WO2026009038A1

WO2026009038A1 - Bacterial diagnostic device

Info

Publication number: WO2026009038A1
Application number: PCT/IB2025/050907
Authority: WO
Inventors: Amanda SKEPU; Eldas MAESELA; Manfred Rudolf SCRIBA; Martin Brian WILLIAMS; Masibulele Timothy KAKAZA; Yolandy LEMMER
Original assignee: CSIR
Current assignee: CSIR
Priority date: 2024-07-05
Filing date: 2025-01-28
Publication date: 2026-01-08
Anticipated expiration: 2027-01-05

Abstract

An E. coli bacterial diagnostic device comprises an outer body with a first chamber for fluid intake and a second chamber for a lateral flow test strip holder, featuring a results viewing window. An inner body, rotatable within the first chamber, includes a fluid receiving chamber and an opening for fluid passage. A filter located between the outer and inner bodies ensures fluid filtration. A lateral test strip holder, located in the second chamber, can move between a test position in which a portion of a lateral flow test strip located in the lateral test strip holder is positioned in the first chamber adjacent the filter and a second retracted position in which the lateral flow test strip is positioned in the second chamber.

Description

BACTERIAL DIAGNOSTIC DEVICE

BACKGROUND OF THE INVENTION

A bacterial diagnostic device is provided, particularly for use in detecting E. coli.

Water resources free of bacteria are important for human and animal use primarily because bacteria in water can cause various diseases and infections. Ensuring water resources are free of bacteria is thus essential for protecting public health, promoting hygiene practices, supporting agriculture, safeguarding animal health, preserving the environment, and reducing economic burdens associated with waterborne diseases. Bacteria such as Escherichia coli (E. coli), are commonly found in contaminated water sources. Consuming water contaminated with these bacteria can lead to gastrointestinal illnesses such as diarrhoea, abdominal pain, nausea, and vomiting. These symptoms can range from mild to severe, depending on the strain and the individual’s health status. Certain strains of E. coli, such as E. coli 0157, produce toxins (Shiga toxins) that can lead to a serious complication known as HUS. This condition can cause kidney failure, particularly in young children and the elderly.

Animals also require clean water for drinking and hygiene purposes. Contaminated water sources can lead to diseases in livestock, affecting their health, growth, and productivity. Clean water is crucial for agricultural activities, including irrigation and livestock farming. Using contaminated water for irrigation can lead to the contamination of crops, potentially causing foodborne illnesses in humans and animals. Furthermore, these waterborne diseases impose significant economic costs due to medical treatment expenses, lost productivity, and the burden on healthcare systems. Access to clean water reduces these costs by preventing illnesses. It is thus crucial that all entities that release effluent water into rivers, oceans or wetlands, or recycle water, ensure proper treatment of such water to make sure that it complies to acceptable levels of bacteria such as E. coli. The effluent water can be wastewater from industrial, commercial, or domestic sources. Many countries thus have strict regulations governing the discharge of effluent water into the environment. T reatment ensures that effluent meets these regulatory standards, avoiding fines and legal penalties for non- compliance.

To mitigate health risks, it is crucial to ensure that water sources are properly monitored, treated, and maintained to prevent contamination with pathogenic E. coli and other harmful bacteria. Public health interventions such as water quality testing, sanitation improvements, and education on safe water practices are essential for reducing the health impacts of E. coli contamination in water.

To ensure that levels of E. coli in treated and other water sources are acceptable, several key steps are typically employed. Governments and health authorities set specific water quality standards and guidelines that dictate acceptable levels of E. coli and other microbial contaminants in drinking water, recreational water, and other water sources. These standards are based on health risk assessments and are regularly updated as per scientific advancements. Regular and systematic monitoring of water quality is crucial. Water utilities and regulatory agencies collect samples from various points in the water distribution system, treatment plants, recreational water bodies (like beaches and lakes), and drinking water sources. These samples are tested for the presence and concentration of E. coli and other indicator organisms.

These tests may include culture-based methods to detect and quantify E. coli colonies, as well as molecular techniques like PCR (Polymerase Chain Reaction) for rapid detection of specific genetic markers. One approach follows the ISO 9308-1 :2014 international standard titled "Water quality - Enumeration of Escherichia coli and coliform bacteria -- Part 1 : Membrane filtration method for waters with low bacterial background flora." This standard provides guidelines and procedures for testing water samples to enumerate Escherichia coli (E. coli) bacteria using the membrane filtration method.

ISO 9308-1 :2014 is used for testing water for E. coli by passing 100ml of water through a membrane filter with a pore size that retains bacteria then placing the filter on a selective agar medium (such as m-Endo agar or Chromocult agar) that supports the growth of E. coli while inhibiting the growth of other bacteria.

