spirocheten

Spir ochetes, or spirochetes, are a phylum of slender, spiral-shaped bacteria known for their distinctive motility and diverse habitats. They are Gram-negative, highly motile, and typically range from 0.2 to 0.5 micrometers in diameter with lengths that vary by species. A key feature is the presence of periplasmic flagella, or axial filaments, embedded between the inner and outer membranes. The rotation of these axial filaments gives a characteristic corkscrew locomotion that enables movement through viscous media and host tissues.

Taxonomically, spirochetes form the phylum Spirochaetota (formerly grouped as Spirochaetes) and include genera such as Treponema, Borrelia, and Leptospira. They are generally Gram-negative or Gram-variable, and many species are fastidious, making laboratory culture difficult.

Ecologically, spirochetes occupy diverse niches. Some are part of the normal microbiota in the oral cavity, genital tract, or intestines of animals; others are free-living in aquatic or soil environments. Several species are notable human or animal pathogens.

Important pathogenic spirochetes include Treponema pallidum, the cause of syphilis; Borrelia burgdorferi sensu lato, a major cause of Lyme disease; various Borrelia species that cause relapsing fever; and Leptospira interrogans, responsible for leptospirosis. Transmission methods vary and can involve vectors, direct contact with bodily fluids, or exposure to contaminated water.

Diagnosis commonly relies on serology and molecular methods, with culture possible only in specialized settings. Treatment typically comprises antibiotics, with regimens tailored to the species and stage of infection.