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

Follow-up blood cultures do not reduce mortality in hospitalized patients with Gram-negative bloodstream infection: a retrospective population-wide cohort study

OBJECTIVES

The utility of follow-up blood cultures (FUBCs) in patients with Gram-negative bloodstream infection (GN-BSI) is controversial. Observational studies have suggested significant mortality benefit but may be limited by single-centre designs, immortal time bias, and residual confounding. We examined the impact of FUBCs on mortality in patients with GN-BSI in a retrospective population-wide cohort study in Ontario, Canada.

METHODS

Adult patients with GN-BSI hospitalized between April 2017 and December 2021 were included. Primary outcome was all-cause mortality within 30 days. FUBC was treated as a time-varying exposure. Secondary outcomes were 90-day mortality, length of stay, and number of days alive and out of hospital at 30 and 90 days.

RESULTS

Thirty-four thousand one hundred patients were included; 8807 (25.8%) patients received FUBC, of which 966 (11.0%) were positive. Median proportion of patients receiving FUBC was 18.8% (interquartile range, 10.0-29.7%; range, 0-66.1%) across 101 hospitals; this correlated with positivity and contamination rate. Eight hundred ninety (10.1%) patients in the FUBC group and 2263 (8.9%) patients in the no FUBC group died within 30 days. In the fully adjusted model, there was no association between FUBC and mortality (hazard ratio, 0.97; 95% CI, 0.90-1.04). Patients with FUBC had significantly longer length of stay (median, 11 vs. 7 days; adjusted risk ratio, 1.18; 95% CI, 1.16-1.21) and fewer number of days alive and out of hospital at 30 and 90 days.

DISCUSSION

FUBC collection in patients with GN-BSI varies widely across hospitals and may be associated with prolonged hospitalization without clear survival benefit. Residual confounding may be present given the observational design. Clear benefit should be demonstrated in a randomized trial before widespread adoption of routine FUBC.

Predictors of antibiogram performance and antibiotic resistance patterns in the northern Syrian region: A cross-sectional investigation

Introduction

Antibiogram use is crucial in the fight against antibiotic resistance in Syria, helping to guide treatment decisions, monitor resistance trends, and implement measures to mitigate this global health threat. This study explores the predictors of antibiogram performance and antibiotic resistance patterns in hospital settings in the Northern Syrian region.

Methods

An observational cross-sectional study was performed over six months, from the beginning of September 2022 to February 2023, targeting patients admitted to two hospitals in Syria with susceptibility to infection. The study excluded patients who did not consent or were unwilling to participate, while all individuals admitted due to infectious diseases, regardless of age, sex, or race, were included in the research. Data were collected prospectively, and antimicrobial susceptibility evaluations were performed using the disc diffusion method (the Kirby-Bauer test). Statistical analyses, including the analysis of the results, were conducted utilizing the Statistical Package for Social Sciences (SPSS Inc., Chicago, Illinois) Version 29.

Results

Of 300 hospitalized patients taking antibiotics, an antibiogram was performed for 200 individuals (cases), while 100 patients (controls) received direct treatment. One-hundred eighty-five cases had a positive culture (69.7% Gram-negative and 30.3% Gram-positive) and subsequently underwent assessment for antibiotic resistance. Cases comprised more females (56.0%) than controls (48.0%), with no statistically significant differences (p > 0.05). Significantly more patients between 25 and 63 were cases (63.8%) than controls (51.0%), while older ages were notably higher among controls (31.7%; p = 0.044), history of cardiovascular diseases was higher among controls (59.0%) than cases (47.0%; p = 0.050). Escherichia coli (N = 60; 30%), Klebsiella (N = 37; 18.5%), and Streptococcus (N = 32; 16%) were the most common bacteria. The study explored antibiotic resistance patterns among identified germs, emphasizing the high sensitivity of all identified germs for broad-spectrum antibiotics, including meropenem, amikacin, gentamicin, and fluoroquinolones (levofloxacin, ciprofloxacin). High resistance (%Sensitivity below 60%) was noted for Sulfamethoxazole, nalidixic acid, amoxiclav, lincomycin cefotaxime, ceftriaxone, and cefixime. Specifically, Escherichia coli exhibited robust sensitivity to meropenem (100%), amikacin (93.2%), and ciprofloxacin (92.7%). However, notable resistance was observed against sulfamethoxazole (68.8%), amoxicillin-clavulanate (78.3%), and cefotaxime (88.3%). For Klebsiella, resistance rates were prominent, particularly against sulfamethoxazole (69.4%), amoxicillin (83.8%), and nalidixic acid (100%). Among Gram-positive bacteria, Staphylococcus demonstrated significant resistance to sulfamethoxazole (95.2%) and ceftriaxone (78.3%) while maintaining high sensitivity to meropenem (100%) and vancomycin (100%). Streptococcus exhibited notable resistance against sulfamethoxazole (87.5%) and cefotaxime (90.6%).

Conclusion

The increase in resistance to penicillins, sulfonamides, and cephalosporins, along with continued sensitivity to broad-spectrum antibiotics, including aminoglycosides, carbapenems, and fluoroquinolones, emphasizes the importance of promoting antibiogram use and antibiotic stewardship programs. The limited availability of new antibiotics reinforces the need for urgent efforts to optimize antibiotic use and improve clinical outcomes in Northern Syria.

Epidemiology and clinical significance of persistent bacteremia in severely burned patients

BACKGROUND

The utility of follow-up blood cultures (FUBC) for gram-negative bloodstream infections (BSIs) are controversial due to low rates of positivity. However, recent studies suggest higher rates of positivity in critically ill patients. The utility of FUBC in gram-negative BSI in patients with severe burn injuries is unknown.

METHODS

Patients ≥ 18 years old admitted to the US Army Institute of Surgical Research Burn Center for combat-related thermal burns from 1/2003-6/2014 with a monomicrobial BSI were included. FUBC were defined as repeat cultures 1-5 days from index BSI. Persistent BSI (pBSI) was defined as isolation of the same organism from initial and FUBC. The primary endpoint was all-cause in-hospital mortality in patients with gram-negative pBSI.

