title: Comparison of coagulase-negative staphylococci isolated from blood cultures as a true bacteremia agent and contaminant in terms of slime production and methicillin resistance.
abstract: OBJECTIVE
  The aim of this study is to determine the species distribution, slime activity, and methicillin resistance of coagulase-negative staphylococci (CoNS) isolated from blood cultures as either contaminants or true bacteremia agents.
  
  
  METHODS
  In this study, 13.268 blood culture samples sent to our laboratory from various clinics during a two-year period were examined in terms of the presence of CoNS to clarify whether the isolates are true bacteremia agents, as defined by Centers for Disease Control and Prevention (CDC) criteria. The slime activities of true bacteremia agents (58 CoNS strains) and contaminants (50 randomly selected CoNS strains) were investigated by the Christensen method. The methicillin susceptibilities of the strains were determined by the disk diffusion method.
  
  
  RESULTS
  Although the frequency of slime production was 39.7% among the true bacteremia CoNS agents, it was 18% in CoNS that were judged to be contaminants (p<0.05). S. epidermidis was the most frequently isolated species for both the true bacteremia agent group (56.9%) and contaminant group (74%). Additionally, S. epidermidis was the bacterium most frequently characterized as slime producing in both groups. The methicillin resistance of slime-producing CoNS was determined to be 82.6% for the true bacteremia agent group and 77.8% for the contaminant group.
  
  
  CONCLUSIONS
  The presence of slime activity in CoNS isolated from blood culture samples is supportive evidence that they are most likely the agents of true bacteremia cases.
authors.affiliation: Department of Clinical Microbiology, Ataturk University Faculty of Medicine, Erzurum, Turkey.
authors.forename: Muhammet Hamidullah
authors.initials: MH
authors.lastname: Uyanik
authors.affiliation: Department of Clinical Microbiology, Ataturk University Faculty of Medicine, Erzurum, Turkey.
authors.forename: Halil
authors.initials: H
authors.lastname: Yazgi
authors.affiliation: Department of Infectious Disease, Ataturk University Faculty of Medicine, Erzurum, Turkey.
authors.forename: Kemalettin
authors.initials: K
authors.lastname: Ozden
authors.affiliation: Department of Clinical Microbiology, Ataturk University Faculty of Medicine, Erzurum, Turkey.
authors.forename: Zeynep
authors.initials: Z
authors.lastname: Erdil
authors.affiliation: Department of Clinical Microbiology, Ataturk University Faculty of Medicine, Erzurum, Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Ayyildiz
keywords: True bacteremia; blood culture; coagulase-negative staphylococcus; methicillin resistance; slime production