Fighting tuberculosis with the new MTB Strip Test Kit

Lecturers of the Faculty of Allied Health Sciences, Chulalongkorn University have developed MTB Strip Test Kit for Tuberculosis (TB) diagnosis that's accurate and easy to use, guaranteed by the 2023 Invention Award from the National Research Council of Thailand (NRCT) -; Another hope to reduce the spread of tuberculosis in Thailand.

Tuberculosis is one of the most contagious diseases that continues to challenge the public health system today. Although the World Health Organization (WHO) aims for 2035 (the next 12 years) to be the year to end the global tuberculosis crisis, the disease trend is still worrisome.

Thailand is one of the 14 countries with the most severe TB incidence. Fortunately, drug-resistant tuberculosis in Thailand has been removed from the WHO's list of highest-incidence countries. Only ordinary tuberculosis cases remain."

Dr. Panan Ratthawongjirakul, Associate Professor, Department of Transfusion Medicine, Faculty of Allied Health Sciences, Chulalongkorn University

Tuberculosis is an airborne disease caused by a bacterium called "Mycobacterium tuberculosis". It is spread from TB patients to others through small respiratory secretions (AKA droplets) that come from coughing, sneezing, or talking. It is easy to contract and it spreads quickly.

"One of the mechanisms to help end tuberculosis is identifying TB patients as early as possible to control and limit its transmission" said Assoc. Prof. Dr. Panan about the inception of the research project to develop MTB Strip (Mycobacterium tuberculosis Strip) that is easy to use, convenient to read by the naked eye, and with fast and accurate results. More importantly, the cost should not be high to make it accessible to local public health service systems.

"If we can distribute this test to small hospitals everywhere, we will be able to identify TB patients within two hours and screen positive patients quickly into the treatment system. We believe this will help reduce the number of TB cases in our country" said Assoc. Prof. Dr. Panan about the objective of MTB Strip innovation.

Pros and Cons of the current methods of TB Testing

Assoc. Prof. Dr. Panan mentioned the various advantages and disadvantages of current testing methods for tuberculosis as follows:

1. Microscopic examination using acid-fast staining is a simple method. It can be done in a small hospital, but the disadvantage is low sensitivity (the minimum bacterial concentration required for a positive signal when examining with a microscopic examination is 5000–10000 cells in 1 ml of sputum.
2. Sputum culture is the standard method of diagnosing tuberculosis, but it can only be done in well-equipped large hospitals. This method must be done in a room with a high-safety system to prevent it from spreading outside. It takes more than a month to know the results which will result in delayed treatment.
3. TB Genotyping involves taking the patient's sputum to extract and amplify the genetic materials which are then tested by a Real-time PCR machine. The disadvantage of this method is that it is costly and requires a lab with specialized personnel, so it can be done only in some hospitals.

Based on the advantages and limitations of various methods used to detect tuberculosis, the research team developed the MTB Strip Test Kit.

Faster and easier TB Screening with MTB Strip

MTB Strip TB Test Kit consists of 2 main parts: 1. Genetic amplification using isothermal amplification with specifically modified and designed primers. 2. Genetic materials detection using developed test strips, which are manufactured from ISO13485-certified industrial plants for medical device manufacturing.

Assoc. Prof. Dr. Panan explained the process of using this test kit "after receiving sputum from the patient, the DNA will be extracted and used as a template. We will put a primer specially designed to amplify the amount of genetic material in the DNA of the pathogen in the patient's sputum before entering the isothermal amplification process by using a recombinase polymerase amplification technique. It takes only 20 – 40 minutes at 37 degrees Celsius. Then, the developed test strip is dipped into the amplified genetic material. The results will appear on the test strip as positive and negative results like the ATK test that we are familiar with."

The key feature of the MTB Strip is its sensitivity to tuberculosis. With a small amount of tuberculosis in the sputum, the test can detect it and display the result. In addition, the test process takes less than an hour and does not require any special tools.

"The results are up to 96 percent accurate compared to Realtime PCR and other commonly used acid-resistant dye methods. Importantly, this kit is cheaper than molecular biology tests because it does not require any special tools such as thermocycler" Assoc. Prof. Dr. Panan emphasized.

The MTB Strip kit uses the principle of amplifying genetic material under a single constant temperature in conjunction with a heat box. In a typical laboratory, this type of box is already available. Small hospitals can also use this technique.

"The MTB Strip TB test kit we have developed will enable many existing small and medium-sized hospitals in Thailand to screen for TB cases so that patients can receive appropriate treatment quickly, thereby reducing the number of TB cases and the spread of TB."

Fighting tuberculosis with the Distribution of MTB strips to the provinces

The MTB Strip Test prototypes have already been administered at Umphang Hospital, Tak Province in 2019-2020 and the results are good to a certain extent. However, Assoc. Prof. Dr. Panan has not stopped developing methods and innovations to reduce the number of cases of tuberculosis in Thailand.

"Although the MTB Strip kit works satisfactorily, we would still like to develop more sensitivity by making the DNA extraction easier to be used as the kit primer."

In addition, Assoc. Prof. Dr. Panan also has plans to expand the testing of TB and related diseases by developing an easier-to-use DNA extraction kit and TB test kit that can identify drug-resistant variants of TB right from the outset, so that more specific treatment guidelines can be set.

"We are currently conducting in-depth research on the genetic modification of tuberculosis using a novel technique of genetic modification for a living organism called CRISPR Cas-9 Interference to modify certain TB genes, making the infection less aggressive and more responsive to antituberculosis drugs. CRISPR Cas-9 Interference can be used in conjunction with current antituberculosis drugs."

If the study is successful, it will be a new TB treatment of the future, which Assoc. Prof. Dr. Panan is sure will help reduce the number of TB cases to reach WHO's target. Small hospitals interested in the MTB Strip Test kits can contact Assoc. Prof. Dr. Panan Rathwongjirakul, the Research Unit of Innovative Diagnosis of Antimicrobial Resistance, Department of Transfusion Medicine and Clinical Microbiology, Faculty of Allied Health Sciences, Chulalongkorn University.