RESULTS

Of 126 patients meeting inclusion criteria with BSI, 53 (42%) had pBSI. Compared to patients without persistence, patients with pBSI had more severe burns with median total body surface area (TBSA) burns of 47% ([IQR 34-63] vs. 35.3% [IQR 23.3-56.6], p = 0.02), increased mortality (38 vs. 11%, p = 0.001) compared to those with non-persistent BSI. On multivariate analysis, pBSI was associated with an odds ratio for mortality of 5.3 [95% CI 1.8-15.8, p = 0.003). Amongst gram-negative pathogens, persistence rates were high and associated with increased mortality (41% vs. 11%, p = 0.001) compared to patients without pBSI.

CONCLUSION

In this cohort of military patients with combat-related severe burns, pBSI was more common than in other hospitalized populations and associated with increased mortality. Given this high frequency of persistence in patients with burn injuries and associated mortality, FUBC are an important diagnostic and prognostic study in this population.

Persistent gram-negative bloodstream infection increases the risk of recurrent bloodstream infection with the same species

The association between persistent gram-negative bloodstream infection (GN-BSI), or ongoing positive cultures, and recurrent GN-BSI has not been investigated. Among 992 adults, persistent GN-BSI was associated with increased recurrent GN-BSI with the same bacterial species and strain (6% vs 2%; p=0.04). Persistent GN-BSI may be a marker of complicated infection.

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

INTRODUCTION

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Effect of Follow-Up Cerebrospinal Fluid Cultures in Post-Neurosurgical Patients' Outcome with Gram-Negative Bacterial Meningitis/Encephalitis

Background

To investigate the factors associated with follow-up CSF cultures (FUCCs) in post-neurosurgical patients with gram-negative bacterial meningitis/encephalitis and the effect of FUCCs on treatment management and patient outcomes.

Methods

This single-centered retrospective cohort study enrolled post-neurosurgical patients with gram-negative bacterial meningitis/encephalitis at a tertiary-care university hospital between 2012 and 2022. The risk factors for 28-day mortality were evaluated using multivariate Cox analysis. FUCC-related risk factors were also analyzed.

Results

Among the 844 enrolled patients, 504 (59.7%) underwent FUCC, and FUCC was found to be associated with lower rates of both all-cause (hazard ratio (HR) 0.391; 95% confidence interval (CI), 0.235-0.651; p<0.001) and attributable mortality (HR 0.463; 95% CI, 0.239-0.897; p=0.023) in Post-neurosurgical patients diagnosed with Gram-negative bacterial meningitis/encephalitis. Moreover, the results of the study underscored that patients with persistent gram-negative bacterial meningitis/encephalitis had a lower all-cause/attributable short-term survival rate according to 28-day mortality Kaplan-Meier analysis (P=0.001/0.006).

Conclusion

Performing FUCC has been demonstrated to lower mortality rates in Post-neurosurgical patients suffering from Gram-negative bacterial meningitis/encephalitis. The higher mortality rate observed in patients with persistent gram-negative bacterial meningitis/encephalitis suggests that performing FUCC is a crucial component of proper patient care and management, and is therefore recommended for use by clinicians as a standard practice. This finding underscores the significance of consistent implementation of FUCC in the management and prognosis of patients with Post-neurosurgical infections.

Significant Publications on Infectious Diseases Pharmacotherapy in 2022

Purpose: To provide summarization of the most significant infectious diseases (ID) pharmacotherapy articles published in peer-reviewed literature in 2022. Summary: Members of the Houston Infectious Diseases Network (HIDN) nominated notable articles providing significant contributions to ID pharmacotherapy in 2022. Article nominations included those pertaining to general ID, as well as those including coronavirus disease 2019 (COVID-19), and human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) pharmacotherapy. A total of 71 articles were nominated by HIDN. Members: 68 articles pertaining to general ID pharmacotherapy and 3 articles focusing on HIV/AIDS. To aid selection of the most these most notable articles of 2022, a survey was created and distributed to members of the Society of Infectious Diseases Pharmacists (SIDP). Of the 153 SIDP members who participated in the survey, there were 128 recorded votes for the top 10 general ID pharmacotherapy articles and 30 votes recorded for the top HIV/AIDS article. The most notable publications are summarized. Conclusion: Post pandemic significant advances in antimicrobial stewardship and infectious disease states continues to occur in a world recently focused on the coronavirus disease 2019 (COVID-19) global pandemic. Continuous growth in publication of ID-related articles over the past year lends towards the aims of this review to aid clinicians in remaining current on key practice-changing ID pharmacotherapy publications from 2022.

Impact on clinical outcome of follow-up blood cultures and risk factors for persistent bacteraemia in patients with gram-negative bloodstream infections: a systematic review with meta-analysis

BACKGROUND

The clinical usefulness of follow-up blood cultures (FUBCs) in gram-negative bloodstream infections (GN-BSIs) represents a debated issue.

OBJECTIVE

To assess the impact on the clinical outcome of FUBCs in patients with GN-BSI and to predict risk factors for persistent bacteraemia.

DATA SOURCES

PubMed-MEDLINE, Scopus, and the Cochrane Library Database were independently searched until 24 June, 2022.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials, prospective, or retrospective observational studies, including patients affected by GN-BSIs. Primary endpoints were in-hospital mortality rate, and persistent blood stream infections were defined as FUBC-positive for the same pathogen isolated from index blood cultures (BCs).

PARTICIPANTS

Hospitalized patients with documented GN-BSIs.

INTERVENTION

Performance of FUBCs (defined as subsequent BCs collected at least 24 hours after index BCs).

ASSESSMENT OF RISK OF BIAS

Quality of included studies was independently assessed according to the Cochrane Risk of Bias Tool and the Risk Of Bias In Non-randomized Studies of Interventions.

METHODS OF DATA SYNTHESIS

Meta-analysis was performed by pooling odds ratio (OR) retrieved from studies providing adjustment for confounders using random-effect model with the inverse variance method. Risk factors for persistent blood stream infections were also assessed.

