Positive Follow-up Blood Cultures Research Articles

Risk factors for positive follow-up blood cultures in Gram-negative bacteremia among immunocompromised patients with neutropenia.

Gram-negative bacillary bloodstream infection (GN-BSI) is a frequent clinical challenge among immunocompromised hosts and is associated with a high mortality. The utility of follow-up blood cultures (FUBCs) for GN-BSI in this population, particularly in the setting of neutropenia, is poorly defined. We conducted a single-center, retrospective cohort study between the period of July 2018 and April 2022 to investigate the utility of FUBCs and delineate risk factors for positive cultures among neutropenic patients with monomicrobial GN-BSI. Univariate logistic regression was performed to assess risk factors associated with positive FUBCs. Of 206 patients, 98% had FUBCs performed, and 9% were positive. Risk factors for positive FUBCs included multidrug-resistant GN infection (OR 3.26; 95% confidence interval [CI] 1.22-8.72) and vascular catheter source (OR 4.82; CI 1.76-13.17). Among patients lacking these risk factors, the prevalence of positive FUBCs was low (2.8%) and the negative predictive value was 92%. Those with positive and negative FUBCs had similar rates of all-cause mortality (16.7% vs. 16.6%; p=.942) and microbiologic relapse (11.1% vs. 6.0%; p=.401) within 90-days of treatment completion. However, positive FUBCs were associated with prolonged hospitalization and longer duration of antimicrobial therapy. Positive FUBCs were infrequent in neutropenic patients with GN-BSI, and their occurrence did not significantly impact mortality or microbiologic relapse. Risk factors for positive FUBCs included multidrug resistant Gram-negative infection and vascular catheter source. Prospective studies will be necessary to elucidate the benefits and risks of FUBCs when managing GN-BSI in patients with underlying immune compromise.

821. Positive Follow-Up Blood Culture in Candidemia and Ocular Involvement

Abstract Background Candidemia can lead to ocular complications, including endophthalmitis and chorioretinitis. Prompt management of such ocular diseases is paramount due to the risk of blindness. Management of candidemia usually includes a dilated ophthalmic exam; however, there are concerns regarding the utility of performing ophthalmic exams in all patients due to a low rate of ocular complications and lack of changes in medical management. Thus, there is a need for prognostic factors suggestive of ocular involvement that warrant a thorough ophthalmic examination. We sought to evaluate if positive repeat blood cultures are associated with ocular involvement in candidemia. Methods A single-center, retrospective chart review was conducted at an academic medical center. All candidemia cases from 2017 to 2022 were analyzed for demographics, culture results, treatment, inpatient ophthalmic exam findings, and mortality at discharge, at 30 days, and at 90 days. Descriptive statistics and Chi-Square tests were performed on the collected data. Results 104 episodes of candidemia among 84 patients were included: the mean age was 54 years, 55% were male, 74% were Black, and 13.1% were Latino. The most common Candida species isolated was C. albicans (37%) and most patients were treated with micafungin (51%). 12% had visual symptoms and 84% underwent ophthalmic exams. 15% of the exams were concerning for ocular involvement: 5% endophthalmitis, 5% chorioretinitis, and 5% other infectious findings (Roth spots and other retinal lesions). There was no significant association between repeat positive blood culture results and development of endophthalmitis (p = 1.00), chorioretinitis (p = 0.93), or any ocular involvement (p = 0.97). Furthermore, no significant associations were found between repeat blood culture and death at discharge, 30 days, or 90 days. Conclusion No significant associations were found between repeat positive blood culture and ocular involvement in the setting of candidemia. Other indicators of ocular involvement in candidemia are needed to assess patients who would benefit from ophthalmic exam. Disclosures All Authors: No reported disclosures

The effect of follow-up blood cultures on mortality and antibiotic use in gram-negative bloodstream infections

