Tuberculosis

Implementation: Acute Care 1

Airborne isolation Single-occupancy room with 6-12 airflow exchanges/hour Health care workers wear high-efficiency particulate air (HEPA) masks Immediate medical workup Appropriate drug therapy

Diagnostic Studies 4

Chest x-ray Cannot make diagnosis solely on x-ray May appear normal in a patient with TB Bacteriologic studies Required for diagnosis Consecutive sputum samples obtained on 3 different days Stained sputum smears examined for AFB Culture results can take up to 8 weeks

Complications of TB

Appropriately treated pulmonary TB typically heals without complications except for scarring and residual cavitation within the lung. Significant pulmonary damage, although rare, can occur in patients who are poorly treated or who do not respond to TB treatment. Military TB is the widespread dissemination of the mycobacterium. The bacteria are spread via the bloodstream to several distant organs. The infection is characterized by a large amount of TB bacilli and may be fatal if left untreated. Fever, cough, and lymphadenopathy are present.

The American Thoracic Society classifies TB based on development of the disease:

Class 0: No TB exposure, not infected (no history of exposure) Class 1: TB exposure, no evidence of infection (history of exposure) Class 2: Latent TB infection -TB infection without disease (significant reaction to tuberculin skin test, no clinical evidence of TB) Class 3: TB infection with clinically active disease (positive bacteriologic studies or both a significant reaction to tuberculin skin test and clinical or x-ray evidence of current disease) Class 4: TB, but not clinically active. No current disease (history of previous episode of TB, no clinical or x-ray evidence of current disease) Class 5: TB suspect (diagnosis pending); person should not be in this classification for more than 3 months

Drug Therapy

Directly observed therapy (DOT) Noncompliance is major factor in multidrug resistance and treatment failures Requires watching patient swallow drugs Preferred strategy to ensure adherence May be administered by public health nurses at clinic site

Clinical Manifestations

Dyspnea is a late symptom that may signify considerable pulmonary disease or a pleural effusion. Hemoptysis, which occurs in less than 10% of patients with TB, is also a late symptom. The clinical manifestations of extrapulmonary TB are dependent on the organs infected. For example, renal TB can cause dysuria and hematuria. A change in cognitive function may be the only initial presenting sign of TB in an older person

Assessment

History Physical symptoms Productive cough Night sweats Afternoon temperature elevation Weight loss Pleuritic chest pain Crackles over apices of lungs Sputum collection

Diagnostic Studies 3

Interferon-γ gamma release assays (IGRAs) Detects T-cells in response to Mycobacterium tuberculosis Includes QuantiFERON-TB Rapid results Several advantages over TST but more expensive

Class 2

Latent TB infection -TB infection without disease (significant reaction to tuberculin skin test, no clinical evidence of TB)

Etiology and Pathophysiology 1

M. tuberculosis is a gram-positive, acid-fast bacillus (AFB) that is usually spread from person to person via airborne particles expectorated when breathing, talking, singing, sneezing, and coughing. A process of evaporation leaves small droplet nuclei, 1 to 5 μm in size. These droplets contain M. tuberculosis. TB is not highly infectious, as transmission usually requires close, frequent, or prolonged exposure. Factors that influence the likelihood of transmission include the (1) number of organisms expelled into the air (2) concentration of organisms (small spaces with limited ventilation would mean higher concentration) (3) length of time of exposure (4) immune system of the exposed person

Etiology and Pathophysiology 3

M. tuberculosis is aerophilic (oxygen-loving) and has an affinity for the lungs. However, the infection can spread via the lymphatic system and find favorable environments for growth in other organs, including the cerebral cortex, spine, epiphyses of the bone, and adrenal glands.

Class 0

No TB exposure, not infected (no history of exposure)

Implementation: Ambulatory Care

Notification of the public health department is required. 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. Because about 5% of individuals experience relapses, teach the patient to recognize the symptoms that indicate recurrence of TB. Instruct the patient about certain factors that could reactivate TB, such as immunosuppressive therapy, malignancy, and prolonged debilitating illness. Because smoking is associated with poor outcomes in TB, patients should be encouraged to quit.

Multi-Drug Resistant TB

Once a strain of M. tuberculosis develops resistance to two of the most potent first-line anti-tuberculosis drugs (e.g., isoniazid [Isoniazid], rifampin [Rifadin]), it is defined as multidrug-resistant tuberculosis (MDR-TB). Extensively drug-resistant TB (XDR-TB) occurs when the organism is also resistant to any of the fluoroquinolones plus any injectable antibiotic agent. Resistance results from several problems, including incorrect prescribing, lack of public health case management, and patient nonadherence to the prescribed regimen.

Drug Therapy for Active Disease 2

Patients should be taught about side effects and when to seek medical attention Liver function should be monitored Alternatives are available for those who develop a toxic reaction to primary drugs

Clinical Manifestations 1

People with LTBI have a positive skin test but are asymptomatic. Symptoms of pulmonary TB usually do not develop until 2 to 3 weeks after infection or reactivation. The characteristic pulmonary manifestation is an initial dry cough that frequently becomes productive with mucoid or mucopurulent sputum. Active TB disease may initially manifest with constitutional symptoms such as fatigue, malaise, anorexia, unexplained weight loss, low-grade fevers, and night sweats.

