Clonal dissemination of highly virulent Serratia marcescens strains producing KPC-2 in food-producing animals

Serratia marcescens is a Gram-negative bacterium presenting intrinsic resistance to polymyxins that has emerged as an important human pathogen. Although previous studies reported the occurrence of multidrug-resistance (MDR) S. marcescens isolates in the nosocomial settings, herein, we described isolates of this extensively drug-resistant (XDR) species recovered from stool samples of food-producing animals in the Brazilian Amazon region. Three carbapenem-resistant S. marcescens strains were recovered from stool samples of poultry and cattle. Genetic similarity analysis showed that these strains belonged to the same clone. Whole-genome sequencing of a representative strain (SMA412) revealed a resistome composed of genes encoding resistance to β-lactams [bla(KPC-2), bla(SRT-2)], aminoglycosides [aac(6′)-Ib3, aac(6′)-Ic, aph(3′)-VIa], quinolones [aac(6′)-Ib-cr], sulfonamides [sul2], and tetracyclines [tet(41)]. In addition, the analysis of the virulome demonstrated the presence of important genes involved in the pathogenicity of this species (lipBCD, pigP, flhC, flhD, phlA, shlA, and shlB). Our data demonstrate that food-animal production can act as reservoirs for MDR and virulent strains of S. marcescens.