Tuberculosis

TB Transmission Transmission is defined as the spread of an organism, such as M. tuberculosis, from one person to another.

Tuberculosis Second most common cause of death from infectious disease In US, higher prevalence in areas with large population of Native Americans Health care workers are considered to be at high risk. Resurgence High rates of TB with HIV infection Multidrug-resistant strains of M. tuberculosis Worldwide, TB occurs disproportionately in the poor, the underserved, and minorities. In the United States, persons at risk include the homeless, residents of inner-city neighborhoods, foreign-born persons, older adults, those in institutions (long-term care facilities, prisons), IV injecting drug users, persons at poverty level, and those with poor access to health care. 3

TB Transmission Types of Mycobacteria M. tuberculosis causes most TB cases in U.S. Mycobacteria that cause TB: M. tuberculosis M. bovis M. africanum M. microti M. canetti Mycobacteria that do not cause TB M. avium complex M. tuberculosis

TB Transmission TB is spread person to person through the air via droplet nuclei M. tuberculosis may be expelled when an infectious person: Coughs Sneezes Speaks Sings Transmission occurs when another person inhales droplet nuclei

Dots in air represent droplet nuclei containing TB Transmission Dots in air represent droplet nuclei containing M. tuberculosis

TB Transmission Probability that TB will be transmitted depends on: Infectiousness of person with TB disease Environment in which exposure occurred Length of exposure Virulence (strength) of the tubercle bacilli The best way to stop transmission is to: Isolate infectious persons Provide effective treatment to infectious persons as soon as possible

TB Pathogenesis Pathogenesis is defined as how an infection or disease develops in the body.

TB Pathogenesis Latent TB Infection (LTBI) Occurs when tubercle bacilli are in the body, but the immune system is keeping them under control Detected by the Mantoux tuberculin skin test (TST) or by blood tests such as interferon-gamma release assays (IGRAs) which include: QuantiFERON®-TB Gold test (QFT-G) QuantiFERON®-TB Gold In-Tube (QFT-GIT) T-Spot®.TB test (T-SPOT) People with LTBI are NOT infectious

TB Pathogenesis TB Disease Develops when immune system cannot keep tubercle bacilli under control May develop very soon after infection or many years after infection About 10% of all people with normal immune systems who have LTBI will develop TB disease at some point in their lives People with TB disease are often infectious

TB Pathogenesis Droplet nuclei containing tubercle bacilli are inhaled, enter the lungs, and travel to small air sacs (alveoli)

Tubercle bacilli multiply in alveoli, where TB Pathogenesis Tubercle bacilli multiply in alveoli, where infection begins

TB Pathogenesis A small number of tubercle bacilli enter bloodstream and spread throughout body

TB Pathogenesis LTBI Within 2 to 8 weeks the immune system produces special immune cells called macrophages that surround the tubercle bacilli These cells form a barrier shell that keeps the bacilli contained and under control (LTBI)

TB Pathogenesis TB Disease If the immune system CANNOT keep tubercle bacilli under control, bacilli begin to multiply rapidly and cause TB disease This process can occur in different places in the body

Latent TB Infection (LTBI) TB Disease (in the lungs) LTBI vs. TB Disease Latent TB Infection (LTBI) TB Disease (in the lungs) Inactive, contained tubercle bacilli in the body Active, multiplying tubercle bacilli in the body TST or blood test results usually positive Chest x-ray usually normal Chest x-ray usually abnormal Sputum smears and cultures negative Sputum smears and cultures may be positive No symptoms Symptoms such as cough, fever, weight loss Not infectious Often infectious before treatment Not a case of TB A case of TB

Progression to TB Disease Risk of developing TB disease is highest the first 2 years after infection People with LTBI can be given treatment to prevent them from developing TB disease Detecting TB infection early and providing treatment helps prevent new cases of TB disease

Progression to TB Disease Some conditions increase probability of LTBI progressing to TB disease Infection with HIV Chest x-ray findings suggestive of previous TB Substance abuse Recent TB infection Prolonged therapy with corticosteroids and other immunosuppressive therapy, such as prednisone and tumor necrosis factor-alpha [TNF-α] antagonists Organ transplant Silicosis Diabetes mellitus Severe kidney disease Certain types of cancer Certain intestinal conditions Low body weight

Progression to TB Disease People Exposed to TB Not TB Infected Latent TB Infection (LTBI) Not Infectious Not Infectious Negative TST or QFT-G test result Positive TST or QFT-G test result No TB Infection May go on to develop TB disease Latent TB Infection Figure 1.5

