Revisiting tuberculosis

Professor Dr James Koh, head of the Division of Medicine, School of Medicine, International Medical University, gives a refresher on tuberculosis (TB) and reminds HCPs to always be on the lookout for the disease.

Mycobacterium tuberculosis is the bacteria that lends its name to TB. The pathogenic bacteria belong to the family Mycobacteriaceae and is unique in that it has a waxy coating on its cell surface that is composed of mycolic acids, which are long-chain fatty acids. [Available at https://www.cdc.gov/tb/topic/basics/default.htm #:~:text=Tuberculosis%20(TB)%20is%20caused%20by,with%20TB%20bacteria%20becomes%20sick Accessed on 13 April 2023] This fatty acid component of their cell wall is what makes the bacteria neither Gram-positive nor Gram-negative. The same fatty acids also make them less susceptible to antibiotics and escape the human immune system. [eLife 2015;4:e08525]

TB can attack various parts of the body, with the most common being pulmonary tuberculosis (PTB), which affects the lungs. Extrapulmonary tuberculosis (EPTB) is a term used to classify TB when it manifests in locations other than the lungs, such as the lymph nodes, bones (usually the spine), and, in rare cases, the gut. In immunocompromised patients, such as those with HIV, the virus can attack the brain.

The bacterium is airborne, therefore it is unlikely to spread via shaking of hands; sharing of food or drinks; touching bed sheets or toilet seats, or kissing. It usually requires prolonged exposure for someone with TB to spread it. Thus, those likely to be infected are family members, friends, colleagues, and schoolmates. Those who are most susceptible to the infection are the elderly, people with compromised immunity, such as diabetics, those with immunosuppression, such as those on chronic steroid therapy, and HIV-positive individuals. These include persons with medical conditions that weaken the immune system such as those with organ transplants, cancer, and substance abuse. Young children are also at greater risk because their immune systems are still developing, which is why the BCG vaccine is administered to them. Migrant workers and the poor, who are often subjected to overcrowded and unsanitary conditions, are also at high risk of contracting TB. [Risk Manag Healthc Policy 2021;14:2965–2970]

The four cardinals
PTB is characterized by four clinical symptoms, which are persistent cough, profuse night sweats, weight loss, and recurrent rise in evening body temperature. In EPTB manifestations, the disease manifests as swollen lymph nodes, chronic back pain, fragile bones, a sensitive gut, and seizures, headaches, confusion, and even personality changes if it affects the brain.

One of the challenges in detecting tuberculosis is that it does not manifest symptoms immediately. One may have been exposed many years ago, and the bacteria will remain latent or dormant in the body. According to Koh, symptoms may manifest months or even years after the initial exposure. In addition, the gradual and subtle onset of the symptoms is unlikely to cause concern until the disease has advanced, such as when one begins coughing up blood.

TB confirmation
TB is diagnosed via a series of tests. Lung X-rays for PTB will reveal “cavities,” a tell-tale sign of tuberculosis. This will warrant further tests such as a saliva or sputum test and a tuberculin skin test; in cases of EPTB, a bone or swelling biopsy may be required.

As a general rule, patients should be encouraged to consult a doctor if they have had a cough for 2 weeks. It should then be determined whether to perform a tuberculosis test based on the patient’s detailed medical history and overall health.

Those living or working in proximity to confirmed TB patients should also get screened for TB. Malaysia has a good notification system in place where, once a person is tested positive for TB, the doctor in charge will notify a public health officer, who will then initiate contact tracing to identify those who are possibly exposed and subsequently test them.

Treatment
Treatment for tuberculosis is a fairly straightforward but lengthy process. Depending on the affected body part, a combination of four antibiotics will be prescribed for anywhere between 6 months and 1 year.

“For PTB, it is generally within 6 months. EPTB needs 9 to 12 months,” said Koh. “Newer medications can potentially treat TB within 3 months, but Malaysia does not have the facility yet. At the moment, we’re still using the old regimen.”

It is essential to stress to patients that they must take their medications as prescribed and on time. If a patient does not complete the course of treatment or misses doses, they should understand that the bacteria may develop resistance to the medication. The bacteria may evolve into superbugs such as extensively drug-resistant tuberculosis (XDR TB) and multidrug-resistant tuberculosis (MDR TB).

“Those with MDR/XDR TB can spread it to others, and unfortunately for that someone, because the bacteria is already resistant, it becomes very hard to treat. These cases will need a lot of alternative medications involving injections and much longer therapy for up to 2 years. It gets very, very complicated,” said Koh. To prevent such lapses, the public health system employs a check-in protocol in which patients undergoing treatment are routinely monitored to ensure that the drugs are administered correctly.

After 10 to 14 days following the initiation of treatment, the individual will no longer be infectious. In a hospital setting, TB patients will be placed in isolation, but there is no set prescribed quarantine period. In these cases, it is important to get the patient to wear a mask and wash their hands regularly, said Koh.

Takeaway tips
A healthy lifestyle is the most effective means of preventing TB. A healthy individual with a strong immune system should be able to fight off tuberculosis on their own. Koh said it is important to be aware of the symptoms of TB, as early treatment is essential. If left untreated for too long, TB can permanently reduce a person’s lung capacity by scarring the lungs, even after recovery. “When a person has recovered, maintain a good diet, exercise, and don’t smoke. One can get re-infected with TB and that can be quite bad.” 

The stigma that those with TB experience is a serious issue. To avoid this problem, education about the disease is necessary. Koh said TB is still commonly viewed as a “dirty disease” and a death sentence, a perception that may not have been helped by the portrayal of the disease in films. It is far from this, and this misconception can delay treatment due to feelings of helplessness, fear of isolation, and social rejection. The disease is treatable and can affect anyone.