Simple measures to reduce the rate of contamination of blood cultures in Accident and Emergency

Phenotypic and genotypic antibiotic susceptibility profiles of Gram-negative bacteria isolated from bloodstream infections at a referral hospital, Lusaka, Zambia

Bloodstream infections (BSI) caused by antimicrobial-resistant (AMR) Gram-negative bacteria (GNB) are a significant cause of morbidity and mortality. Third-generation cephalosporins (3GCs) have been used as empiric treatment for BSI and other invasive infections for years; however, their overuse could promote the emergence of extended-spectrum beta-lactamases (ESBLs). Thus, this study aimed to determine the epidemiological, clinical and microbiological features and the effects of antimicrobial resistance on the outcomes of BSIs at a referral hospital in Lusaka, Zambia. This was a six-month prospective facility-based study undertaken at a referral hospital in Lusaka, Zambia. As part of the routine diagnosis and patient care, blood samples for bacteriological culture were collected from patients presenting with fever and processed for pathogen identification and antimicrobial susceptibility testing using the VITEK 2 Compact instrument. ESBLs and plasmid-mediated quinolone resistance (PMQR) associated genes were determined using the polymerase chain reaction method. Patient information was collected using a structured data collection sheet and entered in CSpro 7.6. Data were analysed in WHOnet and STATA version 14. A total of 88 GNB were isolated, of which 76% were Enterobacterales, 14% Acinetobacter baumannii and 8% Pseudomonas aeruginosa. Resistance to third and fourth-generation cephalosporins was 75% and 32%, respectively. Noteworthy was the high prevalence (68%) of inappropriate empirical treatment, carbapenem resistance (7%), multi-drug resistance (83%) and ESBL-producers (76%). In comparison to E. coli as a causative agent of BSI, the odds of death were significantly higher among patients infected with Acinetobacter baumannii (OR = 3.8). The odds of death were also higher in patients that received 3GCs as empiric treatment than in those that received 4GCs or other (none cephalosporin) treatment options. Structured surveillance, yearly antibiogram updates, improved infection control and a well functional antimicrobial stewardship (AMS) program, are of utmost importance in improving appropriate antimicrobial treatment selection and favourable patient outcomes.

Patient-specific risk factors contributing to blood culture contamination

Objective:

Contaminated blood cultures result in extended hospital stays and unnecessary antibiotic therapy. Patient-specific factors associated with blood culture contamination remain largely unexplored. Identifying patients at higher risk of blood culture contamination could alert healthcare providers to take extra precautionary measures to limit contamination in these patients, and thereby prevent associated adverse outcomes. We sought to identify patient-related factors that contribute to blood culture contamination in hospitalized patients.

Design and setting:

We conducted a secondary data analysis of a retrospective cohort study at an academic medical center.

Patients:

Study participants included 19,255 adult patients who had blood culture(s) performed during a hospital admission between June 2014 and December 2016.

Methods:

Data were analyzed to evaluate risk factors for blood culture contamination using logistic regression.

Results:

Among adult patients, we identified 464 contaminated episodes and 11,010 negative blood-culture episodes. Chronic obstructive pulmonary disease (adjusted odds ratio [AOR], 1.67; 95% confidence interval [CI], 1.20–2.34) and stay in an intensive care unit (ICU) during an admission (AOR, 1.41; 95% CI, 1.14–1.74) were associated with blood culture contamination. Other risk factors included race, body mass index, and admission from the emergency department. Subgroup analyses of patients admitted from the emergency department showed similar results.

Conclusions:

We identified patient-specific factors that increase the odds of false-positive blood cultures. By introducing mitigation strategies to limit contamination in patients with these risk factors, it may be possible to reduce the adverse clinical impact of blood culture contamination.

Initial Specimen Diversion Device® Reduces Blood Culture Contamination and Vancomycin Use in Academic Medical Center

BACKGROUND

In suspected bloodstream infections, accurate blood culture results are critical to timely diagnoses and appropriate antibiotic administration.

AIM

An Initial Specimen Diversion Device®, Steripath®, (Magnolia Medical Technologies, Seattle, WA) was evaluated for efficacy in reducing blood culture contamination at Brooke Army Medical Center (6.8% six-month contamination rate prior to intervention) in a six-month quality improvement project.

