Many representatives belonging to the Flavobacteriaceae family have a very relevant role as fish pathogens, and the genus Chryseobacterium has been frequently isolated as the causative agent of disease ocurring in freshwater fish and have been previously isolated from diseased farmed salmonids in Chile. T his study characterize d using whole-genome sequencing and phenotypic analysis, two β-lactamases belonging to the CIA and IND groups , which catalyzes the degradation of third-generation cephalosporin and carbapenem antimicrobials, respectively, produced by the resistant strain FP29 (Fig. 1) , recovered from fin lesion samples of diseased Atlantic salmon, Salmo salar, during one Flavobacteriosis outbreak occurred in a freshwater farm located in Southern Chile.
The FP29 strain was identified as Chryseobacterium sp. by using biochemical tests and by whole genome comparison analysis, using the PATRIC bioinformatics platform, observing that is genetically most closely related to the reference strain Chryseobacterium vrystaatense , showing an OrthoANI value of 88.96%. Amino acid sequences of the BlaCIA and BlaIND proteins synthesized by the FP29 strain exhibited highest identities to Bla CIA-4 and BlaIND-4 (71.92% and 80.17%, respectively) (Fig. 2) . It was confirmed that the detected BlaCIA and BlaIND proteins conferred a resistance phenotype , and FP29 strain exhibited resistance to the 3rd -generation cephalosporins cefotaxime , ceftriaxone and caftazidime, as well as resistance to the carbapenems imipenem and meropenem. In addition, the activity of cephalosporine cefotaxime (CTX) was inhibited by the clavulanic acid (CTL) (Fig. 3A) , whereas the activity of metallo -β-lactam meropenem (MRP) was inhibited by dipicolinic acid (MRPDP) (Fig. 3B). In conclusion, the results of this study demonstrated, for the first time, the simultaneous production of the BlaCIA and BlaIND β –lactamases by a Chryseobacterium strain isolated from reared Atlantic salmon affected with Flavobacteriosis in Chilean freshwater salmonid farming, reinforcing the hypothesis that this taxonomic group may serve as an important environmental reservoir of these enzymes .