Seventy Years of Tuberculosis Prevention: Efficacy, Effectiveness, Toxicity, Durability, and Duration

Effectiveness of preventive treatment among different age groups and Mycobacterium tuberculosis infection status: a systematic review and individual-participant data meta-analysis of contact tracing studies

BACKGROUND

Tuberculosis is a preventable disease. However, there is debate regarding which individuals would benefit most from tuberculosis preventive treatment and whether these benefits vary in settings with a high burden and low burden of tuberculosis. We aimed to compare the effectiveness of tuberculosis preventive treatment in exposed individuals of differing ages and Mycobacterium tuberculosis infection status while considering tuberculosis burden of the settings.

METHODS

In this systematic review and individual-participant meta-analysis, we investigated the development of incident tuberculosis in people closely exposed to individuals with tuberculosis. We searched for studies published between Jan 1, 1998, and April 6, 2018, in MEDLINE, Web of Science, BIOSIS, and Embase. We restricted our search to cohort studies; case-control studies and outbreak reports were excluded. Two reviewers evaluated titles, abstracts, and full text articles for eligibility. At each stage, two reviewers discussed discrepancies and re-evaluated articles until a consensus was reached. Individual-participant data and a pre-specified list of variables, including characteristics of the exposed contact, the index patient, and environmental characteristics, were requested from authors of all eligible studies; contacts exposed to a drug-resistant tuberculosis index patient were excluded. The primary study outcome was incident tuberculosis. We estimated adjusted hazard ratios (aHRs) for incident tuberculosis with mixed-effects Cox regression models with a study-level random effect. We estimated the number-needed-to-treat (NNT) to prevent one person developing tuberculosis. Propensity score matching procedures were used in all analyses. This study is registered with PROSPERO (CRD42018087022).

FINDINGS

After screening 25 358 records for eligibility, 439 644 participants from 32 cohort studies were included in the individual-participant data meta-analysis. Participants were followed for 1 396 413 person-years (median of 2·7 years [IQR 1·3-4.4]), during which 2496 people were diagnosed with incident tuberculosis. Overall, effectiveness of preventive treatment was 49% (aHR 0·51 [95% CI 0·44-0·60]). Participants with a positive tuberculin-skin-test (TST) or IFNγ release assay (IGRA) result at baseline benefitted from greater protection, regardless of age (0·09 [0·05-0·17] in children younger than 5 years, 0·20 [0·15-0·28] in individuals aged 5-17 years, and 0·17 [0·13-0·22] in adults aged 18 years and older). The effectiveness of preventive treatment was greater in high-burden (0·31 [0·23-0·40]) versus low-burden (0·58 [0·47-0·72]) settings. The NNT ranged from 9 to 34 depending on age among participants with a positive TST or IGRA in both high-burden and low-burden settings; among all contacts (regardless of TST or IGRA test result), the NNT ranged from 29 to 43 in high-burden settings and 213 to 455 in low-burden settings.

INTERPRETATION

Our findings suggest that a risk-targeted strategy prioritising contacts with evidence of M tuberculosis infection might be indicated in low-burden settings, and a broad approach including all contacts should be considered in high-burden settings. Preventive treatment was similarly effective among contacts of all ages.

FUNDING

None.

Incidence of tuberculosis disease in individuals diagnosed with tuberculosis infection after screening: A population-based cohort study in South Korea

OBJECTIVES

Limited evidence exists regarding the impact of adherence to diverse tuberculosis (TB) preventive therapy (TPT) regimens on TB risk in individuals with TB infections (TBIs). This study aimed to examine the association between adherence to three TPT regimens and TB incidence.

METHODS

This population-based retrospective cohort study used South Korean national health insurance data to identify individuals who were newly diagnosed with TBI between 2015 and 2020. TB incidence was compared among the different TPT regimens used. Treatment adherence was evaluated using the medication possession ratio (MPR).