RESULTS

A total of 3747 articles were screened, and 11 observational studies (6 assessing impact on outcome (N = 4631), and 5 investigating risk factors for persistent GN-BSI (N = 2566)), conducted between 2002 and 2020 were included. The execution of FUBCs was associated with a significantly lower risk of mortality (OR, 0.58; 95% CI, 0.49-0.70; I2 = 0.0%). The presence of end-stage renal disease (OR, 2.99; 95% CI, 1.77-5.05), central venous catheter (OR, 3.30; 95% CI, 1.82-5.95), infections due to extended-spectrum β-lactamase-producing strains (OR, 2.25; 95% CI, 1.18-4.28), resistance to empirical treatment (OR, 2.70; 95% CI, 1.65-4.41), and unfavourable response at 48 hours (OR, 2.99; 95% CI, 1.44-6.24) emerged as independent risk factors for persistent bacteraemia.

CONCLUSIONS

The execution of FUBCs is associated with a significantly low risk of mortality in patients with GN-BSIs. Our analysis could be useful to stratify patients at a high risk of persistent bacteraemia to optimize the use of FUBCs.

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

BACKGROUND

Gram-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.

METHODS

This 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)).

RESULTS

FUBC 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.

CONCLUSION

Routine FUBC should not be recommended because of the low prevalence of persistent infections in patients under appropriate antibiotic therapy and FUBC increases antibiotic consumption.

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

OBJECTIVE

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.

DESIGN

Retrospective cohort study.

SETTING

The study was conducted in 4 acute-care hospitals in New York City.

PATIENTS

The study included hospitalized adults with GNB bacteremia between 2017 and 2018.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Impact of Persistent Multidrug-Resistant Gram-Negative Bacteremia on Clinical Outcome and Mortality

The clinical aspects of persistent bacteremia (PB) caused by gram-negative rods (GNRs) in terms of antimicrobial resistance (AMR) and PB clearance status are unclear. This secondary analysis of a retrospective cohort study investigated differences in PB caused by Enterobacterales and glucose non-fermentative GNRs (NF-GNRs) based on AMR and PB clearance. We retrospectively surveyed medical records at Tohoku University Hospital. Patients for whom blood cultures were performed between January 2012 and December 2021 were recruited. PB cases were grouped based on AMR and PB clearance; the characteristics of PB due to each bacterial pathogen were examined. The main outcome variable was mortality. The late (30-90-day) mortality rate was significantly higher in the multidrug-resistant (MDR) group than in the non-MDR group for Enterobacterales. However, no significant difference was noted in mortality rates between NF-GNRs with and without AMR. Mortality rates tended to be higher in the non-PB-clearance group than in the clearance group for both Enterobacterales and NF-GNRs. Since the mortality rate was higher in the MDR group in the case of Enterobacterales PB, more careful management is necessary for this condition. Follow-up blood cultures and confirming the clearance of PB are useful for improving the survival rate.

Clearance of blood stream infections in patients receiving extracorporeal membrane oxygenation: a retrospective single-center cohort study

BACKGROUND

There are limited data on the treatment of blood stream infections (BSIs) in patients receiving extracorporeal membrane oxygenation (ECMO). Current guidance recommends documenting clearance only in fungal and Gram-positive BSIs. This study investigates the incidence and clinical significance of blood stream infections with positive repeat cultures (BSIPRC) in ECMO as well as clinical factors that may predict positive repeat cultures.

METHODS

All BSIs in patients receiving ECMO at Brooke Army Medical Center between September 2012 and October 2021 were included in this study. BSIPRC was defined as re-isolation of the same organism on repeat blood cultures following an initial positive blood culture.

RESULTS

A total of 60 patients developed 87 BSI (38.5 BSI per 1000 ECMO days). Of the 80 (92%) BSIs who had repeat blood cultures drawn, patients had BSIPRC in 35 (44%) of cases. Fever, leukocytosis, and vasopressor requirement on day of repeat culture were not associated with persistent positivity. There was no difference in survival to discharge for patients with BSIPRC as compared to single day BSI (58% vs. 63%, p = 0.78). 19% of patients with Gram-negative bacteremia had BSIPRC, and gram-negative bacteremia in general was associated with an 83% morality.

CONCLUSIONS

There were no clinical findings that differentiated patients with BSIPRC from those who had a single day of positivity. BSI was associated with high mortality in patients with Gram-negative bacteremia. Given high incidence of positive repeat cultures being seen in Gram-negative BSIs, repeat blood cultures have utility for all BSIs in patients receiving ECMO.

Clinical and Epidemiological Characteristics of Persistent Bacteremia: A Decadal Observational Study

Background: Bloodstream infections (BSIs), including persistent bacteremia (PB), are a leading source of morbidity and mortality globally. PB has a higher mortality rate than non- PB, but the clinical aspects of PB in terms of the causative pathogens and the presence of clearance of PB are not well elucidated. Therefore, this study aimed to describe the clinical and epidemiological characteristics of PB in a real-world clinical setting. Methods: We performed a retrospective observational survey of patients who underwent blood culture between January 2012 and December 2021 at Tohoku University Hospital. Cases of PB were divided into three groups depending on the causative pathogen: gram-positive cocci (GPC), gram-negative rods (GNRs), and Candida spp. For each group, we examined the clinical and epidemiological characteristics of PB, including differences in clinical features depending on the clearance of PB. The main outcome variable was mortality, assessed as early (30-day), late (30-90 day), and 90-day mortality. Results: Overall, we identified 31,591 cases of single bacteremia; in 6709 (21.2%) cases, the first blood culture was positive, and in 3124 (46.6%) cases, a follow-up blood culture (FUBC) was performed. Of the cases with FUBCs, 414 (13.2%) were confirmed to be PB. The proportion of PB cases caused by Candida spp. was significantly higher (29.6%, 67/226 episodes) than that for GPC (11.1%, 220/1974 episodes, p < 0.001) and GNRs (12.1%, 100/824 episodes, p < 0.001). The Candida spp. group also had the highest late (30-90 day) and 90-day mortality rates. In all three pathogen groups, the subgroup without the clearance of PB tended to have a higher mortality rate than the subgroup with clearance. Conclusions: Patients with PB due to Candida spp. have a higher late (30-90 day) and 90-day mortality rate than patients with PB due to GPC or GNRs. In patients with PB, FUBCs and confirming the clearance of PB are useful to improve the survival rate.

Follow-up blood culture in Gram-negative bacilli bacteraemia: for whom is follow-up blood culture useful?

PURPOSE OF REVIEW

The aim of this narrative review is to examine available evidence about the diagnostic yielding of the follow-up blood cultures (FU-BCs) in patients with Gram-negative bloodstream infection (GN-BSI), the predictors of persistent GN-BSI, and the impact of the performance of FU-BCs on patient management and clinical outcome.

