Effect of active case finding on prevalence and transmission of pulmonary tuberculosis in Dhaka Central Jail, Bangladesh

Diagnostic accuracy of active pulmonary tuberculosis screening during detention admission: a systematic review

Individuals entering incarceration are at high risk for infectious diseases, other ill conditions, and risky behavior. Typically, the status of active pulmonary tuberculosis (PTB) is not known at the time of admission. Early detection and treatment are essential for effective TB control. So far, no study has compared the diagnostic accuracy of various TB screening tools in detention using a network meta-analysis (NMA). We aimed to investigate the diagnostic accuracy of active PTB screening tests upon detention admission. We searched PubMed, Global Index Medicus, the Cochrane Library electronic databases, and grey literature for publications reporting detention TB entry screening in March 2022 and January 2024. Inclusion was non-restrictive regarding time, language, location, reference standards, or screening tests. Eligible study designs comprised comparative, observational, and diagnostic studies. Publications had to report TB screening of individuals entering confinement and provide data for diagnostic accuracy calculations. The QUADAS-2 tool was designed to assess the quality of primary diagnostic accuracy studies. This systematic review was registered with PROSPERO (CRD42022307863) and conducted without external funding. We screened a total of 2,455 records. Despite extensive searching, no studies met our inclusion criteria. However, we identified evidence revealing key differences in screening algorithm application. In conclusion, more diagnostic accuracy data on TB screening algorithms for detention admission worldwide needs to be collected. We recommend that global TB initiatives set up multi-site studies to investigate the diagnostic accuracy of TB screening on admission in low- and high-prevalence criminal justice systems. Further network meta-analyses of these studies could inform policymakers and public health experts to establish or fine-tune TB control in detention settings.

Epidemiology of TB in prisoners: a metanalysis of the prevalence of active and latent TB

BACKGROUND

Tuberculosis (TB) in prisons usually occurs at higher rates than in the general population, especially in developing countries. TB has been reported as the most common cause of death among prisoners. Studies have shown limitations for early detection of TB in prisons that seem to result from mistaken concepts about TB, delayed diagnosis mainly due to the naturalization of lack of healthcare for this population METHODS: A scoping review was performed using the methodology of the Joanna Briggs Institute to assess "What are the scientific evidences on the epidemiology of TB in the prison system?". Then, a meta-analysis was performed to assess the prevalence of TB (active and latent) TB in prisoners. The results are presented as prevalence, in percentage, through random effects models, with a confidence interval of 95%.

RESULTS

Regarding active TB, the results of the metanalysis showed that countries with a high burden of TB had a prevalence of 3.54% [2.71; 4.63], countries not considered to be high burden TB countries had a prevalence of 1.43% [0.86; 2.37]. Latent TB had a prevalence of 51.61% [39.46; 63.58] in high TB burden countries and a prevalence of 40.24% [23.51; 59.61] in countries with low TB burden. In terms of development, in low- and lower-middle-income countries, the prevalence of active TB was 3.13% [1.84; 5.29] and in high- and upper-middle income countries the prevalence was 2.25% [1.70; 2.99]. The prevalence of latent TB in high- and middle-income countries was 43.77% [28.61; 60.18] and of 49.42% [45.91; 52.94] in low and lower middle-income countries.

CONCLUSION

Our analysis suggests that TB, and probably other infectious diseases, find fertile ground in prisons where previous acquire social disadvantages seem to thrive-therefore, TB in prisons is a global public health problem and effective strategies are needed to control the disease are needed targeting the prison environment, including rapid health assessments to understand each context and to implement tailored and precision interventions.

Yield and Coverage of Active Case Finding Interventions for Tuberculosis Control:A Systematic Review and Meta-analysis

Background

Active case finding (ACF) for tuberculosis (TB) is a key strategy to reduce diagnostic delays, expedite treatment, and prevent transmission.

Objective

Our objective was to identify the populations, settings, screening and diagnostic approaches that optimize coverage (proportion of those targeted who were screened) and yield (proportion of those screened who had active TB) in ACF programs.

