Search

This work was supported by the Swedish Research Council (grant 521-2011-3442 to R. J. S. and U. S. H. S.), the Innovative Medicines Initiative Joint Undertaking (award 115337, with contribution from the European Union’s Seventh Framework Programme [FP7/2007–2013] and the European Federation of Pharmaceutical Industries and Associations [in-kind contribution]), the European and Developing Countries Clinical Trials Partnership (awards IP.2007.32011.011, IP.2007.32011.012, and IP.2007.32011.013), the Netherlands-African Partnership for Capacity Development and Clinical Interventions Against Poverty-Related Diseases, and the Bill and Melinda Gates Foundation. Background The currently recommended rifampicin dose (10 mg/kg) for treating tuberculosis is suboptimal. The PanACEA HIGHRIF1 trial evaluated the pharmacokinetics and early bactericidal activity of rifampicin doses of up to 40 mg/kg. Conventional statistical analyses revealed no significant exposure-response relationship. Our objectives were to explore the exposure-response relationship for high-dose rifampicin by using pharmacokinetic-pharmacodynamic modeling and to predict the early bactericidal activity of 50 mg/kg rifampicin. Methods Data included time to Mycobacterium tuberculosis positivity of liquid cultures of sputum specimens from 83 patients with tuberculosis who were treated with 10 mg/kg rifampicin (n = 8; reference arm) or 20, 25, 30, 35, or 40 mg/kg rifampicin (n = 15/arm) for 7 days. We used a semimechanistic time-to-event approach to model the time-to-positivity data. Rifampicin exposure and baseline time to culture positivity were explored as covariates. Results The baseline time to culture positivity was a significant covariate on the predicted initial bacterial load, and rifampicin exposure was a significant covariate on the bacterial kill rate in sputum resulting in increased early bactericidal activity. The 90% prediction interval for the predicted median day 7 increase in time to positivity for 50 mg/kg rifampicin was 7.25–10.3 days. Conclusions A significant exposure-response relationship was found between rifampicin exposure and early bactericidal activity. Clinical trial simulations showed greater early bactericidal activity for 50 mg/kg rifampicin. Postprint

Rapid detection of carbapenemase-producing Enterobacteriaceae (CPE) represents a major challenge for microbiology laboratories. We evaluated the BYG Carba v2.0 using a simplified protocol, which detects CPE in less than 30 minutes. This new procedure reduces the hands-on-time from 5 to one minute and only requires a limited amount of material (one to three colonies) thereby preventing the need for subculturing bacterial isolates to reach a larger amount of pure biomass. This multicentre study involved four European reference laboratories. For the 1181 isolates tested across four centres, BYG Carba v2.0 yielded overall sensitivity and specificity of 96.3% (CI95: 94.5-97.5) and 99.7% (CI95: 98.6-100) respectively. Considering only the 670 consecutive isolates tested prospectively, the BYG Carba v2.0 displayed overall positive and negative predictive values of 99.7% (CI95: 95.4-98.9) and 97.5% (CI95: 94.9-98.8). Regarding time to positivity, 85% of CPE detected were positive within ten minutes. The BYG Carba v2.0 is a new highly simplified, rapid and accurate electrochemical assay discriminating between CPE and non-CPE in less than 30 min. The real-time quantified signal allows objective and traceable interpretation of the results., SCOPUS: ar.j, info:eu-repo/semantics/published

The Carba NP test was developed to detect carbapenemase-producing Enterobacteriaceae, and uses imipenem as the reaction substrate. In Japan, IMP-6 metallo-β-lactamase (MBL) producers, which are usually resistant to meropenem but susceptible to imipenem, and IMP-1 MBL producers, which are usually resistant to both carbapenems are prevalent. We performed the Carba NP test with IMP-6 and IMP-1 MBL producers, and both types were detected by the Carba NP test with high sensitivity. All IMP-1 MBL producers were detected by the Carba NP test, but the minimum inhibitory concentrations (MICs) of imipenem varied from 0.25 to >32μg/mL, and the time to positivity varied from 0 to 30min. Time to positivity was significantly correlated with expression levels of blaIMP-1, but not with MICs of imipenem. These results suggested that the Carba NP test can be used as a screening assay for carbapenemase gene expression levels among producers of the same type of carbapenemase. Using this approach, it is possible to determine whether the carbapenem resistance of each carbapenemase-producing Enterobacteriaceae isolate is primarily due to carbapenemase production, or to another mechanism such as outer membrane impermeability.

