Diagnosis Of Tuberculosis Dr.T.V.Rao.Presentation Transcript
Robert Koch Discovers
A Global Emergency
The Tuberculosis in the
beginning of the 21st Century
declared as Global Emergency
Why Tuberculosis is a Important
Tuberculosis continues to be a
Important communicable disease.
A leading cause of morbidity and
mortality in Developing world.
Most Important communicable
disease in Bangladesh, China,
Indonesia, Africa, and Pakistan.
But it is Curable Disease
Tuberculosis is a Global Problem
Tuberculosis - Important
communicable disease spread by
Why Everybody Concerned.
Tuberculosis kills young adults.
Premature death of the infected a
Today many are co infected with HIV.
The open cases of Tuberculosis infects a
few around his/her environment.
A social burden to the family, society and
Tuberculosis in the era of
HIV / AIDS.
HIV / AIDS epidemic led to large
increase of Smear negative
pulmonary tuberculosis which in turn
has led to poor treatment out comes,
and early mortality
Frequently involves Lower lobes of
Why we fail to Diagnose
Lack of health infrastructure.
Control is plagued with lack of
Why we failed ( Cont )
Diagnostic services are poor, and so
we failed at Individual and
Patients are diagnosed late.
Many patients are never diagnosed
Early deaths are burden to
Social Infrastructure and
Importance of Clinical services
Early diagnosis rests with clinicians,
whose contribution is immense in
A clinicians knowledge, proper
documentation are immense help in
When to suspect Tuberculosis
Cough longer than 3 weeks.
Fever for 1 month, or both.
Blood stained sputum.
Night sweats, weight loss
Age between 14 and 70 years
( Correlates National Tuberculosis
Tuberculosis is a diversified disease.
Any organs can be involved.
Any age group, gender no bar for
Involvement of Lungs contribute to
majority of tuberculosis.
And involvement of Lungs is designated as
Diagnosis of Pulmonary
Majority of Adults suffer with pulmonary
Microbiological examination of Sputum
continues to be a Gold standard in proving
Sputum examination in Children is not
sensitive in Diagnosis.
Radiological examination of Lungs, most
commonly prescribed investigation.
X - ray examination of chest most
easily available Investigation.
Investigations are essential
for definitive Diagnosis of
Importance of Optimal Specimens
Pulmonary Tuberculosis is the
commonest presentation of
Sputum is the Most important
specimen for identification and
isolation of Acid fast bacilli.
The developing countries suffers the
most important step in getting an
Train the staff to obtain the appropriate
A few minutes of education to patients on
importance of ideal sample make a great
difference and improves the Diagnosis.
Observe to identify Sputum from
Specimens appear mucoid Appears clear, watery,
even, blood stained. and frothy.
Contains many squamous
Polymorphoneutrophils. Absence of
Role of Microscopy in Tuberculosis.
Microscopy for Diagnosis of Tuberculosis is
initiated in 1880
The conceptions have not changed since
Best efforts should be put to obtain
Processing of saliva loses all valuable clues
Microscopy and Tuberculosis
Ziehl – Neelsen’s
A century old
Only we need Microscope, and few
Most rapid, economical,
Can detect bacterial load.
A Diagnostic, and Prognostic tool.
A little of sputum 0.2 µl is adequate.
A prompt diagnosis after searching
as few as 100 fields.
Limitation of Microscopy for
Repeated sample examinations. load on
Training and dedication of Microscopist.
The load of bacilli must be more than
10,000 / 1 ml of sputum.
Low in sensitivity < 50 %
Repeated requests for samples
High drop out by patients, for repeated
Not dependable in pediatric age group.
Smear showing Acid Fast Bacilli.
What is Smear Positivity
All patients who have submitted
Specimens and found to be
for identification of AFB
Processing Direct smear negative
Sputum Microscopy can be improved with
Sputum liquefaction, concentration and
Benefits of Liquefaction and
Major studies showed processing of
sputum with chemicals and centrifugation
improved sensitivity up to 18 %.
Incremental yield ( positive with bleach
minus positives with Ziehl – Neelsen stain)
up to 9 %.
Treating specimens with Sodium
hypochlorite is Mycobactericidal and also
kills HIV and improves the safety and
acceptability by technical staff.
When Microscopy fails
Smear negative tuberculosis.
In HIV infected patients, on many
occasions prove negative. in spite of
presence of bacilli, ( as few bacilli are
Needs concentration and liquefaction
Time consuming, needs more
Growing role of
There is a growing need for screening for
AFB by Florescent Microscopy.
Several studies prove, Florescent
Microscopy in Diagnosis of Tuberculosis is
Developing world should opt and initiate
Acid Fast Bacilli as seen under
Why we need Florescent
Useful when few bacilli are present.
Increases the sensitivity in HIV patients with
Reduces the time needed for testing.
About 15 times as many fields of view can be
scanned by fluorescent microscopy than by Ziehl –
Neelsen’method in the same period.