BackgroundGram-negative bloodstream infections (GN-BSIs) are a significant clinical challenge. The utility of follow-up blood cultures (FUBCs) in GN-BSIs and their impact on mortality and antibiotic consumption are areas of debate. This study aimed to evaluate the effect of FUBCs on mortality and antibiotic consumption in patients with GN-BSIs.MethodsThis single-center, retrospective study was conducted in aged > 18 years of patients with GN-BSIs. FUBC was defined as a blood culture performed 2–7 days after the first blood culture. Patients were grouped as FUBC and no FUBC and compared. A 1:1 match analysis was performed between the groups according to the SOFA score. The matched subgroup was compared for mortality risk factors with logistic regression models. The two groups were compared for the duration of effective antibiotic therapy and total antibiotic consumption (days of therapy per 1000 patient days (DOT/1000 PD)).ResultsFUBC was performed in 564 (69.4%) of 812 patients. Persistent, positive and negative FUBC rates were 7.9%, 14%, and 78%, respectively. The frequency of persistent GN-BSI in patients with appropriate antibiotic therapy was 3.9%. SOFA score (OR:1.33; 95% CI, 1.23–1.44), Charlson comorbidity index score (OR:1.18; 95% CI, 1.08–1.28), hospital-acquired infections (OR:1.93; 95% CI, 1.08–3.46) and carbapenem-resistant GN-BSI (OR: 2.92; 95% CI, 1.72–4.96) were independent risk factors for mortality. No relationship was found between FUBC and mortality (p > 0.05). Duration of effective antibiotic therapy (10(4–16) vs. 15(9–20), p < 0.001) and DOT/1000 PD (1609 (1000–2178) vs. 2000 (1294–2769), p < 0.001) were longer in the FUBC group.ConclusionRoutine FUBC should not be recommended because of the low prevalence of persistent infections in patients under appropriate antibiotic therapy and FUBC increases antibiotic consumption.

Predictors of Positive Repeat Blood Cultures in Patients With Gram-Negative Bacilli Bacteremia

Introduction Bloodstream infections occur commonly in the United States and are associated with significant morbidity and mortality. Bacteremia caused by gram-positive organisms has established guidelines for the use of follow-up blood cultures (FUBCs), whereas the use of FUBCs in bacteremia due to gram-negative bacilli (GNBs) does not. One study showed that positive FUBCs were more common in gram-positive coccus bacteremia (21%) than in GNB bacteremia (6%), calling into question the overall clinical utility of using FUBCs in GNB bacteremia. We investigated the factors associated with positive FUBCs in patients with GNB bacteremia in our institution to better guide clinical practice. Methods We used a case-control design for this study. We included patients 18 years or older admitted to our hospitals between January 1, 2014, and December 31, 2018, for a duration of ≥24 hours and who had a positive blood culture (BC) for GNB. Cases were defined as any patient with a positive FUBC drawn ≥24 hours after the initial positive BC. Control subjects were defined as patients with a negative FUBC after an initial positive BC. Characteristics of cases and control subjects were compared using descriptive statistics. A multivariable regression model using stepwise variable selection was used to identify factors significantly associated with having a positive FUBC. Results We identified 70 cases meeting the inclusion criteria. We compared these 70 cases with 528 control subjects. The cases and control subjects did not differ significantly in age, sex, race, or other predefined comorbid conditions. Significant predictors for having a positive FUBC included (1) organism resistance to initial antibiotic therapy (odds ratio [OR], 3.26; P = 0.035), (2) glomerular filtration rate less than 30 mL/min (OR, 2.35; P = 0.010), (3) initial admission to critical care unit (OR, 1.72; P = 0.049), (4) central line–associated infection (OR, 3.99; P = 0.004), (5) Klebsiella group infection (OR, 2.18; P = 0.015), and (6) Serratia marcescens infection (OR, 3.53; P = 0.037). Initial discordant BC was a negative predictive factor (OR, 0.44; P = 0.018). Follow-up blood culture drawn more than 48 hours after the initial positive BC had a lower likelihood of being positive than those drawn 24 to 48 hours after the initial BC (OR, 0.59; P = 0.037). Discussion We identified 6 independent risk factors for positive FUBCs as delineated previously. These factors provide guidance for further research and for future guideline development. The timing of the FUBCs had a significant impact on positivity. Follow-up blood cultures in GNB bacteremia should be obtained more than 48 hours after the initial positive BC.

