Tuberculosis definition

Multisystemic chronic necrotising disease caused by Mycobacterium Tuberculosis

Tuberculosis pathogenesis

Mycobacterium tuberculosis is transmitted via inhalation of droplet nuclei and reaches the alveoli, where it is phagocytosed by macrophages but survives intracellularly by inhibiting phagolysosome fusion. This triggers a cell-mediated immune response, leading to granuloma (tubercle) formation with caseous necrosis. The infection may then be contained as latent TB or progress to active disease if immune control fails.

TB infection control

1. Administrative

Find TB early
Diagnose early
Treat early

2. Environmental

Open windows
Ventilation
UV light

3. Personal Protection

N95 for staff
Surgical mask for patient

Administrative controls TB

• Early identification of presumptive TB cases
• Prompt diagnosis
• Rapid initiation of treatment
• Separation (isolation) of infectious patients
• Screening of high-risk individuals
• Health education on cough hygiene

Environmental controls TB

A. Adequate Ventilation

• Open windows and doors
• Natural ventilation
• Cross-ventilation

B. Mechanical Ventilation

• Fans and exhaust systems

C. Ultraviolet Germicidal Irradiation (UVGI)

• UV lights used in high-risk healthcare settings

Personal Protective Measures TB

For Healthcare Workers: N95 Respirators

• Filter airborne particles
• Used when caring for infectious TB patients

For Patients: Surgical Masks

• Reduce spread of infectious droplets

Cough etiquette/respiratory hygiene TB

Patients should be advised to:

• Cover mouth and nose when coughing or sneezing
• Use tissues when available
• Dispose of tissues properly
• Wash hands regularly

Isolation of infectious patients TB

Patients with suspected or confirmed pulmonary TB may require:

• Isolation rooms
• Reduced contact with vulnerable individuals

Especially:

• Children
• HIV-positive patients
• Immunocompromised individuals

Community-level infection control

Reduce Overcrowding

• Improve housing conditions
• Improve ventilation

Health Education

• Encourage early presentation
• Reduce stigma
• Promote treatment adherence

TB Preventive Therapy(TPT)

TB preventive therapy is the administration of anti-tuberculosis medication to individuals at risk of developing active TB in order to prevent progression from latent infection to active disease. It is commonly given to household contacts, especially children under five years of age, and people living with HIV after active TB has been excluded.

Pyridoxine

Vitamin B6

TB Prevention

TB Prevention

Primary
BCG
Infection control
Health education

Secondary
Early diagnosis
Contact tracing
Screening
TB Preventive Therapy

Tertiary
Adherence
Prevent complications

Rehabilitation

What is a Ghon complex?

A Ghon focus (small subpleural granuloma in the lower/mid lung) + enlarged ipsilateral hilar/mediastinal lymph nodes. It is the hallmark of primary TB in a child or immunocompetent host.

What is a Ranke complex?

A healed, calcified Ghon complex seen years later on CXR. Shows a calcified lung nodule + calcified hilar lymph node. Indicates the patient was infected but contained the bacteria (now latent).

What is GeneXpert?

A rapid molecular test (NAAT) that detects M. tuberculosis DNA and Rifampicin (RIF) resistance (via rpoB gene mutation) directly from sputum within 2 hours. In Zambia, it is the frontline diagnostic test for all presumptive TB patients.

Define MDR-TB

Multi-Drug Resistant TB: Resistance to at least Isoniazid (INH) AND Rifampicin (RIF) – the two most powerful first-line anti-TB drugs.

Define XDR-TB

Extensively Drug-Resistant TB: MDR-TB PLUS resistance to any Fluoroquinolone (e.g., Levofloxacin) AND at least one of the second-line injectables (Amikacin, Kanamycin, or Capreomycin).

Outline treatment of drug-susceptible TB

1. Intensive phase (2 months)

RHZE daily

2. Continuation phase (6 months)

Fixed-Dose Combinations (FDCs) are used for adult TB.
Directly Observed Therapy (DOT) is mandatory for the entire course.