BLOOD CULTURES POSITIVE FOR COAGULASE-NEGATIVE STAPHYLOCOCCI - ANTISEPSIS, PSEUDOBACTEREMIA, AND THERAPY OF PATIENTS

A blood culture cohort study investigating issues related to isolation of coagulase-negative staphylococci (CoNS) and other skin microflora is reported, Data were collected over 12 weeks to determine the incide nce of significant CoNS bacteremia versus that of pseudobacteremia (co ntaminants) and to evaluate drug therapy in patients with cultures pos itive for CoNS, In addition, the effectiveness of 0.2% chlorine peroxi de as a bactericidal disinfectant was compared to that of 10% providon e iodine. A total of 3,276 cultures of blood from 1,433 patients were evaluated in the study. Eighty-nine cultures were positive for skin fl ora, with 81 of 89 (91%) involving CoNS, The incidence of significant CoNS bacteremia was 20 of 81 (24.7%), that of indeterminate bacteremia was 10 of 81 (12.3%), and that of contamination was 59 of 81 (72.8%), The incidence of significant bacteremia involving CoNS was double the 10 to 12% rate based on previous estimations at our institutions, In tests with the two bactericidal disinfectants, 22 of 1,639 cultures (1 .3%) in the chlorine peroxide group versus 37 of 1,637 (2.3%) in the p rovidone iodine group were considered contaminated (P = 0.065). Rates of contamination for venipuncture versus catheter collection were not significantly different (P = 0.46), The overall contamination rate was 59 of 3,276 (1.8%), which is consistent with the lower end of publish ed quality assurance benchmark standards, The low rate was believed to be due to the professional phlebotomy staff in our institutions. Ther e was excellent agreement between retrospective analysis by reviewers, when formal criteria were used, and the attending physicians' intuiti ve clinical impressions in the classification of significant bloodstre am infections (100% agreement) or contamination (95% agreement), Howev er, physicians still used antimicrobial agents to treat nearly one-hal f of the patients with contaminated blood cultures, with vancomycin be ing misused in 34% of patients. In addition, 10% of patients with sign ificant bacteremia were treated with inappropriate agents, There were no significant adverse events or prolonged hospital stays due to the u nnecessary use of vancomycin; however, the additional costs of treatin g patients whose cultures contained CoNS contaminants was estimated to be $1,000 per patient, Measures to limit the unnecessary use of vanco mycin land other agents) are important.