Single Positive Blood Culture Research Articles

Management of infectious endocarditis from the perspective of the Infectious Diseases specialist – a 2023 update

An increase in the number and the complexity of cardiac surgery has brought on a rise in the proportion of healthcare-associated Infectious Endocarditis (IE), and as a result, today S. aureus is the most common causative pathogen for this condition. Clinical suspicion for IE should be raised in front of a patient with predisposing risk factors, a new heart murmur and/or vasculitic/embolic events. The Duke Criteria have been long used to diagnose IE. However, they underwent several changes in order to improve their sensitivity in the diagnosis of Q-fever IE and to decrease the size of the possible IE group. Our primary goal is to enhance the knowledge regarding the diagnosis and treatment of infective endocarditis. In acute IE, prior to beginning antibiotic therapy, at least three sets of blood cultures must be taken, ideally from three distinct sites, as determining the etiologic agent is of highest importance. The diagnosis of IE cannot be made based just on a single positive blood culture. To diagnose subacute IE, three to five sets of blood cultures must be drawn over the course of 24 hours. Transthoracic echocardiography (TTE) remains the preferred investigation when the diagnosis of IE is suspected. Transesophageal echocardiography (TOE) is recommended when TTE is unremarkable but the suspicion is still high. A whole-body CT scan, an MRI, a cardiac CT, PET-CT, or radiolabeled leucocyte single-photon emission computed tomography may be helpful when TTE and TOE are inconclusive. Recommended empirical therapy for Native Valve Endocarditis (NVE) and late Prosthetic Valve Endocarditis (PVE) consists of IV Amoxicillin, Oxacillin and Gentamicin administered until blood culture results are available. If a patient is allergic to penicillin, IV Vancomycin and Gentamicin should be given. The recommended empirical antibiotic regimen for early PVE includes IV Vancomycin, Gentamicin, and Rifampin. Once the results of blood cultures are available, the treatment will depend on the isolated organism, its sensitivity to antibiotics, and whether it is an NVE or a PVE.

The effect of duration of antimicrobial treatment for bacteremia in critically ill patients on in-hospital mortality – Retrospective double center analysis

PurposeExcessive duration of antibiotic treatment is a major factor for inappropriate antibiotic consumption. Although in some instances shorter antibiotic courses are as efficient as longer ones, no specific recommendations as to the duration of antimicrobial treatment for bloodstream infections currently exist. In the present study, we investigated the effect of antibiotic treatment duration on in-hospital mortality using retrospective data from two cohorts that included patients with bacteremia at two Swiss tertiary Intensive Care Units (ICUs). Materials and methodsOverall 8227 consecutive patients requiring ICU admission were screened for bacteremia between 01/2012–12/2013 in Lausanne and between 07/2016–05/2017 in Bern. Patients with an infection known to require prolonged treatment or having single positive blood culture with common contaminant pathogens were excluded. The primary outcome of interest was the time from start of antimicrobial treatment to in-hospital death or hospital discharge, whichever comes first. The predictor of interest was adequate antimicrobial treatment duration, further divided into shorter (≤10 days) and longer (>10 days) durations. A time-dependent Cox model and a cloning approach were used to address immortality bias. The secondary outcomes were the median duration of antimicrobial treatment for patients with bacteremia overall and stratified by underlying infectious syndrome and pathogens in the case of secondary bacteremia. ResultsOut of the 707 patients with positive blood cultures, 382 were included into the primary analysis. Median duration of antibiotic therapy was 14 days (IQR, 7–20). Most bacteremia (84%) were monomicrobial; 18% of all episodes were primary bacteremia. Respiratory (28%), intra-abdominal (23%) and catheter infections (17%) were the most common sources of secondary bacteremia. Using methods to mitigate the risk of confounding associated with antibiotic treatment durations, shorter versus longer treatment groups showed no differences in in-hospital survival (time-dependent Cox-model: HR 1.5, 95% CI (0.8, 2.7), p = 0.20; Cloning approach: HR 1.0, 95% CI (0.7,1.5) p = 0.83). Sensitivity analyses showed that the interpretation did not change when using a 7 days cut-off. ConclusionsIn this restrospective study, we found no evidence for a survival benefit of longer (>10 days) versus shorter treatment course in ICU patients with bacteremia. Trial registrationThe study was retrospectively registered on clinicatrials.gov (NCT05236283), 11 February 2022. The respective cantonal ethics commission (KEK Bern # 2021–02302) has approved the study.

