Tuberculosis

Tuberculosis (TB) is a serious illness that mainly affects the lungs.

The germs that cause tuberculosis are a type of bacteria.

TB has two forms: inactive (latent) and active (disease). Active TB is

infectious and can be fatal if left untreated.

Tuberculosis spreads easily where people gather in crowds or where

people live in crowded conditions. People with HIV/AIDS and other
people with weakened immune systems have a higher risk of catching
tuberculosis than people with typical immune systems.
 Causes
The main cause of TB is Mycobacterium tuberculosis (MTB), a small,
aerobic, nonmotile bacillus. It divides every 16 to 20 hours, which is
slow compared with other bacteria, which usually divide in less than
an hour.
Mycobacteria have a complex, lipid-rich cell envelope, with the high
lipid content of the outer membrane acting as a robust barrier
contributing to their drug resistance. If a Gram stain is performed,
MTB either stains very weakly "Gram-positive" or does not retain dye
as a result of the high lipid and mycolic acid content of its cell wall.
MTB can withstand weak disinfectants and survive in a dry state for
weeks. In nature, the bacterium can grow only within the cells of a
host organism, but MTB can be cultured in the laboratory.

Transmission
Tuberculosis spreads through the air when people with active
pulmonary TB cough, sneeze, speak, or sing, releasing tiny
airborne droplets containing the bacteria. Anyone nearby can breathe
in these droplets and become infected. The droplets can remain
airborne and infective for several hours, and are more likely to persist
in poorly ventilated areas.
 Symptoms
Stages of Infection
Tuberculosis (TB) progresses through distinct stages.

1. Primary Infection:
This is the initial stage when a person is first exposed to
Mycobacterium tuberculosis bacteria.
In many cases, the primary infection causes no noticeable symptoms,
and the immune system can contain the infection.
Some individuals may experience mild, flu-like symptoms or fever.
Most primary infections are followed by latent TB infection.

2. Latent TB Infection:
In this stage, the bacteria remain alive but inactive, and the person
experiences no symptoms and cannot spread the disease.
This stage can persist for years or even a lifetime. Approximately
90% of people with TB infection develop latent TB. Latent TB can be
detected through skin or blood tests.
If the immune system weakens, the bacteria can reactivate and
progress to active disease.
3. Active TB Disease:
The bacteria multiply and damage tissues, typically in the lungs
(pulmonary TB) but potentially in other parts of the body
(extrapulmonary TB).
Symptoms of active TB disease include:
- Persistent cough lasting more than 3 weeks.
- Chest pain.
- Coughing up blood (haemoptysis).
- Fatigue and weakness.
- Night sweats and chills.
- Fever.
- Loss of appetite and weight loss.
Extrapulmonary TB can cause symptoms related to the affected
organ, such as swollen glands, bone pain, or neurological problems.
Active TB disease is contagious and can be spread to others through
airborne droplets. Active TB disease requires prompt medical
treatment to prevent serious complications and further spread.
 Treatment
Treatment for Latent TB
These are the three treatment options:
  Isoniazid (INH)
 Rifampin (Rifadin, Rimactane)
 Isoniazid and rifapentine

Treatment for Active TB

These four medications are most commonly used to treat it:
 Ethambutol (EMB)
 Isoniazid (INH)
 Pyrazinamide (PZA)
 Rifampin (RIF)

Treatment for Drug-Resistant TB

If you have a TB strain that doesn’t respond to the usual medications
used to treat TB, you have a drug-resistant strain.
They include:
 Antibiotics called fluoroquinolones
 An injectable antibiotic, such as amikacin (Amikin), and
streptomycin
 Newer antibiotic treatments, such as bedaquiline (Sirturo),
ethionamide (Trecator), and para-aminosalicylic acid. These are
given in addition to other medications.

Prevention
During the first 2 to 3 weeks, you will be able to pass TB bacteria to
others. Protect others with these steps:
  Stay home.
 Isolate at home.
 Ventilate the room.
 Wear face masks.
 Cover your mouth.

Vaccinations
In countries where tuberculosis is common, infants often are
vaccinated with the Bacillus Calmette-Guerin (BCG) vaccine. This
protects infants and toddlers who are more likely to have
active TB disease in the fluid surrounding the brain and spinal cord.

Case Study 1
Respiratory Isolation
A 31-year-old Caucasian male presented to the Emergency
Department (ED) after experiencing gross haemoptysis. He had a 2-
month history of productive cough, a 25-pound weight loss, night
sweats, and fatigue. A CXR (Chest X-Ray) revealed bilateral cavitary
infiltrates. The initial sputum specimen was smear positive 4+ and
was submitted for a Nucleic Acid Amplification Test (NAAT),
culture, and sensitivity. The patient has a history of heavy alcohol and
drug use. He is HIV negative, Hepatitis B and C positive, has a long
history of cigarette use, and a chronic smoker’s cough.
The patient’s NAAT was positive for MTB. He was immediately
started on a standard four drug regimen and tolerated the medications
well. After four days of hospitalization the physician called the local
health department to report the person with TB disease and his
intention to discharge the patient with a prescription for INH, RIF,
PZA, EMB, and vitamin B6.
The patient was fairly cooperative during the first week of
hospitalization, however, the nursing staff reported the patient had
been out in the hallway a couple of times without his mask. The
hospital staff was becoming anxious, so the physician called the local
health department to coordinate the discharge.

Sputa were obtained by the local health department during his first
week home, the results were still positive (1+ AFB [Acid Fast Bacilli-
a bacteria that causes TB] smear, 0 AFB smear, 1+ AFB smear) and
home isolation continued. At the next visit the patient was not home.
The wife shared that “he got stir crazy,” went drinking with his
friends Friday night, and has not been back since.
Two weeks later, the patient was found at a relative’s house. After re-
educating the patient, he was adherent to the respiratory isolation
precautions. During this time, three consecutive sputa results were
reported as negative, his symptoms improved and he remained on an
appropriate TB treatment regimen for two weeks. At that point, the
local health department discontinued respiratory isolation precautions.