RECENT FINDINGS

The rate of persistent GN-BSI varies from 2.6% to 38.5%, with higher percentages in studies where FU-BCs were obtained from selected patients. Risk factors for persistent GN-BSI were analysed and prediction tools were proposed to guide physicians in the selection of patients. The impact of FU-BCs on patient management is still controversial as several authors have shown that this practice was associated with prolonged treatment duration and longer hospital stay. However, when adjusted for indication and survival bias, the performance of FU-BCs was a strong predictor of survival in large cohorts of hospitalized patients with GN-BSI. Favourable outcome seemed to be associated with higher rate of source control in GN-BSI patients managed with FU-BCs.

SUMMARY

The practice of FU-BCs in patients with GN-BSI should be individualised balancing cost/benefit ratio. The use of risk scores could be useful in selecting patients for whom FU-BCs are appropriate.

Characteristics of bloodstream infection and initial antibiotic use in critically ill burn patients and their impact on patient prognosis

To investigate the bacterial epidemiology of blood cultures taken during the treatment of critically ill burn patients, the use of antibiotics at admission and before the observation of positive blood cultures, and their effect on prognosis. A retrospective study method was used. From January 1, 2010, to December 31, 2019, burn patients who met the inclusion criteria and were treated at the Burn Department, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, were enrolled in the study. Data were collected from the patients' electronic medical records. General patient information, including length of hospital stay, length of intensive care unit (ICU) stay, in-hospital mortality, the bacteria epidemiological characteristics of blood cultures, and the use of antibiotics within 24 h after admission and before a positive blood culture was observed, was collected. Independent sample t tests and χ² tests were used to compare the effects of a positive blood culture and the use of appropriate antibiotics within 24 h after admission and before the observation of a positive blood culture on prognosis. (1) The three most frequently detected bacteria in the blood cultures were Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, and the amount of K. pneumoniae detected increased gradually. (2) Compared with the group of patients who were negative for bloodstream infection , the positive bloodstream infection group had a larger total body burn surface area (TBSA) (t = - 5.097, P = 0.000) and third-degree burn area (t = - 5.133, P = 0.000), a significantly longer length of hospital stay (t = 3.003, P = 0.003) and the length of ICU stay (t = 4.258, P = 0.000), and a significantly higher rate of in-hospital mortality (χ² = 8.485, P = 0.004). When K. pneumoniae was detected, the length of hospital stay (t = 2.148, P = 0.035) and the length of ICU stay (t = 2.880, P = 0.005) were significantly prolonged. (3) The two antibiotics that were most frequently used in patients with acute burns within 24 h after admission were lincomycin (90 cases, 29.32%) and carbapenems (79 cases, 25.73%). Comparing the clinical characteristics of the lincomycin group and the carbapenem group, the TBSA (t = - 3.34, P = 0.001) and the third-degree burn area (t = - 6.08, P = 0.000) of the patients in the carbapenem group were larger, and the length of hospital stay (t = - 2.136, P = 0.035) and length of ICU stay (t = - 5.18, P = 0.000) were longer, but the difference in in-hospital mortality was not statistically significant (χ² = 1.983, P = 0.159). (4) Comparing the group with appropriate initial antibiotic use within 24 h of admission to the inappropriate use group, the TBSA (t = - 0.605, P = 0.547), the third-degree burn area (t = 0.348, P = 0.729), the length of hospital stay (t = - 0.767, P = 0.445), the length of ICU stay (t = - 0.220, P = 0.827) and in-hospital mortality (χ² = 1.271, P = 0.260) were not significantly different. (5) Comparing the group with appropriate antibiotic use before a positive blood culture was observed to the group with inappropriate antibiotic use, the TBSA (t = - 0.418, P = 0.677), the third-degree burn area (t = 0.266, P = 0.791), the length of hospital stay, the length of ICU stay (t = 0.995, P = 0.322) and in-hospital mortality (χ² = 1.274, P = 0.259) were not significantly different. We found that patients with a positive blood culture had a larger burn area and a worse prognosis; that the greater the amount of K. pneumoniae in the bloodstream of burn patients was, the longer the hospital and ICU stays were; that whether appropriate antibiotics were administered to acute critical burn patients 24 h after admission had no effect on the prognosis; and that whether appropriate antibiotics were administered before a positive blood culture was observed had no effect on prognosis.

Association of Repeated Blood Cultures With Mortality in Adult Patients With Gram-Negative Bacilli Bacteremia: A Systematic Review and Meta-analysis

Background

Performing repeat blood cultures after an initial positive culture (ie, follow-up blood cultures [FUBCs]) in patients with gram-negative bacilli (GNB) bacteremia is controversial. We aimed to comprehensively review the association of FUBCs with improvement in patient-relevant clinical outcomes in GNB bacteremia.

Methods

We performed a systematic review and random-effects meta-analysis to calculate summary effect estimates. We used hazard ratios as the effect measure. The primary outcome was 30-day or in-hospital mortality, and secondary outcomes were length of treatment and length of hospital stay. We searched PubMed, Embase, and Cochrane Central Register of Controlled Trials (Central) without language restrictions from inception to April 29, 2022. Original clinical studies evaluating the association between FUBCs and mortality in adult patients with GNB bacteremia were included. FUBC details were reviewed. Two independent reviewers used the Risk of Bias in Non-randomised Studies of Interventions tool.

Results

We identified 9 eligible retrospective studies. In total, 7778 hospitalized patients with GNB bacteremia were included. The studies were clinically heterogeneous and had a critical risk of bias. The utilization of FUBCs varied across studies (18%–89%). Random-effects meta-analysis of covariate-adjusted estimates found that FUBC use was associated with reduced mortality. Although not a result of the meta-analysis, lengths of treatment and hospital stay were longer for patients with FUBCs than for those without. Adverse events were not reported.

Conclusions

FUBC acquisition was associated with lower mortality and longer hospital stay and treatment duration in GNB bacteremia. The risk of bias was critical, and no firm data were available to support mechanisms.

