[NWFLConservative]

Bugs undergo genetic mutations all the time. Sometimes it is the result of random DNA transcription errors during replication or in response to antibiotics. Often times the errors result in bugs that are no longer viable and die, and sometimes it results in bugs which become more virulent or resistant to treatment. Bugs can develop resistance to antibiotics if they are over prescribed, which is an all too common occurrence, and produce what are called "plasmids" which are DNA fragments inside their cells which contain the coding for ways to defeat the actions of some drugs. E. coli is notorious for this, and some strains have been found to contain as many as a dozen different plasmids. It used to be that penicillin (a ß lactam drug) was effective against them. But they eventually mutated to the point where they have plasmids which produce a ß lactamase which breaks down the drug.

In my lab we do C&S (Culture and Sensitivity) on every sample coming in. The "Sensitivity" part entails planting the bug on a large plate and placing various antibiotic saturated disks on the plate. We let it incubate overnight and look at the plate the next day. If the bug grows right up to the disk, it is resistant. If there is a clear "zone of inhibition" around the disk, you can determine the extent of the bug's sensitivity based on the size of the zone. It is not unusual at all to see bugs with resistance to all but one disk. The war between drugs and bacteria is a constant game of "one-up-manship". For very simple one celled organisms, they can be pretty damn sneaky! ☺

[Taffini]

BUMP

Interesting information. Thanks.

[ichabod1]

Bugs can develop resistance to antibiotics if they are over prescribed, which is an all too common occurrence...

Sir, I have heard this charge leveled for many years. What is the mechanism by which overprescribing creates drug-resistant organisms? Is it people that are over-prescribed, or animals? When IS the right time to prescribe antibiotics? Should you withhold antibiotics that *might* help an individual because it might promote drug resistance? Should you let a very sick person die to avoid promotion of drug resistance? How much over-prescribing has to take place to increase the resilience of the bugs? Can you create drug resistant microbes in the lab this way? (Actually, the last question is the only one I'd be very curious to know your views on-the rest I could look up if I was that interested.)

[Straight Vermonter]

Bugs undergo genetic mutations all the time. Sometimes it is the result of random DNA transcription errors during replication or in response to antibiotics.

There isn't actually any "response to antibiotics" and antibiotics do not cause mutations. The stronger bacteria merely survive the antibiotics and pass their superior genes on to the next generation. This is the same as faster horses or smaller dogs being bred, except that it is done accidentally. There is no altering of the genes as in a mutation.