THE POSITIVE PREDICTIVE VALUE OF ISOLATING COAGULASE-NEGATIVE STAPHYLOCOCCI FROM BLOOD CULTURES

We used four criteria to define true bloodstream infections after isol ation of coagulase-negative staphylococci (CNS) from Isolator (Wampole Laboratories, Cranbury, NJ) blood cultures: (1) the patient's tempera ture was greater than or equal to 38 degrees C, (2) appropriate treatm ent was administered, (3) the physician diagnosed bloodstream infectio n or criteria for nosocomial bloodstream infection were met, and (4) a t least one clinical sign or laboratory value was consistent with infe ction. Sixty (26.4%) of 227 episodes met these four criteria, By logis tic regression, variables associated with meeting the definition of in fection were admission to a service other than the surgical intensive care unit, the biotype of the Staphylococcus epidermidis isolates, the log of the weighted average of the total number of bacteria per milli liter of blood in all positive cultures, resistance to at least six an timicrobial agents, and the positivity of a BACTEC blood culture speci men that was drawn with the first positive Isolator culture specimen. In a high-risk population, 26% of Isolator blood cultures positive for CNS represented infections, a rate two to four times greater than tha t reported in the literature. Information regarding the species, bioty pe, antibiogram, and number of organisms per milliliter of blood might help physicians distinguish between CNS bloodstream infections and co ntamination.