False-positive immunochromatographic CTX-M enzyme test from direct testing of a positive blood culture

Abstract Introduction/Objective Blood cultures are commonly obtained to evaluate the presence of bacteria or fungal infection in a patient’s bloodstream. The presence of living microorganisms circulating in the bloodstream is of substantial prognostic and diagnostic importance. A positive blood culture indicates a reason for the patient’s illness and provides the etiological agent for antimicrobial therapy. Collection of blood culture is an exact process that requires time, the proper order of draw, and following of correct protocol. The busy Emergency department that requires multiple demands for nurse’s time, turnover of staff, rushing from one task to another can result in the improper collection and false-positive blood cultures. The national benchmark is set at 3% by the American Society of Clinical Microbiology (ASM) and The Clinical and Laboratory Standard Institute (CLSI). False-positive blood culture results in increased length of stay and unnecessary antimicrobial therapy, resulting in an increased cost burden to the hospital of about $5000 per patient. Methods/Case Report At our 150-bed community hospital, 26 beds Emergency Department, we have come a long way in reduction of our blood culture contamination rates from upwards of 4% to less than 2%, far lower than the national benchmark. Results (if a Case Study enter NA) NA Conclusion There are multiple devices available from various manufacturers claiming to reduce blood culture contamination. These devices do reduce blood culture (BC) contamination but at an added cost of the device. The rate of BC can be reduced and less than 3% is achievable by materials available in the laboratory. We have achieved this by providing training to every new staff by demonstration and direct observation, providing everything required for collection in a kit, using proper technique, the inclusion of diversion method that involves the aseptic collection of a clear tube before collecting blood cultures, and following up monthly on any false positive blood cultures.

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LO47: Use of C-reactive protein can safely decrease the number of emergency department patients with sepsis who require blood cultures

CJEM ◽

10.1017/cem.2017.109 ◽

2017 ◽

Vol 19 (S1) ◽

pp. S44

Author(s):

R. Stenstrom ◽

J. Choi ◽

E. Grafstein ◽

T. Kawano ◽

D. Sweet ◽

...

Keyword(s):

Emergency Department ◽

Blood Culture ◽

Positive Blood Culture ◽

False Positive ◽

Blood Cultures ◽

Low Risk ◽

Reactive Protein ◽

Emergency Department Patients ◽

Multicenter Prospective Cohort Study ◽

Multicenter Prospective Cohort

Introduction: Sepsis protocols call for the acquisition of blood cultures in septic emergency department (ED) patients.However, the criteria for blood cultures are vague, they are costly, only positive 8-12% of the time, with up to half of these being false positives. The objective of this study was to establish if positive blood cultures could be excluded in low-risk sepsis patients with levels of CRP below 20 ml/L. Methods: This was a multicenter prospective cohort study of 765 ED patients at St Paul’s and Mount St Joseph’s hospitals in Vancouver with sepsis (2 or more SIRS criteria and infection) and none of: immuncompromised, injection drug use, indwelling vascular device or septic shock (SBP<90 mmhg). Consecutive patients with sepsis had CRP and blood cultures obtained at the same time.OUTCOMES. True positive blood cultures, false positive blood cultures, positive blood cultures that changed patient management. True and false positive blood cultures were based on Infectious Disease Society of America Guidelines, and change in management was defined as change in type or length of antibiotic therapy and was blindly adjudicated by a medical microbiologist. Results: 765 ED patients with sepsis met inclusion criteria. Mean age was 48.3 years and 57% were male. Blood cultures were positive in 99/765 (12.9%) subjects, of which 19 were false positive (19.2%). CRP was >20 mg/L in 595/765 (77.8%) of patients. Of 170 subjects with a CRP<20 mg/L, 3 had a positive blood culture (1.8%; 95% CI 0.1%- 5%). Management was not changed in any patient with a positive blood culture and CRP level<20 mg/L. Of 19 subjects with a false positive blood culture, CRP was <20 mg/L for 6 (31.6%). Conclusion: In this cohort of low-risk sepsis patients, based on a CRP of <20 mg/L, acquisition of blood cultures could be safely avoided in 22.2% of patients, at significant savings to the health care system.

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Evaluation of an intervention to decrease false positive blood culture contamination rates in Emergency Department

Journal of Emergency Medicine Trauma and Acute Care ◽

10.5339/jemtac.2016.icepq.89 ◽

2016 ◽

Vol 2016 (2) ◽

pp. 89

Author(s):

Parvathy Venugopal

Keyword(s):

Emergency Department ◽

Blood Culture ◽

Positive Blood Culture ◽

False Positive

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Passive Engineering Controls Result in Sustained 66% Reduction in Blood Culture Contamination

Infection Control and Hospital Epidemiology ◽

10.1017/ice.2020.955 ◽

2020 ◽

Vol 41 (S1) ◽

pp. s342-s343

Author(s):

Monica Baxter ◽

Carolyn Cook ◽

Angie James

Keyword(s):

Length Of Stay ◽

Blood Culture ◽

Positive Blood Culture ◽

False Positive ◽

Best Practice ◽

Medical Center ◽

Hospital Length Of Stay ◽

Trial Period ◽

True Negative ◽

Financial Benefits

Background: Blood culture testing is an important diagnostic tool in identifying the presence of microbes in the bloodstream. Tests are frequently contaminated, leading to false-positive results. Blood culture contamination can result in unnecessary antibiotic treatment, extended hospital length of stay, and patient exposure to hospital-acquired conditions. Methods: St. Mary’s Regional Medical Center (SMRMC) in Russellville, Arkansas, struggled with blood-culture contamination rates, with an average of 6.8% from 2014 to 2018. Ongoing staff education yielded a reduction to an average of 5%. In an effort to reduce the contamination rates, our facility elected to try a novel specimen diversion device. Laboratory and emergency department (ED) staff were educated on the diversion device prior to the initiation of the trial period. Compliance with the diversion device averaged 70%–75% during the trial period. Monitoring of contaminations was added to our daily safety huddle to provide a quick turnaround time for false-positive education to specific clinical staff. Results: The results were significant, with a decrease in contamination rates from 4.93% to 1.66%—a 66% reduction. Improved blood culture testing has several advantages: best practice for patient care is first and foremost, along with other financial benefits for the facility. Several articles have estimated the cost of a contaminated culture to be $3,000–$10,000 per event; SMRMC has adopting an estimated cost of $4,000. The number of cultures at our hospital averages ~4,400 per year, and these results suggest a savings of >$500,000 per year (as contaminations on an annual basis fell from 217 to 73). With this intervention, 144 patients were spared from receiving unnecessary antibiotics as a result of a false-positive blood culture testing. Conclusions: We conducted a brief analysis to determine whether there was any obvious change in length of stay for patients with a false-positive blood culture compared to those with true negative results. In analyzing data for 3 different months, patients with contaminated cultures spent an average of 3.97 additional days in the facility. In conclusion, the implementation of this specimen diversion device significantly lowered our contamination rates, was integrated into practice, and has provided clinical and financial benefits.Funding: NoneDisclosures: None

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