Infant TB Infection Prevention Study (iTIPS): a randomised trial protocol evaluating isoniazid to prevent M. tuberculosis infection in HIV-exposed uninfected children

Clinical efficacy of dexamethasone combined with isoniazid in the treatment of tuberculous meningitis and its effect on peripheral blood T cell subsets

Objective

To investigate the clinical efficacy of dexamethasone (Dex) combined with isoniazid in tuberculous meningitis (TBM) and its effect on peripheral blood T cell subsets.

Methods

A total of 235 patients with TBM were divided into the control group (117 cases) and the observation group (118 cases). Both groups were given conventional treatment, the control group was further given isoniazid, and the observation group was further given Dex combined with isoniazid. The therapeutic effect and improvement of clinical symptoms were evaluated, peripheral blood T lymphocyte subsets and neurological function were observed, and patients' prognosis was evaluated.

Results

The total effective rate of the observation group was higher. The recovery time of cerebrospinal fluid (CSF) pressure, CSF protein content, CSF cell count, and hospital stays in the observation group were shorter. The duration of cervicogenic headache, fever, vomiting, and coma in the observation group was shorter. CD3+ and CD4+/CD8+ proportions in the observation group were higher, and CD8+ proportion was lower. The NIHSS score and MRS score of the observation group were lower, as well as the incidence of adverse reactions.

Conclusion

Dex combined with isoniazid alleviates clinical symptoms and neurological abnormalities and regulates peripheral blood T cell subsets in TBM.

Novel strategies based on natural products and synthetic derivatives to overcome resistance in Mycobacterium tuberculosis

One of the biggest health challenges of today's world is the emergence of antimicrobial resistance (AMR), which renders conventional therapeutics insufficient and urgently demands the generation of novel antimicrobial strategies. Mycobacterium tuberculosis (M. tuberculosis), the pathogen causing tuberculosis (TB), is among the most successful bacteria producing drug-resistant infections. The versatility of M. tuberculosis allows it to evade traditional anti-TB agents through various acquired and intrinsic mechanisms, rendering TB among the leading causes of infectious disease-related mortality. In this context, researchers worldwide focused on establishing novel approaches to address drug resistance in M. tuberculosis, developing diverse alternative treatments with varying effectiveness and in different testing phases. Overviewing the current progress, this paper aims to briefly present the mechanisms involved in M. tuberculosis drug-resistance, further reviewing in more detail the under-development antibiotics, nanotechnological approaches, and natural therapeutic solutions that promise to overcome current treatment limitations.

Maternal HIV Status and Risk of Infant Mycobacterium tuberculosis Infection as Measured by Tuberculin Skin Test

BACKGROUND

The effect of maternal HIV on infant Mycobacterium tuberculosis (Mtb) infection risk is not well-characterized.

METHODS

Pregnant women with/without HIV and their infants were enrolled in a longitudinal cohort in Kenya. Mothers had interferon gamma-release assays (QFT-Plus) and tuberculin skin tests (TST) at enrollment in pregnancy; children underwent TST at 12 and 24 months of age. We estimated the incidence and correlates of infant TST-positivity using Cox proportional hazards regression.

RESULTS

Among 322 infants, 170 (53%) were HIV-exposed and 152 (47%) were HIV-unexposed. Median enrollment age was 6.6 weeks [interquartile range (IQR): 6.1-10.0]; most received Bacillus Calmette-Guerin (320, 99%). Thirty-nine (12%) mothers were TST-positive; 102 (32%) were QFT-Plus-positive. Among HIV-exposed infants, 154 (95%) received antiretrovirals for HIV prevention and 141 (83%) of their mothers ever received isoniazid preventive therapy (IPT). Cumulative 24-month infant Mtb infection incidence was 3.6/100 person-years (PY) [95% confidence interval (CI): 2.4-5.5/100 PY]; 5.4/100 PY in HIV-exposed infants (10%, 17/170) versus 1.7/100 PY in HIV-unexposed infants (3.3%, 5/152) [hazard ratio (HR): 3.1 (95% CI: 1.2-8.5)]. More TST conversions occurred in the first versus second year of life [5.8 vs. 2.0/100 PY; HR: 2.9 (95% CI: 1.0-10.1)]. Infant TST-positivity was associated with maternal TST-positivity [HR: 2.9 (95% CI: 1.1-7.4)], but not QFT-Plus-positivity. Among HIV-exposed children, Mtb infection incidence was similar regardless of maternal IPT.

CONCLUSIONS

Mtb infection incidence (by TST) by 24 months of age was ~3-fold higher among HIV-exposed children, despite high maternal IPT uptake. Overall, more TST conversions occurred in the first 12 months compared to 12-24 months of age, similar in both HIV-exposed and HIV-unexposed children.

