My staph infection!

After spending a couple of hours in the hot sun pruning a large shrub (wearing gloves), I noticed something on the inside of my ring finger that looked like a pink blister. After a week or so, a tiny open wound appeared, which, over the days, continued to expand. I sort of freaked out and went to the doctor who seemed unconcerned but prescribed an antibiotic ointment (more about that next week).

Infection at four weeks

The bacteria that likely caused my staph infection is Staphyloccus epidermidis—normal members of everyone’s skin flora. That is, they’re always hanging around our skin and mucous membranes, and comprise about 5% of the 1000 bacteria species that live on our skin. They’re generally not harmful and can even be beneficial by preventing pathogenic organisms from colonizing on your skin. But they are considered “opportunists” and sometimes cause infections if they are able gain a foothold. (They’re also the most common cause of infections that occur on knee and hip replacements.)

The reason that we’re not permanently covered in staph and other infections is that our immune systems produce cells (neutrophils) that kill bacteria that penetrate the skin barrier. But our immune systems may have evolved not to over-react to bacteria, otherwise we’d be in a constant state of inflammation. At the same time, the bacteria have evolved defense mechanisms to protect themselves from being ingested by our immune cells. It’s a very tricky balancing act.

What I have not been able to find out is why otherwise benign bacteria became pathogenic. One friend got a staph infection from a bee sting (common); another has become infected a few times from cat bites. I have concluded that the bacteria must gain their foothold when a very small object—maybe a sticker, in my case—pierces the skin in a certain way under certain conditions. That’s the best I can come up with.

Because all my other wounds have always healed quickly, I always thought my immune system could handle anything that came its way. “Pride goeth before a fall.”

For an introduction to this blog, see I Just Say No; for a list of blog topics, click the Topics tab.