Transcript An Early Morning Sputum Sample Is Necessary for the Diagnosis of
An Early Morning Sputum Sample Is Necessary for the Diagnosis of Pulmonary Tuberculosis, Even with more Sensitive Techniques
: 4/26/2020 Willy Ssengooba Makerere University Kampala, Uganda Ssengooba, W. et al 2012 Tuberc. Resear &Treat 1
Background: TB in adolescents
• There is scant data on TB among adolescents in Uganda and worldwide.
• Reports indicate that many adolescents with active TB are diagnosed during late stage of the disease .
• It is quite challenging to obtain quality sputum samples, especially in community studies and vaccine trials where suspects may be identified at early stage of disease.
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Background: sputum samples
• The WHO and IUATLD recommended collection of two sputum samples for smear microscopy with at least one being an early morning (EM).
• Whereas the number and type of sputum samples required for smear microscopy is well known, the number and type of sputum samples required for culture have not been well standardized.
• Furthermore, while there is a significant diagnostic gain from EM sputum samples when using smear microscopy, it is not clear whether this gain remains significant when using more sensitive techniques such as culture particularly among adolescents.
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Background ctned
•
Objective:
to determine the diagnostic yield of the spot and the incremental diagnostic yield of EM sputum sample cultures for diagnosis of TB among adolescents in rural Uganda.
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Methods
Study Design and Setting.
• This study was a sub-component of a large observational cohort study undertaken by Makerere University School of Public Health, which enrolled 5000 adolescents in Iganga, rural Uganda, in preparation for TB vaccine trials ( 2009 2011). • The adolescents were assessed for TB at baseline and followed every 6 months for 1-2 years; and TB suspects were defined as having TB contact in the household
or
a TB symptom for 2 weeks or more.
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Methods ctned
• Sputum samples were obtained daily from the participants by nurses and transported in cold box (temperature
≤
8
◦
C) to a reference mycobacteriology laboratory (biosafety level 3) where culture and analysis were done. • The analysis included study participants with both EM and spot sputum samples submitted for culture.
•
Laboratory tests included
: Smear Microscopy (FM) and culture ( LJ &MGIT).
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Data analysis
• The primary outcome of our analysis was
culture positive TB case
, defined as MTBC positive upon LJ or MGIT culture from either spot or EM samples.
•
Diagnostic yield;
referred to the number of TB cases detected by each sputum sample type (spot or EM) irrespective of whether the comparator was positive. •
Incremental diagnostic yield;
referred to the yield of culture positive EM samples in terms of TB cases detected when the spot sample from the same case was negative. • Used Stata for analysis.
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Study Flow chart
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Results
• Screened 5000, enrolled 2418 participant.
• 1862 participant had both spot and EM samples • Six (0.3%) were positive by smear microscopy.
• 21 (1.1 %) were culture confirmed MTBC-positive. • 225 (12.1%) had MOTT on MGIT culture.
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Table 2: Mycobacterial yield from EM and spot sputum samples by different culture methods (n=1862) Culture method Results Spot samples EM samples EM and Total n (%) n (%) spot samples n (%) n (%) LJ [p< 0.001] MTBC positive
MOTT Culture negative
1 (0.1)
0 1831 (98.3) Contaminated 30 (1.61)
2 (0.1)
0 1806 (97.0) 54 (2.9)
3 (0.2)
0 1859 (99.8) 0
6 (0.3)
0 1772 (95.2) 84 (4.5)
MGIT [p<0.001] MTBC positive
MOTT
6 (0.3)
106 (5.7) Culture negative 380 (20.4) Contaminated 436 (23.4)
12 (0.6)
119 (6.4) 301 (16.2) 499 (26.8)
3 (0.2)
0 (0.0) 1859 (99.8) 0(0.0)
21 (1.1)
225 (12.1) 681 (36.6) 935 (50.2) 4/26/2020 10
Results ctned [n=21]
Culture method
LJ MGIT
Yield of spot n (%)
4 (19.0) 12 (57.1)
Incremental diagnostic yield for EM (observed) n (%) Total number of TB cases detected n (%) 2 (9.5) 9(42.9)
6 (28.6) 21 (100) LJ= Lowenstein Jensen, MGIT= Mycobacterial Growth Indicator Tube, EM, =Early Morning 4/26/2020 11
Discussions and conclusion
• EM sample culture has a high incremental diagnostic yield i.e.
9.5%
on LJ and
42.9%
on MGIT culture.
• Given the sensitivity of culture one would expect the incremental gain from EM to be negligible, but it is not.
• MGIT culture gives a higher MTBc yield , but also more MOTT and contamination.
• More studies to look at the impact of high proportion of MOTT in a TB vaccine trial perspective are needed.
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Benon B Asiimwe et al , 2013
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Acknowledgement
Funding:
• EDCTP • AERAS • Makerere University /IDI •
Co-authors: 1 (
Moses Joloba, Philippa Musoke, Harriet Mayanja-Kizza, James Waako, Anne Wajja, Benon Asiimwe & Lab team) • and
2
Suzanne Verver
1
Makerere University College of Health Sciences Kampala Uganda
2
KNCV Tuberculosis Foundation, The Netherlands
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