For skin testing, the preferred antigen is purified protein derivative (PPD) of intermediate strength of 5 tuberculin units. If the intracutaneously applied test result is negative, no further evaluation is needed. A positive skin test result measures �5 mm in diameter and requires evaluation for active disease, including a chest radiograph.
Two IGRAs are available: QuantiFERON-TB Gold and T-SPOT TB tests are recommended by the CDC (2005a,b) for the same indications as skin testing. Although these tests have not been evaluated as extensively as tuberculin skin testing, Kowada (2014) concluded that the tests are cost efective.
Other essential laboratory methods for detection or verification of infection-both active and latent-include microscopy, culture, nucleic acid amplification assay, and drug-susceptibility testing (Horsburgh, 2015; Raviglione, 2015).
Latent Infection. In nonpregnant tuberculin-positive patients with latent infection who are younger than 35 years and who have no evidence of active disease, isoniazid, 300 mg orally daily, is given for 9 months. Isoniazid has been used for decades, and it is considered safe in pregnancy (Briggs, 2015; Taylor, 2013). Compliance is a major problem, and Sackof (2006) and Cruz (2005) and their associates reported a disappointing 10-percent treatment completion. One obvious disconnect is that care for tuberculosis is given in diferent health systems than prenatal care (Zenner, 2012). hese observations are important because most recommend that isoniazid therapy be delayed until ater delivery. Because of possibly increased isoniazid-induced hepatitis risk in postpartum women, some even recommend withholding treatment until 3 to 6 months ater delivery. hat said, neither method is as efective as antepartum treatment to prevent active infection. Boggess and colleagues (2000) reported that only 42 percent of 167 tuberculin-positive asymptomatic women delivered at San Francisco General Hospital completed 6-month therapy that was not begun until the irst postpartum visit.
There are exceptions to delayed treatment for latent infection in pregnancy. Known recent skin-test convertors are treated antepartum because the incidence of active infection is 5 percent in the first year (Zumla, 2013). Skin-test-positive women exposed to active infection are also treated because the incidence of infection is 0.5 percent per year. Finally, HIVpositive women are treated because they have an approximate 10-percent annual risk of active disease.
Active Infection. Recommended initial treatment for active tuberculosis in pregnant women is a four-drug regimen with isoniazid, rifampin, ethambutol, and pyrazinamide, along with pyridoxine. For meningitis, levoBoxacin may be added (Kalita, 2014). In the irst 2-month phase, all four drugs are givenbactericidal phase. his is followed by a 4-month phase of isoniazid and rifampin-continuation phase (Raviglione, 2015; Zumla, 2013). A few reports describe MDR-TB during pregnancy, and treatment options have been reviewed (Horsburgh, 2015; Lessnau, 2003). Breastfeeding is not prohibited during antituberculous therapy.