Introduction Staphylococci is the most commonly isolated bacteria in blood cultures (BC), and is mostly regarded as contamination. However, the clinical relevance and characteristics of CNS other than Staphylococcus epidermidis (Non-SE-CNS) is still unknown. Methods For the purpose of clarifying the epidemiology and clinical significance of Non-Se-CNS infections, we retrospectively evaluated BC isolates of Non-Se-CNS at our institute from May 2013 to March 2017. Infections were defined as true bacteremia if (1) two or more positive BCs of the same species were present (or detection of the same species in another clinically relevant sample), (2) the patient had clinical symptoms as outlined in the Centers for Disease Control and Prevention's definition of primary blood stream infection8 and the symptoms or markers of inflammation (e.g., fever, symptoms, white cell counts, C-reactive protein, or procalcitonin) were improved after pathogen-directed therapy (e.g. either antibiotic therapy and/or removal of the foreign body in the case of catheter-related blood stream infections suspected) and (3) without any other infection. Results During the period, 279 patients with BC positive for Non Se–CNS were identified. 44 patients were excluded, either due to missing data or multiple pathogens in the same BC. Among the remaining 235 patients, 67 (29%) were categorized as true bacteremia (n = 43) or possible infections (n = 24). Resistance rate to methicillin among Non-SE-CNS is about 60%, which is lower than those among S. epidermidis of 78%. Conclusion About 30% of Non-Se-CNS isolates were clinically relevant in our study. Antibiotic susceptibility of Non-SE-CNS is quite different than those of S. epidermidis.

Anaerobes are an important but uncommon cause of bloodstream infections (BSIs). For pediatric patients, routine inclusion of an anaerobic blood culture alongside the aerobic remains controversial. We implemented automatic anaerobic blood culture alongside aerobic blood cultures in a pediatric emergency department (ED) and sought to determine changes in recovery of obligate and facultative anaerobes. This was a cohort study in a pediatric ED (August 2015 to July 2018) that began in February 2017. Blood culture positivity results for true pathogens and contaminants were assessed, along with a secondary outcome of time to positivity (TTP) of blood culture. A total of 14,180 blood cultures (5,202 preimplementation and 8,978 postimplementation) were collected, with 8.8% (456) and 7.1% (635) positive cultures in the pre- and postimplementation phases, respectively. Of 635 positive cultures in the postimplementation phase, aerobic blood cultures recovered 7.6% (349/4,615), whereas anaerobic blood cultures recovered 6.6% (286/4,363). In 211/421 (50.0%) paired blood cultures, an organism was recovered in both cultures. The number of cases where organisms were only recovered from an aerobic or an anaerobic bottle in the paired cultures were 126 (30.0%) and 84 (20.0%), respectively. The TTP was comparable regardless of bottle type. Recovery of true pathogens from blood cultures was approximately 7 h faster than recovery of contaminants. Although inclusion of anaerobic blood cultures only recovered 2 (0.69%) obligate anaerobes, it did allow for recovery of clinically significant pathogens that were negative in aerobic blood cultures and supports the routine collection of both bottles in pediatric patients with a concern of bloodstream infections.

