Epidemiological and genomic analysis of Acinetobacter baumannii strains from retailed raw meat.

Acinetobacter baumannii causes hospital-acquired infections in human patients with compromised immune system. Strains associated to nosocomial infections are often resistant to carbapenems and belong to few international clones (IC1-11). A. baumannii strains have been found in extra-hospital sources including food products. While molecular epidemiology of A. baumannii is well described in hospital settings, extra-hospital settings remain poorly investigated. In the frame of two screening campaigns for the presence of Gram-negative bacteria in retailed raw meat, we collected 70 A. baumannii isolates. To investigate if there was a genetic link between food isolates and those causing infections in humans, a core-genome pyMLST analysis was conducted including genomes from different sources as well as representatives of the IC1-11 (n = 224) retrieved from the NCBI database. Strains from raw meat were genetically diverse with 49 sequence types present among the 70 isolates. The core-genome phylogenetic analysis demonstrated that some A. baumannii strains from raw meat shared high genomic similarity with strains associated to human infections carrying carbapenem-resistance genes and belonging to IC11 and other clonal complexes (CC) that are emerging globally, like CC33. Strains from raw meat were able to acquire genes conferring carbapenem-resistance in vitro. If A. baumannii cannot be considered as a food-borne pathogen, colonization of raw meat can favor the propagation of this species in the community, facilitating the entrance of novel clones in the hospital environment. Once entering hospital settings, susceptible clones could turn into multidrug-resistant lineages under strong selective pressure. To avoid this risk, accurate hands and kitchen utensils hygiene should be recommended to all those in contact with raw meat.