The 24-h reporting of Gram stains from positive blood cultures contributes to physician's use of appropriate antimicrobials: Experience at a university hospital

Abstract

Although recent technological advances for the diagnosis of bloodstream infection (BSI) provide rapid and accurate results, blood culture maintains a key role in the diagnosis of BSI. The objective of this study was to determine whether 24-h reporting by telephone to disclose the suspected microorganism based on the Gram stain morphology from positive blood cultures (first laboratory report) affects a physician's use of appropriate antimicrobials. A total of 627 (14%) out of 4413 blood samples, excluding duplicate samples from the same patient on the same day, were positive for blood cultures between January and December 2016. The contamination rate of blood cultures during the study period was 2.3%. Among 627 patients with positive blood cultures, 538 (86%) were receiving antibiotics at the time of the first laboratory report, of which 502 (80%) thereafter continued the same antimicrobials, and the remaining 36 (6%) were changed to appropriate antimicrobials after the first laboratory report. An additional 25 (4%) were newly administered appropriate antimicrobials after the first laboratory report, whereas an additional 21 (3%) were newly administered appropriate antimicrobials after infection control team (ICT)-intervention. The median time lag (interquartile ranges) from flagging culture bottles as positive to a physician's use of appropriate antimicrobials after the first laboratory report (4 h, 2–7) was significantly (p < 0.001) shorter than that after ICT-intervention (12 h, 10–17). During the study period, no cases of discrepancy between the Gram stain morphology in the first laboratory report and definitive identification of microorganisms in the final laboratory report were observed. Because the timing of flagging culture bottles as positive tends to fall outside normal working hours, immediate 24-h reporting by telephone to disclose the suspected microorganism based on the Gram stain morphology from positive blood cultures may contribute to an early recognition of bacteremia and the physician's use of appropriate antimicrobials.