Highlights
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OM-S is safe for using as sputum transportation reagent.
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‘OM-S treated’ sputum is compatible to test with Xpert and culture.
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Primary contamination rate of culture was lower (p < 0.05) in ‘OM-S treated’ portion.
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‘OM-S treated’ sputum does not require centrifugation for Xpert testing.
Keywords: OMNIgene.SPUTUM, Sputum transportation, Room temperature, Tuberculosis
Abstract
Background
Performance of OMNIgene.SPUTUM (OM-S) for transporting sputum was evaluated.
Methods
This exploratory study was conducted during January-December 2019 at four near and one distant healthcare-facilities of Dhaka. Smear-positive pulmonary TB patients’ sputa were collected, divided into ‘OM-S untreated’ and ‘OM-S treated’ portions, and transported to testing laboratory, Dhaka, on same-day from near-sites, and through courier from distant-site for smear-microscopy, culture, and Xpert MTB/RIF (Xpert) testing. Subset of ‘OM-S treated’ sample was tested with Xpert without centrifugation. Test results of all portions were compared in between.
Results
Total 444 participants were enrolled (near-sites:198, distant-site: 246). All test results were comparable in both portions for near-sites. For distant-site, smear-microscopy’s positivity was reduced by 4.1 % in ‘OM-S treated’, Xpert showed 100 % concordance in both portions, and culture was higher in ‘OM-S treated’ than ‘OM-S untreated’ (92.3 % vs 89.4 %; p = 0.288). Primary contamination rate in ‘OM-S treated’ was lower than ‘OM-S untreated’ (2.0 % vs 9.8 %; p < 0.05). For all sites, median (IQR) time-to-culture positivity was 35 (28, 42) days in both portions. Xpert positivity was 99 % concordant in ‘OM-S treated’ regardless of centrifugation.
Conclusions
OM-S is safe for sputum transportation. OM-S mixed sputum can be tested with Xpert and culture. Further studies can validate findings and assess cost-effectiveness.
1. Introduction
Globally, tuberculosis (TB) remains one of the principal reasons of death [1]. Despite advances in TB control, Bangladesh is still on the list of high TB and multidrug-resistant (MDR)-TB burden countries. In 2023, TB incidence was assumed to be 221 per 100,000 population and around 5,000 people were estimated to be MDR/Rifampicin resistant (RR)-TB in Bangladesh [2]. Although 302,813 people with TB (PWTB) were notified to the National TB Control Programme (NTP) in same year, over 76,000 (20 %) were missed [2].
Deficiency of highly sensitive laboratory diagnostics at all peripheral laboratories might be an important reason for missing PWTB [3]. Currently, over 1,000 microscopy centers are functional across Bangladesh, however, due to less sensitivity, PWTBs often remain undetected by smear microscopy for acid-fast bacilli (AFB) [4]. Mycobacterial culture is ‘gold standard’ to detect viable Mycobacterium tuberculosis (MTB) in sputum samples, and considered as an outcome indicator for both PWTB and MDR-TB [5]. Nevertheless, modern laboratory setups and expert technicians are required to perform culture, which is difficult to ensure at all laboratories, especially in under-resourced countries. Currently, in Bangladesh, culture is available at national and regional reference laboratories, and specific diagnostic centres [6,7]. World Health Organization (WHO) recommended rapid and highly sensitive molecular test, Xpert MTB/RIF assay (Xpert), to detect MTB along with susceptibility of Rifampicin, one MDR-TB indicator, within two hours [8]. Though NTP has expanded Xpert facilities nationwide, the coverage is still up to primary healthcare facilities [4]. These advanced diagnostics are not always accessible to people from remote areas, which hinders timely detection and increases risk of disease transmission. To overcome all these challenges, an effective sputum transportation tool can be an alternative.
