[editor-surveyor]

"So now there is no sulfa drug resistance extant within living bacterial populations?"

Is your reading comprehension really that low?

Or are you just that ignorant of history?

Or both?

"Do you think that, given the disappearance of resistance to sulfa drugs over the past 40 years, that new resistant strains would not develop as soon as the sulfa drugs were reintroduced?"

I see that you do not understand the concept of demographics. Some are resistant because the resistance is "on" in their genes, while others are not resistant because resistance is "off." The distribution of "on" and "off" sub populations can flow either way, depending on the use or disuse of the toxin, but the species retains the capacity for both conditions.

[allmendream]

You didn't say it was turned off. You said sulfa drug resistance had “disappeared”.

But I expect someone who doesn't know what they are talking about to keep changing their story.

So when you treat an infection with antibiotics that kill 99.99% of the population; why didn't those bacteria turn “on” their antibiotic resistance?

The truth of the matter is that antibiotic resistance is associated with different alleles or the presence of absence of these resistance genes on a plasmid.

The ones that die, die because they lack the proper plasmid or genetic allele. Among the surviving population you find the “correct” plasmid or allele, and it passes on to 100% of the next generation.