Effectiveness and safety of tuberculosis preventive treatment for contacts of patients with multidrug-resistant tuberculosis: a systematic review and meta-analysis

Update on multidrug-resistant tuberculosis preventive therapy toward the global tuberculosis elimination

Multidrug-resistant tuberculosis (MDR-TB), the deadliest form of tuberculosis (TB), has been included in the 2024 World Health Organization (WHO) priority list of antibiotic-resistant bacterial pathogens owing to its severe public health implications. Almost two billion people worldwide are infected with Mycobacterium tuberculosis; however, the share of MDR-M.tuberculosis remains uncertain. Mathematical modeling estimates that MDR-TB affects nearly three in every 1000 people worldwide, highlighting the urgent need to address TB preventive treatment (TPT) for contacts of MDR-TB cases. Before 2018, close monitoring of contacts of people with MDR-TB was recommended rather than TPT. However, considering the ethical and public health concerns associated with leaving infected individuals untreated, the WHO updated its guidelines in 2018, 2020, and 2022. Despite the limited evidence at the time, the WHO suggested considering quinolone-based TPT for selected high-risk cases. To close this gap in evidence, two large-scale prospective randomized controlled trials were conducted: VQUIN (VQUIN MDR Australia New Zealand Clinical Trials Registry number, ACTRN12616000215426) and TB-CHAMP (TB-CHAMP ISRCTN Registry number, ISRCTN92634082). Both trials evaluated the efficacy of levofloxacin (Lfx) compared with a placebo for MDR-TB after household exposure in adults and children. A combined meta-analysis of the two trials showed a 60% reduction in TB incidence in the Lfx group, and the difference was statistically significant. Based on these results, in 2024, the WHO recommended the use of 6 months of daily Lfx as a TPT for contacts exposed to MDR/rifampicin-resistant TB. This regimen is cost-effective, safe, demonstrates good efficacy, and does not interact with HIV therapies. Despite these promising results, pre-extensively drug-resistance (XDR)-TB (MDR-TB with documented resistance to quinolones) remains an emerging concern. Two ongoing trials will address this challenge: the PHOENIx trial (PHOENIx-MDR TB NCT03568383), which will evaluate the efficacy of delamanid compared with isoniazid for preventing M/XDR-TB after household exposure, and the BRANCH-TB trial (NCT0656848), which will assess the efficacy and safety of 1 month of bedaquiline regimen compared with WHO-recommended TPT regimens. Preventing MDR/rifampicin-resistant TB remains a significant challenge for the global elimination of TB. Although the recent WHO recommendation for 6 months of daily Lf is a promising step, expanding the TPT options for pre-XDR TB and addressing drug intolerance are critical. Ongoing and new trials are essential to develop alternative treatment and achieve TB elimination.

Effect of Bacillus Calmette-Guérin vaccination against Mycobacterium tuberculosis infection in children: an updated systematic review and meta-analysis

OBJECTIVES

To update the understanding of the effectiveness of the Bacillus Calmette-Guérin (BCG) vaccine in preventing tuberculosis (TB) infection in children.

METHODS

PubMed, Web of Science, Cochrane, and Embase were searched from their inception to January 12, 2025. Studies were included if they focused on children under 19 years exposed to pulmonary TB, used interferon-gamma release assays (IGRA) for infection assessment, and reported IGRA-positive outcomes for both BCG and non-BCG groups. Pooled estimates were derived using random-effects meta-analysis, with heterogeneity assessed by the I² statistic.

RESULTS

Total 8242 participants were enrolled in 32 studies. The overall protective effectiveness of BCG against infection was 18%, with a relative risk [RR] of 0.82 (95% confidence interval [CI]: 0.73-0.91], I² = 60%). Subgroup analysis revealed a higher effectiveness of 29% (RR = 0.71 [95% CI: 0.62-0.82], I² = 41%) in low-TB incidence areas, while effectiveness was not significant (RR = 0.95 [95% CI: 0.84-1.09], I² = 55%) in high-TB incidence areas.

CONCLUSIONS

BCG vaccination shows protective effectiveness against TB infection, particularly in low-TB incidence areas. Its effectiveness in high-TB incidence areas remains uncertain, underscoring the need for further research to optimize vaccination strategies in these settings.

A Meta-Analysis of Levofloxacin for Contacts of Multidrug-Resistant Tuberculosis

BACKGROUND

Data from randomized trials evaluating the effectiveness of tuberculosis (TB) preventive treatment for contacts of multidrug-resistant (MDR)-TB are lacking. Two recently published randomized trials that did not achieve statistical significance provide the opportunity for a meta-analysis.

METHODS

We conducted combined analyses of two phase 3 trials of levofloxacin MDR-TB preventive treatment - Levofloxacin for the Prevention of Multidrug-Resistant Tuberculosis (VQUIN) trial and the Levofloxacin preventive treatment in children exposed to MDR-TB (TB-CHAMP) trial. Following MDR-TB household exposure, VQUIN enrolled mainly adults in Vietnam; TB-CHAMP enrolled mainly young children in South Africa. Random assignment in both trials was 1:1 at the household level to daily levofloxacin or placebo for 6 months. The primary outcome was incident TB by 54 weeks. We estimated the treatment effect overall using individual participant data meta-analysis.

