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Tuberculosis Cluster Investigations Using Genotyping Data

Tuberculosis Cluster Investigations Using Genotyping Data. Frank Romano, MPH CDC Public Health Advisor. Historical Perspective. 1989 ACET & CDC Publishes A Strategic Plan for the Elimination of TB in the US Predicted incidence rate of 3.5 per 100,000 by 2000

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Tuberculosis Cluster Investigations Using Genotyping Data

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  1. Tuberculosis Cluster Investigations Using Genotyping Data Frank Romano, MPH CDC Public Health Advisor

  2. Historical Perspective • 1989 ACET & CDC Publishes A Strategic Plan for the Elimination of TB in the US • Predictedincidence rate of 3.5 per 100,000 by 2000 • Predicted the elimination of TB by 2010

  3. History (cont.) • Late 1980’s – early 1990’s: Few states performing TB genotyping using IS6110 RFLP • Jan. 1990–August 1993: Strain W • MDR Strain • 357 cases reported in NYC prisons and hospitals • HIV seropositive population • 80% mortality (Duration 4–6 weeks)

  4. April 1996: CDC establishes the National Tuberculosis Genotyping and Surveillance Network (NTGSN) • 1996—2000: NTGSN conducts population-based study to determine the frequency of specific strains geographically using IS6110 RFLP and Spoligotyping • 2001: Results of study published

  5. Use Genotype Results to Better Understand: • spread of related strains in communities • geographic mobility of related strains • relatedness of strains in persons at high risk for tuberculosis • capacity of local TB controllers to identify patients involved in outbreaks and to provide a database of DNA fingerprints for tuberculosis control activities

  6. CDC TB Genotyping Program • January 2004, the CDC Tuberculosis Genotyping Program was initiated to enable rapid genotyping of isolates from every patient in the USA with culture-positive tuberculosis (TB) • The Federal Tuberculosis Task Force recommended nationwide TB genotyping in response to the Institute of Medicine report, Ending Neglect • The TB Genotyping Program contracts with laboratories that provide results within 10 working days using two PCR-based genotyping tests

  7. PCR Based Testing • Polymerase chain reaction (PCR) • Only a small amount of culture is needed for PCR-based genotyping, and the PCR test can be completed in 1day* *because the PCR tests are batched, the actual turn-around time from receipt of a specimen to reporting the results can be longer

  8. CDC TB Genotyping Program Goal: Provide nationwide rapid genotyping tests • Two CDC-funded laboratories perform genotyping for one isolate from every culture-positive TB case in the US • CDC funded TB programs submit isolates to regional genotyping labs • Genotyping labs report results within 10 days

  9. CDC TB Genotyping Program: Genotyping Laboratory Assignments LAB LAB Assigned to California Lab Assigned to Michigan Lab

  10. CDC Genotyping Program Laboratory Methods Two tiered testing to maximize discriminatory power PCR • MIRU Variable number tandem repeats of mycobacterial interspersed repetitive units • Spoligotyping Spacer oligonucleotidetyping IS6110-based RFLP • Done only for isolates that match by both PCR tests • At request of CDC grantee

  11. Comparison of Testing Methods • IS6110RFLP-(Restriction Fragment Length Polymorphism) • Considered most discriminatory test worldwide • Disadvantages—Cost, time, need for specialized training & lab equipment • Spoligotype- (Spacer Oligonucleotide Typing) • Lower Specificity than RFLP • Lower cost, rapid results • MIRU- (Variable number tandem repeats of mycobacterial interspersed repetitive units) – Lower Specificity than RFLP – Lower cost, rapid results

  12. Tuberculosis Genotyping Guide National TB Controllers Association Centers for Disease Control and Prevention

  13. Value of Genotyping Identify and prevent transmission • Enhance contact investigations • Identify nontraditional settings of transmission • Facilitate identification of clusters and outbreaks Improve clinical management • More readily identify false-positive cultures • Help distinguish between relapse and reinfection

  14. Value of Genotyping (II) Enhance surveillance • Evaluate prevalence of M. tuberculosis genotypes • Monitor trends in recent transmission Evaluate prevention activities • Completeness of contact investigations • Progress toward TB elimination

  15. CDC TB Genotyping Program • All programs with CDC Cooperative Agreements are eligible (64) • Program options • Selective genotyping • Universal genotyping • Universal genotyping for subregion

  16. TB Genotyping Programs NYC D.C. SD Universal Selective Mixed Not enrolled Aug 04

  17. TB Genotyping Programs NYC D.C. SD Universal Selective Mixed Not enrolled June 06

  18. CDC National TB Genotyping Program Update • As of May 1, 2006, 15,573 isolates have been submitted nationally • 439 isolates submitted from Ohio as of 7/19/2006 • Ohio has 44 clusters (range 2 - 13 patients) as of 7/19/2006 • Sharing genotype pattern data across jurisdictions (Quarterly Reports from CDC)

  19. Ohio’s Role

  20. County Genotyping Report

  21. County Cluster Report

  22. Genotyping Results • Interpreting genotyping results and epidemiologic data • When to initiate a cluster investigation, initiate (expand) an outbreak investigation, or do nothing Epi-link: a characteristic that 2 or more TB patients share that explains where and when TB could have been transmitted between them

  23. Interpreting Results • Matching genotype vs. non-matching genotype • Epi-linked vs. non-epi-linked • Involved in same recent chain of transmission vs. not involved