Methods

We performed a comprehensive search to identify studies published from 1980-2016 that reported the coverage and yield of different ACF approaches. For each outcome, we conducted meta-analyses of single proportions to produce estimates across studies, followed by meta-regression to identify predictors. Findings. Of 3,972 publications identified, 224 met criteria after full-text review. Most individuals who were targeted successfully completed screening, for a pooled coverage estimate of 93.5%. The pooled yield of active TB across studies was 3.2%. Settings with the highest yield were internally-displaced persons camps (15.6%) and healthcare facilities (6.9%). When compared to symptom screening as the reference standard, studies that screened individuals regardless of symptoms using microscopy, culture, or GeneXpert®MTB/RIF (Xpert) had 3.7% higher case yield. In particular, microbiological screening (usually microscopy) as the initial test, followed by culture or Xpert for diagnosis had 3.6% higher yield than symptom screening followed by microscopy for diagnosis. In a model adjusted for use of Xpert testing, approaches targeting persons living with HIV (PLWH) had a 4.9% higher yield than those targeting the general population. In all models, studies targeting children had higher yield (4.8%-5.7%) than those targeting adults.

Conclusion

ACF activities can be implemented successfully in various populations and settings. Screening yield was highest in internally-displaced person and healthcare settings, and among PLWH and children. In high-prevalence settings, ACF approaches that screen individuals with laboratory tests regardless of symptoms have higher yield than approaches focused on symptomatic individuals.

Number needed to screen for TB in clinical, structural or occupational risk groups

BACKGROUND: Screening for active TB using active case-finding (ACF) may reduce TB incidence, prevalence, and mortality; however, yield of ACF interventions varies substantially across populations. We systematically reviewed studies reporting on ACF to calculate the number needed to screen (NNS) for groups at high risk for TB.METHODS: We conducted a literature search for studies reporting ACF for adults published between November 2010 and February 2020. We determined active TB prevalence detected through various screening strategies and calculated crude NNS for - TB confirmed using culture or Xpert® MTB/RIF, and weighted mean NNS stratified by screening strategy, risk group, and country-level TB incidence.RESULTS: We screened 27,223 abstracts; 90 studies were included (41 in low/moderate and 49 in medium/high TB incidence settings). High-risk groups included inpatients, outpatients, people living with diabetes (PLWD), migrants, prison inmates, persons experiencing homelessness (PEH), healthcare workers, and miners. Screening strategies included symptom-based screening, chest X-ray and Xpert testing. NNS varied widely across and within incidence settings based on risk groups and screening methods. Screening tools with higher sensitivity (e.g., Xpert, CXR) were associated with lower NNS estimates.CONCLUSIONS: NNS for ACF strategies varies substantially between adult risk groups. Specific interventions should be tailored based on local epidemiology and costs.

Molecular Epidemiology and Genetic Diversity of Multidrug-Resistant Mycobacterium tuberculosis Isolates in Bangladesh

Although the number of multidrug-resistant (MDR) tuberculosis (TB) cases is high overall, a major gap exists in our understanding of the molecular characteristics and transmission dynamics of the MDR Mycobacterium tuberculosis isolates circulating in Bangladesh. The present study aims to characterize the MDR-TB isolates of Bangladesh and to investigate the mode of transmission. A total of 544 MDR-TB isolates were obtained from a nationwide drug-resistant TB surveillance study conducted between October 2011 and March 2017 covering all geographic divisions of Bangladesh. The isolates were characterized using TbD1 deletion analysis, spoligotyping, and mycobacterial interspersed repetitive-unit–variable-number tandem-repeat (MIRU-VNTR) typing. Deletion analysis showed that 440 (80.9%) isolates were the modern type, while the remainder were the ancestral type. The largest circulating lineage was the Beijing type, comprising 208 isolates (38.2%), followed by T, EAI, and LAM with 93 (17.1%), 58 (10.7%), and 52 (9.5%) isolates, respectively. Combined MIRU-VNTR and spoligotyping analysis demonstrated that the majority of the clustered isolates were of the Beijing and T1 lineages. The overall rate of recent transmission was estimated at 33.8%. In conclusion, the MDR M. tuberculosis isolates circulating in Bangladesh are mostly of the modern virulent type. The Beijing and T lineages are the predominant types and most of the transmission of MDR-TB can be attributed to them. The findings also suggest that, along with the remarkable transmission, the emergence of MDR-TB in Bangladesh is largely due to acquired resistance. Rapid and accurate diagnosis and successful treatment will be crucial for controlling MDR-TB in Bangladesh.