METHODS

Blood cultures in the emergency department were collected using either Steripath® or the standard method. 20 mL of blood was cultured into an aerobic and anaerobic medium and incubated for five days using an automated microbial detection system immediately after collection. Positive bottles were Gram stained and plated. Rapid molecular PCR identification was performed on all first positive bottles within a blood culture set for each admission or ED visit. Speciation was deduced during antimicrobial sensitivity testing using the Vitek-2 instrument.

FINDINGS

Seven (7/1016, 0.69%) contamination events occurred when using Steripath® vs. 53 (53/800, 6.6%) contamination events when using the standard method. Steripath® use was associated with a 90% lower incidence of blood culture contamination vs. the standard method. Post-study, Steripath® use was implemented as standard practice hospital-wide, and a retrospective data analysis attributed a 31.4% decrease in vancomycin days of therapy to Steripath® adoption.

CONCLUSION

Using Steripath® significantly decreased blood culture contamination events for bacterial bloodstream infections compared to the standard method. Subsequent adoption of Steripath® reduced overall vancomycin usage. With widescale implementation Steripath® could bolster antibiotic stewardship, mitigating antibiotic resistance caused by unnecessary antibacterial treatments.

Practical Guidance for Clinical Microbiology Laboratories: A Comprehensive Update on the Problem of Blood Culture Contamination and a Discussion of Methods for Addressing the Problem

In this review, we present a comprehensive discussion of matters related to the problem of blood culture contamination. Issues addressed include the scope and magnitude of the problem, the bacteria most often recognized as contaminants, the impact of blood culture contamination on clinical microbiology laboratory function, the economic and clinical ramifications of contamination, and, perhaps most importantly, a systematic discussion of solutions to the problem. We conclude by providing a series of unanswered questions that pertain to this important issue.

Successful Reduction of Blood Culture Contamination in an Emergency Department by Monitoring and Feedback

Background:

Blood Culture (BC) contamination is a common problem in the Emergency Department (ED) and is associated with prolonged length of patient stay and excess costs.

Objective:

The study aimed to investigate the impact of monthly monitoring and feedback of BC results on contamination rates.

Methods:

Data from a previous study showed that the contamination rate in the ED consistently exceeded the recommended level. This triggered an ad hoc Quality Improvement team to develop and implement a corrective action plan. In 2017, BC contamination rates were reported to the ED on a monthly basis. In response to this, ED staff conducted intensified educational workshops, followed by private counselling and competency assessment of nurses who collected contaminated BCs.

Results:

A total of 12 educational workshops were conducted in February and March, 2017. The intervention resulted in >60% reduction in the contamination rate, from 8.6% baseline level to less than 3%. Of the 2660 BC sets drawn in 2017 from 1318 patients, 128 (4.8%) were contaminated, accounting for 39.5% of the total number of positive cultures. Sixty percent of the contaminated BCs grew Coagulase-negativeStaphylococcusspecies; other contaminants includedCorynebacteriumspp.,Micrococcusspp.,Propionibacteriumspp.,viridansStreptococcus, andNeisseriaspp.

Conclusion:

Continuous monitoring and feedback of contamination rates reduced BC contamination.

Diversion Principle Reduces Skin Flora Contamination Rates in a Community Hospital

CONTEXT.—

Blood culture contamination is a common problem faced by medical centers and leads to significant cost. A possible method to reduce contamination is to discard the initial aliquot of blood, which contains skin and bacteria.

OBJECTIVE.—

To determine whether the rate of contaminant blood cultures could be reduced by changing the order of draw to divert the first 7 mL to a gold- or green-top tube.

DESIGN.—

A preintervention and postintervention study was conducted. During the 18-month intervention phase (September 2015-February 2017), all nurses in the emergency department and inpatient floor phlebotomists collected blood cultures by drawing the first 7 mL of blood into a gold- or green-top tube followed by drawing blood for blood culture bottles. The 18 months immediately preceding the study period (February 2014-July 2015) were used for comparison.

