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TOPLINE:

Time to positivity, defined as the interval between blood culture incubation and the detection of pathogen growth, demonstrated a non-linear relationship with disease severity in bloodstream infections. Shorter times to positivity were associated with higher rates of 30-day mortality.

METHODOLOGY:

• Researchers in Sweden conducted a population-based retrospective study to examine the association between the time to positivity and disease severity in bloodstream infections.
• They sourced data from regional healthcare databases and included 12,585 bloodstream infection episodes.
• Information on clinical characteristics, microbiological data, and prespecified disease severity markers (including laboratory values and vital signs) was also collected.
• The primary outcome was 30-day all-cause mortality.

TAKEAWAY:

• The rate of 30-day all-cause mortality was 14.4%, with an overall median time to positivity of 12.1 hours (95% CI, 9.7-17.7); a shorter time to positivity was non-linearly associated with mortality, with the risk increasing more steeply when the time to positivity was about 10 hours.
• A non-linear relationship was observed between shorter time to positivity and higher disease severity across all prespecified markers.
• Overall, 18.2% of patients were admitted to the intensive care unit or died within 30 days, and 47% of those events occurred within the first 3 days.
• The most prevalent pathogen categories in bloodstream infection episodes were Enterobacterales (38%), followed by Staphylococcus aureus (13%) and polymicrobial findings (12%).

IN PRACTICE:

"If TTP [time to positivity] is shown to have added value in predicting deterioration, real-time reporting of TTP could assist clinical decision-making. Our results could also motivate trials aiming to improve BSI [bloodstream infection] management, eg, by administering additional antimicrobial treatment, or by employing stricter monitoring protocols, in patients with shorter TTP," the authors wrote.

SOURCE:

This study was led by Oskar Ljungquist, MD, PhD, Division of Infection Medicine, Department of Clinical Sciences, Faculty of Medicine, Lund University, Lund, Sweden. It was published online on May 28, 2025, in Clinical Microbiology and Infection.

LIMITATIONS:

This study's retrospective design and incomplete data on disease severity markers may have introduced bias. Several severity indicators were collected primarily from patients with high disease severity, potentially leading to bias. As the investigation took place during the latter phase of the COVID-19 pandemic, the findings may not be fully representative of other periods.

DISCLOSURES:

This study was supported by the Governmental funding of research within clinical sciences and the Swedish Society for Medical Research. The authors declared having no competing interests.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.