The Clinical Significance of Blood Cultures. Presented BY; Cindy Winfrey, MSN, RN, CIC, DON- LTC TM, VA- BC TM

Transcription

1 The Clinical Significance of Blood Cultures Presented BY; Cindy Winfrey, MSN, RN, CIC, DON- LTC TM, VA- BC TM

2 OVERVIEW Blood cultures are considered an important laboratory tool used to diagnose serious infections. These cultures can potentially become contaminated with organisms from the skin or the environment and may lead to unnecessary treatment of the patient. Therefore, it is important to realize the value of a reliable blood culture.

3 OBJECTIVES Describe the most common bloodstream infection pathogens vs. organisms typically isolated from contaminated culture media. Discuss the impact of contaminated blood cultures to the patient and the hospital Outline the process of blood collection and recognize it s role in blood culture contamination. Describe current methods used to decrease the number of contaminated blood cultures. Understand the importance of proper skin antisepsis in preventing blood culture contamination

4 What is a Blood Culture? Critical tool used to find microorganisms that are spreading through the bloodstream. The bloodstream is normally sterile. Microorganisms found in the blood may be called: Bacteremia: bacteria in blood Fungemia: yeast or fungus in blood Septicemia: blood infection with immune response that can lead to death KK Hall, JA Lyman. Updated Review of Blood Culture Contamination. Clin Micro Review 19(4):Oct p MP Weinstein. Blood Culture Contamination: Persisting Problems and Partial Progress. J Clin Microbiol 41(6): Jun 2003,p Ed. PA Kulich, DL Taylor The Infection Preventionist s Guide to the Lab. APIC/ASM 2012

5 How Does the Blood Become Infected? Present infection in the body Pneumonia Urinary Tract Infection (UTI) Surgical Site Infection (SSI) Direct contamination IV Fluid contamination Intervention directly into the blood IV drug abuse Contaminated instruments Indirect Inoculation IV Catheters Foley Catheters External devices Ed. PA Kulich, DL Taylor The Infection Preventionist s Guide to the Lab. APIC/ASM 2012 LL Steed, W Beardsley. Preventing False Positive Cultures. Oral Presentation, June 2008.

6 IV LINES Invasive Devices Increase the potential for bloodstream infection or contamination URINE CATHETERS

7 Benefit of the Positive Blood Culture Confirm the diagnosis Positive growth detected in bottle Identify the causative organism Gram stain Laboratory identification of organism Provide targeted antibiotic information for treatment Susceptibility report Infection is treated appropriately with less chance of antibiotic resistance. KK Hall, JA Lyman. Updated Rev iew of Blood Culture Contamination. Clin Micro Rev iew 19(4):Oct p MP Weinstein. Blood Culture Contamination: Persisting Problems and Partial Progress. J Clin Microbiol 41(6): Jun 2003, p

8 Pathogens in Bloodstream Infections The most common organisms identified in blood culture and thought to represent a true infection when isolated from a blood culture include the following: Staphylococcus aureus Streptococcus pneumoniae Escherichia coli & other Enterobacteriaceae Pseudomonas aeruginosa Candida albicans KK Hall, JA Lyman. Updated Rev iew of Blood Culture Contamination. Clin Micro Review 19(4):Oct 2006.p MP Weinstein. Blood Culture Contamination: Persisting Problems and Partial Progress. J Clin Microbiol 41(6): Jun 2003,p

9 Contaminated Blood Cultures Organisms that are commonly known as skin or environmental contaminants include: Staphylococcus coagulase negative (SCN) Corynebacterium sp. or diptheroids Bacillus sp. (other than B. anthracis) Propionibacterium acnes Micrococcus sp. Aerococcus sp. Questionable: Viridans group Streptococci sp. Enterococci sp. KK Hall, JA Lyman. Updated Rev iew of Blood Culture Contamination. Clin Micro Review 19(4):Oct p MP Weinstein. Blood Culture Contamination: Persisting Problems and Partial Progress. J Clin Microbiol 41(6): Jun 2003, p

