1. LIAQUAT
MEDICAL
UNIVERSITY
By:
DIAGNOSIS OF
TUBERCULOSIS
Assist: Prof:
Faculty of Community Medicine & Public Health
Sciences
Liaquat University of Medical & Health Sciences
(LUMHS)
Jamshoro, Sind, Pakistan
e mail mnajeeb80@gmail.com

3. Why diagnosis important?
 Diagnosis of tuberculosis in most cases
 clinical diagnosis based upon the clinical presentation
 In 15-20% of p’t with suspected TB
 lab confirmation never obtained
 Early diagnosis and initiation of effective
therapy
 reducing morbidity and mortality from TB
 minimize the spread of infection

4. Outline
 Screening for prior infection
 Tuberculin skin test
 Diagnosis of pulmonary TB
 Medical history
 Physical examination
 Chest radiograph
 Bacteriologic exam

5. Screening for prior infection
Tuberculin skin test
(little value as a case- finding tool )

6. Screening for prior infection
 Whom to screen
 Highprevalence and high risk population
(HIV)
 How to screen
 Mantoux tuberculin test (ie, purified protein
derivative or PPD, tuberculin skin test)
 How to interpret
 Determine maximum diameter of induration
by palpation

7. Mantoux Tuberculin Test
 Preferred method of testing for TB
infection in adults and children
 Tuberculin skin testing useful for
 Examining person who is not ill but may be
infected
 Determining how many people in group are
infected
 Examining person who has symptoms of TB

8. Mantoux test
 Inject intradermally
0.1 ml of PPD
tuberculin
 Produce wheal 6 mm
to 10 mm in diameter
 Represent DTH
(delayed type
hypersensitivity)

9. Reading of Mantoux test
 Read reaction 48-72
hours after injection
 Measure only
induration
 Record reaction in
mm

10. Classifying the tuberculin reaction
 >5 mm is classified as positive in
 HIV-positive persons
 Recent contacts of TB case
 Persons with fibrotic changes on CXR
consistent with old healed TB
 Patients with organ transplants and other
immunosuppressed patients

11. Classifying the tuberculin reaction
 >10 mm is classified as positive in
 Recent arrivals from high-prevalence
countries
 Injection drug users
 Residents and employees of high-risk settings
 Mycobacteriology laboratory personnel
 Persons with clinical conditions that place
them at high risk
 Children <4 years, or children and
adolescents exposed to adults in high-risk
categories

12. Classifying the tuberculin reaction
 >15 mm is classified as positive in
 Persons with no known risk factors for TB

13. Factors may affect TST
 False negative
 Faulty application
 Acute TB (2-10 wks to convert)
 Very young age (< 6 months old)
 Live-virus vaccination
 Overwhelming TB disease
 False positive
 BCG vaccination (usually <10mm by adulthood)
 Nontuberculous mycobacterial infection

14. Two-Step Testing
 Use two-step testing for initial skin testing
of adults who will be retested within 1-3
weeks
 If first test (+), consider the person infected
 If first test (-), give second test 1-3 weeks
later
 If second test (+), consider person infected
 If second test (-), consider person uninfected

15. Diagnosis of Pulmonary TB

16. Diagnosis of disease
 1.Medical
 1. Medical history  2. Laboratory
 2. Physical  Tuberculin
 X-ray exam:
examination  Mass miniature radiography
 3. Chest radiograph  Sputum exam:
 4. Bacteriologic exam  Sputum culture
 Biochemical test
 AFB  Luciferase assay
 Culture  ATP enzyme
 Blood C.P ( ESR
normocytic anemia and lymphopenia

17. 1. Medical History

18. 1. Medical History
 Symptoms of disease
 History of TB exposure, infection, or
disease
 Past TB treatment
 Demographic risk factors for TB
 Medical conditions that increase risk for TB
disease

19. Medical History
 High prevalence population
 More likely to be exposed to and infected with
bacillus
 Immigrant from high prevalence area
 Resident or worker in jail
 Long term care facility
 Close contact to p’t with active TB

20. Medical History
 High risk population
 More likely to progress from infection to active TB
 HIV (+) or other immunodeficiency
 CRF
 DM
 IVDA
 Alcoholics
 Malnourished
 Malignancy
 Gastrectomy

21. 2. Physical Examination

22. 2. Physical Examination
 Productive, prolonged cough
 duration of ~3 weeks
 Chest pain
 Haemoptysis
 Fever/Chills
 Night sweats
 Appetite loss
 Weight loss
 Easily fatigued

23. 3. Chest radiography

24. 3. Chest radiography
 Classical radiograph appearance
 Infiltration
 Cavitation
 Fibrosis with traction
 Enlargement of hilar and mediastinal lymph node
 In reactivation TB
 Classically fibrocavitary apical disease
 Primary TB
 Middle or lower lobe consolidation

