Klebsiella oxytoca. Coloured scanning electron micrograph (SEM) of the bacteria Klebsiella oxytoca, resistant to some antibiotic drugs. This type of rod-shaped, Gram-negative bacteria lives in the intestines of humans and animals, and can be pathogenic. Klebsiella sp. bacteria are among the most common causes of infection, and are responsible for urinary tract infections, septicaemia and pneumonia. They are also often found in infected wounds. The bacteria are generally resistant to penicillin and other popular antibiotic drugs. Magnification: x6500 at 6x7cm size.