Is bacterial resistance really due to mutation?

Yes, a virus inherits from its predecessors a resistance to penicillin.It pretty much goes along with the inherited lack of an important structure which penicillin targets, this being the cell wall. Most bacterial cells have double layers on their outside. The outermost layer -- the "cell wall" -- is similar to the outer layer of plant cells, but is missing in human and animal cells. This wall must grow along with the cell, or the growing cell will eventually become too big for the wall and burst and die. Penicillins kill bacteria by interfering with the wall-building system. Virii don't even have cells, let alone cell walls, so they are resistant to penicillin in much the same sense that snakes are resistant to athelete's foot.

This is one of my pet peeves.Antibiotic resistance is a significant problem, and getting worse. Over-prescribing of antibiotics is a major contributing factor. Patient insistence on being prescribed antibiotics is a major factor contributing to this major contributing factor. The threat from antibiotic-resistant strains of bacteria is a price we all end up paying for ignorance, even when it is not our own; every prescribing of an antibiotic (whether actually indicated or not) is an opportunity for strains of bacteria to develop resistance (through a process many of the worst offenders are unwilling even to admit exists, called: "evolution"). Often, the prescribing of an antibiotic is a care provider practicing "CYA" in the face of an uncertain diagnosis (it's often favored as a less time-consuming and therefore cheaper alternative to performing expensive diagnostic tests).The problem is made much worse by the many patients who, upon experiencing a relief from symptoms, quit taking the drug. These people make their bodies available to the bacteria as training grounds for increased resistance. Then they go off to work, to the grocery store, and their kids go off to school, exposing everyone with whom they come in contact to increasingly resistant strains -- including those who have made the effort to educate themselves on proper use of antibiotics (which really isn't all that complicated) instead of waving their responsibility in the matter away as belonging to the doctor who gave them the antibiotic.It may be that you were prescribed an antibiotic to control a secondary infection, an opportunistic bacterial infection of the sort which often follows a viral infection; or he may have prescribed it prophylactically, to prevent such an infection. I still say: if you don't know why you got the antibiotic, you should.