Relative Versus Absolute Noncontagiousness of Respiratory Tuberculosis on Treatment

Dynamics of sputum conversion during effective tuberculosis treatment: A systematic review and meta-analysis

BACKGROUND

Two weeks' isolation is widely recommended for people commencing treatment for pulmonary tuberculosis (TB). The evidence that this corresponds to clearance of potentially infectious tuberculous mycobacteria in sputum is not well established. This World Health Organization-commissioned review investigated sputum sterilisation dynamics during TB treatment.

METHODS AND FINDINGS

For the main analysis, 2 systematic literature searches of OvidSP MEDLINE, Embase, and Global Health, and EBSCO CINAHL Plus were conducted to identify studies with data on TB infectiousness (all studies to search date, 1 December 2017) and all randomised controlled trials (RCTs) for drug-susceptible TB (from 1 January 1990 to search date, 20 February 2018). Included articles reported on patients receiving effective treatment for culture-confirmed drug-susceptible pulmonary TB. The outcome of interest was sputum bacteriological conversion: the proportion of patients having converted by a defined time point or a summary measure of time to conversion, assessed by smear or culture. Any study design with 10 or more particpants was considered. Record sifting and data extraction were performed in duplicate. Random effects meta-analyses were performed. A narrative summary additionally describes the results of a systematic search for data evaluating infectiousness from humans to experimental animals (PubMed, all studies to 27 March 2018). Other evidence on duration of infectiousness-including studies reporting on cough dynamics, human tuberculin skin test conversion, or early bactericidal activity of TB treatments-was outside the scope of this review. The literature search was repeated on 22 November 2020, at the request of the editors, to identify studies published after the previous censor date. Four small studies reporting 3 different outcome measures were identified, which included no data that would alter the findings of the review; they are not included in the meta-analyses. Of 5,290 identified records, 44 were included. Twenty-seven (61%) were RCTs and 17 (39%) were cohort studies. Thirteen studies (30%) reported data from Africa, 12 (27%) from Asia, 6 (14%) from South America, 5 (11%) from North America, and 4 (9%) from Europe. Four studies reported data from multiple continents. Summary estimates suggested smear conversion in 9% of patients at 2 weeks (95% CI 3%-24%, 1 single study [N = 1]), and 82% of patients at 2 months of treatment (95% CI 78%-86%, N = 10). Among baseline smear-positive patients, solid culture conversion occurred by 2 weeks in 5% (95% CI 0%-14%, N = 2), increasing to 88% at 2 months (95% CI 84%-92%, N = 20). At equivalent time points, liquid culture conversion was achieved in 3% (95% CI 1%-16%, N = 1) and 59% (95% CI 47%-70%, N = 8). Significant heterogeneity was observed. Further interrogation of the data to explain this heterogeneity was limited by the lack of disaggregation of results, including by factors such as HIV status, baseline smear status, and the presence or absence of lung cavitation.

CONCLUSIONS

This systematic review found that most patients remained culture positive at 2 weeks of TB treatment, challenging the view that individuals are not infectious after this interval. Culture positivity is, however, only 1 component of infectiousness, with reduced cough frequency and aerosol generation after TB treatment initiation likely to also be important. Studies that integrate our findings with data on cough dynamics could provide a more complete perspective on potential transmission of Mycobacterium tuberculosis by individuals on treatment.

TRIAL REGISTRATION

Systematic review registration: PROSPERO 85226.

Initial loss to follow up of tuberculosis patients in South Africa: perspectives of program managers

Background

Tuberculosis (TB) remains a serious public health problem in South Africa. Initial loss to follow up (LTFU) rates among TB patients are high, varying between 14.9 and 22.5%. From the perspective of patients, documented reasons for this include poor communication between patient and staff after testing, not being aware that results are ready and other competing priorities such as preference to go to work as opposed to seeking healthcare. Ward-based Outreach Teams (WBOTs) routinely conduct home visits to ensure adherence to medication for various conditions including TB. We explored reasons for TB initial loss to follow up from the perspectives of TB program managers and WBOT program managers, with a focus on the WBOT’s (potential) role in reducing initial LTFU, in particular.