Progression to TB Disease TB and HIV In an HIV-infected person, TB can develop in one of two ways: Person with LTBI becomes infected with HIV and then develops TB disease as the immune system is weakened Person with HIV infection becomes infected with M. tuberculosis and then rapidly develops TB disease Image credit: Mississippi State Department of Health

Progression to TB Disease TB and HIV People who are infected with both M. tuberculosis and HIV are much more likely to develop TB disease TB infection and NO risk factors TB infection and HIV infection (pre-Highly Active Antiretroviral Treatment [HAART]) Risk is about 5% in the first 2 years after infection and about 10% over a lifetime Risk is about 7% to 10% PER YEAR, a very high risk over a lifetime

Bacilli may reach any part of the body, but common sites include: Sites of TB Disease Bacilli may reach any part of the body, but common sites include:

Sites of TB Disease Location Frequency Pulmonary TB Extrapulmonary TB Lungs Most TB cases are pulmonary Extrapulmonary TB Places other than lungs such as: Larynx Lymph nodes Pleura Brain Kidneys Bones and joints Found more often in: HIV-infected or other immunosuppressed persons Young children Miliary TB Carried to all parts of body, through bloodstream Rare

TB Classification System Based on pathogenesis of TB Class Type Description No TB exposure Not infected No history of TB exposure Negative result to a TST or IGRA 1 TB exposure No evidence of infection History of TB exposure Negative result to a TST (given at least 8- 10 weeks after exposure) or IGRA 2 TB infection No TB disease Positive result to a TST or IGRA Negative smears and cultures (if done) No clinical or x-ray evidence of active TB disease

TB Classification System Based on pathogenesis of TB Class Type Description 3 TB, clinically active Positive culture (if done) for M. tuberculosis Positive result to a TST or IGRA, and clinical, bacteriological, or x-ray evidence of TB disease 4 Previous TB disease (not clinically active) Medical history of TB disease Abnormal but stable x-ray findings Positive result to a TST or IGRA Negative smears and cultures (if done) No clinical or x-ray evidence of active TB disease 5 TB suspected Signs and symptoms of TB disease, but evaluation not complete

Clinical Manifestations Early stages are usually free of symptoms. People with LTBI have a positive skin test but are asymptomatic. 26

Clinical Manifestations Fatigue Malaise Anorexia Weight loss Low-grade fevers Night sweats People with LTBI have a positive skin test but are asymptomatic. 27

Clinical Manifestations Cough becomes frequent. Hemoptysis is not common and is usually associated with advanced disease. Dyspnea is unusual. 28

Clinical Manifestations Acute symptoms (generalized flu symptoms) High fever Chills Pleuritic pain Productive cough 29

Complications Miliary TB Large numbers of organisms invade the bloodstream and spread to all organs. Acute or chronic symptoms It can occur as a result of primary disease or reactivation of latent infection. Acute symptoms include fever, dyspnea, and cyanosis. Chronic symptoms include the systemic manifestations of weight loss, fever, and gastrointestinal (GI) disturbance. Hepatomegaly, splenomegaly, and generalized lymphadenopathy may be present. 30

Complications Pleural effusion Empyema Caused by bacteria in pleural space Inflammatory reaction with plural exudates of protein-rich fluid Empyema Pleural TB can result from either primary disease or reactivation of a latent infection. Empyema is less common than effusion but may occur from large numbers of tubercular organisms in the pleural space. 31

Complications TB pneumonia Large amounts of bacilli discharging from granulomas into lung or lymph nodes The clinical manifestations are similar to those of bacterial pneumonia. 32

Complications Other organ involvement CNS—Meninges Bone and joint tissue Kidneys 33

Complications Other organ involvement Adrenal glands Lymph nodes Genital tracts 34

Diagnostic Studies Skin testing Intradermal administration of tuberculin Induration at injection site indicates exposure. Sensitivity remains for life, and individual should not be tested again. The test is administered by injecting 0.1 mL of PPD intradermally on the dorsal surface of the forearm. The test is read by inspection and palpation 48 to 72 hours later for the presence or absence of induration. The indurated area (if present) is measured and recorded in millimeters with 0 for no induration. The reaction occurs 2 to 12 weeks after initial exposure to the organisms. 35

Diagnostic Studies Skin testing Response ↓ in immune compromised patients Reactions ≥5 mm considered positive 36

