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Improving diagnosis. TB laboratory strengthening . Role of laboratory services in TB control. Laboratory services perform crosscutting activities for the three implementation working groups (DEWG, DOTS-Plus, TB/HIV)

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Improving diagnosis

TB laboratory strengthening

role of laboratory services in tb control
Role of laboratory services in TB control

Laboratory services perform crosscutting activities for the three

implementation working groups (DEWG, DOTS-Plus, TB/HIV)

  • Diagnosis of all TB cases (e.g., SM(+), SM (-), extrapulmonary, HIV co-infected, drug resistant)
  • Monitoring patient's response to treatment
  • Participation in TB surveillance; notification/prevalence of TB; DRS
  • Assistance in selecting effective treatment regimens: MDR-TB
  • Human resource development including training
  • Operational research
consequences of poor lab performance
Consequences of poor lab performance
  • Unreliable diagnosis results: over/under diagnosing of TB patients
  • Individual level:
    • Undiagnosed TB cases: (disease transmission, death)
    • Mismanagement of patients (MDR-TB)
    • Over diagnosed patients: (bear the effects of long &

unnecessary treatment, disease stigma)

  • National/Global level:
    • Low case detection,
    • Continuous transmission and
    • Ultimately poorly performing TB control programme
situation analysis 22 hbcs
Situation Analysis (22 HBCs)
  • 18 countries have National Reference Laboratory (NRL) to oversee the organization and performance of the network; however some NRLs are weak and not fully functional
  • 18 HBCs claim to have EQA scheme for smear microscopy; however, majority report it's limited coverage and suboptimal quality
  • 14 countries perform culture at the national/regional level according to nationally-defined specifications, which are not always consistent with international recommendations. In addition, the quality of culture is unknown
  • Major impediments to perform diagnostic tests (especially culture and DST):
      • inadequate equipment and infrastructure
      • limited technical knowledge
      • Insufficient human and financial resources
stop tb strategy and laboratory
Stop TB Strategy and laboratory
  • Pursuing quality DOTS expansion and enhancement
    • Political commitment
    • Case detection through quality-assured bacteriology
    • Standardised treatment, with supervision and patient support
    • Effective drug supply system
    • Monitoring system and impact evaluation
  • Addressing TB/HIV and MDR-TB
  • Contributing to health system strengthening
  • Engaging all care providers
  • Empowering patients and communities
  • Enabling and promoting research
improving diagnosis planning framework
Improving diagnosis- planning framework


  • Organization of TB laboratory network (prevalence and population distribution)
  • Provide laboratory equipment supplies and reagents
  • Implement quality assurance programme for smear microscopy, culture and DST
  • Promote human resource development
  • Meetings and Workshops
  • Support technical assistance
  • Promote operational research
  • Expedite the diagnosis of smear negative & extrapulmonary TB in high HIV prevalence areas
peripheral level level 1
Peripheral level (Level 1)
  • Located at primary health centers or district hospitals
  • Activities:
    • Sputum collection
    • Smear microscopy
    • Recording and reporting
    • Slide collection for EQA
  • Manpower: ≤ 1(2) worker(s); >2-3 / <20 smears per day
  • Population coverage: 100-200K
intermediate level level 2
Intermediate level (Level-2)
  • Located at regional health institutions including hospitals
  • Activities:
    • Services to clinics: FM/ZN smear microscopy
    • Culture / ID of MTB; referral services
    • Support activities: (supply of reagents/materials, training; EQA for smear microscopy including supervision)
  • Manpower: 2-3 workers (only for TB work)
  • Population Coverage: 500 - 1,500K
central level level 3
Central level (Level 3)
  • Part of the central public health laboratory, research laboratory, or upgraded laboratory in the country’s principal tuberculosis institution
  • Activities:
    • National reference laboratory for the TB program,
    • Development of standardized manuals and guidelines
    • Training
    • External Quality Assurance
    • Perform: smear microscopy, culture and DST
generally 3 levels in a tb lab network
Generally 3 levels in a TB lab network