Association of Follow-up Blood Cultures With Mortality in Patients With Gram-Negative Bloodstream Infections

Obtaining follow-up blood cultures (FUBCs) in patients with Staphylococcus aureus bloodstream infection (BSI) is standard practice, although its utility in patients with gram-negative bacterial BSI (GN-BSI) is unclear. To examine whether obtaining FUBCs is associated with decreased mortality (key question [KQ] 1) and whether positive vs negative FUBCs are associated with increased mortality (KQ2). MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Web of Science, and gray literature were searched from inception to March 11, 2022. Two investigators used predefined eligibility criteria to independently screen titles, abstracts, and relevant full texts. Randomized clinical trials or observational studies that matched or statistically adjusted for differences in, at minimum, level of acute illness between patients in the intervention (eg, FUBCs obtained) and control (eg, FUBCs not obtained) groups were included in primary analyses. Articles published in languages other than English were excluded. Data abstraction and quality assessments were performed by one investigator and verified by a second investigator. Risk of bias was assessed with the Newcastle-Ottawa Scale. Effect sizes were pooled using random-effects models. The study followed the Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guideline. Mortality before hospital discharge or up to 30 days from the index blood culture. From 3495 studies, 15 were included (all nonrandomized). In the 5 studies (n = 4378 patients) that met criteria for the KQ1 primary analysis, obtaining FUBCs was associated with decreased mortality (hazard ratio, 0.56; 95% CI, 0.45-0.71). For KQ2, 2 studies met criteria for the primary analysis (ie, matched or statistically adjusted for differences in patients with positive vs negative FUBCs), so an exploratory meta-analysis of all 9 studies that investigated KQ2 (n = 3243 patients) was performed. Positive FUBCs were associated with increased mortality relative to negative blood cultures (odds ratio, 2.27; 95% CI, 1.54-3.34). Limitations of the literature included a lack of randomized studies and few patient subgroup analyses. In this systematic review and meta-analysis, obtaining FUBCs in patients with GN-BSI was associated with decreased mortality. The benefit of FUBCs may stem from identification of patients with positive FUBCs, which was a poor prognostic marker.

Persistent Methicilin-Resistant Staphylococcus aureus Bacteremia: Resetting the Clock for Optimal Management.

A positive follow-up blood culture for methicillin-resistant Staphylococcus aureus (MRSA) while on seemingly appropriate therapy is a common and ominous development. However, the definition and management of persistent MRSA bacteremia is unstandardized. In this Opinion Paper, we identify the presence of bacteremia for > 1 calendar day as a "worry point" that should trigger an intensive diagnostic evaluation to identify metastatic infection sites. Next, we define the duration of MRSA bacteremia that likely constitutes antibiotic failure and outline a potential management algorithm for such patients. Finally, we propose pragmatic clinical trial designs to test treatment strategies for persistent MRSA bacteremia.

Follow-up Blood Culture Practices for Gram-Negative Bloodstream Infections in Immunocompromised Hosts at a Large Academic Medical Center

The role of follow-up blood cultures (FUBCs) in gram-negative bloodstream infections to improve clinical outcomes remains controversial, especially among immunocompromised patients. Among 139 patients, FUBCs were common (117, 84.2%); however, positive FUBCs were rare (3, 2.6%). Only presence of fever was associated with a positive FUBC.

Bedside risk prediction for positive follow-up blood culture in Gram-negative bacilli bacteremia: for whom is follow-up blood culture useful?

The value of follow-up blood culture (FUBC) in Gram-negative bacteremia (GNB) management is controversial. We evaluated bedside risk predictors and their probabilities of yielding positive FUBCs in GNB. All adult patients with GNB in a 2700-bed tertiary center were retrospectively enrolled between January 2019 and December 2019. Only one initial GNB episode was included per patient. Positive FUBC was defined as isolation of the same organism in blood culture 48-72h after the initial blood culture. A total of 2216 patients with GNB were identified, of whom 34.4% underwent FUBC. Of the 645 patients with FUBCs analyzed in the study, 89 (13.8%) had positive FUBCs. In multivariate analysis, hemodialysis [adjusted odds ratio (aOR), 2.6], fever on the day of FUBCs (aOR 3.6), intravascular device (aOR 2.4), no use of in vitro active antibiotic within 24h (aOR 2.5), non-fermenting bacteria (aOR 4.7), and multidrug resistance (aOR 5.4) were independent risk factors for positive FUBCs. If microbiological results were excluded in multivariate analysis, hemodialysis, immunosuppressive treatment, fever on the day of FUBCs, and intravascular device were independent bedside risk predictors for positive FUBCs. The yield of FUBCs increased from 3.0% (95% CI 1.0-7.0) to 63.6% (95% CI 25.6-100) as the number of bedside risk predictors increased from 0 to 4. In addition, positive FUBCs were significantly associated with 30day mortality. FUBCs may not need to be routinely used for patients with GNB bacteremia, and bedside risk predictors could be helpful in identifying patients for whom FUBC is likely to be useful.