‘OMNIgene-SPUTUM (OM-S; DNA Genotek Inc., Ottawa, ON, Canada), a transportation reagent for sputum, liquifies and purifies sputum samples, and retains MTB viable up to eight days till temperature of 40⁰C [9]–[11]. OM-S-mixed sputum does not necessitate cold chain during transportation, and is also suitable for testing with various conventional and molecular investigations for TB [9,12]. Studies from Africa exhibited similar findings on Xpert test in OM-S mixed and unmixed sputum samples following standard of care transportation method [10,13,14]. OM-S is effective to inhibit growth of bacterial contaminants in sputum and can preserve viability of mycobacteria for up to eight days, however, this reagent delays culture positivity [10,11]. Previous studies revealed capability of using ‘OM-S treated’ sputum for all available TB-specific laboratory tests performance [10,11]. Several studies exhibited higher positivity and low contamination rates in solid culture (using L-J media) in ‘OM-S treated’ samples [9,10,12,15]. In 2017, WHO’s Technical Expert Group recommended further studies to remark on OM-S reagent and providing approval [16]. Our study assessed the performance of OM-S in a resource-limited country like Bangladesh to transport sputum to referral laboratories to improve TB detection.
2. Methods
2.1. General setting
Bangladesh is a densely populated, middle-income country in South Asia, with over 165,000,000 population [17]. It has eight divisions comprising of total 64 districts, and Dhaka is the capital [18].
2.2. Study setting, design, and duration
This methodology was adopted from Research for Decision Makers (RDM) Activity report [19]. This exploratory study was conducted between January and December 2019 at five healthcare facilities. For evaluating the effect of OM-S on sputum, four (one district and three sub-district) healthcare facilities, situated between 19 and 43 km away from the capital, Dhaka, were selected. From these sites, sputum samples were transported within the same day to testing laboratory. To examine the performance of OM-S for transporting sputum from distant site, we selected Chest Disease Clinic (CDC), Chattogram, which is 250 km away from Dhaka. Sputum samples were transported by courier to testing laboratory. All facilities were equipped with physicians, pathology lab, radiology department, and Directly Observed Treatment (DOT) centres, where smear microscopy/Xpert testing facilities were available. Over 100 individuals visit these facilities every day to seek healthcare services.
2.3. Study population, sample size, and enrolment details
Smear-positive pulmonary TB (PTB) patients of ≥ 15 years old, diagnosed at DOT centres of selected healthcare facilities, were enrolled after receiving appropriate consent/assent. Patients taking anti-TB treatment or unable to provide adequate sputum or did not provide consent were not enrolled. The icddr,b-recruited Field Assistant (FA) interviewed eligible participants to collect required information. Our calculated sample size for evaluating effectiveness of OM-S for transporting sputum samples was 200 smear-positive PTB patients, assuming enrollment of 15 smear-positive eligible PTB patients each month from four field sites near Dhaka during study period. However, for investigating performance of OM-S for increased MTB detection, the calculated sample size was 225 with an assumption of improving MTB detection among ‘OM-S treated’ sputum samples by 10 % at 95 % confidence interval (CI) with 80 % power, and considering ∼ 15 % incomplete data or drop-out [20]. Total of 444 PTB patients were enrolled from selected hospitals during study period.
2.4. Collection and transportation of sample
We collected 5 mL of fresh sputum sample from each enrolled participant in a sterile container, divided into two identical portions (2.5 mL each), and marked as ‘portion-1′and ‘portion-2′. We mixed ‘portion-1′ with OM-S (OM-S treated) in 1:1 proportion whereas ‘portion-2′ were kept OM-S untreated (OM-S untreated). The OM-S reagent was mixed with sputum using vortex mixer. At field sites, ‘OM-S untreated’ samples were stored in cool boxes (ice-bags in situ) temporarily to maintain 2-8⁰C temperature and ‘OM-S treated’ sputum samples were preserved in a box at room temperature. For the subset group, we collected 6 mL of sputum (3.5 mL in ‘portion-1′ and 2.5 mL in ‘portion-2′). One mL of ‘portion-1′ i.e. ‘OM-S treated’ sputum was parted into another pot, marked as ‘portion-3′, and stored with ‘OM-S untreated’ sputum sample in same box at room temperature. Samples were transported or couriered (‘OM-S treated’ without cold chain and ‘OM-S untreated’ with cold chain) to testing laboratory daily for further testing. Temperature monitor was put inside the transportation box to record temperature after reaching the laboratory. We also recorded the time during sample collection at field site and when it arrived at laboratory.
