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Module 1Understanding Tuberculosis, the Global Emergency


Learning ObjectivesAt the end of this module, the participant will be able to:

1. Explain the TB epidemic and the annual global TB burden 2. Describe the forms of TB and how TB is transmitted 3. Discuss the ISTC Standards for Diagnosis 4. Define and compare various methods of TB diagnosis,


Learning Objectives5. Describe NTP and its purposes 6. Describe the role of the laboratory in NTP 7. Describe the DOTS component of STOP TB strategy 8. Explain the importance of AFB microscopy in the DOTS program 9. Describe levels of TB laboratory services.


What is tuberculosis? The TB epidemic and the annual global TB burden Transmission and forms of TB Risk of Disease ISTC Standards for Diagnosis TB Diagnosis

Content Overview


Content Overview National TB Program and its purposes The role of the laboratory in NTP The DOTS component of STOP TB strategy The importance of AFB-microscopy in DOTS programs Levels of laboratory services


Global EmergencyTuberculosis kills 5,000 people a day !

2.3 million die each year !

Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx


Disturbing Statistics 1/3 of worlds population is infected with TB 8 Million people develop active TB every year TB kills more young women than any otherdisease

More than 100,000 children will die from TBthis year

Hundreds of thousands of children will becomeTB orphansSource: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx



9th amongst the 22 high-burdened countriesworldwide (WHO watchlist)

4th amongst the countries in the Western PacificRegion of WHO (2nd among the HBCs in WPRO)

8th amongst the countries with high burden forMDRTB TB is 6th in mortality and morbidityTB morbidity & mortality Natl Objectives for Health 2005-2010 DOH


What is TB?TB is an infectious disease that affects mainly the lungs (pulmonary TB or PTB) but can also attack any part of the body (extra-pulmonary TB or EPTB)

A person with PTB is infectious to others!Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx


The Causes of TBMycobacterium tuberculosis complex

Mycobacterium tuberculosis Mycobacterium bovisSource: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx


Staining CharacteristicsMycobacteria are called Acid-Fast Bacilli (AFB) due to their microscopic appearance after decolorization. Organisms appear red on a blue background

Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx


TB Transmission (infection)Person to person via Airborne transmission in Confined environment12

Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx

Risk Factors for Infection Exposure to TB bacilli Duration of exposure to a person with PTB Intensity of exposure

Untreated AFB smear positive PTB cases are the most infectious

Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx


Risk Factors for Disease Development of disease depends onindividual susceptibility

HIV increases the risk of getting TB disease10% Life time risk of TB in HIV negative10% Annual risk of TB in HIV positive

14Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx

What is MDR-TB? Multidrug-resistant TB (MDR TB) is TB that isresistant to at least two of the best anti-TB drugs, isoniazid and rifampicin. These drugs are considered first-line drugs and are used to treat all persons with TB disease.

ISTC TB Training Modules 2009


What is XDR-TB? Extensivelydrug resistant TB (XDR TB) is a relatively rare type of MDR TB. XDR TB is defined as TB which is resistant to isoniazid and rifampin, plus resistant to any fluoroquinolone and at least one of three injectable second-line drugs (i.e., amikacin, kanamycin, or capreomycin).

ISTC TB Training Modules 2009


Purpose ISTC Purpose of ISTC


ISTC TB Training Modules 2009


THE ISTC Intended to facilitate the effective engagement of all care providers in delivering high quality care for patients of all ages. intended to complement, not replace, national and local recommendations. The ISTC should be viewed as a living document that will be revised as technology, resources, and circumstances change.19



ISTC TB Training Modules 2009

Standards for Diagnosis


ISTC TB Training Modules 2009

Standards for Diagnosis

22ISTC TB Training Modules 2009

Microbiologic Diagnosis of TBSignificance of microbiologic testing for public health goals and patient care: WHO global target of 70% case detection of new smearpositive cases Rapid and accurate case detection coupled with effective treatment is essential to reduce the incidence of TB Failure to perform a proper diagnostic evaluation before initiating treatment potentially: Exposes the patient to the risks of unnecessary or wrong treatment May delay accurate diagnosis and proper treatment23ISTC TB Training Modules 2009

