No illustrations for this one. I'll leave image searching to the hardy, the curious, and the self-punishing.
...Right. So today I'm going to talk about bacteria. For those of you who want to read about interactions with humans, now's your chance to click away.
I haven't seen a real patient in a month. Last week during Patient-Doctor we went to an art museum. Before that were videotaped exams during which we interviewed standardized patients. (Best moment: Me: "You mentioned you were hard of hearing. Do you wear a hearing aid?" Patient: "What?") Next week is our final reflection session, which will have a few Doctors, ~80 Medical Students, and no Patients.
Don't say I didn't warn you.
Some interesting things about bacteria that are interesting to me and maybe not to you but hopefully to you too:
1. We are outnumbered 10:1 by bacteria on our own turf, our bodies. (Note: this is by number only. I'm not sure about volume. Most bacteria are only a fraction of the size of human cells.)
2. I used to think "flesh-eating bacteria" (necrotizing fasciitis) were a certain species of superbacteria that you somehow pick up (thanks, Cabin Fever). Actually, they're normal bacteria species (or certain strains of normal bacteria) gone bad--instead of causing superficial skin infection, they chomp all the way down to the muscle and nerves underneath.
Many kinds of bacteria can be "flesh-eating," and the scary part is that we're all harboring them on our skin, in our throats, and in our GI tracts right now. They're just not in "flesh-eating mode"--and no one knows exactly what factors in the host or the bacteria trigger the often fatal change.
2a. The less scary part is that nectrotizing fascitis is rare. One doctor said he saw two cases in six years.
2b. (Jim Henson, creator of The Muppets, died from it in 1990.)
3. Actually, the whole "normal bacteria turned bad" thing is true for many infections. About a quarter of us have several strains of Strep in our throats... but we don't have symptoms of the disease. A similar percentage of us have Staph on our skin, in our nose, in our GI tracts, and in our vaginas. Our immune system generally keeps them in check.
4. A vaccine for Lyme disease was developed and made it to the market but was withdrawn because of anti-vaccine sentiment. This is the only example of an approved useful vaccine that is currently not available to the public.
5. We are in a continual arms race against bacteria. We develop an antibiotic that doesn't let bacteria build their cell wall. Bacteria select for an enzyme that neutralizes our antibiotic. We make an antibiotic that inactivates the enzyme. Bacteria select for modifications of their enzyme that don't get inactivated by our drugs. And so it goes.
5a. Note the wording: bacteria "select for" traits that evade our weapons. The mutations exist before we introduce our weapons--they don't develop in response to them. Now the bacteria with previously arbitrary mutations survive, prosper, and share their genes with their friends, lovers, and daughters.
5b. MRSA (methicillin resistant Staph aureus) was first documented in 1961. Now, about one third of people harbor it. Although it used to be found only in hospitals, now it can be acquired in the outside community as well. It is resistant to not only methicillin but many other drugs in similar classes.
Exam on Monday. More facts must come, or I'm not going to pass.
Until then.
Saturday, May 14, 2011
Sunday, May 1, 2011
Unlikelies
I recently ordered thirty dollars' worth of books from a private seller on Amazon. In return, I received an empty box and a refusal from the seller to reship the goods, blaming USPS. USPS predictably remained impenetrable and bureaucratic, offering no recourse or refund.
The innocent woman working in my dorm's business office caught me mid-rant, and she commiserated. "After working here for 15 years, I see what happens--you wouldn't believe how often. Now, I never ship anything using USPS."
Years of experience had exposed her to not-entirely-uncommon mishaps that many individuals do not realize exist. As a result, she had lost faith in the system, preferring to opt out.
I stayed angry for a few days. But would I use the system again? Probably. I wondered how many mishaps it would take for me to change my mind. I wondered if one expensive loss would be enough.
When I was an undergraduate, I was friendly with a clinical geneticist. She was in her late thirties, and she and her husband had opted not to have children. "There's just too much that can go wrong," she told me. There were too many ways chromosomes could break and realign themselves, too many ways a vital piece of genetic material could be lost in a single cell division, too many dangers in utero that could cause physical and mental deformities. "I don't think I'd be able to handle taking care of a child like that."
As a genetic counselor, she explained to couples the risk of having a child born with a particular disease or condition. It was also her job to counsel the parents if said child was born with said condition. Her days were spent considering unlikelies and talking to people whose lives had been touched by unlikelies.
I wondered if she had suddenly come to her decision after an especially sad case, or if her realization had been gradual after years of cumulative sadnesses. I wondered if her risk-averse perspective was in her best interest. She admitted that her biggest fear was regretting her decision twenty years down the line.
A little knowledge may be a dangerous thing, but what about a lot of knowledge?
I've felt my own perspective changing in medical school. You spend your days studying mishaps. Sometime's it's the likelies: one in two men will eventually get cancer, as will one in three women. Many times, though, it's the unlikelies: the debilitating autoimmune attacks, the odd bowel obstructions, the random vessel ruptures. My classmates and I routinely joke that it's a miracle we've made it this long.
Sometimes it seems as though being alive is an unlikely in itself.
I wonder if this sort of thinking is accurate on some level.
I wonder how this perspective will change my decisions.
I wonder if it will be for the better or worse.
I wonder if we're going to go through life permanently skewed.
But I suppose there's no opting out.
The innocent woman working in my dorm's business office caught me mid-rant, and she commiserated. "After working here for 15 years, I see what happens--you wouldn't believe how often. Now, I never ship anything using USPS."
Years of experience had exposed her to not-entirely-uncommon mishaps that many individuals do not realize exist. As a result, she had lost faith in the system, preferring to opt out.
I stayed angry for a few days. But would I use the system again? Probably. I wondered how many mishaps it would take for me to change my mind. I wondered if one expensive loss would be enough.
When I was an undergraduate, I was friendly with a clinical geneticist. She was in her late thirties, and she and her husband had opted not to have children. "There's just too much that can go wrong," she told me. There were too many ways chromosomes could break and realign themselves, too many ways a vital piece of genetic material could be lost in a single cell division, too many dangers in utero that could cause physical and mental deformities. "I don't think I'd be able to handle taking care of a child like that."
As a genetic counselor, she explained to couples the risk of having a child born with a particular disease or condition. It was also her job to counsel the parents if said child was born with said condition. Her days were spent considering unlikelies and talking to people whose lives had been touched by unlikelies.
I wondered if she had suddenly come to her decision after an especially sad case, or if her realization had been gradual after years of cumulative sadnesses. I wondered if her risk-averse perspective was in her best interest. She admitted that her biggest fear was regretting her decision twenty years down the line.
A little knowledge may be a dangerous thing, but what about a lot of knowledge?
I've felt my own perspective changing in medical school. You spend your days studying mishaps. Sometime's it's the likelies: one in two men will eventually get cancer, as will one in three women. Many times, though, it's the unlikelies: the debilitating autoimmune attacks, the odd bowel obstructions, the random vessel ruptures. My classmates and I routinely joke that it's a miracle we've made it this long.
Sometimes it seems as though being alive is an unlikely in itself.
I wonder if this sort of thinking is accurate on some level.
I wonder how this perspective will change my decisions.
I wonder if it will be for the better or worse.
I wonder if we're going to go through life permanently skewed.
But I suppose there's no opting out.
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