<unk>  (from the Greek leptos, meaning fine or thin, and the Latin spira, meaning coil) is a genus of spirochaete bacteria, including a small number of pathogenic and saprophytic species.<unk>  was first observed in 1907 in kidney tissue slices of a<unk> sis victim who was described as having died of "yellow fever."
Leptospira
Brucella
Francisella
Yersinia
Salmonella
Listeria
Bacteroides
Streptococcus