Bacteria antibiotic resistance occurs when bacterial pathogens evolve and become capable of counteracting the effects of one or more antibiotics which they should be susceptible to. This is a form of drug resistance. The increased and wide-spread use of antibiotics has made this issue of drug resistance a large phenomenon world-wide.
Antibiotics function by taking advantage of the difference between a host and the organism infecting the host cells. Antibiotics are either considered to be broad or narrow spectrum drugs, depending on whether they act on G+ or G- strains, or both. Broad spectrum antibiotics act on both strains, whereas narrow spectrum drugs only act on G+ strains.
For example, penicillin is a narrow spectrum antibiotic which takes advantage of the fact that bacterial cells produce rigid cell walls and mammalian cells lack cell walls. Penicillin has a selective toxicity which inhibits the production of an enzyme required in the transpeptidation reaction for constructing the bacterial cell wall. Therefore, penicillin kills bacterial cells by inhibiting the formation of their cell wall as they cannot maintain cell pressure without that support.
Bacterial antibiotic resistance can result from the misuse of a drug, for instance not taking a drug's full course. For example, a patient prescribed penicillin who does not take the complete course may not kill off all bacterial cells. This will leave surviving bacteria behind which may become mutated and subsequently, harder to kill. This mutation will get passed on and may become further mutated overtime, creating a bacterial culture which is effective at fighting the effects of penicillin. Other factors which can cause bacterial antibiotic resistance include:
- Natural abilities
- Using a broad spectrum drug when a narrow spectrum drug should be prescribed
- Transfers from animals to humans (ingestion, close contact, through environment)
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