to dispense the medium and the sample substance from within the reservoir. In addition, the microbial detection assembly may further include a needle assembly that is mounted on the first end of the tubular body.

DETAILED DESCRIPTION

Referring initially toFIGS. 1-5, a microbial detection assembly, which may also be referred to as a blood culture vial, is generally depicted as numeral10. Microbial detection assembly10, generally, includes a tubular body12, a septum18and a plunger head22, which together define a reservoir26. The reservoir26is configured to contain a bacterial growth medium28having a head space26aincluding nitrogen and/or oxygen and a sample substance34, e.g., blood. Briefly, if the blood contains bacteria, bacterial growth will occur. The bacterial growth generates carbon dioxide, which results in a pressure increase within reservoir26. As a result, plunger head22moves within tubular body12towards a bottom end16of tubular body during a microbial detection period, indicating to a clinician that bacteria is present in the blood. A more detailed description of the aforementioned arrangement will be discussed further below.

FIGS. 4 and 5depict the tubular body12having a top end14and a bottom end16. Tubular body12may be made of a material including, but not limited to, plastic, glass, or any other suitable container material. Microbial detection assembly10further includes a septum18configured to close, i.e. seal, the open first end14of the tubular body12.

Septum18is pierceable such that a sharp object, for example, a needle32of a syringe assembly30(as shown inFIG. 4), can penetrate through the surface of the septum18and into reservoir26of tubular body12. In this manner, syringe assembly30allows a clinician to deposit a sample substance34, for example, blood, into reservoir26. When the syringe assembly30is removed from the tubular body12(as shown inFIG. 5), the septum18, which is constructed from a resilient material, seals reservoir26. The pierceable septum18may be made of a suitable pierceable resilient material including, but not limited to, rubber, silicone, gel, or the like.

The top end14of tubular body12defines a neck portion14awhich includes an annular flange portion14b. Septum18is tightly held in place over top end14by a securing structure20. Securing structure20may include an annular aluminum crimp that is crimped around top end14and further extends under the annular flange portion14b. Alternatively, the securing structure20may be any suitable securing material, including, but not limited to, metal, plastic, epoxy, or the like. It is also envisioned that securing structure20may be fastened to the top end14by any suitable fastening technique including, but not limited to, crimping, screwing, pressing, gluing, welding, or the like.

As mentioned above, the plunger head22is configured to substantially close the bottom opening16of the tubular body12. Plunger head22includes one or more plunger seals or annular ribs22a-cpositioned about plunger head22. Each rib22a-cis spaced from an adjacent rib and is dimensioned to slidably and sealingly engage an inner wall26bof tubular body12. In embodiments, the inner wall26bof reservoir26and plunger head22may be made of or include a lubricous material (e.g., polypropylene, polyethylene, etc.), such that plunger head22can press against inner wall26bwith sufficient force to provide a seal, while still be capable of sliding movement within tubular body12.

Referring toFIGS. 4 and 5, microbial detection assembly10further includes retaining structures24aand24b. Retaining structures24aand24bare positioned to retain plunger head22within a predetermined area along the tubular body12during the microbial detection period. Retaining structure24ais positioned in a central to bottom portion of the tubular body12and retaining structure24bis positioned towards bottom end16of the tubular body12.

Retaining structures24aand24bmay be, for example, annular rings, which in turn, may be removable and/or adjustable. The annular rings are disposed, in a radial configuration, within the walls of tubular body12. It is envisioned that retaining structures24aand24bmay be fixedly secured at a predetermined position within tubular body12. However, those skilled in the art will appreciate that retaining structures24aand24bmay be adjustable to any position if desired. In alternate embodiments, retaining structures24aand24bmay be injection molded nubs integrally formed within the walls of tubular body12.

The microbial detection device10may be a, so called, “graduated” microbial detection device10. In this configuration, the tubular body12may have indicia indicating to a clinician the distance the plunger head22has traveled during the microbial detection period. Additionally or alternatively the tubular body12may have indicia indicating to a clinician the amount of volume the reservoir26contains.

