Distribution of microorganisms and main resistances of all bloodstream infections across the three study periods.

3GC, third generation cephalosporin (cefotaxime, ceftriaxone, ceftazidime); AST, antimicrobial susceptibility testing; BSI, bloodstream infection; carbapenem (imipenem, meropenem); ID, identification; P0, pre-intervention period; P1, intervention period 1; P2, intervention period 2. Natural AmpC producers identified during the study periods: Citrobacter freundii, Enterobacter aerogenes, Enterobacter cloacae, Hafnia alvei, Serratia marcescens. Non-natural AmpC producers identified during the study periods: Citrobacter koseri, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Salmonella spp.