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Warning:
This site is being maintained for historical purposes, but has had no new entries since October 1998. To find more recent articles, please visit the following:
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SYNOPSIS: Current Guidelines For M. tuberculosis Testing
U.S Department of Health and Human Services, Public Health Program, Centers for Disease Control, Public Health Program Office
Publication date: 01/01/1990
Table of Contents
Synopsis: Current guidelines for M. tuberculosis testing
The recommended rapid testing systems currently available are
Recommended managerial practices include
Table 1, Testing Practices
POINT OF CONTACT FOR THIS DOCUMENT:
Tables
Testing Practices
Synopsis: Current guidelines for M. tuberculosis testing
The recommendations of the American Thoracic Society should be followed to determine if a laboratory should do mycobacterial testing. The recommendations are as follows:The testing systems and managerial practices selected by a laboratory should be those that contribute to achieving a rapid turnaround time for isolating, identifying, and drug susceptibility testing M. tuberculosis. Using currently available systems, it is possible to achieve a turnaround time of 3 weeks from collection of the specimen to reporting results of susceptibility testing with primary drugs.
- To maintain proficiency in acid-fast (AFB) microscopy, a minimum of 10 specimens per week should be examined.
- To maintain proficiency in culture and identification, 20 specimens per week should be digested and cultured.
The recommended rapid testing systems currently available are
Comment: Only the BACTEC radiometric system is available at this time. Other systems, however, are currently being evaluated and may be available shortly.
- AFB Microscopy: Fluorochrome-staining
- Isolation: Liquid media
Identification:
Drug Susceptibility Testing: Primary drugs--streptomycin, isoniazid, rifampin, ethambutol, pyrazinamide--in liquid medium (BACTEC system).
- BACTEC/NAP
- Genetic probe assays
- HPLC (suitable for reference laboratories only)
Comment: No reliable system using liquid media is currently available for testing secondary drugs.
Recommended managerial practices include
Laboratory Profile: A MODEL 20-200 Clinical Specimens per Week
- Immediate testing of specimens and isolates; no daily holdovers for batching.
- Immediate telephoning of significant results to clinicians/physicians at each stage of the testing process.
Managerial Practices:
- Determines that the laboratory receives a sufficient number of specimens or cultures to maintain proficiency in each test offered.
- Maintains effective communication (via telephone and in writing) with clinicians in matters pertaining to specimen collection and transport.
- Telephones clinicians immediately with test results; confirms with a written report.
- Processes specimens immediately upon receipt.
- Starts drug testing immediately upon identification of an isolate as M. tb. (does not hold for batching).
- Provides partial to full laboratory coverage over weekends and holidays.
- Knows when it is more prudent to send specimens and/or cultures to another laboratory for testing.
- Works with other laboratories in the area for all to achieve the fastest turnaround time possible.
Table 1, Testing Practices
Table 1
POINT OF CONTACT FOR THIS DOCUMENT:
To request a copy of this document or for questions concerning this document, please contact the person or office listed below. If requesting a document, please specify the complete name of the document as well as the address to which you would like it mailed. Note that if a name is listed with the address below, you may wish to contact this person via CDC WONDER/PC e-mail.
ROBERT C GOOD
PUBLIC HEALTH PRACTICE PROGRAM OFFICE
CDC (PHPPO)
1600 Clifton Rd NE, MS:(C-09)
Atlanta, GA 30333
Table 1
Table 1. Testing Practices ============================================================================================= Clinician Elapsed Time Laboratory(a) --------------------------------------------------------------------------------------------- Collects specimen 0 Receives results of AFB Day 1 to Day 2 -Receives specimen microscopy -Concentrates specimen -Evaluates fluorochrome-stained smear -Inoculates BACTEC culture medium(b) -(Inoculates drug(c) susceptibility medium w/AFB POSITIVE specimens)(d) Day 2 to Day 10 -Incubates and monitors cultures Receives culture and ID Day 11 to Day 21 -Detects growth in culture medium test results on positive -Test growth w/probes specimens -Inoculates BACTEC drug susceptibility medium Receives drug Day 15 to Day 28 -Obtains drug susceptibility results susceptibility results --------------------------------------------------------------------------------------------- (a) Events in each frame occur within a 24 hour period. (b) Solid media is also inoculated as backup (c) Primary Drugs = streptomycin; isoniazid (INH); rifampin; ethambutol; pyrazinamide (PZA) Secondary Drugs = ethionamide; kanamycin; capreomycin; D-cycloserine; rifabutin; ciprofloxacin; amikacin (d) Theoretically, direct drug testing ideal; realistically, dependibility of results variable ==============================================================================================
