Research suggests that approximately 90% of all blood culture tests have negative results.1 That means that for every 1000 blood draws, about 100 patients receive a positive result. But, well-established false positive blood culture rates2 tell us that roughly 30 of the patients who test positive do NOT have a bloodstream infection.
Positive blood culture results are WRONG ≈30% of the time.
Cry Wolf explains the consequences of blood culture contamination.
Just like the boy who cried wolf, high numbers of false positive results cause physicians to question the test, compromising a fast and appropriate response.
Expert clinicians highlight the high cost of false positive blood cultures for both patients and hospitals.
There is a consensus that caregiver compliance with best practices of blood culture collection can reduce false positives blood cultures.
“If emergency nurses really understood all the consequences, compliance would not be an issue.”
Read the Transcript
I certainly became aware of false positives when I was a fellow going through training. Recognizing how every time we were distracted with a false positive, it took away from patients who were truly sick. If there’s a false positive blood culture, that means the patient is subject to potentially unnecessary antibiotic therapy, additional testing that may be unnecessary to figure out where the infection’s coming from rather than focusing on why the patients truly sick and trying to get them better and out the door.
When I was a staff nurse in the emergency department, I really had no awareness of blood culture issues. We drew them and we went on with our day. It was another task that we checked off. It wasn’t until I became an educator that I became aware that, oh, this is a big issue with big consequences.
I never realized that false positives were driving poor patient flow. They’re driving costs up. It’s almost like false positives are this silent vine that just takes over, but nobody really sees it because we’re focused on other things and it’s a huge, huge part of what we have to do every day to lower costs and to lower length of stay.
We realize that we are potentially treating patients who don’t even have a real infection. We’re exposing them to unnecessary antibiotics, increased length of stay and all the complications that go along with that. As our individual organizations have an increasing focus on antimicrobial stewardship and we realized that there are not insignificant quantities of antibiotics used to treat infections that aren’t actually infections and they’re false positives.
A contamination can take a treatment plan in a completely different direction than what the patient actually needs and it disguises a lot of the things that we should be paying attention to.
Some of the dangers patients face when they’re in the hospital for longer than they need to be include, not only C Diff., but MRSA infections, skin breakdown, pulmonary embolism, DVTs. Everything that you get from not moving around and just being in the hospital. You know, just being in the environment itself puts you at risk.
There are articles out there that had been written as early as 1990 about what it’s costing your organization to continue to have these really high contamination rates.
We’re moving toward a world where hospital-acquired infections will not be covered under most insurance plans, and so if a patient develops C Diff. disease during the hospital stay, as a result of unnecessary antibody therapy, then any measures that are taken to treat the patient for that C Diff. infection may not be covered by insurance and so the hospital wouldn’t get reimbursed for that care.
The cost associated with some of these contaminations and some of these extra lengths of stays really falls on the hospital itself, for the most part. If it costs you more to take care of that patient, that’s less reimbursement the hospital will get from that stay. The more complications, the less money that certain payers are providing to the hospital, kind of the pay-for-performance measures.
I think that if emergency nurses really understood all the consequences, compliance would not be an issue.
When educating nurses, especially in the emergency department, they have to see the relevance. If we don’t understand the why, we may take shortcuts that we shouldn’t take. I think the key to the sustainability is accountability. Our Lab has signs that they put up this say, my results are only as good as the specimen you send me, and we weren’t sending them good specimens. We were sending them contaminated specimens and so the results weren’t good. If they understand why they need to do it a certain way and do it well, the consequences downstream, then they’ll do it right.
But what really drives it home is when you tell them why you need to do it this way and I find we get a lot more compliance that way. You tell them why. The nurses always want to know why. It’s about making it part of your culture. It is a culture of safety, a culture of doing what’s right for the patient.
From a patient perspective, I guess I try to think about my mother who is in her seventies and what would this mean to her? You know, every false positive is a story. It’s a person that we’re effecting.
Essentially it comes down to is the patient getting the quality care that they deserve and that they’re seeking. And are we doing everything we can to make sure that they get that. And having those low contamination rates is one of those ways.
What is a false positive blood culture?
1 Zwang O, Albert RK. Analysis of Strategies to Improve Cost Effectiveness of Blood Cultures. J Hosp Med. 2006 Sep;1(5):272-6.
2 Garcia RA, Spitzer ED, Beaudry J, et al. Multidisciplinary team review of best practices for collection and handling of blood cultures to determine effective interventions for increasing the yield of true-positive bacteremia, reducing contamination, and eliminating false-positive central line-associated bloodstream infections. Am J Infect Control. 2015 Nov 1;43(11):1222-37.
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