Staphylococcus lugdunensis bacteremia: clinical implications of single set positive blood cultures

Staphylococcus lugdunensis is exceptionally virulent among the coagulase-negative Staphylococcus species, but the clinical significance of single-positive bacteremia of S. lugdunensis remains uncertain. We investigated S. lugdunensis bacteremia cases over 10 years. Of the 49 cases included, 12 had multiple-positive blood cultures and 37 had single-positive blood cultures. Antimicrobial therapy was given to over 80% of both groups, whereas the duration of therapy was significantly longer in the multiple-positive group. The overall 30-day and 90-day mortality rates were 13.3% and 18.2%, and 36.7% and 18.2% for single and multiple-positive patients, respectively. Five single-positive patients without therapy did not have severe infection, presumed source of infection, or culture positivity within 20 hours, but all defervesced within 2 days and were alive at 30 days. While the clinical spectrum of single-positive S. lugdunensis bacteremia is broad, antimicrobial therapy may be withheld without adverse clinical consequences in a subset of low-risk patients.

Culture-based determinants and outcome of Staphylococcus aureus bloodstream infections

The objective of this study was to examine the occurrence, determinants, and outcome of S. aureus bloodstream infections (BSI) diagnosed based on single versus multiple positive initial cultures. All adults with first episodes of mono-microbial S. aureus BSI in Queensland during 2000-2019 were included. 10,855 (67%) and 5,421 (33%) were diagnosed based on one and multiple positive initial cultures, respectively. Patients with multiple positive initial cultures were significantly younger, more likely to have community-associated disease, have a shorter time to culture positivity, less likely to have methicillin-resistant S. aureus BSI, and have a different distribution of comorbid medical illnesses and clinical foci. The 30-day all-cause case-fatality rate was 18% and single positive initial culture was an independent risk factor for death. Among patients with S. aureus BSI, those diagnosed by single positive initial blood cultures have different clinical features and a higher risk for death.

Early warning for healthcare acquired infections in neonatal care units in a low-resource setting using routinely collected hospital data: The experience from Haiti, 2014-2018.

In low-resource settings, detection of healthcare-acquired outbreaks in neonatal units relies on astute clinical staff to observe unusual morbidity or mortality from sepsis as microbiological diagnostics are often absent. We aimed to generate reliable (and automated) early warnings for potential clusters of neonatal late onset sepsis using retrospective data that could signal the start of an outbreak in an NCU in Port au Prince, Haiti, using routinely collected data on neonatal admissions. We constructed smoothed time series for late onset sepsis cases, late onset sepsis rates, neonatal care unit (NCU) mortality, maternal admissions, neonatal admissions and neonatal antibiotic consumption. An outbreak was defined as a statistical increase in any of these time series indicators. We created three outbreak alarm classes: 1) thresholds: weeks in which the late onset sepsis cases exceeded four, the late onset sepsis rates exceeded 10% of total NCU admissions and the NCU mortality exceeded 15%; 2) differential: late onset sepsis rates and NCU mortality were double the previous week; and 3) aberration: using the improved Farrington model for late onset sepsis rates and NCU mortality. We validated pairs of alarms by calculating the sensitivity and specificity of the weeks in which each alarm was launched and comparing each alarm to the weeks in which a single GNB positive blood culture was reported from a neonate. The threshold and aberration alarms were the strongest predictors for current and future NCU mortality and current LOS rates (p<0.0002). The aberration alarms were also those with the highest sensitivity, specificity, negative predictive value, and positive predictive value. Without microbiological diagnostics in NCUs in low-resource settings, applying these simple algorithms to routinely collected data show great potential to facilitate early warning for possible healthcare-acquired outbreaks of LOS in neonates. The methods used in this study require validation across other low-resource settings.