62. Follow-Up Blood Culture Practices for Gram-Negative Bloodstream Infections in Immunocompromised Hosts at a Large Academic Medical Center

BackgroundRoutine follow-up blood cultures (FUBC) are strongly recommended for Staphylococcus aureus and Candida spp. bloodstream infections (BSI), but the role of FUBC in Gram-negative (GN) BSI remains controversial. Factors that may result in persistent GN BSI include critical illness, endovascular infection, lack of source control, multidrug resistant organisms (MDRO), end-stage renal disease, or immunocompromised status. As such, FUBC in patients with any of these factors may be warranted to improve clinical outcomes, but the true balance of benefit versus harm remains unknown. Our objective was to evaluate the role of FUBC in immunocompromised patients with GN BSI.MethodsThis was a retrospective observational cohort of adult, immunocompromised patients treated for confirmed GN BSI between January 2019 and December 2020 at University of Maryland Medical Center. Immunocompromise was defined as active hematologic or solid tumor malignancy at time of BSI diagnosis, history of hematopoietic stem cell transplantation (HSCT) or solid organ transplantation (SOT), or absolute neutrophil count (ANC) < 1000 cells/mm3 at any time 30 days prior to BSI diagnosis. FUBC were defined as blood cultures drawn between 24 hours and 7 days from index blood culture, within the same hospital encounter. Positive FUBC was defined as a FUBC with same pathogenic GN organism identified. Comparison of patient and microbiologic characteristics was made between patients with and without FUBC.ResultsA total of 146 patients with GN BSI were included. Baseline characteristics are reported in Table 1. FUBC were collected in 129 (88.4%) patients. Neutropenia (49.6% vs. 19.4%, P=0.122), presence of central line (69.8% vs. 30.2%, P=0.061), and hospital-acquired origin of BSI (63.6% vs. 36.4%, P=0.395) resulted in increased frequency of FUBC. Patients with FUBC had a significantly longer post-BSI mean (SD) length of stay (17.3 [35.4] vs. 6.5 [6.0] days; P=0.005). Positive FUBC occurred in only 2 cases (1.4%) and both patients had persistent fevers at time of FUBC. Table 1. Baseline Characteristics ConclusionPositive FUBC were uncommon in this immunocompromised cohort with GN BSI, which challenges the need for routine collection of FUBC in this patient population.Disclosures Ciera L. Bernhardi, PharmD, Servier Pharmaceuticals (Advisor or Review Panel member) J. Kristie Johnson, PhD, D(ABMM), GenMark (Speaker’s Bureau) Kimberly C. Claeys, PharmD, GenMark (Speaker’s Bureau)

Follow-Up Blood Cultures in Young Infants With Bacteremic Urinary Tract Infections.

Researchers in previous studies suggest that the clinical yield of follow-up blood cultures (FUBCs) is low in infants with bacteremic urinary tract infection (UTI) because persistent bacteremia is rare; however, no researchers have analyzed the practice of routinely obtaining FUBCs. In our study, we evaluate outcomes in infants with FUBCs, examine opportunities for improvement of blood culture practices, and add important information to inform both clinical practice as well as further study. This retrospective cohort study included infants <90 days of age with bacteremia and UTI with the same pathogen at 22 hospitals that make up Intermountain Healthcare between 2002 to 2020. Infants with culture proven meningitis, osteomyelitis, central line infection, and infections occurring during NICU hospitalization were excluded. Total number of patients with bacteremic UTI was 174, 153 (88%) patients had at least 1 FUBC, 14 of 153 (9%) had a positive FUBC with same organism, and 4 of 153 (3%) were contaminants. The length of stay was longer for patients with positive FUBCs. Patients with Escherichia coli are more likely to have a negative FUBC. Readmissions within 30 days were similar among infants with positive FUBCs, negative FUBCs, and no FUBCs. FUBCs in infants with bacteremic UTI should not be routinely performed, especially for E coli, and it is unclear whether FUBCs improve outcomes.