RESULTS

The study involved 220,483 individuals with TBI, with half undergoing TPT. Over a mean 3.17-year follow-up, 2,430 cases of active TB were observed. TPT was associated with a 14% reduction in TB incidence risk in the entire study population with varying levels of TB risk. Non-adherence (MPR <80%) rates were 36% for 9 months of treatment with isoniazid, 22% for 4 months of treatment with rifampicin, and 18% for 3 months of treatment with isoniazid and rifampicin. Non-adherence to TPT did not lead to a decrease in the risk of TB incidence, whereas adherence to TPT (MPR ≥80%) reduced the risk of TB incidence by up to 72%.

CONCLUSIONS

This study reveals increased adherence with shorter TPT regimens in a national TBI cohort, emphasizing the pivotal role of medication adherence in preventing TB.

US Guidelines Fall Short on Short-Course Tuberculosis-Preventive Therapy

The provision of tuberculosis-preventive therapy (TPT) to vulnerable populations is critical for global control. Shorter-course TPT regimens are highly effective and improve completion rates. Despite incorporation of 1 month of rifapentine and isoniazid into global guidelines, current US TPT guidelines do not include this as a recommended regimen, but should.

Oral and maxillofacial tuberculosis: A systematic review

OBJECTIVES

This study aimed to analyze the demographic, clinical, histopathological, diagnosis, treatment, and follow-up data on the occurrence of oral and maxillofacial tuberculosis (OMTB).

METHODS

Electronic searches without publication date restrictions were undertaken in four databases. Case reports and case series describing the occurrence of OMTB were included. Critical evaluation of studies was done using the Joanna Briggs Institute - University of Adelaide tool for case reports or case series.

RESULTS

A total of 217 studies were included in the qualitative synthesis, for a total of 301 cases of OMTB. Of these patients, 192 (63.7%) were male, with an average age of 39.6 ± 19.8 (15 months to 81 years). The tongue (n = 80/26.6%) represented the most common affected site, followed by the mandible (n = 43/14.3%). The clinical presentation consisted mainly of a painful ulcerated lesion (n = 156/56.5%). Histopathological analysis showed a granulomatous inflammation in most cases (n = 156/63.1%). The main diagnostic methods used were sputum test (n = 53/26.8%), culture (n = 49/24.7%) and purified protein derivative (PPD), or Mantoux test (n = 49/24.7%). Antituberculosis therapy was used in 244 cases (100.0%) and 5.2% of patients died.

CONCLUSIONS

This systematic review provided clinical, demographic data and information about diagnostic methods of OMTB lesions and served as an important guide to assist health professionals in the early diagnosis of these lesions.

Bacterial Lesions of the Oral Mucosa

Nonodontogenic bacterial infections of the oral cavity are not a common finding in the United States. Nevertheless, there has been an increase in prevalence of certain bacterial sexually transmitted diseases, such as syphilis and gonorrhea, and conditions such as tuberculosis still pose a serious threat to certain segments of the population. Finally, given the uncommon nature and pathophysiology of these diseases, diagnosis is often delayed, resulting in more clinically significant disease and potential contamination of individuals. Thus, it is prudent that clinicians be familiar with these uncommon but potentially serious infectious diseases, so treatment can be instituted promptly.

High Isoniazid Exposures When Administered with Rifapentine Once Weekly for Latent Tuberculosis in Individuals with Human Immunodeficiency Virus