IMPORTANCE Multidrug-resistant TB is considered to be the major threat to tuberculosis control activities worldwide, including in Bangladesh. Despite the fact that the number of MDR-TB cases is high, a major gap exists in our understanding of the molecular epidemiology of the MDR-TB isolates in Bangladesh. In our study, we characterized and classified the MDR-TB isolates circulating in Bangladesh and investigated their mode of transmission. Our results demonstrated that the MDR M. tuberculosis isolates circulating in Bangladesh are mostly of the modern virulent type. The Beijing and T lineages are the predominant types and are implicated in the majority of MDR-TB transmission. Our findings reveal that, along with the remarkable transmission, the emergence of MDR-TB in Bangladesh is largely due to acquired resistance, which may be due to nonadherence to treatment or inadequate treatment of TB patients. Rapid diagnosis and adherence to an appropriate treatment regimen are therefore crucial to controlling MDR-TB in Bangladesh.

Prevalence of multidrug-resistant tuberculosis in prisons: Systematic review and meta-analysis

BACKGROUND

In the context of prisons, multidrug-resistant tuberculosis (MDR-TB) is a major problem. In this article, we estimate the prevalence of MDR-TB among the population deprived of freedom from countries in South America, Europe, Asia and Africa.

METHODS

The articles were retrieved through systematic search at four databases (EMBASE, CINAHL, LILACS and MEDILINE). The meta-analysis was developed by the random effect model, using the Mantel-Haenszel method, with presentation of the aggregated results through the forest plot. The degree of heterogeneity between the studies was verified using Cochran's Q test and I².

RESULTS

Of the 102 articles analyzed, 21 were included in this systematic review. The analysis showed heterogeneity indicated by the Q test (P ​< ​0.001) and I² statistics (I² ​= ​50.52%). The funnel graph and Egger test (P ​< ​0.830) showed symmetry between investigations. The grouped prevalence of MDR-TB was 0.48% (95% CI: 0.02 to 1.32), advancing to 1.15 (95% CI: 0.15 to 2.73) when culture and sensitivity test were considered by the authors. No specific characteristics were significantly associated with differences in prevalence rates in the population deprived of freedom.

CONCLUSION

The study reaffirms the magnitude of MDR-TB in the population deprived of freedom in the world context. Political and technical-scientific efforts should be mobilized to mitigate TB and MDR-TB in prisons and for successful national and international disease control programs.

Genetic diversity and characterization of M. tuberculosis isolates causing extrapulmonary tuberculosis in Bangladesh

Tuberculosis (TB) remains one of the leading causes of death and Bangladesh ranks 7th among the highest TB burden countries. Though molecular epidemiological data for pulmonary TB (PTB) have previously been described in Bangladesh, data on the molecular characterization and clinical association with different lineages among extrapulmonary TB (EPTB) is lacking. The aim of the study was to investigate the molecular characterization and lineage distribution of M. tuberculosis isolates obtained from patients with EPTB in Bangladesh. Between November 2015 and March 2017, a total of 1,340 EPTB specimens including lymph node, pus, tissue, ascitic fluid, cerebrospinal fluid, pleural fluid, abscess wall, urine etc. were collected from four tertiary care hospitals in Dhaka city, Bangladesh. Among the specimens, 141 were found positive on solid culture. Molecular characterization of the 141 isolates was done by deletion analysis, spoligotyping and Mycobacterial Interspersed Repetitive Unit-Variable Number Tandem Repeats (MIRU-VNTR) analysis. Among the 141 isolates, 80 (56.7%) were found as 'modern' and the remaining 61 (43.3%) were 'ancestral' type. Spoligotyping results revealed 91 distinct patterns of which 74 isolates were unique and the remaining 67 were divided into 17 distinct clusters. East African- Indian (EAI) lineage was the most predominant, comprising 26 (18.4%) isolates, followed by the Beijing lineage (14.2%). 15-loci MIRU-VNTR analysis revealed that 132 isolates (93.5%) had unique patterns, whereas only 9 (6.5%) isolates were grouped into 4 distinct clusters. In conclusion, the study findings provide a first insight into genetic diversity of EPTB isolates in Bangladesh. The present study demonstrated that 'modern' strains were more prevalent among the EPTB cases, while EAI lineages were predominantly circulating in this region.

