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.

Mortality and risk factor analysis for Candida blood stream infection: A multicenter study

Candida blood stream infection (candidemia) is severe systemic infection mainly develops after intensive medical cares. The mortality of candidemia is affected by the underlying conditions, causative agents and the initial management. We retrospectively analyzed mortality-related risk factors in cases of candidemia between April 2011 and March 2016 in five regional hospitals in Japan. We conducted bivariate and multivariate analysis of factors including causative Candida species, patients' predisposing conditions, and treatment strategies, such as empirically selected antifungal drug and time to appropriate antifungal treatment, to elucidate their effects on 30-day mortality. The study enrolled 289 cases of candidemia in adults. Overall 30-day mortality was 27.7%. Forty-nine cases (17.0%) were community-acquired. Bivariate analysis found advanced age, high Sequential Organ Failure Assessment (SOFA) score, and prior antibiotics use as risk factors for high mortality; however community-acquired candidemia, C. parapsilosis candidemia, obtaining follow-up blood culture, and empiric treatment with fluconazole were associated with low mortality. Logistic regression revealed age ≥65 years (adjusted odds ratio, 2.13) and sequential organ failure assessment (SOFA) score ≥6 (6.30) as risk factors for 30-day mortality. In contrast, obtaining follow-up blood culture (0.38) and empiric treatment with fluconazole (0.32) were found to be protective factors. The cases with candidemia in associated with advanced age and poor general health conditions should be closely monitored. Obtaining follow-up blood culture contributed to an improved prognosis.

Follow-up blood cultures add little value in the management of bacteremic urinary tract infections

The need for mandatory confirmation of negative conversion in bacteremic urinary tract infection (UTI) has not been adequately addressed, even though follow-up blood cultures (FUBCs) are still prescribed liberally. The purpose of this study was to identify possible risk factors associated with positive FUBCs. We retrospectively collected data on adult cases of bacteremic UTI with at least one FUBC. Patients were divided into the negative FUBCs and the positive FUBC group, and data of both groups were compared. Of 306 cases of bacteremic UTI, 251 had a negative result from an FUBC and 55 had a positive result. Diabetes mellitus, malignancy, complicated UTI, and initial intensive care unit (ICU) admission were significantly more common in the positive FUBC group than in the negative group (all-P < 0.05). Time to defervescence was significantly longer in the positive FUBC group than in the negative group (52.2 h vs. 25.3 h, P < 0.05). A multivariate analysis showed that malignancy, initial ICU admission, CRP > 16 (mg/dL), and a time to defervescence of more than 48 h were significant factors associated with a positive FUBC. No subsequent cases of bacteremia developed in patients without risk factors associated with a positive FUBC. In bacteremic UTIs, patients with positive FUBCs usually present with higher initial inflammatory markers, longer time to defervescence, more frequent ICU admission rates, and an elevated chance of having cancer. More careful clinical assessment before drawing FUBCs would reduce costs and inconvenience to patients.