10 Contaminant vrs. Infection Staphylococcus coagulase negative (SCN) is the most frequently seen contaminant in blood cultures. SCN and Streptococcus sp. may cause true infections in patients with intravascular or other implanted devices. The CDC National Hospital Surveillance System (NHSN) uses a defined algorithm to identify true infections, especially from SCN. Multiple sets of blood cultures drawn within two hours apart are recommended to help differentiate between true infection and contamination of these organisms. Clinical relevance of the blood culture may be compromised Microbiology lab results may be held to avoid unnecessary treatment KK Hall, JA Lyman. Updated Rev iew of Blood Culture Contamination. Clin Micro Review 19(4):Oct p MP Weinstein. Blood Culture Contamination: Persisting Problems and Partial Progress. J Clin Microbiol 41(6): Jun 2003, p

11 Consider TIME-TO-POSTIVITY BLOOD CULTURE collection May be used to help determine if central line vascular device is the source of bacteremia: Perform blood collection prior to removing the central line Two blood culture sets are obtained: 1.Peripheral blood culture collected first 2.Blood culture collection obtained from central line within 10 minutes of the peripheral blood culture collection. Same volume of blood must be collected for each access If both blood cultures grow same microorganism and central line draw grows faster ( 2 hours) compared to peripheral draw, then line is assumed the source May help to determine need for central line removal Prevention & Management of CRBSI & CLABSI, VA-BC Study Guide, Association of Vascular Access (2011) p. 111.

12 RECOMMENDED Blood Draw Practice VOLUME Single most important variable in recovering microorganisms from the blood Adults: ml per culture Pediatric Patients: weight adjusted volume & special bottles NUMBER OF CULTURES 2 to 3 blood cultures of at least 20 ml (adults) TIMING OF CULTURE COLLECTION As soon as possible after the onset of fever or chills Before the administration of antibiotic therapy Simultaneous collection can occur if antibiotic therapy is mandated SEPARATE BLOOD DRAWS Can be drawn at the same time Recommend the draws from different sites EJ Baron, et al. Blood Cultures IV. Cumitech 1C ASM Press.

13 False Positive Treatment Outcome Treatment for contaminated blood cultures may result in the following: Prolonged length of stay Increased costs due to unnecessary treatment, estimated to be between $1000-$5000 per day. Lost reimbursement from CMS & other insurer s for preventable healthcare-associated infections, such as CLABSIs. Possible antibiotic resistance due to unnecessary treatment Decreased patient satisfaction scores KK Hall, JA Lyman. Updated Review of Blood Culture Contamination. Clin Micro Review 19(4):Oct p MP Weinstein. Blood Culture Contamination: Persisting Problems and Partial Progress. J Clin Microbiol 41(6): Jun 2003, p

14 Methods to Reduce Contamination Source of the culture Venipuncture blood collection is recommended Catheter draw only as needed Skin preparation (or port/hub disinfection) Follow proper protocol for skin preparation & disinfect port/hub prior to access Culture bottle preparation Bottle tops are not sterile and must be disinfected Bottle inoculation Aseptic transfer must be followed Dedicated phlebotomy teams may improve standardization Use of commercial blood culture kits Education, Training, & Competency S Stohl, et al. Blood cultures at central line insertion in the ICU, a comparison with peripheral venipuncture JClinMicrobiol Apr 2011 MA Marini, et.al. Reducing False-Positive Peripheral Blood Cultures in a Pedatric Emergency Department J Emerg Nurs.May2012 Robert RR. Reducing Blood-Culture Contamination through an Education Program. J Infus Nurs.2011 Jan-Feb;34(1): Thomas S., et al. Impact of a Blood Culture Collection Kit on Blood Culture Sampling Fear & Law of Unintended Consequences. J Hosp Infect 2011 Aug;78(4):256-9.

15 Skin Antisepsis to Prevent Contamination The most common source of contaminated blood cultures is the skin of the patient at the site of collection. Skin antisepsis selection is a key factor in the prevention of blood culture contamination. Utilize a skin antisepsis that provides a significant log reduction of skin flora. Make sure the antiseptic is dry When it s drying, the bugs are dying KK Hall, JA Lyman. Updated Review of Blood Culture Contamination. Clin Micro Review 19(4):Oct p MP Weinstein. Blood Culture Contamination: Persisting Problems and Partial Progress. J Clin Microbiol 41(6): Jun 2003, LL Steed, W Beardsley. Preventing False Positive Cultures. Oral Presentation, June EJ Baron, et al. Blood Cultures IV. Cumitech 1C ASM Press.

