36: Tuberculosis: Assessment, Analysis, and Associated Dental Management Guidelines

36

Tuberculosis: Assessment, Analysis, and Associated Dental Management Guidelines

TUBERCULOSIS EPIDEMIOLOGY

Mycobacterium tuberculosis (MTB) is an aerobic, acid-fast bacillus that usually affects the lungs. There has been an increased incidence of MTB secondary to HIV, homelessness, and emigration. Ninety percent of the adult cases of tuberculosis (TB) are due to reactivation of a dormant infection.

RISK FACTORS

Risk factors for TB are HIV; diabetes; prolonged steroid use; alcoholism; immunosuppressive treatment; and being a prisoner, nursing-home resident, or healthcare worker; and close contact with infectious patients, underweight patients, and persons from countries with a high TB prevalence.

TRANSMISSION

TB is spread from person to person through the air via coughed-infected droplets. Coughed-up, aerosolized particles stay around for a long time and infect susceptible individuals.

SYMPTOMS AND SIGNS

Symptoms and signs frequently associated with TB are fever, chest pain, chills, cough, weight loss, hemoptysis, night fever, night sweats, and fatigue.

DIAGNOSIS

The diagnosis of TB is made with:

1. The Tuberculin skin test (TST): The TST is done using purified protein derivative (PPD) from Mycobacterium tuberculosis. The PPD skin test is a delayed hypersensitivity reaction that shows response in 48–72 hours. The response is indicated by an induration or thickening at the site of the inoculum that is measured to identify if the reaction is positive or negative (Table 36.1).
2. QuantiFERON TB Gold test (QFT-G): The QFT-G is a new test for diagnosing latent M. tuberculosis infection. It is an in vitro diagnostic test that measures a component of cell-mediated immune reactivity to M. tuberculosis.
The test is based on the quantification of interferon-gamma (IFN-γ) released from sensitized lymphocytes in whole blood incubated overnight with purified protein derivative (PPD) obtained from M. tuberculosis. The QFT-G can be used in place of the TST.
3. Sputum smear and culture: The bacteria, when cultured, can take 3–6 weeks to grow.
4. Chest x-ray: The chest x-ray can show hilar adenopathy, upper-lobe infiltrates, pleural effusion (especially in young patients), and calcifications. The chest x-ray is done if the PPD is positive. If the chest x-ray is abnormal, the patient is evaluated for active TB.

Table 36.1 Interpretation of a Positive TST PPD Reaction

Induration Size At-Risk Populations
5mm induration: A 5mm reaction is positive in:

  • An immune-compromised patient
  • A close contact of a patient with TB
10mm induration: A 10mm reaction is positive in:

  • Recent migrant to the Unites States
  • An IV drug user
  • A patient less than 4 years old
15mm induration: A 15mm reaction is positive in:

  • One with no known TB risk factors

WHEN TO INITIATE TB TREATMENT

Treatment for TB should be initiated with the presence of a positive AFB smear or when there is a high clinical suspicion.

TYPES/FORMS OF TB

The three forms of TB are:

  • Latent TB
  • Active TB/Pulmonary TB
  • Multidrug-Resistant (MDR) and Extensively Drug-Resistant (XDR) TB

Latent TB

With latent TB the patient has a positive skin test; negative chest x-ray; and no symptoms, signs, or physical findings of TB. The patient is treated to prevent future reactivation to the active form of TB.

Active TB/Pulmonary TB

A patient is said to have active/pulmonary TB when the patient has a positive skin test; the chest x-ray may be abnormal; the patient experiences fever, cough, night sweats, hemopytosis, anorexia, and weight loss; and the respiratory specimen smear test is positive.

Multidrug Resistant (MDR) and Extensively Drug-Resistant (XDR) TB

The four-drug standard regimen, or the first-line, anti-TB drugs, when used correctly can successfully treat TB. When these drugs are used incompletely, incorrectly, or not at all, multidrug-resistant TB (MDR-TB) can develop. Drug-resistant TB is a dangerous form of TB caused by the TB bacillus becoming resistant to at least isoniazid and rifampicin, the two most powerful anti-TB drugs. MDR-TB takes longer to treat with second-line drugs and the care is often expensive. Extensively drug-resistant tuberculosis (XDR-TB) develops when the second-line drugs are also incompletely or inappropriately used, such that they become ineffective. Treatment options for XDR-TB are even more restrictive and expensive because the patient has severe resistance to the first and second line of TB treatment.

Latent TB Treatment

New CDC guidelines for managing latent tuberculosis infection (LTBI): Tuberculosis can be prevented by treating latent Mycobacterium tuberculosis infection (LTBI). Studies have shown that a new combination of isoniazid (INH) and rifapentine (RPT) given once-per-week for 12 weeks, as directly observed therapy (DOT) to otherwise healthy people ages 12 and older who are at high risk for developing TB, is very effective in preventing TB. The new INH-RPT DOT regimen is beneficial for use in correctional institutions and homeless shelters.

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Jan 4, 2015 | Posted by in General Dentistry | Comments Off on 36: Tuberculosis: Assessment, Analysis, and Associated Dental Management Guidelines
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