Equal rates of drug resistance in leprosy cases with relapse and recurrent /chronic type 2 reaction; Time to revise the guidelines for drug resistance testing in leprosy

Implications of drug resistance in leprosy: disease course, reactions and the use of novel drugs

Leprosy remains a significant neglected tropical disease despite the goal of elimination having been achieved in various endemic nations over the past two decades. Reactional episodes complicate the disease course, resulting in deformities and disability. The main aim of treatment is to kill Mycobacterium leprae and decrease the bacterial load, which could help prevent further bacilli transmission. A major concern in breaking the chain of transmission and possibly for recurrent reactions is the role of drug-resistant bacilli. Though some data is available on the background prevalence of drug resistance in leprosy, there is a paucity of studies that look for resistance specifically in leprosy reactions. Administration of long-term steroids or immunosuppressants for chronic and recurrent responses in the presence of drug resistance has the twin effect of perpetuating the multiplication of resistant bacilli and encouraging the dissemination of leprosy. The increasing trend of prescribing second-line drugs for leprosy or type 2 reactions without prior assessment of drug resistance can potentially precipitate a severe public health problem as this can promote the development of resistance to second-line drugs as well. A comprehensive multicenter study, including drug resistance surveillance testing in cases of reactions, is necessary, along with the current measures to stop the spread of leprosy. Here, we have detailed the history of drug resistance in leprosy, given pointers on when to suspect drug resistance, described the role of resistance in reactions, methods of resistance testing, and the management of resistant cases with second-line therapy.

Leprosy reactions: New knowledge on pathophysiology, diagnosis, treatment and prevention

Leprosy, or Hansen's disease, caused by Mycobacterium leprae and Mycobacterium lepromatosis, is a chronic granulomatous infectious disease. Leprosy reactions, characterised by neurocutaneous inflammation, complicate the disease's indolent course, leading to significant morbidity. However, limited knowledge of reaction pathophysiology stems from a lack of experimental models and the abrupt onset of reactional episodes, posing challenges in delineating initial pathogenic steps. In type 1 reactions, ongoing studies explore the roles of interferon-gamma which results in increased interleukin (IL)-15 and autophagy. Leprosy reactions also exhibit an increase in T helper 17 (Th17) and a decrease in T-regulatory cell (Treg) populations, resulting in diminished tumour growth factor-beta and heightened IL-6 and IL-21 production. Exploring the pathogenesis of erythema nodosum leprosum (ENL) reveals insights into neutrophils, Toll-like receptor 9, B-cells, myeloid-derived suppressor cells, IL-10 pathway and neurotrophins. Noteworthy therapeutic targets include increased expression of cyclooxygenase 2 and vascular endothelial growth factor. Early reaction diagnosis is crucial to limit neural damage, with high-resolution ultrasonography showing promise in detecting minimal nerve involvement. Therapies for ENL management, such as thalidomide, methotrexate, apremilast, minocycline and tumour necrosis factor-alpha inhibitors, hold potential. This review addresses recent advances in leprosy reaction pathogenesis and diagnostics, offering therapeutic insights and preventive strategies to mitigate their onset.

Morphological Index as a Sensitive Marker of Drug Resistance in Leprosy: A Case Series

Resistance to antileprosy drugs is one of the main contributors for the persistence of leprosy in the present era. In the absence of universal antimicrobial resistance (AMR) surveillance through the national program, the indications for resistance testing remain a important dilemma to clinicians. WHO recommendations mainly focus on clinical relapse, which could be picked up late with continued transmission and repeated leprosy reactions in the patient. We report here a series of eighteen leprosy cases who were tested for AMR in view of the positive morphological index after completion of multidrug therapy, chronic Erythema nodosum leprosum, and clinical relapse.

High frequency of ofloxacin resistance patterns of Mycobacterium leprae from India: An indication to revisit second line anti-leprosy treatment regimen

OBJECTIVES

Drug resistance in leprosy is an emerging concern, leading to treatment failures, recurrences, and potential spread of resistant Mycobacterium leprae in the community. In this study, we aimed to assess drug resistance prevalence and patterns amongst leprosy patients at a tertiary care referral hospital in India.

METHODS

Mutations in drug resistance determining regions for dapsone, rifampicin, and ofloxacin of the M. leprae genome in DNA extracted from skin biopsies of 136 leprosy patients (treatment-naive = 67, with persistent skin lesions = 35, with recurrence = 34) were analysed by polymerase chain reaction followed by Sanger sequencing. Wild-type strain (Thai-53) was used as a reference strain.

