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Region I Laboratory UpdateCDC National Infertility Prevention Project
Boston, MassachusettsNovember 15, 2010
Richard Steece, Ph.D., D(ABMM)
Laboratory Consultant
CDC National Infertility Prevention [email protected]
Laboratory Update
1. CDC Laboratory Guidelines for
CT/GC and Syphilis
Guidelines for the Laboratory Detection of Chlamydia trachomatis and Neisseria
gonorrhoeae Testing
Recommendations from the expert consultation meeting
January 13-15, 2009
Key Questions (CT/GC)
• Performance Characteristics– All culture and non-culture tests may generate
false-positive and false-negative results– Nucleic acid amplification tests (NAATs) have
superior performance to all other tests– Culture is still useful in certain circumstances
• GC susceptibility testing– Serology
• Should not be used for the Dx of non-LGV CT infections
Key Questions (CT/GC)
• Screening Applications– Vaginal swabs are the optimal specimen type
for use with NAATs• Vaginal swab and urine specimens are not intended to replace
cervical exams and endocervical specimens for the Dx of female urogenital infections
– Urine is the preferred specimen type for testing males with NAATs
– NAATs have superior performance to culture for the detection of rectal CT and GC infections and for the detection of pharyngeal GC infections• NAATs are not cleared for rectal and pharyngeal specimens by
the FDA
Key Questions (CT/GC)
• Laboratory Confirmation– Routine repeat testing of NAAT positive
specimens is not recommended for CT– Routine repeat testing of NAAT positive
specimens is not recommended for GC unless there are a significant number of false-positive test results, in clinical studies, due to cross-reaction with non-gonococcal Neisseria species
– Medico-legal issues (ASM Symposia 05-2010)• Data supports the use of NAATs in adult cases of sexual
abuse• Limited data on the use of NAATs in cases involving
children
CDC Syphilis Testing Guidelines
Recommendations from the expert consultation meeting
January 13-15, 2009
Key Questions (Syphilis)
• Direct Detection of T. pallidum (Tp)– Darkfield Microscopy– Immunostaining– Nucleic Acid Amplification Tests
• Congenital Syphilis– A reactive IgM test may be useful and should be used in
conjunction with direct detection– A four-fold or greater ratio of neonatal to maternal titers is
rarely useful• Neurosyphilis
– Neurosyphilis cannot be diagnosed serologically– The use of VDRL in evaluating CSF may still be worthwhile
• Serology
Serology Testing (Syphilis)
• Non-treponemal tests– RPR, VDRL, TRUST
• Treponemal tests– FTA-ABS, TP-PA– EIA, CLIA, Microsphere
• Point of Care tests– None available in U.S.
Non-Treponemal Screening
PROS• High Sensitivity• Low cost• Does not detect past
infections• Requires little equipment
for testing• Usually requires only one
reflex test• Useful for treatment
monitoring
CONS• Lower specificity• Labor-intensive• Subjective results• Manual data
manipulations
Treponemal ScreeningPROS• High Sensitivity• High Specificity• Objective results• Automation / high
throughput• Interface with LIS
CONS• Cannot distinguish between
active and previously treated disease
• Potential for over diagnosis and over treatment
• May require more resources for EPI/DIS investigations
• Specific, potentially costly instrumentation
• May require multiple reflex tests for resolving discrepants
Titer
NonreactiveNot syphilis (or early Not syphilis (or early
syphilis)syphilis)
Reactive
Treponemal TestFTA-ABS, TP-PA
ReactiveSyphilis - Treat
Non-Treponemal TestRPR, VDRL, TRUST
Traditional Testing Algorithm Using Non-Treponemal
Initial Screen
NonreactiveFalse positive
Non-Treponemal Test
Pope Infect Med 2004
A2 Quantitative Nontreponemal (i.e. RPR)
A1-Negative for Syphilis
antibodies
A1+
A3 Treponemal Test that uses a different antigen
or platform from A1 (i.e. TPPA, FTA)
A1+ A2+Consistent with Syphilis
(past or current infection)
A1+ A2-
A1+ A2- A3+Possible Syphilis infection; Requires further historical
and clinical evaluation
A1+ A2- A3-Unconfirmed EIA; Unlikely to be Syphilis; If patient is at risk for syphilis, re- test in 1 month
A1Syphilis EIA or CLIATesting
Algorithm Using EIA or CLIA as Initial Screen
* Laboratory should report the results of all three assays (if applicable) within 7 days
Guidelines for the Laboratory Detection of Chlamydia trachomatis and Neisseria gonorrhoeae
andSyphilis Testing Guidelines
Next Steps– Proceedings from the Expert Consultation Meetings is
available on the APHL website• www.aphl.org/aphlprograms/infectious/std/Documents/CTGCL
abGuidelinesMeetingReport.pdf– Publish the entire revised laboratory guidelines
document as a Reports and Recommendations supplement in MMWR
• Targeted for late 2010
The End
Questions?