The plates are then incubated at a specified temperature (usually 35-37°C) for a defined period (typically 18-24 hours) to allow colonies of E. coli to develop. A procedure is then followed for counting the colonies of E. coli that appear on the membrane filter. Results are expressed as colony forming units (CFUs).

Other methods of determining the presence of E. coli in water samples include Polymerase Chain Reaction (PCR) where the specific Deoxyribonucleic acid (DNA) sequences of E. coli are amplified for low concentration detection. The method can quantify the E. coli concentration and requires specialized equipment and is expensive.

Biosensors use antibodies or DNA probes to bind to E. coli. The binding triggers a signal, often electrical or optical to indicate the presence of the bacteria. It allows for real-time monitoring but is low sensitivity and is prone to interference.

Colorimetric Detection relies on bio-chemical colour change in the presence of specific substrates or reagents such as E. coli bacteria. The approach requires the filling of tubes and adding of reagents with mixing or shaking steps and may include incubation. It is simple and cost-effective but lacks sensitivity and is semi quantitative at best. In all these tests, multiple steps are required including the handling of samples, tubes and reagents and are thus best performed in a laboratory. In addition, the time required to acquire a result can be as long as 24 hours.

A test approach that delivers rapid results, is simple to use, portable, and suitable for on-site testing is thus highly desirable.

The present invention seeks to addresses this.

SUMMARY OF THE INVENTION

According to a first example embodiment there is provided a bacterial diagnostic device including: an outer body having a first chamber therein and a fluid receiving opening via which fluid can pass into the first chamber, the outer body further including a second chamber sized to receive a lateral flow test strip holder, the outer body further including a results viewing window through which results displayed on a lateral flow test strip located in the second chamber can be viewed; an inner body sized to be located in the first chamber of the outer body and to be rotatable with respect to the outer body between first and second positions, the inner body having a fluid receiving chamber therein, the inner body further having an opening therein so that fluid can pass via the opening from the fluid receiving opening into the fluid receiving chamber; a water filter sheet sized to be located between the outer body and the inner body so that fluids passing from the fluid receiving opening and into the fluid receiving chamber will first pass through the filter, the filter having pores sizes as to establish a filtration efficiency to retain particles such as E. coli bacteria from the fluids; and a lateral test strip holder sized to be located in the second chamber and being movable in the second chamber between a first test position in which a portion of a lateral flow test strip located in the lateral test strip holder is positioned in the first chamber adjacent the filter and a second retracted position in which the lateral flow test strip is positioned in the second chamber.

The outer body preferably includes an elongate cutout in a wall of the outer body and the inner body has a lug extending from a wall of the inner body, the lug being sized to fit into the elongate cutout and to move along the elongate cutout when the inner body is rotated with respect to the outer body.

The elongate cutout is preferably shaped so that when the inner body is rotated with respect to the outer body between the first position and the second position, the lug travels along the elongate cutout and moves the inner body and filter away from the outer body so that a space is created between the filter and outer body into which a lateral test strip can be inserted.

The inner body may further include a filter holding rim to receive and hold the filter in use in position between the inner body and the outer body, the filter holding rim having a portion of the rim cut away so that a lateral flow test strip can pass through the filter holding rim to contact the filter.

In one example, when the inner body is in the first position, the cut away portion of the filter holding rim is not aligned with the second chamber and so a lateral flow test strip located in the lateral test strip holder cannot be moved into the first chamber adjacent the filter, and neither can the water reach the lateral flow strip, and when the inner body is in the second position, the cut away portion of the filter holding rim is aligned with the second chamber and so a lateral flow test strip located in the lateral test strip holder can be moved into the first chamber adjacent the filter. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a bacterial diagnostic device according to an example embodiment of the present invention;

Figure 2 shows the bacterial diagnostic device of Figure 1 with a water release container, with the water to be tested being inserted into the device;

Figure 3 is an exploded view of the bacterial diagnostic device of Figure 1 ;

Figure 4 shows a partially cut away view of the device with a lateral test strip holder located in a second chamber in a second retracted position;

Figure 5 shows a partially cut away view of the device with the lateral test strip holder located in the second chamber in first test position;

Figure 6 shows various combinations of test results using a control line and a test line.

DESCRIPTION OF EMBODIMENTS

The present invention relates generally to abacterial diagnostic device. It will be appreciated that whilst the description below will refer to testing for E. coli, the device could be used for the detection of a wide range of waterborne pathogens.

Referring to Figure 1 of the accompanying drawings, an E. coli bacterial diagnostic device includes an outer body 10 having a first chamber 12 therein and a fluid receiving opening 14 via which fluid can pass into the first chamber 12. The outer body 10 further includes a second chamber 16 sized to receive a lateral flow test strip holder 18.