A systematic review of tuberculosis detection and prevention studies in prisons

Many studies have demonstrated that prisons are hotspots of tuberculosis disease and transmission. Despite this, it remains unclear which interventions are most effective at controlling tuberculosis in prisons. The objective was to determine the study designs used to investigate tuberculosis control in prisons, and the efficacy of interventions undertaken. This systematic review included published studies which had the aim of reducing TB incidence or prevalence, or increasing the number of people screened for active pulmonary tuberculosis in incarcerated populations. 2,429 records were identified, 178 full-text articles were screened, and 17 studies included. The majority of reports were before/after or prospective non-comparative studies. The median study duration was 23 months (range 5-144). The most common intervention was the introduction of active case finding (10/17 studies) but the timing and methods varied. Comparable pre- and post intervention outcome values were infrequently reported; therefore, it was not possible to quantify the efficacy of interventions. Data from studies of tuberculosis control in prisons is limited by a lack of: controlled interventions, reporting of pre-intervention methods, and comparable pre- and post-intervention outcomes. Prospective comparative trials of adequate duration to determine trends in incidence are necessary to understand which interventions are effective in prisons.

Treatment as prevention and other interventions to reduce transmission of multidrug-resistant tuberculosis

Drug-resistant tuberculosis (DR-TB) represents a major programmatic challenge at the national and global levels. Only ∼30% of patients with multidrug-resistant TB (MDR-TB) were diagnosed, and ∼25% were initiated on treatment for MDR-TB in 2016. Increasing evidence now points towards primary transmission of DR-TB, rather than inadequate treatment, as the main driver of the DR-TB epidemic. The cornerstone of DR-TB transmission prevention should be earlier diagnosis and prompt initiation of effective treatment for all patients with DR-TB. Despite the extensive scale-up of Xpert^® MTB/RIF testing, major implementation barriers continue to limit its impact. Although there is longstanding evidence in support of the rapid impact of treatment on patient infectiousness, delays in the initiation of effective DR-TB treatment persist, resulting in ongoing transmission. However, it is also imperative to address the burden of latent drug-resistant tuberculous infection because it is estimated that many DR-TB patients will become infectious before seeking care and encounter various diagnostic delays before treatment. Addressing latent DR-TB primarily consists of identifying, treating and following the contacts of patients with MDR-TB, typically through household contact evaluation. Adjunctive measures, such as improved ventilation and use of germicidal ultraviolet technology can further reduce TB transmission in high-risk congregate settings. Although many gaps remain in our biological understanding of TB transmission, implementation barriers to early diagnosis and rapid initiation of effective DR-TB treatment can and must be overcome if we are to impact DR-TB incidence in the short and long term.

Genotypic diversity of Mycobacterium tuberculosis isolates from North-Central Indian population

BACKGROUND

Different strains of Mycobacterium tuberculosis (MTB) are known to have different epidemiological and clinical characteristics. Some of them are widely distributed and associated with drug resistance, whereas others are locally predominated. Molecular epidemiological investigations have always been beneficial in identifying new strains and studying their transmission dynamics. Sahariya a primitive tribe of North Madhya Pradesh, India, has already been reported to have high prevalence of tuberculosis (TB) than their non-tribal neighbours. However, the information about MTB genotypes prevalent in Sahariya tribe and their non-tribal neighbours is not available.

METHODS

A total of 214 clinical isolates representing Sahariya tribe and non-tribes were analyzed by spoligotyping and MIRU-VNTR typing.

