title: Indications of carbapenem resistance evolution through heteroresistance as an intermediate stage in Acinetobacter baumannii after carbapenem administration.
abstract: We describe an in vivo evolution of an antimicrobial profile from susceptibility to full-resistance to carbapenems, with heteroresistance as an intermediate stage, in an Acinetobacter baumannii strain. Heteroresistance was characterized by the growth of sub-populations within the susceptibility halo in both disk-diffusion and Etest. PCRs for the main A. baumannii carbapenemases were negative. The exact resistance mechanism, diagnostic methods and clinical relevance of heteroresistance in A. baumannii warrant further investigations. This is the first description of such phenomenon in vivo and the second report of heteroresistance to carbapenems in A. baumannii.
authors.affiliation: Laboratory of Microbiology, Hospital São Lucas, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS, Brazil. silvanas@ufcspa.edu.br
authors.forename: Silvana Vargas
authors.initials: SV
authors.lastname: Superti
authors.forename: Daniela de Souza
authors.initials: Dde S
authors.lastname: Martins
authors.forename: Juliana
authors.initials: J
authors.lastname: Caierão
authors.forename: Fabiana da Silva
authors.initials: Fda S
authors.lastname: Soares
authors.forename: Taísa
authors.initials: T
authors.lastname: Prochnow
authors.forename: Alexandre Prehn
authors.initials: AP
authors.lastname: Zavascki
mesh_terms: D000151:Acinetobacter Infections / Q000188:drug therapy / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000187:drug effects*; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D052978:Disk Diffusion Antimicrobial Tests; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D006801:Humans; D015378:Imipenem / Q000494:pharmacology* / Q000627:therapeutic use; D000077731:Meropenem; D010641:Phenotype; D013845:Thienamycins / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D013845:Thienamycins; D015378:Imipenem; D000077731:Meropenem