tb dots module1
TRANSCRIPT
1 1
Module 1 Understanding Tuberculosis,
the Global Emergency
2 2
Learning Objectives At 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,
3
Learning Objectives
5. 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.
4 4
Content Overview • 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
5
• 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
Content Overview
6 6
Global Emergency
Tuberculosis kills 5,000 people a
day !
2.3 million die each year !
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
7 7
• 1/3 of world’s population is infected with TB
• 8 Million people develop active TB every year
• TB kills more young women than any other
disease
• More than 100,000 children will die from TB
this year
• Hundreds of thousands of children will become
TB orphans
Disturbing Statistics
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
8
PHILIPPINE STATUS
9th amongst the 22 high-burdened countries worldwide (WHO watchlist)
4th amongst the countries in the Western Pacific Region of WHO
(2nd among the HBC’s in WPRO)
8th amongst the countries with high burden for MDRTB
TB is 6th in mortality and morbidity
TB morbidity & mortality Nat’l Objectives for Health 2005-2010 DOH
9 9
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
10 10
Mycobacterium tuberculosis complex
• Mycobacterium tuberculosis
• Mycobacterium bovis
The Causes of TB
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
11 11
Staining Characteristics
• Mycobacteria 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
12 12
TB Transmission
(infection)
Person to person
via
Airborne transmission
in
Confined environment
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
13 13
• 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
Risk Factors for Infection
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
14 14
Risk Factors for Disease
• Development of disease depends on individual susceptibility
• HIV increases the risk of getting TB disease
10% Life time risk of TB in HIV negative
10% Annual risk of TB in HIV positive
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
15
What is MDR-TB?
• Multidrug-resistant TB (MDR TB) is TB that is
resistant 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
16
What is XDR-TB?
• Extensively drug 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
17
Purpose of ISTC Purpose of ISTC
ISTC TB Training Modules 2009
18
19
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.
20
Introduction
ISTC TB Training Modules 2009
21
Standards for Diagnosis
ISTC TB Training Modules 2009
ISTC TB Training Modules 2009
22
Standards for Diagnosis
ISTC TB Training Modules 2009
23
Microbiologic Diagnosis of TB
Significance of microbiologic testing for public health goals and patient care:
WHO global target of 70% case detection of new smear-positive 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 treatment
24
ISTC Standard 1
All persons with
otherwise
unexplained
productive cough
lasting two-three
weeks or more
should be
evaluated for
tuberculosis
25
ISTC Standard 2 All 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.
26
ISTC Standard 3
For 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.
27
NTP Extra-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 2005
28
ISTC Standard 4
All persons with chest
radiographic findings
suggestive of
tuberculosis should
have sputum
specimens submitted
for microbiological
examination.
29
ISTC Standard 5 The 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.)
30
ISTC Standard 5
For 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 2009
31
ISTC Standard 6
In 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 gamma-release assay), and
Clinical findings suggestive of TB
32
ISTC Standard 6
For children suspected of
having EPTB, appropriate
specimens from the
suspected sites of
involvement should be
obtained for microscopy
and for culture and
histopathological
examination.
33 33
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-Ray
ISTC TB Training Modules 2009
34
Sputum Smear Microscopy • Sputum 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
essential
ISTC TB Training Modules 2009
35
Sputum Microscopy: Direct Smears
Direct 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
common
ISTC TB Training Modules 2009
36
Sputum Smear Microscopy
Carbolfuchsin-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
37
Ziehl-Neelsen (ZN) Stain
ISTC TB Training Modules 2009
38
Sputum Microscopy: Fluorochrome Stain
Fluorochrome stain
• Fluorochrome stained smears require a fluorescent
microscope
• Generally read at 250X-450X magnification which
allows rapid scanning of the smear
• Auramine-rhodamine is an example of such a stain
where the AFB appear yellow against a black
background
ISTC TB Training Modules 2009
39
Auramine-rhodamine Stain
ISTC TB Training Modules 2009
40 40
Advantages of
AFB Smear Microscopy
• Microscopy is a simple convenient test
• Requires minimal infrastructure and equipment
• Highly accurate, inexpensive and fast
• Accessible to the majority of patients
• Prioritizes infectious cases
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
41 41
Limitations of Microscopy
• Can not distinguish between dead or live bacteria
• High bacterial load >3000–5000 AFB /mL is required for detection
• Can not do species identification
• Can not perform Drug Susceptibility Testing
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
42
Fluorescence Microscopy
Advantages:
• More accurate: 10% more sensitive
than light microscopy, with specificity
comparable to ZN staining
• Faster to examine = less technician
time
Disadvantages:
• Higher cost and technical complexity,
less feasible in many areas
Steingart KR, et al. Lancet Infect. Dis. 2006; 6 (9):570-81
43
Although sputum
microscopy is the first
bacteriologic diagnostic
test of choice, both culture
and drug susceptibility
testing (DST) can offer
significant advantages in
the diagnosis and
management of TB.