Classification of TB

TB can also be classified according to its presentation - primary, latent, or reactivated and whether it is pulmonary or extra-pulmonary. Primary TB infection: The majority of people mount effective immune responses to encapsulate these organisms for the rest of their lives, preventing primary infection from progressing to disease. Latent TB infection (LTBI) is a TB infection in a person who does not have active TB disease. People with LTBI have a positive skin test but are asymptomatic. These individuals cannot transmit the TB bacteria to others but can develop active TB disease at some pointIf the initial immune response is not adequate, the body cannot contain the organisms. As a result, the bacteria replicate, and active TB disease results. When active disease develops within the first 2 years of infection, it is termed primary TB. Individuals co-infected with HIV are at greatest risk for developing active TB.

Class 1

TB exposure, no evidence of infection (history of exposure)

Class 3

TB infection with clinically active disease (positive bacteriologic studies or both a significant reaction to tuberculin skin test and clinical or x-ray evidence of current disease)

Class 5

TB suspect (diagnosis pending); person should not be in this classification for more than 3 months

Class 4

TB, but not clinically active. No current disease (history of previous episode of TB, no clinical or x-ray evidence of current disease)

Implementation: Acute Care 2

Teach patients to cover the nose and mouth with paper tissues every time they cough, sneeze, or produce sputum. The tissues should be thrown into a paper bag and disposed of with the trash, burned, or flushed down the toilet. Emphasize careful hand washing after handling sputum and soiled tissues. If patients need to be out of the negative-pressure room, they must wear a standard isolation mask to prevent exposure to others. Minimize prolonged visitation to other parts of the hospital. Identify and screen close contacts of the person with TB. Anyone testing positive for TB infection will undergo further evaluation and needs to be treated for either LTBI or active TB disease.

Evaluation

The expected outcomes are that the patient with TB will have Resolution of the disease Normal pulmonary function Absence of any complications No further transmission of TB

Etiology and Pathophysiology 2

The formation of a granuloma is a defense mechanism aimed at walling off the infection and preventing further spread. Most immunocompetent adults infected with TB are able to completely kill the mycobacteria. Some people contain the mycobacteria in a non-replicating dormant state. Of these individuals, 5% to 10% will go on to develop active TB infection when the bacteria begin to multiply months or years later.

Planning

The overall goals are that the patient with TB will: comply with the therapeutic regimen, have no recurrence of disease, have normal pulmonary function, and take appropriate measures to prevent the spread of the disease.

Diagnostic Studies 1

The tuberculin skin test (TST) (Mantoux test) using purified protein derivative (PPD) is the standard method to screen people for M. tuberculosis. The test is administered by injecting 0.1 mL of PPD intradermally on the ventral 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. Induration, a palpable, raised, hardened area or swelling (not redness) at the injection site means the person has been exposed to TB and has developed antibodies. (Antibody formation occurs 2 to 12 weeks after initial exposure to the bacteria.)

Implementation

The ultimate goal is to eradicate TB worldwide. Screening programs in known risk groups are of value in detecting individuals with TB. Treatment of LTBI reduces the number of TB carriers in the community. The person with a positive tuberculin skin test should have a chest x-ray to assess for the presence of active TB disease. Individuals with a diagnosis of TB must be reported to the public health authorities for identification and assessment of contacts and risk to the community. Programs to address the social determinants of tuberculosis are necessary to decrease transmission of TB. Reducing poverty, over-crowded living conditions, malnutrition, smoking, and drug/alcohol abuse can help minimize TB infection rates. Improving access to health care and education is also important.

Drug Therapy for Active Disease 1

Treatment is aggressive: Two phases of treatment Initial (8 weeks) Continuation (18 weeks) Four-drug regimen: Isoniazid, Rifampin (Rifadin), Pyrazinamide, Ethambutol Remember: RIPE

Diagnostic Studies 2

Tuberculin skin test (TST) Positive if ≥1.`5 mm induration in low-risk individuals Response ↓ in immunocompromised patients Reactions ≥5 mm considered positive Two-step testing recommended for health care workers getting repeated testing and those with decreased response to allergens Two-step testing ensures future positive results accurately interpreted

Tuberculosis

Tuberculosis (TB) usually involves the lungs, but any organ can be infected including brain, kidneys, and bones. CDC reports that more than 2 billion people are infected with TB. The incidence of TB worldwide declined until the mid-1980s when HIV disease emerged. The major factors that contributed to the resurgence of TB were (1) high rates of TB among patients with HIV infection (2) the emergence of multidrug-resistant (MDR) strains of M. tuberculosis. Although the prevalence of TB has increased in Europe, it has steadily declined in the United States since reaching a resurgence peak in 1992.

Drug Therapy for Latent TB

Usually treated with Isoniazid for 6 to 9 months HIV patients should take Isoniazid for 9 months Alternative 3-month regimen of Isoniazid and rifampin OR 4 months of rifampin