Mycoplasma genitalium bacteria, illustration. M. genitalium is a small parasitic bacterium. It is a sexually transmitted organism that causes non-gonococcal urethritis in men and several inflammatory reproductive tract syndromes in women such as cervicitis, pelvic inflammatory disease, and infertility. As of 2018, its developing resistance to antibiotics means there are fears it may spread out of control as a 'superbug'. The bacterium is bottle-shaped with a terminal tip organelle that enables M. genitalium to glide along moist mucous surfaces, and to adhere to surfaces such as red blood cells. It has the smallest genome (total genetic material) of all known living organisms.