Tuberculosis

Tuberculosis

• Is an infectious disease that primarily affects the lung parenchyma. It is also transmitted to other parts of the body, including the meninges, kidneys, bones, and lymph nodes. 

• The primary infectious agent, Mycobacterium Tuberculosis, is an acid-fast aerobic rod that grows slowly and is sensitive to heat and ultraviolet light. 

• A worldwide public health problem that is closely associated with poverty, malnutrition, overcrowding, substandard housing and inadequate health care. 

Transmission and Risk Factors

• TB spreads from person to person by airborne transmission. An infected person releases droplet nuclei (usually particles 1 to 5 um in diameter) through talking, coughing, sneezing, laughing, or singing 

• Larger droplets settle; smaller droplets remain suspended in air and are inhaled by a susceptible person 

• Close contact with someone who has TB, inhalation of airborne nuclei from infected person is proportional to the amount of time spent in same air space, the proximity of the person, and the degree of ventilation 

• Immunocompromised status 

• Substance abuse

• Any person without adequate health care 

• Pre-existing medical conditions or special treatment 

• Immigration from countries with a high prevalence of TB 

• Institutionalization 

• Living in overcrowded, substandard housing 

• Being a healthcare provider

• TB begins with susceptible person inhales mycobacteria and becomes infected. 

• The bacteria are transmitted through the airways to the alveoli, where they are deposited and begin to multiply. The bacilli are transported via the lymph system and bloodstream to the other parts of the body (kidneys, bones, and cerebral cortex) and other areas of the lungs (upper lobes). 

• The body’s immune system responds by initiating an inflammatory reaction. Phagocytes (neutrophils and macrophages) engulf many of the bacteria, and TB specific lymphocytes lyse (destroy) the bacilli and normal tissue.

• The tissue reaction results in the accumulation of exudate in the alveoli causing bronchopneumonia 

• The initial infection occurs 2 to 10 weeks after exposure.

Clinical Manifestations

• The sign and symptoms of TB is insidious 

• Low grade fever 

• Cough- may be non productive or mucopurulent sputum may be expectorated 

• Night sweats 

• Fatigue

• Weight loss 

• Hemoptysis may be present 

• Elder patients usually present with less pronounced symptoms than younger patients 

• In patients with AIDS, extrapulmonary disease is more prevalent

Assessment and Diagnostics

• Complete history, physical examination

• Tuberculin skin test

• Chest x-ray- reveals lesion in the upper lobes 

• Acid fast bacilli smear- contains mycobacterium 

• Sputum culture 

• Clinical manifestations of fever, anorexia, weight loss, night sweats, fatigue, cough and sputum production prompt a more thorough assessment of respiratory function, example; assessing the lungs for consolidation by evaluating breath sounds (diminished, bronchial sounds, crackles), fremitus, and egophony 

Tuberculin Test

• The Mantoux method is used to determine whether a person has been infected with the TB bacillus. 

• Is a standardized, intracutaneous injection procedure and should be performed only by those trained in its administration and reading 

• Tubercle bacillus extract (tuberculin), purified protein derivative (PPD), is injected into the intradermal layer of the inner aspect of the forearm approximately 4 inches below the elbow, using a tuberculin syringe with a half inch 26- or 27-gauge needle 

• 0.1ml of PPD is injected, creating an elevation site in the skin, a well demarcated wheal 6 to 10 mm in diameter 

• The site, antigen, name, strength, lot number, date and time of the test are recorded. The test result is read 48 to 72 hours after injection 

• Test read after 72 hours tend to underestimate the true size of induration (hardening). A delayed localized reaction indicates that person is sensitive to tuberculin

• A reaction occurs when both induration and erythema (redness) are present. After the area is inspected for induration, it is lightly palpated across the injection site, from the area of normal skin to the margins of induration. The diameter of induration (not erythema) is measured in mm as its widest part. 

• Erythema without induration is not considered significant 

• A reaction of 0 to 4mm is considered not significant 

• A reaction of 5mm or greater may be significant in people who are considered high risk. It is defined as positive patients who are HIV positive or have HIV risk factors and are of unknown HIV status, in those who are close contact of someone with active TB, and in those who have chest x-ray results consistent with TB

• An induration of 10mm or greater is usually considered significant in people who have normally or mildly impaired immunity 

• A significant reaction indicates past exposure to M. tuberculosis or vaccination with BCG (Bacille Calmette Guerin) vaccine. This vaccine given to produce a greater resistance to develop TB it is effective 76% of people who receive it. 

• A significant (positive) reaction does not necessarily mean that active disease is present in the body. More than 90% of people who are tuberculin significant reactors do not develop clinical TB 

• A nonsignificant skin test does not exclude TB infection or disease, because patients who are immunocompromised cannot develop an immune response that is adequate to produce a positive skin test. This is referred as anergy.  

QuantiFERON - TB Gold Test

• Is an enzyme linked immunosorbent assay (ELISA) that detects the release of interferon- gamma by white blood cells when the blood of patient with TB is incubated with peptides similar to those in M. tuberculosis 

• The results are available within less than 24 hours and are not affected by prior vaccination with BCG 

• A positive tuberculin skin test or QFT-G only indicates that a person has been infected with TB. It does not indicate whether or not the person has active progression of the disease 

Classification

• Data from the history, physical examination, TB test, chest x-ray, and microbiologic studies are used to classify TB into one of five classes. 

1. Class 0- no exposure, no infection 

2. Class 1- exposure, no evidence of infection 

3. Class 2- latent infection, no disease (positive PPD reaction but no clinical evidence of active TB) 

4. Class 3- disease, clinically active 

5. Class 4- disease, not clinically active 

6. Class 5- suspected disease, diagnosis pending 

Medical Management

1. Pulmonary Tb is treated primarily with antituberculosis agents for 6 to 12 months. A prolonged treatment duration is necessary to ensure eradication of the organisms and to prevent relapse 

2. Primary Drug Resistance- resistance to one of the firs lines antituberculosis agents in people who have not had previous treatment 

3. Secondary or Acquired Resistance- resistance to one or more antituberculosis agents in patients undergoing therapy 

4. Multidrug Resistance- resistance to two agents, INH and Rifampicin. The population at greatest risk for multidrug resistance are those who are HIV positive, institutionalized or homeless. 

Hospitalized Client

1. The client with active TB is placed in isolation precaution in a negative pressure room; to maintain negative pressure the door of the room must be tightly closed. 

2. The room should have at least 6 exchanges of fresh air per hour and should be ventilated the outside environment if possible 

3. The nurse wears a particulate respirator when caring the client and a gown when the possibility of clothing contamination exists 

4. Thorough handwashing is required before and after caring the client 

5. If the client needs to leave the room for a test or procedure, the client is required to wear a mask 

6. Respiratory isolation is discontinued when the client is no longer considered infectious 

7. After the infected individual has received tuberculosis medication for 2 to 3 weeks, the risk of transmission is reduced greatly 

8. Provide the client and family with information regarding TB 

9. Instruct the client to follow the medication regimen regularly 

10. Advise the client of the side effects of the medication and ways of minimizing them to ensure compliance 

11. Inform the client to resume activities gradually 

12. Instruct the client of need adequate nutrition and a well balanced diet 

13. Inform the client and family that respiratory isolation is not necessary because family members have been exposed 

14. Proper respiratory etiquette