Mycoplasmas are atypical bacteria that live as intra- or extracellular parasites.
Chlamydiae are bacterial intracellular pathogens which cause widespread infections in humans.
Lyme disease exhibits a variety of symptoms that may be confused with immune and inflammatory disorders.
Chlamydia trachomatis primarily causes polyarthritis. Chlamydophila pneumoniae not only causes arthritis but also affects the nervous system and the heart, which renders the differential diagnosis difficult.