In use, as shown inFIGS. 4-5, a sample of blood34is deposited into reservoir26by way of syringe assembly30or any other type of substance transporting device. In particular, needle32of syringe assembly30is introduced into septum18and into reservoir26, where a clinician expels some or all of the contents of syringe assembly30. The blood sample34then mixes with the bacterial growth medium28, which may be for example, a soy broth. If bacteria is present in the blood sample34, bacterial growth takes place in the reservoir26, resulting in generation of carbon dioxide within the headspace26a. Headspace26aincludes a gas such as oxygen or nitrogen. The generated carbon dioxide results in a pressure increase within the reservoir26, which, in turn, forces the plunger head22to move in a downward direction from a first position to a second position, as depicted by directional arrow “A” inFIG. 5. This, in turn, gives a visual indication to a clinician that bacterial growth has occurred within reservoir26of microbial detection assembly10, thus identifying to a clinician that bacteria is present in the blood sample.

FIGS. 6 and 7illustrate an alternative embodiment of the presently disclosed microbial detection assembly shown generally as110. Microbial detection assembly110is substantially similar to microbial detection assembly10but includes a sensor140. Microbial detection assembly110, similarly to microbial detection assembly10, includes a tubular body112, a septum118and a plunger head122, which together, define a reservoir126. In this arrangement, the reservoir126is configured to contain a bacterial growth medium128having a head space126aincluding oxygen and/or nitrogen, and a sample substance134(e.g., blood). When bacteria is present in the substance134, carbon dioxide gas is generated as discussed above. As a result and depicted inFIG. 7, plunger head122moves within tubular body112towards bottom second end116, indicating to a clinician that bacteria is present. Alternatively, plunger head122need not move and sensor140may provide an indication that carbon dioxide has been generated, thus indicating that the blood sample contains bacteria.

In embodiments, sensor140is disposed within the tubular body112of microbial detection assembly110to indicate to a clinician the levels of carbon dioxide within reservoir126. Sensor140may be a colorimetric sensor, which in turn, responds to changes in carbon dioxide concentration emitted by bacteria by changing color or by changing fluorescence intensity. In embodiments, individual light sources, for example, colorimetric instruments, fluorometric instruments, and/or light emitting diodes may be used as an indicator for sensor140.

FIGS. 8A-8Cillustrate another embodiment of the presently disclosed microbial detection assembly shown generally as210. Microbial detection assembly210includes a plunger head222configured to receive a plunger rod230. Plunger head222and plunger rod230may be as described in U.S. Publication No. US 2008-0082055 A1 to Lloyd et al, the entire contents of which are hereby incorporated by reference herein. The plunger rod230has an elongate plunger shaft231configured and dimensioned for slidable disposition within tubular body212of microbial detection assembly210. Tubular body212, similarly to tubular body12, includes retaining structures224aand224bfor positioning plunger head222within a predetermined area along the tubular body212during the microbial detection period. Plunger shaft231includes a proximal end232which extends out of bottom end216of microbial detection assembly210and defines a finger engagement surface232a. With the plunger head222disposed within the inner side wall226bof the tubular body212along the longitudinal axis “X”, the distal end234of plunger rod230is selectively connectable to a receiving channel222aof plunger head222. In use, a clinician can utilize microbial detection assembly210as a syringe assembly by simply attaching plunger rod230to tubular body212, as described above, and applying a force to finger engagement surface232aof plunger rod230to dispense a positive sample from within reservoir226.

Referring toFIG. 8C, a clinician may attach a needle assembly240to the tubular body212to dispense the contents of reservoir226via the needle assembly240. In one embodiment, a double-sided needle hub assembly240(as shown inFIG. 8C) is mounted on the top end214of tubular body212such that a proximal end of a needle242of needle assembly240penetrates septum218. A distal end of needle242of needle assembly240may be blunted. Furthermore, during the dispensing of the contents of reservoir226via needle assembly240by a clinician, plunger head222may be movable along the longitudinal axis “X” beyond the first retaining structure224ato a third position adjacent a neck portion214aof the tubular body212. The configuration shown inFIGS. 8A-8Callows a clinician to dispense a positive sample from reservoir226to a desired location, thus resulting in elimination of the use of a transfer syringe and a syringe needle, reducing the risk of accidental needle sticks.