New Methods Revolutionize Detection of Tuberculosis
등록일 2019년 01월 07일 화요일
수정일 2017년 11월 07일 화요일

Photo via Pixnio

Researchers at the Arizona State University developed a new method to quickly and accurately detect tuberculosis in people.This new approach helps in TB diagnosis among HIV-positive individuals.

One of the new methods developed by the researchers measures the proteins produced by TB bacteria in the blood during active infections.The technique can detect all forms of TB in patients, including TB in HIV-positive patients, which a standard bacteria culture test fails to do.The second method uses nanotechnology for areas with limited resources because it only requires little equipment and supplies that can be read by a mobile phone.

Standard diagnostic methods to test TB suffer from several drawbacks, especially in areas where resources are limited.

1.TB skin tests detect the presence of TB bacteria in a person.But TB skin tests fail to determine if the infection is still present and whether the bacteria is active or dormant.

2.The culture of TB bacteria from patient samples require four to six weeks before providing results.

3.A sputum sample or respiratory tract mucus is usually needed for TB tests.But invasive procedures may be performed if the patient cannot provide enough sputum.

4.If the concentration of TB bacteria in samples is low, standard detection methods often fail.

The two methods used porous silica nanodisks graced with antibodies to the TB proteins CFP-10 and ESACT-6 produced by bacteria in the bloodstream.

"Our goal is the diagnosis of all forms of TB.We're targeting pulmonary, extra-pulmonary, culture positive, culture negative, adult and pediatric, HIV or no HIV.As long as you have bacteria in the body, we can capture it," said Tony Hu, a researcher at the Biodesign Institute at the Arizona State University.

The research team also used a similar approach to detect factors in blood to help identify people called HIV elite controllers.These people have the rare ability to suppress HIV without the assistance of antiretroviral drug therapy.

Tuberculosis and HIV

Tuberculosis is a contagious respiratory infection caused by the bacteria called Mycobacterium tuberculosis.The infectious agent primarily attacks the lungs but can damage other parts of the body as well.TB is airborne and an infected person spreads it by coughing, sneezing, or simply talking to another person.The risk of TB infection increases significantly if the person has a compromised or weakened immune system, such as people with HIV.

Symptoms associated with TB include a bad cough that lasts for three weeks or longer, weight loss, appetite loss, coughing up blood and mucus, fatigue, fever, and night sweats.The effectiveness of TB medications depends on how early the infection was diagnosed and the strength of the person's immune system.

Because HIV can weaken a person's immune system, TB bacteria multiply faster and cause active TB infection.A person infected with both TB and HIV is at least ten times more likely to develop an active TB.Also, a person infected by both indicates the advanced stage of HIV called AIDS, acquired immune deficiency syndrome.

Treatment for Tuberculosis

Whether the TB is active or dormant, the person must be treated immediately.For dormant TB, a clinician will prescribe isoniazid and pyridoxine, a form of vitamin B6 to avoid nerve damage of the hands and feet, for 6 to 12 months.If isoniazid is ineffective, the clinician may switch to rifampin.For active TB, a clinician will prescribe a combination of drugs that include ethambutol, isoniazid, pyrazinamide, and rifampin, and must be taken religiously for several months.

Unfortunately, TB medication conflicts with HIV drugs and the doctor will combine the right drugs that suit the patient.If the CD4 count is not yet low, the doctor will immediately start the patient on tuberculosis medication.But if the patient already started with ART, the doctor needs to adjust the treatment to address both diseases.

Photo via Pixnio

Facts About Tuberculosis

- An estimate of 33 percent of the global population may have dormant TB with five to ten percent change to become active.

- TB was responsible for the 1.8 million deaths in the year 2015 and 1.7 million deaths in 2016.The disease remains among the top ten causes of worldwide death.

- More than 95 percent of TB deaths occur in low-income and middle-income countries.

- Some TB bacteria are resistant to drugs.These strains are resistant to isoniazid and rifampin.

- About 35 percent of HIV patients die from TB infections in the US, and about 75 percent in Africa and South Asia.

- Compared with healthy people, people with HIV are 20 to 30 times more susceptible to TB infection.People infected with TB are more vulnerable to HIV infection.TB is the leading cause of deaths in HIV patients.

- Some HIV-positive patients have undiagnosed TB infection because TB symptoms can mirror complications of HIV and standard TB tests are less sensitive to people with HIV.

- The TB rate in Asians is at least 18.2 cases per 100,000 persons while in Hispanics or Latinos, it is at least 4.8 cases per 100,000 persons.

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