Assessment of multiple coagulase-negative staphylococci isolated in blood cultures using pulsed-field gel electrophoresis

One of the criteria used to determine the clinical importance of coagulase-negative staphylococci (CNS) is the isolation of the bacteria from sequential blood cultures, Sequential isolates of CNS obtained from five immunocompromised patients over three months were genetically characterized by pulsed-field gel electrophoresis (PFGE). This typing method was compared to two first-line typing methods: determination of the species and of antibiotic susceptibility. In four patients the initial clinical evaluation changed because of the PFGE results; several episodes of bacteremia would have been wrongly assessed if only the biotype and the antibiotype had been determined. Pulsed-field gel electrophoresis should therefore be used for CNS strains from immunocompromised patients or those suffering from chronic diseases with non-concordant biotype and antibiotype.