Colistin is an antibiotic that was first used in medicine in 1959. Although the drug fell from favor in the 1970s due to the potential for serious side effects, physicians at the beginning of the 21st century brought the drug back into use to combat infections caused by organisms resistant to more modern drugs. Inhaled colistin is primarily used as a treatment for lung infections of people with cystic fibrosis, but it may also be used to treat lung infections in other people which do not respond to other antibiotics.
Antibiotic resistance is a significant problem facing medicine. The term "resistance" describes a situation where a bacterial species used to be killed by a particular antibiotic, but now is immune. This poses problems when a person is infected with bacteria and the regular treatments do not work. To combat this, doctors need to have other antibiotics in reserve, which can cure the infection.
Inhaled colistin is an example of an antibiotic that a doctor may have to use instead of regular treatments to cure an infection. Colistin is effective in killing bacteria that are part of the Gram negative group. This group of bacteria contains some of the most important of infectious organisms. One example is Pseudomonas aeruginosa, which can be lethal to people with cystic fibrosis.
The main reason colistin was rejected in favor of other drugs was for safety concerns. It can cause damage to the kidneys and to the nervous system. People suffering from dangerous infections of the lungs, however, may, on balance, prefer to take the risk of side effects against the potentially lethal effects of the infection. The advantage of inhaled colistin over intravenous colistin for lung infections is that the aerosolized drug can get to the affected tissues directly, but a doctor may also administer antibiotic as an injection so the drug gets into the entire body.
Generally, the main use of inhaled colistin, as of 2011, is for people with drug resistant lung infections who also suffer from cystic fibrosis. Sometimes, though, the drug may also be used in people who do not have cystic fibrosis, but who have life-threatening lung infections such as pneumonias. In these cases, inhaled colistin may be used as a last resort, due to the risk of serious side effects. Another potential use of inhaled colistin, as of 2011, is in the preparation of lung transplant patients for surgery. Theoretically, colistin may kill off existing strains of bacteria that are resistant to many antibiotics, so that when the patient receives the new lung, the likelihood of infection with drug-resistant bacteria is lowered.