True Bacteremia Research Articles

Clinical outcomes of urinary tract infection caused by extended spectrum beta-lactamase producing Enterobacteriaceae: a retrospective observational study comparing patients with and without systemic inflammatory response syndrome.

AimIn severe urinary tract infection (UTI), susceptible antibiotics should be given. With the recent increase of multidrug‐resistant bacteria, especially extended spectrum beta‐lactamase producing Enterobacteriaceae (ESBL‐E), broad‐spectrum antibiotics, such as carbapenems, are used more frequently, which could lead to a further increase of multidrug‐resistant bacteria. We aimed to analyze the relationship between initial empirical antibiotic appropriateness and clinical outcomes in UTI, especially in patients with systemic inflammatory response syndrome (SIRS) and ESBL‐E.MethodsA retrospective observational study from 2012 to 2017.ResultsAmong urine culture‐positive cases with ≥105 colony‐forming units/mL (n = 1,880), true UTI cases were extracted (n = 844) and divided into the SIRS group (n = 336 [ESBL‐E12.8% (43/336)]) and non‐SIRS group (n = 508 [ESBL‐E12.6% (64/508)]). In the SIRS ESBL‐E group, the initial antibiotics were susceptible in 55.8% (24/43), among which 91.7% (22/24) improved and 8.3% (2/24) deteriorated or died. The initial antibiotics were resistant in 44.2% (19/43), among which 47.4% (9/19) improved with the initial antibiotics, 47.4% (9/19) improved after escalating antibiotics, and 5.3% (1/19) deteriorated or died. In the SIRS group, 14 cases had true bacteremia with ESBL‐E. Seven cases were initiated with inappropriate antibiotics; four cases showed improvement before or without antibiotic change and three cases improved after antibiotic escalation.ConclusionInitiation of narrow‐spectrum antibiotics in septic UTI with ESBL‐E might not deteriorate the clinical outcome if promptly escalated on clinical deterioration or with ESBL‐E culture results. Further investigation is warranted to guide judicious use of initial antibiotics.

161. Evaluating the Predictive Value of Blood Culture Bottle Reporting for Coagulase Negative Staphylococci-Positive Cultures: Assessing Contamination vs. True Bacteremia

BackgroundCoagulase-negative staphylococci (CoNS) are common blood culture (BCx) contaminants, but can also be causes of true blood stream infection (BSI). As a result, the clinical interpretation of CoNS positive BCx poses a significant challenge for providers and drives unnecessary antibiotic use, extended lengths of stay, and increased hospital costs. Despite these challenges, little is known about whether the number of positive BCx bottles within a set can be used to predict contamination vs. true BSI.MethodsThis study was conducted in an 865-bed tertiary care academic medical center in Richmond, VA. A retrospective chart review of CoNS-positive BCx from October to December 2018 was performed. Data collection included patient demographics, number of positive bottles within a set (i.e., were 1 or 2 bottles positive), care setting, antibiotic use, clinical judgement of contamination, and additional workup following the positive BCx result. Polymicrobic BCx were excluded.Results50 patients (mean age 58.2 years, 60% male) with CoNS-positive BCx were included in this study. Forty (80%) of the cultures had only 1 of 2 BCx bottles positive within a set. 10 (20%) were positive from both bottles in the set. All patients were drawn in the Emergency Department and 90% were subsequently admitted to the hospital. Upon chart review, 47 (94%) and 3 (6%) of cultures were considered to be contaminants and real BSI, respectively. Of those judged to be contaminants, 10 (20%) were positive in both bottles within a set, and thus falsely suggested true BSI. Of the 3 judged to be true BSI, 2 (66%) were positive in 1 out of 2 bottles, and thus falsely suggested contamination.42 (84%) patients had repeat BCx drawn following the initial positive culture, and 26 (52%) were continued on IV antibiotics. Forty (80%) of the cultures were judged contaminants by the primary medical service, and 77% stopped antibiotics (20/26) when CoNS was identified.ConclusionThese data show that reporting the number of bottles which are positive within a set provides misleading information and should not be used to determine whether a culture result represents contamination or true BSI.Disclosures All authors: No reported disclosures.