Follow-up blood cultures in Pseudomonas aeruginosa bacteremia: A potential target for diagnostic stewardship

Objectives

Evidence supporting collection of follow-up blood cultures for Gram-negative bacteremia is mixed. We sought to understand why providers order follow-up blood cultures when managing P. aeruginosa bacteremia and whether follow-up blood cultures in this context are associated with short- and long-term survival.

Methods

We conducted a retrospective cohort study of adult inpatients with P. aeruginosa bacteremia at the University of Maryland Medical Center in 2015-2020. Kaplan-Meier survival curves and Cox regression with time-varying covariates were used to evaluate the association between follow-up blood cultures and time to mortality within 30 days of first positive blood culture. Provider justifications for follow-up blood cultures were identified through chart review.

Results

Of 159 eligible patients, 127 (80%) had follow-up blood cultures, including 9 (7%) that were positive for P. aeruginosa and 10 (8%) that were positive for other organisms. Follow-up blood cultures were typically collected "to ensure clearance" or "to guide antibiotic therapy." Overall, 30-day mortality was 25.2%. After risk adjustment for patient characteristics, follow-up blood cultures were associated with a nonsignificant reduction in mortality risk (hazard ratio, 0.43; 95% confidence interval, 1.08; P = .071). In exploratory analyses, the potential mortality reduction from follow-up blood cultures was driven by their use in patients with Pitt bacteremia scores >0.

Conclusions

Follow-up blood cultures are commonly collected for P. aeruginosa bacteremia but infrequently identify persistent bacteremia. Targeted use of follow-up blood cultures based on severity of illness may reduce unnecessary culturing.

Do we need blood culture stewardship programs? A quality control study and survey to assess the appropriateness of blood culture collection and the knowledge and attitudes among physicians in Swiss hospitals

BACKGROUND

Guidance for blood culture (BC) collection is limited. Inappropriate BC collection may be associated with potentially harmful consequences for the patient such as unnecessary laboratory testing, treatment and additional costs. The aim of the study was to assess the appropriateness of BC collection and related knowledge and attitude of precribers.

MATERIALS

We conducted a single-center quality control study to assess the appropriateness of BC collection according to the local guidelines in a Swiss university hospital in 2020 by combining three different approaches: point prevalence, patient-individual longitudinal and diseases-related analysis. Second, we conducted a survey regarding BC collection practices and knowledge among physicians in two non-university and one university hospital using an 18-item electronic questionnaire.

RESULTS

We analyzed 1114 BC collected in 344 patients. Approximately 40% of the BCs were collected inappropriately, in particular in diseases with low pretest probability of bacteremia such as non-severe community acquired pneumonia (CAP). Follow-up blood culture (FUBC) collection was inappropriate in 60%. Growth of a relevant pathogen was more frequently observed in appropriately than in inappropriately collected BCs (18% vs. 3%, p < 0.001). In the survey, uncertainty concerning the need of index BC collection was high in non-severe CAP and uncomplicated cellulitis.

CONCLUSIONS

Almost half of the BCs was not collected according to the guidelines, especially in non-severe CAP and in case of FUBCs. Substantial uncertainty among physicians regarding BC ordering practices was identified. The implementation of diagnostic stewardship programs may improve BC collection practices, increase adherence to local guidelines, and may help reducing unnecessary diagnostics and treatment.

Association of Follow-up Blood Cultures With Mortality in Patients With Gram-Negative Bloodstream Infections: A Systematic Review and Meta-analysis

Importance

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.

Objective

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).

Data Sources

MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Web of Science, and gray literature were searched from inception to March 11, 2022.

Study Selection

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 Extraction and Synthesis

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.

Main Outcomes and Measures

Mortality before hospital discharge or up to 30 days from the index blood culture.

Results

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.

Conclusions and Relevance

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.

Diagnosis and management of infections caused by multidrug-resistant bacteria: guideline endorsed by the Italian Society of Infection and Tropical Diseases (SIMIT), the Italian Society of Anti-Infective Therapy (SITA), the Italian Group for Antimicrobial Stewardship (GISA), the Italian Association of Clinical Microbiologists (AMCLI) and the Italian Society of Microbiology (SIM)

Management of patients with infections caused by multidrug-resistant organisms is challenging and requires a multidisciplinary approach to achieve successful clinical outcomes. The aim of this paper is to provide recommendations for the diagnosis and optimal management of these infections, with a focus on targeted antibiotic therapy. The document was produced by a panel of experts nominated by the five endorsing Italian societies, namely the Italian Association of Clinical Microbiologists (AMCLI), the Italian Group for Antimicrobial Stewardship (GISA), the Italian Society of Microbiology (SIM), the Italian Society of Infectious and Tropical Diseases (SIMIT) and the Italian Society of Anti-Infective Therapy (SITA). Population, Intervention, Comparison and Outcomes (PICO) questions about microbiological diagnosis, pharmacological strategies and targeted antibiotic therapy were addressed for the following pathogens: carbapenem-resistant Enterobacterales; carbapenem-resistant Pseudomonas aeruginosa; carbapenem-resistant Acinetobacter baumannii; and methicillin-resistant Staphylococcus aureus. A systematic review of the literature published from January 2011 to November 2020 was guided by the PICO strategy. As data from randomised controlled trials (RCTs) were expected to be limited, observational studies were also reviewed. The certainty of evidence was classified using the GRADE approach. Recommendations were classified as strong or conditional. Detailed recommendations were formulated for each pathogen. The majority of available RCTs have serious risk of bias, and many observational studies have several limitations, including small sample size, retrospective design and presence of confounders. Thus, some recommendations are based on low or very-low certainty of evidence. Importantly, these recommendations should be continually updated to reflect emerging evidence from clinical studies and real-world experience.

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 (FUBC) in gram-negative (GN) bloodstream infections (BSI) 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 positive FUBC.

Outcomes with Cefiderocol Treatment in Patients with Bacteraemia Enrolled into Prospective Phase 2 and Phase 3 Randomised Clinical Studies

Introduction

A post hoc, descriptive analysis of three prospective, randomised, controlled clinical studies investigating cefiderocol in gram-negative bacterial infections was conducted to assess its efficacy in patients with baseline bacteraemia.

