Dr. Raquel Muñiz Salazar, a researcher at the School of Health Sciences of the Autonomous University of Baja California (UABC), is working on the development of a new method for diagnosing tuberculosis, which obtains results on the same day, which detects drug resistance in drugs of first and second line, and that has a lower cost than the specialized equipment that is currently used only in some public health centers.

In Mexican public health centers, the diagnostic method is by smear microscopy, which consists of collecting a daily sample of phlegm from the patient for three consecutive days to search for the presence of the Mycobacterium tuberculosis bacterium, which causes the disease. However, the World Health Organization (WHO) warns that smear microscopy “only detects half of the cases of tuberculosis and is unable to determine if there is drug resistance.”

Dr. Rafael Laniado Laborín is head of the tuberculosis clinic and laboratory of the General Hospital of Tijuana, one of the two institutions in Baja California that have specialized equipment to detect tuberculosis through molecular biology techniques.

In an interview with the Information Agency of the National Council for Science and Technology (CONACYT), Dr. Laniado explained that the equipment is only used to analyze the samples of patients suspected of being drug-resistant, due to the high costs involved in its use.

Thanks to this equipment, the clinic has the ability to perform sputum smears, liquid and solid cultures and automated molecular tests, and its use requires cartridges, similar to those of a printer, which have an automated laboratory of molecular biology and they allow knowing in a matter of hours if the person has tuberculosis, what type of strain is and if it is resistant to any of the first-line drugs, which are those that are given to patients who do not have drug resistance.

This equipment offers a rapid and effective tuberculosis test, so since 2010 the WHO recommends its use; however, due to its costs, it is not used as the routine method in public health centers.

The head of the tuberculosis clinic in Tijuana said that when tuberculosis is not detected in time, the risk is double: first for the person, because its development, morbidity and mortality increase; and second, because the patient transmits the infection in their community. It is estimated that while a patient infected with tuberculosis does not treat the disease, in a year it can infect between 10 and 15 people.

The development of the new method by Dr. Muñiz Salazar is financed with resources from the call for Attention to National Problems of CONACYT.

Tijuana’s tuberculosis clinic has specialized equipment that is used to detect drug resistance in patients,; however not all institutions have the same equipment and, so they perform other studies that involve the cultivation of the bacteria, which lasts for a period of six to eight weeks.

“It takes between six and eight weeks to know if the expectoration sample is inoculated into the culture medium. If it grows, then the patient has Mycobacterium tuberculosis, but you cannot differentiate between tuberculosis and bovis or any other species,”said Dr. Muñiz.

A second test called MGIT is the one that elaborates a profile of drug sensitivity of the patient to determine if the bacteria can be eliminated with the medications that are administered as part of the treatment.

A new method

Given these challenges, Dr. Raquel Muñiz and her colleagues try to design a test with enough effectiveness to inform the patient from the first day if the bacterium was detected, and determine if it is drug-resistant in a maximum time of one week to.

One of the most important goals of the new method is to keep it low cost, so that it does not depend on the purchase of specialized equipment. The idea is that it can be done with small equipment that is already in the laboratories of the health sector and does not imply implementation of a level three security system.

With a test of this type, the requirement to go for three days in a row to the health center in order to provide samples of expectoration would be eliminated; and a more accurate, quicker and more sensitive diagnosis will be offered.

 

Source: Agencia Informativa CONACYT