RESULTS

The EAI3_IND/SIT11 genotype was observed as major genotype in Sahariya tribe followed by CAS1_Delhi/SIT26 genotype. A 3.04 fold higher risk of getting TB with EAI3_IND/SIT11 genotype was observed in Sahariya as compared to the non-tribal population. The EAI_IND/SIT11 genotype also found to have more number of MDR-TB cases in Sahariya as well as true and possible transmission links. In Sahariya tribe, 3 clusters (6 isolates) reflected true transmission links, whereas 8 clusters consisted of 26 isolates revealed possible transmission links within the same geographical location or nearby houses.

CONCLUSION

The present study highlighted the predominance of EAI3_IND/SIT11 genotype in Sahariya tribe followed by CAS1_Delhi/SIT26 genotype. Combined approach of MIRU-VNTR typing and spoligotyping was observed more favourable in discrimination of MTB genotypes. Further, longitudinal studies using whole genome sequencing can provide more insights into genetic diversity, drug resistance and transmission dynamics of these prevalent genotypes.

Tuberculosis case detection by trained inmate peer educators in a resource-limited prison setting in Ethiopia: a cluster-randomised trial

BACKGROUND

To improve tuberculosis case detection, interventions that are feasible with available resources are needed. We investigated whether involving trained prison inmates in a tuberculosis control programme improved tuberculosis case detection, shortened pre-treatment symptom duration, and increased treatment success in a resource-limited prison setting in Ethiopia.

METHODS

In this cluster-randomised trial we randomly assigned prisons in the regions Amhara and Tigray of Ethiopia to an intervention group or a control group, after matching them into pairs based on their geographical proximity and size. Larger prisons were considered eligible whereas smaller prisons were excluded. We selected three to six prison inmates in each intervention prison. The recruited prison inmates who received a 3-day training course and were capable of identifying presumptive tuberculosis cases then provided health education to all other prison inmates about tuberculosis prevention and control every 2 weeks for 1 year. They also actively searched for symptomatic prison inmates and undertook routine symptom-based tuberculosis screening. The control prisons followed the existing passive case finding system. The primary outcome was the mean case detection rate at the end of the year, measured at cluster (prison) level. This trial is registered at ClinicalTrials.gov, number NCT02744521.

FINDINGS

We randomly assigned 16 prisons with a total population of 18 032 inmates to either the intervention group (n=8) or the control group (n=8) from April 1, 2016, to March 31, 2017. During the 1-year study period, 75 new tuberculosis cases (1% of 8874 total inmates) were detected in the intervention prisons and 25 new cases (<1% of 9158 total inmates) were detected in the control prisons. The mean case detection rate was significantly higher in the intervention group than in the control group (mean difference 52·9 percentage points, 95% CI 17·5-88·3, p=0·010).

INTERPRETATION

Involving trained inmate peer educators in the tuberculosis control programme in Ethiopian prisons significantly improved the tuberculosis case detection rate. The findings have important implications for clinical and public health policy, particularly in prisons of low-income countries where tuberculosis burden is high and the recommended tuberculosis diagnostic and treatment algorithms have generally not been implemented.

FUNDING

Nuffic, Mekelle University.

Molecular characterization and drug susceptibility profile of Mycobacterium tuberculosis isolates from Northeast Bangladesh

Tuberculosis (TB) remains a major public health problem worldwide including in Bangladesh. Molecular epidemiological tools provide genotyping profiles of Mycobacterium tuberculosis (M. tuberculosis) strains that can give insight into the transmission of TB in a specific region. The objective of the study was to identify the genetic diversity and drug susceptibility profile of M. tuberculosis strains circulating in the northeast Bangladesh. A total of 244 smear-positive sputum specimens were collected from two referral hospitals in Mymensingh and Netrakona districts. The isolated strains were genotyped by deletion analysis, spoligotyping, and MIRU-VNTR typing. We also analyzed the distributions of drug susceptibility pattern and demographic data among different genotypes. All isolates were identified as M. tuberculosis and among them 167 strains (68.44%) were 'ancestral' and the remaining 77 (31.56%) were 'modern' type. Spoligotyping analysis yielded 119 distinct patterns, among them, 86 isolates had unique patterns and the remaining 158 were grouped into 33 distinct clusters containing 2 to 18 isolates. The predominant spoligotypes belong to the EAI lineage strains, comprising 66 (27.04%) isolates followed by Beijing (7.38%), T1 (6.15%), CAS1-Delhi (5.33), LAM9 (3.28%), MANU-2 and X2. MIRU-VNTR analysis revealed 167 isolates (68%) had unique patterns, whereas 77 (32%) were grouped into 26 clusters and the rate of recent transmission was 20.9%, suggesting that the majority of TB cases in this region are caused by the reactivation of previous TB infections rather than recent transmission. About 136 (55.7%) isolates were sensitive to four anti-TB drugs, 69 (28.3%) were resistant to one or more (except rifampicin and isoniazid combination) drugs and 39 (15.9%) were MDR. In conclusion, our study provides a first insight into molecular characterization and drug resistance profile of M. tuberculosis strains in northeast Bangladesh which will ultimately contribute to the national TB control program.

