Department of Medical Microbiology & Parasitology, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, Kubang Kerian, Kelantan 16150, Malaysia.
Hospital Universiti Sains Malaysia, Universiti Sains Malaysia Kampus Kesihatan, Jalan Raja Perempuan Zainab 2, Kota Bharu, Kelantan 16150, Malaysia.
Int J Environ Res Public Health. 2021 Mar 10;18(6):2834. doi: 10.3390/ijerph18062834.
Despite modern medicine, there is an increasing trend for cases of the bacterial infection leptospirosis, and this has led to the exploration of alternative medicines from various sources including plants. The aim of this study was to investigate the in vitro anti-leptospiral activity of extracts alone and combined with penicillin G, ceftriaxone, and doxycycline. Antimicrobial susceptibility testing was performed using the microdilution broth technique upon methanol extract (ME), aqueous extract (AE), and antibiotics against the serovars Australis, Bataviae, Canicola, and Javanica, to determine minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). The results were analyzed using an ELISA microplate reader combined with microscopic analysis. Synergy testing using a checkerboard assay was performed to determine the fractional inhibitory concentration index values of extracts combined with antibiotics against leptospires. Scanning electron microscopy (SEM) was used to investigate morphological changes of leptospires caused by potential anti-leptospiral agents alone and combined with antibiotics. The MICs and MBCs for extracts ranged from 100 to 400 µg/mL for AEs and from 400 to 800 µg/mL for MEs. Penicillin G was the most effective anti-leptospiral drug, with MICs and MBCs ranging from <0.01 to 0.78 and <0.01 to 3.13 µg/mL, respectively, followed by ceftriaxone, with both MICs and MBCs ranging from 0.05 to 0.78 µg/mL, and doxycycline, with MICs and MBCs ranging from 0.39 to 3.13 µg/mL and 12.5 to 25 µg/mL, respectively. Combinations of extracts and antibiotics did not show synergistic effects on all tested serovars, with some combinations demonstrating antagonistic effects. SEM analysis, however, showed distorted surfaces. AE performed better anti-leptospiral activity than ME. The morphological effects of extract alone and its combination with antibiotic on cells revealed promising anti-leptospiral properties.
尽管现代医学不断发展，但细菌感染钩端螺旋体病的病例却呈上升趋势，这促使人们从植物等各种来源探索替代药物。本研究旨在研究甲醇提取物（ME）、水提取物（AE）单独及与青霉素 G、头孢曲松和强力霉素联合应用时对 5 种血清型（Australis、Bataviae、Canicola 和 Javanica）钩端螺旋体的体外抗钩端螺旋体活性。采用微量稀释肉汤技术进行抗菌药敏试验，测定最小抑菌浓度（MIC）和最小杀菌浓度（MBC）。采用酶联免疫吸附试验（ELISA）微孔板读数仪结合显微镜分析对结果进行分析。采用棋盘微量稀释法测定提取物与抗生素联合对钩端螺旋体的部分抑菌浓度指数（FICI）值，以确定协同作用。采用扫描电子显微镜（SEM）观察潜在抗钩端螺旋体药物单独及与抗生素联合作用后钩端螺旋体的形态变化。AE 的 MIC 和 MBC 范围为 100-400 µg/mL，ME 的 MIC 和 MBC 范围为 400-800 µg/mL。青霉素 G 是最有效的抗钩端螺旋体药物，其 MIC 和 MBC 范围分别为<0.01-0.78 和<0.01-3.13 µg/mL，其次是头孢曲松，其 MIC 和 MBC 范围分别为 0.05-0.78 µg/mL，强力霉素的 MIC 和 MBC 范围分别为 0.39-3.13 µg/mL 和 12.5-25 µg/mL。并非所有测试血清型的提取物与抗生素联合均表现出协同作用，有些组合表现出拮抗作用。然而，SEM 分析显示表面变形。AE 的抗钩端螺旋体活性优于 ME。单独使用提取物及其与抗生素联合应用对 细胞的形态影响显示出有希望的抗钩端螺旋体特性。
