Sensitivity of different DNA extraction methods and PCR to detect resistance in patients with leprosy stratified by the bacilloscopic index.

INTRODUCTION: Antimicrobial resistance in leprosy is an emerging problem, and the quantitative impact of low bacilloscopic indexes (BIs) on the sensitivity of molecular tests is unknown. We aimed to evaluate the sensitivity of gene sequencing for the detection of mutations related to antimicrobial resistance in Mycobacterium leprae in patients with low BIs using an analytical model. METHODS: Patients with leprosy were included and divided into two groups depending on their BIs (≥ 2+ and < 2+). The sensitivities of the two DNA extraction methods were compared after amplifying and sequencing the repetitive element (RLEP), folP1, rpoB and gyrA in M. leprae. RESULTS: We included 56 patients with leprosy: 35 had BIs less than 2+ (22 had negative slit-skin smear [SSS] results) and 21 patients had BIs greater than or equal to 2+. The sensitivity of the amplification of the RLEP target and the gene sequencing of folP1, rpoB and gyrA was 50 to 70% lower in patients with a BI less than 2+ and was significantly reduced in patients with lower BIs for all targets (p < 0.001). One patient had a mutation in the folP1 gene, and 14 patients had mutations in the gyrA gene, but no mutations related to antimicrobial resistance were found. CONCLUSIONS: We can conclude that the sensitivity of molecular tests is directly related to the BI, but these tests can still detect up to 20% of the targets in patients with BIs < 2+. New strategies to improve the sensitivity for detecting antimicrobial resistance in leprosy patients and reasonable clinical criteria for follow-up and the introduction of alternative treatments must be developed.

Sensitivity of different DNA extraction methods and PCR to detect resistance in patients with leprosy stratified by the bacilloscopic index

ABSTRACT Introduction: Antimicrobial resistance in leprosy is an emerging problem, and the quantitative impact of low bacilloscopic indexes (BIs) on the sensitivity of molecular tests is unknown. We aimed to evaluate the sensitivity of gene sequencing for the detection of mutations related to antimicrobial resistance in Mycobacterium leprae in patients with low BIs using an analytical model. Methods: Patients with leprosy were included and divided into two groups depending on their BIs (≥ 2+ and < 2+). The sensitivities of the two DNA extraction methods were compared after amplifying and sequencing the repetitive element (RLEP), folP1, rpoB and gyrA in M. leprae. Results: We included 56 patients with leprosy: 35 had BIs less than 2+ (22 had negative slit-skin smear [SSS] results) and 21 patients had BIs greater than or equal to 2+. The sensitivity of the amplification of the RLEP target and the gene sequencing of folP1, rpoB and gyrA was 50 to 70% lower in patients with a BI less than 2+ and was significantly reduced in patients with lower BIs for all targets (p < 0.001). One patient had a mutation in the folP1 gene, and 14 patients had mutations in the gyrA gene, but no mutations related to antimicrobial resistance were found. Conclusions: We can conclude that the sensitivity of molecular tests is directly related to the BI, but these tests can still detect up to 20% of the targets in patients with BIs < 2+. New strategies to improve the sensitivity for detecting antimicrobial resistance in leprosy patients and reasonable clinical criteria for follow-up and the introduction of alternative treatments must be developed.

Leprosy detection rate in patients under immunosuppression for the treatment of dermatological, rheumatological, and gastroenterological diseases: a systematic review of the literature and meta-analysis.

BACKGROUND: Recently developed immunosuppressive drugs, especially TNF antagonists, may enhance the risk of granulomatous infections, including leprosy. We aimed to evaluate the leprosy detection rate in patients under immunosuppression due to rheumatological, dermatological and gastroenterological diseases. METHODS: We performed a systematic review of the literature by searching the PubMed, EMBASE, LILACS, Web of Science and Scielo databases through 2018. No date or language restrictions were applied. We included all articles that reported the occurrence of leprosy in patients under medication-induced immunosuppression. RESULTS: The search strategy resulted in 15,103 articles; finally, 20 articles were included, with 4 reporting longitudinal designs. The detection rate of leprosy ranged from 0.13 to 116.18 per 100,000 patients/year in the USA and Brazil, respectively. In the meta-analysis, the detection rate of cases of leprosy per 100,000 immunosuppressed patients with rheumatic diseases was 84 (detection rate = 0.00084; 95% CI = 0.0000-0.00266; I2 = 0%, p = 0.55). CONCLUSION: Our analysis showed that leprosy was relatively frequently detected in medication-induced immunosuppressed patients suffering from rheumatological diseases, and further studies are needed. The lack of an active search for leprosy in the included articles precluded more precise conclusions. TRIAL REGISTRATION: This review is registered in PROSPERO with the registry number CRD42018116275 .