1166. Infection Rate in Venous–Venous Extracorporeal Membrane Oxygenation (VV-ECMO)

BackgroundThe Extracorporeal Life Support Organization (ELSO) Infectious Disease Taskforce has identified infection rates as an area requiring further study. We aimed to evaluate our patients on venous–venous extracorporeal membrane oxygenation (VV ECMO) for infection rates, organisms, and specific factors that may alter infection risk.MethodsRetrospective data were collected from September 2012 to 2015 for adult patients on VV ECMO. Demographic information as well as type and location of cannulation, antibiotics prior to and during cannulation, and presence of bacteremia were obtained. Counts and percentages are reported for categorical variables.Results47 patients between 18 and 82 years of age with a median of age of 58 years were included. 76.6% (N = 36) were male. The average number of hospital days until cannulation was 7.8 days. 400 ECMO days were captured with a range of time on ECMO of 1–41 days. 46.8% (N = 22) of patients were alive at the time of discharge. 70.2% (N = 32) of cannulations were in the OR (Figure 1). 55% (N = 26) of patients had a Right Ventricular Assist Device (RVAD) with in-line oxygenator. 66% (N = 31) of all patients were on antibiotics prior to cannulation for other indications while 53% (N = 25) of all patients received perioperative antibiotics (Figure 2). 59% (N = 28) of all patients had blood cultures while on ECMO, with only 8% (N = 4) of all patients returning positive. Of the positive cultures, 2 were true bacteremia resulting in an infection rate of 5 per 1,000 ECMO days (Figure 3). One patient grew Escherichia coli while the other grew Escherichia coli and Streptococcus pneumoniae. Neither patient received antibiotics perioperatively or for other indications (Figure 4). Due to the low number of infected patients, further statistical analysis could not be performed.ConclusionWe report a low rate of bloodstream infection amongst our VV-ECMO patients. Further investigation to ascertain trends in infection rate with cannulation location/type as well as association with antibiotic is currently being pursued. Other avenues of research will include a comparison of infection rates between VV and Venous Arterial (VA) ECMO. Information from these investigations will help aid the development of guidelines to minimize the rate of nosocomial infections in ECMO patients. Disclosures All authors: No reported disclosures.

242 Incidence of Bacteremia and Antibiotic Use in Adult Patients Hospitalized With Laboratory-Confirmed Respiratory Syncytial Vrus

Obtaining blood cultures (BCs) as part of diagnostic evaluations of patients admitted from the emergency department (ED) with respiratory symptoms is commonplace, but can lead to overuse of antibiotics for treatment of patients with confirmed respiratory viruses. Multiple factors including the “surviving sepsis campaign,” core measures established by Joint Commission and Centers for Medicare and Medicaid Services and EMR ordering prompts all encourage early blood cultures and antibiotic administration. The objectives of this study were to determine the incidence of bacteremia in hospitalized adults with PCR-confirmed RSV, chest x-rays consistent with bacterial pneumonia and antibiotic use within the first 24 hours of presentation to the ED in efforts to assist with the development of a future decision rule. From October 2017 - April 2018, prospective surveillance identified hospitalized adults residing in New York City with ≥ 2 symptoms of acute respiratory infection and PCR-confirmed RSV evaluated in the EDs of two academically affiliated teaching hospitals. BCs were obtained, and antibiotics were started at the discretion of treating physicians. Demographic, clinical, and laboratory data were abstracted from the medical record. The incidence of positive blood cultures and proportion of subjects prescribed antibiotics and chest x-rays consistent with pneumonia, ie, reported infiltrate or opacity, were analyzed. During the study period, 169 adults with RSV were admitted from the ED whose mean age was 67.4 years; 59.8% were ≥ 65 years old and 58.6% were female. Subjects had the following comorbidities: cardiovascular (55.0%), pulmonary (55.0%), or immunocompromising conditions, eg, HIV or cancer (30.8%). In all, 42 (24.9%) had temperature ≥ 38.0 0C, 51 (30.2%) had white blood cell counts <3,500 or >11,000, and 6 (3.6%) had mean arterial pressure <65 mm Hg. All 169 patients had blood cultures obtained and were started on antibiotics by emergency physicians. One-third (60, 35.5%) had chest x-rays with reported infiltrate/opacity.Fourteen (8.3%) patients had a positive blood culture; 8 (4.7%) had pathogenic bacteria detected (3 Streptococcus pneumonia, 1 Group A streptococci, 1 Staphylococcus aureus, and 3 gram negative species) and 6 (3.6%) had probable contaminants, eg, Capnocytophaga spp. or Proprionbacterium acnes. Of the 8 with pathogenic bacteria, 4 had chest x-rays consistent with pneumonia. True bacteremia was uncommon in adults with documented RSV. Despite the documented viral etiology of their respiratory symptoms, all had blood cultures obtained and antibiotics started. The use of viral PCR testing paired with identifying high risk groups for bacteremia could better guide emergency physicians' therapeutic approach

Strategies for increasing diagnostic yield of community-onset bacteraemia within the emergency department: A retrospective study.