2.5. Laboratory procedures
All samples were tested with smear for AFB microscopy, Xpert and solid culture; ‘portion-3′ was tested with Xpert only following same procedure but ‘without centrifugation’. Sample processing and testing procedures have been detailed in Supplementary File-1.
2.6. Delivery of laboratory test results and anti-TB treatment
As we enrolled smear-positive PTB patients, all were registered for anti-TB treatment at respective DOT centres following national guideline. We provided results of laboratory tests performed under study to the local physicians and participants as per availability.
2.7. Data collection and variables
The FAs collected data on socio-demography (age/sex/contact information/address) and presence of TB symptoms for example, cough (yes/no), fever (yes/no), loss of appetite (yes/no), night sweats (yes/no) and weight loss (yes/no). Data were also documented on laboratory test results of both ‘OM-S untreated’ and ‘OM-S treated’ portions at testing laboratory: smear microscopy (positive/negative), Xpert (MTB detected/MTB not detected); culture (positive/negative/primary contamination/secondary contamination); and ‘Xpert without centrifugation’ results of a subset of ‘OM-S treated’ portion (MTB detected/MTB not detected). Both field and laboratory data were checked after collection. Data consistency was checked by matching with questionnaire and by re-interview if required. Data were entered separately in Statistical Package for the Social Sciences (SPSS) version 20.0, checked for quality, merged and cleaned for analyses.
2.8. Statistical analysis
SPSS, version 20.0 was used for data analyses. Proportions were used for summarizing symptoms and socio-demographic details. For each of the laboratory tests of ‘OM-S untreated’ and ‘OM-S treated’ sputum, we developed 2x2 tables. Near to Dhaka sites, from where samples were transported within same day, has been labelled as ‘same-day transportation’ and CDC, Chattogram, or distant site as ‘distant transportation’ sites. We considered “primary contamination” if contamination was found during sample processing for culture at testing laboratory firstly, after transportation from field sites. Performance of OM-S was compared by measuring concordance and discordance of each test performed in ‘OM-S treated’ and ‘OM-S untreated’ sputum. Requirement of centrifugation before Xpert testing was assessed by comparing the Xpert results of 'portion-1' (with centrifugation) and 'portion-3' (without centrifugation). We used t-test to compare the difference between two rates. P value of < 0.05 at 95 % confidence interval was considered as statistically significant.
2.9. Ethical statement
We interviewed participants after taking informed written consent from adult (≥18 years old) participants, and assent from both participants and their guardians for 15–17 years age group. We strictly maintained confidentiality of participants and kept data anonymous so that they could not be identified. Only concerned health personnel, implementer and respondents/participants have access to anonymous data.
3. Results
3.1. Baseline characteristics
Among enrolled, 198 were from near Dhaka and 246 were from distant site. Mean (±SD) age of participants was 38.7 (±16.0) years and male to female ratio was 2:1. Of all, 443 (99.8 %) had more than 2 weeks cough, 322 (72.5 %) complained of weight loss and 435 (98.0 %) had more than 2 weeks fever. Participants’ demographic and clinical details have been stated in Table 1.
Table 1.
Demographic and clinical profiles of smear-positive PTB patients enrolled from selected health care facilities in Dhaka, Bangladesh between January and December 2019, N = 444.