Time to positivity (TTP) and differential time to positivity (DTTP) between central and peripheral blood cultures are commonly used for bacteraemia to evaluate the likelihood of central venous catheter (CVC)-related bloodstream infection. Few studies have addressed these approaches to yeast fungaemia.This study aimed to evaluate TTP and DTTP to assess CVC-related yeast fungaemia (CVC-RYF).We retrospectively analysed the results from 105 adult patients with incident fungaemia, with CVC removed and cultured, collected from 2010 to 2017. The bottles were incubated in a BioMérieux BacT/ALERT 3D and kept for at least 5 days.Of the 105 patients included, most were oncology patients (85.7%) and had of long-term CVC (79.6%); 32 (30.5%) had a culture-positive CVC (defined as CVC-RYF) with the same species as in blood culture, and 69.5% had culture-negative CVC (defined as non-CVC-RYF, NCVC-RYF). Candida albicans represented 46% of the episodes. The median TTP was statistically different between CVC-RYF and NCVC-RYF (16.8 hours interquartile range (IQR) [9.7-28.6] vs 29.4 hours [IQR 20.7-41.3]; P = .001). A TTP10 hours had the best positive likelihood ratio (21.5) for CVC-RYF, although the sensitivity was only 28%. DTTP was available for 52 patients. A DTTP5 hours had a sensitivity of 100% and a specificity of 71% for CVC-RYF.Since the median TTP was 17 hours and the most performing DTTP5 hours, these delays are too long to take a decision in the same operational day. More rapid methods for detecting infected catheters should be tested to avoid unnecessary CVC withdrawal.

The present study aimed to investigate the relationship between the time to positivity (TTP) of blood cultures and the performance of short-term subculture for MALDI-TOF MS-based identification of microorganisms from positive blood cultures in pediatric patients. The study was conducted between April 2018 and July 2019 at a tertiary children's hospital in Eastern China and the TTP of all the blood cultures included was retrospectively collected at the same time. In total, 332 monomicrobial blood cultures were included in the study. Blood cultures that were identified at the genus level (score ≥ 1.700) by the short-term subculture protocol had shorter TTP (median TTP: 17.5 h) than of those not identified (median TTP: 24.6 h; P

Background Pseudomonas aeruginosa (P. aeruginosa) is a major Gram-negative pathogen, which has been reported to result in high mortality. We aim to investigate the prognostic value and optimum cut-off point of time-to-positivity (TTP) of blood culture in children with P. aeruginosa bacteremia. Methods From August 2014 to November 2018, we enrolled the inpatients with P. aeruginosa bacteremia in a 1500-bed tertiary teaching hospital in Chongqing, China retrospectively. Receiver operating characteristic (ROC) analysis was used to determine the optimum cut-off point of TTP, and logistic regression were employed to explore the risk factors for in-hospital mortality and septic shock. Results Totally, 52 children with P. aeruginosa bacteremia were enrolled. The standard cut-off point of TTP was18 h. Early TTP (≤18 h) group patients had remarkably higher in-hospital mortality (42.9% vs 9.7%, P = 0.014), higher incidence of septic shock (52.4% vs12.9%, P = 0.06), higher Pitt bacteremia scores [3.00 (1.00–5.00) vs 1.00 (1.00–4.00), P = 0.046] and more intensive care unit admission (61.9% vs 22.6%, P = 0.008) when compared with late TTP (> 18 h) groups. Multivariate analysis indicated TTP ≤18 h, Pitt bacteremia scores ≥4 were the independent risk factors for in-hospital mortality (OR 5.88, 95%CI 1.21–21.96, P = 0.035; OR 4.95, 95%CI 1.26–27.50, P = 0.024; respectively). The independent risk factors for septic shock were as follows: TTP ≤18 h, Pitt bacteremia scores ≥4 and hypoalbuminemia (OR 6.30, 95%CI 1.18–33.77, P = 0.032; OR 8.15, 95%CI 1.15–42.43, P = 0.014; OR 6.46, 95% CI 1.19–33.19 P = 0.031; respectively). Conclusions Early TTP (≤18 hours) appeared to be associated with worse outcomes for P. aeruginosa bacteremia children.

