Bottom Line: In adults presenting to the ED with bacteremia, bandemia may be associated with increased short-term mortality, with higher band percentages correlating with greater risk. Although bacteremia is rarely diagnosed during the ED visit because blood cultures require time to result, the presence of bandemia should raise concern for possible occult critical illness.

Additional Information

Bandemia refers to an elevated number of banded (immature) neutrophils in the peripheral blood, reflecting bone marrow stimulation in response to infection. In this study, the authors evaluated the association between bandemia and short-term mortality.

This single-center retrospective cohort study was conducted in Taiwan from 2018 to 2023. The authors screened all ED encounters in which blood cultures were obtained. Eligible participants were treatment-naive adults with confirmed bacterial growth in blood cultures collected during the ED stay. Patients were excluded if blood cultures were deemed contaminants or if they had received antibiotics prior to ED presentation.

A total of 5,558 patients were included, with an overall 30-day mortality rate of 16.1%. Patients were stratified by band percentage: <10%, 10–19%, 20–29%, 30–39%, and ?40%. Each 10% increase in initial band percentage was independently associated with a 12% increase in 30-day mortality.

Bottom Line: In adults presenting to the ED with bacteremia, bandemia may be associated with increased short-term mortality, with higher band percentages correlating with greater risk. Although bacteremia is rarely diagnosed during the ED visit because blood cultures require time to result, the presence of bandemia should raise concern for possible occult critical illness.

References

Cheng H, et al. Association between initial bandemia degree and short-term mortality among adults with bacteremia in the emergency department. Am J Emerg Med. 2026;103. doi:10.1016/j.ajem.2026.05.008