The development of drug resistance in bacteria is a natural process that can't be stopped. However, it can be slowed. Resistance is currently developing at an alarming rate because of inappropriate and unnecessary antibiotic use.

Inappropriate use in healthcare settings includes using antibiotics when they are not needed for treatment, prescribing the wrong type of antibiotic for treatment, and prescribing antibiotics for an inappropriate duration.

According to the CDC, an antibiotic prescription is inappropriate half the time. For instance, antibiotics do not resolve viral infections such as the common cold, influenza (flu), most bronchitis, most sore throats, and the majority of sinus infections. However, unnecessary antibiotic use for these viral infections is still widespread.

In food animals, antibiotics are sometimes added to livestock food and water to promote growth and prevent disease. More than half of antibiotics currently made are used to enhance livestock growth. This contributes to bacteria becoming resistant to drugs important for human health.

It is not the drug, it is the bacteria that becomes resistant to drugs. Most drugs target the bacterial antigens present on the its cell wall. Most bacteria are initially sensitive to the given antibiotic. Few bacteria may escape death and study the structural pattern of the given drug; and will change their antigen structure inorder to form resistance to that particular antibiotic. This forces scientists to develop stronger antibiotics (next generation Class II, III etc antibiotics). Usually such bacterial resistance develop when a patient don't complete his/her recommended drug dose prescribed by their doctor. (ex) The symptoms of a particular disease disappear in approx 3 days, but your doctor will prescribe medicine for 10 days. A patient will stop his medicine in 3 days and the disease causing bacteria in the host body are not completely eliminated. The pathogens reappear with the disease again in a more virulent fashion.

The development of drug resistance in bacteria is a natural process that can't be stopped. However, it can be slowed. Resistance is currently developing at an alarming rate because of inappropriate and unnecessary antibiotic use.

Inappropriate use in healthcare settings includes using antibiotics when they are not needed for treatment, prescribing the wrong type of antibiotic for treatment, and prescribing antibiotics for an inappropriate duration.

According to the CDC, an antibiotic prescription is inappropriate half the time. For instance, antibiotics do not resolve viral infections such as the common cold, influenza (flu), most bronchitis, most sore throats, and the majority of sinus infections. However, unnecessary antibiotic use for these viral infections is still widespread.

In food animals, antibiotics are sometimes added to livestock food and water to promote growth and prevent disease. More than half of antibiotics currently made are used to enhance livestock growth. This contributes to bacteria becoming resistant to drugs important for human health.

@ Janani replied very well that "It is not the drug, it is the bacteria that becomes resistant to drugs". Bacteria employ following mechanisms in attaining drug resistance:

•Enzymatic deactivation of antibiotics

•Decreased cell wall permeability to antibiotics

•Altered target sites of antibiotic

•Efflux mechanisms to remove antibiotics

•Increased mutation rate as a stress response

Bacteria, fungi, protists, helminths, viruses and cancer cells in their pathogenic states have developed drug resistance because they need to survive, and there is an unavoidable process called evolution. It really is all about evolutionary arms race, we develop new drugs and then they undergo genetic changes to counteract the new killer-molecules.

We still cannot kill HIV because of its rapid resistance to any powerful drug we can deliver. Malaria (falciparum) is on the rise because of its unusual complexity to ward off our best regiment of antimalarials.

Your question and a million more will be asked theses days, especially in a period were drugs which hitherto were effective are no more. I agree with all the answers previously given, in addition behavioral aspect of the patients can not be left out. When we fail to completely cure a disease by not accurately following the dosage instructions, we give the pathogens including bacterial and viruses the opportunity to develop resistance to the treatment regime. So lack of compliance to dosage instructions is also one of the causes of resistance development.