3F 5 WHO/PAHO Collaborating Centre for Syphilis Serology Proficiency Testing Program at the CDC

Wednesday, June 11, 2014: 11:25 AM
Allan Pillay, PhD, Laboratory Reference & Research Branch, DSTDP, CDC, Atlanta, GA, Susan Kikkert, AB, LRRB, DSTDP, CDC, Atlanta, GA, Mary L. Kamb, MD, MPH, Division of STD Prevention, Centers for Disease Control and Prevention, Atlanta, GA, Nathalie Broutet, MD, PhD, Department of Reproductive Health and Research, WHO, Geneva, Switzerland and Kevin Karem, PhD, DSTDP, CDC, Atlanta, GA

Background: Proficiency in serological testing is essential to accurately diagnose syphilis. CDC administers a syphilis serology proficiency testing (PT) program worldwide in its role as a WHO/PAHO Collaborating Centre for STD Diagnostics and Surveillance.

Methods:CDC sends a serum panel of known results to 78 laboratories worldwide. Participating laboratories perform treponemal (TPPA, MHA-TP, TPHA, FTA-ABS, EIA) and non-treponemal (VDRL, USR, RPR) qualitative and quantitative tests, reporting results to CDC for analysis and feedback.

Results: In 2012, 51(65.4%) of the 78 laboratories reported PT results on at least one serologic test (third panel). Qualitative VDRL and RPR non-treponemal test results from responding laboratories were comparable to those of 3 CDC reference laboratories (Georgia PHL; the Texas Department of State Health Services; and the Syphilis Serology Laboratory, CDC) for most VDRL and RPR samples.  For the qualitative VDRL, scores averaged 98.7 %, with 1 of 31(3.2%) reporting laboratories failing. Scores for the qualitative RPR averaged 99.4%, with 1 of 36 (2.7%) laboratories failing. For the quantitative VDRL and RPR, low scores were due to reported titers being too high or too low. Scores for the quantitative VDRL averaged 94.1%, with 3 of 29(10.3%) laboratories failing. Scores for the quantitative RPR averaged 94%, with 6 of 32(18.8 %) laboratories failing. For treponemal tests, the 42 laboratories performing the MHA-TP, TPHA, or TPPA averaged 98.6%; 3 (7.2%) laboratories failed. For FTA-ABS, 22 laboratories averaged 100%. For the EIA-IgG test, 18 laboratories averaged 98.9% with 1 (5.6%) not achieving an acceptable result. 

Conclusions: Laboratories participating in the syphilis PT program do well in treponemal and qualitative non-treponemal testing. However, several had problems in quantitative non-treponemal tests suggesting training or other capacity building options may be beneficial. Criteria for PT program inclusion should be revisited due to lack of reporting from a number of laboratories.