ISTC Standard 1All persons with otherwise unexplained productive cough lasting two-three weeks or more should be evaluated for tuberculosis24

ISTC Standard 2All patients (adults, adolescents, and children who are capable of producing sputum) suspected of having pulmonary TB should have at least two sputum specimens obtained for microscopic examination in a quality-assured laboratory. When possible, at least one early morning specimen should be obtained.25

ISTC Standard 3For all patients (adults, adolescents, and children) suspected of having extrapulmonary TB, appropriate specimens from the suspected sites of involvement should be obtained for microscopy, culture, and histopathological examination.


NTPExtra-Pulmonary TB (EP) A patient with at least one mycobacterial smear/culture positive from an extra-pulmonary site (organs other than the lungs: pleura, lymph nodes, genito-urinary tract, skin, joints and bones, meninges, intestines, peritoneum, and pericardium, among others) A patient with histological and/or clinical evidence consistent with active extra pulmonary TB and there is a decision by a physician to treat the patient with anti-TB drugs All EP cases shall undergo DSSM prior to treatment.NTP MOP 200527

ISTC Standard 4All persons with chest radiographic findings suggestive of tuberculosis should have sputum specimens submitted for microbiological examination.28

ISTC Standard 5The diagnosis of sputum smear-negative pulmonary tuberculosis should be based on the following criteria: At least two negative sputum smears (including at least one early morning specimen) Chest radiography findings consistent with tuberculosis Lack of response to a trial of broad-spectrum antimicrobial agents (Note: Because the fluoroquinolones are active against M. tuberculosis complex, and thus may cause transient improvement in persons with tuberculosis, they should be avoided.)


ISTC Standard 5For such patients, sputum cultures should be obtained. In persons who are seriously ill or have known or suspected HIV infection, the diagnostic evaluation should be expedited and if clinical evidence strongly suggests TB, a course of antituberculosis treatment should be initiated.ISTC TB Training Modules 200930

ISTC Standard 6In all children suspected of having intrathoracic (i.e., pulmonary, pleural, and mediastinal or hilar lymph node) TB, bacteriological confirmation should be sought through examination of sputum (by expectoration, gastric washings, or induced sputum) for smear microscopy and culture. In the event of negative bacteriological results, a diagnosis of TB should be based on: The presence of abnormalities consistent with TB on chest radiography A history of exposure to an infectious case, evidence of TB infection (positive tuberculin skin test or interferon gammarelease assay), and Clinical findings suggestive of TB31

ISTC Standard 6For children suspected of having EPTB, appropriate specimens from the suspected sites of involvement should be obtained for microscopy and for culture and histopathological examination.32

Diagnosis of TB Direct demonstration of AFB in sample Growth of TB bacilli in culture Skin Test Nucleic Acid Amplification tests (NAATs) T-cell-based interferon-gamma release assay (IGRAs) X-Ray33

ISTC TB Training Modules 2009

Sputum Smear MicroscopySputum smear microscopy is the most important test for the diagnosis of pulmonary TB in many areas of the world Direct smears (unconcentrated specimen) are most common Fluorescence microscopy and chemical processing can increase sensitivity Assessment of laboratory quality is essential34

ISTC TB Training Modules 2009

Sputum Microscopy: Direct SmearsDirect smears of unconcentrated sputum: Fast, simple, inexpensive, widely applicable Extremely specific for M. tuberculosis in high-incidence areas Ziehl-Neelsen staining (carbol fuchsin type) most commonISTC TB Training Modules 200935

Sputum Smear MicroscopyCarbolfuchsin-based stains Utilize a regular light microscope Must be read at a higher magnification Two types: Ziehl-Neelsen and Kinyoun. Both use

carbolfuchsin/phenol as the primary dye Smear is then decolorized with acid (HCI) alcohol and counter-stained with methylene blue

ISTC TB Training Modules 2009


Ziehl-Neelsen (ZN) Stain

ISTC TB Training Modules 2009


Sputum Microscopy: Fluorochrome StainFluorochrome stain

Fluorochrome stained smears re