Bloodstream infections (BSI) are associated with high mortality. Therefore, reliable methods of detection are of paramount importance. Efficient strategies to improve diagnostic yield of bacteraemia within the emergency department (ED) are needed. We conducted a retrospective analysis of all ED encounters in a high-volume, city-centre university hospital within Germany during a five-year study period from October 2013 to September 2018. A time-series analysis was conducted for all ED encounters in which blood cultures (BCs) were collected. BC detection rates and diagnostic yield of community-onset bacteraemia were compared during the study period (which included 45 months prior to the start of a new diagnostic Antibiotic Stewardship (ABS) bundle and 15 months following its implementation). BCs were obtained from 5,191 out of 66,879 ED admissions (7.8%). Bacteraemia was detected in 1,013 encounters (19.5% of encounters where BCs were obtained). The overall yield of true bacteraemia (defined as yielding clinically relevant pathogens) was 14.4%. The new ABS-related diagnostic protocol resulted in an increased number of hospitalised patients with BCs collected in the ED (18% compared to 12.3%) and a significant increase in patients with two or more BC sets taken (59% compared to 25.4%), which resulted in an improved detection rate of true bacteraemia (2.5% versus 1.8% of hospital admissions) without any decrease in diagnostic yield. This simultaneous increase in BC rates without degradation of yield was a valuable finding that indicated success of this strategy. Thus, implementation of the new diagnostic ABS bundle within the ED, which included the presence of a skilled infectious disease (ID) team focused on obtaining BCs, appeared to be a valuable tool for the accurate and timely detection of community-onset bacteraemia.

From contamination to infective endocarditis\u2014a population-based retrospective study of Corynebacterium isolated from blood cultures

Corynebacterium is a genus that can contaminate blood cultures and also cause severe infections like infective endocarditis (IE). Our purpose was to investigate microbiological and clinical features associated with contamination and true infection. A retrospective population-based study of Corynebacterium bacteremia 2012–2017 in southern Sweden was performed. Corynebacterium isolates were species determined using a matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Patient were, from the medical records, classified as having true infection or contamination caused by Corynebacterium through a scheme considering both bacteriological and clinical features and the groups were compared. Three hundred thirty-nine episodes of bacteremia with Corynebacterium were identified in 335 patients of which 30 (8.8%) episodes were classified as true infection. Thirteen patients with true bacteremia had only one positive blood culture. Infections were typically community acquired and affected mostly older males with comorbidities. The focus of infection was most often unknown, and in-hospital mortality was around 10% in both the groups with true infection and contamination. Corynebacterium jeikeium and Corynebacterium striatum were significantly overrepresented in the group with true infection, whereas Corynebacterium afermentans was significantly more common in the contamination group. Eight episodes of IE were identified, all of which in patients with heart valve prosthesis. Six of the IE cases affected the aortic valve and six of seven patients were male. The species of Corynebacterium in blood cultures can help to determine if a finding represent true infection or contamination. The finding of a single blood culture with Corynebacterium does not exclude true infection such as IE.

Ability of procalcitonin to differentiate true bacteraemia from contaminated blood cultures in an emergency department

