how bacteria can natural select to become resistant to antibiotics in decades but not resistant to heat (cooking), ethanol (fermentation), and/or salt after tens of thousands of years of contact w these pressures.

Question

Why is cooking still an effective way of eliminating human pathogens or fermentation or salting? These methods do not eliminate all traces of the bacteria so what is keeping a random mutation from happening that allows, say, e. Coli in beef to become resistant to heat up to 60c or Listeria to resist salt concentrations to the same levels as bacteria which are not infectious and potential beneficial to us that can tolerate?

What is it about antibiotics that makes them so susceptible to creating these random mutations that antibiotics become near obsolete in decades?

In: 24

Answer 1

For bacteria to evolve resistance, it has to be just hot/salty/poisonous enough that some die but others don’t for many bacterial generations. For heat, it’s quite rare (heh) for someone to par-heat their food to say 38C and leave it “cooking” like that for a long time. That is warm enough to start killing bacteria, but not enough to completely kill everything. The non-resistant bacteria die, while the slightly-resistant bacteria survive; that’s (artificial) selection for heat-resistant bacteria. If you kept heating to 45, 50C, all the bacteria would be killed.

For antibiotics, the dosage is measured to kill bacteria over the course of the prescription. If you stop taking it early, it’s like not fully cooking your food; the slightly-resistant bacteria haven’t died yet because the concentration of antibiotic isn’t high enough or hasn’t completely spread throughout your body. That lets them grow and pass on that slight-resistance to their offspring. Repeat this many times, and those bacteria may end up completely resistant to that antibiotic.