The outer body 10 further includes a results viewing window 20 through which results displayed on a lateral flow test strip 22 located in the second chamber 16 can be viewed.

An inner body 24 is sized to be located in the first chamber 12 of the outer body 10 and to be rotatable with respect to the outer body 10 between first and second positions.

The inner body 24 has a fluid receiving chamber therein and has one or more openings 26 therein so that fluid can pass from the fluid receiving opening 14 into the fluid receiving chamber.

In the illustrated embodiment, the inner body 24 has multiple openings 26.

A filter 28, typically in the form of filter paper, is sized to be located between the outer body 10 and the inner body 24 so that fluids passing from the fluid receiving opening 14 and into the fluid receiving chamber will first pass through the filter 28.

The filter 28 has a filtration efficiency to remove particles from the fluids.

The filtration efficiency is according to ISO 9308-1 :2014 used for testing water for E. coli in terms of which a pore size of the filter 28 is such that it retains E. coli bacteria found in the water.

Lateral test strip holder 18 is sized to be located in the second chamber 16 and is movable in the second chamber 16 between a first test position and a second retracted position.

In the first test position, a portion of a lateral flow test strip 22 held by the lateral test strip holder 18 is positioned in the first chamber 12 adjacent the filter 28 and in the second retracted position the lateral flow test strip is positioned in the second chamber away from the filter 28.

An O-ring 30 is used to create a seal around the filter 28.

The outer body 10 additionally has an elongate cut out 32 in a wall of the outer body 10 and the inner body 24 has a lug 34 extending from a wall of the inner body 24.

The lug 34 is sized to fit into the elongate cut out 32 and to move along the elongate cut out 32 when the inner body 24 is rotated with respect to the outer body 10.

The elongate cut out 32 is shaped so that when the inner body 24 is rotated with respect to the outer body 10 between the first position and the second position, the lug 34 travels along the elongate cut out 32 and moves the inner body 24 and filter 28 away from the outer body 10 so that a space is created between the filter 28 and outer body 10 into which a lateral test strip 22 can be inserted. This will be explained in more detail below.

The inner body 24 further includes a filter holding rim 36 to receive and hold the filter 28 in use in position between the inner body 10 and the outer body 24.

The filter holding rim 36 has a portion of the rim cut away 38 so that a lateral flow test strip can pass through the filter holding rim to contact the filter.

When the inner body 24 is in the first position, the cut away portion 38 of the filter holding rim 36 is not aligned with the second chamber 16 and so a lateral flow test strip 22 located in the lateral test strip holder 18 cannot be moved into the first chamber 12 adjacent the filter 28.

When the inner body 24 is in the second position, the cut away portion 38 of the filter holding rim 36 is aligned with the second chamber 16 and so a lateral flow test strip 22 located in the lateral test strip holder 18 can be moved into the first chamber adjacent the filter.

The lateral flow test strip holder 18 includes a small handle 40 by means of which the lateral flow test strip holder 18 is movable into the second chamber 16 between the first test position and second retracted positions.

The outer body 10 further has a sliding window 42 in which the small handle 40 is able to slide up and down to move the lateral flow test strip holder 18 inside the second chamber 16.

A cover 44 is connectable to the outer body 10 to cover the second chamber 16.

It will be appreciated that when the device is put together it is a handheld device which can easily be used as follows.

In use, the device is assembled with the filter 28 and the O-ring 30 being placed in the filter holding rim 36 of the inner body 34.

The inner body 34 is then inserted into the first chamber 12 in the first position, with the lug 34 located in the first position in the cut out 32, as illustrated in Figure 1 .

The lateral flow test strip 22 is placed in the lateral test strip holder 18 and together these are inserted into the second chamber 16.

The cover 44 is now connected to the outer body 10 to cover the second chamber 16 and the assembled device is now ready to use.

100ml of water to be tested is collected in a sterile syringe 46 and emptied into the device through the fluid receiving opening 14, as illustrated in Figure 2. It will be appreciated that the water injected will pass through the filter paper 28 into the fluid receiving chamber 34 of the inner body 24, leaving E. Coli bacteria on the surface of the filter paper 28.

Next, a growth medium to facilitate the growth of E. coli is injected into the device through the fluid receiving opening 14.

The growth medium will provide the means for the E. Coli bacteria on the surface of the filter paper 28 to multiply.

The device will now be inserted into an environmentally controlled chamber for 1 to 6 hours where it will typically be subject to heat. This will cause the E. Coli bacteria to grow on the filter paper 28 in the presence of the growth medium.

The device is then removed from the environmentally controlled chamber and the inner body 24 is rotated by 30 degrees with respect to the outer bodyl O.