QuantiFERON-TB Gold Plus Performance in Children: A Narrative Review

This review summarizes studies evaluating the performance of the QuantiFERON-TB Gold Plus (QFT-Plus) interferon-gamma release assay (IGRA) test for Mycobacterium tuberculosis ( Mtb ) infection in children. Literature searching was conducted using PubMed, MEDLINE and Embase (January 2017 to December 2021) and the terms "children" or "pediatric" and "IGRAs" or "QuantiFERON-TB Gold Plus." Selected studies (N = 14; 4646 subjects) enrolled children with Mtb infection, tuberculosis (TB) disease or healthy children with household TB contacts. Agreement between QFT-Plus and tuberculin skin test (TST) (kappa values) ranged from -0.201 (no agreement) to 0.83 (almost perfect agreement). Assay sensitivity of QFT-Plus (against reference standard of microbiologically confirmed TB disease) was 54.5%-87.3%, with no reported difference in children less than 5 versus greater than or equal to 5 years of age. In individuals less than or equal to 18 years of age, the rate of indeterminate results was 0%-33.3% (2.6% in children <2 years). IGRAs may overcome the limitations of TST in young, Bacillus Calmette-Guérin-vaccinated children.

Cumulative Mycobacterium tuberculosis Infection Incidence (Measured Primarily by Tuberculin Skin Test) Among Infants With Human Immunodeficiency Virus Exposure: Observational Follow-up of an Isoniazid Prophylaxis Trial

Cumulative 24-month Mycobacterium tuberculosis infection incidence (measured primarily by tuberculin skin test [TST]) was high among human immunodeficiency virus exposed but uninfected infants (8.7 [95% confidence interval, 6.3-11.9] per 100 person-years). Trend for decreased TST positivity among infants at trial end (12 months postenrollment) randomized to isoniazid at 6 weeks of age was not sustained through observational follow-up to 24 months of age.

CLINICAL TRIALS REGISTRATION

NCT02613169.

A CD4+ TNF+ monofunctional memory T-cell response to BCG vaccination is associated with Mycobacterium tuberculosis infection in infants exposed to HIV

BACKGROUND

The immunologic correlates of risk of Mycobacterium tuberculosis (Mtb) infection after BCG vaccination are unknown. The mechanism by which BCG influences the tuberculin skin test (TST) remains poorly understood. We evaluated CD4+ T-cell responses in infants exposed to HIV and uninfected (HEU) who received BCG at birth and examined their role in susceptibility to Mtb infection and influence on TST induration.

METHODS

HEU infants were enrolled in a randomised clinical trial of isoniazid (INH) to prevent Mtb infection in Kenya. We measured mycobacterial antigen-specific Th1 and Th17 cytokine responses at 6-10 weeks of age prior to INH randomisation and compared responses between Mtb infected and uninfected infants. Outcomes at 14 months of age included TST, QuantiFERON-Plus (QFT-Plus), and ESAT-6/CFP-10-specific non-IFN-γ cytokines measured in QFT-Plus supernatants.

FINDINGS

A monofunctional mycobacterial antigen-specific TNF+ CD4+ effector memory (CCR7-CD45RA-) T-cell response at 6-10 weeks of age was associated with Mtb infection at 14 months of age as measured by ESAT-6/CFP-10-specific IFN-γ and non-IFN-γ responses (Odds Ratio 2.26; Confidence Interval 1.27-4.15; P = 0.006). Mycobacterial antigen-specific polyfunctional effector memory Th1 responses at 6-10 weeks positively correlated with TST induration in infants without evidence of Mtb infection at 14 months, an association which was diminished by INH therapy.

INTERPRETATION

Induction of monofunctional TNF+ CD4+ effector memory T-cell responses may be detrimental in TB vaccine development. This study also provides mechanistic insight into the association of BCG-induced immune responses with TST induration and further evidence that TST-based diagnoses of Mtb infection in infants are imprecise.

FUNDING

Thrasher Research Fund.

Non-IFNγ Whole Blood Cytokine Responses to Mycobacterium tuberculosis Antigens in HIV-exposed Infants

BACKGROUND

HIV-exposed uninfected (HEU) infants have increased risk of tuberculosis (TB). Testing for Mycobacterium tuberculosis (Mtb) infection is limited by reduced Quantiferon (QFT) sensitivity in infants and tuberculin skin test (TST) cross-reactivity with Bacillus Calmette-Guérin vaccine. Our objective is to assess if non-IFNγ cytokine responses to Mtb-specific antigens have improved sensitivity in detecting Mtb infection in HEU infants compared with QFT.

METHODS

HEU infants were enrolled in a randomized clinical trial of isoniazid preventive therapy (IPT) to prevent Mtb infection in Kenya (N = 300) and assessed at 12 months postrandomization (14 months of age) by TST and QFT-Plus. Non-IFNγ cytokine secretion (IL2, TNF, IP10, N = 229) in QFT-Plus supernatants was measured using Luminex assay. Logistic regression was used to assess the effect of IPT on Mtb infection outcomes in HEU infants.

RESULTS

Three of 251 (1.2%) infants were QFT-Plus positive. Non-IFNγ Mtb antigen-specific responses were detected in 12 additional infants (12/229, 5.2%), all TST negative. IPT was not associated with Mtb infection defined as any Mtb antigen-specific cytokine response (odds ratio = 0.7, P = 0.54). Mtb antigen-specific IL2/IP10 responses had fair correlation (τ = 0.25). Otherwise, non-IFNγ cytokine responses had minimal correlation with QFT-Plus and no correlation with TST size.

CONCLUSIONS

We detected non-IFNg Mtb antigen-specific T-cell responses in 14-month HEU infants. Non-IFNg cytokines may be more sensitive than IFNg in detecting infant Mtb infection. IPT during the first year of life was not associated with Mtb infection measured by IFNg, IL2, IP10 and TNF Mtb-specific responses.

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.