| Characteristics | Number (N = 444) | Percentage (%) |
|
|---|---|---|---|
| Age in year | |||
| Mean ± SD: 38.7 ± 16.0 | |||
| Gender | |||
| Male | 298 | 67.1 | |
| Female | 146 | 32.9 | |
| Cough | |||
| Up to 2 weeks | 1 | 0.2 | |
| More than 2 weeks | 443 | 99.8 | |
| Fever | |||
| No fever | 1 | 0.2 | |
| Up to 2 weeks | 8 | 1.8 | |
| More than 2 weeks | 435 | 98.0 | |
| Other symptoms | |||
| Loss of appetite | 415 | 93.5 | |
| Night sweats | 426 | 95.9 | |
| Weight loss | 322 | 72.5 | |
| Haemoptysis | 31 | 7.0 | |
| Chest pain | 319 | 71.8 | |
| Shortness of breath | 172 | 38.7 | |
| Previous history of TB | 24 | 5.4 | |
| History of contact of TB in family | 79 | 17.8 | |
OM-S – OMNIgene.SPUTUM; TB – Tuberculosis; PTB − Pulmonary tuberculosis; % − Column percentage; SD − Standard deviation
3.2. Findings of laboratory test in ‘OM-S treated’ and ‘OM-S untreated’ sputum samples
3.2.1. Same-day transportation
For transportation on same day (n = 198), 190 (95.6 %) ‘OM-S treated’ and 192 (96.9 %) ‘OM-S untreated’ sputa were positive by smear microscopy (concordance: 97.9 %). Conversely, 184 (94.4 %) ‘OM-S treated’ and 186 (95.4 %) ‘OM-S untreated’ samples showed positive result on culture (concordance: 96.9 %) (Table 2). Median (IQR) time to culture positivity was 35 (28, 42) days in both portions; 12 (6.1 %) ‘OM-S treated’ and 11 (5.6 %) ‘OM-S untreated’ sputum showed primary contamination (p = 0.960). All (n = 198) ‘OM-S treated’ sputum samples showed positive result on Xpert, while, 197 (99.5 %) ‘OM-S untreated’ samples were positive on this test (concordance 99.5 %) (Table 2).
Table 2.
Test-to-test comparison between ‘OM-S treated’ and ‘OM-S untreated’ sputum samples collected from smear-positive TB patients enrolled from selected health care facilities of near to Dhaka, Bangladesh between January and December 2019, N = 198.
| Test methods | ‘OM-S treated’ sputum | ‘OM-S untreated’ sputum |
Positivity rate |
P-value |
Concordance |
|||
|---|---|---|---|---|---|---|---|---|
| Neg n (%) |
Pos n (%) |
Total n (%) |
OM-S (%) | ‘OM-S untreated’ (%) |
% |
|||
| AFB microscopy | Neg | 5 (83.3) | 3 (1.6) | 8 (4.0) | 96.0 | 97.0 | 0.595 | 97.9 |
| Pos | 1 (16.7) | 189 (98.4) | 190 (96.0) | |||||
| Total | 6 (100.0) | 192 (100.0) | 198 (100.0) | |||||
| Culture | Neg | 7 (77.8) | 4 (2.2) | 11 (5.6) | 94.4 | 95.4 | 0.662 | 96.9 |
| Pos | 2 (22.2) | 182 (97.8) | 184 (94.4) | |||||
| Total | 9 (100.0) | 186 (100.0) | 195* (100.0) | |||||
| Xpert | Neg | 0 (0.0) | 0 (0.0) | 0 (0.0) | 100.0 | 99.5 | 0.319 | 99.5 |
| Pos | 1 (100.0) | 197 (100.0) | 198 (100.0) | |||||
| Total | 1 (100.0) | 197 (100.0) | 198 (100.0) | |||||
*Three sputum in both portions showed contamination repeatedly, therefore, excluded from analysis.
OM-S- OMNIgene.SPUTUM; Neg-Negative; Pos-Positive; TB – Tuberculosis; % − Column percentage.
3.2.2. Distant transportation
The mean (±SD) time required for sample transportation from distant site (n = 246) was 3.1 (±1.3) days. Of all, 229 (93.1 %) ‘OM-S treated’ and 239 (97.2 %) ‘OM-S untreated’ sputa were positive on smear microscopy (Table 3). On culture, 227 (92.3 %) ‘OM-S treated’ and 220 (89.4 %) ‘OM-S untreated’ samples showed positive result with 3 % increased positivity among ‘OM-S treated’ samples (p = 0.288). For both portions, median (IQR) time to culture positivity was 35 (28, 42) days; 5 (2.0 %) ‘OM-S treated’ and 24 (9.8 %) ‘OM-S untreated’ sputum showed primary contamination (p < 0.05). In each portion, 245 (99.6 %) were Xpert positive and one was negative suggesting 100 % concordance (Table 3).
