Becky is a 53-year-old woman living in seattle, washington, with her husband tim and their dog tipper. even though they both have full-time jobs, becky and tim try to get out every weekend and do something active—kayaking, hiking, or cycling. while becky loves the physical activities, her favorite is the two-week vacation that she and tim take every year. they rent a house on the washington coast and spend their time gathering crabs, harvesting clams, and relaxing. on the last weekend of their vacation, becky and tim always host a big dinner party featuring fresh crabs and clams. this year the dinner party is a huge success— everyone has a great time, and the dungeness crabs are particularly delicious. the morning after the party, becky wakes up and doesn’t feel very well—her stomach is upset, and she feels a little bit nauseated. tim jokes that it’s probably because she drank too much wine at the party; he’s sure that she’ll feel better in a few hours. but as the morning goes on, becky starts to feel worse, and then she starts vomiting. she decides to lie down and rest for a while. a few hours later, tim goes to check on becky. she says that she has a headache and is dizzy; the vomiting hasn’t stopped. tim grows concerned as becky talks because she isn’t making sense, and she seems to be confused. worried that something is seriously wrong with becky, tim takes her to the emergency room (er).

at the er, becky’s physical exam is normal. the mental assessment confirms confusion and disorientation. the doctor orders blood and urine lab analysis and admits becky to the hospital. the blood and urine cultures come back negative for any microbes. becky’s confusion gets worse, and she begins experiencing weakness in her arms and legs. even though becky and tim told the doctor she hadn’t suffered any head injuries, the doctor orders computed tomography (ct) of her head. the ct scan, also known as a cat scan, consists of a series of x-ray images taken from multiple angles and then combined by a computer to provide cross-sectional and three-dimensional views. the results come back normal. urgently seeking a diagnosis, the doctor sits down with becky and tim to go over the preceding days again—where had they gone, what had they done, what had they eaten? becky is having a hard time remembering anything from the last few days. as tim recounts their meals, the doctor asks where they got their crab and clams and how much they ate. tim said he had only a bite of crab, but becky ate a lot. the doctor suspects that becky was poisoned by the crabs and orders a lab test for a toxin. the results of the test come back positive. becky has amnesic shellfish poisoning (asp) from the contaminated crab. although there is no antidote for the toxin, in nonsevere cases such as becky’s, the toxin will eventually pass from the system. becky receives supportive care in the hospital for three weeks; by the time she is discharged, she has made a complete recovery.

questions

why did becky's doctor provide only supportive care? why weren't antimicrobials part of her treatment?

becky's illness was caused by a diatom from the pseudo-nitzchia genus. how are diatoms different from other eukaryotic cells? do they have any features found in prokayotes?