Active Case Finding Among Homeless People as a Means of Reducing the Incidence of Pulmonary Tuberculosis in General Population

The incidence of tuberculosis (TB) declined more than two-fold, compared with the national average, in the northeastern region of Poland in the period of 2003-2012. During that time, four programs of active case finding of TB were conducted as part of which a total of 944 homeless individuals were examined and 21 cases of active TB were detected. The objective of the present study was to find out whether the observed beneficial epidemiological trend could be a result of those programs. We addressed the issue of how the active case finding programs in the homeless community affected the TB incidence in the general population using a modified crisscross SIS-type (Susceptible - Infected - Susceptible) model which describes the dynamics of TB spread between the homeless and non-homeless populations. The values calculated from our model proved highly congruent with the actual epidemiological data. Our analysis showed a significant decline in TB incidence within 1 year of completion of each active case finding program. The model shows that each identified and cured case in the homeless community reduced the number of new cases in the general population by 3-4 within 1 year and by up to 20 within 5 years.

Provider initiated tuberculosis case finding in outpatient departments of health care facilities in Ghana: yield by screening strategy and target group

Background

Meticulous identification and investigation of patients presenting with tuberculosis (TB) suggestive symptoms rarely happen in crowded outpatient departments (OPDs). Making health providers in OPDs diligently follow screening procedures may help increase TB case detection. From July 2010 to December 2013, two symptom based TB screening approaches of varying cough duration were used to screen and test for TB among general outpatients, PLHIV, diabetics and contacts in Accra, Ghana.

Methods

This study was a retrospective analysis comparing the yield of TB cases using two different screening approaches, allocated to selected public health facilities. In the first approach, the conventional 2 weeks cough duration with or without other TB suggestive symptoms was the criterion to test for TB in attendants of 7 general OPDs. In the second approach the screening criteria cough of >24 hours, as well as a history of at least one of the following symptoms: fever, weight loss and drenching night sweats were used to screen and test for TB among attendants of 3 general OPDs, 7 HIV clinics and 2 diabetes clinics. Contact investigation was initiated for index TB patients. The facilities documented the number of patients verbally screened, with presumptive TB, tested using smear microscopy and those diagnosed with TB in order to calculate the yield and number needed to screen (NNS) to find one TB case. Case notification trends in Accra were compared to those of a control area.

Results

In the approach using >24-hour cough, significantly more presumptive TB cases were identified among outpatients (0.82% versus 0.63%), more were tested (90.1% versus 86.7%), but less smear positive patients were identified among those tested (8.0% versus 9.4%). Overall, all forms of TB cases identified per 100,000 screened were significantly higher in the >24-hour cough approach at OPD (92.7 for cough >24 hour versus 82.7 for cough >2 weeks ), and even higher in diabetics (364), among contacts (693) and PLHIV (995). NNS (95% Confidence Interval) varied from 100 (93-109) for PLHIV, 144 (112-202) for contacts, 275 (197-451) for diabetics and 1144 (1101-1190) for OPD attendants. About 80% of the TB cases were detected in general OPDs. Despite the intervention, notifications trends were similar in the intervention and control areas.

Conclusion

The >24-hour cough approach yielded more TB cases though required TB testing for a larger number of patients. The yield of TB cases per 100,000 population screened was highest among PLHIV, contacts, and diabetics, but the majority of cases were detected in general OPDs. The intervention had no discernible impact on general case notification.