Culture and Drug Susceptibility Testing
ISTC TB Training Modules 2009
44
Culture: Advantages
• Higher sensitivity than smear microscopy (culture
can make diagnosis despite fewer bacilli in
specimen)
• If TB suspected and sputum smears are negative,
culture may provide diagnosis
• Allows for identification of mycobacterial species
• Allows for drug susceptibility testing
ISTC TB Training Modules 2009
45
Culture: Disadvantages
• Cost
• Technical complexity
• May take weeks to get results
• Requires ongoing quality assurance
Therefore, more likely to be found in major
referral centers. Avoid delaying appropriate TB
treatment in suspicious cases while awaiting
results.
ISTC TB Training Modules 2009
46
Culture: Solid Media
• Solid media have the
advantage that organisms
(colonies) can be seen on the
surface of the medium
• Types most commonly used
are:
• Lowenstein-Jensen:
egg-based
• Middlebrook 7H 10 or 7H11:
agar-based
• Ogawa
ISTC TB Training Modules 2009
47
MGIT Incubator
Culture: Liquid Media
• More sophisticated equipment
• Faster detection of growth
• Higher sensitivity than solid media
• Can also be used for drug-
susceptibility testing
• Two examples:
• BACTEC
• MGIT
MGIT
BACTEC
ISTC TB Training Modules 2009
48
Culture: Identification of Mycobacteria
Growth characteristics (preliminary ID)
• Preliminary indication of M.tb can be determined from colony
characteristics
• Rate of growth
• Colonial morphology
• Pigmentation
Biochemical tests
• There is a battery of 8 – 12 biochemical tests used to
differentiate M.tb within the genus
• Nitrate reduction and niacin production are definitive for M.tb
ISTC TB Training Modules 2009
49
Smooth, buff-colored
colonies suggestive of
Mycobacterium avium
complex Rough, buff-colored colonies
suggestive of Mycobacterium
tuberculosis
Culture: Identification of Mycobacteria
Visual assessment of colony morphology:
ISTC TB Training Modules 2009
50
Culture: Cross-Contamination
• Be aware that faulty
technique can lead to
laboratory cross-
contamination of
specimens (difficult to
verify without access to
more technical testing).
• Adequate quality control is
an essential component of
any mycobacteriology
laboratory.
ISTC TB Training Modules 2009
51
Rapid Diagnostic Testing
Nucleic acid probe tests (non-amplified) to
identify organisms grown in culture:
• DNA probe tests are species or complex specific
• Commercial probes are available for M.tb complex, MAC, M.
kansasii and M. gordonae
Nucleic acid amplification tests (NAAT):
• These tests are designed to amplify and detect DNA
specific to M.tb
• Enables direct detection of M.tb in clinical specimens
ISTC TB Training Modules 2009
52
Other Rapid Diagnostic Tests
• Loop-mediated isothermal amplification (LAMP)
• Rapid, simplified NAAT still under investigation
• May be more feasible in lower resource settings
• Immunological tests
• Serologic tests for antibody, antigens, and
immune complexes; not currently accurate
enough to replace microscopy and culture.
ISTC TB Training Modules 2009
53
Other Rapid Diagnostic Tests
• High performance liquid chromatography (HPLC)
• HPLC uses a liquid chromatography method to identify mycobacteria based on their mycolic acid profiles (cell wall composition)
• The equipment is expensive and is usually reserved for larger, specialized, reference laboratories
ISTC TB Training Modules 2009
54
Rapid Drug Susceptibility Tests
• Line-probe assays
• Identifies M.tb and genetic
mutations associated with
INH and RIF resistance
• Can be used directly on
sputum specimens, results
within 1-2 days Molecular beacons
Bacteriophage-based assays
*GenoType MTDBRplus strips
(Hain Lifescience)
*Barnard et al. Am. J. Respir. Crit. Care Med 2008; 177: 787-792
55 55
National Tuberculosis Control
Program (NTP)
• Objectives
• Reduce mortality, morbidity and disease transmission and avoid the development of drug resistance
• In the long term, to eliminate suffering due to TB
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
56 56
Goals of the NTP
• Detect at least 70% of the infectious cases
• Cure at least 85% of newly detected cases of smear-positive TB
• Reduce prevalence of and deaths due to TB
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
57
NTP • Case finding, which is the identification and
diagnosis of TB cases among individuals with
suspected signs and symptoms of TB, is a basic
step in TB control.
• Fundamental to case finding is the detection of
infectious cases through direct sputum smear
microscopy (DSSM).
