title: In vitro activity of potential old and new drugs against multidrug-resistant gram-negatives.
abstract: BACKGROUND
  The aim of this study was to evaluate the in vitro susceptibility of MDR gram-negatives bacteria to old drugs such as polymyxin B, minocycline and fosfomycin and new drugs such as tigecycline.
  
  
  METHODS
  One hundred and fifty-three isolates from 4 Brazilian hospitals were evaluated. Forty-seven Acinetobacter baumannii resistant to carbapenens harboring adeB, blaOxA23, blaOxA51, blaOxA143 and blaIMP genes, 48 Stenotrophomonas maltophilia including isolates resistant to levofloxacin and/or trimethoprim-sulfamethoxazole harboring sul-1, sul-2 and qnrMR and 8 Serratia marcescens and 50 Klebsiella pneumoniae resistant to carbapenens harboring blaKPC-2 were tested to determine their minimum inhibitory concentrations (MICs) by microdilution to the following drugs: minocycline, ampicillin-sulbactam, tigecycline, and polymyxin B and by agar dilution to fosfomycin according with breakpoint criteria of CLSI and EUCAST (fosfomycin). In addition, EUCAST fosfomycin breakpoint for Pseudomonas spp. was applied for Acinetobacter spp and S. maltophilia, the FDA criteria for tigecycline was used for Acinetobacter spp and S. maltophilia and the Pseudomonas spp polymyxin B CLSI criterion was used for S. maltophilia.
  
  
  RESULTS
  Tigecycline showed the best in vitro activity against the MDR gram-negative evaluated, followed by polymyxin B and fosfomycin. Polymyxin B resistance among K. pneumoniae was detected in 6 isolates, using the breakpoint of MIC > 8 ug/mL. Two of these isolates were resistant to tigecycline. Minocycline was tested only against S. maltophilia and A. baumannii and showed excellent activity against both.
  
  
  CONCLUSIONS
  Fosfomycin seems to not be an option to treat infections due to the A. baumannii and S. maltophilia isolates according with EUCAST breakpoint, on the other hand, showed excellent activity against S. marcescens and K. pneumoniae.
authors.affiliation: LIM-54, Departamento de Doenças Infecciosas e Parasitárias da Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar 500, 1 andar, sala 112, CEP05403-000 Sao Paulo, SP, Brazil.
authors.forename: Camila
authors.initials: C
authors.lastname: Rizek
authors.affiliation: LIM-54, Departamento de Doenças Infecciosas e Parasitárias da Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar 500, 1 andar, sala 112, CEP05403-000 Sao Paulo, SP, Brazil.
authors.forename: Juliana Rosa
authors.initials: JR
authors.lastname: Ferraz
authors.affiliation: LIM-54, Departamento de Doenças Infecciosas e Parasitárias da Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar 500, 1 andar, sala 112, CEP05403-000 Sao Paulo, SP, Brazil.
authors.forename: Inneke Marie
authors.initials: IM
authors.lastname: van der Heijden
authors.affiliation: LIM-54, Departamento de Doenças Infecciosas e Parasitárias da Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar 500, 1 andar, sala 112, CEP05403-000 Sao Paulo, SP, Brazil.
authors.forename: Mauro
authors.initials: M
authors.lastname: Giudice
authors.affiliation: LIM-54, Departamento de Doenças Infecciosas e Parasitárias da Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar 500, 1 andar, sala 112, CEP05403-000 Sao Paulo, SP, Brazil.
authors.forename: Anna Karina
authors.initials: AK
authors.lastname: Mostachio
authors.affiliation: LIM-54, Departamento de Doenças Infecciosas e Parasitárias da Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar 500, 1 andar, sala 112, CEP05403-000 Sao Paulo, SP, Brazil.
authors.forename: Jorge
authors.initials: J
authors.lastname: Paez
authors.affiliation: University Hospital of University of Londrina, Paraná, Brazil.
authors.forename: Claudia
authors.initials: C
authors.lastname: Carrilho
authors.affiliation: LIM-54, Departamento de Doenças Infecciosas e Parasitárias da Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar 500, 1 andar, sala 112, CEP05403-000 Sao Paulo, SP, Brazil.
authors.forename: Anna Sara
authors.initials: AS
authors.lastname: Levin
authors.affiliation: LIM-54, Departamento de Doenças Infecciosas e Parasitárias da Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar 500, 1 andar, sala 112, CEP05403-000 Sao Paulo, SP, Brazil. Electronic address: costasilviaf@ig.com.br.
authors.forename: Silvia F
authors.initials: SF
authors.lastname: Costa
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D005578:Fosfomycin / Q000494:pharmacology; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000031:analogs & derivatives / Q000494:pharmacology; D011112:Polymyxin B / Q000494:pharmacology; D000078304:Tigecycline
chemical_list: D000900:Anti-Bacterial Agents; D005578:Fosfomycin; D000078304:Tigecycline; D008911:Minocycline; D011112:Polymyxin B
keywords: Fosfomycin; MDR gram-negatives; Minocycline; Polymyxin B; Tigecycline