Bloodstream infections in hospitalized patients before and during the COVID-19 surge in a community hospital in the South Bronx

Bloodstream infections in hospitalized patients before and during the COVID-19 surge in a community hospital in the South Bronx

Clinical Significance of Staphylococcus aureus in a Single Positive Blood Culture Bottle.

Clinical significance of a single positive blood culture bottle (SPBCB) with Staphylococcus aureus is unclear. We aimed to assess the significance of an SPBCB by looking at the associated outcomes. We performed a retrospective, multicenter study of patients with an SPBCB with S aureus using data collected from both electronic health records and the clinical microbiology laboratory. Overall, 534 patients with S aureus bacteremia were identified and 118 (22.1%) had an SPBCB. Among cases with an SPBCB, 106 (89.8%) were classified as clinically significant whereas 12 (10.2%) were considered contaminated or of unclear significance. A majority (92.4%) of patients received antibiotic therapy, but patients with clinically significant bacteremia were treated with longer courses (25.9 vs 5.7 days, P < .001). Significant differences in both frequency of echocardiography (65.1% vs 84.6%, P < .001) and infective endocarditis diagnosis (3.8% vs 14.2%, P = .002) were seen in those with an SPBCB compared to those with multiple positive bottles. A longer hospital length of stay and higher 90-day, 6-month, and 1-year mortality rates were seen in patients with multiple positive blood culture bottles. An SPBCB with S aureus was common among our patients. While this syndrome has a more favorable prognosis as compared to those with multiple positive blood cultures, clinicians should remain concerned as it portends a risk of infective endocarditis and mortality.

6. Staphylococcus aureus in a Single Blood Culture Bottle: Should We be Concerned?

Background Staphylococcus aureus bacteremia (SAB) is common and is characterized by high rates of morbidity and mortality. The clinical importance of a single positive blood culture bottle (SPBCB), however, is poorly defined despite it being a frequent laboratory finding. We therefore examined patients with SPBCB to determine its clinical significance and to understand the rationale of current practice.MethodsWe performed a retrospective, multicenter study of patients with a SPBCB for S. aureus in initial cultures from January 2019 to December 2019 using data collected from both electronic health records and the clinical microbiology laboratory. ResultsOverall, 534 patients with SAB were identified, and 118 (22.1%) had a SPBCB. Among SPBCB cases, 106 (89.3%) were classified as clinically significant while 12 were considered contaminated or of unclear clinical significance. Baseline characteristics were similar between the groups (Table 1). A majority (92.4%) received antibiotic therapy, but patients with clinically significant bacteremia were treated with a longer antibiotic course (25.9 vs 5.7 days, p< 0.001). Outcomes between those with SPBCB (contaminant vs clinically significant) were similar (Table 2). Of note, while there was no difference in use of echocardiography based on PREDICT criteria between the clinically significant SPBCB vs. the multiple positive blood culture bottles (MPBC) cohorts (Table 3), significant differences were seen in both frequency of echocardiography (65.1% vs. 84.6%, P< 0.001) and IE diagnosis (3.8% vs. 14.2%, P=0.002) for patients in the SPBCB vs. MPBC groups, respectively. In addition, those with MPBC had higher 90-day, 6-month and 1-year mortality rates. ConclusionSPBCB was documented in almost one-quarter of SAB cases and should trigger a thorough investigation as its associated mortality was high and complications, including IE, occurred. Although some SPBCB cases may represent contamination, antibiotic treatment of SPBCB was commonplace. Patients with clinically significant SPBCB were less likely to undergo echocardiography and had a reduced prevalence of an IE diagnosis as compared to those with MPBC. Patients with SPBCB may have a more favorable long-term prognosis as compared to that in patients with MPBC. Disclosures Muhammad R. Sohail, MD, Medtronic (Consultant)Philips (Consultant) Larry M. Baddour, MD, Boston Scientific (Individual(s) Involved: Self): Consultant; Botanix Pharmaceuticals (Individual(s) Involved: Self): Consultant; Roivant Sciences (Individual(s) Involved: Self): Consultant

