Comparison of iodophor and alcohol pledgets with the Medi-Flex blood culture prep kit II for preventing contamination of blood cultures

Critical factors in the recovery of pathogenic microorganisms in blood

BACKGROUND

The critical factors for optimal recovery of microbial pathogens from blood are not only the basis for how we perform blood cultures on a daily basis, but are also important for development of all current blood-culture systems. Because much of this research was conducted and published between 1975 and 2010 there is a general sense that many physicians and scientists may not be familiar with it, but it is critical for performing and interpreting blood cultures.

OBJECTIVES

To review the critical factors in the laboratory recovery and isolation of pathogenic microorganisms in blood.

SOURCES

Literature review of published papers, select reviews and updated guidelines.

CONTENT

This review focuses on the critical factors that affect the recovery isolation of pathogenic microorganisms from individuals with bloodstream infections. Contemporary blood-culture systems, and current methods for blood-culture collection, have been designed to incorporate these critical factors so as to optimize recovery and isolation of pathogens while minimizing contamination.

IMPLICATIONS

It is important for microbiologists and practitioners to understand how and why these critical factors affect current blood-culture practices to improve patient management. Future research should emphasize which of these critical factors will still play a role in the era of molecular diagnostic tests, which will no longer be relevant, and which new critical factors have yet to be defined.

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.

Blood Culture Contamination A Randomized Trial Evaluating the Comparative Effectiveness of 3 Skin Antiseptic Interventions

Objective.

To determine relative rates of blood culture contamination for 3 skin antisepsis interventions—10% povidone iodine aqueous solution (PI), 2% iodine tincture (IT), and 2% Chlorhexidine gluconate in 70% isopropyl alcohol (CHG)—when used by dedicated phlebotomy teams to obtain peripheral blood cultures.

Design.

Randomized crossover trial with hospital floor as the unit of randomization.

Setting.

Teaching hospital with 885 beds.

Patients.

All adult patients undergoing peripheral blood culture collection on 3 medical-surgical floors from May 2009 through September 2009.

Intervention.

Each antisepsis intervention was used for 5 months on each study floor, with random crossover after a 1-month washout period. Phlebotomy teams collected all peripheral blood cultures. Each positive blood culture was adjudicated by physicians blinded to the intervention and scored as a true positive or contaminated blood culture. The primary outcome was the rate of blood culture contamination for each antisepsis agent.

Results.

In total, 12,904 peripheral blood culture sets were evaluated, of which 735 (5.7%) were positive. There were 98 contaminated cultures, representing 13.3% of all positive cultures. The overall blood culture contamination rate for the study population was 0.76%. Intent-to-treat rates of contaminated blood cultures were not significantly different among the 3 antiseptics (P= .18), yielding 0.58% with PI (95% confidence interval [CI], 0.38%-0.86%), 0.76% with IT (95% CI, 0.52%-1.07%), and 0.93% with CHG (95% CI, 0.67%-1.27%).

Conclusion.

Choice of antiseptic agent does not impact contamination rates when blood cultures are obtained by a phlebotomy team and should, therefore, be based on costs or preference.

Trial Registration.

ClinicalTrials.gov identifier: NCT01216761.

Effectiveness of practices to reduce blood culture contamination: a Laboratory Medicine Best Practices systematic review and meta-analysis

OBJECTIVES

This article is a systematic review of the effectiveness of three practices for reducing blood culture contamination rates: venipuncture, phlebotomy teams, and prepackaged preparation/collection (prep) kits.

DESIGN AND METHODS

The CDC-funded Laboratory Medicine Best Practices Initiative systematic review methods for quality improvement practices were used.

RESULTS

Studies included as evidence were: 9 venipuncture (vs. versus intravenous catheter), 5 phlebotomy team; and 7 prep kit. All studies for venipuncture and phlebotomy teams favored these practices, with meta-analysis mean odds ratios for venipuncture of 2.69 and phlebotomy teams of 2.58. For prep kits 6 studies' effect sizes were not statistically significantly different from no effect (meta-analysis mean odds ratio 1.12).

CONCLUSIONS

Venipuncture and the use of phlebotomy teams are effective practices for reducing blood culture contamination rates in diverse hospital settings and are recommended as evidence-based "best practices" with high overall strength of evidence and substantial effect size ratings. No recommendation is made for or against prep kits based on uncertain improvement.

Blood cultures: key elements for best practices and future directions

Bloodstream infections (BSI) cause significant morbidity and mortality among populations worldwide. Blood cultures (BCs) are regarded as the "gold standard" for diagnosis of bacteremia and are among the most important functions of the clinical microbiology laboratory. Significant changes in the methods and techniques of obtaining BCs have occurred since the first inception of BCs into clinical practice. Aside from significant improvements of established, conventional technology, new assays for diagnosis of bacteremia and fungemia, particularly those involving molecular techniques, are now available. BCs must be collected under sterile conditions and guidelines for appropriate collection, processing, and results reporting of BCs have been established. This review provides comprehensive information on optimal BC practices for laboratories, utilizing traditional approaches and emerging technology. As laboratories and clinicians must appreciate the key factors affecting the use of these techniques, improved communication between laboratory personnel and clinicians regarding such elements as duration of incubation, workup of contaminants and critical action value reporting will greatly improve the diagnostic approach to BSI.