• DSSM results serve as basis for categorizing TB
symptomatics according to standard case definition,
monitor progress of patients with sputum smear-positive
TB while they are receiving anti–TB treatment
• These are also used to confirm cure at the end of
treatment.
NTP MOP 2005
58
NTP
National TB Reference Laboratory
• Quality assurance of sputum microscopy smear
are done quarterly
• Objectives of QA program: • ensure that the reported results are accurate
• identify practices that are potential sources of error
• ensure that appropriate corrective actions are initiated
NTP MOP 2005
59 59
What is STOP TB Strategy
1. Pursuing quality DOTS expansion and enhancement
2. Addressing TB/HIV and MDR-TB
3. Contributing to health system strengthening
4. Engaging all care providers
5. Empowering patients and communities
6. Enabling and promoting research
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
60
TB Pathogenesis Exposure
Infection
Active Disease
Inactive Disease
Who has Tuberculosis?
STOP TB AT THE SOURCE!
61 61
DOTS Component of STOP TB
Strategy
• Political commitment to TB control
• Case detection by quality assured bacteriology
• Regular, uninterrupted supply of high quality anti-TB drugs
• Standardized treatment with supervision and patient support
• Standardized recording and reporting
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
62 62
Benefits of DOTS
• Produces cure rates of up to 95 %
• Prevents new infections
• Prevents the development of MDR-TB
• Cost effective
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
63
IMPORTANCE OF ACID-FAST BACILLI (AFB)
MICROSCOPY IN DOTS PROGRAMS
• Diagnosis
• Treatment Follow-up
64 64
Role of Laboratory
• Detection of infectious cases
• Monitoring of treatment progress
• Documentation of cure
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
65 65
Detection and treatment
of infectious cases
reduces the spread of
Tuberculosis!
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
66 66
• AFB smear-positive patients are usually sick and seek treatment.
• AFB smear-positive patients are much more likely to die if untreated.
• Untreated, an AFB smear-positive patient may infect 10–15 persons/year.
Pulmonary Positive Patients
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
67
NTP RESPONSE TO MDR-TB PROBLEM
• Policy and technical support:
AO 2008-0018: “Guidelines for the Implementation of
PMDT”
• Implementing guidelines and training modules for
PMDT
• Mainstreaming of MDR-TB services to the NTP
• Public-private collaboration from diagnosis to
management of cases
NTP MOP 2005
68
ISTC Standard 12
• Patients with or highly likely to have tuberculosis caused by drug-resistant (especially MDR/XDR) organisms should be treated with specialized regimens containing 2nd-line antituberculosis drugs
• The regimen chosen may be standardized or based on suspected or confirmed drug susceptibility patterns
• At least four drugs to which the organisms are known or presumed to be susceptible, including an injectable agent, should be used, and treatment should be given for at least 18–24 months beyond culture conversion
69 69
Intermediate
laboratories
Peripheral Laboratories
Laboratory Network
Central
Laboratory
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
70 70
• Located within a general dispensary, clinic or hospital
• Limited services for TB diagnosis
• Sputum specimen collection
• AFB sputum smear microscopy
Peripheral Laboratory
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
71 71
• Regional/provincial or large hospital
• Services for TB diagnosis
• Sputum specimen collection
• Sputum smear microscopy
• Culture and identification of MTB
• Support for peripheral laboratories
• Supply of reagents and materials
• Training, supervision, EQA of sputum smear microscopy
Intermediate Laboratory
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
72 72
• Country/regional level
• Services for TB diagnosis
• Sputum smear microscopy
• Culture and identification of MTB
• Drug susceptibility testing of TB
• Support for the laboratory network
• Advice on procurement
• Organization and participation in training, supervision, EQA of sputum smear microscopy
• Other activities
• Participation in operational research
• Drug resistance surveillance
Central Laboratory
Source: http://wwwn.cdc.gov/dls/ila/acidfasttraining/section4.aspx
73 73
Laboratory is the key
Component in TB Control
NO LABS
NO DIAGNOSIS
NO TREATMENT
NO DOTS
NO TB CONTROL
74 74
• What is TB and how it is transmitted?
• What are the ISTP Standards for Diagnosis?
• What are the goals of NTP?
• Why is microscopy an effective diagnostic technique?
• What is DOTS?
• What is the role of the laboratory in TB control?
Summary
75
References
1. PTSI,DOH,RITM,NTRL, Training Manual (Training course on Direct Sputum Microscopy
2. http://wwwn.cdc.gov/dls/ila/acidfasttraining/section1.aspx#training
3. International Standards for Tuberculosis Care, 2009
4. http://www.who.int/tb/strategy/en/
5. NTP MOP 2005