RESULTS.—

There was an overall statistically significant decrease in contamination rate from 2.46% in the prediversion protocol group to 1.70% in the postdiversion protocol group (P < .001). Emergency department drawn cultures and inpatient cultures showed significant decrease in contamination rates between the preprotocol and postprotocol groups, 2.92% versus 1.95% (P < .001) for emergency department, and 1.82% versus 1.31% (P = .03) for inpatient. We noted less month-to-month variation during the study period compared with the preintervention period.

CONCLUSIONS.—

By using this simple diversion method, we were able to improve blood culture contamination rates for our emergency department and inpatients while incurring no added cost to the procedure.

Decreasing Blood Culture Contaminants in a Pediatric Emergency Department: An Interrupted Time Series Analysis

INTRODUCTION

High peripheral blood culture contamination rates (BCCR) in the emergency department (ED) contribute to overuse and harm. This study describes 2 years of quality improvement (QI) interventions that aimed to decrease a high BCCR in a pediatric ED.

METHODS

The QI team created a Key Driver Diagram with multiple Plan-Do-Study-Act (PDSA) cycles. PDSA interventions included a venipuncture sterility checklist (PDSA1), phlebotomist feedback system (PDSA2), and physician ordering guidelines (PDSA3). The specific aim was to decrease the BCCR by 50% within 24 months. The secondary aim was to decrease the peripheral blood culture ordering rate (BCOR) by 10% within 24 months. The balancing measure was the proportion of pathogenic bacteremia cases at ED return visits before and after PDSA3 implementation. A financial measure estimated the savings in charges between the observed and expected contaminants in PDSA3. An interrupted time series design applied statistical process control methodology to detect special cause variations.

RESULTS

The BCCR in the baseline, PDSA1, PDSA2, and PDSA3 periods were 3.02%, 2.30%, 1.58%, and 1.17%, respectively. The BCOR in the baseline, PDSA1, PDSA2, and PDSA3 periods was 4.80%, 4.26%, 3.82%, and 3.49%, respectively. Special cause variations occurred after PDSA cycle implementations for both BCCR and BCOR. There was no change in the balancing measure. The interventions were associated with an annual prevention of 95 contaminants and savings of $300,070.

CONCLUSIONS

Interventions that focused on improving venipuncture technique and limiting unnecessary blood cultures were associated with fewer contaminants and the achievement of the QI team's project aims.

Adverse Economic Impact Associated With Blood Culture Contamination in a Pediatric Emergency Department

BACKGROUND

Blood culture contamination (BCC) leads to unnecessary interventions including hospitalization, antibiotic administration and additional laboratory tests. Previous studies in adults revealed that BCC was associated with unnecessary financial expenditures. However, information pertaining to the pediatric population is limited. Therefore, we investigated the details of the adverse economic impact associated with BCC in a pediatric emergency department (ED) in Japan.

METHODS

This study was a retrospective, observational study. We collected data on blood cultures performed in patients 18 years of age in a pediatric ED. Medical records of patients with positive blood cultures were reviewed, and the information regarding adverse events related to BCC was extracted. Medical costs related to BCC were estimated from the data.

RESULTS

In total, 13,139 sets of blood cultures were performed from April 2013 to June 2016, and 141 cases (1.1%) of BCC were identified. Among these, 106 patients (75%) experienced at least 1 adverse event associated with BCC. The total medical cost due to BCC was 4,076,713 Japanese yen. Multifaceted approaches targeting ED physicians including lectures on optimal blood collection methods and monthly feedback on BCC rates were effective in reducing the BCC rate and its related costs.

CONCLUSIONS

Interventions associated with BCC were common and accounted for significant adverse economic impact on pediatric patients. Regular education and monitoring were effective in reducing BCC and its related costs.

Multidisciplinary team review of best practices for collection and handling of blood cultures to determine effective interventions for increasing the yield of true-positive bacteremias, reducing contamination, and eliminating false-positive central line-associated bloodstream infections

BACKGROUND

A literature search was conducted using keywords for articles published in English from January 1990 to March 2015. Using criteria related to blood culture collection and handling, the search yielded 101 articles. References used also included Microbiology Laboratory standards, guidelines, and textbook information.

RESULTS

The literature identified diverse and complex issues surrounding blood culture practices, including the impact of false-positive results, laboratory definition of contamination, effect on central line-associated bloodstream infection (CLABSI) reporting, indications for collecting blood cultures, drawing from venipuncture sites versus intravascular catheters, selection of antiseptics, use of needleless connectors, inoculation of blood culture bottles, and optimizing program management in emergency departments, education, and implementation of bundled practice initiatives.

