Evolution by Nancy Kress

Evolution by Nancy Kress (Asimov’s SF, October 1995) begins with an edgy conversation between two mothers over a garden fence about a hospital doctor who has been murdered.

Somebody shot and killed Dr. Bennett behind the Food Mart on April Street!” Ceci Moore says breathlessly as I take the washing off the line.
I stand with a pair of Jack’s boxer shorts in my hand and stare at her. I don’t like Ceci. Her smirking pushiness, her need to shove her scrawny body into the middle of every situation, even ones she’d be better off leaving alone. She’s been that way since high school. But we’re neighbors; we’re stuck with each other. Dr. Bennett delivered both Sean and Jackie. Slowly I fold the boxer shorts and lay them in my clothesbasket.
“Well, Betty, aren’t you even going to say anything?”
“Have the police arrested anybody?”
“Janie Brunelli says there’s no suspects.” Tom Brunelli is one of Emerton’s police officers. There are only five of them. He has trouble keeping his mouth shut. “Honestly, Betty, you look like there’s a murder in this town every day!”  p. 322 (Year’s Best SF, edited by David Hartwell)

This gritty soap opera feel is maintained throughout much of the rest of the story.
We later find that this crime has occurred in a near-future where widespread drug resistance has caused a partial breakdown of the health system, as well as vigilante resistance against the doctors and hospitals who dare to use the one remaining drug, endozine, that has any anti-bacterial efficacy.
Later on in the story Betty’s son Jackie is linked, by an old high school friend who tries to recruit her to the pro-endozine side, to the vigilantes who are violently opposed to its use. We then find out, when the Betty can’t find her son, that the latter’s biological father is a hospital doctor called Salter (there is also some detail about their estrangement, and how Betty did prison time as a teenager when she shot out the windows of Salter’s house and injured a caretaker—I did say it was soap opera-ish).
When Betty goes to the hospital to see Salter to enlist his help in finding Sean (spoiler) there is an overly compressed scene where the news of endozine’s failure is revealed (the CDC have identified a resistant bacterial strain) and, after a huge data dump about this, (the obviously sick) Salter announces he has a solution—which is another bacteria to attack the resistant one. He gets Betty to fetch a syringe, and injects her, and then they leave the hospital just before it is blown up.
Betty then spreads the protective bacteria to everyone she meets.
This story doesn’t entirely work, mostly because the SFnal substance of it is crammed into the long single scene just described—and not in a particularly reader-friendly way (it’s Jargon Central in some places). And there are also a couple of questions that are not answered. Why did Salter get sick if he had the cure? Why does Betty’s vigilante son end up, at the end of the story, with the woman who tried to recruit Betty? On the other hand, some will appreciate the grittiness of the piece (and perhaps its current relevance), and there is some effective writing:

I drive home, because I can’t think what else to do.
I sit on the couch and reach back in my mind, for that other place, the place I haven’t gone to since I got out of [prison]. The gray granite place that turns you to granite, too, so you can sit and wait for hours, for weeks, for years, without feeling very much. I go into that place, and I become the Elizabeth I was then, when Sean was in foster care someplace and I didn’t know who had him or what they might be doing to him or how I would get him back. I go into the gray granite place to become stone.
And it doesn’t work.  p. 335 (Year’s Best SF, edited by David Hartwell)

**+ (Average t0 Good). 9,000 words.