Reducing Blood Culture Contamination: What Makes the Difference?

Abstract

ISSUE: Blood cultures are widely appreciated by physicians to be among the most important diagnostic tool performed in the diagnosis of serious infections. It is equally recognized that falsely positive results due to contamination can result in inappropriate or delayed treatment, increase lenght of stay and increase cost of health care. Early in 2002, Microbiology Laboratory of the VANJHCS notified the Infection Control staff that the blood contamination rate was high. Retrospective review of blood culture contamination rates from the previous 10 years revealed a gradual increase in the rate. In 1990, there were 217 contaminated sets out of 6,241 blood culture sets(3.5%). In 2001 there were 224 contaminated sets of 3,209 blood culture sets (6.8%) tested. The College of American Pathologist and the American Society for Microbiology had set a goal of 3% blood contamination rate. If the institution has a dedicated Phlebotomy Team the rates are lower. VANJHCS is a teaching hospital with no dedicated Phlebotomy Team. Medical residents and ER nurses were drawing specimens. The medical residents rotation is every month. PROJECT: After review of current literature on the subject, the standard operating procedure (SOP) was revised. In the old SOP, 70% to 90% alcohol was used to cleanse the area followed by 2% iodine or iodophor. The skin de-germing agent at the venipuncture site was changed to 2% Chlorhexidine and 70% Alcohol (Chloraprep One-step applicator) in June 2002. The revised SOP and the blood contamination rate data were used to educate the ER nurses and medical residents. Since medical students rotate monthly, this information was made part of the monthly infection control orientation for residents given by the Infection Control Coordinator. Compliance with hand hygiene and keeping the skin flora out by using meticulous aseptic technique in drawing blood cultures are emphasized in those sessions. To facilitate compliance to the new SOP, each patient unit was provided dedicated containers for blood culture bottles, copies of the SOP, Chloraprep applicators and sterile blood transfer devices. RESULTS: Contamination rate of blood cultures decreased after all the measures mentioned were instituted. Table I . Blood Culture Contamination Rate Year Total # Sets # of sets contaminated BCC Rate (%) 2001 3,299 224 6.8% 2002 3,209 198 6.2% 2003 3,281 140 4.3% 2004 3,256 90 3% 2005 3,248 100 3.1% LESSONS LEARNED: Although progress has been made with those measures, continuous vigilance in staff education and dialogue proved to be the key in increasing awareness of providers to this problem. It is extremely important to continue to monitor and give feedback to the staff regarding results of action taken.