Antibiotics are antimicrobial compounds used to treat bacteria-caused infections. However, they are used not only on humans, but also on animals and agricultural crops. The antibiotic resistance genes that come out as residue from farms and human habitats can contaminate the environment.
Based on their chemical structure, there are several types of antibiotics: penicillins, tetracyclines, cephalosporins, macrolides, aminoglycosides etc. All of them are anti-infectives derived from bacterial sources (there are also treatments for bacterial infections that are not derived from bacteria).
Antibiotics are used to treat various conditions caused by bacteria, among which:
However, because of excessive use, antibiotics are no longer as efficient in treating infections, as many people have developed an antibiotics resistance.
Antibiotic toxicity usually does not derive from the use of antibiotics as such, but rather from their discharge into natural environments hitherto pristine. This contamination means that antibiotic-resistant bacteria are selected in environments where antibiotic pollution is widespread. This, in turn, leads to a much decreased efficiency of antibiotics on population that actually need them.