Follow-up blood cultures in E. coli and Klebsiella spp. bacteremia-opportunities for diagnostic and antimicrobial stewardship.

Uncomplicated Enterobacteriaceae bacteremia is usually transient and may not require follow-up blood cultures (FUBC). This is a retrospective observational study conducted at a university-affiliated urban teaching hospital in Seattle, WA. All patients ≥ 18years hospitalized between July 2014 and August 2019 with ≥ 1 positive blood culture for either Escherichia coli or Klebsiella species were included. The primary outcome was to determine the number and frequency of FUBC obtained, and the detection rate for positive FUBC. There were 335 episodes of E. coli and Klebsiella spp. bacteremia with genitourinary (54%) being the most common source. FUBC were sent in 299 (89.3%) patients, with a median of 3 (interquartile range (IQR): 2, 4) sets of FUBC drawn per patient. Persistent bacteremia occurred in 37 (12.4%) patients. In uncomplicated E. coli and Klebsiella spp. bacteremia, when the pre-test probability of persistent bacteremia is relatively low, FUBC may not be necessary in the absence of predisposing factors.

Limited Clinical Utility of Follow-up Blood Cultures in Patients With Streptococcal Bacteremia: An Opportunity for Blood Culture Stewardship.

BackgroundThe value of positive follow-up blood cultures (FUBCs) in streptococcal bacteremia has not been well defined. Therefore, we explored the frequency of and risk factors for positive FUBC in a retrospective cohort of patients with streptococcal bacteremia.MethodsAdults ≥18 years of age, admitted with at least 1 positive blood culture for Streptococcus spp between 2013 and 2018 followed by at least 1 FUBC, were potentially eligible. Positive FUBCs were defined as cultures positive for the same streptococcal species drawn >24 hours after the index culture. We excluded patients with polymicrobial bacteremia. We compared the characteristics of patients with and without a positive FUBC.ResultsIn our single-center cohort, we identified 590 patients with streptococcal bacteremia, and 314 patients met inclusion criteria. Ten patients had FUBC with Streptococcus spp (3.2%), 4 (1.3%) had a contaminant identified, and 3 (1.0%) had a new pathogen isolated. Endocarditis (5 of 10 [50.0%] vs 35 of 304 [11.5%]), epidural abscess (2 of 10 [20%] vs 4 of 304 [1.3%]), and discitis or vertebral osteomyelitis (3 of 10 [30.0%] vs 14 of 304 [4.6%]) were associated with positive FUBC. Patients with positive FUBC had a longer median length of stay (12.9 vs 7.1 days, P = .004) and longer duration of antibiotic treatment (14.9 vs 43.2 days, P = .03).ConclusionsFollow-up blood cultures among patients with streptococcal BSI are rarely positive. Clinicians could consider limiting follow-up blood cultures in patients at low risk for deep-seated streptococcal infections, persistent bacteremia, or endovascular infection.

Clinical Characteristics and Outcomes of S. Aureus Bacteremia in Patients Receiving Total Parenteral Nutrition.

