As the name suggests, bloodstream infections occur when bacterial or fungal infections are present in the blood. Though many types of infection can cause sepsis, bacterial infections cause sepsis most often.3 The most frequently identified pathogens that develop into sepsis include Staphylococcus aureus, Escherichia coli, and some types of Streptococcus.3 With every minute being of the essence when treating patients with suspected or known sepsis, it is critical that healthcare teams be able to streamline the diagnosis of bloodstream infections to provide appropriate care quickly.
A blood culture is a critical step in the management of bloodstream infections, and a positive blood culture either establishes or confirms that there is an infectious etiology for the patient’s illness.4 With definitive microorganism identification sometimes taking several days, clinicians and laboratory professionals need diagnostic solutions that can provide accurate results as quickly as possible to increase the chances of patient survival.
In recent years, there have been significant advances in diagnostic technology, leading to the development of systems that can provide faster, accurate results than those in decades past. One such system is the BACT/ALERT® VIRTUO® fully-automated blood culture system from bioMérieux. With its automated bottle loading and unloading, high thermal stability, and proprietary detection algorithms, VIRTUO has been shown to provide 20% faster time to results on average than a conventional blood culture system, with some organisms detected up to 11 hours faster.5
The volume of blood that is obtained for each blood culture set – which is comprised of an aerobic bottle, for aerobic and facultative anaerobic microorganisms, and an anaerobic bottle, for anaerobic and facultative anaerobic microorganisms – is the most significant variable in recovering microorganisms from patients with bloodstream infections.6 However, it is well understood that blood culture bottles are frequently under-filled, which negatively impacts microorganism recovery. A 2016 review found a wide range of frequencies for under-filled bottles, from 28% to as high as 97.7% of bottles being under-filled.7 To help combat this challenge, the VIRTUO system automatically measures the sample volume for each adult blood culture bottle loaded and provides immediate notification if the bottle is under-filled or over-filled, which supports prompt action by laboratory staff to redraw blood cultures if needed.
Once a blood culture is determined to be positive, laboratory staff take action. Recent studies incorporating newer, advanced diagnostic technologies show clear improvement in a number of outcomes related to both patient care and appropriate antimicrobial usage. One 2015 study looked at what happens after a positive blood culture and compared conventional identification vs. rapid identification (here, the BIOFIRE BCID panel from bioMérieux) vs. rapid identification (again, the BIOFIRE BCID panel) with an antimicrobial stewardship intervention.8 This study found that incorporation of a rapid identification method decreased the treatment of blood culture contaminants and administration of broad-spectrum antimicrobial therapy, while increasing the use of narrow-spectrum antimicrobials. Further, addition of an antimicrobial stewardship intervention shortened the time to appropriate antimicrobial de-escalation or escalation.
In an upcoming webinar on “Streamlining the Diagnosis of Bloodstream Infections in the Age of Technology,” hosted by bioMérieux on March 22, Dr. Rosemary She of Keck Medical Center of USC will discuss the importance of blood cultures and epidemiologic trends in bloodstream infections as they relate to current diagnostic needs. Dr. She will also discuss how enhancements in blood culture systems – and her lab’s experience with VIRTUO – can lead to improved laboratory workflow and support improved patient care.
References
1. Sepsis Fact Sheet. Sepsis Alliance. https://www.sepsis.org/education/resources/fact-sheets/. Published 2020.
2. Kumar A et al. Duration of hypotension before initiation of effective antimicrobial therapy is the critical determinant of survival in human septic shock. Crit Care Med. 2006 Jun;34(6):1589-96.
3. Protect Your Patients from Sepsis. Centers for Disease Control and Prevention. https://www.cdc.gov/sepsis/pdfs/hcp/HCP_infographic_protect-your-patients-from-sepsis-P.pdf.
4. Principles and procedures for Blood Cultures; Approved Guideline, CLSI document M47-A. Clinical and Laboratory Standards Institute (CLSI); Wayne, PA. 2007
5. Altun O, Almuhayawi M, Lüthje P, Taha R, Ullberg M, Özenci V. Controlled Evaluation of the New BacT/Alert Virtuo Blood Culture System for Detection and Time to Detection of Bacteria and Yeasts. J Clin Microbiol. 2016;54(4):1148-1151.
6. Bouza E et al. Is the volume of blood cultured still a significant factor in the diagnosis of bloodstream infections? J Clin Microbiol. 2007;45:2765-2769.
7. Lamy B et al. How to Optimize the Use of Blood Cultures for the Diagnosis of Bloodstream Infections? A State-of-the Art. Front Microbiol. 2016 May 12;7:697.
8. Banerjee R, Teng CB, Cunningham SA, et al. Randomized trial of rapid multiplex polymerase chain reaction-based blood culture identification and susceptibility testing. Clin Infect Dis. 2015;61(7):1071-1080.