Increases the sensitivity by 10 %
Better conclusions with one or two specimens,
unlike Ziehl Neelsen’s method needing 3 or > 3
Culturing for isolation of
Mycobacterium spp continues to be a
Gold standard, particularly in
Need only 10 – 100 bacilli / 1 ml of
Most useful in
Drug sensitivity testing patterns.
Identify treatment failures.
Useful in Patients presenting with
respiratory symptoms, X- ray’s
suggestive, but smear negative. Can prove
Cultures remain suggestive and helpful in
early treatment periods, failed drug
Methods of Culturing.
Culturing on Lowenstein Jenson’s
culture medium remain the
affordable ,economical method in
Limitation in Culturing
Mycobacterium spp are slow
Need 6 – 8 weeks for growing.
Specimens can be contaminated
while growing, needs repeated
specimens, in turn patients loose
confidence in Laboratories.
Recent facts on Culturing
Useful in HIV infected patients with
As even few bacilli can be grown in
spite of smear negativity.
But the specimens to be incubated
for longer time as few bacilli are
Pitfalls in Culturing
Specificity is lost due to
Can yield false positive results in 1 –
4 % of the cases.
Cultures may be negative in spite of
x rays are suggestive of tuberculosis.
Growth of Acid fast bacilli on
L J Medium.
There are emerging Modern Media
with accurate detection, are
replacing the Egg and Agar based
Emerging methods in Culturing
MGIT – Mycobacterium growth
incubator tube method.
Growth occurs in shorter than egg
Usefulness in HIV patients
Contamination is less
But expensive to people in
Blood culturing for Mycobacterium
Useful in HIV patients, and children.
Effective in isolation of Atypical
But not cost effective.
May be important tool in future for
diagnosing Tuberculosis in HIV
Molecular Methods in
Diagnosis of Tuberculosis
Several methods are
available, mainly used as
Real Time PCR replacing older
PCR How useful to our Patients?
PCR ( Polymerase chain reaction ) used by
However most cases can be diagnosed
with simple methods if effectively used.
The definite role of PCR continues to be
Above all not cost effective to Developing
Rapid Diagnostic Methods
Past decade has seen several
How far practicable ?
Emerging Rapid Methods.
1. Fast Plaque TB uses phage amplification
2. ELISA ( QuantiFERON – TB )
3. Enzyme-Linked immunospot
( ELISPOT )
ELISPOT proved highly useful to detect active
tuberculosis in Adults and children.
Microscopic observation drug susceptibility
assay. ( MODS )
A new method gained importance in
Use a tissue culture plate based assay
with use of Middle Brook 7HG.
Needs a inverted light microscope.
Even the drug resistance can be tested
with Rifampicin,and Isoniazid.
Safe to work with cultures.
Non Specific Tests
( Mantoux Test )
( Mantoux Test )
Test to be interpreted
in relation to clinical
Even the induration of
5 mm to be considered
positive when tested
on HIV patients.
Serology in Tuberculosis.
Several serological methods were
But never gained the acceptance of
the majority of the clinicians.
Serological tests are low sensitivity.
Many physicians depend on serology
in extra pulmonary tuberculosis.
Dealing with Tuberculosis
in HIV / AIDS patients.
Diagnosing Tuberculosis in
HIV infected is a priority and
improve quality of Life
HIV/AIDS - Tuberculosis
Consider the HIV status
Identify the severity of Tuberculosis.
Early use of chest radiography.
Maximal number of sputum smear
Sputum concentration methods to be
encouraged even by smaller laboratories.
Explore the use of Florescent Microscopy.
All smear negative specimens should be
Limitations of Rapid Tests
The testing needs advanced and
These tests are known for their
inability to diagnose between active
disease and latent infection.
Exclusively used in Developed
Poses several challenges, Yet
no optimal, specific diagnostic
Extra pulmonary Tuberculosis
A real challenge to Clinicians and
Optimal specimen collection a priority,
Molecular Methods are growing need.
Clinicians start drug regimes on empirical
Several serological tests for antibody
determinations are evaluated.
Identification of Atypical
A growing concern on infections with less
known, uncommon Mycobacterium in
immunosupreesed, an emerging
infectious disease problem
Needs the help of reference
Needs different drug regimes, unlike
typical Mycobacterium isolates.
Now a gowning concern in the era of
It is highly essential to explore and discover rapid,
simple, and accurate tuberculosis diagnostic tools.
A massive investment, greater scientific interest,
political commitment a top priority,
Man power development, Human resource
utilization a greater concern.
Microscopy and Florescent Microscopy utilization
should be immediate concern, and strengthening
of treatment initiation protocols.
Effective methods in diagnosing smear negative
patients a growing priority.
Microscopy in Tuberculosis
In spite of several
continues to be
back bone in
Specific detection of active
Tuberculosis cases in
patients with HIV infection or
AIDS is feasible and
improves the rate of early
diagnosis and successful
treatment of Tuberculosis.
Created for Medical graduates and
Health care workers in Developing world
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