Prevalence of Smear-Positive Tuberculosis among Patients Who Visited Saint Paul's Specialized Hospital in Addis Ababa, Ethiopia

Background

Tuberculosis (TB) continues to be a health problem in both developed and developing countries, including Ethiopia.

Objective

In this study, the prevalence of smear-positive tuberculosis among presumptive TB cases who visited the hospital was assessed.

Method

Acid fast bacilli (AFB) test was performed on samples collected from 200 presumptive TB cases. Data were analyzed using appropriate statistical tools.

Result

Among 200 presumptive TB cases, 10% (20 individuals) (60% were male and 40% were female) were found to be positive for the AFB. Of these AFB positive subjects, 11.2% and 6.3% were from urban and rural areas, respectively. Among 20 AFB positive cases, 45% (9), 45% (9), and 10% (2) were HIV positive, HIV negative, and with HIV status unknown, respectively. The highest AFB positive cases were found within age group between 25 and 44 years (70%) and followed by age above 40 years (30%). It was found out that 75% (15), 15% (3), 5% (1), and 5% (1) were unemployed, government employed, student, and nongovernment employed, accordingly.

Conclusion

This study indicated higher level of AFB positive cases within age groups of 25–44 and 65–74 years and also exhibited higher prevalence of TB cases from urban areas.

Genetic Diversity of Mycobacterium tuberculosis Isolates from Assam, India: Dominance of Beijing Family and Discovery of Two New Clades Related to CAS1_Delhi and EAI Family Based on Spoligotyping and MIRU-VNTR Typing

Tuberculosis (TB) is one of the major public health concerns in Assam, a remote state located in the northeastern (NE) region of India. The present study was undertaken to explore the circulating genotypes of Mycobacterium tuberculosis complex (MTBC) in this region. A total of 189 MTBC strains were collected from smear positive pulmonary tuberculosis cases from different designated microscopy centres (DMC) from various localities of Assam. All MTBC isolates were cultured on Lowenstein-Jensen (LJ) media and subsequently genotyped using spoligotyping and 24-loci mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR) typing. Spoligotyping of MTBC isolates revealed 89 distinct spoligo patterns. The most dominant MTBC strain belonged to Beijing lineage and was represented by 35.45% (n = 67) of total isolates, followed by MTBC strains belonging to Central Asian-Delhi (CAS/Delhi) lineage and East African Indian (EAI5) lineage. In addition, in the present study 43 unknown spoligo patterns were detected. The discriminatory power of spoligotyping was found to be 0.8637 based on Hunter Gaston Discriminatory Index (HGDI). On the other hand, 24-loci MIRU-VNTR typing revealed that out of total 189 MTBC isolates from Assam 185 (97.9%) isolates had unique MIRU-VNTR profiles and 4 isolates grouped into 2 clusters. Phylogenetic analysis of 67 Beijing isolates based on 24-loci MIRU-VNTR typing revealed that Beijing isolates from Assam represent two major groups, each comprising of several subgroups. Neighbour-Joining (NJ) phylogenetic tree analysis based on combined spoligotyping and 24-loci MIRU-VNTR data of 78 Non-Beijing isolates was carried out for strain lineage identification as implemented by MIRU-VNTRplus database. The important lineages of MTBC identified were CAS/CAS1_Delhi (41.02%, n = 78) and East-African-Indian (EAI, 33.33%). Interestingly, phylogenetic analysis of orphan (23.28%) MTBC spoligotypes revealed that majority of these orphan isolates from Assam represent two new sub-clades Assam/EAI and Assam/CAS. The prevalence of multidrug resistance (MDR) in Beijing and Non-Beijing strains was found to be 10.44% and 9.01% respectively. In conclusion, the present study has shown the predominance of Beijing isolates in Assam which is a matter of great concern because Beijing strains are considered to be ecologically more fit enabling wider dissemination of M. tuberculosis. Other interesting finding of the present study is the discovery of two new clades of MTBC isolates circulating in Assam. More elaborate longitudinal studies are required to be undertaken in this region to understand the transmission dynamics of MTBC.