Diagnosis of Coagulase-Negative Staphylococcus Bacteremia in Patients Receiving Extracorporeal Membrane Oxygenation.

Background: Coagulase-negative staphylococci (CoNS) are frequently cited as the most common cause of bacteremia in patients receiving extracorporeal membrane oxygenation (ECMO), yet there is significant variability in reporting rates between centers.

Methods: All patients who received ECMO with CoNS isolated from blood cultures between January 2022 and March 2024 were included in this retrospective cohort study. Previously reported bacteremia definitions were applied to determine the variability in rates by definition.

Results: In 68 patients who received ECMO during the study period, 424 blood culture sets were obtained, of which 20 (4%) yielded CoNS in 13 (19%) patients. Only 5 (38%) patients had repeat isolation. Clinical variables, such as fever and leukocytosis, did not predict repeat positivity. Rates of CoNS varied from 0-15 infections per 1000 ECMO days depending on the definition utilized.

Conclusion: CoNS were frequently isolated in blood cultures from patients receiving ECMO. Despite the concern for biofilm formation, most CoNS were only isolated in a single culture. With the limited utility of clinical markers and frequent false positives, clinicians should order repeat blood cultures on those with CoNS isolated from blood cultures. We propose a standardized definition for CoNS bacteremia which entails isolations of CoNS from two subsequent blood cultures.