Methods

Key informant interviews with five WBOT program managers and four TB program managers were conducted. The interviews were audio-recorded, then transcribed and exported to NVivo 11 software for coding. A hybrid analytic approach consisting of both inductive and deductive coding was used to identify themes.

Results

The age of the nine managers ranged between 28 and 52 years old, of which two were male. They had been in their current position for between 2 to 12 years. Prior to treatment initiation, WBOTs screen household members for TB and refer them for TB testing if need be, but integration of the two programs is emphasized only after TB treatment has been initiated. Counseling of patients testing for TB is not guaranteed due to frequent staff rotations and staff shortages. Participants reported that possible dissatisfaction with services as well as stigma associated with the TB diagnosis could explain loss to follow up prior to treatment initiation.

Conclusion

Program managers view health system related factors such as staff rotations, poor communication with patients and lack of counseling as contributing to the problem of initial LTFU among TB patients. The integration of the WBOT and TB programs is limited to referring suspected cases for testing and patients already on treatment.

Initial loss to follow up among tuberculosis patients: the role of Ward-Based Outreach Teams and short message service (SMS) technology (research proposal)

Introduction

Tuberculosis (TB) is a problem in South Africa. Initial loss to follow up (LTFU) among TB patients is high varying between 14.9 and 18%. Some of the reasons for this are: lack of proper communication between patient and staff on next steps after testing, not aware that results are ready; and other competing priorities. Receiving reminder messages that result is ready is an intervention that can be explored to reduce initial LTFU. This can be through either receiving a note from the Ward-Based Outreach Teams (WBOTs) or via short message service (SMS) advising the patient to collect test result at the facility. This proposal aims to assess the effectiveness of WBOTs or SMS technology in reducing TB initial LTFU.

Methods

This will be a mixed methods approach. In depth interviews with WBOT Managers and TB Program Managers will be conducted. Focus group discussions with WBOT members will also be conducted. Two interventions (enhanced WBOTs/SMS technology) will be tested using a 3 arm randomized controlled trial (standard of care, SMS technology or enhanced WBOTs). The WBOTs will deliver paper note reminders while SMS intervention will entail sending reminder SMS messages to patients as soon as TB results are ready.

An Evaluation of Treatment Outcomes in a Cohort of Clients on the DOTS Strategy, 2012-2016

We present, for the first time, an evaluation of treatment outcomes in a cohort at a TB referral centre in the Central Region of Ghana. Of the 213 clients placed on DOTS, 59.2% (126/213) were sputum smear-positive. An overall cure rate of 90.2% (51.6% cured + 37.6% completed) and a death rate of 8.5% (18/213) were estimated. Of the number of clients who died, 5.7% (12/213) were males (χ² = 2.891, p = 0.699; LR = 3.004, p = 0.699). Deaths were only recorded among clients who were > 19 years old (χ² = 40.319, p = 0.099; LR = 41.244, p = 0.083). Also, 0.9% (2/213) was lost to follow-up, while 1.4% (3/213) had treatment failure. In total, 13.6% (7.0%, 15/213 males, and 6.6%, 14/213 females) of clients who were placed on DOTS were HIV seropositive. Ages of 40–49 years had the highest number, 13/213 (6.1%), infected with HIV, though the difference among the remaining age groups was not statistically significant (χ² = 9.621, p = 0.142). Furthermore, 7.0% (15/213) had TB/HIV coinfection. Out of them, 9 were cured and 5 died at home, while 1 had treatment failure. Tuberculosis/HIV infection prevention advocacy and interventions that address sociodemographic determinants of unfavourable treatment outcomes are urgently required to augment national efforts towards control.

Role of Anaemia and Magnesium Levels at the Initiation of Tuberculosis Therapy with Sputum Conversion among Pulmonary Tuberculosis Patients

INTRODUCTION

Both pulmonary Tuberculosis (TB) and anaemia are prevalent in India. Magnesium levels also influence TB. There is limited and inconsistent literature on the association among anaemia, serum magnesium levels and sputum conversion during tuberculosis treatment.

AIM

To study the effect of anaemia and serum magnesium levels on sputum conversion in pulmonary TB patients.

