Assessment of a rapid diagnostic test to exclude bacteraemia and effect on clinical decision-making for antimicrobial therapy

Abstract

Unnecessary antimicrobial treatment promotes the emergence of resistance. Early confirmation that a blood culture is negative could shorten antibiotic courses. the cognitor Minus test, performed on blood culture samples after 12 hours incubation has a negative predictive value (NPV) of 99.5%. The aim of this study was to determine if earlier confirmation of negative blood culture result would shorten antibiotic treatment. Paired blood cultures were taken in the Critical Care Unit at a teaching hospital. the cognitor Minus test was performed on one set >12 hours incubation but results kept blind. Clinicians were asked after 24 and 48 hours whether a result excluding bacteraemia or fungaemia would affect decisions to continue or stop antimicrobial treatment. Over 6 months, 125 patients were enrolled. The median time from start of incubation to Cognitor Minus test was 27.1 hours. When compared to 5 day blood culture results from both the control and test samples, Cognitor Minus gave NPVs of 99% and 100% respectively. Test results would have reduced antibiotic treatment in 14% (17/119) of patients at 24 and 48 hours (24% at either time) compared with routine blood culture. The availability of rapid tests to exclude bacteraemia may be of benefit in antimicrobial stewardship.

Rapid and precise identification of bloodstream infections using a pre-treatment protocol combined with high-throughput multiplex genetic detection system

“…In summary, the current study presents an integrated pre-treatment protocol that enables pathogen enrichment and inhibitor removal from whole blood samples, and establishes a rapid and robust multiplex pathogen identification system, BSI-HMGS, which allows the detection of 24 targets and covers the most common BSI pathogens. Given that in most laboratories, more than 80% of the blood cultures are negative[ 35 , 36 ], which may result in a lot of hands-on work for the few positive blood cultures, BSI-HMGS and pre-treatment protocol can be performed from positive or negative blood cultures and from whole blood only of critically ill patients according to particular request of the clinicians.…”

Blood Cultures and Molecular Diagnostics in Intensive Care Units to Diagnose Sepsis: A Bayesian Latent Class Model Analysis

“…In a recent ICU study using molecular diagnostics, it has been claimed that the negative predictive value of the test is 99.5%, and clinicians would be comfortable withholding antibiotics based on such a report. 26 These predictions may be optimistic as the specificity was calculated assuming STD methods as a gold standard, and the prevalence had not been taken into account. Additionally, in models A and B (conditional dependence assumption), the PPV when both tests are negative is in excess of 0.2 (0.2–0.75), suggesting that sepsis cannot be excluded even with both tests being negative.…”