25. Chest radiography
 Abnormalities often
seen in apical or
posterior segments of
upper lobe or superior
segments of lower
lobe
 May have unusual
appearance in HIV-
positive persons
 Cannot confirm
diagnosis of TB!!
cavity in patient‘s RUL
classic" for adult-type, reactivation tuberculosis

26. Classic adult TB CXR
 PA view
 diffuse parenchymal
disease with multiple
cavities and bulla
formation on the left
 Sputum smear was
positive for AFB

27. Chest radiography
 No chest X-ray pattern is absolutely typical
of TB
 10-15% of culture-positive TB patients not
diagnosed by X-ray
 40% of patients diagnosed as having TB
on the basis of x-ray alone do not have
active TB

28.  Mass miniature radiography:-
(By Who expert committee )
 Indiscriminate TB case finding by it should
be abandoned.

29. X-ray-based evaluation causes
over-diagnosis of TB
100
Over-
80 diagnosis
60
40
20
0
Diagnosed by X- Actual cases
ray alone
NTI, Ind J Tuberc, 1974

30. 4. Bacteriologic Exam

31. Specimen Collection
 Obtain 3 sputum specimens for
smear examination and culture
 Persons unable to cough up sputum
 induce sputum
 bronchoscopy
 gastric aspiration
 Follow infection control precautions during
specimen collection

32. Three Specimens
 Three specimens optimal
• Spot specimen on first visit; sputum container
given to patient
• Early morning collection by patient on next
day
• Spot specimen during second visit

33. Three sputum smears are optimal
100%
100% 93%
81%
Cumulative Positivity
50%
0%
First Second Third

34. Number of sputum samples required
 overall diagnostic yield for sputum
examination related to
 the quantity of sputum (at least 5 mL)
 the quality of sputum
 multiple samples obtained at different times
to the laboratory for processing
3 samples obtained at least eight hours apart with
at least one sample obtained in the early morning

35. Number of sputum samples required
 several studies have suggested that only
two samples may be sufficient to capture
the majority of cases:
 Retrospective study
 Nelson, SM, Deike, MA, Cartwright, CP. Value of examining multiple sputum specime
specim
 overall,
92 percent of cases would have
been detected with two specimens
a third sputum smear was of no
additional value

36. Smear Examination
 Strongly consider TB in patients with
s
smears containing acid-fast bacilli (AFB)
 Results should be available within 24
hours of specimen collection
 Presumptive diagnosis of TB
 Not specific for M. tuberculosis

37. AFB smear
AFB (shown in red) are tubercle bacilli

38. Reporting on AFB Microscopy
Number of bacilli seen Result reported
None per 100 oil immersion fields Negative
1-9 per 100 oil immersion fields Scanty, report
exact number
10-99 per 100 oil immersion fields 1+
1-10 per oil immersion field 2+
> 10 per oil immersion field 3+

39. Open tuberculosis
 A tuberculous ulceration or other
form of tuberculosis in which
tubercle bacilli are present in the
excretions or secretions.
 Pulmonary tuberculosis, especially
with cavitation.
 開放性結核就是在病人咳出的痰液中有結
核桿菌的存在

40. Sputum Cultures
 2nd in importance in case- finding programme.
 Difficult
 Tedious
 Expensive
 Needs special training
 lengthy ( takes at least 6 - 8 wks ) L. J media
 Method offered with chest symptoms & sputum
smear –ve.
 Culture of sputum is necessary for carrying out
sensitivity tests & monitoring drug treatment
( drug susceptibility test )

41.  Liquid media ( BACTEL media is used )
production of co2 in 2 wks

42. Cultures
•Gold standard for TB diagnosis
•Use to confirm diagnosis of TB
•Culture all specimens, even if smear negative
•Results in 4 to 14 days when liquid medium
systems used
Colonies of M. tuberculosis growing on media

43. Microscopy is more objective
and reliable than X-ray
Inter-observer
98%
100 agreement
80 70%
60
40
20
0
AFB Microscopy X-ray

44. Microscopy is a more specific test than
X-ray for TB diagnosis
100 98%
Specificity
80
60 50%
40
20
0
AFB Microscopy X-ray

45. Diagnosis of Pulmonary TB
Cough 3 weeks
If 1 positive,
AFB X 3 If 2/3 positive:
X-ray and Anti-TB Rx
evaluation
If negative:
Broad-spectrum antibiotic 10-14 days
If symptoms persist, repeat AFB smears, X-ray
If consistent with TB
Anti-TB Treatment

46. Recommended Diagnostic Approach

47. Thanks for your attention!