Guide to the Application of Genotyping to Tuberculosis Prevention and Control

Applying Genotyping Results to Tuberculosis Control Practices

This chapter provides guidelines for interpreting and responding to new genotyping results as they are reported by the genotyping laboratories. Specifically, we will describe how new information about genotyping matches can be combined with information about epidemiologic links between patients with TB in order to identify chains of recent TB transmission and take appropriate action to stop transmission (or, in the case of a false-positive culture, to stop treatment for patients who were falsely diagnosed with TB). Possible action steps include expanding a contact investigation, conducting an outbreak investigation, performing a cluster investigation in order to search for epidemiologic links between patients with matching genotypes, and determining whether a specific report of a TB case resulted from a false-positive culture report. Figure 6.1 provides a graphical representation of the steps involved in the decision analysis of when to take possible action steps. Finally, we will discuss how genotyping data provide a powerful tool to monitor trends in TB transmission.

Chapter 5, Developing a TB Genotyping Program, described the critical components of a TB genotyping program and the key procedures that need to be established to collect and analyze genotyping and epidemiologic data. The current chapter will focus on using that data in a decision analysis in order to identify specific action steps to take to improve TB control practices.