Methods

Data from APEKS-cUTI (NCT02321800), APEKS-NP (NCT03032380) and CREDIBLE-CR (NCT02714595) studies were assessed individually. Patients received cefiderocol 2g, q8h, for 7–14 days or comparators (imipenem/cilastatin [APEKS-cUTI], meropenem [APEKS-NP] or best available therapy [BAT; CREDIBLE-CR]). Bacteraemia and clinical outcomes were assessed at early assessment (EA), end of treatment (EOT) and test of cure (TOC) for patients in the intention-to-treat populations with baseline blood samples positive for aerobic gram-negative species. Eradication, persistence or recurrence of baseline blood pathogen was confirmed from follow-up blood cultures; in the absence of follow-up blood cultures, clinical response, administration of additional antibiotics and vital status were used to assess bacteraemia outcome.

Results

Of 885 patients randomised, 84 had bacteraemia and 89 (cefiderocol: 55, comparators: 34) gram-negative pathogens were isolated, namely Enterobacterales (n = 62) and non-fermenters (n = 27). At EA, on-therapy bacteraemia eradication rates in APEKS-cUTI, APEKS-NP and CREDIBLE-CR were 100% (19/19), 50.0% (4/8) and 72.0% (18/25) with cefiderocol. Corresponding rates for comparators were 77.8% (7/9), 100% (10/10) and 69.2% (9/13), respectively. Persistence in blood at EA was seen in six patients overall (cefiderocol: 3, comparators: 3); indeterminate responses were common (cefiderocol: 8, comparators: 3), usually due to lack of blood cultures. Clinical cure/improvement rates at EA in APEKS-cUTI, APEKS-NP and CREDIBLE-CR were 100% (19/19), 62.5% (5/8) and 64.0% (16/25) with cefiderocol. Corresponding rates for comparators were 77.8% (7/9), 90.0% (9/10) and 30.8% (4/13), respectively. Bacteraemia eradication rates with cefiderocol in APEKS-cUTI, APEKS-NP and CREDIBLE-CR were 89.5%, 37.5% and 60.0% at EOT and 78.9%, 12.5% and 44.0% at TOC.

Conclusion

This descriptive analysis suggests that cefiderocol may be a useful treatment option for gram-negative bacteraemia, including pathogens resistant to other antibiotics.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-022-00598-9.

Microbiology Assessments in Critically Ill Patients

The prevalence of suspected or proven infections in critically ill patients is high, with a substantial attributable risk to in-hospital mortality. Coordinated guidance and interventions to improve the appropriate microbiological assessment for diagnostic and therapeutic decisions are therefore pivotal. Conventional microbiology follows the paradigm of "best practice" of specimen selection and collection, governed by laboratory processing and standard operating procedures, and informed by the latest developments and trends. In this regard, the preanalytical phase of a microbiological diagnosis is crucial since inadequate sampling may result in the incorrect diagnosis and inappropriate management. In addition, the isolation and detection of contaminants interfere with multiple intensive care unit (ICU) processes, which confound the therapeutic approach to critically ill patients. To facilitate bedside enablement, the microbiology laboratory should provide expedited feedback, reporting, and interpretation of results. Compared with conventional microbiology, novel rapid and panel-based diagnostic strategies have the clear advantages of a rapid turnaround time, the detection of many microorganisms including antimicrobial resistant determinants and thus promise substantial improvements in health care. However, robust data on the clinical evaluation of rapid diagnostic tests in presumed sepsis, sepsis and shock are extremely limited and more rigorous intervention studies, focusing on direct benefits for critically ill patients, are pivotal before widespread adoption of their use through the continuum of ICU stay. Advocating the use of these diagnostics without firmly establishing which patients would benefit most, how to interpret the results, and how to treat according to the results obtained, could in fact be counterproductive with regards to diagnostic "best practice" and antimicrobial stewardship. Thus, for the present, they may supplement but not yet supplant conventional microbiological assessments.

Unresolved issues in the epidemiology and diagnosis of bacteremia: an opinion paper

Bacteremia is an important cause of morbidity and mortality worldwide and, despite the diagnostic and therapeutic advances of the last decades, the evidence supporting many diagnostic aspects of bacteremia is scarce. Information on the epidemiological evolution of this entity is limited and many methodological aspects of blood culture collection and analysis are under discussion. Furthermore, the recommendations of the main scientific societies on many of these aspects are variable and, in many cases, have not been updated recently. In this scenario, we have arranged a series of questions on different aspects of bacteremia and reviewed the literature trying to find proper answers for them. We offer our opinion on the topics where the evidence was weak. The topics covered include epidemiological aspects of bacteremia, indications for blood culture extraction, methods for obtaining and incubating samples, or ways of transmitting results from the microbiology laboratory. We do not intend to summarize the current clinical practice guidelines, nor will we deal with the therapeutic management of this entity. The aim of this paper is to review the current perspective on the diagnosis of bacteremia with a critical approach, to point out the gaps in the literature, to offer the opinion of a team dedicated to infectious diseases and clinical microbiology, and to identify some areas of knowledge on which future studies should focus.

OUP accepted manuscript

Background

Trials supporting shorter durations of antibiotic therapy for Gram-negative bloodstream infections (GN-BSI) have recently been published. However, adoption of these findings into practice is unclear given limited eligibility criteria and relatively large non-inferiority margins of these studies. To better understand contemporary management of GN-BSI, we conducted an international survey of infectious diseases (ID) specialists.

Methods

We developed and disseminated an online survey to assess practice patterns involving treatment duration of GN-BSI, including providers from 28 countries. χ² tests, t-tests and multivariable linear regression with generalized estimating equations were used to identify factors associated with treatment duration.

Results

In total, 277 ID specialists completed the survey (64% physicians, 31% pharmacists). The median reported duration of antibiotics was 7 days (IQR, 7–10 days) for all GN-BSI sources. Thirty percent of providers typically recommend durations that differ by ≥7 days depending on the source of GN-BSI, and 71% treat ≥10 days for at least one source. In an adjusted model, factors associated with increased duration included intra-abdominal (+1.01 days, 95% CI 0.57–1.45 days; P < 0.0001), vascular catheter (+0.74 days; 0.33–1.15 days; P = 0.0004), and respiratory (+0.76 days; 0.38–1.14 days; P < 0.0001) sources of GN-BSI relative to urinary sources. Providers that transition patients to oral therapy report shorter durations than those who treat with full IV therapy (−0.60 days; −1.12 to −0.09 days; P = 0.02).

