Chapter 66 TB is an infection that has been known for centuries. Reactivation disease occurs in a patient who was infected in the past. When the patient becomes old or immunocompromised, the disease may reactivate. This can occur in a patient with COPD who is taking prednisone (see Box 66-1 for risk factors for TB). Criteria used for interpretation of the PPD are listed in Box 66-2. The test should be read 48 to 72 hours after the injection is given. Positive reactions may still be measurable up to 1 week after testing. If the patient returns after more than 3 days and the results appear negative, the test must be repeated. The test site is measured crosswise to the axis of the forearm. Only the induration (hardness) is measured. Erythema is not measured. The result is recorded in millimeters, not as positive or negative. Candidates for testing include all high-risk patients (as indicated in Box 66-1) plus employees or residents in congregate settings, such as hospitals, prisons and jails, homeless shelters, and nursing homes, or people from areas of the world with a high prevalence of TB. Close contacts of someone with infectious TB who has a negative PPD should be retested 10 weeks after the contact. Previously, it was taught that the clinician should never give a PPD to a patient who had received a bacille Calmette-Guérin (BCG) vaccination. However, previous vaccination with BCG usually should not influence the need for tuberculin skin testing. Most patients who have received BCG have been told that they must never have a PPD because of the risk for a serious adverse reaction, thus they will refuse the PPD. Previous vaccination with BCG does not change the need for treatment or testing. Patients who are immunocompromised should be evaluated for anergy prior to receiving the PPD. When a clinician elects to use anergy testing as part of a multifactorial assessment of a person’s risk for TB, FDA-approved methods include the Mantoux-method tests (e.g., mumps and Candida), which are used together and have cutoff diameters of 5 mm of induration (see http://www.cdc.gov/mmwr/preview/mmwrhtml/00049386.htm). Other protocols suggest that the mumps skin test antigen (MSTA) and tetanus toxoid (fluid) may be used. Give 0.1 ml of the antigen intradermally. Read at 48 to 72 hours. Any induration greater than 2 mm is considered positive (reactive), so PPD testing can proceed. Causes of a false-negative skin test include HIV, lymphoma, and recent live vaccinations. • Centers for Disease Control and Prevention, Division for Tuberculosis Elimination: Targeted tuberculin testing and interpreting skin test results and treatment of tuberculosis, CDC Fact Sheets (Available at www.cdc.gov/ nchstp/tb). • American Thoracic Society, Centers for Disease Control and Prevention, and the Infectious Diseases Society of America: MMWR 52(RR11):1-77, 2003 or reprinted in Treatment of tuberculosis, Am J Respir Crit Care Med 167:603, 2003. • Centers for Disease Control and Prevention, Morbidity and Mortality Weekly Reports, December 9, 2011. Available at http://www.cdc.gov/tb/topic/treatment/default.htm. • Centers for Disease Control and Prevention: Treatment of latent TB infection and TB disease. www.cdc.gov/tb. For patients with newly diagnosed pulmonary tuberculosis, a 6-month course of chemotherapy with at least two drugs is recommended. Several regimens are available. Each regimen has an initial phase, which includes three or four drugs given for 6 to 8 weeks, followed by a continuation phase, with two drugs given for 18 weeks. See Table 66-1. TABLE 66-1 CDC-Approved Basic TB Disease Treatment Regimens ∗EMB can be discontinued if drug susceptibility studies demonstrate susceptibility to first-line drugs. From Centers for Disease Control and Prevention: Treatment of latent TB infection and TB disease. www.cdc.gov/tb. Accessed 9-12-2012. • Isoniazid is the treatment of choice and is given for 3 months along with rifapentine. • In patients who are HIV infected, treatment generally begins as soon as TB is suspected and is modified according to the status of HIV disease. • In patients who are not HIV infected, treatment usually is reserved until a definitive diagnosis has been made. • Report all cases to local and state health authorities. • Test and treat close contacts. • Monitor closely to ensure that the patient is compliant and is responding to prescribed drugs. • DOT (direct observed therapy) has the highest success rate. • Administer multiple drugs to which organisms are susceptible. • Add at least two new antitubercular agents when treatment failure is suspected. It is important to clarify who should receive preventive treatment. See Box 66-3 for risk factors for progression of latent tuberculosis. Anyone who has a risk factor should be considered for treatment. • cycloserine, ethionamide, streptomycin, amikacin/kanamycin, capreomycin, p-aminosalicylic acid (PAS), levofloxacin, moxifloxacin, gatifloxacin
Antitubercular Agents
Class
Generic Name
Trade Name
Antituberculars
isoniazid (INH)
Generic
rifampicin (RIF)
Rifampin, Rifadin
rifabutin
Mycobutin
rifapentine
Priftin
pyrazinamide (PZA)
Generic
ethambutol HCl (EMB)
Myambutol
streptomycin (SM)
Generic
cycloserine
Seromycin
ethionamide
Trecator
p-aminosalicylic acid (PAS)
Paser
Aminoglycosides
amikacin/kanamycin
Generic
capreomycin
Capastat
Fluoroquinolones
levofloxacin
Levaquin
moxifloxacin
Avelox
gatifloxacin
Tequin
Therapeutic Overview
Pathophysiology
Disease Process
Assessment
Testing for Exposure to TB
Treatment Principles
Standardized Guidelines
Evidence-Based Recommendations
Preferred Regimen
Alternative Regimen
Alternative Regimen
Initial Phase
Daily INH, RIF, PZA, and EMB∗ for 56 doses (8 weeks)
Daily INH, RIF, PZA, and EMB∗ for 14 doses (2 weeks), then twice weekly for 12 doses (6 weeks)
Thrice-weekly INH, RIF, PZA, and EMB∗ for 24 doses (8 weeks)
Continuation Phase
Daily INH and RIF for 126 doses (18 weeks)
or
Twice-weekly INH and RIF for 36 doses (18 weeks)
Twice-weekly INH and RIF for 36 doses (18 weeks)
Thrice-weekly INH and RIF for 54 doses (18 weeks)
Cardinal Points of Treatment
Treatment of Latent Infection
Treatment of Active Infection
Treatment of Latent Tuberculosis
Treatment Options
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