ObjectivesTo analyse and compare the ability of procalcitonin (PCT), C-reactive protein (CRP) and leukocytes to differentiate true bacteraemia from contaminated blood cultures in patients seen in the emergency department (ED) for an episode of infectious disease. MethodsObservational, retrospective and descriptive analytical study of all blood cultures with positive growth extracted in an ED in adult patients (≥18 years) during 2016 and 2017. The follow-up was carried out over a 30-day period to calculate the predictive power and the prognostic performance for true bacteraemia. ResultsA total of 266 blood cultures with positive growth were included in the study. Out of these, 154 (57.9%) were considered true bacteraemia and 112 (42.1%) were considered to be contaminated blood cultures. The area under the Receiver Operating Characteristic curve (AUC-ROC) for PCT to predict true bacteraemia was 0.983 (95% CI: 0.972–0.994; p<0.001) and, considering a cut-off value of ≥0.43ng/ml, PCT achieved 94% sensitivity, 91% specificity, positive predictive value of 94%, and negative predictive value of 92%. The AUC-ROC obtained for CRP was 0.639 (95% CI: 0.572–0.707, p<0.001), for leukocytes of 0.693 (95% CI: 0.630–0.756, p<0.001) and for immature leukocytes (>10% bands) of 0.614 (95% CI: 0.547–0.682, p<0.001). The mean values for PCT were 3.44 (SD 6.30)ng/ml in true bacteraemia vs 0.16 (SD 0.18)ng/ml in contaminated blood cultures (p<0.001). ConclusionsIn blood cultures with positive growth extracted in an ED, PCT achieves the best prognostic performance of true bacteraemia vs contaminated blood cultures, better than CRP and leukocytes.

The species distribution, antimicrobial resistance and risk factors for poor outcome of coagulase-negative staphylococci bacteraemia in China

ObjectiveCoagulase-negative staphylococci (CoNS) are one of the major opportunistic pathogens and the incidence of CoNS bacteraemia is increasing. However, most of the CoNS-positive blood cultures are contaminants rather than true CoNS bacteraemia. In order to minimize contamination, we defined true CoNS bacteraemia as the patient that has two or more identical CoNS-positive blood cultures drawn within 48 h in this study and the objective of this study was to analyse the species distribution and antibiotic resistance and to identify risk factors for 30-day mortality of the true CoNS-bacteraemia.MethodBy reviewing the electronic medical database, this study retrospectively analysed patients diagnosed as CoNS bacteraemia by blood cultures in a comprehensive tertiary care hospital in China from January 1, 2014, to December 31, 2017.ResultA total of 1241 patients with 1562 episodes of CoNS-positive blood cultures were recorded in the database but only 157 patients were finally diagnosed as true CoNS bacteraemia after contaminants were excluded. All these 157 patients (12.7%, 157/1241) had bacteraemia-related clinical symptoms. Among the 157 patients, the most common species were Staphylococcus hominis (40.8%), Staphylococcus epidermidis (36.3%) and Staphylococcus capitis (11.5%). The antimicrobial susceptibility tests showed that all CoNS had a high rate of resistance to penicillin (94.9%), oxacillin (93.6%) and erythromycin (92.4%). Resistance to gentamicin (22.3%) and rifampicin (10.8%) was low, and none of the bacteria were resistant to vancomycin or linezolid. The 30-day mortality of patients with CoNS bacteraemia was up to 12.7% (20/157), and the multivariate logistics regression analysis showed that chronic renal failure (OR 5.9, 95% CI 1.6–21.5, p = 0.007) and chronic liver failure (OR 4.0, 95% CI 1.2–13.1, p = 0.024) were both the significant independent risk factors for the 30-day mortality of CoNS bacteraemia.ConclusionStaphylococcus hominis and Staphylococcus epidermidis were the most common species in CoNS bacteraemia. All CoNS had high multi-drug resistance, but gentamicin and rifampicin had a relatively lower resistance and could be considered as alternative antibiotics for anti-CoNS bacteraemia in addition to vancomycin and linezolid. Additionally, patients with chronic renal failure or chronic liver failure have a higher 30-day mortality after the onset of CoNS bacteraemia.

Capacidad de la procalcitonina para diferenciar bacteriemia verdadera de los hemocultivos contaminados en el servicio de urgencias

ObjectivesTo analyse and compare the ability of procalcitonin (PCT), C-reactive protein (CRP) and leukocytes to differentiate true bacteraemia from contaminated blood cultures in patients seen in the emergency department (ED) for an episode of infectious disease. MethodsObservational, retrospective and descriptive analytical study of all blood cultures with positive growth extracted in an ED in adult patients (≥18 years) during 2016 and 2017. The follow-up was carried out over a 30-day period to calculate the predictive power and the prognostic performance for true bacteraemia. ResultsA total of 266 blood cultures with positive growth were included in the study. Out of these, 154 (57.9%) were considered true bacteraemia and 112 (42.1%) were considered to be contaminated blood cultures. The area under the Receiver Operating Characteristic curve (AUC-ROC) for PCT to predict true bacteraemia was 0.983 (95% CI: 0.972-0.994; P<0.001) and, considering a cut-off value of≥0.43 ng/ml, PCT achieved 94% sensitivity, 91% specificity, positive predictive value of 94%, and negative predictive value of 92%. The AUC-ROC obtained for CRP was 0.639 (95% CI: 0.572-0.707, P<.001), for leukocytes of 0.693 (95% CI: 0.630-0.756, P<.001) and for immature leukocytes (>10% bands) of 0.614 (95% CI: 0.547-0.682, P<.001). The mean values for PCT were 3.44 (SD 6.30) ng/ml in true bacteraemia vs. 0.16 (SD 0.18) ng/ml in contaminated blood cultures (P<.001). ConclusionsIn blood cultures with positive growth extracted in an ED, PCT achieves the best prognostic performance of true bacteraemia vs. contaminated blood cultures, better than CRP and leukocytes.

