Enterobacter cloacae bacteria, coloured scanning electron micrograph (SEM). Enterobacter cloacae is a Gram-negative, rod-shaped (bacillus) bacterium. Members of the genus Enterobacter exist in water, soil, sewage and the intestinal and urinary tracts of humans and animals. E. cloacae may be the cause of urinary tract and respiratory tract infections in hospital patients with lowered immunity, and may also infect wounds on the skin. These bacteria often show a resistance to multiple antibiotics. Magnification: x10,000, when printed 15cm wide.