MATERIALS AND METHODS

One hundred each of newly diagnosed sputum smear positive Pulmonary Tuberculosis (PTB), sputum smear negative PTB patients initiated on Directly Observed Treatment Short Course chemotherapy (DOTS) and healthy age and sex matched controls were recruited in the study. Patients were followed up prospectively until completion of first two months of intensive phase. Patients were evaluated before initiation of TB treatment by performing the complete blood counts with peripheral blood smear, serum biochemistry, serum iron, serum magnesium, serum ferritin and microscopic examination of sputum. After giving two months of Antitubercular Therapy (ATT), sputum smears were re-examined for presence of acid fast bacilli. Haemoglobin values less than 13 g/dl in males or 12 g/dl in females was defined as anaemia. Mean and Standard deviations were calculated. Independent t-test was used to compare between the groups.

RESULTS

Serum iron and serum ferritin was significantly lower in sputum positive PTB as compared to sputum negative PTB and controls. Anaemia was present in 162 (81%) patients of the study PTB cases. About 60% of anaemia in sputum positive cases was iron deficiency anaemia. Serum magnesium level was significantly lower in sputum positive PTB as compared to sputum negative PTB and controls though not in hypomagnesemic range. Delayed sputum smear conversion occurred in 12 (12%) sputum positive PTB patients. Of these, eight had severe iron deficiency anaemia, four with moderate anaemia. All 12 delayed sputum smear conversion had serum magnesium levels < 1.7 mg/dl (below normal reference range) (mean 1.42 ±0.22 mg/dl).

CONCLUSION

Sputum was found to be positive even after two months of ATT course because of baseline anaemia and lower levels of serum magnesium. Further multicentric studies are warranted to study mechanisms for TB associated anaemia and possible role of intervention for anaemia in TB patients. One needs to find out the mechanisms behind the role of anaemia and lower magnesium levels in delaying the sputum smear conversion in order to lay the foundation of effective interventions. Randomized controlled trials are warranted to generate higher levels of evidences to support our findings.

Microbiologically Confirmed Tuberculosis: Factors Associated with Pre-Treatment Loss to Follow-Up, and Time to Treatment Initiation

Background

The impact of new diagnostics on pre-treatment loss to follow up (Pre-treatment LTFU) has not been widely investigated. The reported rate of pre-treatment LTFU is however lower in studies where Xpert MTB/Rif (Xpert) has been used onsite as opposed to centrally. The use of the Xpert at point of care (POC) could have a role in reducing the pre-treatment LTFU rate among TB patients. We aimed to determine the pre-treatment LTFU rate and the time to treatment initiation as well as to describe associated factors in patients diagnosed with TB using POC Xpert or smear microscopy.

Method

Xpert machines were installed at 7 primary healthcare facilities in inner-city Johannesburg. POC Xpert TB testing was the primary diagnostic method for all patients although there were some patients who were tested using only laboratory-based smear microscopy (during power outages or machine operator off-sick). Data on patients’ demographics, TB diagnostic test (Xpert or smear microscopy), test result, and time to treatment initiation were collected. Associations and predictors of pre-treatment LTFU and time to treatment initiation were explored.

Findings

A total of 1981 people with presumptive TB were tested (1743 using Xpert and 238 using smear). A bacteriological diagnosis of TB was made in 271 patients (90% Xpert; 10% smear). The median time to treatment initiation in the smear group was 9 days (IQR: 4–20) while those tested using Xpert had a median time of 0 days (IQR: 0–0). Pre-treatment LTFU was 22.5% with no difference between diagnostic groups (p = 0.8).

Conclusion

The Pre-treatment LTFU rate of 22.5% found in this study is much higher than the 5% target of the South African National TB Control Program. POC Xpert resulted in a significantly greater proportion of bacteriologically proven TB patients being started on treatment within 30 days of presentation. No risk factors associated with pre-treatment LTFU were identified.

Association between Body Mass Index and Sputum Culture Conversion among South Korean Patients with Multidrug Resistant Tuberculosis in a Tuberculosis Referral Hospital

Background

Multidrug-resistant tuberculosis (MDR-TB) is an important global health problem. Furthermore, the time to identify a positive sputum culture is an important risk factor for the spread of tuberculosis, and several factors can predict a prolonged time to culture conversion. Moreover, the relationship between poor nutritional status and infectious disease is clearly established. Therefore, the present study aimed to investigate the association between body mass index (BMI) and sputum culture conversion within 3 months among patients with MDR-TB.