RESULTS

Resistance mutations were identified in a total of 23 patients, constituting 16.9% of the cohort. Within this subset of 23 cases, resistance to ofloxacin was observed in 17 individuals (12.5%), while resistance to both dapsone and rifampicin was detected in three patients each (2.2% for both). The occurrence of ofloxacin resistance showed minimal disparity between recurrent and treatment-naive cases, at 17.6% and 16.4%, respectively. Dapsone resistance emerged in two treatment-naive cases and one case with persistent skin lesions. Notably, none of the treatment-naive cases or those with recurrence/relapse exhibited rifampicin resistance. Subsequently, no statistically significant correlation was identified between other clinical variables and the presence of antimicrobial resistance.

CONCLUSIONS

The occurrence of resistance to the current multidrug therapy regimen (specifically dapsone and rifampicin) and to ofloxacin, a secondary antileprosy medication in M. leprae, represents a concerning scenario. This calls for an expansion towards bactericidal drug options and the establishment of robust surveillance for drug resistance in countries burdened with high leprosy rates. Moreover, the introduction of stringent antimicrobial stewardship initiatives is imperative. As a single centre study, it represents a limited, cross-sectional view of the real situation in the field.

Critical observation of WHO recommended multidrug therapy on the disease leprosy through mathematical study

Leprosy is a skin disease and it is characterized by a disorder of the peripheral nervous system which occurs due to the infection of Schwann cells. In this research article, we have formulated a four-dimensional ODE-based mathematical model which consists of the densities of healthy Schwann cells, infected Schwann cells, M. leprae bacteria, and the concentration of multidrug therapy (MDT). This work primarily aims on exploring the dynamical changes and interrelations of the system cell populations during the disease progression. Also, evaluating a critical value of the drug efficacy rate of MDT remains our key focus in this article so that a safe drug dose regimen for leprosy can be framed more effectively and realistically. We have examined the stability scenario of different equilibria and the occurrence of Hopf-bifurcation for the densities of our system cell populations with respect to the drug efficacy rate of MDT to gain insight on the precise impact of the efficiency rate on both the infected Schwann cell and the bacterial populations. Also, a necessary transversality condition for the occurrence of the bifurcation has been established. Our analytical and numerical investigations in this research work precisely explores that the process of demyelination, nerve regeneration, and infection of the healthy Schwann cells are the three most crucial factors in the leprosy pathogenesis and to control the M. leprae-induced infection of Schwann cells successfully, a more flexible version of MDT regime with efficacy rate varying in the range η∈(0.025,0.059) for 100-120 days in PB cases and 300 days in MB cases obtained in this research article should be applied. All of our analytical outcomes have been verified through numerical simulations and compared with some existing clinical findings.

Global prevalence of resistance to rifampicin in Mycobacterium leprae: A meta-analysis

OBJECTIVES

As the only bactericidal drug in multidrug therapy is rifampicin, monitoring of antimicrobial resistance is important in leprosy patients. Therefore, we conducted a meta-analysis on the resistance of Mycobacterium leprae (M. leprae) to rifampicin and estimated drug resistance in different therapeutic states and regions.

METHODS

Embase, Medline, PubMed, and Web of Science were searched to identify studies between 1 January 1993 and 1 January 2022. Two independent reviewers extracted study data. Pooled cumulative incidences were computed using random-effects meta-analyses.

RESULTS

We included 32 papers describing the resistance of M. leprae to rifampicin (pooled cumulative incidences, 11% [95% confidence interval {CI}, 7% to 15%]). Therapeutic states and regional distribution were obtained for subgroup analyses. A total of 51 of 1135 new cases (pooled incidence, 10% [95% CI, 5% to 16%]) and 81 of 733 relapsed cases (pooled incidence, 20% [95% CI, 13% to 27%]) had rifampicin resistance. A total of 139 participants, including 11 patients with rifampicin resistance (pooled incidence, 42% [95% CI, -21% to 105%]), were nonresponsive and intractable cases. The incidence of rifampicin resistance was highest in the Western Pacific (pooled incidence, 21% [95% CI, 13% to 29%]) and lowest in the Americas (pooled incidence, 4% [95% CI, 1% to 7%]).

CONCLUSIONS

Drug resistance testing and a robust and rigorous surveillance system are recommended to detect the prevalence of drug resistance in leprosy.