CONCLUSION

Hospitals should optimize best practice in the collection, handling, and management of blood culture specimens, an often overlooked but essential component in providing optimal care of patients in all settings and populations, reducing financial burdens, and increasing the accuracy of reportable CLABSI. Although universal concepts exist in blood culture practices, some issues require further research to determine benefit. Institutions undertaking a review of their blood culture programs are encouraged to use a checklist that addresses elements that encompass the research contained in this review.

Factors Associated with Blood Culture Contamination in the Emergency Department: Critical Illness, End-Stage Renal Disease, and Old Age

Background

Blood culture contamination in emergency departments (ED) that experience a high volume of patients has negative impacts on optimal patient care. It is therefore important to identify risk factors associated with blood culture contamination in EDs.

Methodology/Principal Findings

A prospectively observational study in a university-affiliated hospital were conducted between August 2011 and December 2012. Positive monomicrobial and negative blood cultures drawn from adult patients in the ED were analyzed to evaluate the possible risk factors for contamination. A total of 1,148 positive monomicrobial cases, 391 contamination cases, and 13,689 cases of negative blood culture were identified. Compared to patients with negative blood cultures, patients in triage levels 1 and 2 (Incidence Rate Ratio, IRR = 2.24), patients with end-stage renal disease (ESRD) (IRR = 2.05), and older patients (IRR: 1.02 per year) were more likely to be associated with ED blood culture contamination.

Conclusions/Significance

Critical patients (triage levels 1 and 2), ESRD patients, and older patients were more commonly associated with blood culture contamination in the ED. Further studies to evaluate whether the characteristics of skin commensals contribute to blood culture contamination is warranted, especially in hospitals populated with high-risk patients.

Correlation between mass and volume of collected blood with positivity of blood cultures

BACKGROUND

The collection of blood cultures is an extremely important method in the management of patients with suspected infection. Microbiology laboratories should monitor blood culture collection.

METHODS

Over an 8-month period we developed a prospective, observational study in an adult Intensive Care Unit (ICU). We correlated the mass contained in the blood vials with blood culture positivity and we also verified the relationship between the mass of blood and blood volume collected for the diagnosis of bloodstream infection (BSI), as well as we explored factors predicting positive blood cultures.

RESULTS

We evaluated 345 patients with sepsis, severe sepsis or septic shock for whom blood culture bottles were collected for the diagnosis of BSI. Of the 55 patients with BSI, 40.0% had peripheral blood culture collection only. BSIs were classified as nosocomial in 34.5%. In the multivariate model, the blood culture mass (in grams) remained a significant predictor of positivity, with an odds ratio 1.01 (i.e., for each additional 1 mL of blood collected there was a 1% increase in positivity; 95% CI 1.01-1.02, p = 0.001; Nagelkerke R Square [R(2)] = 0.192). For blood volume collected, the adjusted odds ratio was estimated at 1.02 (95% CI: 1.01-1.03, p < 0.001; R(2) = 0.199). For each set of collected blood cultures beyond one set, the adjusted odds ratio was estimated to be 1.27 (95% CI: 1.14-1.41, p < 0.001; R(2) = 0.221).

CONCLUSIONS

Our study was a quality improvement project that showed that microbiology laboratories can use the weight of blood culture bottles to determine if appropriate volume has been collected to improve the diagnosis of BSI.

Blood culture contamination rate in an intensive care setting: Effectiveness of an education-based intervention

BACKGROUND

Blood culture (BC) contamination rate is an indicator of quality of care scarcely explored in intensive care units (ICUs). We analyzed the BC contamination rate in our ICU to assess the effectiveness of an education-based intervention.

METHODS

We conducted an interventional study with concurrent controls. Consecutive BCs drawn during a 6-month period were included. An education-based intervention was presented to case nurses (optimal technique). The remaining nurses comprised the control group (standard technique). Two independent observers assessed clinical significance of saprophytic skin bacteria isolated in BCs.