Table 3.
Test-to-test comparison between ‘OM-S treated’ and ‘OM-S untreated’ sputum samples collected from smear-positive TB patients enrolled from CDC, Chattogram, Bangladesh between January and December 2019, N = 246.
| Test methods | ‘OM-S treated’ sputum | ‘OM-S untreated’ sputum |
Positivity rate |
P-value |
Concordance |
|||
|---|---|---|---|---|---|---|---|---|
| Neg n (%) |
Pos n (%) |
Total n (%) |
OM-S treated (%) |
OM-S untreated (%) |
% |
|||
| AFB microscopy | Neg | 3 (42.9) | 14 (5.9) | 17 (6.9) |
93.1 |
97.2 |
92.7 |
|
| Pos | 4 (57.1) | 225 (94.1) | 229 (93.1) | 0.038 | ||||
| Total | 7 (100.0) | 239 (100.0) | 246 (100.0) | |||||
| Culture | Neg | 10 (38.5) | 9 (4.1) | 19 (7.7) |
89.8 |
|||
| Pos | 16 (61.5) | 211 (95.9) | 227 (92.3) | 92.3 | 89.4 | 0.288 | ||
| Total | 26 (100.0) | 220 (100.0) | 246 (100.0) | |||||
| Xpert | Neg | 1 (100.0) | 0 (0.0) | 1 (0.4) |
100.0 |
|||
| Pos | 0 (0.0) | 245 (100.0) | 245 (99.6) | 99.6 | 99.6 | − | ||
| Total | 1 (100.0) | 245 (100.0) | 246 (100.0) | |||||
OM-S – OMNIgene.SPUTUM; TB – Tuberculosis; Neg −Negative; Pos −Positive; OM-S − OMNIgene.SPUTUM; % − Column percentage.
3.3. Results of Xpert in centrifuged and diluted ‘OM-S treated’ samples
3.3.1. Same-day transportation
Among subgroup (n = 100) of sputum samples, 99 (99.0 %) showed positive result on Xpert irrespective of centrifugation with 99.0 % concordance. One sputum showed positive result on Xpert when centrifuged, however, was negative when diluted (Table 4).
Table 4.
Comparison of Xpert MTB/RIF assay between centrifuged and diluted ‘OM-S treated’ sputum samples collected from smear-positive TB patients enrolled from selected health care facilities situated near to Dhaka, Bangladesh between January and December 2019, N = 100.
| Diluted ‘OM-S treated’ sputum |
Centrifuged ‘OM-S treated’ sputum |
Positivity rate |
P-value |
Concordance |
|||
|---|---|---|---|---|---|---|---|
| Xpert | Neg n (%) |
Pos n (%) |
Total n (%) |
Diluted (%) |
Centrifuged (%) |
% |
|
| Neg | 0 (0.0) | 1 (1.0) | 1 (1.0) | 99.0 | 100.0 | 0.317 | 99.0 |
| Pos | 0 (0.0) | 99 (99.0) | 99.0 (99.0) | ||||
| Total | 0 (0.0) | 100 (100.0) | 100 (100.0) | ||||
OM-S – OMNIgene.SPUTUM; TB – Tuberculosis; Neg −Negative; Pos −Positive; % − Column percentage.
3.3.2. Distant transportation
Only one sputum among subset (n = 106) showed positive result on Xpert when centrifuged, however, exhibited ‘error’ when diluted. Of the rest 105 samples, 104 (98.1 %) were positive and one sputum was negative on Xpert irrespective of centrifugation (concordance 100.0 %) (Table 5).
Table 5.