The molecular bacterial load (MBL) assay is a new tuberculosis biomarker which provides results in ∼4 hours. The relationship between MBL and time-to-positivity (TTP) has not been thoroughly studied and predictive models do not exist. We aimed to develop a model for MBL and identify the MBL-TTP relationship in patients. The model was developed on data from 105 tuberculosis patients from Malawi, Mozambique and Tanzania with joint MBL and TTP observations quantified from patient sputum collected for 12 weeks. MBL was quantified using polymerase chain reaction (PCR) of mycobacterial RNA and TTP using the Mycobacterial Growth Indicator Tube (MGIT) 960 system. Treatment consisted of isoniazid, pyrazinamide and ethambutol in standard doses together with rifampicin 10 or 35 mg/kg. The developed MBL-TTP model included several linked sub-models; a component describing decline of bacterial load in sputum, another component describing growth in liquid culture and a hazard model translating bacterial growth into a TTP signal. Additional components for contaminated and negative TTP samples were included. Visual predictive checks performed using the developed model gave good description of the observed data. The model predicted greater total sample loss for TTP than MBL due to contamination and negative samples. The model detected an increase in bacterial killing for 35 versus 10 mg/kg rifampicin (p=0.002). In conclusion, a combined model for MBL and TTP was developed that described the MBL-TTP relationship. The full MBL-TTP model or each sub-model used separately. Secondly, the model can be used to predict biomarker response for MBL given TTP data or vice versa in historical or future trials. Postprint

Biomarkers for TB treatment response and outcome are needed. This study characterize changes in immune profiles during TB treatment, define biosignatures associated with treatment outcomes, and explore the feasibility of predictive models for relapse. Seventy-two markers were measured by multiplex cytokine array in serum samples from 78 cured, 12 relapsed and 15 failed treatment patients from South Africa before and during therapy for pulmonary TB. Promising biosignatures were evaluated in a second cohort from Uganda/Brazil consisting of 17 relapse and 23 cured patients. Thirty markers changed significantly with different response patterns during TB treatment in cured patients. The serum biosignature distinguished cured from relapse patients and a combination of two clinical (time to positivity in liquid culture and BMI) and four immunological parameters (TNF-β, sIL-6R, IL-12p40 and IP-10) at diagnosis predicted relapse with a 75% sensitivity (95%CI 0.38-1) and 85% specificity (95%CI 0.75-0.93). This biosignature was validated in an independent Uganda/Brazil cohort correctly classifying relapse patients with 83% (95%CI 0.58-1) sensitivity and 61% (95%CI 0.39-0.83) specificity. A characteristic biosignature with value as predictor of TB relapse was identified. The repeatability and robustness of these biomarkers require further validation in well-characterized cohorts.

Detection of coagulase-negative Staphylococcus in blood culture may be a result of either bacteremia or contamination. This often leads to diagnostic uncertainly. Our objective was to develop a method for differentiating whether a coagulase-negative Staphylococcus sp. positive blood culture represents bacteremia or contamination based on positive bottle detection pattern and time to positivity (TTP).This study included 155 and 51 adults with positive blood cultures for Staphylococcus epidermidis and Staphylococcus hominis, respectively, over a three-year period from 2016 to 2018. Positive blood culture cases were categorized as either bacteremia or contamination based on the clinically available information, and the detection pattern and TTP in each category were investigated.A total of 57, 92, and 6 S. epidermidis positive blood cultures were categorized as bacteremia, contamination, and undetermined, respectively, whereas 15 and 36 S. hominis positive blood cultures were categorized as bacteremia and contamination, respectively. For positive blood cultures categorized as bacteremia, all four bottles in two sets of blood cultures were positive in 47/47 S. epidermidis and 14/14 S. hominis, respectively, whereas either one bottle in each of two sets or three bottles in two sets were positive in 10/19 S. epidermidis and 1/4 S. hominis, respectively; most of those TTPs were48 h. Among them, the TTP in catheter-related blood stream infection was24 h.Although clinical assessment is crucial to differentiate between bacteremia and contamination, a combination of positive bottle detection pattern and TTP is a valuable diagnostic auxiliary tool.

