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If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. Colistin is frequently used as a growth factor or treatment against infectious bacterial diseases in animals. In , faecal samples were collected from chickens, cattle, sheep, goats, and pigs in the south of France.
In order to track the emergence of mobilized colistin resistant mcr genes in pigs, samples were re-collected in and included pig faeces, food, and water from the same location. PCR and Sanger sequencing were performed to screen for the presence of mcr genes. The selective culture revealed the presence of bacteria corresponding to 35 different bacterial species including Gram-negative and Gram-positive. Pigs had the highest prevalence of colistin-resistant bacteria with an abundance of intrinsically colistin-resistant bacteria and from these samples one strain harbouring both mcr- 1 and mcr- 3 has been isolated.
The second collection allowed us to identify bacteria and revealed the spread of mcr- 1 and mcr- 3 in pigs. In the other samples, naturally, colistin-resistant bacteria were more frequent, nevertheless the mcr- 1 variant was the most abundant gene found in chicken, sheep, and goat samples and one cattle sample was positive for the mcr- 3 gene. Animals are potential reservoir of colistin-resistant bacteria which varies from one animal to another. Interventions and alternative options are required to reduce the emergence of colistin resistance and to avoid zoonotic transmissions.
Colistin polymyxin E is a cationic polypeptide antibiotic used as a last-line therapeutic drug, to treat bacterial infections, especially carbapenem-resistant Gram-negative bacteria [ 1 ]. Colistin has been used for decades in veterinary medicine as a growth factor [ 2 ].