Diagnostic Studies Skin testing Two-step testing recommended for health care workers getting repeated testing and those with decreased response to allergens. In these people, a second TST may cause an accelerated response (“booster effect”) that may be misinterpreted as a new conversion. 37

Diagnostic Studies Chest x-ray Cannot make diagnosis solely on x-ray Upper lobe infiltrates, cavitary infiltrates, and lymph node involvement suggest TB. 38

Diagnostic Studies Bacteriologic studies Stained sputum smears examined for acid-fast bacilli Required for diagnosis The culture to grow the organisms for confirmatory diagnosis can take up to 8 weeks. 39

Diagnostic Studies Bacteriologic studies On different days, three consecutive sputum samples Could also be collected from Gastric washings CSF Fluid from an abscess or effusion 40

Collaborative Care Hospitalization not necessary for most patients Drug therapy used to prevent or treat active disease Promoting and monitoring compliance are critical for treatment to be successful. 41

Drug Therapy Active disease Four drugs are used in initial phase for maximum effectiveness. Treatment is aggressive to combat resistant strains of TB. In most circumstances, the treatment regimen for patients with previously untreated TB consists of a 2-month initial phase with four-drug therapy (INH, rifampin [Rifadin], pyrazinamide [PZA], and ethambutol). If drug susceptibility test results indicate that bacteria are susceptible to all drugs, ethambutol may be discontinued. 42

Drug Therapy Directly observed therapy (DOT) Noncompliance is major factor in multidrug resistance and treatment failures. Requires watching patient swallow drugs Preferred to ensure adherence In many areas, the public health nurse administers DOT at a clinic site. 43

Drug Therapy Active disease Patients should be taught about side effects and when to seek medical attention. Liver function should be monitored. The major side effect of isoniazid, rifampin, and pyrazinamide is nonviral hepatitis. 44

Drug Therapy Latent TB infection Usually treated with INH for 6 to 9 months HIV patients should take INH for 9 months. Because a person with LTBI has fewer bacteria, treatment is much easier. Usually, only one drug is needed. Drug therapy regimens for LTBI are presented in Table 28-13. The 9-month regimen is more effective, but compliance issues may make the 6-month regimen preferable. An alternative 4-month therapy with rifampin may be indicated if the patient is resistant to INH. 45

Drug Therapy Vaccine Bacille Calmette-Guérin (BCG) vaccine to prevent TB is currently in use in many parts of the world. In United States, not recommended Can result in positive PPD reaction 46

Nursing Assessment Assess for Productive cough Night sweats Afternoon temperature elevation Weight loss Pleuritic chest pain Crackles over apices of lungs If the patient has a productive cough, early morning is the ideal time to collect sputum specimens for an acid-fast bacillus smear. 47

Nursing Diagnoses Ineffective breathing pattern Imbalanced nutrition: Less than body requirements Noncompliance 48

Nursing Diagnoses Ineffective health maintenance Activity intolerance 49

Planning Goals Comply with therapeutic regimen. Have no recurrence of disease. Have normal pulmonary function. Take appropriate measures to prevent spread of disease. 50

Nursing Implementation Ultimate goal in the United States is eradication. Selective screening programs in high-risk groups to detect TB Identify contacts of patient with TB. The person with a positive tuberculin skin test should have a chest x-ray to assess for the presence of active TB disease. 51

Nursing Implementation Acute intervention Airborne isolation Appropriate drug therapy Immediate medical workup Medical workup includes chest x-ray, sputum smear, and culture. Isolation requires a single-occupancy room with negative pressure and airflow of 6 to 12 exchanges per hour. 52

Nursing Implementation Teach patient Cover nose and mouth with tissue when coughing, sneezing, or producing sputum Hand washing after handling sputum-soiled tissues The tissues should be thrown into a paper bag and disposed of with the trash, burned, or flushed down the toilet. Close contacts of the person with TB should be screened (usually with the TST). If the person has LTBI or active TB disease, he or she should be treated with anti-TB drugs. 53

Nursing Implementation Ambulatory and home care Ensure that patient can adhere to treatment. Teach symptoms of recurrence. Patients who have responded clinically are discharged home (even with positive cultures) if their household contacts have already been exposed and the patient is not posing a risk to susceptible persons. The public health nurse will be responsible for follow-up on household contacts and assessment of the patient for compliance. If compliance is an issue, the public health agency may be responsible for DOT. 5% of individuals experience relapses. 54

Evaluation Expected outcomes Complete resolution of disease Normal pulmonary function Absence of any complications No transmission of TB 55