Determinants and outcomes of bloodstream infection in adults associated with one versus two sets of positive index blood cultures

ObjectivesTo investigate whether positivity in one or both index sets of blood cultures influences clinical determinants and mortality when diagnosing bloodstream infections (BSI). MethodsRetrospective population-based surveillance of all mono-microbial BSI was conducted among residents of the western interior of British Columbia. Clinical details were obtained by chart review and all-cause case-fatality was established at 30 days. Index cultures were defined as the first two sets of cultures initially drawn to diagnose incident BSI. ResultsA total of 2500 incident BSI were identified of which 945 (37.8%) and 1555 (62.2%) were based on one and two positive index cultures, respectively. There was an overall difference in the distribution of pathogens, with both Staphylococcus aureus and Streptococcus pneumoniae more likely to have two positive index cultures. Different foci of infection were associated with one versus two positive index cultures. Overall, 409 patients died within 30 days of index BSI for an all-cause case-fatality of 16.4%; with no difference between two positive (250/1555; 16.1%) and one positive (159/945; 16.8%; p 0.3) index blood culture. The number of positive index blood cultures was not associated with 30-day case-fatality after adjustment for confounding variables using logistic regression analysis. ConclusionsAlthough approximately one-third of BSI are diagnosed on the basis of a single positive blood culture and are associated with different clinical determinants, whether one or both index blood cultures are positive is not associated with lethal outcome.

1336. Alcohol Impregnated Caps and Ambulatory CLABSI: Multicenter Cluster Randomized, Crossover Trial

BackgroundCentral line-associated bloodstream infections (CLABSI) cause significant morbidity and mortality and occur more commonly in the ambulatory setting in pediatric oncology patients. Whether alcohol impregnated caps placed on central venous lines can prevent CLABSI in ambulatory pediatric oncology patients is unknown.MethodsWe performed a cluster-randomized, 2 period, crossover trial at 16 pediatric hematology/oncology clinics. Clinics were randomly assigned to usual ambulatory central line care per each institution (control) compared to use of 70% isopropyl alcohol-containing caps at home (intervention). Caps were only used in the ambulatory setting. The primary outcome was ambulatory CLABSI. Secondary outcomes included ambulatory mucosal barrier injury (MBI) CLABSI, secondary blood stream infections, single positive blood cultures, and positive blood cultures.ResultsOf the 16 participating clinics, 15 clinics completed both assignment periods. As assigned, there was no statistically significant reduction in incidence of ambulatory CLABSI in patients using 70% isopropyl alcohol-impregnated caps at home (1.23 per 1000 days, 95% CI 0.94, 1.60) compared with standard practices (1.38 per 1000 days, 95% CI 1.08, 1.77; adjusted incidence rate ratio [aIRR] 0.83, 95% CI 0.61, 1.12). There was no reduction in incidence of ambulatory MBI-CLABSI (aIRR 0.57, 95% CI 0.23, 1.40), single positive blood culture (aIRR 1.35, 95% CI 0.74, 2.48), or positive blood cultures (aIRR 0.80, 95% CI 0.60, 1.07). In the per protocol analysis, there was a reduction in incidence of positive blood cultures in ambulatory patients using 70% isopropyl alcohol-impregnated caps at home (1.51 per 1000 days, 95% CI 1.14, 2.00) compared with standard practices (1.88 per 1000 days, 1.47, 2.39; aIRR 0.72, 95% CI 0.51, 1.00).ConclusionIsopropyl alcohol- impregnated caps did not lead to a statistically significant reduction in CLABSI rates in ambulatory hematology/oncology patients, however, there was a reduction in positive blood cultures in the ambulatory setting in the per protocol analysis. Further research is needed to understand the clinical impact of alcohol-impregnated caps in the ambulatory setting.Disclosures All Authors: No reported disclosures

