Chlamydia and Gonorrhea Lab Update þBurning Questions þLaboratory Guidelines þCT Immunobiology Consultation The findings and conclusions in this presentation

Chlamydia and Gonorrhea Lab Update

Burning Questions

Laboratory Guidelines

CT Immunobiology Consultation

The findings and conclusions in this presentation are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention

Alternate Specimen Verification

Rectal and oropharyngeal swabs FDA clearance being pursued Establish an external specimen bank

Home collected vaginal swabs Interest but studies have not commenced (that I’m aware of)

Performance

Discreet packaging Must meet federal regulations for shipping diagnostic specimens Wet vs dry swabs

Greater temperature ranges than covered in the product insert

NOT FDA CLEARED What are the parameters for an off-label verification study? Need sound guidance

Considerations

Self-Obtained Vaginal Swabs in a Home Setting

Sensitivity of Different Specimens by Three Different Assays

Assay FCU Cx S-vag C-vag

TMA 72% 89% 93% 90%

PCR 84% 91% 91% 93%

LCR 98% 96% 98% 100%

Combined 81% 91% 93% 93%

FCU – first catch urine, Cx – endocervix, S-vag – self-collected vaginal swab, C-vag - Clinician collected vaginal swab. Schachter J, et al. JCM 41;2003:3784

Preliminary Vaginal Swab Mailing Kit

One Example of a Vaginal Swab Mailing Kit

(Gen-Probe® Vaginal Swab Transport Tube, Vaginal Swab, Inner Medical Specimen Transport Tube, Vaginal Swab Collection Instructions, Follow-up Questionnaire, and Mailing Can)

Mailing Can

Follow-up Questionnaire

Swab

Swab Specimen Transport Conditions for Commercially Available CT/GC NAATs

Test Swab Condition Transport Temperature

Time to Test

BD ProbeTec Dry (no liquid media) 2 to 27oC 4 to 6 days

GenProbe APTIMA(vaginal swabs FDA cleared)

Penetrable top tube containing specimen buffer

2 to 30oC Up to 60 days

Roche Amplicor Tubes containing Chlamydia culture medium (eg. M4, 2ST, Bartels, etc)

18 to 25oC Within 1 hour

2 to 8oC Up to 7 days

Less than -20oC Up to 30 days

Package Temperature during USPS Transit from St. Louis to New Orleans

Package placed in St. Louis USPS drop box July 22, 2005 and received at 2:30pm July 26, 2005 in New Orleans. Temperatures were recorded at 10 minute intervals.

Package Temperature during USPS Transit from Jackson to New Orleans

Package placed in Jackson USPS drop box July 29, 2005 and received at 2:00pm August 10, 2005 in New Orleans. Temperatures were recorded at 10 minute intervals.

20

25

30

35

40

45

50

6:01

6:53

7:45

8:37

9:29

10:2

1

11:1

3

12:0

5

12:5

7

13:4

9

14:4

1

15:3

3

16:2

5

17:1

7

18:0

9

19:0

1

19:5

3

20:4

5

21:3

7

22:2

9

23:2

1

Cel

siu

s

Time

Residential Mailbox and Outside Air Temperature

Mailbox

Outside Air

Temperature recorded at 1 minute intervals August 21, 2005.

APTIMA Test Result for Chlamydia trachomatis (Relative Light Units)

Initial Temperature / Duration

Final Temperature / Duration

Inoculum (Inclusion forming units)

24oC / 24 hours 37oC / 24 hours

10 1104 1102

103 1226 1115

105 1195 1087

In Vitro Assessment of Specimen Stability






10 1172 1124

103 1133 1114

105 1142 1115







10 1059 1023

103 1211 1951

105 1147 1113


Alternate Specimen Verification

Rectal and oropharyngeal swabs FDA clearance being pursued Establish an external specimen bank

Home collected vaginal swabs Interest but studies have not commenced (that I’m aware of)

APHL / CDC STD Steering Committee Workgroups to develop Verification Protocols Involve CMS (CLIA) Part of revised CDC Laboratory guidelines

LGV Testing

Specimens submitted to CDC in 2007 for the detection of LGV ompA genotyping (not serology)

Specimen Type Number Submitted (%)

Results

Unable to amplify (%)

CT Negative (%) CT Positive (%) LGV (%)

Rectal Swab 52 (85%) 8 (15%) 14 (27%) 25 (48%) 5 (10% of all or 20% of CT+)

Urethral Swab 7 (11%) 3 (43%) 0 4 (57%) 0

Urine 1 (2%) 0 0 1 0

Unknown 1 (2%) 0 0 1 0

Importance of differentiating LGV from non-LGV rectal CT infections Course of recommended Tx varies

No commercial differential test available

Seems that settings that have been testing for rectal CT infections and managing those infections as non-LGV have not seen increases in proctocolitis

• Refer to Dr. Mark Pandori’s presentation at the 2008 STD Prevention meeting

Sx and Asx infections reported

CDC does not have a survelliance program LGV• Submission of specimens for reference testing should be based on local descions

