What are the main causes of Antibiotic Resistance ?
Repeated and improper uses of antibiotics are primary causes of the increase in drug-resistant bacteria. While antibiotics should be used to treat bacterial infections, they are not effective against viral infections like the common cold, most sore throats, and the flu.
If I say this it would be a debate. If we talk about the genetic make up of bacteria, they also contain extrachromosomal DNA often known to be plasmid. Plasmid can be transferred and hence an excellent phenomenon used by multiple bacteria to be risistant to certain antibiotics. Development of resistance develops due to mutation rate.
Another phenomenon which is often seen in biofilms are called persister cells. Persister cells are dormant and do not grow. Normal antibiotics react to those whose metabolic process is active or actively growing cells. But for persisters they are dormant and hence antibiotics can not defeat their mechanism.