Bad Bugs

I was at the International Society of Microbial Ecology’s (ISME) biennial meeting in Montreal a week and a half ago. This is the largest gathering of microbial ecologists in the world; close to 3,000 of us gathered to present data on all kinds of things from the human microbiome, to life at the bottom of the ocean, to the latest, greatest techniques. The focus of this meeting is on good bugs, the microorganisms that make up the vast majority of microbes on the planet, and, in fact, provide all kinds of health benefits to us humans, and to the Earth in general. It’s not quite a microbe lovefest, but it comes close.

I was giving a talk on Friday, a dreaded time slot, since it was the last day of a five day meeting. Thursday evening, around 6:30, I sat down in a large hall, cavernous is a better description, to hear Penny Chisholm from MIT give a special award lecture on Prochlorococcus. This is the most abundant photosynthetic microbe in the ocean, and makes a substantial contribution to the production of the oxygen we breath everyday. Penny and others only discovered Prochlorococcus back in the 1980’s, and she’s been studying it ever since, and has made many remarkable subsequent discoveries. It was a great talk, however, just as she started I noticed a little tightness in my right wrist, and was surprised to see that it was visibly swollen, indeed, most of my fore-arm was swollen. Initially I thought I was having an allergic reaction, although to what, I didn’t know, since I wasn’t aware of my arm coming in contact with anything that could have been allergenic.

After Penny’s talk, the swelling hadn’t gotten any better, but didn’t seem much worse. I had dinner with my friend Andreas, and went back to the place I was staying to finish a few details on my talk. I was beginning to think this was not an allergic reaction. My arm was uncomfortable, but didn’t really hurt. Although it was a little red and warm, it didn’t have the hallmarks of an infection. I began to worry it might be a blood clot or deep vein thrombosis (DVT), not a good condition, especially with some family history of blood clots and strokes.

The swelling in my right forearm, 16 hours after starting antibiotics, starting to get better

The swelling in my right forearm, 16 hours after starting antibiotics, starting to get better

Needless to say, it was a pretty sleepless night. Should I go to the ER and cancel my talk? Was I ready for my talk? ISME is a prestigious meeting in my field, and it’s an honor to be an invited speaker, even on a Friday. Still, it would suck to be remembered as the guy who had a massive stroke in the middle of his ISME talk. At any rate, in the morning, I still felt OK, the swelling was a little worse, but still not painful, or more widespread. So I did the talk, which went fine, and was pleasantly surprised that the room was far fuller than I expected. I then immediately headed home for Maine. Perhaps this wasn’t the wisest decision, but 6 hours later I was at the ER in Augusta.

The nurse practitioner looked at my arm for 20 seconds, and said, it looks like a DVT, a blood clot, and then said the good news was that clots in your arm don’t go to your heart. That seemed like a relief, although I didn’t have time to ask whether or not they could go to your brain, but maybe, in my case, she didn’t think that would have mattered much. I was given an ultrasound that can detect clots, a chest x-ray, an EKG, and blood work. Essentially everything came back negative, which left the likely cause cellulitis.

Is there where the bad bugs got under my skin?

Is there where the bad bugs got under my skin?

Cellulitis is a bacterial infection that happens just under the skin. It is usually caused by Staphylococcus or Streptococcus, two common skin bacteria that occasionally can get under the outer skin layer or epidermis. Untreated it is quite dangerous, since the bacteria can move from the epidermal layer into the blood, or into the bone, where they can cause real problems, including septic shock and death. The thing with cellulitis is that it normally requires a cut, an abrasion, a hang nail, or some other significant break of skin. As someone who enjoys outdoor activities, a month, and sometimes a week, does not go by that I don’t have some kind of skin abrasion, yet right now my arm was remarkably unscathed.

Where had these bad bugs come from, and how had they spread so quickly? Presumably I had been unlucky enough to come in contact with an especially virulent strain of Staph or Strep that was adept at getting under the skin and growing rampantly. That’s the thing with some benign-seeming bacteria. If they develop some trick, or bag of tricks that make them much better at getting across the skin or other defensive barrier the body has, then they can cause infections. This is the process of virulence, and many of my medical microbiology colleagues devote their research careers to understanding what make bad bugs virulent.

As a microbiologist, who thinks of bacteria as beneficial, it was a stark reminder of how dangerous they can be, and how even under the most benign circumstances your life can suddenly be at risk from an infection. I have a pretty good immune system, and don’t normally get infections. The last time I took antibiotics for a skin infection, I was ten years old, and it was a dog bite (a tormented dashund is a dangerous animal).

I went to several talks at ISME about how dramatically antibiotics can change our human microbiome, often for the worse. Indeed, for a brief moment after the nurse handed me my first dose of antibiotics, I considered letting my body fight off the infection. I gave myself a better than 50:50 chance that I’d make it OK, which was also about the same odds of a divorce, if I told my wife I wasn’t going to take the pills. Then I tipped my hat to Alexander Fleming, the discoverer of antibiotics, and swallowed the pills.

David Emerson

About David Emerson

David Emerson is a professional scientist at the Bigelow Laboratory for Ocean Sciences who studies bacteria that live literally between a rock and a hard place. The views expressed here are his alone.