Comparison of Xpert MTB/RIF assay between centrifuged and diluted ‘OM-S treated’ sputum samples collected from smear-positive TB patients enrolled from CDC, Chattogram, Bangladesh between January and December 2019, N = 106.
| Diluted ‘OM-S treated’ sputum |
Centrifuged ‘OM-S treated’ sputum |
Positivity rate |
P-value |
Concordance |
|||
|---|---|---|---|---|---|---|---|
| Xpert | Neg n (%) |
Pos n (%) |
Total n (%) |
Diluted (%) |
Centrifuged (%) |
% |
|
| Neg | 1 (100.0) | 0 (0.0) | 1 (0.9) | 98.1 | 100.0 | 0.159 | 100.0 |
| Pos | 0 (0.0) | 104 (100.0) | 104 (98.1) | ||||
| Total | 1 (100.0) | 104 (100.0) | 105* (100.0) | ||||
*One sputum was positive on Xpert while centrifuged but error while diluted.
OM-S – OMNIgene.SPUTUM; TB – Tuberculosis; Neg − Negative; Pos-Positive; % − Column percentage.
4. Discussions
This study, for the first time in Bangladesh, evaluated the effect of OM-S reagent on sputum samples as well as its effectiveness for transporting sputum from distant areas without cold chain. Our major findings exhibited that i) OM-S has no effect on sputum quality when mixed with it; ii) For distant transportation, primary contamination rate of culture in ‘OM-S treated’ sample was significantly lower, however, positivity rate of culture was not significantly increased; iii) Time to culture positivity, in both portions, was comparable; and, iv) Similar Xpert results in ‘OM-S treated’ sputum samples irrespective of centrifugation.
The same-day transportation arm aimed to see if there was any discrepancy between the test results ‘OM-S treated’ and ‘OM-S untreated’ portions that could stipulate any effect of OM-S on sputum sample. In this study, all test results were found to be comparable in both portions, nevertheless, culture positivity was slightly (1.0 %) reduced in ‘OM-S treated’ samples. Our result signified that OM-S reagent is safe for sputum. We did not find studies specifically mentioning its safety on sputum, however, this was reported as safe, and previous studies have not reported any adverse reaction regarding OM-S on sputum during distant transportation [9,11,21].
This study exhibited significantly lower primary contamination rate of mycobacterial culture in ‘OM-S treated’ samples transported from distant site. Previous studies showed similar findings where OM-S mixed samples showed reduced contamination rate in solid culture [9,12]. Our other observation was increased culture positivity in ‘OM-S treated’ sample transported from distant sites, which was concordant with previous studies [12,20]. This study also reported only 3.0 % increased culture positivity rate in ‘OM-S treated’ sputum than ‘OM-S untreated’ one. However, studies conducted in Nepal and Mozambique reported 9.0 % and 56.0 % increased culture positivity respectively in OM-S treated samples. The possible reasons for more positivity in those studies might be due to differences in sample transportation time and procedure. The transportation time of Nepal study varied up to 8 days and samples were transported without cold chain. In Mozambique study, samples were transported to central lab within same day, OM-S treated samples were incubated at room temperature and tested after 5 days. Whereas, our mean sample transportation time was around 3 days and we transported the OM-S treated samples without cold chain and the untreated samples with cold chain. If we had selected more remote or distant areas, positivity rate of culture may have been higher in ‘OM-S treated’ sample.
The other significant finding was that, there was no delay observed in time to culture positivity in ‘OM-S treated’ samples. The median transportation time for both same-day and distant sites, and for both ‘OM-S treated’ and ‘OM-S untreated’ sputum was similar (35 days). Study performed in Maputo also did not find any significant difference in culture positivity time for OM-S treated and untreated sputum for same-day arm, however, in five-day arm, OM-S treated sputum required one week longer time for culture positivity than the untreated one [12,15].
Regarding Xpert, we observed similar results in ‘OM-S treated’ sample regardless of centrifugation in same-day and distant transportation arms. Only one sputum resulted in ‘error’ while diluted, however, positive while centrifuged. Earlier, WHO suggested centrifugation of ‘OM-S treated’ sputum before Xpert testing in order to avoid dilutionary effect [22]. However, findings from current study suggests testing of ‘OM-S treated’ sputum with Xpert directly without centrifugation. It eliminates necessity of centrifuge machine at Xpert sites for processing ‘OM-S treated’ sputum which is expensive and difficult to install at laboratories. Our study also revealed similar results (100 % positivity) on Xpert in both ‘OM-S treated’ and ‘OM-S untreated’ portions for both same-day and distant transportations. This finding was concordant with previous studies [10,13,14].