RESULTS

Six hundred fifty-six BCs were obtained: 308 (47%) via optimal technique and 348 (53%) via standard technique (47%). One hundred eighty-seven BCs were positive for saprophytic microorganisms; 127 (89%) were considered unrelated to infection. Coagulase-negative staphylococci isolation was lower in the optimal technique group (14% vs 26%; P < .001), as well as contamination due to coagulase-negative staphylococci (12% vs 21%; P = .002) or Acinetobacter baumannii (0.3% vs 2%; P = .013). BC contamination rate was 13% in the optimal technique group versus 23% in the standard group (P < .005). In the optimal technique group, BC contamination rate was higher in BCs drawn through the catheter (17% vs 7%; P = .028).

CONCLUSIONS

An education-based intervention significantly reduced the BC contamination rate in our ICU. It seems necessary to design a tool to extract BCs through the catheter to minimize the risk of contamination.

The effect of a quality improvement programme reducing blood culture contamination on the detection of bloodstream infection in an emergency department

BACKGROUND

Contaminated blood cultures (BC) generate avoidable costs and prolong hospital stays. To measure our hospital's performance against the recommended standard of <3% BC contamination, we performed a prospective study.

METHODS

We prospectively determined the frequency of contaminated and genuinely positive BC hospital-wide over seven months.

RESULTS

Overall, 73 of 1,829 blood cultures reviewed were contaminated (4.0%). However, distribution of contamination was not uniform. Finding a consistently higher incidence of contamination (11.7%) in our emergency department (ED) than elsewhere in the hospital (2.5%), we adopted a collaborative quality improvement strategy targeted to the ED. A combination of education, modified BC packs and regular feedback of BC results was associated with a significant reduction in contamination (7.4%, p=0.01) over the next six months. Our data suggests that contaminated BC were more likely to have been taken during regular day time hours (odds ratio (OR) 2.7, p=0.012), rather than overnight and were not associated with influxes of new junior medical staff. We found no evidence that the incidence of true bloodstream infection (12.8%) diagnosed by our ED was adversely affected by our intervention (10.7%, p=0.35).

CONCLUSIONS

Using a simple and inexpensive collaborative intervention we reduced BC contamination without adversely affecting the detection of genuine BSI.

Cost analysis of strategies to reduce blood culture contamination in the emergency department: sterile collection kits and phlebotomy teams

OBJECTIVE

Blood culture collection practices that reduce contamination, such as sterile blood culture collection kits and phlebotomy teams, increase up-front costs for collecting cultures but may lead to net savings by eliminating downstream costs associated with contamination. The study objective was to compare overall hospital costs associated with 3 collection strategies: usual care, sterile kits, and phlebotomy teams.

DESIGN

Cost analysis.

SETTING

This analysis was conducted from the perspective of a hospital leadership team selecting a blood culture collection strategy for an adult emergency department (ED) with 8,000 cultures drawn annually.

METHODS

Total hospital costs associated with 3 strategies were compared: (1) usual care, with nurses collecting cultures without a standardized protocol; (2) sterile kits, with nurses using a dedicated sterile collection kit; and (3) phlebotomy teams, with cultures collected by laboratory-based phlebotomists. In the base case, contamination rates associated with usual care, sterile kits, and phlebotomy teams were assumed to be 4.34%, 1.68%, and 1.10%, respectively. Total hospital costs included costs of collecting cultures and hospitalization costs according to culture results (negative, true positive, and contaminated).

RESULTS

Compared with usual care, annual net savings using the sterile kit and phlebotomy team strategies were $483,219 and $288,980, respectively. Both strategies remained less costly than usual care across a broad range of sensitivity analyses.

CONCLUSIONS

EDs with high blood culture contamination rates should strongly consider evidence-based strategies to reduce contamination. In addition to improving quality, implementing a sterile collection kit or phlebotomy team strategy is likely to result in net cost savings.

Reducing blood culture contamination in the emergency department: an interrupted time series quality improvement study

OBJECTIVES

Blood culture contamination is a common problem in the emergency department (ED) that leads to unnecessary patient morbidity and health care costs. The study objective was to develop and evaluate the effectiveness of a quality improvement (QI) intervention for reducing blood culture contamination in an ED.