Background: Patients on total parenteral nutrition (TPN) are at risk of developing central line-associated infections. Specifically, Staphylococcus aureus bacteremia (SAB) is feared for its high complication rates. This prospective cohort study compares characteristics, clinical course and outcome of SAB in patients with and without TPN support. Methods: Clinical and microbiological data from all patients with positive blood cultures for S. aureus from two facilities, including our referral center for TPN support, were retrieved (period 2013–2020). Primary outcome was overall mortality, and included survival analysis using a multivariate Cox regression model. Secondary outcomes comprised a comparison of clinical characteristics and outcomes between both patient groups and analysis of factors associated with complicated outcome (e.g., endocarditis, deep-seated foci, relapse and death) in patients on TPN specifically. Results: A total of 620 SAB cases were analyzed, of which 53 cases received TPN at the moment the blood culture was taken. Patients in the TPN group were more frequently female, younger and had less comorbidity (p < 0.001). In-hospital death and overall mortality were significantly lower in TPN patients (4% vs. 18%, p = 0.004 and 10% vs. 34%, p < 0.001, respectively). Positive follow-up blood cultures, delayed onset of therapy and previous catheter problems were associated with a higher incidence of complicated SAB outcome in patients on TPN. Conclusion: Our data show that patients on TPN have a milder course of SAB with lower mortality rates compared to non-TPN SAB patients.

&lt;p&gt;Predictors of Mortality in Patients with Carbapenem-Resistant Gram-Negative Bacilli or Vancomycin-Resistant Enterococci Bacteremia&lt;/p&gt;

PurposeThe incidences of carbapenem-resistant gram-negative bacilli (CRGNB) and vancomycin-resistant Enterococci (VRE) have increased rapidly in South Korea since 2000. The mortality rate for CRGNB or VRE bacteremia cases is higher than that for non-resistant bacteremia cases. The factors associated with higher mortality are unclear. We investigated the factors associated with mortality from CRGNB or VRE bacteremia and compared the relative risk of these factors.Patients and MethodsWe retrospectively collected data from adult patients with CRGNB or VRE bacteremia. Patients were grouped according to whether they survived or died. The data from both groups were compared.ResultsDuring the study period, 171 cases of CRGNB or VRE bacteremia were identified, of which 100 were CRGNB bacteremia cases and 71 were VRE bacteremia cases. Multivariate analysis revealed significant associations with Pitt bacteremia score (PBS) (odds ratio [OR] 1.329, 95% confidence interval [CI] 1.049–1.684). In the multivariate analysis, negative conversion of follow-up blood culture (FUBC) was related with one-week mortality from CRGNB or VRE bacteremia (OR 17.623, 95% CI 5.726–54.244). In the multivariate analysis of risk factors for 28-day mortality for CRGNB or VRE bacteremia, the significant risk factors were bacteremia of respiratory origin (OR 4.491, 95% CI 1.622–12.435) and positive FUBC (OR 4.082, 95% CI 1.626–10.204).ConclusionDespite the high mortality rate in patients with CRGNB or VRE bacteremia, the related mortality could be predicted by independent risk factors of PBS, positive FUBC, and bacteremia of respiratory origin.

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

BackgroundAlthough 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.MethodsAll 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.ResultsOut 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.ConclusionsFUBC 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.

Risk Factors for Positive Follow-Up Blood Cultures in Gram-Negative Bacilli Bacteremia: Implications for Selecting Who Needs Follow-Up Blood Cultures.

BackgroundThe value of follow-up blood cultures (FUBCs) to document clearance of bacteremia due to Gram-negative bacilli (GNB) has not been well established. Although previous studies suggested that the yield of FUBCs for GNB bacteremia is low, it remains to be elucidated for whom FUBC may be beneficial and for whom it is unnecessary.MethodsA retrospective cohort study was performed at 4 acute care hospitals to identify risk factors for positive FUBCs with GNB bacteremia and to better guide clinicians’ decisions as to which patients may or may not benefit from FUBCs. Participants included adult patients with GNB bacteremia who had FUBCs and were admitted between January 2017 and December 2018. The primary outcomes were the factors associated with positive FUBCs and the yield of FUBCs with and without the factors.ResultsOf 306 patients with GNB bacteremia who had FUBCs, 9.2% (95% confidence interval, 6.2%–13.0%) had the same GNB in FUBCs. In the multivariate logistic regression analysis, end-stage renal disease on hemodialysis, intravascular device, and bacteremia due to extended-spectrum β-lactamase or carbapenemase-producing organism were identified as independent predictors of positive FUBCs with GNB bacteremia. Approximately 7 FUBCs and 30 FUBCs were needed for patients with ≥1 or no risk factors, respectively, to yield 1 positive result.SummaryThis multi-site retrospective cohort study found that among patients with gram-negative bacilli (GNB) bacteremia, having ESRD on hemodialysis, intravascular devices, or bacteremia due to multi-drug resistant GNB were each independently associated with having a positive follow-up blood culture.ConclusionsFollow-up blood culture may not be necessary for all patients with GNB bacteremia and has the highest yield in patients with 1 or more risk factors.