The rapid diagnosis of bloodstream infection (BSI) often leads to better clinical outcomes. The present study was conducted to compare two rapid protocols (Sepsityper kit and short-term subculture) for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)-based identification of microorganisms from positive blood cultures in pediatric patients.This study was conducted between May 1, 2018, and April 30, 2019, at a tertiary children's hospital in eastern China. Only monomicrobial blood cultures included in this study were used to conduct the Sepsityper kit protocol and short-term subculture protocol at the same time.In total, 115 monomicrobial blood cultures were included in this study. For the Sepsityper kit protocol, 85.2% and 64.3% of microorganisms were correctly identified to the genus (score ≥ 1.700) and species levels (score ≥ 2.000), respectively. For the short-term subculture protocol, 89.6% and 70.4% of microorganisms were correctly identified to the genus and species levels, respectively. At the genus level (P = .321) or the species level (P = .325), there was no significant difference between the Sepsityper kit protocol and the short-term subculture protocol. Moreover, the short-term subculture protocol exhibited similar performance between Gram-positive bacteria (GPB) and Gram-negative bacteria (GNB) (the genus level: 93.7% (GPB) versus 87.9% (GNB), P = .518; the species level: 68.4% (GPB) versus 81.8% (GNB), P = .147). In addition, the Sepsityper kit protocol exhibited similar performance between GPB and GNB at the genus level (86.1% (GPB) versus 84.8% (GNB), P = 1.000). However, the Sepsityper kit protocol exhibited better performance in GNB at the species level (58.2% (GPB) versus 81.8% (GNB), P = .017). The rates of yeast-like fungi were correctly identified to the genus level (0.0%) or the species level (0.0%) for short-term subculture protocol were significantly lower than those of other microorganisms (the genus level: 92.0%, P = .001; the species level: 72.3%, P = .024). However, a similar result of identification was not found using the Sepsityper kit protocol (the genus level: P = .384; the species level: P = .599). In addition, the two rapid protocols both exhibited better performance at the genus level when the time to positivity (TTP) of blood cultures19 h (the Sepsityper kit protocol: 91.8% (TTP 19 h) versus 77.8% (TTP ≥ 19 h), P = .034; the short-term subculture protocol: 95.1% (TTP 19 h) versus 83.3% (TTP ≥ 19 h), P = .040). In addition, the two rapid protocols both exhibited better performance at the species level when the TTP of blood cultures was19 h (the Sepsityper kit protocol: 78.7% (TTP 19 h) versus 48.1% (TTP ≥ 19 h), P = .000; the short-term subculture protocol: 83.6% (TTP 19 h) versus 55.6% (TTP ≥ 19 h), P = .001).The Sepsityper kit protocol and short-term subculture protocol are both reliable and rapid methods for the identification of most microorganisms from positive blood cultures in pediatric patients. The performance of these two rapid protocols is associated with the TTP of blood cultures.

BACKGROUND: Empiric antibiotic therapy for suspected sepsis is a common practice in neonatal intensive care units (NICU). While standard practice is to discontinue antibiotic therapy when blood cultures remain negative after 48 hours, it remains unclear whether this is the true time range to positivity of blood cultures in the neonatal population across all gestational ages. Gaining an empirical understanding of the time required to detect organisms implicated in neonatal sepsis may allow for a reduction of antibiotic exposure in non-septic neonates. OBJECTIVES: The objectives of this study were to determine (1) the time required for neonatal blood cultures for suspected sepsis to become positive; (2) the proportion of cultures that become positive 24 hours or greater after collection; (3) differences between time to positivity for early versus late onset sepsis and; (4) perinatal and neonatal factors related to time to positivity of blood culture. DESIGN/METHODS: This was a retrospective observational study of blood cultures drawn in neonates within the first 30 days of life with initiation of empiric antibiotic therapy between January 1, 2013 to December 31, 2017 at a level III Canadian NICU. Blood cultures drawn after initiation of antibiotic therapy were excluded. Data was analyzed using descriptive statistics, chi-square and student t-tests to examine differences between characteristics of early versus late onset sepsis, and multivariable logistic regression analyses to examine the relationship between select perinatal and neonatal variables on time to blood culture positivity. This research was approved by the institutional Research Ethics Board. RESULTS: A total of 2213 blood cultures were drawn during the study period. 125 positive blood cultures (5.6%) were identified, out of which 20 were deemed as likely contaminant and hence excluded from the analysis. The median time to positivity of blood cultures was 15 hours (Interquartile range 10–22.3 hours). 22% of positive cultures and 1% of all cultures drawn became positive after 24 hours. Only 8% of the positive cultures were positive after 48 hours. Time to positivity of blood cultures did not differ significantly between suspected early onset sepsis versus late onset sepsis (p=0.75). In the logistic regression analysis that included gestational age, clinical chorioamnionitis, timing of sepsis onset, isolated organism, pre-treatment platelet count, and C-reactive protein, only gestational age was significantly inversely associated with time to positivity (Î(2)=-1.31; p=0.01). CONCLUSION: Results suggest that with the 48-hour empiric antibiotic rule, a large number of neonates potentially receive unnecessary doses of antibiotics as only 1% of all blood cultures become positive after 24 h. A shorter duration of empiric antibiotic therapy may be considered to reduce unnecessary antibiotic exposure in neonates and development of antibiotic resistance in the NICU.

