The woman with the swollen red leg was selling us one bill of goods after another. She said she had stopped injecting drugs years before; the fresh needle marks on her feet suggested otherwise. She said she had duly taken all the antibiotic pills another hospital had given her, although most people don't finish those prescriptions.
But we didn't raise an eyebrow at the least likely claim of all. Instead we wrote it down carefully in our notes and it became a part of her hospital record, highlighted in red on the computer and set off with an exclamation point, permanently molding her medical life and also, in a way, our own.
This was her life-threatening allergy to penicillin.
About one in 10 Americans reports a serious allergy to the antibiotic penicillin or any of several closely related drugs. Yet in about 90 percent of cases, no serious allergy exists.
Some people are using the word allergy imprecisely. Antibiotics can have all kinds of dreadful side effects, from diarrhea to nerve damage, but most of these are not formally considered allergies.
Some people confuse antibiotics: an older woman once described to me in spine-chilling detail the swollen lips and wheezing that had kept her away from penicillin since before World War II. But penicillin wasn't around then, and she probably had a sulfa allergy instead.
A few people — or, more likely, their doctors — mix up the disease and the treatment. Syphilis and Lyme disease can sometimes dramatically worsen in the hours following effective treatment, but that isn't a drug allergy either.
Some people may have only a mild allergy. Ampicillin in particular can cause a rash that is annoying but not dangerous.
Meanwhile, people with the throat-swelling, heart-stopping immediate reaction to penicillin called anaphylaxis often outgrow it. Fewer than half will remain allergic after five years.
In other words, the chances were good that we could have treated that angry infected leg with a penicillin drug without running into problems. It was by far our best and cheapest option.
But we routinely sidestep this particular gamble. The odds may be strongly in our favor, more than for most of the risks we routinely take, but it is hard to say who is more terrified by the prospect of overriding a patient's allergy history, the patient or the hospital's lawyers.
So a couple of times a week, we briefly consider our options, right and wrong.
The right option is not to proceed like a bunch of cowboys, gleefully administering the penicillin ourselves. The right option is to address the matter with the available scientific tools. A system of skin tests can predict with precision whether a person can safely get penicillin and its many relatives.
At this point in our discussion, if it gets this far, we always look at each other with some confusion. Are the chemicals needed for a skin test available these days? (The major one was off the market for quite a few years but now is back again). Who does the testing, anyway? (It needs an experienced hand. Is that person still working here?)
Somebody should definitely find out the answers, for sure, we say. But at the moment we are in a big hurry. We need to get this woman on treatment so she can get better and vacate that expensive hospital bed for somebody else.
Our patient is not one of the rare individuals who absolutely needs penicillin. Plenty of other antibiotics will help her. These days, only certain patients with syphilis have no good treatment alternatives. For them we deploy not only skin tests (which take about an hour in the right hands) but even the painstaking daylong desensitization procedures that can briefly defuse the immune reaction to the drug.
For every other patient, we head cheerfully down the wrong path. It takes us less than seven seconds to choose among various other antibiotics. They are more expensive than a penicillin drug would be, and also more powerful. They will kill off a lot of innocent intestinal organisms that our patient would probably be better off keeping. They will let drug-resistant variants thrive and escape into the world.
But our patient's leg will get better, and that is our visible focus. The resistant microbial population in her gut, our hospital, our other patients, our community and our very own selves (no man is an island when it comes to microbes) are invisible.
She is only one patient in one hospital, but the sum total of all those decisions in all the patients like her in all the hospitals in the country is chilling. Or rather, it would be chilling, if we had the time to sit down and think about it.