This will cause the lug 34 to travel along the cut out 32 thereby forcing the lug 34 and in turn the inner body 24 and filter paper 28 away from the inner surface of the outer body 10. This leaves a space between the filter paper 28 and outer body 10 inside the first chamber into which a lateral test strip can be inserted. This can be seen in Figure 4.

The lateral test strip holder 18 is now moved from a second retracted position towards the first test position in which a portion of the lateral flow test strip 22 located in the lateral test strip holder is positioned in the first chamber adjacent the filter paper 28 and is in contact with the filter paper 28. This can be seen in Figure 5.

The user will now wait 2 minutes and read the result on the lateral flow test strip 22 via the results window 20. The result on the lateral flow test strip 22 will take the typical format of having a control line and a test line. A positive test result requires both the control line and the test line to be positively activated and visible. If only the control line is positively activated and visible, but the test line is not, then the result is negative.

If the control line is not positively activated and visible, then the test is flawed, and the result can be rejected.

Alternatively, or in addition, the lateral flow test strip 22 is provided with electronic sensor means including a digital readout.

The electronic sensor means measure the density of the test and control line on the lateral flow strip 22 and the result is displayed to the user on the digital readout via a display on the device.

It will be appreciated that the all-in-one design reduces the complexity of the testing process, making it more user-friendly. This is particularly beneficial for field testing or in resource-limited settings where specialized training and equipment are not readily available.

Users can perform the test with minimal training, as the device simplifies the handling and procedural steps. Combining all necessary steps into one device can significantly reduce the overall time required for detection.

Traditional methods might take 24-48 hours for results due to separate incubation and testing phases, while the current device can provide results in between 1 and 6 hours depending on the detection limit required.

The device's all-in-one nature makes it portable and convenient for on-site testing. This is a significant advantage over lab-based solutions that require transporting samples to a central facility. By eliminating the need for multiple pieces of equipment and reducing the complexity of the process, the device can perform tests at a lower overall cost.

Furthermore, the device allows for a variation in incubation time thus allowing a selective detection pf E. coli levels between 100 and 1000 CFU. This is particularly useful for regulatory compliance and public health, as it provides a clear and actionable result without requiring detailed quantification.

The integrated approach uses fewer resources, such as reagents and materials, which contribute to cost savings, and in addition the device's simplicity and ease of use make it accessible to a broader range of users, including those in developing countries or areas without advanced laboratory facilities.

Claims

1 . A bacterial diagnostic device includes: an outer body having a first chamber therein and a fluid receiving opening via which fluid can pass into the first chamber, the outer body further including a second chamber sized to receive a lateral flow test strip holder, the outer body further including a results viewing window through which results displayed on a lateral flow test strip located in the second chamber can be viewed; an inner body sized to be located in the first chamber of the outer body and to be rotatable with respect to the outer body between first and second positions, the inner body having a fluid receiving chamber therein, the inner body further having an opening therein so that fluid can pass via the opening from the fluid receiving opening into the fluid receiving chamber; a filter sized to be located between the outer body and the inner body so that fluids passing from the fluid receiving opening and into the fluid receiving chamber will first pass through the filter, the filter having a filtration efficiency to remove particles from the fluids; and a lateral test strip holder sized to be located in the second chamber and being movable in the second chamber between a first test position in which a portion of a lateral flow test strip located in the lateral test strip holder is positioned in the first chamber adjacent the filter and a second retracted position in which the lateral flow test strip is positioned in the second chamber.

2. A device according to claim 1 wherein the outer body has an elongate cutout in a wall of the outer body and the inner body has a lug extending from a wall of the inner body, the lug being sized to fit into the elongate cutout and to move along the elongate cutout when the inner body is rotated with respect to the outer body.

3. A device according to claim 2 wherein the elongate cutout is shaped so that when the inner body is rotated with respect to the outer body between the first position and the second position, the lug travels along the elongate cutout and moves the inner body and filter away from the outer body so that a space is created between the filter and outer body into which a lateral test strip can be inserted.

4. A device according to any preceding claim wherein the inner body further includes a filter holding rim to receive and hold the filter in use in position between the inner body and the outer body, the filter holding rim having a portion of the rim cut away so that a lateral flow test strip can pass through the filter holding rim to contact the filter.

5. A device according to claim 4 wherein when the inner body is in the first position, the cut away portion of the filter holding rim is not aligned with the second chamber and so a lateral flow test strip located in the lateral test strip holder cannot be moved into the first chamber adjacent the filter, and when the inner body is in the second position, the cut away portion of the filter holding rim is aligned with the second chamber and so a lateral flow test strip located in the lateral test strip holder can be moved into the first chamber adjacent the filter.