  24. Matching Genotypes False-positive culture? Suspected false-positives are a priority • need to stop treatment for falsely diagnosed patients as soon as possible

  25. False-Positive Cultures Clinical Picture • Health care provider or clinical lab is suspicious • patient had only 1 positive culture out of 1 or multiple specimens collected • patient asymptomatic for TB • patient’s chest radiograph not consistent with TB • patient has another confirmed diagnosis to explain symptoms

  26. False-Positive Cultures Laboratory • specimens were processed in the same laboratory on the same day • isolates were collected in the same hospital or clinic within 3 days • PCR genotyping pattern matches the laboratory control strains (H37rv or H37ra) or laboratory proficiency specimens

  27. False-Positive Cultures False-positive result confirmed: • identify which patients actually have TB and which patients were misdiagnosed • alert the health care providers so they can correctly diagnose and treat the misdiagnosed patients • alert the laboratory so the cause of the false-positive culture can be determined and corrected

  28. Matching Genotypes Patients Epi-linked prior to genotyping Interpretation: • probably involved in same chain of recent transmission • RFLP confirmation or cluster investigation not needed • may determine that an outbreak investigation is needed

  29. Outbreak Investigations • An increase in the expected number of cases • Transmission continues despite adequate control efforts by the TB program • The contact investigation has grown to a size that requires additional outside help

  30. Cluster OH_009 • 11 Hamilton County cases + 1 Kentucky case • CDC currently assisting with investigation in Indiana

  31. 3 1 4 2 1 12 34 1 3 2 3 Number of isolates as of 06/30/2006 n = 55 IN = 61.8% of isolates (Note: 1 case in Florida matches on spoligotype and is missing MIRU but is linked epidemiologically)

  32. Matching Genotypes Patients have possible epi-links • are there 3+ people in the cluster? • are there high-risk people in the cluster? If yes, request RFLP for confirmation • if RFLP does not confirm match, no further investigation needed • if RFLP confirms match, consider doing a cluster investigation

  33. High-risk Patients • live in congregate settings • are infected with HIV or have other immunocompromising conditions • are children • have cavitation on chest radiographs • have MDR TB • are homeless

  34. Cluster Investigations Should only be done when needed • can be labor intensive • detailed cluster investigation protocols and data collection forms are available from CDC • review information previously collected to determine if additional information is needed • may need to interview patients again

  35. Prioritizing Cluster Investigations • suspected false positive culture • cluster of 3+ high-risk persons w/ possible epi-links • cluster of 2 high-risk persons w/ possible epi-links • cluster of 3+ low-risk persons w/ possible epi-links • cluster of 2 low-risk persons w/ possible epi-links • cluster of high-risk persons with no epi-links • cluster of low-risk persons with no epi-links

  36. Matching Genotypes Patients have no epi-links identified, but are involved in same chain of recent transmission Interpretation: Failure to identify known epi-links due to - • inadequate contact investigation • transmission from casual contact

  37. Matching Genotypes Patients not epi-linked and not involved in same chain of recent transmission Interpretation: Matching genotypes with no recent transmission due to - • transmission of endemic strain • large outbreak in the past • false positive culture(s) • laboratory error

  38. Non-matching Genotypes Patients epi-linked and involved in same chain of recent transmission Interpretation: non-matching genotypes with no recent transmission due to - • genotypes that changed slightly over time • co-infection with >1 strain of M. tb • laboratory error

  39. Non-matching Genotypes Patients epi-linked and not involved in same chain of recent transmission Interpretation: • misleading epi-links identified

  40. Non-matching Genotypes Patients not epi-linked Interpretation: • no evidence of recent transmission

  41. Large Clusters As clusters grow in size, it becomes easier to: • identify epi-links • identify an endemic strain

  42. Deciding What To Do Making the correct decision depends upon having complete and accurate data from a variety of sources • patient interviews • contact investigations • laboratory results • medical records

  43. Questions????

  44. Definitions Selective Genotyping: The process of submitting only selected high priority M tuberculosis isolates for genotyping Universal Genotyping: The process of submitting all M tuberculosis isolates for genotyping

  45. Definitions Genotype: The designation that results from one or more of the three genotyping techniques used for M tuberculosis: Spoligotyping, MIRU analysis, and IS6110-based RFLP Genotyping: Also referred to as DNA fingerprinting. A laboratory approach that provides a description of the genetic makeup and relatedness of M. tuberculosis isolates Cluster: A genotyping cluster is two or more M tuberculosis isolates that share matching genotypes An epidemiologic cluster is two or more persons with TB who share epidemiologic links

  46. ODH Genotyping Contacts • Frank Romano, MPH Public Health Advisor (614) 466-6563 Frank.Romano@odh.ohio.gov

  47. Laboratory Contact Person Kevin Sohner, B.S. Ohio Dept. of Health Laboratories Special Microbiology Section 8995 E. Main St., Bldg. 22 Reynoldsburg, OH 43068 phone: (614) 644-4668 fax: (614) 644-4412 e-mail: ksohner@odh.ohio.gov

  48. CDC WebBoard and Contact Information • NTCA/CDC TB Genotyping Working Group: Tom Navin, MD at TNavin@cdc.gov • Guide, application instructions and updates for CDC TB Genotyping Program: http://web-tb.forum.cdc.gov Guide (printed copy): Alan Schley at ASchley@cdc.gov

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