Image created by Dr. Michael J. Miller
More than half of patients with positive cultures for bloodstream infections achieved optimal therapy within 48 hours using the Biofire Blood Culture Identification 2 (BCID2; bioMérieux) panel, a rapid multiplex polymerase chain reaction–based diagnostic platform, in a single-center retrospective cohort study presented at MAD-ID 2025, in Orlando, Fla.
The study, conducted at Brigham and Women’s Hospital, in Boston, included hospitalized adult patients with at least one positive blood culture from March to June 2024 (abstract 5). The primary end point, median time to optimal antibiotic therapy, was 34.4 hours (IQR, 18.8-66.4), with 59.8% of patients achieving optimal therapy within 48 hours.
“Traditional antimicrobial [susceptibility] testing [AST] requires between 48 and 96 hours,” said presenting author Shahad Alghamdi, PharmD, a PGY-2 infectious diseases pharmacy resident. “Prior to adopting the BCID2 panel in January 2023, our time from collection to antimicrobial susceptibility testing results was 64 hours, right in the middle of that window. After adopting the BCID2, we found a mean of about 15 to 16 hours from time of blood collection to AST results. That mean time to optimal antibiotic therapy of 34.4 hours was even less than the lower end of the window just to get final susceptibility results prior to rapid diagnostic testing, which is impressive.”
The most frequently isolated bacteria were Escherichia coli (27%) and Staphylococcus aureus (23.8%), followed by Streptococcus pneumoniae and Streptococcus pyogenes (4.3% each). The study found no discrepancies between resistance gene detection by the BCID2 panel and standard finalized culture-based susceptibility results.
“Antibiotic utilization patterns changed significantly before and after optimization,” Dr. Alghamdi noted. “Prior to optimization, we relied heavily on the famous mix of cefepime and vancomycin, with about 65% of patients started empirically on an antipseudomonal and about 65% on an anti-MRSA [methicillin-resistant S. aureus], like vancomycin, linezolid or daptomycin. That was reduced significantly, after the results of Biofire and optimization, to 8.5% on antipseudomonals and 17% on anti-MRSA. That’s good for stewardship, good for cost and good for patient outcomes, because of course many of these antibiotics, especially vancomycin, are associated with toxicities like acute kidney injury.”
Among secondary outcomes, 30-day all-cause mortality was 9.2%. “Bloodstream infections do have a high risk of mortality, so that would be expected,” she said. The median hospital length of stay was nine days (IQR, 6-16), and Clostridioides difficile infection occurred within 90 days in 1.8% of patients.
“The absence of discrepancies between BCID2 and culture-based susceptibility results supports the reliability of rapid diagnostics in enhancing antimicrobial stewardship and optimizing treatment for patients with bloodstream infections,” Dr. Alghamdi concluded.