TB diagnostics

Question 1

what is TB

Answer 1

TB is an infectious disease caused by Mycobacterium complex that affects mainly the lungs (pulmonary TB) but can also attack any part of the body (extrapulmonary TB)

Question 2

effects of poorly managed TB treatment

Answer 2

can result in drug resistance. Drug-resistant strains of TB can be transmitted to others.

Question 2

Mention the 4 drugs used as the standard treatment for TB

Answer 2

1. rifampicin
2. isoniazid
3. ethambutol
4. pyrazinamide

Question 3

what are the effects of rifampicin resistent in patients withTB

Answer 3

TB require longer treatment (lasting up to 2 years) with expensive second-line agents that have more serious side effects.

Question 4

What are the symptoms of TB

Answer 4

1. The most common symptom of pulmonary TB is a productive cough lasting for more than 2 weeks.
2. Other respiratory symptoms may include shortness of breath, chest pains and haemoptysis (coughing up blood).
3. People with TB may also lose their appetite, lose weight, have a fever or night sweats, or feel tired.

~ Symptoms may vary depending on a person’s age, HIV status and the site of the disease (pulmonary or extra pulmonary).

Question 5

A persons risk of acquiring TB

Answer 5

depends on how long they were exposed to someone with pulmonary TB, the intensity of the exposure, as well as the strength of the person’s immune system.

Question 5

Explain the transmission of TB bacilli

Answer 5

1. A person with TB expels bacilli in small droplets of respiratory secretions. ( person to person)
2. The secretions quickly evaporate leaving “droplet nuclei” that are less than 5 m in diameter. ( Air borne )
3. Droplet nuclei of this size contain 1–3 bacilli and can remain in the environment for an extended time. ( Confined )
4. Following inhalation, droplet nuclei are able to travel deep into the lungs to produce infection.

Question 6

The role of TB laboratory network in TB control

Answer 6

1. Bacteriological confirmation of TB and drug-resistant TB
2. Monitoring of treatment progress
3. Support for surveillance studies (e.g., drug-resistance surveys and prevalence surveys).

Question 6

Why is microscopy recommended for all levels of laboratories, including peripheral and higher levels?

Answer 6

Microscopy is recommended for all levels of laboratories because it is a fundamental diagnostic tool that is accessible and essential for detecting tuberculosis (TB) and monitoring treatment responses, making it indispensable across all settings.

Question 7

What precautions are needed for microscopy, and why is it considered safe with minimal biosafety precautions?

Answer 7

Microscopy can be safely conducted with minimal biosafety precautions because it typically involves the examination of fixed and stained specimens, which are less likely to pose a biohazard compared to other types of samples.

Question 7

Why is microscopy required to monitor responses to anti-TB therapy?

Answer 7

Microscopy is required to monitor responses to anti-TB therapy because it allows for the direct observation of the presence or absence of Mycobacterium tuberculosis in sputum samples, providing a straightforward method to assess treatment effectiveness.

Question 8

What advancements does the WHO recommend in the field of TB microscopy, and why?

Answer 8

The WHO recommends phasing in LED fluorescence microscopy to replace conventional bright-field microscopy and Ziehl-Neelsen staining. LED fluorescence microscopy offers improved sensitivity and specificity, making it a more effective tool for TB diagnosis.

Question 9

Why is culture recommended specifically for national or regional level laboratories

Answer 9

Culture requires advanced laboratory infrastructure and a high level of biosafety precautions, which are typically available at national or regional level laboratories. These facilities have the resources and expertise to safely handle and process cultures for accurate TB diagnosis

Question 10

What are the main differences between solid culture and liquid culture in TB diagnostics?

Answer 10

Solid Culture: Less expensive, but results take longer to obtain.

Liquid Culture: More expensive, but provides results more rapidly and is more sensitive, detecting TB bacteria more efficiently

Question 11

Why does liquid culture require a higher level of biosafety precautions compared to other methods?

Answer 11

Liquid culture involves handling larger volumes of infectious materials, increasing the risk of aerosol generation and exposure. This necessitates stricter biosafety measures to protect laboratory personnel and prevent contamination

Question 16

What is the significance of rapid species identification in TB diagnostics?

Answer 16

Rapid species identification is crucial for timely and appropriate treatment. It allows for the quick determination of the presence of Mycobacterium tuberculosis and differentiates it from other non-tuberculous mycobacteria, ensuring accurate diagnosis and effective treatment plans