Another observation was lower positivity rate of smear microscopy (decreased by 4.1 %) in ‘OM-S treated’ sputum transported from distant transportation site. This finding was similar to previous studies conducted in Ghana and elsewhere [13,16].
We had some limitations in this study. Firstly, no remote area was included. Secondly, OM-S was not compared to other available transportation reagents, for instance, Cetylpyridinium Chloride. Moreover, we only performed solid culture, not the rapid one (Mycobacteria Growth Indicator Tube i.e. MGIT), and did not evaluate the effectiveness of OM-S in smear-negative and extra-pulmonary samples which are paucibacillary in nature.
5. Conclusions
OM-S itself has no side effect on sputum. It has been found useful for transporting sputum to reference laboratories from point-of-care sites and can be tested with molecular test i.e. Xpert. Mixing OM-S with sputum could also be beneficial to perform culture at low contamination rate, which is routinely done during follow-up of MDR-TB patients.. Nevertheless, large-scale studies are essential including remote areas for validating the findings and, for assessing cost-effectiveness to use this reagent in wide-range.
Ethical approval
The research protocol (PR-17098) was approved by the Institutional Review Board of icddr,b constituting Research Review Committee and Ethical Review Committee.
Funding sources
This study was produced with the support of the United States Agency for International Development (USAID) under the terms of USAID’s Research for Decision Makers (RDM) Activity cooperative agreement no. AID-388-A-17–00006. Views expressed herein do not necessarily reflect the views of the U.S. Government or USAID.
CRediT authorship contribution statement
Senjuti Kabir: Writing – review & editing, Writing – original draft, Supervision, Project administration, Methodology, Investigation, Formal analysis, Data curation, Conceptualization. Sabrina Choudhury: Writing – review & editing, Writing – original draft, Supervision, Project administration, Formal analysis. Mohammad Khaja Mafij Uddin: Writing – review & editing, Project administration, Methodology, Investigation. M.D. Fahim Ather: Writing – review & editing, Writing – original draft, Investigation. Syed Mohammad Mazidur Rahman: Writing – review & editing, Investigation. Pronab Kumar Modak: Writing – review & editing, Project administration. Mohammad Samsuddoha Sarker Shanchay: Writing – review & editing, Project administration. Tanjina Rahman: Writing – review & editing, Formal analysis, Data curation. Shahriar Ahmed: Writing – review & editing, Supervision, Project administration, Conceptualization. Sayera Banu: Writing – review & editing, Supervision, Project administration, Methodology, Funding acquisition, Conceptualization.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
We are grateful to the authorities and physicians of participating hospitals to support us in performing research activities at their facilities especially for patients’ enrolment, data collection and ensuring sample collection. icddr,b is also grateful to the Governments of Bangladesh, and Canada for providing unrestricted/institutional support.
Footnotes
Supplementary data to this article can be found online at https://doi.org/10.1016/j.jctube.2025.100552.
Contributor Information
Senjuti Kabir, Email: senjuti.kabir@icddrb.org.
Sabrina Choudhury, Email: sabrina.choudhury@icddrb.org.
Mohammad Khaja Mafij Uddin, Email: kmuddin@icddrb.org.
M.D. Fahim Ather, Email: fahimather1993@gmail.com.
Syed Mohammad Mazidur Rahman, Email: smmazidur@icddrb.org.
Pronab Kumar Modak, Email: pronab.modak@yahoo.com.
Mohammad Samsuddoha Sarker Shanchay, Email: dr.doha36m@gmail.com.
Tanjina Rahman, Email: tanjina.rahman@icddrb.org.
Shahriar Ahmed, Email: shahriar.ahmed@icddrb.org.
Sayera Banu, Email: sbanu@icddrb.org.
Appendix A. Supplementary data
The following are the Supplementary data to this article:
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