Association between follow-up blood cultures for gram-negative bacilli bacteremia and length of hospital stay and duration of antibiotic treatment: A propensity score-matched cohort study

It remains unclear whether a follow-up blood culture (FUBC) for gram-negative bacilli (GNB) bacteremia should be routinely or selectively performed. To evaluate the value of the practice, we analyzed the association between current FUBC practices and length of stay, antibiotic treatment duration, and in-hospital mortality. Retrospective cohort study. The study was conducted in 4 acute-care hospitals in New York City. The study included hospitalized adults with GNB bacteremia between 2017 and 2018. An FUBC was defined as a blood culture performed between 24 hours and 7 days after an initial blood culture positive for GNB. Using propensity scores for FUBCs performed, patients were matched 1:1 for outcome comparison. In total, 376 hospitalized adults with GNB bacteremia met eligibility criteria. Among them, FUBCs were performed in 271 patients (72%). After propensity score matching, we analyzed 87 pairs of patients with and without an FUBC to compare outcomes. The median length of stay was longer among patients with FUBCs than patients without FUBCs (9 days vs 7 days; P = .017). The median duration of antibiotic treatment was also longer among patients with FUBCs than patients without FUBCs (8 vs 6 days; P = .007). No statistically significant difference was observed in in-hospital mortality between patients with and without an FUBC (odds ratio, 0.37; 95% confidence interval, 0.08-1.36). Current FUBC practices for GNB bacteremia were associated with prolonged length of stay and duration of antibiotic treatment. Further data to better inform selectivity criteria for FUBCs in GNB bacteremia are needed.