Isoniazid pharmacokinetics are not yet well-described during once weekly, high-dose administrations with rifapentine (3HP) for latent tuberculosis infection (LTBI). Fewer data describe 3HP with dolutegravir-based antiretroviral therapy for the treatment of human immunodeficiency virus (HIV). The only prior report of 3HP with dolutegravir reported elevated isoniazid exposures. We measured the plasma isoniazid levels in 30 adults receiving 3HP and dolutegravir for the treatment of LTBI and HIV. The patients were genotyped to determine NAT2 acetylator status, and a population PK model was estimated by nonlinear mixed-effects modeling. The results were compared to previously reported data describing 3HP with dolutegravir, 3HP alone, and isoniazid with neither dolutegravir nor rifapentine. The isoniazid concentrations were adequately described by a one compartment model with a transit compartment absorption process. The isoniazid clearance for slow (8.33 L/h) and intermediate (12 L/h) acetylators were similar to previously reported values. Rapid acetylators (N = 4) had clearance similar to those of intermediate acetylators and much slower than typically reported, but the small sample size was limiting. The absorption rate was lower than usual, likely due to the coadministration with food, and it was faster among individuals with a low body weight. Low-body weight participants were also observed to have greater oral bioavailability. The isoniazid exposures were consistent with, or greater than, the previously reported "elevated" concentrations among individuals receiving 3HP and dolutegravir. The concentrations were substantially greater than those presented in previous reports among individuals receiving 3HP or isoniazid without rifapentine or dolutegravir. We discuss the implications of these findings and the possibility of a drug-drug interaction that is mediated by cellular transport. (This study has been registered at ClinicalTrials.gov under identifier NCT03435146 and has South African National Clinical Trial Registration no. DOH-27-1217-5770.).

Spinal Tuberculosis within the Vertebral Arch Mimicking a Malignant Tumor: Case Report

BACKGROUND

 Spinal tuberculosis is a manifestation of extrapulmonary tuberculosis. The incidence of tuberculosis is low in high-income countries; however, globally, it still remains one of the most frequent fatal infectious diseases. Because of its rarity in developed countries, spinal tuberculosis can be mistaken for malignant tumors of the spine, especially in case of an atypical radiologic manifestation and without pulmonary affection.

METHODS

 We present the case of a 39-year-old man from South India with quickly progressing gait disturbance and hypesthesia below the Th10 level. Magnetic resonance imaging revealed an osteolytic lesion of the vertebral arch Th2 with central necrosis and compression of the spinal cord altogether highly suspicious for spinal metastasis.

RESULTS

 After surgical removal of the mass by laminectomy, the patient regained normal neurologic function. Histology revealed a severe granulomatous inflammation and DNAhybridization of polymerase chain reaction (PCR) products detected Mycobacterium tuberculosis-specific DNA in the sample. Biopsy of an enlarged hilar lymphnode allowed us to obtain material to successfully perform a drug resistance test to start specific antimicrobial therapy.

CONCLUSION

 Spinal tuberculosis, even with atypical radiologic appearance, has to be considered a differential diagnosis in patients with provenance from endemic countries. A multidisciplinary diagnostic approach helps perform antimicrobial susceptibility testing to avoid delaying the start of antibiotic therapy.

Pharmacological Management of Pulmonary Tuberculosis: A Century of Expert Opinions in Cecil Textbook of Medicine

BACKGROUND

Advances in drug therapy for pulmonary tuberculosis have had an extraordinary impact on the incidence of tuberculosis in the United States in the past century, which has decreased from 113/100,000 persons in 1920 to 2.2/100,000 in 2020. Modern treatments have contributed to a remarkable decrease in hospitalizations and mortality and have had a significant impact on the duration and severity of illness, quality of life, and work potential of affected persons.

STUDY QUESTION

What are the milestones of the changes in the expert approach to the pharmacological management of pulmonary tuberculosis in the past century?

STUDY DESIGN

To determine the changes in the experts' approach to the management of pulmonary tuberculosis, as presented in a widely used textbook in the United States.

DATA SOURCES

The chapters describing the management of pulmonary tuberculosis in the 26 editions of Cecil Textbook of Medicine published from 1927 through 2020.

