Predictive scoring models for persistent gram-negative bacteremia that reduce the need for follow-up blood cultures: a retrospective observational cohort study.

BACKGROUND: Although the risk factors for positive follow-up blood cultures (FUBCs) in gram-negative bacteremia (GNB) have not been investigated extensively, FUBC has been routinely carried out in many acute care hospitals. We attempted to identify the risk factors and develop a predictive scoring model for positive FUBC in GNB cases. METHODS: All adults with GNB in a tertiary care hospital were retrospectively identified during a 2-year period, and GNB cases were assigned to eradicable and non-eradicable groups based on whether removal of the source of infection was possible. We performed multivariate logistic analyses to identify risk factors for positive FUBC and built predictive scoring models accordingly. RESULTS: Out of 1473 GNB cases, FUBCs were carried out in 1268 cases, and the results were positive in 122 cases. In case of eradicable source of infection, we assigned points according to the coefficients from the multivariate logistic regression analysis: Extended spectrum beta-lactamase-producing microorganism (+ 1 point), catheter-related bloodstream infection (+ 1), unfavorable treatment response (+ 1), quick sequential organ failure assessment score of 2 points or more (+ 1), administration of effective antibiotics (- 1), and adequate source control (- 2). In case of non-eradicable source of infection, the assigned points were end-stage renal disease on hemodialysis (+ 1), unfavorable treatment response (+ 1), and the administration of effective antibiotics (- 2). The areas under the curves were 0.861 (95% confidence interval [95CI] 0.806-0.916) and 0.792 (95CI, 0.724-0.861), respectively. When we applied a cut-off of 0, the specificities and negative predictive values (NPVs) in the eradicable and non-eradicable sources of infection groups were 95.6/92.6% and 95.5/95.0%, respectively. CONCLUSIONS: FUBC is commonly carried out in GNB cases, but the rate of positive results is less than 10%. In our simple predictive scoring model, zero scores-which were easily achieved following the administration of effective antibiotics and/or adequate source control in both groups-had high NPVs. We expect that the model reported herein will reduce the necessity for FUBCs in GNB cases.

Impact of routine brain imaging on the prognosis of patients with left-sided valve infective endocarditis without neurological manifestations.

BACKGROUND: There are limited data on the impact of routine use of brain magnetic resonance imaging (MRI) on the prognosis of neurologically asymptomatic patients with left-sided infective endocarditis (IE). METHODS: Among patients diagnosed with possible or definite IE in two tertiary referral centers between January 2005 and March 2019, we identified 527 left-sided IE patients without neurological symptoms or signs at the time of diagnosis. Patients who underwent brain MRI within 1 week after the IE diagnosis were classified as the routine brain imaging group (n = 216), and the rest were categorized as the control group (n = 311). All-cause mortality at 3 months, attributable mortality (defined as death directly related to IE), and fatal neurological events compared after adjustment using inverse probability of treatment weighting (IPTW). RESULTS: During a median follow-up of 57 months, the routine brain imaging group had a similar risk of 3-month all-cause mortality to the control group in the multivariate analysis (hazard ratio [HR], 0.53; 95% confidence interval [CI], 0.24-1.14) and IPTW-adjusted cohort (HR, 0.59; 95% CI, 0.25-1.42). The risks of attributable mortality and fatal neurological events were also similar between the two groups in the multivariable analysis and IPTW-adjusted cohort. In the subgroup analysis, the routine brain imaging group showed more favorable outcomes in cases of large vegetation (> 10 mm) or acute-onset microorganisms. CONCLUSIONS: Routine use of brain MRI in left-sided IE patients without neurological manifestations is not associated with improved clinical outcomes. However, routine brain imaging in appropriate clinical settings could improve clinical outcomes.