| Slide 19. Primary Anti-TB Drug Resistance, United States, 1993–2009. Primary drug resistance is shown
for the past 17 years. The graph starts in 1993, the year in which the individual TB case reports submitted to
the national surveillance system began collecting information on initial susceptibility test results for patients
with culture-positive TB. Data were available for more than 85% of culture-positive cases for each year.
Primary resistance was calculated by using data from persons with no reported prior TB episode. Resistance
to at least isoniazid remained between 7.0% and 8.6%. However, resistance to at least isoniazid and rifampin,
known as multidrug-resistant TB (MDR TB), decreased from 2.5% in 1993 to 1.1% in 1997, and remained at
approximately 1.0 % up to 2009 when it increased to 1.2%.
2009 Surveillance Slides Main