Positive follow-up blood cultures identify high mortality risk among patients with Gram-negative bacteraemia

ObjectivesThe role of follow-up blood cultures (FUBCs) in the management of Gram-negative bacteraemia (GNB) is poorly understood. We aimed to determine the utility of FUBCs in identifying patients with increased mortality risk. MethodsAn observational study with a prospectively enrolled cohort of adult inpatients with GNB was conducted at Duke University Health System from 2002 to 2015. FUBCs were defined as blood cultures performed from 24 hours to 7 days from initial positive blood culture. ResultsAmong 1702 patients with GNB, 1164 (68%) had FUBCs performed. When performed, FUBCs were positive in 20% (228/1113) of cases. FUBC acquisition was associated with lower all-cause in-hospital mortality (108/538, 20%, vs. 176/1164, 15%; p 0.01) and attributable in-hospital mortality (78/538, 15%, vs. 98/1164, 8%; p < 0.0001). Propensity score–weighted Cox proportional hazards models revealed that obtaining FUBCs was associated with reductions in all-cause (hazard ratio (HR) 0.629; 95% confidence interval (CI), 0.511–0.772; p < 0.0001) and attributable mortality (HR 0.628; 95% CI, 0.480–0.820; p 0.0007). Positive FUBCs were associated with increased all-cause mortality (49/228, 21%, vs. 110/885, 11%; p 0.0005) and attributable mortality (27/228, 12%, vs. 61/885, 7%; p 0.01) relative to negative FUBCs. Propensity score–weighted Cox proportional hazards models revealed that positive FUBCs were associated with increased all-cause (HR 2.099; 95% CI, 1.567–2.811; p < 0.0001) and attributable mortality (HR 1.800; 95% CI, 1.245–2.603; p 0.002). In a calibration analysis, a scoring system accurately identified patients at high risk of positive FUBCs. ConclusionsRates of positive FUBCs were high and identified patients at increased risk for mortality. Clinical variables can identify patients at high risk for positive FUBCs. FUBCs should be considered in the management of GNB.

Follow-up blood cultures in Gram-negative bacilli bacteremia: are they needed for critically ill patients?

Gram-negative bacilli bacteremias (GNB-Bs) represent a major cause of morbidity and mortality in Intensive Care Unit (ICU) patients. Aim of this study was to investigate the role of follow-up blood cultures (FUBCs) and the clinical significance of persistent bacteremia (PB) in these settings. We retrospectively analyzed clinical data and outcome of GNB-Bs that occurred in ICU patients over a span of 1 year. In particular we sought information on development and clinical details of PB, defined as repeatedly positive FUBCs after ≥96 hours of appropriate antibiotic treatment and ≥48 hours after removal of endovascular devices. Among 307 ICU patients, 69 (22.4%) developed 107 GNB-Bs. Of these, 78 (73%) could be eventually analyzed: 50 of 78 (64.1%) were non-PBs from 26 patients and 28 of 78 (35.9%) were PBs from 23 patients. Duration of fever and bacteremia, time to procalcitonin normalization and weaning from vasopressors were longer in episodes of PBs than non-PBs (P=0.04, P<0.001, P=0.02 and P=0.004, respectively). Primary bacteremia was more frequent in non-PBs than in PBs (29 of 50, 58% vs. 3/28, 10.7%, P=0.0001), whereas septic thrombus infection (STI) was the source of infection in 14 of 28 (50%). Finally, clinical features and 30-day mortality did not differ between patients with PB and those who developed only non-PB episodes. Among our ICU patients, more than one third of GNB-Bs for which FUBCs were performed resulted PB. This condition is often associated with the presence of STI; therefore, FUBCs seem useful for the optimal management of GNB in this clinical setting.