METHODS

The authors developed a QI intervention to reduce blood culture contamination in the ED and then evaluated its effectiveness in a prospective interrupted times series study. The QI intervention involved changing the technique of blood culture specimen collection from the traditional clean procedure to a new sterile procedure, with standardized use of sterile gloves and a new materials kit containing a 2% chlorhexidine skin antisepsis device, a sterile fenestrated drape, a sterile needle, and a procedural checklist. The intervention was implemented in a university-affiliated ED and its effect on blood culture contamination evaluated by comparing the biweekly percentages of blood cultures contaminated during a 48-week baseline period (clean technique) and 48-week intervention period (sterile technique), using segmented regression analysis with adjustment for secular trends and first-order autocorrelation. The goal was to achieve and maintain a contamination rate below 3%.

RESULTS

During the baseline period, 321 of 7,389 (4.3%) cultures were contaminated, compared to 111 of 6,590 (1.7%) during the intervention period (p < 0.001). In the segmented regression model, the intervention was associated with an immediate 2.9% (95% confidence interval [CI] = 2.2% to 3.2%) absolute reduction in contamination. The contamination rate was maintained below 3% during each biweekly interval throughout the intervention period.

CONCLUSIONS

A QI assessment of ED blood culture contamination led to development of a targeted intervention to convert the process of blood culture collection from a clean to a fully sterile procedure. Implementation of this intervention led to an immediate and sustained reduction of contamination in an ED with a high baseline contamination rate.

Blood sample collection and patient identification demand improvement: a questionnaire study of preanalytical practices in hospital wards and laboratories

Scand J Caring Sci; 2010; 24; 581-591 
 Blood sample collection and patient identification demand improvement: a questionnaire study of preanalytical practices in hospital wards and laboratories

BACKGROUND

  Most errors in venous blood testing result from human mistakes occurring before the sample reach the laboratory.

AIMS

  To survey venous blood sampling (VBS) practices in hospital wards and to compare practices with hospital laboratories.

METHODS

  Staff in two hospitals (all wards) and two hospital laboratories (314 respondents, response rate 94%), completed a questionnaire addressing issues relevant to the collection of venous blood samples for clinical chemistry testing.

RESULTS

  The findings suggest that instructions for patient identification and the collection of venous blood samples were not always followed. For example, 79% of the respondents reported the undesirable practice (UDP) of not always using wristbands for patient identification. Similarly, 87% of the respondents noted the UDP of removing venous stasis after the sampling is finished. Compared with the ward staff, a significantly higher proportion of the laboratory staff reported desirable practices regarding the collection of venous blood samples. Neither education nor the existence of established sampling routines was clearly associated with VBS practices among the ward staff.

CONCLUSIONS

  The results of this study, the first of its kind, suggest that a clinically important risk of error is associated with VBS in the surveyed wards. Most important is the risk of misidentification of patients. Quality improvement of blood sample collection is clearly needed, particularly in hospital wards.

Skin antiseptics in venous puncture-site disinfection for prevention of blood culture contamination: systematic review with meta-analysis

Blood cultures drawn by venous puncture are common clinical procedures for the detection of bacteraemia. Blood culture contamination (BCC) can lead to clinical misinterpretation and unnecessary expenses. We aimed to systematically review randomised controlled trials (RCTs) with skin antiseptics for prevention of contamination in venous-puncture drawn blood cultures. We conducted database search using CENTRAL (Cochrane Library issue April 2010), MEDLINE, EMBASE and mRCT, in June 2010. All RCTs testing skin antiseptics in venous-puncture drawn blood cultures were retrieved. Relative risk (RR) of the BCC outcome was analysed by random effects method using confidence interval (CI) of 95%. Studies were assessed by one review author and checked by another. Six studies were identified. Single-trial comparisons showed that alcoholic iodine tincture was better than non-alcoholic povidone-iodine, and isopropyl/acetone/povidone-iodine showed superiority against isopropyl/povidone-iodine. Meta-analysis demonstrated that alcoholic chlorhexidine was better than non-alcoholic povidone-iodine (RR: 0.33; 95% CI: 0.24-0.46) in 4757 blood cultures from two trials. Alcoholic solutions were better than non-alcoholic products (0.53; 0.31-0.90) in 21,300 blood cultures from four studies. Two trials with 13,418 blood cultures showed that iodine tincture was not superior to povidone-iodine in BCC prevention (0.79; 0.54-1.18). Alcoholic iodine was not different from non-alcoholic iodine (0.79; 0.53-1.17). Comparison of chlorhexidine vs iodine compounds was not conclusive. Alcohol alone was not inferior to iodinated products for prevention of contamination in venous-puncture drawn blood cultures. The association of alcohol and povidone-iodine did not seem to be useful. Alcoholic chlorhexidine solutions reduced blood culture false positives compared with aqueous povidone-iodine.

