Blood culture contamination in the emergency department: An integrative review of strategies to prevent blood culture contamination

Blood culture algorithm implementation in emergency department patients as a diagnostic stewardship intervention

OBJECTIVE

Blood cultures (BCx) are important for selecting appropriate antibiotic treatment. Ordering BCx for conditions with a low probability of bacteremia has limited utility, thus improved guidance for ordering BCx is needed. Inpatient studies have implemented BCx algorithms, but no studies examine the intervention in an Emergency Department (ED) setting.

METHODS

We performed a quasi-experimental pre and postintervention study from January 12, 2020, to October 31, 2023, at a single academic adult ED and implemented a BCx algorithm. The primary outcome was the blood culture event rates (BCE per 100 ED admissions) pre and postintervention. Secondary outcomes included adverse event rates (30-day ED and hospital readmission and antibiotic days of therapy). Seven ED physicians and APP reviewed BCx for appropriateness, with monthly feedback provided to ED leadership and physicians.

RESULTS

After the BCx algorithm implementation, the BCE rate decreased from 12.17 BCE/100 ED admissions to 10.50 BCE/100 ED admissions. Of the 3,478 reviewed BCE, we adjudicated 2,153 BCE (62%) as appropriate, 653 (19%) as inappropriate, and 672 (19%) as uncertain. Adverse safety events were not statistically different pre and postintervention.

CONCLUSIONS

Implementation of an ED BCx algorithm demonstrated a reduction in BCE, without increased adverse safety events. Future studies should compare outcomes of BCx algorithm implementation in a community hospital ED without intensive chart review.

Changing culture: An intervention to improve blood culture quality in the emergency department

OBJECTIVE

Blood cultures (BCs) remain a key investigation in ED patients at risk of bacteraemia. The aim of this study was to assess the effect of a multi-modal, nursing-led intervention to improve the quality of BCs in the ED, in terms of single culture, underfilling and contamination rates.

METHOD

The present study was conducted in the ED of a large urban tertiary referral hospital. The study included four phases: pre-intervention, intervention, post-intervention and sustainability periods. A multi-modal intervention to improve BC quality consisting small group education, posters, brief educational videos, social media presence, quality feedback, small group/individual mentoring and availability of BC collection kits was designed and delivered by two senior ED nurses over 7 weeks. Study data comprised rates of single, underfilled and contaminated cultures in each of three 18-week periods: pre-intervention (baseline), post-intervention and sustainability.

RESULTS

Over the study period 4908 BC sets were collected during 2347 episodes of care in the ED. Single culture sets reduced from 56.2% in the pre-intervention period to 22.8% post-intervention (P < 0.01) and 18.8% in the sustainability period (P < 0.01). Underfilled bottle rates were also significantly reduced (aerobic 52.8% pre-intervention to 19.2% post-intervention, 18.8% sustainability, anaerobic 46.8% pre-intervention to 23.3% post-intervention, 23.8% sustainability). Skin contaminants were grown from 3.7% of BC sets in the pre-intervention period, improving to 1.5% in the post-intervention period (P < 0.001) and 2.1% in the sustainability period (P = 0.03). Total volume of blood cultured was significantly associated with diagnosis of bacteraemia.

CONCLUSION

Significant improvements in BC quality are possible with nursing-based interventions in the ED.

Sites of blood collection and topical disinfectants associated with contaminated cultures: An ambidirectional cohort study

Background

We aimed to determine whether puncture sites for blood sampling and topical disinfectants are associated with rates of contaminated blood cultures in the emergency department (ED) of a single institution.

Methods

This single-center, ambidirectional cohort study of 548 consecutive patients ≥20 years of age was performed in the ED of a university hospital in Japan over a 13-month period. Pairs of blood samples were collected for aerobic and anaerobic cultures from patients in the ED. Physicians selected puncture sites and topical disinfectants according to their personal preference.

Results

Potential contamination was identified in 110 of the 548 patients (20.1%). One hundred fourteen (20.8%) patients showed true-positive results for bacteremia, and 324 (59.1%) patients showed true-negative results. Multivariate analysis revealed more frequent contamination when puncture sites were disinfected with povidone-iodine (PVI) than with alcohol/chlorhexidine (ACHX) (adjusted risk difference, 19.1%; 95% confidence interval [CI]), 15.7-22.6; p < 0.001). In terms of blood collection sites, femoral and central venous (CV) catheter with PVI disinfection showed more frequent contamination than venous sites with ACHX (adjusted risk differences: 26.6%, 95% CI 21.3-31.9, p < 0.001 and 41.1%, 95% CI 22.2-59.9, p < 0.001, respectively).

Conclusion

Rates of contaminated blood cultures were significantly higher when blood was collected from the CV catheter or femoral sites with PVI as the topical disinfectant.

Are bacteria, fungi, and archaea present in the midtrimester amniotic fluid?

OBJECTIVES

This study was conducted to determine whether bacteria, fungi, or archaea are detected in the amniotic fluid of patients who underwent midtrimester amniocentesis for clinical indications.

METHODS

Amniotic fluid samples from 692 pregnancies were tested by using a combination of culture and end-point polymerase chain reaction (PCR) techniques. Intra-amniotic inflammation was defined as an interleukin-6 concentration >2,935 pg/mL.

RESULTS

Microorganisms were detected in 0.3% (2/692) of cases based on cultivation, 1.73% (12/692) based on broad-range end-point PCR, and 2% (14/692) based on the combination of both methods. However, most (13/14) of these cases did not have evidence of intra-amniotic inflammation and delivered at term. Therefore, a positive culture or end-point PCR in most patients appears to have no apparent clinical significance.