118. Factors Associated with Positive Follow-up Blood Cultures in Gram-Negative Septicemia

BackgroundBloodstream infections remain a significant cause of morbidity and mortality. No guidelines for the management of noncatheter-associated Gram-negative septicemia exist. There is considerable debate regarding the role of follow-up blood cultures. Studies have shown inadequate antibiotic therapy increases mortality in Gram-negative sepsis. We evaluated factors associated with a higher likelihood of positive follow-up blood cultures (FUBC).MethodsA retrospective cohort study was conducted to look at factors associated with an increased likelihood of positive FUBC. Data were obtained via Epic chart review. Empiric antimicrobial regimens were reviewed in all patients with MDRO infections.ResultsWe identified 1,527 patients ≥18 years admitted with gram-negative septicemia from January 1, 2013 through January 1, 2018. A total of 8.4% had positive FUBC. Patients with positive FUBC had a younger median age than the no-growth group (64.7 vs. 69.4, P <0.001). Admission systolic blood pressure was lower in the group with positive FUBC than the no-growth group (107 vs. 116, P = 0.008). The odds ratio for positive FUBC for cardiac device was 2.08 (95% CI = [0.97, 4.35], P = 0.061); central line infection (vs. urinary tract infection) adjusted odds ratio was 2.08 (95% CI = [1.10, 3.95], P = 0.025). The positive FUBC group had a larger proportion of multidrug-resistant organisms (MDRO) (21.9% vs. 10.4%, P < 0.001) with an odds ratio of 2.40 (95% CI = [1.53, 3.78]). In this group, those who received inadequate empiric antibiotics had a significantly higher percentage of repeat positive results (78.6% vs. 57.1%, P = 0.033). In summary, patients with either an MDRO, a central line infection (vs. urinary tract infection), or the presence of a cardiac device (vs. no cardiac device present) had over twice the odds of positive FUBC than those without.ConclusionThough the role of FUBC for Gram-negative septicemia has been brought into question, our results show that the presence of central lines, cardiac devices, infections with MDRO organisms, or inadequate empiric antibiotics on admission were factors strongly correlated with subsequent positive FUBC. Therefore, we believe that repeating blood cultures in this subset of patients require further study and consideration.Disclosures All authors: No reported disclosures.

188. Which patients with gram-negative bacteremia need follow-up blood cultures?

BackgroundUniversal follow-up blood culture (FUBC) in gram-negative bacteremia (GNB) is not recommended, but it has been routinely conducted in many acute-care hospitals. In contrast with Staphylococcus aureus bacteremia, risk factors for positive FUBC in GNB have not been well investigated. Therefore, we tried to identify the risk factors for and develop predictive scores of positive FUBC.MethodsAll adults (≥18 years-old) with GNB were identified in a tertiary-care hospital during the 2-year period, retrospectively. Death within 2 days of GNB and polymicrobial infection with gram-positive bacteria or fungus were excluded. GNB were classified into eradicable and non-eradicable source of infection groups, according to the possibility of source removal. We performed multivariate analyses for identifying risk factors for positive FUBC and built prediction scores using the coefficients of the multivariate logistic regression models.ResultsOf total 1,473 GNB, FUBC was drawn in 1,268 (86%) patients and 122 (9.6%) had positive results. In patients with eradicable source of infection, ESBL-producing microorganism, catheter-related bloodstream infection, unfavorable treatment response, and quick sequential organ failure assessment (qSOFA) score (≥2) were associated. On the other hand, administration of effective antibiotics and adequate source control were negatively associated with positive FUBC. In non-eradicable source of infection, end-stage renal disease on hemodialysis, and unfavorable treatment response were related to positive FUBC and administration of effective antibiotics was negatively associated (Table 1). When we built prediction scores according to the coefficients, the areas under the curves were 0.864 (95% confidence interval [CI95] 0.816–0.912) and 0.792 (CI95, 0.721–0.861), respectively. When we applied a cutoff of 0, specificities/negative predictive values in eradicable and non-eradicable source of infection groups were 84.7%/95.6% and 95.5%/95.0%, respectively (Table 2).ConclusionOur prediction scores based on adequate source control and use of effective antibiotics showed high specificities and negative predictive values. Therefore, we could expect these score systems to contribute to reducing unnecessary FUBC in GNB. Disclosures All authors: No reported disclosures.