16 Process for Peripheral Blood Culture Collection Blood for culture should be collected from a peripheral stick (venipuncture) or a vascular catheter hub/port when necessary Steps used for blood collection: Palpate the vein for access Perform Skin Antisepsis (or hub/port disinfection) Allow product to dry completely Do not wipe, blot, fan, or use any other means to dry the site Disinfect tops of the bottles prior to filling with alcohol pad FINAL

17 Process for Blood Culture Collection Steps continued: Insert collection needle into the vein Never re-palpate or touch the hub/port Blood is typically injected into two bottles of culture media. Aerobic bottle (with oxygen) Anaerobic bottle (without oxygen) Follow manufacturer instructions for bottle collection procedure and recommended volume LL Steed, W Beardsley. Preventing False Positive Cultures. Oral Presentation, June EJ Baron, et al. Blood Cultures IV. Cumitech 1C ASM Press.

18 Access Site Disinfection Is Dependent On: THE ANTISEPTIC AGENT USED THE MICROBIAL BURDEN ON THE SURFACE OF THE ACCESS SITES THE CONCENTRATIO N OF THE ANTISEPTIC AGENT METHOD OF DISINFECTANT APPLICATION THE CONTACT TIME BETWEEN THE SURFACE AND ANTISEPTIC

19 Clinical Guidelines for Skin Antisepsis

20 IV Access Site Disinfection Utilize products that are compatible with IV manufacturer Ensure that disinfection occurs before each access Guidelines suggest seconds scrub prior to each access

21 Summary Proper blood collection practice plays an important role in patient outcomes Contaminated blood cultures can be prevented Performing proper skin antisepsis and intravenous device disinfection prevents contaminants from entering blood culture bottles during collection

22 References KK Hall, JA Lyman. Updated Review of Blood Culture Contamination. Clin Micro Review 19(4):Oct p MP Weinstein. Blood Culture Contamination: Persisting Problems and Partial Progress. J Clin Microbiol 41(6): Jun 2003, p S Stohl, et al. Blood cultures at central line insertion in the ICU, a comparison with peripheral venipuncture J. Clin Microbiol JCN online. Apr LL Steed, W Beardsley. Preventing False Positive Cultures. Oral Presentation, June MA Marini, et.al. Reducing False-Positive Peripheral Blood Cultures in a Pedatric Emergency Department J Emerg Nurs.2012 May 2. Robert RR. Reducing Blood-Culture Contamination through an Education Program. J Infus Nurs.2011 Jan-Feb;34(1): Self WH, et. al. Blood Culture Collection through Peripheral Intravenous Catheters Increases the Risk of Specimen contamination among Adult Emergency Department Patients. ICHE 2012 May;33(5): Lee CC, et. al. The Impact of Overcrowding on the Bacterial Contamination of Blood Cultures in the ED. Am J Emerg Med Dec 12. Thomas S., et al. Impact of a Blood Culture Collection Kit on the Quality of Blood Culture Sampling: Fear & the Law of Unintended Consequences. J Hosp Infect 2011 Aug;78(4): Weddle G., et. al. Reducing Blood Culture Contamination in a Pediatric Emergency Department. Pediatr Emerg Care Mar;27(3): Ed. PA Kulich, DL Taylor The Infection Preventionist s Guide to the Lab. APIC/ASM 2012 EJ Baron, et al. Blood Cultures IV. Cumitech 1C ASM Press. Weinstein, et al. Current Blood Culture Methods and Systems: Clinical Concepts, Technology, and Interpretation of Results Clin Infect Dis. Clinical Practice Guideline: Prevention of Blood Culture Contamination, Emergency Nurse Association, 12/2012:

23 Contact Information Cindy Winfrey, MSN, RN, CIC, DON-LTC TM, VA-BC TM