Background and aims: Blood culture (BC) remains gold standard for the evaluation and diagnosis of neonatal sepsis. Time when BC becomes positive and the type of microorganism isolated are crucial i...

Introduction Central line-associated bloodstream infections (CLABSIs) adversely affect patients' hospitalization. Aim We compared semiquantitative roll plate (SQRP) and differential time to positivity (DTP) culture methods in diagnosing CLABSIs. Methodology A retrospective study was conducted in an intensive care unit (ICU) from January 2013 to August 2014. All ICU patients with suspected CLABSIs were included. Blood cultures were taken, while central venous catheter (CVC) tips were cultured using the roll-tip method. DTP was considered positive if CVC lumen blood cultures became positive at least 2 h prior to concurrently drawn peripheral blood cultures with an identical micro-organism. SQRP method was considered positive when ≥15 c.f.u. of a micro-organism identical to that of blood cultures grew. Measures of diagnostic accuracy were calculated. Results SQRP displayed high sensitivity (94.7 %), while DTP showed high specificity (82.5 %). SQRP combined with DTP displayed 100 % sensitivity and negative predictive value. Conclusion SQRP and DTP methods should be evaluated in combination.

Summary Background & aims A retrospective evaluation was undertaken in intestinal failure (IF) patients with long term CVCs to evaluate differential time to positivity (DTP) against paired quantitative blood cultures (PP) for the diagnosis of CRBSI. Methods A list of patients with a diagnosis of CRBSI was obtained from the intestinal failure unit database for a five year period, 2013 to 2017. Microbiology records were reviewed to obtain further information about blood culture and pour plate examinations. Organisms and times of collection, loading and positivity were recorded. Patients with a contemporaneous set of central and peripheral PP and blood cultures were included in an analysis of the sensitivity of DTP compared to PP. Results There were 61 (45.5%) episodes in 56 patients where complete sets of central and peripheral blood cultures and PP were received. All 61 episodes had positive central blood cultures, 59 (96.7%) had positive central line PP and 17 (27.9%) had positive peripheral PP. Using PP as the gold standard, DTP sensitivity was 96.0% for 50 episodes where PP were consistent with CRBSI. Sensitivity increased to 100% for 17 episodes where there were no delays in either collection or loading of blood cultures. Conclusions This is the first evaluation to support the use of DTP as a sensitive test in diagnosing CRBSI in patients with IF and provides confidence to IF centers where pour plate cultures are not available.

Objective To assess the performance of differential time to positivity (DTP) for the diagnosis of catheter-related bloodstream infections (CRBSI). Methods From all episodes of bloodstream infections (BSI) diagnosed during a 15-year period (2003–17) those in which a paired set of blood cultures drawn from a catheter and a peripheral vein were positive for the same microorganism and had a clinically and/or microbiologically defined source were selected. To assess diagnostic discrimination ability and accuracy of DTP for CRBSI, area under the receiver operating characteristic curves (AUC) and performance characteristics of a DTP ≥2 h were computed. Results A total of 512 BSI were included, of which 302 (59%) were CRBSI. Discrimination ability of DTP was low for Staphylococcus aureus (AUC 0.656 ± 0.06), coagulase-negative staphylococci (AUC 0.618 ± 0.081), enterococci (AUC 0.554 ± 0.117) and non-AmpC-producing Enterobacteriaceae (AUC 0.653 ± 0.053); moderate for Pseudomonas aeruginosa (AUC 0.841 ± 0.073), and high for AmpC-producing Enterobacteriaceae (AUC 0.944 ± 0.039). For the entire sample, DTP had a low-to-moderate discrimination ability (AUC 0.698 ± 0.024). A DTP ≥2 h has a low sensitivity for coagulase-negative staphylococci (60%) and very low for S. aureus (34%), enterococci (40%) and non-AmpC-producing Enterobacteriaceae (42%). A DTP cut-off of 1 h improved sensitivity (90%) for AmpC-producing Enterobacteriaceae. Conclusions Differential time to positivity performs well for diagnosing CRBSI only when AmpC-producing Enterobacteriaceae and P. aeruginosa are involved. Performance is low for common Gram-positive organisms and non-AmpC-producing enteric bacilli; a negative test should not be used to rule out CRBSI due to these microorganisms. A DTP ≥1 h may improve accuracy for AmpC-producing Enterobacteriaceae, particularly Enterobacter spp.

Sepsis is a serious clinical problem and estimated to be responsible for 18 million annual deaths worldwide. Therefore, the use and the rapid processing of blood cultures are important for the transition from empiric therapy to directed therapy. The aim of this study was to assess the best blood culture practices in Turkey. We have examined the collection practices and techniques at four different hospitals, and a total of 165.443 blood culture bottles were evaluated (2013-2015). At the preanalytical phase most of the data which were important and which could support hospital quality systems/practices were not entered into the HIS and EpiCenter system. At the analytical phase loading of the bottles and removal of positive bottles primarily occurred between 6:00 and 9:00 AM but the positivity rate of the bottles showed a homogeneous distribution throughout the day. In other words, there were significant delays at processing positive blood culture bottles related to laboratory workers. The effect of education regarding best practices, transition from single bottle to two bottle cultures was successful in all hospitals. Single bottle usage decreased below 10% in all hospitals. Significantly more positive cultures were detected at multiple cultures when compared with the single bottle collection practice. In retrospective patient records, it was seen that all the laboratories reported the results of Gram staining to the clinics. However, these data were not recorded to the Epicenter. The contamination rates of Ankara Numune Hospital and Akdeniz University Faculty of Medicine Hospital are 6.2% and 5.4% respectively, contamination rates were not reported in other hospitals. The most common isolates detected in blood cultures were Escherichia coli, Klebsiella pneumoniae, Enterococcus faecium, Staphylococcus aureus, and Acinetobacter baumannii. The mean time for the detection of these organisms were less than 20 hours in the aerobic bottle and anaerobic bottles. A total of 79.6% of facultative anaerobic isolates were detected in both bottles; 9.8% were detected only in the aerobic bottles; 10.6% of the isolates were detected only in the anaerobic bottles. As a result, the educational efforts in Turkey have met with success for transition from collecting single bottle blood culture sets to two bottle blood cultures. However, further efforts are needed to increase the number of blood culture sets collected during a 24 hour's period. In addition, errors at the preanalytical, analytical and postanalytical periods (taking samples, loading bottles into the system and processing positive blood cultures) should be eliminated. C1 [Basustaoglu, Ahmet] Baskent Univ, Dept Med Microbiol, Fac Med, TR-06790 Ankara, Turkey. [Suzuk Yildiz, Serap] MoH Gen Directorate Publ Hlth, Dept Microbiol Reference Lab & Biol Prod, Ankara, Turkey. [Mumcuoglu, Ipek; Kursun, Senol] Ankara Numune Training & Res Hosp, Lab Med Microbiol, Ankara, Turkey. [Karahan, Zeynep Ceren; Evren, Ebru] Ankara Univ, Dept Med Microbiol, Fac Med, Ankara, Turkey. [Ogunc, Dilara; Ozhak Baysal, Betil] Akdeniz Univ, Dept Med Microbiol, Fac Med, Antalya, Turkey. [Kaleli, Ilknur; Demir, Melek] Pamukkale Univ, Dept Microbiol, Fac Med, Denizli, Turkey. [Murray, Patrick] BD Diagnost Syst, Hunt Valley, MD USA.