Drug Resistance (Dapsone, Rifampicin, Ofloxacin) and Resistance-Related Gene Mutation Features in Leprosy Patients: A Systematic Review and Meta-Analysis

Dapsone (DDS), Rifampicin (RIF) and Ofloxacin (OFL) are drugs recommended by the World Health Organization (WHO) for the treatment of leprosy. In the context of leprosy, resistance to these drugs occurs mainly due to mutations in the target genes (Folp1, RpoB and GyrA). It is important to monitor antimicrobial resistance in patients with leprosy. Therefore, we performed a meta-analysis of drug resistance in Mycobacterium leprae and the mutational profile of the target genes. In this paper, we limited the study period to May 2022 and searched PubMed, Web of Science (WOS), Scopus, and Embase databases for identified studies. Two independent reviewers extracted the study data. Mutation and drug-resistance rates were estimated in Stata 16.0. The results demonstrated that the drug-resistance rate was 10.18% (95% CI: 7.85–12.51). Subgroup analysis showed the highest resistance rate was in the Western Pacific region (17.05%, 95% CI:1.80 to 13.78), and it was higher after 2009 than before [(11.39%, 7.46–15.33) vs. 6.59% (3.66–9.53)]. We can conclude that the rate among new cases (7.25%, 95% CI: 4.65–9.84) was lower than the relapsed (14.26%, 95 CI%: 9.82–18.71). Mutation rates of Folp1, RpoB and GyrA were 4.40% (95% CI: 3.02–5.77), 3.66% (95% CI: 2.41–4.90) and 1.28% (95% CI: 0.87–1.71) respectively, while the rate for polygenes mutation was 1.73% (0.83–2.63). For further analysis, we used 368 drug-resistant strains as research subjects and found that codons (Ser, Pro, Ala) on RpoB, Folp1 and GyrA are the most common mutation sites in the determining region (DRDR). In addition, the most common substitution patterns of Folp1, RpoB, and GyrA are Pro→Leu, Ser→Leu, and Ala→Val. This study found that a higher proportion of patients has developed resistance to these drugs, and the rate has increased since 2009, which continue to pose a challenge to clinicians. In addition, the amino acid alterations in the sequence of the DRDR regions and the substitution patterns mentioned in the study also provide new ideas for clinical treatment options.

Systematic Review of Survival Analysis in Leprosy Studies-Including the Following Outcomes: Relapse, Impairment of Nerve Function, Reactions and Physical Disability

Leprosy is a public health problem in South American, African and Oceanian countries. National programs need to be evaluated, and the survival analysis model can aid in the construction of new indicators. The aim of this study was to assess the period of time until the outcomes of interest for patients with or exposed to leprosy by means of survival analysis surveys. This review researched articles using the databases of PubMed, Science Direct, Scopus, Scielo and BVS published in English and Portuguese. Twenty-eight articles from Brazil, India, Bangladesh, the Philippines and Indonesia were included. The Kaplan-Meier method, which derives the log-rank test, and Cox's proportional hazards regression, which obtains the hazard ratio, were applied. The mean follow-up until the following outcomes were: (I) leprosy (2.3 years) in the population who were exposed to it, (II) relapse (5.9 years), (III) clinical manifestations before, during and after treatment-nerve function impairment (5.2 years), leprosy reactions (4.9 years) and physical disability (8.3 years) in the population of patients with leprosy. Therefore, the use of survival analysis will enable the evaluation of national leprosy programs and assist in the decision-making process to face public health problems.

Epidemiological scenario of leprosy in marginalized communities of India: Focus on scheduled tribes

The Scheduled Tribes (STs) are designated among the most disadvantaged social groups in India. Until the year 2005 (pre-elimination era of leprosy in India), several leprosy-specific control field programmes were implemented, which have been discontinued subsequently. Since then, leprosy diagnosis and treatment have been integrated with General Health Services. Thereafter, specialized expertise for the early diagnosis of leprosy has been gradually diminishing, especially at the peripheral clinics in remote areas. Hence, leprosy cases usually remain undetected for a long time and persist as endemic reservoirs. The tribal population of India accounts for just 8.6 per cent of the overall population. However, 18.5 per cent of the new leprosy cases were detected within the tribal community in the year 2020, indicating a disproportionately high burden of leprosy among the tribal population. Recent data suggest that these health disparities can be mainly related to the increased marginalization of STs as compared to other communities. This shows the need to further explore the current situation of leprosy in STs so that suitable interventions can address the contributing factors, leading to health inequalities in disadvantaged socio-economic groups. Therefore, this review aims to present the current distribution of leprosy in marginalized communities with a special emphasis on STs. Further, this review discusses how resources might be mobilized for such communities to find and treat undetected leprosy patients in STs to enable effective control of leprosy through early detection and timely treatment.