The klebsiella are a group of bacteria characterized by a rod shape, no distinct cell wall, and a pointed end. As with many groups of bacteria, many of the bacteria within the klebsiella group are harmless to humans and are commonly found on humans. However, some of them can cause common infections in persons with weak immune systems such as the very young, the very old, or patients with cancer. They can be involved in pneumonia, urinary tract infections, septicemia, diarrhea, meningitis and ankylosing spondylitis. It is one of the most common hospital transmitted infections.