Coagulase-negative Staphylococcus contamination rate before and after switching skin antiseptic for blood cultures from 10% aqueous povidone-iodine to 2% chlorhexidine tincture: a cost-effectiveness analysis

Background: Skin antiseptics are one of the most important factors influencing blood culture contamination rates. We have recently reported the superiority of 2% chlorhexidine tincture over 10% aqueous povidone-iodine in reducing blood culture contamination rate in a two-month study period of prospective study. In our institute, skin antiseptic for blood cultures was thus switched from 10% aqueous povidone-iodine to 2% chlorhexidine tincture since January 1, 2007.

Objective: To compare coagulase-negative Staphylococcus (CoNS) contamination rate before and after switching of skin antiseptic for blood cultures in a longer study period in our institute, King Chulalongkorn Memorial Hospital (KCMH), Bangkok, Thailand. A cost-effective was also analyzed

Methods: CoNS contamination rate before (years 2005 and 2006) and after (years 2007 and 2008) implementation was compared. Venipuncture sites were routinely disinfected by vigorously applying the assigned antiseptic two times, and blood cultures were taken by student, resident, or nurse. An estimate of cost savings between the two periods associated with reduction of CoNS contamination rate including bacterial species identification, a two-day course of vancomycin treatment, and intravenous infusion set, was also calculated.

Results: CoNS contamination rate was decreased from 17.28% (6,162 of 35,657 blood culture samples) to 2.89% (2,642 of 91,342 blood culture samples) before and after switching of skin antiseptic, respectively. The costs of CoNS identification in our laboratory, vancomycin treatment, and infusion set were $5.7, $80, and $4.3 for each patient, respectively. Therefore, an estimate of cost savings associated with our implementation would be $356,670 annually in our institute.

Conclusions: The present study strongly confirms our previous results the superiority of 2% chlorhexidine tincture over 10% aqueous povidone-iodine as skin antiseptic in reducing blood culture contamination rate in a longer study period, leading to save our institute enormous money. We suggest the implementation of 2% chlorhexidine tincture as skin antiseptic for blood cultures as the national guidelines.