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

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Presentation on theme: "Tuberculosis Cluster Investigations Using Genotyping Data Frank Romano, MPH CDC Public Health Advisor."— Presentation transcript:

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 –Predicted incidence 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 Assigned to California LabAssigned to Michigan Lab CDC TB Genotyping Program: Genotyping Laboratory Assignments 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 oligonucleotide typing 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

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14 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

15 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

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

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

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

19 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 patients) as of 7/19/2006 Sharing genotype pattern data across jurisdictions (Quarterly Reports from CDC)

20 Ohio’s Role

21 County Genotyping Report

22 County Cluster Report

23 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

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

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

26 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

27 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

28 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

29 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

30 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

31 Cluster OH_ Hamilton County cases + 1 Kentucky case CDC currently assisting with investigation in Indiana

32 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)

33 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

34 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

35 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

36 Prioritizing Cluster Investigations 1.suspected false positive culture 2.cluster of 3+ high-risk persons w/ possible epi-links 3.cluster of 2 high-risk persons w/ possible epi-links 4.cluster of 3+ low-risk persons w/ possible epi-links 5.cluster of 2 low-risk persons w/ possible epi-links 6.cluster of high-risk persons with no epi-links 7.cluster of low-risk persons with no epi-links

37 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

38 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

39 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

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

41 Non-matching Genotypes Patients not epi-linked Interpretation: no evidence of recent transmission

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

43 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

44 Questions????

45 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

46 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

47 ODH Genotyping Contacts Frank Romano, MPH Public Health Advisor (614)

48 Laboratory Contact Person Kevin Sohner, B.S. Ohio Dept. of Health Laboratories Special Microbiology Section 8995 E. Main St., Bldg. 22 Reynoldsburg, OH phone: (614) fax: (614)

49 CDC WebBoard and Contact Information NTCA/CDC TB Genotyping Working Group: Tom Navin, MD at Guide, application instructions and updates for CDC TB Genotyping Program: Guide (printed copy): Alan Schley at


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