  • All functions of level 1 and 2
  • Identification of mycobacteria
  • other than MTB
  • DST of M. Tuberculosis
  • laboratory equipment services
  • and maintenance
  • Laboratory manuals and
  • guidelines for all lab services
  • Primary link with NTP
  • Supervision of intermediate QA
  • of culture and microscopy
  • Training of intermediate
  • organization of DRS
  • Operational and applied research
  • All functions of level 1
  • fluorescence microscopy (optional)
  • Digestion and decontamination
  • of specimens
  • Culture and identification of MTB
  • Training of staff
  • Support and supervision of
  • peripheral staff for microscopy
  • Preparation and distribution
  • of reagents
  • QA and panel testing of
  • microscopy
  • Manpower: 2-3 only for TB
  • Coverage: 500K-1.500K
  • Receipt of specimens
  • Preparation and staining
  • of smears
  • ZN microscopy /recording
  • Reporting of results
  • Maintenance of lab register
  • Management of reagents
  • and supplies
  • Internal QC
  • Participation in EQA system

Manpower: 1-2 staff

Coverage: 100-200K

Internal and External Quality Assurance at all levels

external quality assessment
External Quality Assessment
  • Early warning-system for problems
  • Measure of laboratory quality
  • Valuable benchmarking tool (standardization and traceability)
  • Indicator of where to direct improvement efforts
  • Monitor of changes in technology and testing practices (evaluation component)
quality assurance programme components
Quality Assurance Programme Components
  • Supervision
  • Rechecking/panel testing
  • Internal quality control
Strengthen the national capacity to perform

culture for diagnostic purposes

epidemiological and programmatic conditions have changed
Epidemiological and programmatic conditions have changed
  • The number of repeatedly sputum negative TB cases is increasing,

mainly due to the HIV epidemic

  • Many countries are implementing DRS and monitoring MDR trends
  • Second line drugs are available and a growing number of countries

implement DOTS-Plus strategy

  • Culture is increasingly used even in resource limited countries
estimated cost of culture lj method dst proportion method per laboratory
Estimated cost of culture (LJ method) & DST (proportion method) per laboratory
  • Capital investment per laboratory: 200,000$US
  • Consumables, media and pure substances for 1000 cultures and DST: 22,000$US
  • Training: national & international: 20,000$US
  • EQA for culture and DST: 5,000$US/ year
  • Staff salaries
proposed approach to strengthen capacity to perform culture
Proposed approach to strengthen capacity to perform culture
  • Develop/strengthen the capacity to perform culture at theintermediate level as an essential component of DOTS expansion
  • Initially, 1 culture facility should be established per ~ 3 to 5 million population
  • Introducing culture in step wise approach to cover all eligible population by 2015 (number of facilities will depend on the national policy)
smear microscopy optimizations
Smear microscopy optimizations

Outcomes of expert consultation meeting (1-2 September 2005)

The meeting was organized to discuss the outcomes of the systematic

literature review to determine the strength of existing data, identify

knowledge gaps, and define a research agenda regarding the following


  • Fluorescence microscopy (45 studies)
  • Sputum processing methods (83 studies)
  • Number of sputum smears per TB suspect (41 studies)
fluorescent microscopy fm
Fluorescent microscopy (FM)


  • Improve the sensitivity of sputum microscopy by 10%
  • Shorten time of diagnosis
  • Reduce laboratory workload; FM recommended to be used in high volume settings >100 smears


  • Countries wishing to implement FM at the peripheral level, in lower volume settings, should do so within the context of operational research
  • FM may be considered at all levels in high HIV prevalence countries

Collaboration with TDR, FIND on operation research to further

evaluate applicability, sustainability of this technology

fluorescent microscopy
Fluorescent microscopy

Close collaboration with FIND and WHO on evaluation

of the LED portable fluorescent microscope

sputum processing methods
Sputum processing methods


  • Use of different chemicals and methodology
  • Moderate sensitivity improvement
  • Serious concerns regarding the use of centrifuge and bio-safety issues


  • Concentration methods not recommended
  • Sedimentation may be promising and less problematic to implement; however, multi-centre studies are required to investigate the performance and feasibility with standardised method

Collaboration with TDR and FIND on design and implementation of

operational research to evaluate sedimentation methods.

number of sputum smears per tb suspect
Number of sputum smears per TB suspect


  • The results indicated limited incremental yield of the 3rd sputum examination (2-5%)
  • However, there was some bias in studies design and difference in case definition

Points to be considered:

  • Dilemma on improving sensitivity (more false positive) or specificity
  • Workload issues (more time allocation for examination of slide => improved output)


The questions should be studied in the context of case definition (this topic will be

presented and discussed during the upcoming STAG meeting)