Serology for rectal LGV testing No data

LGV Testing

Laboratory Guidelines

Background 1982

Laboratory Diagnosis of Chlamydia trachomatis Infections Isolation and serology

1993 Recommendations for the Prevention and Management of

Chlamydia trachomatis Infections• Isolation• Non-culture tests

Immunoassays, nucleic acid hybridization tests• Screening• Sexual assault• Presumptive Laboratory Diagnosis

Screening Tests to Detect Chlamydia trachomatis and Neisseria gonorrhoeae

Infections - 2002

Guideline Development CDC identified questions reviewed published literature from 1990 - 2000 prepared tables of evidence drafted recommendations

External consultants asked to review the drafted recommendations• selected on the basis of expertise and/or disciplinary or organizational

affiliations

CDC considered all suggestions from external consultants and finalized recommendations

Revising Laboratory Guidelines for the Detection of Chlamydia trachomatis and Neisseria gonorrhoeae

Infections

Similar format of previous guidelines / consultations Convene an expert review panel Identify / refine key questions Review literature

External consultants asked to review the drafted recommendations• selected on the basis of expertise and/or disciplinary or organizational affiliations

CDC considered all suggestions from external consultants and finalized recommendations

Issues

What is the sensitivity and specificity of available tests for CT and GC Is it correct to lump NAATs

Does the sensitivity and specificity of available for CT and GC vary with respect to the anatomic site from which the specimen was collected and/or the specimen type

What class of tests should be recommended for the detection of CT and GC infection; stratify by anatomic site and/or specimen type

What test or combination of tests should be recommended confirmation of CT and GC infection

Issues

Can routine supplemental testing improve the PPV of certain CT and GC tests and at what prevalence level should it be recommended

Positive Predictive Valuelikelihood that the test accurately predicts the true infection status

of the person tested Example

Test 1,000 persons

Test Specificity 99.6 %

True Positive 100 False Positive 4

Prevalence of Infection HIV, syphilis, chlamydia, gonorrhea, etc

10 %

Positive Predictive Value 100/104 = 96 %



0.4 %


Example

Test 1,000 persons

Test Specificity 99.6 %



10 %




0.4 %


Positive Predictive Valuelikelihood that the test accurately predicts the true infection status

of the person tested

Issues

Can routine supplemental testing improve the PPV of certain CT and GC tests and at what prevalence level should it be recommended

Does pooling urine specimens diminish NAAT performance

Should recommendations be made on testing in situations involving medicolegal issues including adult and pediatric CT and GC infections (note: making a recommendation of any test beyond culture would require a preliminary discussion recommendations for off-label testing)

Issues

What test(s) should be recommended for the laboratory diagnosis of LGV and would these vary based on the presentation (i.e. inguinal versus anorectal presentation)

What serologic cut-off values should be used if serology is recommended to aid LGV diagnosis

What (if any) recommendations be made concerning in vitro antibiotic susceptibility testing for GC including but not limited to the actual methodology for the procedure

Chlamydia Immunology and Control Expert Advisory MeetingAtlanta, April 23-25, 2008

Highlight the key questions related to chlamydia natural history, pathogenesis, and immunobiology that have the most important implications for control of chlamydia and its sequelae

Assess extent to which existing data address these key questions, especially with respect to their potential relevance to prevention programs

Identify important remaining gaps in knowledge that would have implications for prevention

Chlamydia trachomatis

Pathology is primarily a function of the host-response Little intrinsic toxicity

Protective immunity has been demonstrated in animal models or animals naturally infected with related chlamydiae Mice, guinea pigs, sheep etc Th1 type DTH in mice

Susceptibility to reinfection is common High rates of reinfection Early Tx of mice resulted in a

disruption of immunity Th2 type DTH in mice

Development of pathology poorly understood How long? Predisposing factors? Reinfection or persistent infection?

Development of immunity that protects against subsequent CT infections has not been conclusively documented in humans Commercial sex workers seem to

be refractory to infection after time

Human data is lacking (absent) on the mechanisms associated with reinfection Bacterial? Host?

Some of what we know Some of what we don’t know

Chlamydia trachomatis

Screening and Tx reduce the natural duration of infection

Despite screening, reinfection rates seem to be increasing

Brunham et al JID 2005

Antibiotic resistance has not been demonstrated among human CT isolates It has been shown in pig isolates

How long does CT persist if left untreated? Brazilian data suggests most half of

the infections are cleared after a year and all are cleared by 5 years

What are the reasons for increases in reinfection rates?

Better Dx tests

Increased / more targeted screening Bacterial changes

Why are some CT infections more difficult to treat? Golden et al NEJM 2005

Some of what we know Some of what we don’t know

Some of What we Learned

Good evidence that repeated episodes of acute diagnosed PID increase the risk of tubal infertility

CT related damage is primarily a function of the host response

Understanding of pathogenesis or timing of occurrence of damage is more limited than most realized additional work needed if new approaches to prevention are to be

developed Existing animal model data offer somewhat less insight than

expected but alternative approaches possible

Data addressing the mechanisms, development, or role of immunity in humans are quite limited But approaches for addressing these gaps provided

Documents

Chlamydia and Gonorrhea Lab Update þBurning Questions þLaboratory Guidelines þCT Immunobiology Consultation The findings and conclusions in this presentation