spirochaetales spirochaetales the spirochaetales are an order of spirochete bacteria. some species within this order are known to causes syphilis, lyme disease, relapsing fever, and other illnesses. spirochaetales a microscopic photograph of fluorescent-stained spirochaeta americana scientific classification domain: bacteria phylum: spirochaetota class: spirochaetia order: spirochaetalesbuchanan 1917 (approved lists 1980) families borreliaceae gupta et al. 2014 sphaerochaetaceae hördt et al. 2020 spirochaetaceae swellengrebel 1907 (approved lists 1980) "termitinemataceae" song et al. 2021 treponemataceae robinson 1948 (approved lists 1980)