Molecular Surveillance of Antimicrobial Resistance of Mycobacterium leprae from Leprosy Patients in Zhejiang Province, China

Novel mutations found in Mycobacterium leprae DNA repair gene nth from central India

INTRODUCTION

The importance of DNA repair enzymes in maintaining genomic integrity is highlighted by the hypothesis that DNA damage by reactive oxygen/nitrogen species produced inside the host cell is essential for the mutagenesis process. Endonuclease III (Nth), formamidopyrimide (Fpg) and endonuclease VIII (Nei) DNA glycosylases are essential components of the bacterial base excision repair process. Mycobacterium leprae lost both fpg/nei genes during the reductive evolution event and only has the nth (ML2301) gene. This study aims to characterize the mutations in the nth gene of M. leprae strains and explore its correlation with drug-resistance.

METHOD

A total of 91 M. leprae positive DNA samples extracted from skin biopsy samples of newly diagnosed leprosy patients from NSCB Hospital Jabalpur were assessed for the nth gene as well as drug resistance-associated loci of the rpoB, gyrA and folP1 genes through PCR followed by Sanger sequencing.

RESULTS

Of these 91 patients, a total of two insertion frameshift mutations, two synonymous and seven nonsynonymous mutations were found in nth in seven samples. Sixteen samples were found to be resistant to ofloxacin and one was found to be dapsone resistant as per the known DRDR mutations. No mutations were found in the rpoB region. Interestingly, none of the nth mutations were identified in the drug-resistant associated samples.

CONCLUSION

The in-silico structural analysis of the non-synonymous mutations in the Nth predicted five of them were to be deleterious. Our results suggest that the mutations in the nth gene may be potential markers for phylogenetic and epidemiological studies.

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.

Epidemiological characteristics of leprosy during the period 2005-2020: A retrospective study based on the Chinese surveillance system

Background

Jiangsu Province is located in the Yangtze River Delta region, with a total area of 107,200 square kilometers. Since 1949, over 55,000 cases have been registered, with Taixing accounting for the highest number of patients. The proportion of new cases with MB and G2D was higher compared to other regions. As a result, Jiangsu has been considered a priority area for public health interventions in China.

Methods

This paper mainly described the population, time, and spatial distribution of the newly detected leprosy cases in Jiangsu Province between 2005 and 2020. In this study, all the data were entered into Microsoft Excel and SPSS for the descriptive analysis. ArcGIS was applied to create statistical maps, and Geoda was used to conduct spatial autocorrelation analysis with local Moran's I statistics (LISA). The epidemiological data were obtained from LEPMIS. In addition, population data were obtained from the Statistical Yearbook of Jiangsu Province.

Results

During the study period, 363 new cases were reported. Of these, 232 were men and 131 were women (1.77:1). The mean age at diagnosis was 60.56 years, and no adolescent cases were identified. Three hundred and twenty-seven (90.08%) were diagnosed with MB and 36 (9.92%) with PB. 31.68% (115/363) of the patients presented with G2D. Farmers accounted for 74.9%, and most cases were identified in skin clinics (248, 68.32%). We observed a decreasing trend in detection rate, with a higher concentration of new cases diagnosed between July and October. Spatial analysis showed that the new cases were primarily distributed in the northwest of Jiangsu province, and Suqian has the highest incidence of leprosy. Special attention should be paid to Wuzhong, a county with a potential risk of inter-provincial transmission. Furthermore, 55 new cases came from other Chinese provinces but lived in Jiangsu.

Conclusion

The NCDR of leprosy decreased, but the new cases showed disabilities, a sign of the late diagnosis. The results indicated that some regions were still suffering from the burden of leprosy. Thus, we recommend that the government should adopt effective strategies to promote leprosy control. The main priorities for eliminating new cases were to provide sustainable financial support, improve the quality of clinical services, strengthen preventive intervention and rehabilitation services for disabilities, provide health education among high-risk populations, and explore new approaches.

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.