ULTRASTRUCTURAL MORPHOLOGY STUDY AND OPTIMIZATION OF GROWTH CONDITIONS FOR LEPTOSPIRA INTERROGANS

Abstract

Leptospirosis is one of the often-neglected fatal zoonotic diseases endemic to most developing countries. The disease transmits mostly through contact of rodent urine contaminated with pathogenic Leptospira in the environment. The objectives of this study were to observe and understand the varied Leptospira interrogans ultrastructures, and to optimise the growth condition of the bacterium to better prepare for further evaluation and making of treatments against the bacterium. The ultrastructure of the bacterium was investigated using transmission electron microscopy. In this study, we have documented the varied terminal regions (hooked-end, entangled end, and horseshoe structure), Gram-negative-like cell wall, protoplasmic cylinder with or without flagella, detached flagella, cytoplasmic membrane, cytoplasmic formations extruding the cell wall, a variety of bud and outer membrane vesicle formations, and other peculiar features unique to Leptospira. These ultrastructures could be influencing the pathogenicity of a Leptospira strain but information on them is not well reported, hence the need for more morphological studies on this genus of bacteria. Furthermore, we investigated the growth of the bacterium by comparing the growth curves under different conditions. The necessity of serums and shaking incubation for faster growth and higher Leptospira yield were determined. It was observed that shaking incubation was essential for its optimum growth as the bacterium is aerobic. This study focuses on the many basics of Leptospira interrogans that were not much mentioned or discussed in other studies and would pave way for more detailed investigations of these characteristics and ultimately help in understanding possible approach for diagnostic and treatment in future.