My neighbor has been told she has osteomyelitis, and she is now being treated with three weeks of antibiotics. If the infection doesn't clear up, they are going to cut her leg off just below the knee. Could you please tell me if this disease can be contagious? I'm a little afraid of being near her, and everyone in our area seems to stays away from her because we know nothing about the disease.

Mrs. C.

Osteomyelitis is an infection of the bone. There are two types of bone infection. In the more common type, an infection starts in the skin, often in a sore or ulcer, and eventually extends into nearby bone. This is common in diabetic patients, who are prone to developing deep sores on the feet. In the other major form of osteomyelitis, microorganisms (usually bacteria) infecting the skin, urinary tract or another area enter the bloodstream and travel in the blood to the bone. In adults, this form of osteomyelitis often involves the spine, while in children, it typically infects long bones such as the one in the thigh.

Osteomyelitis is an important infection because it is difficult to get rid of. Often the infected bone becomes necrotic (dead). Without living tissue, immune system cells are not able to reach the infection to combat it. In addition, antibiotics do not penetrate bone very well, especially in areas of necrosis.

The treatment of osteomyelitis depends on the type of infection. In the type that results from bloodstream infection, called "hematogenous osteomyelitis," the treatment is a four- to six-week course of intravenous (IV) antibiotics. Sometimes, if there is dead bone, surgery is required to remove it. In the form that starts with a sore in the skin, called "contiguous spreading osteomyelitis," surgery is almost always required. The operation is also followed by a long course of antibiotics.

Your neighbor probably has contiguous spreading osteomyelitis. In addition, she may have diabetes. I am a bit surprised that she was told she would lose her leg if the infection does not clear up with one try of antibiotics. It is true that not all cases are cured by antibiotics, but usually there are other options. For example, limited surgery can often be performed to remove the dead bone without amputation. And sometimes a very long course of antibiotics -- or even lifelong antibiotics -- can be a more appealing option than amputation.

Rest assured that her infection is NOT contagious. Your neighbor got a bone infection because of damage to her bone, most probably after a skin wound. Bacteria got in and infected the bone. It is that simple. No one can catch this illness from her.