Performance enhancement of procalcitonin by high-sensitivity C-reactive protein at the optimal cutoff in predicting bacteremia in emergency department adult patients

Pathogenic bacteremia portends a high mortality risk in adult patients admitted to an Emergency Department (ED). This study aims to investigate the effect of adding high-sensitivity C-reactive protein (hs-CRP) to procalcitonin (PCT) and lactate in predicting bacteremia, Gram-negative (GNB) and Gram-positive bacteremia (GPB), using the optimal cutoff derived from the receiver operating characteristics analysis. We evaluated the diagnostic measures, including the positive-test likelihood (LR+), the negative-test likelihood (LR−), and the diagnostic odds ratio (DOR) using a single-center retrospective analysis design. This Standards for Reporting Diagnostic-compliant study comprised 886 consecutive adults who were admitted to the ED in 2010; to this cohort, a 22.2% prevalence of true bacteremia was subsequently confirmed. At the cutoff of 3.9 μg/L, PCT had a DOR of 5.3 (95% confidence interval [CI]: 3.76–7.61) and LR + of 2.8 (95% CI: 2.3–3.4) in predicting overall bacteremia. Elevated PCT and lactate (cutoff at 2 mmol/L), increased the DOR and LR + to 6.3 (95% CI: 4.27–9.29) and 4.0 (95% CI: 3.1–5.2). The DOR and LR + were further improved to 7.1 (95% CI: 4.2–11.95) and 5.6 (95% CI: 3.7–8.6), respectively, when hs-CRP at the cutoff of 1238 nmol/L was added to PCT plus lactate. High-sensitivity CRP at the cutoff of 1,255 nmol/L can enhance the discriminative power raising DOR and LR + values for GPB. The elevation of hs-CRP at the optimal cutoff might improve the diagnostic performance to predict unspecified bacteremia and GPB, but not GNB.

Prevalence and Antibiotic Resistance Profile of Coagulase Negative Staphylococci causing True Bacteraemia in a Tertiary care Hospital

Prevalence and Antibiotic Resistance Profile of Coagulase Negative Staphylococci causing True Bacteraemia in a Tertiary care Hospital

1801. Impact of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) on Clinical Outcomes in Patients with Gram Positive Blood Cultures in a Diverse, Multicenter Healthcare System With a Central Laboratory

BackgroundRapid diagnostic testing in combination with real-time antimicrobial stewardship intervention can reduce time to de-escalation of empiric antibiotics and discontinuation of unnecessary therapy. This study aims to evaluate the clinical impact of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) for Gram-positive organism identification for blood cultures across a healthcare system comprised of pediatric, adult academic, and adult community hospitals utilizing a central microbiology laboratory with unique antimicrobial stewardship resources at each site.MethodsThis multicenter retrospective study compared patients with a positive blood culture for a Gram-positive organism identified via MALDI-TOF MS to a historical cohort identified using conventional methods. Primary outcome was time to optimal therapy (TTOT). Secondary outcomes included time to effective therapy, duration of therapy, time to microbiologic clearance, hospital length of stay (LOS), ICU LOS, recurrence, readmission, in-hospital mortality, and all-cause mortality.ResultsThis study included 129 cultures (12% pediatric patients) in the conventional period and 129 cultures (19% pediatric patients) in the MALDI-TOF MS group. Of the total 258 blood cultures included, 147 (57%) represented true bloodstream infection and 111 (43%) were deemed to be contaminants. Despite a median reduction in time to organism identification (60.0 vs. 45.4 hours, P < 0.001), there was no difference in the primary outcome of overall median TTOT between the two groups (70.7 hours vs. 65.9 hours, P = 0.407). There were no significant differences for any secondary outcomes. Overall TTOT was longer as distance from the central laboratory increased (47.3 hours at central site vs. 76.9 hours at distance >30 miles). Among contaminants, median TTOT was reduced from 72.5 hours with conventional methods to 59.8 hours with MALDI-TOF MS (P = 0.015). Conclusion. Implementation of MALDI-TOF MS for organism identification may not reduce time to optimal therapy in patients with true Gram-positive bacteremia. However, it can result in a significant reduction in time to discontinuation of unnecessary therapy for patients with contaminated cultures. Figure 1. Differences in outcomes for conventional methods vs. MALDI-TOF MS Disclosures All authors: No reported disclosures.

