Emergence and transmission of Carbapenem-resistant Enterobacteriaceae blaNDM-5 gene in healthy pigs in Baise, Guangxi, China: a discovery

A total of 366 tonsillar tissue samples were collected from healthy free-range pigs owned by farmers across 12 districts in Baise City, Guangxi, China. This initiative successfully isolated six strains of Carbapenem-Resistant <i>Enterobacteriaceae</i> (CRE), including four strains of <i>Escherichia coli</i>, and one of <i>Klebsiella aerogenes</i> and <i>Morganella morganii</i>. Assessments utilizing Carbapenemase inhibitor enhancement test, in conjunction with the ResFinder resistance gene database, revealed that five strains carried the <i>bla</i> _NDM-5 gene, while one strain possessed the <i>bla</i> _NDM-1 gene. The overall positivity rate for CRE was determined to be 1.64%. Conjugation tests further demonstrated the ability of the <i>bla</i> _NDM genes to transfer to recipient strains. Additionally, an analysis of the genetic environment surrounding the <i>bla</i> _NDM genes showed similarities among the genes within the same geographic region, suggesting that these strains may have originated from a common ancestor and spread horizontally among different clones. This study provides valuable insights into the transmission of CRE among free-range farmers in Baise City, Guangxi, China.