Conclusions

There is extensive heterogeneity in duration of therapy for treating GN-BSI, particularly with respect to source of GN-BSI. Investigations into appropriate treatment durations for different GN-BSI sources are needed.

New evidence for managing Gram-negative bloodstream infections

PURPOSE OF REVIEW

Gram-negative bloodstream infections (GNBSI) are common and carry considerable mortality. Treatment is complicated by increasing antimicrobial resistance, posing a challenge for timely appropriate antibiotics and limiting the choices of effective definitive therapy. The present review aims to summarize recent studies addressing the management of GNBSI.

RECENT FINDINGS

New rapid diagnostic tests (RDT) for pathogen identification and antibiotic susceptibility are associated with improved antimicrobial stewardship and reduced length of stay. No mortality benefit or patient-related outcomes are reported. Data regarding the use of new beta-lactam beta-lactamase inhibitors (BLBLIs) for treating multidrug resistance Gram-negative bacteria is supportive, though questions regarding combinations, optimal dosing, mode of administration, and resistance emergence remain to be clarified. Current data regarding cefiderocol necessitates further studies in order to support its use in GNBSI. Shortened (≤7 days) duration of therapy and early oral step down for GNBSI are supported by the literature. The role of repeated blood cultures should be further defined.

SUMMARY

RDTs should be implemented to improve antibiotic stewardship. Clinical implications on patient-related outcomes should be evaluated. New BLBLIs show promise in the treatment of GNBSI. Additional data are needed regarding the use of cefiderocol. Antibiotic therapy should be shortened and early oral step down should be considered.

Optimizing the Management of Uncomplicated Gram-Negative Bloodstream Infections: Consensus Guidance Using a Modified Delphi Process

Background

Guidance on the recommended durations of antibiotic therapy, the use of oral antibiotic therapy, and the need for repeat blood cultures remain incomplete for gram-negative bloodstream infections. We convened a panel of infectious diseases specialists to develop a consensus definition of uncomplicated gram-negative bloodstream infections to assist clinicians with management decisions.

Methods

Panelists, who were all blinded to the identity of other members of the panel, used a modified Delphi technique to develop a list of statements describing preferred management approaches for uncomplicated gram-negative bloodstream infections. Panelists provided level of agreement and feedback on consensus statements generated and refined them from the first round of open-ended questions through 3 subsequent rounds.

Results

Thirteen infectious diseases specialists (7 physicians and 6 pharmacists) from across the United States participated in the consensus process. A definition of uncomplicated gram-negative bloodstream infection was developed. Considerations cited by panelists in determining if a bloodstream infection was uncomplicated included host immune status, response to therapy, organism identified, source of the bacteremia, and source control measures. For patients meeting this definition, panelists largely agreed that a duration of therapy of ~7 days, transitioning to oral antibiotic therapy, and forgoing repeat blood cultures, was reasonable.

Conclusions

In the absence of professional guidelines for the management of uncomplicated gram-negative bloodstream infections, the consensus statements developed by a panel of infectious diseases specialists can provide guidance to practitioners for a common clinical scenario.

Neither Blood Culture Positivity nor Time to Positivity Is Associated With Mortality Among Patients Presenting With Severe Manifestations of Sepsis: The FABLED Cohort Study

Background

Sepsis is a leading cause of morbidity, mortality, and health care costs worldwide.

Methods

We conducted a multicenter, prospective cohort study evaluating the yield of blood cultures drawn before and after empiric antimicrobial administration among adults presenting to the emergency department with severe manifestations of sepsis. Enrolled patients who had the requisite blood cultures drawn were followed for 90 days. We explored the independent association between blood culture positivity and its time to positivity in relation to 90-day mortality.

Results

Three hundred twenty-five participants were enrolled; 90-day mortality among the 315 subjects followed up was 25.4% (80/315). Mortality was associated with age (mean age [standard deviation] in those who died was 72.5 [15.8] compared with 62.9 [17.7] years among survivors; P < .0001), greater Charlson Comorbidity Index (2 [interquartile range {IQR}, 1–3] vs 1 [IQR, 0–3]; P = .008), dementia (13/80 [16.2%] vs 18/235 [7.7%]; P = .03), cancer (27/80 [33.8%] vs 47/235 [20.0%]; P = .015), positive quick Sequential Organ Failure Assessment score (57/80 [71.2%] vs 129/235 [54.9%]; P = .009), and normal white blood cell count (25/80 [31.2%] vs 42/235 [17.9%]; P = .02). The presence of bacteremia, persistent bacteremia after antimicrobial infusion, and shorter time to blood culture positivity were not associated with mortality. Neither the source of infection nor pathogen affected mortality.

Conclusions

Although severe sepsis is an inflammatory condition triggered by infection, its 90-day survival is not influenced by blood culture positivity nor its time to positivity.

Clinical Trials Registration

NCT01867905.

Bacteremia in solid organ transplant recipients as compared to immunocompetent patients: Acute phase cytokines and outcomes in a prospective, matched cohort study

We undertook a prospective, matched cohort study of patients with Staphylococcus aureus bacteremia (SAB) and gram-negative bacteremia (GNB) to compare the characteristics, outcomes, and chemokine and cytokine response in transplant recipients to immunocompetent, nontransplant recipients. Fifty-five transplant recipients (GNB n = 29; SAB n = 26) and 225 nontransplant recipients (GNB n = 114; SAB n = 111) were included for clinical analysis. Transplant GNB had a significantly lower incidence of septic shock than nontransplant GNB (10.3% vs 30.7%, p = .03). Thirty-day mortality did not differ significantly between transplant and nontransplant recipients with GNB (10.3% vs 15.8%, p = .57) or SAB (0.0% vs 11.7%, p = .13). Next, transplant patients were matched 1:1 with nontransplant patients for the chemokine and cytokine analysis. Five cytokines and chemokines were significantly lower in transplant GNB vs nontransplant GNB: IL-2 (median [IQR]: 7.1 pg/ml [7.1, 7.1] vs 32.6 pg/ml [7.1, 88.0]; p = .001), MIP-1β (30.7 pg/ml [30.7, 30.7] vs 243.3 pg/ml [30.7, 344.4]; p = .001), IL-8 (32.0 pg/ml [5.6, 53.1] vs 59.1 pg/ml [39.2, 119.4]; p = .003), IL-15 (12.0 pg/ml [12.0, 12.0] vs 12.0 pg/ml [12.0, 126.7]; p = .03), and IFN-α (5.1 pg/mL [5.1, 5.1] vs 5.1 pg/ml [5.1, 26.3]; p = .04). Regulated upon Activation, Normal T Cell Expressed and Secreted (RANTES) was higher in transplant SAB vs nontransplant SAB (mean [SD]: 750.2 pg/ml [194.6] vs 656.5 pg/ml [147.6]; p = .046).