157. Reducing Blood Culture Contamination Rates Through the Use of a Red Top Tube Discard

BackgroundSepticemia is a major cause of death in the United States and accounts for up to $16.7 billion in annual health care expenses. Blood culture is the gold standard for laboratory diagnosis of bacteremia and resultant septicemia; however, false-positive blood cultures hinder the accurate determination of true bacteremia with often serious implications. The goal of this study was to determine the efficacy of collecting a 1 mL discard in a red tube prior to blood culture collection and to assess its effectiveness in reducing contamination rates in Hartford Hospital Emergency Department (HHED).MethodsDuring the months of June to December 2017 blood cultures were collected by the phlebotomy team using ChloraPrep (chlorhexidine) as the sole disinfecting agent. Blood cultures consisted of BD BACTEC plus Aerobic/F and BD BACTEC Lytic/10 Anaerobic drawn at the same time and monitored on BD BACTEC FX instrument for 5 days. Prior to collecting blood cultures 1 mL of blood was collected in a red top tube and discarded. Monthly and overall contamination rates were then compared with 2016 in which a red top discard tube was not used.ResultsDuring June to December 2016, there were a total of 9,576 blood cultures collected with a total of 178 contaminants and an overall contamination rate of 1.9%. During June to December 2017, there were a total of 9,133 blood cultures collected with a total of 73 contaminants and an overall contamination rate of 0.8%. During both years, our contamination rates were well below the CLSI recommendation; however, a significant reduction in blood culture contamination was observed after the use of a Red Top discard tube (0.8% vs. 1.9%) (Figures 1–3). ConclusionThe cost of a standard blood draw with Red Top tubes is minimal (few cents) while a single collection using an initial specimen diversion device (ISDD) can range from $15 to $18. During the course of this study, the use of a standard Red Top discard cost approximately $456 (2017); if an ISDD was used instead, this would have generated $136,995 in healthcare cost. At our institution, we were able to keep our contamination rates below 1% after the implementation of a standard Red Top discard tube. This suggests that the use of a Red Top discard prior to blood culture collection is an effective means for reducing and maintaining a low blood contamination rate.Disclosures All authors: No reported disclosures.

Clinical significance of coagulase-negative Staphylococci isolated from blood cultures

Objective To analyze clinical characteristics of bloodstream infections caused by coagulase-negative Staphylococci (CNS) and antibiotic resistance of the bacteria, so that to provide basis for the clinical diagnosis and treatment. Methods A retrospective analysis of CNS in blood cultures collected from 108 hospitalized patients in Puai Hospital of Tongji Medical College from January 2016 to December 2017 was performed. The antimicrobial susceptibilities were tested by Kirby-Bauer method and E test method. For measurement variables, normally distributed variables were compared using t test, and non-normal distributed data were compared using Mann-Whitney U test. Categorical variables were compared using χ2 test. Results Of the 108 patients, 66 were male and 42 were female; the age range was 26 to 98 years and the average was 49 years. According to the criteria for bacteremia, 36 of 108 (33.3%) patients with CNS-positive blood cultures were diagnosed with bacteremia and 72 (66.7%) cases were contaminated. CNS bacteremia mainly occurred in the intensive care unit and nephropathy ward. Among them, 23 (62.2%) patients were catheter-related blood stream infections, and 11 (29.7%) patients were dialysis catheter-related bloodstream infections. Fifteen of 36 (41.7%) strains were isolated within 48 hours of admission. The level of serum procalcitonin (PCT) for bacteremia patients was 2.56 (1.44, 7.60) μg/L, and that was 0.13 (0.05, 0.23) μg/L in contaminated patients. The difference was statistically significant (Z=8.097, P 0.05). After antibiotic treatment, 26 of 36 bacteremia patients were survived. The PCT levels before antibiotic treatment were 2.05 (1.42, 4.32) μg/L, and 0.24 (0.07, 0.61) μg/L after antibiotic treatment. Serum PCT was decreased significantly after antibiotic treatment (Z=4.457, P 0.05). No significant difference was found in white blood cell count between survivors and deaths at 28 days (t=0.771, P>0.05). There was no statistical difference of the anti-bacterial drug susceptibility between pathogens and contaminants (P>0.05). All strains were sensitive to vancomycin, teicoplanin and linezolid. Conclusions The incidence of CNS contamination in blood culture is relatively high. It is important to distinguish true bacteraemia from contamination by a review of the clinical and laboratory indicators. PCT is of clinical value to indicate CNS infection and to monitor therapeutic effect. Key words: Bacteremia; Coagulase negative Staphylococci; Procalcitonin