Materials and Methods

We retrospectively evaluated 218 patients with MDR-TB who were treated at a large tuberculosis referral hospital in South Korea between January 2005 and December 2010. The outcome of interest was defined as sputum culture conversion within 3 months, and we analyzed the association between BMI and this outcome.

Results

Among the 218 patients, 53 patients (24.3%) had a low BMI (<18.5 kg/m²). In the multivariate Cox proportional-hazards regression analysis, failure to achieve sputum culture conversion within 3 months was independently associated with having a low BMI (hazard ratio [HR]: 1.741, 95% confidence interval [CI]: 1.006–3.013; P = 0.047) and a positive sputum smear at the initiation of therapy (HR: 8.440, 95% CI: 1.146–62.138, P = 0.036).

Conclusion

Low BMI (<18.5 kg/m²) was an independent risk factor for failure to achieve sputum culture conversion within 3 months among patients with MDR-TB.

Official American Thoracic Society/Centers for Disease Control and Prevention/Infectious Diseases Society of America Clinical Practice Guidelines: Treatment of Drug-Susceptible Tuberculosis

The American Thoracic Society, Centers for Disease Control and Prevention, and Infectious Diseases Society of America jointly sponsored the development of this guideline for the treatment of drug-susceptible tuberculosis, which is also endorsed by the European Respiratory Society and the US National Tuberculosis Controllers Association. Representatives from the American Academy of Pediatrics, the Canadian Thoracic Society, the International Union Against Tuberculosis and Lung Disease, and the World Health Organization also participated in the development of the guideline. This guideline provides recommendations on the clinical and public health management of tuberculosis in children and adults in settings in which mycobacterial cultures, molecular and phenotypic drug susceptibility tests, and radiographic studies, among other diagnostic tools, are available on a routine basis. For all recommendations, literature reviews were performed, followed by discussion by an expert committee according to the Grading of Recommendations, Assessment, Development and Evaluation methodology. Given the public health implications of prompt diagnosis and effective management of tuberculosis, empiric multidrug treatment is initiated in almost all situations in which active tuberculosis is suspected. Additional characteristics such as presence of comorbidities, severity of disease, and response to treatment influence management decisions. Specific recommendations on the use of case management strategies (including directly observed therapy), regimen and dosing selection in adults and children (daily vs intermittent), treatment of tuberculosis in the presence of HIV infection (duration of tuberculosis treatment and timing of initiation of antiretroviral therapy), as well as treatment of extrapulmonary disease (central nervous system, pericardial among other sites) are provided. The development of more potent and better-tolerated drug regimens, optimization of drug exposure for the component drugs, optimal management of tuberculosis in special populations, identification of accurate biomarkers of treatment effect, and the assessment of new strategies for implementing regimens in the field remain key priority areas for research. See the full-text online version of the document for detailed discussion of the management of tuberculosis and recommendations for practice.

Indications to Hospital Admission and Isolation of Children With Possible or Defined Tuberculosis: Systematic Review and Proposed Recommendations for Pediatric Patients Living in Developed Countries. [Corrected]

Tuberculosis (TB) is a re-emerging health problem in developed countries. This paper is part of large guidelines on the global management of TB in children, by a group of scientific societies. It describes the indications to hospitalization of children with suspected or diagnosed TB, the isolation measures, hospital discharge, and re-admission into the community. Using the Consensus Conference method, relevant publications in English were identified by means of a systematic review of MEDLINE and the Cochrane Database of Systematic Reviews from their inception until 31 December 2014. Available data on indications to hospitalization were mainly indirect and largely derived from observational studies. They include: (1) host-related risk factors, the main being age <12 months, immune deficiencies, and malnutrition; (2) TB-related clinical conditions that resemble those of pneumonia but also include drug-resistance; and (3) social and logistic conditions. The latter are based on opinion and depend on local conditions. Analysis of the literature showed that patients hospitalized with suspected pulmonary TB should be put in precautionary respiratory isolation regardless of their age while they await diagnosis. The general conditions for re-admission into the community are at least 14 days of effective treatment and negative microscopic tests of 3 consecutive samples in previously microscopically positive patients. This is the first paper that provides indications to hospitalization of children with TB. Most recommendations are generally applicable in all developed countries. Some might need an adaptation to local setting, epidemiological, parameters, and availability of specific health-care facilities.