RESULTS

In the preantibiotic era (1927-1943), the Cecil authors emphasized rest, good food, and fresh air as the treatment pillars for pulmonary tuberculosis. The modern era (1947-1971) recorded the discovery of all the drugs that are still used for the initial treatment, in the following order: streptomycin, para-aminosalicylic acid, isoniazid, pyrazinamide, ethambutol, cycloserine, kanamycin, ethionamide, capreomycin, and rifampin. In the postmodern era (1975-2020), therapeutic advances continued with trials of many drug combinations aimed at ameliorating the duration of treatment, drug resistance adverse effects, and poor the recent addition of fluoroquinolones, bedaquiline, and clofazimine.

CONCLUSIONS

The pharmacological management of tuberculosis has remained archaic until the middle of the 20th century. Fundamental progress occurred in a very short period (1947-1971) and was because of the recognition of the antituberculous effect of many antibiotics and chemotherapy agents. The challenges created by mycobacterial infections resistant to multiple drugs remain and have prompted the addition of new drugs in the past decade.

"If I've got latent TB, I would like to get rid of it": Derivation of the CARD (Constraints, Actions, Risks, and Desires) Framework informed by South African healthcare worker perspectives on latent tuberculosis treatment

BACKGROUND

Healthcare workers (HWs) have at least twice the risk of tuberculosis (TB) compared to the general population. There is growing emphasis on latent TB infection (LTBI) in high-risk populations. Yet we know little about HWs' perspectives of LTBI testing and treatment to inform implementation in high-incidence settings. We developed a qualitative networked approach to analyze HWs' perspectives on LTBI testing and treatment.

METHODS

We conducted 22 in-depth interviews with nurse and physician stakeholders, who had been recruited as part of a larger study evaluating TB transmission risk in HWs at Tygerberg Hospital, Cape Town, South Africa. We performed open coding to identify emergent themes and selective coding to identify relevant text citations. We used thematic analysis to inductively derive the CARD (Constraints, Actions, Risks, Desires) framework.

RESULTS

All HWs desired to avoid developing TB but few felt this was actionable. Despite LTBI knowledge gaps, safety and cost concerns, most HWs reported hypothetical willingness to take LTBI treatment. The CARD framework showed that desire and action related to LTBI testing and treatment was clearly framed by the interactions between constraints, administrative action, and risk. The surprise HWs described on receiving a negative LTBI (Quantiferon-Plus) result suggests LTBI testing may recalibrate HWs' perceptions regarding the futility of actions to reduce their TB risk.

CONCLUSIONS

LTBI testing and treatment are acceptable to HWs and could counteract the perceived inevitability of occupational TB infection that currently may limit risk reduction action. This should be coupled with administrative leadership and infrastructural support. The CARD analytic framework is a helpful tool for implementation scientists to understand current practices within complex health systems. Application of CARD could facilitate the development of contextually-relevant interventions to address important public health problems such as occupational TB.

A Randomized Controlled Trial of Isoniazid to Prevent Mycobacterium tuberculosis Infection in Kenyan Human Immunodeficiency Virus-Exposed Uninfected Infants

BACKGROUND

Human immunodeficiency virus (HIV)-exposed uninfected (HEU) infants in endemic settings are at high risk of tuberculosis (TB). For infants, progression from primary Mycobacterium tuberculosis (Mtb) infection to TB disease can be rapid. We assessed whether isoniazid (INH) prevents primary Mtb infection.

METHODS

We conducted a randomized nonblinded controlled trial enrolling HEU infants 6 weeks of age without known TB exposure in Kenya. Participants were randomized (1:1) to 12 months of daily INH (10 mg/kg) vs no INH. Primary endpoint was Mtb infection at end of 12 months, assessed by interferon-γ release assay (QuantiFERON-TB Gold Plus) and/or tuberculin skin test (TST, added 6 months after first participant exit).