CONCLUSIONS

Amniotic fluid in the midtrimester of pregnancy generally does not contain bacteria, fungi, or archaea. Interpretation of amniotic fluid culture and molecular microbiologic results is aided by the assessment of the inflammatory state of the amniotic cavity. The presence of microorganisms, as determined by culture or a microbial signal in the absence of intra-amniotic inflammation, appears to be a benign condition.

Investigation of the selection and use of "other" personal protective equipment to prevent mucous membrane exposure in nurses: A cross-sectional study

BACKGROUND

Selection and use of personal protective equipment (PPE) to prevent non-percutaneous body fluid exposure (NP BFE) is determined by a clinical assessment of risk. The aim of this study was to explore the selection and use of PPE, particularly masks and eye protection to prevent NP BFE, by nurses.

METHODS

This quantitative single-site two-phased study was guided by the Health Belief Model (HBM). Phase 1 was a retrospective electronic database audit of body fluid exposure surveillance data. Phase 2 included a cross-sectional survey.

RESULTS

The highest incidence of reported NP BFE to non-intact skin and mucous membranes during the study period were identified in the emergency department (ED) at 51.3% (20/39), intensive care unit (ICU) at 30.8% (12/39), operating theatre (OT) with 12.9% (5/39), and inpatient renal ward with 5.1% (2/39). Reported PPE use during NP BFE was: 0% face shields or masks, 10% gown/apron, and 15% goggles. Survey results related to Prevention of mucocutaneous exposures were similar across all high-risk units, though ED nurses reported poorer compliance with the use of PPE to prevent exposure. Risk assessment for prevention of NP BFE was reported, yet there was a lack of compliance. The ICU results indicated a positive safety culture in contrast to the ED.

CONCLUSION

The findings are consistent with research identifying inadequate prevention of NP BFE, although nurses are aware of the importance of risk assessment. The HBM has the potential to increase understanding of the differences in nurses' perceptions of risk in safety culture.

Contamination of Blood Cultures From Arterial Catheters and Peripheral Venipuncture in Critically Ill Patients: A Prospective Multicenter Diagnostic Study

BACKGROUND

Collecting blood cultures from indwelling arterial catheters is an attractive option in critically ill adult patients when peripheral venipuncture is difficult. However, whether the contamination proportion of blood cultures from arterial catheters is acceptable compared with that from venipuncture is inconclusive.

RESEARCH QUESTION

Is contamination of blood cultures from arterial catheters noninferior to that from venipuncture in critically ill adult patients with suspected bloodstream infection?

STUDY DESIGN AND METHODS

In this multicenter prospective diagnostic study conducted at five hospitals, we enrolled episodes of paired blood culture collection, each set consisting of blood drawn from an arterial catheter and another by venipuncture, were obtained from critically ill adult patients with cilinical indication. The primary measure was the proportion of contamination, defined as the number of false-positive results relative to the total number of procedures done. The reference standard for true bloodstream infection was blinded assessment by infectious disease specialists. We examined the noninferiority hypothesis that the contamination proportion of blood cultures from arterial catheters did not exceed that from venipuncture by 2.0%.

RESULTS

Of 1,655 episodes of blood culture from December 2018 to July 2021, 590 paired blood culture episodes were enrolled, and 41 of the 590 episodes (6.9%) produced a true bloodstream infection. In blood cultures from arterial catheters, 33 of 590 (6.0%) were positive, and two of 590 (0.3%) were contaminated; in venipuncture, 36 of 590 (6.1%) were positive, and four of 590 (0.7%) were contaminated. The estimated difference in contamination proportion (arterial catheter - venipuncture) was -0.3% (upper limit of one-sided 95% CI, +0.3%). The upper limit of the 95% CI did not exceed the predefined margin of +2.0%, establishing noninferiority (P for noninferiority < .001).

INTERPRETATION

Obtaining blood cultures from arterial catheters is an acceptable alternative to venipuncture in critically ill patients.

CLINICAL TRIAL REGISTRATION

University Hospital Medical Information Network Center (UMIN-CTR); No.: UMIN000035392; URL: https://center6.umin.ac.jp/.

[Optimization of microbial diagnostics by introduction of a blood culture standard operating procedure in the emergency department]

INTRODUCTION

The emergency department (ED) is the main port of entry for patients with infectious diseases, the place where a number of diagnostic procedures are performed and treatment is often initiated. The aim of this retrospective study was to estimate the influence of the establishment and introduction of a blood culture standard operating procedure (BC-SOP) and of the subsequent training of microbial diagnostics in an ED.

METHODS

In a before and after study over a study period of 3 months each (November 2017-January 2018 and November 2018-January 2019), the number of blood cultures taken, the rate of blood cultures per 1000 patients, the number of positive blood cultures and the frequency of typical skin pathogens were evaluated. In the interim time between the two study periods, a BC-SOP was developed in collaboration with the hospital's antibiotic stewardship team and subsequently introduced with staff training in the ED. The study was approved by the local ethics committee of the medical faculty of the Heinrich Heine University (2019-392-RetroDEuA).

RESULTS

In total 92% of the nursing personnel and 93% of the medical personnel received training. The total number of blood cultures increased from 1757 to 2872 (64% increase) and the rate of blood cultures per 1000 patients from 287 to 481 (68% increase). The number of positive blood cultures decreased from 18.6% to 13.7% (p < 0.05). Typical skin pathogens were found in 34.4% and 26.4% of the cases, respectively (p < 0.05).

CONCLUSION

The development, introduction and training of a BC-SOP in the ED can make a relevant contribution to the microbial diagnostics and increase the quantity as well as the quality.