You can’t b. cereus: an unusual presentation of bacillus cereus

We present a case of a 74-year- old male with a complicated medical history who was admitted to theWe present a case of a 74-year-old male with a complicated medical history who was admitted to the medical floor for evaluation and management of failure to thrive and malnutrition. On hospital day 9 he became febrile and blood cultures were found to be positive for B. cereus and Enterobacter cloacae, which were persistent. He had an extensive negative workup for the cause of his bacteremia, however, we present a number of possibilities from his presentation and a literature review. Our case was consistent with other cases in the literature as our patient could be considered immunocompromised secondary to malnutrition and type II diabetes. B. cereus in blood cultures is often considered a contaminant but can be true bacteremia and should be worked up if multiple blood cultures are positive or if there is a clinical suspicion. Â

True Versus False Bacteremia in Infants and Children Less Than 3 Years of Age.

The objective of this study was to examine patient history as well as clinical and laboratory features associated with true bacteremia versus false bacteremia in previously healthy febrile children ages 0 to 36 months in the era of polyvalent conjugate pneumococcal immunization. Using retrospective chart review, we examined history, physical examination, and laboratory characteristics associated with true and false bacteremia. We included subjects under 3 years old, with a positive blood culture obtained in the emergency department or clinic from July 2011 to July 2013, and fever defined as a temperature of greater than or equal to 100.4°F by history or examination. We excluded those with a previously known underlying disease process that could increase the risk for positive blood culture, for example, immunodeficiency, cancer, cystic fibrosis, or significant skin disorders such as severe eczema, as well as patients with any indwelling central line, shunt, or other implanted device, or recent hospitalization for a febrile illness. Thirty subjects (24%) had true bacteremia, and 97 (76%) had false bacteremia. In the multivariable logistic regression analysis, exposure to sick contacts (odds ratio, 0.1; 95% confidence interval, 0.01-0.6; P = 0.01) and increased hours to positive blood culture (odds ratio, 0.8; 95% confidence interval, 0.8-0.9; P < 0.001) remained significant factors associated with false bacteremia. Age, maximum reported temperature, and reported days of fever were not associated with true bacteremia. We found that previously healthy children with true bacteremia are more likely to grow bacteria faster on blood culture and lack exposure to sick contacts than children with false bacteremia.

Coagulase-negative staphylococcal bacteraemia in cancer patients. Time to positive culture can distinguish bacteraemia from contamination

Background: Coagulase-negative staphylococci (CoNS) are the most common contaminants of blood cultures, however, we sometimes have difficulties in determining their clinical significance. It is still controversial that there is a significant difference between the contamination group and the true bacteraemia group in the time to positivity (TTP) of blood cultures. We validated the relationship between a TTP and the presence of CoNS bacteraemia in cancer patients by using an objective, non-judgmental definition for CoNS contamination.Methods: We retrospectively reviewed 175 sets of blood cultures drawn from 95 patients that yielded CoNS from October 2011 to March 2013. We considered as contamination if an isolate of CoNS was identified in one out of multiple sets of blood cultures. We investigated the TTP, the threshold values and corresponding likelihood ratios to distinguish CoNS bacteraemia from contamination.Results: The median TTP in CoNS bacteraemia group was significantly shorter than that in contamination group (14 h 45 min and 20 h 31 min, respectively, p = .0157). A TTP of ≤16 h had a specificity of 83% for predicting CoNS bacteraemia, and that of >20 h had a sensitivity of 86% for predicting CoNS contamination.Conclusions: We validated that the median TTP in CoNS bacteraemia group was significantly shorter than that in their contamination group, and that a TTP of ≤16 h was associated with CoNS bacteraemia, while that of >20 h was associated with CoNS contamination, if evaluated with an objective, non-judgmental definition for CoNS contamination.

