A Study of Susceptibilities of Leptospira Strain Towards Antibiotics and Indigenous Herbs

Victoria, Ulok (2024) A Study of Susceptibilities of Leptospira Strain Towards Antibiotics and Indigenous Herbs. Masters thesis, Universiti Malaysia Sarawak.

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Abstract

Leptospirosis is a zoonosis caused by pathogenic Leptospira spp.. As for leptospirosis cases has increased over the last decade, thus it's critical to assess the effectiveness of popular antibiotics and medicinal herbs in controlling this disease. Nonetheless, there is minimal evidence on antimicrobial susceptibility of Leptospira isolates and medicinal herbs against Leptospirosis in Malaysia. Hence, the objective of this study is to determine antibiotic susceptibility toward Leptospira spp. in Sarawak. In addition, this study investigates the antimicrobial activity of H. formicarum Jack and B. stenophylla against Leptospira spp. Then to investigate chemical components containing inside indigenous herbs using Column Chromatography and Gas Chromatography-Mass Spectroscopy (GC-MS) methods. Two herbs in Sarawak that are currently tested are Hydnophytum formicarum Jack (family of Rubiaceae), and Boesenbergia stenophylla (family of Zingiberaceae). Twelve isolated local Leptospira strains tested were L. noguchii strain LT796, and L. Borgpetersenii serovar mini (pathogenic Leptospira); and L. wolffii serovar Khorat strain Khorat-H2, and L. inadai serovar Aguaruna strain MW4 (saprophytic Leptospira spp.) isolated from the environment were tested against seven antibiotics (penicillin G, ampicillin, amoxicillin, doxycycline, cefotaxime, chloramphenicol and streptomycin) and crude extract of B. stenophylla and H. formicarum Jack from four different solvents (methanol, ethyl acetate, hexane and chloroform) by using the broth microdilution method. Broth Microdilution method is performed in this study to determine the minimum inhibitory concentrations (MICs) for antimicrobial susceptibilities testing of these selected antibiotics and indigenous herbs against isolated Leptospira spp.. As a result, all Leptospira spp. showed more susceptible toward cefotaxime and erythromycin with MIC90 0.2 µg/mL, as compared to amoxicillin and ampicillin with MIC 0.39 µg/mL. Meanwhile, doxycycline exhibited the highest MIC90 value of 5.938 µg/mL. In the other hand, the present study showed the lowest MIC (125 µg/mL) for all crude extracts has been shown to have higher than the standard antibiotic. However, all crude extract of B. stenophylla and H. formicarum demonstrated good antimicrobial activity against Leptospira spp.. Ethyl acetate is the effective extractant for both H. formicarum Jack and B. stenophylla extractant against both pathogenic and intermediate Leptospira spp. Tuber extract of H. formicarum Jack showed better antimicrobial activity against both pathogenic and intermediate Leptospira spp.. with lowest MIC values of 125 µg/mL and 62.5 µg/mL. In the other hand, the leave extract of B. stenophylla using ethyl acetate of indicate better inhibition against pathogenic Leptospira spp.. compare to rhizome extract with the lowest MIC value of 62.5 µg/mL. Besides, this study deals with the identification of phytochemical constituents from B. stenophylla and H. formicarum Jack by GC-MS analysis. GC-MS confirmed the occurrence of a total of 37 and 39 phytochemical constituents in the different solvent extract of B. stenophylla and H. formicarum Jack, respectively. The results of the study could be utilised as a future reference for the selection of antibiotics and assist the medical practitioner in the treatment of leptospirosis.

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