Genomic characterization of a Brazilian multidrug-resistant Klebsiella pneumoniae ST17 isolate associated with bovine mastitis

This study presents the genomic and phenotypic characterization of a multidrug-resistant Klebsiella pneumoniae (MDR-Kp) isolate (LC808) obtained from a case of bovine mastitis in Brazil. Antimicrobial susceptibility testing revealed an MDR phenotype, indicating resistance to penicillins, cephalosporins, monobactams, aminoglycosides, tetracyclines, fluoroquinolones, and trimethoprim-sulfamethoxazole. The presence of an extended-spectrum β-lactamase (ESBL) was also confirmed. Whole-genome sequencing identified the isolate as sequence type 17 (ST17) and revealed the presence of the KL127 and O13 loci. The resistome contained genes associated with antimicrobial resistance, including bla CTX−M−15 , bla TEM−1 , bla SHV−187 , and bla OXA−1 (β-lactams); aph(6)-Id , aph(3’’)-Ib , aph(3’)-Ia , aac(3)-IIe , and aac(6’)-Ib10 (aminoglycosides); tet(A) (tetracyclines); qnrB17 (fluoroquinolones); and sul2 (sulfonamides). A class 1 integron carrying dfrA14 was also identified. The virulome included type 1 and type 3 fimbriae, a type VI secretion system, and multiple iron-acquisition systems ( fecABCDEIR ). Identifying this clinically relevant lineage that carries multiple resistance and virulence determinants highlights the presence of MDR-Kp in bovine mastitis in Brazil. These findings provide the necessary genomic baseline data to support ongoing genomic surveillance of antimicrobial-resistant bacteria in dairy herds within a One Health framework.