For health care workers without a documented negative tuberculin skin test result in the past how many months should baseline testing use the two-step method?

The correct answer is based on the guidelines for tuberculosis (TB) screening for health care workers, which are designed to minimize the risk of TB transmission in health care settings. When a health care worker does not have a documented negative tuberculin skin test (TST) result within the last 12 months, the two-step method is recommended for baseline testing.

The two-step testing process involves administering a first TST and then a second TST 1 to 3 weeks after the first. This approach is particularly useful in identifying individuals who may have been infected with TB but did not react to the initial test due to an anergic response (a failure to mount an immune response to the test). By using the two-step method in this context, it allows for the identification of latent TB infections and ensures that health care workers are not unknowingly exposing patients to TB.

The 12-month timeframe is established in part due to the potential changes in a person's immune system's response over the course of a year and the risk of exposure that health care workers face. Following this timeline helps maintain a safe health environment and is a standard public health practice in this field.