Anemia at the initiation of tuberculosis therapy is associated with delayed sputum conversion among pulmonary tuberculosis patients in Dar-es-Salaam, Tanzania

Background

Pulmonary tuberculosis and anemia are both prevalent in Tanzania. There is limited and inconsistent literature on the association between anemia and sputum conversion following tuberculosis treatment.

Methods

Newly diagnosed sputum smear positive pulmonary tuberculosis patients aged ≥15 years initiating on standard anti tuberculosis therapy were recruited from 14 of 54 tuberculosis clinics in Dar es Salaam. Patients were receiving medication according to the recommended short course Directly Observed Therapy (DOT) strategy and were followed up prospectively until completion of treatment (six months). Patients were evaluated before initiation of TB treatment by performing the following; clinical history, physical examination, complete blood counts, serum biochemistry and sputum microscopy. Sputum smears were re-examined at two months of anti-tuberculosis therapy for presence of acid fast bacilli. Anemia was defined as hemoglobin <13 g/dl (males) or <12 g/dl (females). Log-binomial regression was used to assess the association between anemia and sputum conversion at two months.

Results

Of the 1245 patients included in the study, 86% were anemic and 7% were sputum smear positive at two months of anti-tuberculosis therapy. Anemic patients were three times more likely to have sputum positive smear as compared to non-anemic patients at two months (RR = 3.05; 95% CI 1.11–8.40) p = 0.03. The risk for sputum positive smear results increased with severity of anemia (P for trend <0.01).

Conclusion

Baseline anemia is associated with increased risk for persistent positive sputum smears at two months of tuberculosis treatment. Future studies should evaluate the mechanisms for TB-associated anemia as well as the role of intervention for anemia among TB patients.

Factors Influencing Sputum Conversion among Smear-Positive Pulmonary Tuberculosis Patients in Morocco

Background. Sputum smear-positive pulmonary tuberculosis patients expel infectious viable bacilli for a period following the commencement of treatment. Objective. To determine the time to sputum smear conversion and study the factors influencing it. Design. A prospective study was undertaken at our hospital in Rabat over a six-month period on a cohort of 119 sputum smear positive patients. Patients were followed up fortnightly. At each followup, specimens were collected and processed for microscopy using standard protocol. Results. 96.6% of our patients completed the study (4 deaths). Sputum conversion rate was 42% after two weeks, 73% after one month, and 95% after two months. Univariate and stepwise regression analysis showed that patients who had high smear grading, miliary, and bilateral radiologic lesions were more likely to undergo delayed sputum conversion (P<0.05). Other factors were thought to influence sputum conversion but were not statistically proven in our study. Conclusion. Since viable bacilli continue to be expelled for up to two months, infection control measures should be maintained for such a time. Patients with high smear grading, miliary, and bilateral radiologic lesions need to be monitored more closely.

Rapid DNA extraction for specific detection and quantitation of Mycobacterium tuberculosis DNA in sputum specimens using Taqman assays

Rapid tuberculosis (TB) detection is critical for disease control, and further quantitation of Mycobacterium tuberculosis (Mtb) in sputum is valuable for epidemiological and clinical studies. We evaluated a simple, robust and cost-efficient in-house DNA extraction and downstream Taqman approach for detection and quantitation of Mtb genomes from sputum of newly-diagnosed TB patients and non-TB controls. DNA was extracted using guanidine isothiocyanate and silica-based spin columns in less than 2 h, stored frozen, and Taqman assays were used to detect Mtb with IS6110 and quantify it targeting RD1 and IS1081. The Taqmans had a sensitivity >95% in 108 culture-confirmed TB patients and specificity of 100% in 43 non-TB controls. Genome counts were correlated with the Mycobacterial Growth Indicator Tubes' (MGIT) time-to-detection values (1/TTD × 1000; rho = 0.66; p < 0.001) in 91 TB patients (33 excluded with MGIT contamination). This linear relationship was nearly identical between mycobacteria isolated from sputum and H37Rv Mtb grown in-vitro to its log phase. TB treatment between 3 and 7 days was associated with lower 1/TTD × 1000 values but not with genome counts. Together, our protocol provides rapid, specific, inexpensive and quantitative detection of Mtb DNA in fresh or stored sputa making it a robust tool for prompt TB diagnosis, and with potential use for clinical and epidemiologic studies.