579. Machine-Learning Based Models for Prediction of Recurrence-free Catheter Retention After ALT Treatment of CLABSI in a Pediatric Population

BackgroundDeciding whether to attempt salvage of an infected central venous catheter (CVC) can be challenging. While line removal is the definitive treatment for central-line associated bloodstream infection (CLABSI), salvage may be attempted with systemic antibiotics and antibiotic lock therapy (ALT). Weighing risk and benefit of CVC salvage is limited by uncertainty in the future viability of salvaged CVCs. If a CVC is likely to require subsequent removal (e.g., due to recurrent infection) salvage may not be beneficial, whereas discarding a viable CVC is also not desirable. Here we describe a machine learning approach to predicting outcomes in CVC salvage.MethodsEpisodes of pediatric CLABSI cleared with ALT were identified by retrospective record review between January 1, 2008 and December 31, 2018 and were defined by a single positive central blood culture of a known pathogen or two matching cultures of a possible contaminant. Clearance was defined as 48-hours of negative cultures and relapse was defined as a matching positive blood culture after clearance. Predictive models [logistic regression (LR), random forest (RF), support vector machine (SVM) and an ensemble combining the three] were used to predict recurrence-free CVC retention (RFCR) at various time points using a training and test set approach.ResultsOverall, 712 instances CLABSI cleared with ALT were identified. Demographic and microbiological data are summarized in Tables 1 and 2. Few (8%) instances recurred in the first 28 days. 58% recurred at any time within the study period. Rates of RFCR were 75%, 43%, 22% and 10% at 28, 91, 182 and 365 days. Machine learning (ML) models varied in their ability to predict RFCR (Table 3). RF models performed best overall, although no model performed well at 91 days.ConclusionML models provide an opportunity to augment clinical decision making by learning patterns from data. In this case, estimating the likelihood of useful line retention in the future could help guide informed decisions on salvage vs. removal of infected CVCs. Limitations include the heterogeneity of clinical data and the use of an outcome capturing both clinical decision making (line removal) and infection recurrence. With further model development and prospective validation, practical machine learning models may prove useful to clinicians. Disclosures All authors: No reported disclosures.

Demonstrating Efficacy of CHG Bathing Treatment for Inpatient Adult Hematopoietic Stem Cell Transplant Recipients Improves Daily Compliance Among Staff

Topic Significance & Study Purpose/Background/Rationale Daily chlorhexidine gluconate (CHG) bathing is recommended as a method to decrease blood stream infections (BSI) in intensive care units; this strategy may also be effective in hematopoietic stem cell transplant (HSCT) units. Methods, Intervention, & Analysis CHG bathing treatment was initiated in the Adult HSCT unit as standard clinical care in January 2017. Patients admitted for HSCT and recovery from January 2016 through August 2018 were reviewed. Patients transferred from outside hospitals or units were excluded. Patients were grouped by frequency of documented CHG bathing treatment: (1) no CHG (includes patients before CHG implementation and patients with no CHG even after implementation); (2) 75% of admission days. CHG treatment frequency was evaluated until discharge, transfer off unit, or BSI, whichever came first. BSI was defined as either ≥2 positive blood cultures or a single positive blood culture within 24 hours of meeting ≥1 SIRS criteria. A chi square test for trend was performed to evaluate the association between CHG frequency and BSI. Findings & Interpretation One hundred eighty-six inpatients met inclusion criteria (n=79 pre-CHG implementation, 107 post-CHG). BSI developed in 28% of patients with no CHG treatment, 20% with 75% CHG treatment (Table 1). Increased CHG treatment frequency was significantly associated with decreased BSI (p = 0.0028). Discussion & Implications In this retrospective study, CHG bathing treatment was associated with significantly reduced BSI in adult HSCT inpatients. After preliminary data were shared among staff, compliance with daily CHG treatment (>75% of admission days) has increased 7.2-fold in 2018 compared to 2017. Efforts are ongoing to increase compliance by collaborating with hospital informatics to facilitate CHG treatment reminders and improve accuracy of documentation through incorporating CHG bathing orders into the electronic medical record.

