A woman is brought to the emergency department where you are

A woman is brought to the emergency department where you are working triage. She has an extremely swollen right lower leg. You see what appears to be an old surgical wound in the mid-calf, with rough scar tissue surrounded by purplish-red skin. She is in a lot of pain and her husband speaks for her. He tells you that three weeks age she had a group of moles removed from that area. It had appeared to heal initially, but three days ago the incision area started looking bigger rather than smaller. She did not return to the physician, hoping the condition would resolve itself. In the past three days the area has begun to swell and become very hot. You call the attending physician immediately because you know that this is a serious condition. The patient is sent straight to surgery where the wound is debrided. Gram-positive cocci growing in chains are recovered from the wound. She is transferred to intensive care and put on high-dose intravenous antibiotics for the next 18 hours, but the next evening her leg is amputated below the knee. She remains in the hospital for two months following surgery and requires long-term antibiotic therapy and multiple skin grafts on her upper leg. What condition did this patient have! What features suggest that it is not Clostridium perfringens gangrene? Why was amputation the best solution for the infection in this case?

Solution

Answer:

Case 1.5:

1.  The patient had gangrene caused by Streptococcus, most likely Streptococcus pyogenes (Group A strep), the same strep that causes strep throat. It\'s also called flesh-eating bacteria. Staphylococcus does not appear in chains on the gram stain, strep does. That\'s how it can be said that it is Streptococcus and not Staphylococcus.

The biggest hint that it is not Clostridium perfingens is that Clostridium perfingens are rod shaped. But also Clostridium perfingens are commonly found in the intestines of humans, so it is unlikely that the infection in her leg was caused by this bacterium because the wound would have had to come in contact with feces directly or indirectly.

2. Gangrene spreads very quickly. Streptococcus pyogenes can infect a even a minor cut or scrape and spread extremely rapidly through the body. Within a few days, large areas of tissue need to be surgically removed to prevent the infection from becoming fatal. So, the leg required amputation or the patient would have most likely died.