Treating the killer infection known as TB

Both MDR-TB and XDR-TB patients have to undergo a more intensive, longer-lasting and more expensive treatment regimen, which also comes with more significant side effects, compared to the normal TB treatment. — MSF filepic

Tuberculosis (TB) remains a persistent global health challenge, especially in low- and middle-income countries.

Poverty, overcrowding and limited access to healthcare create an environment that facilitates its continued spread.

According to the World Health Organization (WHO), an estimated 10 million people fell ill with TB in 2022, with over 1.5 million deaths, making it one of the leading infectious disease killers globally.

What is TB?

TB is an infectious disease caused by the bacterium Mycobacterium tuberculosis.

It spreads through the air and can infect anyone exposed to the bacteria.

However, certain groups are at a higher risk of contracting and developing TB, including:

• People living with HIV (human immunodeficiency virus)
• Drug users who share needles
• Individuals with weakened immune systems, such as those undergoing chemotherapy or taking steroids, malnourished individuals, and diabetes patients
• Organ transplant recipients who take anti-rejection medications
• Infants and children aged five years and below.

While it primarily targets the lungs (commonly known as pulmonary TB), TB can also spread to other organs, resulting in extrapulmonary TB.

In children, particularly those under the age of five years, the infection can spread and result in severe forms of TB, such as TB meningitis or simultaneous infection of multiple organs such as the lungs, brain and abdomen.

Unlike adults, who typically experience TB infections confined to the lungs, this severe childhood TB can lead to death and long-term disabilities.

The classic symptoms of pulmonary TB include a persistent cough lasting more than three weeks, chest pain, fever, night sweats, unexplained weight loss and fatigue.

In extrapulmonary TB, the symptoms depend on the organs involved, which could include swollen lymph nodes, bone pain, or neurological symptoms in cases of TB meningitis.

TB treatment

The treatment of TB involves a combination of several antibiotics. 

These are aimed at reducing the risk of transmission, preventing relapse and lowering the likelihood of TB-related death.

The standard anti-TB regimen recommended by the WHO consists of:

• A two-month (eight weeks) intensive phase with isoniazid, rifampicin, pyrazinamide and ethambutol, followed by
• A four-month (18 weeks) continuation phase with isoniazid and rifampicin.

Anti-TB medicines belong to the antibiotic group.

Each medicine has a different mechanism of action, mode of administration, and side effects.

> Isoniazid

This medicine should be taken on an empty stomach (one hour before, or two hours after, meals).

Common side effects include fatigue and nausea.

It may also cause numbness in the hands and feet.

Therefore, patients are also prescribed pyridoxine (vitamin B6) to counteract this side effect.

> Rifampicin

This medicine should be taken on an empty stomach, with a full glass of water.

Its side effects include discolouration of the patient’s saliva, sweat, tears and urine, turning them reddish-orange.

However, this effect is harmless and temporary, occurring only while the patient is taking rifampicin.

> Ethambutol

This medication can be taken with food to reduce stomach-related side effects.

If serious side effects occur, e.g. vision disturbances that affect daily activities, patients should seek medical attention immediately.

> Pyrazinamide

This medicine should be taken with, or immediately after, food.

Possible side effects include fatigue, nausea, rashes and joint pain.

There is also a single tablet that has been formulated to combine all four of the above anti-TB medicines.

This combination is known as the Fixed-Dose Combination (FDC) and is typically prescribed during the intensive treatment phase.

The FDC tablet helps reduce the number of pills a patient needs to take, thereby improving adherence to treatment.

Adherence to medicines

Adherence to the anti-TB regimen is critical for curing the disease and preventing resistance.

According to the WHO, adherence to TB treatment refers to how closely a patient follows their prescribed medicines regimen.

Despite the availability of effective treatment, poor adherence remains a major barrier to global TB control efforts.

Lack of adherence has given rise to drug-resistant strains of TB, such as multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB).

MDR-TB resists isoniazid and rifampin at the minimum, while XDR-TB is even more formidable, as it demonstrates additional resistance to other antibiotics, such as fluoroquinolones, which are second-line TB medications.

These resistant variants are a growing concern as they not only complicate treatment, but also require more intensive management.

The standard six-month regimen is ineffective, necessitating prolonged courses of second- line medicines that may last between nine and 24 months, depending on the extent of resistance and patient response.

Additionally, these treatments are often more expensive, come with significant side effects, and require careful monitoring by healthcare providers, leading to higher overall healthcare costs.

There are several factors that contribute to non-compliance to medication among patients.

One of the foremost factors is access to anti-TB medicines.

In rural areas, some patients have to travel long distances to reach healthcare providers, which leads to delays or discontinuation of treatment.

The Health Ministry has implemented the Directly Observed Treatment (DOT) method to assist patients in obtaining their medicines.

This approach involves the daily supervision of anti-TB medicines intake by healthcare personnel or trained family members throughout the intensive treatment phase.

Additionally, mobile health units assist in delivering medicines directly to communities, ensuring continuity of care.

Advice to patients

An untreated TB patient can transmit the disease to 10 to 15 individuals within a year.

If diagnosed with TB, patients should always practise proper coughing and sneezing etiquette, such as covering their mouth when coughing or sneezing.

Afterward, they should wash their hands thoroughly with soap and water.

Patients are also advised to wear a face mask to reduce the risk of infecting others, and to avoid crowded or high-traffic areas.

Patients should not stop taking their medication without a doctor’s instruction, even if they start feeling better after a few weeks of treatment.

Non-adherence increases the risk of resistant TB, such as MDR-TB and XDR-TB, making future treatment more challenging.

For any inquiries regarding medicines, please call the National Pharmacy Call Centre (NPCC) at the toll-free number 1-800-88-6722 during weekdays from 8am to 5pm, except on public holidays.

Audrey Lim Huili is a pharmacist at the Health Ministry’s Institute of Clinical Research. This article is courtesy of the Health Ministry’s Pharmacy Practice and Development Division. For more information, email [e-mail]. The information provided is for educational and communication purposes only, and should not be considered as medical advice. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this article. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.