title: In vitro activity of a polyhexanide-betaine solution against high-risk clones of multidrug-resistant nosocomial pathogens.
abstract: OBJECTIVE
  To determine the in vitro activity of a polyhexanide-betaine solution against collection strains and multidrug-resistant (MDR) nosocomial isolates, including high-risk clones.
  
  
  METHODS
  We studied of 8 ATCC and 21 MDR clinical strains of Staphylococcus aureus, Enterococcus faecium, Enterococcus faecalis, Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa, including the multiresistant high-risk clones. The MICs and MBCs of a 0.1% polyhexanide-0.1% betaine solution were determined by microdilution. For each species, strains with the highest MICs were selected for further experiments. The dilution-neutralization test (PrEN 12054) was performed by incubating bacterial inocula of 106CFU/mL for 1min with undiluted 0.1% polyhexanide-betaine solution. The CFUs were counted after neutralization. Growth curves and time-kill curves at concentrations of 0.25, 1, 4, and 8×MIC, were performed. MICs of recovered strains were determined when regrowth was observed in time-kill studies after 24h of incubation. Strains with reduced susceptibility were selected by serial passage on plates with increasing concentrations of polyhexanide-betaine, and MICs were determined.
  
  
  RESULTS
  Polyhexanide-betaine MIC range was 0.5-8mg/L. MBCs equalled or were 1 dilution higher than MICs. The dilution-neutralization method showed total inoculum clearance of all strains. In time-kill curves, no regrowth was observed at 4×MIC, except for S. aureus (8×MIC). Increased MICs were not observed in time-kill curves, or after serial passages after exposure to polyhexanide-betaine.
  
  
  CONCLUSIONS
  Polyhexanide-betaine presented bactericidal activity against all MDR clinical isolates tested, including high-risk clones, at significantly lower concentrations and time of activity than those commercially used.
authors.affiliation: Unidad Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen Macarena, Sevilla, Spain; Red Española de Investigación en Patología Infecciosa (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain. Electronic address: rlopezrojas@hotmail.com.
authors.forename: Rafael
authors.initials: R
authors.lastname: López-Rojas
authors.affiliation: Unidad Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen Macarena, Sevilla, Spain; Red Española de Investigación en Patología Infecciosa (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Felipe
authors.initials: F
authors.lastname: Fernández-Cuenca
authors.affiliation: Unidad Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen Macarena, Sevilla, Spain.
authors.forename: Lara
authors.initials: L
authors.lastname: Serrano-Rocha
authors.affiliation: Unidad Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen Macarena, Sevilla, Spain; Red Española de Investigación en Patología Infecciosa (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain; Departamento de Microbiología, Universidad de Sevilla, Sevilla, Spain.
authors.forename: Álvaro
authors.initials: Á
authors.lastname: Pascual
mesh_terms: D001419:Bacteria / Q000187:drug effects*; D001622:Betaine / Q000008:administration & dosage / Q000494:pharmacology*; D001645:Biguanides / Q000008:administration & dosage / Q000494:pharmacology*; D003428:Cross Infection / Q000382:microbiology*; D004202:Disinfectants / Q000008:administration & dosage / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D012996:Solutions
chemical_list: D001645:Biguanides; D004202:Disinfectants; D012996:Solutions; C031233:polihexanide; D001622:Betaine
keywords: Antiseptics; Antisépticos; Betaine; Betaína; Biocidas; Biocides; Infección de heridas; Polihexanida; Polyhexanide; Wound infections