The Commonwealth of Massachusetts
Executive Office of Health and Human Services
Department of Public Health
William A. Hinton State Laboratory Institute
305 South Street, Jamaica Plain, MA 02130

DEVAL L. PATRICK
GOVERNOR
TIMOTHY P. MURRAY
LIEUTENANT GOVERNOR
JUDYANN BIGBY, MD
SECRETARY
JOHN AUERBACH
COMMISSIONER	

TO: 	Providers submitting specimens for Chlamydia trachomatis and Neisseria gonorrhoeae nucleic acid amplification testing (NAAT)

FROM: 	Linda Han, MD, MPH				
Director, Bureau of Laboratory Sciences			

Katherine Hsu, MD, MPH 
Medical Director, Division of STD Prevention 
Bureau of Infectious Disease
 
RE: 	Transition to new NAAT technology

DATE: 	January 10, 2011
________________________________________________________________________

On February 1, 2011, the MA Department of Public Health STD Laboratory will begin using a new nucleic acid amplification testing (NAAT) technology for Chlamydia trachomatis and Neisseria gonorrhoeae detection.  The new method (the BD Qx assay) has a greater sensitivity and specificity relative to the method currently in use (BD ET assay), and minimizes the likelihood of false positive results attributable to specimen contamination.  Furthermore, the new assay does not produce results that are interpreted as “inconclusive.” 

Effective February 1, 2011, endocervical swabs, male urethral swabs, and urine specimens must be submitted in new Qx NAAT tubes.  Endocervical, urethral, and urine samples submitted in the old ET tubes after February 1, 2011 will be rejected. Rectal swab specimens must continue to be submitted in the old ET tubes.  Rectal swabs submitted in Qx tubes will be rejected.  

In the next several weeks, you will be receiving new Qx endocervical and male urethral swab collection kits, as well as new Qx urine tubes.  Detailed specimen collection and submission instructions are attached.  After February 1, 2011, please discard all unused ET urine tubes and, if your site does not submit rectal swab specimens, also discard all old ET swab collection kits.  

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In spite of the improved performance of the new assay, providers should remember that no laboratory test is perfect.  The positive predictive value of any laboratory test is highly dependent on the prevalence of the disease for which the test is being performed.  When tests are used to identify diseases that are relatively uncommon in a patient population, the likelihood that a positive test result is falsely positive can be high.  All laboratory test results should therefore be interpreted in the context of the risk profile and clinical findings of each patient.

If you have further questions regarding CT/NG NAAT at the MA DPH STD Laboratory, please contact the STD Laboratory supervisors (Jamie Holland at 617-983-6614, or Arthur Kazianis at 617-983-6372).  Thank you for your assistance during this transition.