title: Antibiotic susceptibility testing of grown blood cultures by combining culture and real-time polymerase chain reaction is rapid and effective.
abstract: BACKGROUND
  Early administration of appropriate antibiotic therapy in bacteraemia patients dramatically reduces mortality. A new method for RApid Molecular Antibiotic Susceptibility Testing (RAMAST) that can be applied directly to positive blood cultures was developed and evaluated.
  
  
  RESULTS
  Growth curves and antibiotic susceptibility of blood culture isolates (Staphylococcus aureus, enterococci and (facultative) aerobic gram-negative rods) were determined by incubating diluted blood cultures with and without antibiotics, followed by a quantitative universal 16S PCR to detect the presence or absence of growth. Testing 114 positive blood cultures, RAMAST showed an agreement with microbroth dilution of 96.7% for gram-negative rods, with a minor error (false-susceptibility with a intermediate resistant strain) rate of 1.9%, a major error (false resistance) rate of 0.8% and a very major error (false susceptibility) rate of 0.6%. Agreement for S. aureus was 97.9%, with a very major error rate of 2.1%. Enterococcus species showed 95.0% agreement, with a major error rate of 5.0%. These agreements are comparable with those of the Phoenix system. Starting from a positive blood culture, the test was completed within 9 hours.
  
  
  CONCLUSIONS
  This new rapid method for antibiotic susceptibility testing can potentially provide accurate results for most relevant bacteria commonly isolated from positive blood cultures in less time than routine methods.
authors.affiliation: Department of Medical Microbiology, Care And Public Health Research Institute, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Judith
authors.initials: J
authors.lastname: Beuving
authors.forename: Annelies
authors.initials: A
authors.lastname: Verbon
authors.forename: Firza A
authors.initials: FA
authors.lastname: Gronthoud
authors.forename: Ellen E
authors.initials: EE
authors.lastname: Stobberingh
authors.forename: Petra F G
authors.initials: PF
authors.lastname: Wolffs
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016470:Bacteremia / Q000097:blood*; D001419:Bacteria / Q000187:drug effects* / Q000254:growth & development*; D018929:Cell Culture Techniques / Q000379:methods*; D006801:Humans; D007700:Kinetics; D008826:Microbial Sensitivity Tests / Q000379:methods*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents