The Genetic Feature Study Of Bla_NDM-1-carrying Plasmid From Acinetobacter Baumannii Of Pig Origin

Recent published studies have revealed that enterobacteriaceae, like E. coli and Klebsiella, isolated fromseveral Indian centers are resistant to many antibiotics including some highly potent antibiotics likecarbapenems. It has been proposed that this resistance is because of a carbapenemase enzyme called NDM-1（NewDelhiMetallo-betalactamase-1）. This carbapenemase is class B carbapenemase also calledmetallolactamases as they require zinc at their active site. This enzyme is coded by agene called bla_NDM-1orgene NDM-1. Infections caused by such bacteria are associated with high morbidity and mortality. Two classesof antibiotics i.e., polymyxins （colistin） and glycylcyclines （tigecyclines）, have shown in vitro activity againstNDM-1harboring enterobacteriaceae.In this study,1800healthy pig’s rectum swabs we were collected from several pig farms in Fujian andShandong provinces,3000samples from lung, upper jaw lymphaden and liquor pericardii from the diseasepigs in a veterinary hospital from Guangdong, the4800smmples had been detected with8mg/L meropenemnutrient medium and obtain3960meropenem-resistance bacteria, the resistance rate was82.5%. A bla_NDM-1gene positive bacterial was isolated among the samples form Guangdong province （all of the samples werefrom257pigs, the iaolates rate was0.36%）, it was identified as Acinetobacter baumannii via23S rRNAsequencing, and susceptible to five kinds of β-lactams antibiotics, one kind of fluoroquinolone antibiotics andone kind of glycylcycline antibiotics. Its horizontal transmission capacity was confirmed by filter mating andelectrotransformation. The sequence indicate that pNDM-BJ01share85%nucleotide homology with the blaNDM-1gene positive human origin plasmid pNDM-BJ01, both have the same gene scaffold，such as conjugaltransfer region, antibiotics resistance region and T4SS system, the GC%of the antibiotics resistance regionwas>60%, distinctly higher than the adjacence region, suggest that the region may come from plasmid orchromosome in other bacterial via recombinant or integration. upstream and downstram in the pNDM-BJ01possess the ISAba125, but only one ISAba125located in the upstream of bla_NDM-1in the pNDM-AB,confirmed that the ISAba125in the downstream of bla_NDM-1plays a different role.