Recurrent pituitary abscess: case report and review of the literature

SummaryA 26-year-old woman presented with severe postpartum headaches. Magnetic resonance imaging (MRI) revealed a symmetric, heterogeneous enlargement of the pituitary gland. Three months later, she developed central diabetes insipidus. A diagnosis of postpartum hypophysitis was suspected and corticosteroids were prescribed. Six months later, the pituitary mass showed further enlargement and characteristics of a necrotic abscess with a peripheral shell and infiltration of the hypothalamus. Transsphenoidal surgery was performed, disclosing a pus-filled cavity which was drained. No bacterial growth was observed, except a single positive blood culture for Staphylococcus aureus, considered at that time as a potential contaminant. A short antibiotic course was, however, administered together with hormonal substitution for panhypopituitarism. Four months after her discharge, severe headaches recurred. Pituitary MRI was suggestive of a persistent inflammatory mass of the sellar region. She underwent a new transsphenoidal resection of a residual abscess. At that time, the sellar aspiration fluid was positive for Staphylococcus aureus and she was treated with antibiotics for 6 weeks, after which she had complete resolution of her infection. The possibility of a pituitary abscess, although rare, should be kept in mind during evaluation for a necrotic inflammatory pituitary mass with severe headaches and hormonal deficiencies.Learning points:The possibility of a pituitary abscess, although rare, should be kept in mind during evaluation for a necrotic inflammatory pituitary mass with severe headaches and hormonal deficiencies.In a significant proportion of cases no pathogenic organism can be isolated.A close follow-up is necessary given the risk of recurrence and the high rate of postoperative pituitary deficiencies.

Should we treat patients with only one set of positive blood cultures for extensively drug-resistant Acinetobacter baumannii the same as multiple sets?

Acinetobacter species are not considered skin commensals and under-treatment is an overriding concern when caring for critically-ill patients who are mostly at risk of extensively drug-resistant Acinetobacter baumannii (XDRAB) infections. Hence even a single blood culture yielding XDRAB will tend to prompt intervention. However, field observations suggest that patients with single-positive blood cultures had milder disease and were more likely to be recruited in interventional studies than those with multiple-positive blood cultures, yet no distinction is made in current clinical or trial recruitment practices. To our knowledge, this is the first study to compare the clinical characteristics and outcomes of patients with single-positive versus multiple-positive blood cultures for XDRAB. In this multicenter prospective cohort study of XDRAB bacteremic patients from July 2010 to June 2015, only patients with at least two simultaneously drawn blood cultures were included. The patients were classified as having single-positive or multiple-positive blood cultures according to the number of positive blood cultures yielding XDRAB. The primary end-point was the 28-day mortality. Of a total of 155 patients enrolled, 69 had a single-positive and 86 had multiple-positive blood cultures. Leukopenia (37.2% vs. 16.2%; P = 0.004), thrombocytopenia (56.0% vs. 26.5%; P < 0.001), higher Pitt bacteremia scores (6.6 vs. 5.5, P = 0.03) and higher 28-day mortality rates (70.9% vs. 43.5%; P = 0.001) distinguished patients with multiple-positive from those with single-positive cultures. Multivariate logistic regression showed that multi-positivity independently predicted 28-day mortality (adjusted odds ratio, 2.34; 95% confidence interval (CI), 1.03–5.28; P = 0.04) and the Cox regression confirmed that multi-positivity (adjusted hazard ratio, 1.80; 95% CI, 1.13–2.85; P = 0.01) predicted rapid mortality. Patients with multiple versus single positive blood cultures yielding XDRAB had greater morbidity and mortality. Investigators and clinicians should be aware that the blood culture positivity rate impacts outcomes of XDRAB bacteremia.

