Tuberculosis Flashcards
Definition of Tuberculosis
communicable infectious disease caused by Mycobacterium tuberculosis which produces silent, latent infection or a progressive active disease, regarded as leading infectious killer disease
Diagnosis of TB in children
• Tuberculin Skin Test (TST)
• Chest X-ray
• microscopy
• culture of sputum, fluid, and tissue samples
Cause of TB
Mycobacterium tuberculosis bacilli
Transmission:
Spread through micro-sized droplet nuclei during coughing and sneezing
risk of infection with cavitary and laryngeal TB
- Cavitary pulmonary TB-Patients with cough can infect one person per month until treated
- Laryngeal TB-Even talking can spread M. tuberculosis, increasing transmission risk
Immune System Role
Tasked with recognizing and suppressing M. tuberculosis
Key Cell Types
Macrophages
CD4 T-Lymphocytes (Helper lymphocytes)
CD8 T-Lymphocytes (Cytotoxic/suppressor lymphocytes)
Macrophages’ Function
- Present antigens
- activate interleukins
- secrete interferons
- and activate other macrophages to destroy M. tuberculosis.
Cytotoxic T-Lymphocytes
Responsible for destroying cells harboring Mycobacterium
Immuno-regulatory Role of T-Lymphocytes
T-Lymphocytes contribute to the host’s resistance to developing infection.
HIV Impact
In HIV, destruction of CD4 T-Lymphocytes increases the risk of developing active TB disease
Risk factors for TB
- Previous exposure to pulmonary TB case
- History of previous TB
- Immune status
- Close contacts to TB patients
- Race and ethnicity
- Age, gender, and occupation
- HIV status
- Location and place of birth
- Urban vs rural areas
- Underprivileged patients
- Recalcitrant patients
- History of working at mines
- History of diabetes, smoking, alcoholism, malnutrition
- Prolonged treatment with steroids
Diagnosis of TB
- Sputum smear microscopy
- microbiology culture and sensitivity
- molecular assays like GeneXPert, chest X-ray
- clinical presentation evaluation
M. tuberculosis
Bacilli causing TB, transmitted from person to person through microsize droplet nuclei dispersed through coughing and sneezing
Risk factors for TB in children
- History of recent contact with TB case
- Age
- Time since exposure/infection
- Immune status
Monitoring parameters for adverse drug reactions
- Adherence to therapy
- Adverse drug reactions specific for each medication
- Smear test q 1-2 weeks to be negative in ~ 2 weeks
- Sputum culture q 2-3 months to be negative at 2 months
- Liver function tests
- Serum creatinine
- Eye examinations
Management of TB: 1st Line Medicine
- Isoniazid (H)
- Rifampicin (R)
- Pyrazinamide (Z)
- Ethambutol (E)
- Streptomycin (S)
Risk factors for TB
- Prolonged treatment with steroids
- History of recent contact with TB case
- Age i.e. the very young < 3 years
- Time since exposure/infection (TB disease likely to develop within 1 year)
- Immune status – increased risk of TB disease if have HIV infection, malnutrition, immune suppressive therapy e.g. chemotherapy, corticosteroids
Goal of management of TB
- Prompt resolution of signs and symptoms of disease
- Cure the patients (in a short period of time)
- Restore quality of life
- Prevent morbidity and mortality
- Prevent relapse and development of drug resistance
- Prevent TB transmission to others
Prophylaxis for TB patients
Children: Isoniazid
HIV positive children and adults: Cotrimoxazole – daily dosing
Fixed Combination First-line Anti-TB Agents in Paediatrics
Recommended regimen for TB
* New patients < 30 kg: 2HRZE/4HR
* New patients ≥ 30 kg: 2HRZE/4HRE
* Retreatment: 2HRZES/1HRZE/5HRE
Non-Pharmacological management of TB
- Prevention of spread of disease through isolation and infection control guidelines
- Contact investigation/tracing
- Replenishment to normal weight
Clinical presetation
- Generalized symptoms:
– Loss of appetite
– Weight loss
– Malaise
– Fever ≥ 2 weeks
– Night sweats - As disease progresses:
– Persistent cough – productive cough ≥ 2 weeks
– Shortness of breath, chest pains or hemoptysis
Physical exams and radiological findings consistent with TB
- Physical examination: lungs
- Abnormal with crepitations
- CXR – radiographic findings:
– Patchy or nodular infiltrate in apical areas of upper
lobe or superior segment of lower lobes
– Cavitation ∓ fluid (as disease progresses)
Clinical presentation: Paediatric
- Weight loss or failure to thrive
- Enlargement of lymph nodes (> 1 x 1 cm)
- Cough for ≥ 2 weeks
- Fever for ≥ 2 weeks
- Fatigue, reduced playfulness
- Profuse night sweats ≥ 2 weeks
- Physical examination
– Cough, wheezing, respiratory distress
– Haemoptysis – rare in children w/ PTB
