Latent <em>Mycobacterium tuberculosis</em> Infection and Laboratory Test Methods
Continuing Education Credits
This course provides information about the difference between active tuberculosis (TB) disease and latent tuberculosis infection (LTBI), etiology, pathogenesis, and distribution both in the US and globally. Targeted testing of individuals (based on risk factors), as well as laboratory testing methods (to include the tuberculin skin test [TST] and interferon gamma release assay [IGRA]) are described. An emphasis on laboratorian troubleshooting of aberrant results is included. The course concludes with a brief description of recommended treatment and management regimens for LTBI (including the role of laboratory in the monitoring of infected individuals).
Objectives
- Explain the difference between active tuberculosis (TB) disease and latent tuberculosis infection (LTBI).
- Describe the etiology and pathogenesis of TB disease and LTBI.
- Summarize the epidemiology of TB disease and LTBI in the United States and globally.
- Describe targeted testing and who should be tested for TB infection.
- Examine recommended TB test methods, interpretations, and limitations.
- Discuss recommended treatment and management regimens for patients with LTBI.
Course Outline
- Introduction
- Introduction
- Historical Background
- What is the Difference Between Latent and Active TB?
- Terminology
- List of Terms and Abbreviations
- Which of the following statements is correct regarding LTBI?
- Select the statement that best corresponds to the abbreviation IGRA.
- Etiology and Pathogenesis
- Etiology
- Pathogenesis of Active Tuberculosis
- Pathogenesis of Latent Tuberculosis
- Risk of Activation from Latent to Active Tuberculosis
- In LTBI:
- Expected laboratory findings in a case of latent tuberculosis infection (LTBI) might be:
- True or False: The risk of activation from latent tuberculosis infection (LTBI) to active tuberculosis (TB) disease is approximately 17–20% over an individual's lifetime.
- Epidemiology
- Epidemiology
- TB and LTBI in the United States
- TB and LTBI in the World
- Special Consideration for HIV Positive Patients
- At present, the prevalence of LTBI (people living with TB infection) in the United States is estimated to be as high as:
- True or False: It is estimated that half of the world's population has latent TB infection (LTBI).
- Targeted Testing
- Targeted Testing: Who Should be Tested for TB Infection?
- Targeted Testing: Who Should be Tested for TB Infection? (continued)
- Special Consideration: Individuals Vaccinated with Bacille Calmette-Guerin Vaccine
- Persons at high risk for TB infection fall into which two broad categories?
- Which statement best reflects people at high risk for TB infection or TB disease after infection?
- Test Methods
- Test Methods
- Additional Considerations
- Troubleshooting Unusual Results
- Tuberculin Skin Test
- Tuberculin Skin Test
- Tuberculin Skin Test Procedure
- Tuberculin Skin Test Frequency
- TST Interpretation of Results
- TST Interpretation of Results, continued
- Tuberculin Skin Test Limitations
- A false-positive TST may occur when:
- Which of the following statements is correct when describing the TST procedure?
- Interferon Gamma Release Assay
- Interferon Gamma Release Assay Description
- IGRA Procedure
- IGRA Procedure, continued
- IGRA Interpretation of Results
- IGRA Limitations
- Which of the following is true of current IGRA test methods for determining TB status?
- The interferon gamma release assay (IGRA):
- Treatment and Management
- Recommended Treatment Regimens for LTBI
- Recommended Patient Management Regimen for LTBI
- In Summary
- Duration of drug treatment for LTBI may be as short as three months or as long as:
- Patient management for individuals on drug treatment for LTBI include:
- References
- References
Additional Information
Level of Instruction: Intermediate
Intended Audience: Medical laboratory scientists, medical
laboratory technicians, microbiology staff, laboratory supervisors, and laboratory managers. This
course is also appropriate for MLS and MLT students and pathology residents.
Author Information: Dr. Julie Ann West is certified by the American Society for Clinical Pathology (ASCP) as a Medical Laboratory Scientist (MLS) and as a Specialist in Microbiology (SM). In addition, Dr. West has earned a PhD in Public Health - Infectious Disease Epidemiology and is Certified in Public Health (CPH) by the National Board of Public Health Examiners. Dr. West is experienced as a Technical Specialist, Safety Officer, Educator, and Lead in the Veterans Administration Healthcare System and has prior experience as an Administrative Laboratory Director.
The author has no conflict of interest to disclose.
Reviewer Information:
Christine Mayambala, PhD, is certified by the American Society for Clinical Pathology (ASCP) as a Medical Laboratory Scientist (MLS). She has earned a PhD in Public Health - Epidemiology Specialization. Dr. Mayambala is experienced as a Generalist and Molecular Technologist. Dr. Mayambala has taught pre-nursing and medical laboratory technology at a community college in Metro Atlanta.
Laurie Bjerklie, MA, MLS(ASCP)CM, is
a Lead Education Developer. She earned a B.S. in Medical Laboratory Science
from the University of North Dakota and an M.A. in Curriculum and Instruction
from Saint Xavier University. She has over 15 years of experience in higher
education and has held program director and faculty positions in both MLT and
MLS programs.
Course Description: This course provides information about the difference between active tuberculosis (TB) disease and latent tuberculosis infection (LTBI), etiology, pathogenesis, and distribution both in the United States and globally. Targeted testing of individuals based on risk factors, as well as laboratory testing methods, including the tuberculin skin test (TST) and interferon gamma release assay (IGRA), are described. An emphasis on laboratorian troubleshooting of aberrant results is included. The course concludes with a brief description of recommended treatment and management regimens for LTBI.