TUBERCULOSIS

                                                

Ø Tuberculosis or TB is a potentially serious infectious disease.

Ø It is caused by Bacteria called Mycobacterium Tuberculosis.

Ø TB mainly affects the Respiratory system but can affect other organ systems like Gastrointestinal system, the Lymphoreticular system, the skin, the Central nervous system, the Musculoskeletal system, Reproductive system and the liver.

Ø Tuberculosis that affects lungs is called Pulmonary tuberculosis.

Ø Tuberculosis that affects organs other than lungs is called Extrapulmonary tuberculosis.

TYPES OF TB

Latent TB

Many of those who are infected with TB bacteria do not develop disease ,the bacteria in their body are inactive that cause no symptoms and their chest X ray will be normal. Latent TB also called inactive TB, isn’t contagious. Latent TB can turn into active TB, so treatment is important in certain group of people. This latent TB only diagnosed through Tuberculin skin test or Interferon gamma release assay (IGRA).

Active TB

It is an illness in which the TB bacteria are rapidly multiplying and invading different organs of the body.

• Coughing for two or more weeks
• Expectoration
• Hemoptysis (sometimes)
• Fever – mostly low grade, evening raise of hemoptysis
• Chills
• Chestpain
• Loss of apettite
• Unintentional weight loss
• Fatigue

In case of Extrapulmonary tuberculosis, signs and symptoms vary according to the organs involved. For example, TB of the spine cause back pain and TB of the kidneys might cause blood in urine, TB of the intestine cause abdomen pain, diarrhea.

MODE OF TRANSMISSION

Tuberculosis is transmitted between person to person through air. When people with PTB cough , snneze, or spit, microscopic droplets released into air. IF the healthy people inhale only a few of these germs present in the droplets, they will get infected.

Although TB is contagious, its not easy to catch. It is much more likely to get TB from someone you live or work with than from a stranger.

Most people with Active TB who have had appropriate drug treatment for atleast two weeks are no longer contagious.

PATHOPHYSIOLOGY

                                M.Tuberculosis starts replication inside macrophages

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                                                  Primary infection occurs

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Cell mediated immunity gets activated , surrounds the cell to forms granuloma (3 weeks)

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                                  Leads to necrosis of tissues at infection site

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                                      Involve nearby lymph nodes (Gohn’s complex)

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                                    Calcification of Gohn’s complex (Latent T.B)

Incubation period:  Approximately 2 to 12 weeks. However, the risk for developing active disease is highest in the first two years after infection.

DIAGNOSIS

Physical exam

 Check  lymphnodes for swelling and use a stethoscope to listen to the sounds lungs make when breathe, patients with PTB have abnormal breath sounds, especially over the upperlobes or involved areas.

Sputum microscopy

• Sputum for AFB
• Early morning sputum sample should be tested
• May need to repeat 2-3 times

CBNAAT/Genexpert

• Early morning sputum
• It is more sensitive than microscopy
• It can diagnose TB and also give Rifampicin sensitive/resistance status

Imaging tests

• Chest X ray
• CT chest

Other tests

• Sputum for MTB culture-MGIT
• LPA- Lime probe assay

Tuberculin skin test/montoux test and IGRA/TB gold test

• These tests are used mainly to diagnose latent TB
• Their role in diagnosing active TB is very low

TREATMENT

For drug sensitive TB,treatment include 8 weeks of intensive phase with Isoniazide(H), Rifampicin(R), Ethambutol(E), Pyrazinamide(Z) followed by 16 weeks of continuation phase with Isoniazide(H), Rifampicin(R), Ethambutol(E)

If patient had a history of PTB and ATT intake in the past, then drug sensitivity for latest TB infection should be carefully assess and treated accordingly

T.Benadon 20-40mg OD should be added ATT

Can use other symptomatic medication along with ATT

For drug resistance TB, treatment is complicated which include combination of first and second line Anti tubercular medication which depends on the resistance pattern

First line drugs                                                  Side effects

H-Isoniazid  5mg/kg  – change in memory, Hallucination, Psychosis, Anemia, Neuropathy,  

                                     Gynecomastia, Euphoria

 R-Rifampicin 10mg/kg- Interstitial nephritis, flu, anemia, orange coloured urine, pulmonary

                                        syndrome, contraception failure

E-Ethambutol 15mg/kg – Eye toxicity, Ooptic neuritis, red green colour blindness,

                                         hyperurecimia

Z-Pyrazinamide 25mg/kg – Hepatotoxic, neuropathy, hyperuricemia, arthralgia

Second line drugs:

Levofloxacin

Moxifloxacin

Bedaquiline

Linezolid

Amikacin

Ofloxacin

Ciprofloxacin 

If the patient have latent TB, recommend treatment with medication if the patient at high risk of developing active TB. For active tuberculosis, patient must take ATT drugs for at least six to nine months. The exact drugs and duration of treatment depends on the patient age, overall health, possible drug resistance and where the infection is in the body.

PREVENTION

As TB is an airborne infection, TB bacteria released into the air when someone with infectious TB coughs or sneezes. The risk of infection can be reduced by using a few simple precautions

Good ventilation: As TB can remain suspended in the air for several hours with no ventilation

Natural light: UV light kills off TB bacteria

Good hygiene: covering the mouth and nose when coughing or sneezing reduces the spread of TB bacteria

Use of protective masks: wearing a facemask when you are around other people during the first three weeks of treatment may help lessen the risk of transmission

Stay home: Don’t go to work or school or sleep in a room with other people during the first few weeks of treatment

RED FLAGS:

• Weight loss
• Anorexia
• Evening rise of temperature
• Productive cough over 2 weeks
• Hemoptysis

PIT FALLS:

• Bronchogenic carcinoma
• Lymphomas

PEARLS:

• Always sent for CBNAAT when suspecting TB
• Do not prescribe levofloxacin when suspecting TB

Submitted by

P.Bharathi