Isopropyl alcohol compared with isopropyl alcohol plus povidone-iodine as skin preparation for prevention of blood culture contamination

Despite a number of studies on the efficacies of antiseptics for the prevention of blood culture contamination, it still remains unclear which antiseptic should be used. Although the combination of povidone-iodine and isopropyl alcohol has been traditionally used in many institutions, the application of povidone-iodine needs extra time, and there is little evidence that this combination could have an additive effect in reducing contamination rates. To elucidate the additive efficacy of povidone-iodine, we compared two antiseptics, 70% isopropyl alcohol only and 70% isopropyl alcohol plus povidone-iodine, in a prospective, nonrandomized, and partially blinded study in a community hospital in Japan between 1 October 2007 and 21 March 2008. All blood samples for culture were drawn by first-year residents who received formal training on collection techniques. Skin antisepsis was performed with 70% isopropyl alcohol plus povidone-iodine on all inpatient wards and with only 70% isopropyl alcohol in the emergency department. For the group of specimens from inpatient wards cultured, 13 (0.46%) of 2,797 cultures were considered contaminated. For the group of specimens from the emergency department cultured, 12 (0.42%) of 2,856 cultures were considered contaminated. There was no significant difference in the contamination rates between the two groups (relative risk, 0.90; 95% confidence interval, 0.41 to 1.98; P = 0.80). In conclusion, the use of a single application of 70% isopropyl alcohol is a sufficient and a more cost- and time-effective method of obtaining blood samples for culture than the use of a combination of isopropyl alcohol and povidone-iodine. The extremely low contamination rates in both groups suggest that the type of antiseptic used may not be as important as the use of proper technique.

Updated review of blood culture contamination

Blood culture contamination represents an ongoing source of frustration for clinicians and microbiologists alike. Ambiguous culture results often lead to diagnostic uncertainty in clinical management and are associated with increased health care costs due to unnecessary treatment and testing. A variety of strategies have been investigated and employed to decrease contamination rates. In addition, numerous approaches to increase our ability to distinguish between clinically significant bacteremia and contamination have been explored. In recent years, there has been an increase in the application of computer-based tools to support infection control activities as well as provide clinical decision support related to the management of infectious diseases. Finally, new approaches for estimating bacteremia risk which have the potential to decrease unnecessary blood culture utilization have been developed and evaluated. In this review, we provide an overview of blood culture contamination and describe the potential utility of a variety of approaches to improve both detection and prevention. While it is clear that progress is being made, fundamental challenges remain.

Reduction of blood culture contamination rate by an educational intervention

The efficacy of an educational intervention to prevent blood culture contamination (BCC) in internal medicine was studied in two medical wards in a busy tertiary-care hospital in which blood cultures were obtained by physicians rather than dedicated phlebotomists. Baseline BCC rates were 5.7% and 7.1% in intervention and control wards, respectively (p 0.6), compared with 1.95% and 6.7%, respectively, post-intervention (p < 0.001). Following multivariate analysis, only an absence of intervention was an independent variable associated with BCC. Thus simple educational intervention reduced BCC in internal medicine and was considered to be cost-effective.

Skin antisepsis kits containing alcohol and chlorhexidine gluconate or tincture of iodine are associated with low rates of blood culture contamination

OBJECTIVE

Skin preparation is an important factor in reducing the rate of blood culture contamination. We assessed blood culture contamination rates associated with the use of skin antisepsis kits containing either 2% alcoholic chlorhexidine gluconate or 2% alcoholic tincture of iodine.

DESIGN

Prospective, blinded clinical trial.

SETTING

Tertiary-care teaching hospital.

PATIENTS

Adult patients in medical wards, the medical intensive care unit, and the cardiac intensive care unit who needed paired, percutaneous blood cultures.

INTERVENTIONS

House officers, medical students, and healthcare technicians drew the blood for cultures. We prepared sacks containing all of the necessary supplies, including two different types of antiseptic kits. In each sack, one kit contained 2% chlorhexidine in 70% isopropyl alcohol and the other contained 2% tincture of iodine in ethyl alcohol and 70% isopropyl alcohol. Each patient received chlorhexidine at one site and tincture of iodine at the other.

RESULTS

Four (0.9%) of 430 blood culture sets from 215 patients were contaminated. The contamination rate when using alcohol and chlorhexidine (1 of 215, 0.5%) did not differ significantly from the contamination rate when using tincture of iodine (3 of 215, 1.4%; P = .62, McNemar test). There was an 87% probability that the two interventions differed by less than 2% in their rate of contamination.

CONCLUSIONS

Both of these antiseptic kits were highly effective for skin preparation prior to drawing blood for cultures. The use of these kits may have contributed to the low contamination rate observed in this study.