Incidence and utility of follow-up blood cultures in cancer patients with gram-negative bacteremia

Benefit of follow-up blood cultures (FUBC) in cancer patients with gram-negative bacteremia (GNB) is unknown. Multicenter, retrospective review was performed in adult cancer patients with GNB between January and December 2018. Primary outcome was FUBC incidence. Chi-square, t-tests/Wilcoxon rank-sum, and bivariate regression (logistic/Poisson) analyses compared secondary outcomes (catheter removal, ID consultation, antibiotic duration, length stay, mortality) between patients with versus without FUBC. Of 52 patients with GNB, majority (35/52; 67%) received ≥1 FUBC (mean per patient 3.6, SD 4.3, range 0-29). Majority FUBC had no growth (157/173; 90.8%). Rates of catheter removal and ID consultation were similar between groups (P > 0.05). Patients with FUBC had greater LOS (mean 21 vs 15 days; coefficient = 0.31, CI 0.17-0.45), longer duration of antibiotics (mean 13 vs 11 days, coefficient 0.19, P = 0.013), but no mortality difference (P = 1). FUBC are frequently performed yet infrequently positive in cancer patients with GNB, but were associated with increased LOS and antibiotic duration.

Impact of follow up blood cultures on outcomes of patients with community-onset gram-negative bloodstream infection

BACKGROUND

The role of follow up blood cultures (FUBC) in the management of gram-negative bloodstream infection (GN-BSI) remains controversial. This retrospective cohort study examines the association between obtaining FUBC and mortality in GN-BSI.

METHODS

Hospitalized adults with community-onset GN-BSI at Prisma Health-Midlands hospitals in South Carolina, USA from January 1, 2010 to June 30, 2015 were identified. Patients who died or were discharged from hospital within 72 h were excluded to minimize impact of survival and selection biases on results, respectively. Multivariate Cox proportional hazards regression was used to examine association between obtaining FUBC and 28-day all-cause mortality after adjustment for the propensity to obtain FUBC.

FINDINGS

Among 766 patients with GN-BSI, 219 (28.6%) had FUBC obtained and 15 of 219 (6.8%) FUBC were persistently positive. Overall, median age was 67 years, 438 (57%) were women, 457 (60%) had urinary source of infection, and 426 (56%) had BSI due to Escherichia coli. Mortality was significantly lower in patients who had FUBC obtained than in those who did not have FUBC (6.3% vs. 11.7%, log-rank p = 0.03). Obtaining FUBC was independently associated with reduced mortality (hazards ratio 0.47, 95% confidence intervals: 0.23-0.87; p = 0.02) after adjustments for age, chronic comorbidities, acute severity of illness, appropriateness of empirical antimicrobial therapy, and propensity to obtain FUBC.

INTERPRETATION

Improved survival in hospitalized patients with GN-BSI who had FUBC is consistent with the results of recent publications from Italy and North Carolina supporting utilization of FUBC in management of GN-BSI.

FUNDING

This study had no funding source.

Quality of care indicators in the MAnageMent of BlOOdstream infections caused by Enterobacteriaceae (MAMBOO-E study): state of the art and research agenda

OBJECTIVES

The impact on outcome of five interventions was reviewed in order to investigate the state of the art for management of Enterobacteriaceae bloodstream infection (E-BSI).

METHODS

We searched for randomised controlled trials (RCTs) and observational studies published from January 2008 to March 2019 in PubMed, EMBASE and Cochrane Library. Populations consisted of patients with E-BSI. Interventions were as follows: (i) performance of imaging to assess BSI source and/or complications; (ii) follow-up blood cultures (FU-BCs); (iii) use of loading dose followed by extended/continuous infusion (E/CI) of β-lactams; (iv) duration of treatment (short- versus long-term); and (v) infectious diseases (ID) consultation. Patients without intervention were considered as controls. The main outcome was 30-day mortality. RoB 2.0 and ROBINS-I tools were used for bias assessment.

RESULTS

No study was eligible for interventions i, iii and v. For FU-BCs, one observational study including 901 patients with E-BSI was considered. Intervention consisted of repeating BCs within 2-7 days after index BCs. All-cause 30-day mortality was 14.2% (35/247) in the intervention group versus 14.7% (96/654) in the control group. For short treatment duration, two RCTs and six observational studies were included comprising 4473 patients with E-BSI. All-cause mortality was similar in the short and long treatment groups (OR = 1.10, 95% CI 0.83-1.44).

CONCLUSION

Of the assessed interventions, only short treatment duration in non-immunocompromised patients with E-BSI is supported by current data. Studies investigating the use of systematic imaging, FU-BCs, E/CI β-lactams and ID consultation in patients with E-BSI are needed.

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 ≥ 18 years 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.

Are Follow-Up Blood Cultures Useful in the Antimicrobial Management of Gram Negative Bacteremia? A Reappraisal of Their Role Based on Current Knowledge

Bloodstream infections still constitute an outstanding cause of in-hospital morbidity and mortality, especially among critically ill patients. Follow up blood cultures (FUBCs) are widely recommended for proper management of Staphylococcus aureus and Candida spp. infections. On the other hand, their role is still a matter of controversy as far as Gram negative bacteremias are concerned. We revised, analyzed, and commented on the literature addressing this issue, to define the clinical settings in which the application of FUBCs could better reveal its value. The results of this review show that critically ill patients, endovascular and/or non-eradicable source of infection, isolation of a multi-drug resistant pathogen, end-stage renal disease, and immunodeficiencies are some factors that may predispose patients to persistent Gram negative bacteremia. An analysis of the different burdens that each of these factors have in this clinical setting allowed us to suggest which patients’ FUBCs have the potential to modify treatment choices, prompt an early source control, and finally, improve clinical outcome.

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.