Blood cultures: towards zero false positives

The culture of micro-organisms from blood is an essential laboratory test for the diagnosis of bacteraemia. Early positive results provide valuable diagnostic information on which appropriate antimicrobial therapy can be initiated. Like any tests, however, false-positive blood culture results can limit the utility of this important tool. These false-positive results arise due to contamination. Reports from NHS trusts and equipment suppliers suggest these contamination rates could be as high as 10% (Department of Health (DH), 2007). A variety of strategies have been investigated and employed to decrease contamination rates. This article describes the utility of a variety of approaches to reduce the number of false-positive percutaneous blood cultures specifically in the adult population.

Impact of blood cultures drawn by phlebotomy on contamination rates and health care costs in a hospital emergency department

We conducted a prospective comparison of blood culture contamination rates associated with dedicated phlebotomists and nonphlebotomy staff in the emergency department (ED) at Parkland Memorial Hospital in Dallas, TX. In addition, hospital charges and lengths of stay were determined for patients with negative, false-positive, and true-positive blood culture results. A total of 5,432 blood culture collections from two ED areas, the western wing of the ED (ED west) and the nonwestern wing of the ED (ED nonwest), were evaluated over a 13-month period. Phlebotomists drew 2,012 (55%) of the blood cultures in ED west while nonphlebotomy staff drew 1,650 (45%) in ED west and 1,770 (100%) in ED nonwest. The contamination rates of blood cultures collected by phlebotomists were significantly lower than those collected by nonphlebotomists in ED west (62/2,012 [3.1%] versus 122/1,650 [7.4%]; P < 0.001). Similar results were observed when rates between phlebotomists in ED west and nonphlebotomy staff in ED nonwest were compared (62/2,012 [3.1%] versus 100/1,770 [5.6%]; P < 0.001). Comparison of median patient charges between negative and false-positive episodes ($18,752 versus $27,472) showed $8,720 in additional charges per contamination event while the median length of stay increased marginally from 4 to 5 days. By utilizing phlebotomists to collect blood cultures in the ED, contamination rates were lowered to recommended levels, with projected reductions in patient charges of approximately $4.1 million per year.

Peripheral blood culture contamination in adults and venepuncture technique: prospective cohort study

Aims:

To test the hypothesis that compliance with a hospital protocol on peripheral blood culture (PBC) collection in adults is associated with a reduction in PBC contamination, and to investigate likely contributing factors for contamination.

Methods:

A prospective cohort study was conducted, utilising data collection by participant questionnaire completion, and utilising bacteriology laboratory results on PBCs. Participants were all healthcare workers involved in obtaining PBCs from adults.

Results:

1460 PBCs with questionnaires were received. Contamination among the 1460 PBCs as a whole was 8.8%. 766 of the questionnaires were sufficiently complete to allow analysis of blood culture contamination in relation to protocol compliance. Among these, protocol compliance was 30% and contamination was 8.0%. When the protocol was complied with, 2.6% of PBCs were contaminated, but when the protocol was not followed, contamination was significantly higher at 10.3% (OR 4.35, 95% CI 1.84 to 12.54). Univariate analysis on all 1460 PBCs suggested that the site for blood collection, and disinfection of the venepuncture site were important factors in PBC contamination: when no venepuncture site disinfection was performed, contamination was significantly higher than when alcohol was used (5.1% versus 15.8%, OR 3.46, 95% CI 2.01 to 5.97); when a PBC collection site other than a fresh peripheral vein was used, contamination was significantly higher (7.3% versus 12.0%, OR 1.75, 95% CI 1.03 to 2.96).

Conclusions:

Compliance with a hospital protocol on PBC collection technique in adults significantly reduces blood culture contamination.