Prolonged infectiousness of tuberculosis patients in a directly observed therapy short-course program with standardized therapy

BACKGROUND

Effective tuberculosis control is compromised by a lack of clarity about the timeframe of viable Mycobacterium tuberculosis shedding after treatment initiation under programmatic conditions. This study quantifies time to conversion from smear and culture positivity to negativity in unselected tuberculosis patients receiving standardized therapy in a directly observed therapy short-course (DOTS) program.

METHODS

Longitudinal cohort study following up 93 adults initiating tuberculosis therapy in Lima, Peru. Baseline culture and drug susceptibility tests (DSTs) were performed using the MBBacT, proportion, and microscopic observation drug susceptibility (MODS) methods. Smear microscopy and MODS liquid culture were performed at baseline and weekly for 4 weeks then every other week for 26 weeks.

RESULTS

Median conversion time from culture positivity to culture negativity of 38.5 days was unaffected by baseline smear status. Patients with fully susceptible tuberculosis had a median time to culture conversion of 37 days; 10% remained culture positive at day 60. Delayed culture conversion was associated with multidrug resistance, regardless of DST method used; non-multidrug resistance as defined by the proportion method and MODS (but not MBBacT) was also associated with delay. Persistent day 60 smear positivity yielded positive and negative predictive values of 67% and 92%, respectively, for detecting multidrug resistance.

CONCLUSIONS

Smear and culture conversion in treated tuberculosis patients takes longer than is conventionally believed, even with fully susceptible disease, and must be accounted for in tuberculosis treatment and prevention programs. Persistent day 60 smear positivity is a poor predictor of multidrug resistance. The industrialized-world convention of universal baseline DST for tuberculosis patients should become the standard of care in multidrug resistance-affected resource-limited settings.

Inhaled nitric oxide treatment of patients with pulmonary tuberculosis evidenced by positive sputum smears

Endogenous nitric oxide (NO) has antimycobacterial properties. We tested the hypothesis that exogenous (inhaled) NO can be safely delivered and can accelerate airway disinfection for pulmonary tuberculosis patients treated with standard therapy. Exogenous NO administered at 80 ppm for 72 h can be safely delivered but does not accelerate airway disinfection.

Pediatric tuberculosis in Alberta First Nations (1991-2000): outbreaks and the protective effect of bacille Calmette-Guérin (BCG) vaccine

BACKGROUND

The tuberculosis control strategy of vaccinating First Nations newborns with BCG (bacille Calmette-Guerin) is currently undergoing re-evaluation in Canada. Review of recent pediatric tuberculosis morbidity could inform this re-evaluation.

METHODS

Potential source cases and pediatric cases of tuberculosis from Alberta First Nations were identified over the 10 years 1991-2000. The distribution of pediatric disease was described. The effect of BCG on tuberculosis morbidity in two large outbreaks was determined.

RESULTS

A total of 57 potential source cases and 41 pediatric cases of tuberculosis were reported from 17 (41.5%) and 8 (19.5%) of the 41 on-reserve First Nation Community Health Centres, respectively. Three outbreaks traceable to three source cases accounted for 34 (18, 3, and 13, respectively) of the 41 (82.9%) pediatric cases. Each outbreak was spatially and temporally separate from the other. Each outbreak strain of Mycobacterium tuberculosis had a unique DNA fingerprint. In the largest outbreaks, disease-to-infection ratios (secondary case rates) were higher in newly infected unvaccinated versus vaccinated close pediatric contacts (12/13 [92.3%] versus 7/15 [46.7%], p=0.02), but the infection rate was almost certainly falsely high in the BCG vaccinated. One unvaccinated child had a brain tuberculoma in addition to primary pulmonary tuberculosis.

CONCLUSION

For most Alberta First Nations communities, the spatial and temporal distribution of disease, and the meager impact on morbidity, challenge the rationale for continued use of BCG.