Understanding and Managing Latent TB Infection Arnold, Missouri October 5, 2010 Testing to TB Infection Using the TST Presented by Debra Howenstine, MD for Debbie Onofre, RN October 5, 2010 Tuberculin Skin Testing Debbie Onofre, BSN, RN Heartland National TB Center October 5, 2010
Objectives Discuss Mantoux Tuberculin Skin Testing Purpose of Targeted Skin Testing Administering and reading the TST Utilizing the TB Questionnaire Purpose of Targeted Skin Testing Strategy for controlling and preventing TB by identifying persons with: TB disease Contact to TB cases Screen persons at HIGH risk for LTBI and TB disease
Persons at High Risk Recently Infected Progression greatest in first 1-2 yrs after exposure Medical Conditions that increase risk of progression from LTBI to TB Disease Medical Conditions That Increase Risk for Progression to Active TB HIV infection Age < 5 years Silicosis Diabetes mellitus Chronic renal failure Transplant patients Malnutrition Immunosuppressive therapy TNF-a blockers History of gastrectomy or jejunoileal bypass Cancers (lung, lymphoma, leukemia
Determining Positivity: ATS/CDC Cut Points > 5 mm is considered positive in persons who are: Close contacts of infectious TB cases (known or suspected) HIV-infected persons (known or suspected) Fibrotic changes on CXR consistent with prior TB Patients with organ transplants and/or those receiving Immunosuppressed treatments Clinical evidence of TB disease Determining Positivity: ATS/CDC Cut Points > 10 mm is considered positive in: Recent immigrants to the U.S. (<5years) from TB endemic countries Illicit drug users Mycobacteriology lab workers Residents of high risk congregate settings Children <4 years old Persons with medical conditions that place them at risk for TB
Determining Positivity: ATS/CDC Cut Points > 15 mm is considered positive in: Persons with no risk factors for TB Targeted skin testing programs should only be conducted among high-risk groups the decision to test is a decision to treat
Proven Method for Identifying LTBI Mantoux Test PPD: (purified protein derivative) TST: (TB skin test) TST Placement Select tuberculin syringe Draw up 0.1 ml of PPD Choose site free of scars, tattoos, or abrasions (L forearm) Intra-dermal injection Insert at a 15 degree angle Bevel up Produce wheal of 6 to10 mm Always follow standard precautions
FAQ: How Soon May I Repeat a TST If Initial Placement Is Incorrect? Immediately Place 2 inches from original site or on other arm Administering the TST
Incorrect TST Placement After Placement of TST Record the date, time, and location of TST Instruct patient not to scratch the site, but use cool compress to relieve any itching or swelling Inform patient of importance of returning for reading of TST within 48-72 hours (2-3 days) appointment card for TST reading may be helpful
FAQ: What Do We Do If Client Returns After 72 hours? If TST is positive measure and record induration in millmeters If TST is read as negative, repeat TST at this time Reading TST Reactions Read 48-72 hours after placement Palpate for induration Determine borders Measure induration only
Determine Borders Measuring Induration
Measure Induration not Erythema Recording Result of TST Record date and time of reading and name of person reading TST Record in millimeters (mm) No reaction should be written as 00 mm
Host Factors Recent TB infection (< 3 months) Anergy (HIV) Very young age (<6 months old) Other viral, bacterial, fungal infections Live virus vaccinations Overwhelming TB disease False Negative Reactions Technical factors Incorrect method of administration; Incorrect interpretation; Improper storage or contamination False Positive Reactions Vaccination with BCG Used in countries with high prevalence of TB Used to prevent Tb meningitis and miliary TB Reactions wane 5-10 years after inoculation Do not alter interpretation of TST reaction due to history of BCG. Infection with NTM (non-tuberculosis mycobacteria)
Evaluate Further Positive Skin Test Rule Out TB Disease CXR TB Symptom Screen/ Assessment MD Evaluation Sputum Collection Negative Skin Test Provide Documentation of result No further evaluation necessary
Storage and Handling of PPD Date and initial when vial is opened Store at 35-46 F in refrigerator or cooler with ice packs Do not store on door of refrigerator Store for 30 days after opening then discard Keep out of light Do not freeze Avoid pre-filling syn Utilization of the TB Questionnaire Quick tool to help determine if individuals have signs or symptoms suggestive of TB For anyone requesting a skin test Contacts Persons targeted for screening (high-risk groups) Walk-ins Determines risk prior to testing Provides a symptom review to prior history of TB Infection or disease
TB Screening for Children Recommendations from the CDC and AAP: Only children in high risk populations be tested Universal testing in schools, camps, daycares is NOT recommended Instead, a universal questionnaire to determine risk for TB infection should be utilized FAQ: Can Infants Be Tested? YES - Infants may not react to a TST before 6 months of age, but should be tested if there is risk of exposure
FAQ: Can Pregnant Women Be Tested? YES No risk to mother or fetus. Pregnancy is often a good time to screen and test women who are at risk of TB FAQ: Can A Person With A Previous Positive TST Be Re-Tested? Yes Retesting is not necessary if the previous result was documented Repeated skin tests do not sensitize or make persons allergic to tuberculin
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