RESULTS

The VQUIN trial (n=2041) randomly assigned 1023 participants to levofloxacin and 1018 participants to placebo; TB-CHAMP (n=922) assigned 453 participants to levofloxacin and 469 participants to placebo. Median age was 40 years (interquartile range 28 to 52 years) in VQUIN and 2.8 years (interquartile range 1.3 to 4.2 years) in TB-CHAMP. Overall, 8 levofloxacin-group participants developed TB by 54 weeks versus 21 placebo-group participants; the relative difference in cumulative incidence was 0.41 (95% confidence interval [CI] 0.18 to 0.92; P=0.03). No association was observed between levofloxacin and grade 3 or above adverse events (risk ratio 1.07, 95% CI 0.70 to 1.65). Musculoskeletal events of any grade occurred more frequently in the levofloxacin group (risk ratio 6.36, 95% CI 4.30 to 9.42), but not among children under 10 years of age. Overall, four levofloxacin-group participants and three placebo-group participants had grade 3 events.

CONCLUSIONS

In this meta-analysis of two randomized trials, levofloxacin was associated with a 60% relative reduction in TB incidence among adult and child household MDR-TB contacts, but with an increased risk of musculoskeletal adverse events. (Funded by the Australian National Health and Medical Research Council, UNITAID, and others.).

Impacts of MDR/XDR-TB on the global tuberculosis epidemic: Challenges and opportunities

Tuberculosis (TB) is the world's second-deadliest infectious disease. Despite the availability of drugs to cure TB, control of TB is hampered by the emergence of multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB). The presence of MDR/XDR-TB is alarming due to the low detection rate, high treatment failure, and high mortality. The increasing cases of MDR/XDR-TB are mainly due to the limitations in the diagnostic tests to detect the drug susceptibility of the pathogen, which contribute to the spread of the disease through close contacts. Moreover, inconsistent drug therapy or unsuitable drug regimens could also lead to the subsequent development of drug resistance. The close contacts of an index MDR/XDR-TB patient are at increased risk of developing MDR/XDR-TB. Also, the BCG vaccine may exhibit varying protective effects due to BCG strain diversification, host immune status, exposure to environmental non-tuberculous mycobacteria (NTM), and differences in Mycobacterium tuberculosis (Mtb) subspecies infection, as in the case of sub-optimal protection in the case of Beijing family genotypes of Mtb. This review provides an overview of the current state of drug-resistant tuberculosis (DR-TB) within the context of the global TB pandemic, with a focus on diagnosis, treatment, and the potential impact of BCG vaccination. It highlights the limitations of current approaches and aims to identify opportunities for improving TB control strategies.

The Impact of the Seasonal and Geographical Distribution of Tuberculosis in Sicily: A 6-Year Retrospective Study (2018-2023)

Background: Tuberculosis (TB) continues to be a major public health issue, with high mortality rates reported worldwide. It is worth noting that most of the hospitalizations for tuberculosis in the Sicilian region involve Italian-born individuals, underscoring the need to address this problem. Recent research on the geographic area and seasonality of infectious diseases, including tuberculosis, may aid in developing effective preventive measures. Objectives: This study aimed to evaluate the impact of the season and geographical area on tuberculosis disease prevalence in the Sicilian region. Methods: A retrospective study from January 2018 to May 2023 was conducted on patients with tuberculosis in the Sicilian region by analyzing computerized records on the Infectious Diseases Information System, currently named the Italian National Notification System (NSIS), of the Epidemiology Unit at Policlinico Paolo Giaccone University Hospital of Palermo and the Regional Reference Laboratory for Tuberculosis Surveillance and Control. Results: Eastern and Western Sicily were the geographical Sicilian areas with the highest frequency of patients with tuberculosis (52.2% and 42.6%, respectively). In comparison, Central Sicily had a significantly lower frequency of patients with tuberculosis (5.2%). Regarding the season, autumn was the season with the highest number of notification cases (28.9%), while spring was the season with the lowest frequency of patients with tuberculosis (19.7%). In autumn, we found significantly fewer patients with tuberculosis from Eastern Sicily (39.3%) and Central Sicily (1.5%), while Western Sicily had more patients with tuberculosis (59.3%). In spring, we found significantly more patients with tuberculosis from Eastern Sicily (64.1%), while Western and Central Sicily had significantly fewer patients with tuberculosis (23.9% and 12%, respectively). The presence of patients with tuberculosis did not significantly differ between geographical regions in summer and winter. Conclusions: Geographical area and seasonality significantly impact the distribution of tuberculosis cases in Sicily. These factors may be linked to different climatic conditions across the various geographical areas considered. Our findings suggest that climate can play a critical role in the spread of airborne infectious diseases, such as tuberculosis.