135 Sources of streptococcal bacteraemia and their implications for the diagnosis of infective endocarditis

IntroductionThe diagnosis of infective endocarditis (IE) is dependent on the detection of a sustained bacteraemia with multiple positive blood cultures being major criteria in the Duke nosology for IE. The...

A Prospective, Holistic, Multicenter Approach to Tracking and Understanding Bloodstream Infections in Pediatric Hematology-Oncology Patients

OBJECTIVE To assess the burden of bloodstream infections (BSIs) among pediatric hematology-oncology (PHO) inpatients, to propose a comprehensive, all-BSI tracking approach, and to discuss how such an approach helps better inform within-center and across-center differences in CLABSI rate DESIGN Prospective cohort study SETTING US multicenter, quality-improvement, BSI prevention network PARTICIPANTS PHO centers across the United States who agreed to follow a standardized central-line-maintenance care bundle and track all BSI events and central-line days every month. METHODS Infections were categorized as CLABSI (stratified by mucosal barrier injury-related, laboratory-confirmed BSI [MBI-LCBI] versus non-MBI-LCBI) and secondary BSI, using National Healthcare Safety Network (NHSN) definitions. Single positive blood cultures (SPBCs) with NHSN defined common commensals were also tracked. RESULTS Between 2013 and 2015, 34 PHO centers reported 1,110 BSIs. Among them, 708 (63.8%) were CLABSIs, 170 (15.3%) were secondary BSIs, and 232 (20.9%) were SPBCs. Most SPBCs (75%) occurred in patients with profound neutropenia; 22% of SPBCs were viridans group streptococci. Among the CLABSIs, 51% were MBI-LCBI. Excluding SPBCs, CLABSI rates were higher (88% vs 77%) and secondary BSI rates were lower (12% vs 23%) after the NHSN updated the definition of secondary BSI (P<.001). Preliminary analyses showed across-center differences in CLABSI versus secondary BSI and between SPBC and CLABSI versus non-CLABSI rates. CONCLUSIONS Tracking all BSIs, not just CLABSIs in PHO patients, is a patient-centered, clinically relevant approach that could help better assess across-center and within-center differences in infection rates, including CLABSI. This approach enables informed decision making by healthcare providers, payors, and the public. Infect Control Hosp Epidemiol 2017;38:690-696.

Determination of clinical significance of coagulase-negative staphylococci in blood cultures

The aim of this study was to investigate the criteria used to distinguish coagulase-negative staphylococci (CoNS) bacteremia from contamination. We evaluated 162 adult patients with CoNS-positive blood cultures (BCs). Of the 162 patients, 35 (21.6%) had at least 2 positive BCs and 127 (78.4%) had a single positive BC. According to the Laboratory-Confirmed Bloodstream Infection (LCBI) criteria, 24 (14.8%) patients with the same species of CoNS had true bacteremia, and 138 (85.2%) patients had contaminants. Despite the detection of the same CoNS species, 9 of the 24 patients had different CoNS genotypes. Using clinical assessments, only 20 patients were diagnosed with true bacteremia, 8 of them had a single positive BC. We concluded that only using the LCBI criteria or clinical evaluations of a patient were not sufficient to distinguish CoNS bacteremia from contamination. Molecular identification should also be performed as a diagnostic laboratory parameter for CoNS bacteremia.

