Reduction of colistin recommended

The European Commission asked for this update in response to the discovery of a new mechanism of resistance in bacteria to colistin (caused by the mcr-1 gene). The gene can be transferred between different types of bacteria, potentially causing a rapid development of resistance. The gene was first identified in bacteria (Enterobacteriaceae) in South China, and since then has also been found in the EU and other regions.

In light of the new evidence, the Antimicrobial Advice Ad Hoc Expert Group (AMEG) had been asked to re-evaluate the impact of the use of colistin on human and animal health, the consequences of resistance and what alternative treatments are available. Moreover, the group was asked to consider adequate risk management measures. The advice was endorsed by both the Committee for Medicinal Products for Veterinary Use (CVMP) and the Committee for Medicinal Products for Human Use (CHMP).

Over the course of the next three to four years, all Member States should reduce the use of colistin in animals at least to a target level of 5 mg colistin/population correction unit (PCU). PCU means the estimated weight of livestock and slaughtered animals. If successfully applied, this could result in an overall reduction of approximately 65% in the current sales of colistin for veterinary use at an EU level. This decrease should build on the decrease of colistin sales for veterinary use already seen between 2011 and 2013. Member States are also encouraged to set stricter national targets, ideally below 1 mg colistin/PCU as a desirable level.

In its advice, AMEG underlined that the reduction of colistin sales should not be compensated by increase in the use of other types of antimicrobials, but should be achieved through other measures such as improved farming conditions, biosecurity between production cycles, and vaccination of livestock.

In addition, colistin should be reclassified and added to Category 2 of the AMEG classification system, which includes medicines reserved for treating infections in animals for which no effective alternative treatments exist. This category includes certain classes of antimicrobials listed by the World Health Organization as critically important to human health. Because of the risk posed to public health by their veterinary use, these medicines are subject to specific restrictions.

Colistin or colistimethate sodium has been used for over 50 years in both humans and animals. In human medicines it is a last resort medicine to treat bacterial infections resistant to other antibiotics. In veterinary medicine, colistin has been used to treat infections caused by Enterobacteriaceae in farm animals. Partly due to the development of resistance to other classes of antibiotics, colistin consumption has increased in recent years. Today it is one of the five most commonly used antibiotics in animals within the EU.