Transmission of bla NDM in Enterobacteriaceae among animals, food and human.

Despite carbapenems not being used in animal, Carbapenem-Resistant-Enterobacterales (CRE), particularly New-Delhi-metallo-β-lactamase-producing-CRE (NDM-CRE), are prevalent in livestock. Concurrently, the incidence of human infections caused by NDM-CRE is rising, particularly in children. Although positive association between livestock production and human NDM-CRE infections at national level was identified, the evidence of direct transmission of NDM originating from livestock to humans remains largely unknown. Here we conducted a cross-sectional study in Chengdu, Sichuan Province to examine the prevalence of NDM-CRE in chickens and pigs along the breeding-slaughtering-retail chains, in pork in cafeterias of schools, and in colonisations and infections from a children's hospital, and examined the correlation of NDM-CRE among animals, foods and humans. Overall, the bla NDM increases gradually along the chicken and pig breeding (4.70%/2.0%) - slaughtering (7.60%/22.40%) - retail (65.56%/34.26%) chains. The slaughterhouse has become a hotspot for cross-contamination and amplifier of bla NDM . Notably, 63.11% pork from school cafeteria were positive for bla NDM . The prevalence of bla NDM in intestinal and infection samples from children's hospital was 21.68% and 19.80%, respectively. WGS analysis revealed the sporadic, not large-scale, clonal spread of NDM-CRE along the chicken and pig breeding-slaughtering-retail chain, with further spreading via IncX3- bla NDM plasmid within each stage of whole chains. Whist clonal transmission of NDM-CRE is predominant in children's hospital. The IncX3- bla NDM plasmid was highly prevalent among animals and humans and accounted for 57.7% in Escherichia coli and 91.3% in Klebsiella pneumoniae . Attention should be directed towards the IncX3 plasmid to control the transmission of bla NDM between animals and humans.