RESULTS

Between 15 August 2016 and 6 June 2018, 416 infants were screened, with 300 (72%) randomized to INH or no INH (150 per arm); 2 were excluded due to HIV infection. Among 298 randomized HEU infants, 12-month retention was 96.3% (287/298), and 88.9% (265/298) had primary outcome data. Mtb infection prevalence at 12-month follow-up was 10.6% (28/265); 7.6% (10/132) in the INH arm and 13.5% (18/133) in the no INH arm (7.0 vs 13.4 per 100 person-years; hazard ratio, 0.53 [95% confidence interval {CI}, .24-1.14]; P = .11]), and driven primarily by TST positivity (8.6% [8/93] in INH and 18.1% [17/94] in no INH; relative risk, 0.48 [95% CI, .22-1.05]; P = .07). Frequency of severe adverse events was similar between arms (INH, 14.0% [21/150] vs no INH, 10.7% [16/150]; P = .38), with no INH-related adverse events.

CONCLUSIONS

Further studies evaluating TB preventive therapy to prevent or delay primary Mtb infection in HEU and other high-risk infants are warranted.

CLINICAL TRIALS REGISTRATION

NCT02613169.

Vaccination with Alpha-Gal Protects Against Mycobacterial Infection in the Zebrafish Model of Tuberculosis

The alpha-Gal syndrome (AGS) is associated with tick bites that can induce in humans high levels of IgE antibodies against the carbohydrate Galα1-3Galβ1-(3)4GlcNAc-R (α-Gal) present in glycoproteins and glycolipids from tick saliva that mediate primarily delayed anaphylaxis to mammalian meat consumption. It has been proposed that humans evolved by losing the capacity to synthesize α-Gal to increase the protective immune response against pathogens with this modification on their surface. This evolutionary adaptation suggested the possibility of developing vaccines and other interventions to induce the anti-α-Gal IgM/IgG protective response against pathogen infection and multiplication. However, the protective effect of the anti-α-Gal immune response for the control of tuberculosis caused by Mycobacterium spp. has not been explored. To address the possibility of using vaccination with α-Gal for the control of tuberculosis, in this study, we used the zebrafish-Mycobacterium marinum model. The results showed that vaccination with α-Gal protected against mycobacteriosis in the zebrafish model of tuberculosis and provided evidence on the protective mechanisms in response to vaccination with α-Gal. These mechanisms included B-cell maturation, antibody-mediated opsonization of mycobacteria, Fc-receptor (FcR)-mediated phagocytosis, macrophage response, interference with the α-Gal antagonistic effect of the toll-like receptor 2 (TLR2)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB)-mediated immune response, and upregulation of pro-inflammatory cytokines. These results provided additional evidence supporting the role of the α-Gal-induced immune response in the control of infections caused by pathogens with this modification on their surface and the possibility of using this approach for the control of multiple infectious diseases.

Historical review of studies on the effect of treating latent tuberculosis

Tuberculosis Preventive Therapy (TPT) is widely used in particular among high-risk populations such as close contacts and immunosuppressed people mostly in high-income settings. TPT is widely recommended for high-risk populations including HIV-infected and household contacts globally, but is not widely used. Historical trials on risk groups as well as the general population have documented a marked effect on reductions in incidence of active disease among those treated, as well as on prevalence of latent TB infection (LTBI) in populations where massive roll-out of TPT has previously taken place. This review summarizes the results of large historical trials conducted more than 50 years ago among Inuit and African populations as well as risk groups in the USA and Europe exhibiting similarities with current high-burden populations with current limited use of TPT. The trials demonstrated a 27-95% reduction in incidence of active TB among those receiving preventive treatment compared with placebo, with efficacy depending somewhat on length of treatment but mostly on adherence rates. It was possible to achieve satisfactory adherence rates in most of the trial populations and liver toxicity rates were generally low. The historical trials on preventive treatment for LTBI have documented that large-scale TPT is possible and effective even in high-burden populations in high-incidence areas and is therefore a relevant tool to consider in striving to eliminate the TB epidemic.