Significance of blood cultures in nursing home-acquired pneumonia.

The significance of blood cultures in nursing home-acquired pneumonia (NHAP) is incompletely understood. We retrospectively analyzed the clinical and laboratory features of 515 patients with NHAP admitted to our hospital over an 11-year period. Blood cultures were obtained from 336 patients (65.2%). We compared 13 and 323 patients with positive and negative blood cultures, respectively. The former showed lower systolic blood pressure and higher blood urea nitrogen (BUN), creatinine, C-reactive protein (CRP), and A-DROP scores than the latter. With regard to A-DROP parameters, patients with positive blood cultures showed significantly higher rates of dehydration (BUN≥21mg/dL) and low blood pressure (systolic blood pressure≤90mmHg). Multivariate analysis identified CRP values and low blood pressure as independent predictors of bacteremia: CRP (odds ratio [OR] 1.11; 95% confidence interval [CI] 1.04-1.19, P=0.003) and low blood pressure (OR 6.03; 95% CI 1.06-34.25, P=0.04). A receiver operating characteristic curve indicated that CRP was of moderate accuracy (area under the curve=0.75), and its diagnostic accuracy was optimal at a cut-off point of 19.2mg/dL (sensitivity 69%, specificity 87%). Since the probability of true bacteremia is very low in NHAP, obtaining blood cultures from all patients with NHAP is unnecessary. However, our results suggest blood cultures are warranted from patients with high CRP values (≥20mg/dL) or low blood pressure.

True Pathogen or Contamination: Validation of Blood Cultures for the Diagnosis of Nosocomial Infections in a Developing Country.

Blood culture results are frequently used to guide antibiotic decision-making, but culture contaminants need to be distinguished from true pathogens. To assess the contamination rate of blood cultures and validate a method to distinguish between true bacteraemia and contamination. We analysed blood culture results from children who were admitted to the paediatric ICU and paediatric wards at the Sardjito Hospital, Yogyakarta, Indonesia between December 2010 and February 2013. For each positive culture result, the type of isolated organism, time to positivity, and the number of positive culture sites were considered to classify the isolate as representing a true bacteraemia or contaminant. There were 1293 cultures obtained from blood and 308 (23.8%) were positive for bacterial growth. Fifty-three (4.1%) of the total cultures drawn fulfilled criteria for contaminants. The most common blood culture contaminants were coagulase-negative staphylococci. Using standardized criteria, it is possible to implement a working method to identify true nosocomial infection from blood culture contaminant, and thus limit the effect of contaminated blood culture on irrational antibiotic use.

Late-onset Neonatal Sepsis-A 10-year Review From North Queensland, Australia.

Late-onset sepsis (LOS) in neonates contributes significantly to both morbidity and mortality. To determine the incidence of LOS, risk factors for disease and the impact on subsequent hospital course, we evaluated a cohort of 6340 neonates admitted to the neonatal intensive care unit and of neonates (3-28 days) admitted from the community between January 2005 and January 2016. This was a retrospective case review of all neonates admitted with suspected LOS who had positive blood culture and/or cerebrospinal fluid cultures, for an organism determined to be a pathogen. Of 6340 neonates who survived beyond 3 days, 2271 (35.8%) had 1 or more blood cultures collected for suspected LOS. Of these, 146 (6.4%) positive blood cultures were thought to represent true bacteremia. The vast majority of infections (73%) were caused by Gram-positive organisms, with coagulase-negative staphylococci accounting for 39.8% of infections. Late-onset neonatal sepsis occurred predominantly in the 24-28-week age group (75.9%) and in neonates who weighed less than 1000 g (73.6%). The incubation time for positive blood cultures for Gram-negative sepsis was less (13 hours) when compared with Gram-positive sepsis (20 hours). Thrombocytopenia, elevated C-reactive protein and chorioamnionitis were consistently associated with late-onset Gram-negative sepsis (P < 0.05). Eight neonates (6%) died secondary to LOS. LOS contributes significantly to mortality and morbidity in neonates and remains a challenge to clinicians. Necessary steps to reduce late-onset neonatal sepsis should be undertaken.