Single Positive Commensal Blood Culture in hospital setting is associated with higher mortality after hematopoietic stem cell transplantation

BackgroundSingle positive staphylococcal blood culture in a hematopoietic stem cell transplantation (HSCT) recipient is generally regarded as contamination. Such a blood culture (BC) does not fill the criteria for Laboratory-Confirmed Bloodstream Infection (LCBI) and could be described as Single Positive Commensal Blood Culture. The aim of this retrospective cohort analysis was to determine the clinical significance of SPCBC in HSCT recipients. Methods206 patients transplanted between 2007 and 2013 were followed until January 2015. ResultsThe 100-day survival for patients without positive BC was 99.6% compared with 83.9% for LCBI and 82.8% for SPCBC (p=0.0036). The 5-year overall survival (5yOS) was 67.1% for patients without positive BC, 44.9% for LCBI, 34.0% for SPCBC (p<0.0001). The per-day risk of developing SPCBC was identical in autologous and allogenic transplantation. SPCBC remained a significant factor for reduced 5yOS after HSCT in the univariate analysis (HR 2.52, 1.26–5.02, p=0.0001) as well as in the multivariate analysis (HR 2.21, 1.26–3.87, p=0.006). SPCBC consisted solely of different Staphylococcus species with dominance of Staphylococcus epidermidis (64% of SPCBC). ConclusionTo our knowledge this is the first report that specifically shows that short- and long-term survival after HSCT is significantly lower in patients who experience an episode of SPCBC with Staphylococcus spp. during HSCT hospitalization.

Burden of bloodstream infections among ambulatory pediatric hematology/oncology patients with a central line.

262 Background: Pediatric hematology/oncology (PHO) patients are at high risk of bloodstream infections (BSI). The burden of BSI in PHO patients in the ambulatory setting has not been well documented. Methods: The Children’s Hospital Association leads the Childhood Cancer and Blood Disorders Network, a multicenter United States quality improvement collaborative, working to reduce the incidence of inpatient and ambulatory Central Line-Associated BSI (CLABSI) among PHO patients. Positive blood culture events (+BCE) were adjudicated as CLABSI, single positive blood cultures (SPBC) with potential commensals, or secondary BSI (attributed to source other than the central line) following standardized National Healthcare Safety Network definitions. Our study investigated the prevalence of +BCE among all centers with 90% complete monthly reporting of both +BCE and central line days (CLD) for at least one year (n=25) between January 2012 and September 2014. Ambulatory and inpatient BSI rates and 95% confidence intervals (CI) were calculated as the number of +BCE per 1,000 CLD per month. Results: A total of 1,747 +BCE and 4,883,413 CLD were reported among our target ambulatory population, whereas 1,095 +BCE and 353,259 CLD were reported among our corresponding inpatient population [Table]. While the CLABSI and SPBC rates were significantly lower in the ambulatory setting compared to inpatient (p&lt;0.001), the total number of ambulatory CLABSI and SPBC events was 2.0 and 1.6 times higher than inpatient events, respectively. Conclusions: Our findings from a large multicenter collaborative demonstrate the burden of BSI among ambulatory PHO patients and identify benchmarks for future quality improvement work.Further investigation is necessary to develop effective infection reduction strategies for ambulatory PHO patients with central lines. [Table: see text]

Comparison of outcomes between patients with single versus multiple positive blood cultures for Enterococcus: Infection versus illusion?

Enterococci represent one of the most common causative pathogens of bloodstream infections (BSIs). There is debate in the literature regarding the clinical importance of single versus multiple positive blood cultures for Enterococci. This single-center retrospective study found that patients with multiple positive blood cultures experienced increased inpatient mortality and a shorter median survival. Additionally, BSIs >6.7 days resulted in approximately 20% increased mortality. These results are preliminary and require further exploration.