International audience; Currently, no guideline provides recommendations on the duration of empirical antimicrobial treatment (EAT) in prosthetic joint infection (PJI). The aim of our study was to describe the time to growth of bacteria involved in PJI, rendering possible decreased duration of EAT. Based on a French multicentre prospective cohort study, culture data from patients with confirmed hip or knee PJI were analysed. For each patient, five samples were processed. Time to positivity was defined as the first positive medium in at least one sample for virulent pathogens and as the first positive medium in at least two samples for commensals. Definitive diagnosis of polymicrobial infections was considered the day the last bacteria were identified. Among the 183 PJIs, including 28 polymicrobial infections, microbiological diagnosis was carried out between Day 1 (D1) and D5 for 96.7% of cases. There was no difference in the average time to positivity between acute and chronic PJI (p = 0.8871). Microbiological diagnosis was given earlier for monomicrobial than for polymicrobial infections (p = 0.0034). When an optimized culture of peroperative samples was carried out, almost all cases of PJI were diagnosed within five days, including polymicrobial infections. EAT can be re-evaluated at D5 according to microbiological documentation.

Sepsis is a serious clinical problem and estimated to be responsible for 18 million annual deaths worldwide. Therefore, the use and the rapid processing of blood cultures are important for the transition from empiric therapy to directed therapy. The aim of this study was to assess the best blood culture practices in Turkey. We have examined the collection practices and techniques at four different hospitals, and a total of 165.443 blood culture bottles were evaluated (2013-2015). At the preanalytical phase most of the data which were important and which could support hospital quality systems/practices were not entered into the HIS and EpiCenter system. At the analytical phase loading of the bottles and removal of positive bottles primarily occurred between 6:00 and 9:00 AM but the positivity rate of the bottles showed a homogeneous distribution throughout the day. In other words, there were significant delays at processing positive blood culture bottles related to laboratory workers. The effect of education regarding best practices, transition from single bottle to two bottle cultures was successful in all hospitals. Single bottle usage decreased below 10% in all hospitals. Significantly more positive cultures were detected at multiple cultures when compared with the single bottle collection practice. In retrospective patient records, it was seen that all the laboratories reported the results of Gram staining to the clinics. However, these data were not recorded to the EpiCenter. The contamination rates of Ankara Numune Hospital and Akdeniz University Faculty of Medicine Hospital are 6.2% and 5.4% respectively, contamination rates were not reported in other hospitals. The most common isolates detected in blood cultures were Escherichia coli, Klebsiella pneumoniae, Enterococcus faecium, Staphylococcus aureus, and Acinetobacter baumannii. The mean time for the detection of these organisms were less than 20 hours in the aerobic bottle and anaerobic bottles. A total of 79.6% of facultative anaerobic isolates were detected in both bottles; 9.8% were detected only in the aerobic bottles; 10.6% of the isolates were detected only in the anaerobic bottles. As a result, the educational efforts in Turkey have met with success for transition from collecting single bottle blood culture sets to two bottle blood cultures. However, further efforts are needed to increase the number of blood culture sets collected during a 24 hours' period. In addition, errors at the preanalytical, analytical and postanalytical periods (taking samples, loading bottles into the system and processing positive blood cultures) should be eliminated. © 2019 Ankara Microbiology Society. All rights reserved.

Little progress has been made in decreasing the incidence rate of salmonellosis in the US over the past decade. Mitigating the contribution of contaminated raw meat to the salmonellosis incidence rate requires rapid methods for quantifying Salmonella, so that highly contaminated products can be removed before entering the food chain. Here we evaluated the use of Time-to-Positivity (TTP) as a rapid, semi-quantitative approach for estimating Salmonella contamination levels in ground beef. Growth rates of 14 Salmonella strains (inoculated at log 1 to −2 CFU/g) were characterized in lean ground beef mTSB enrichments and time-to-detection was determined using culture and molecular detection methods. Enrichments were sampled at five timepoints and results were used to construct a prediction model of estimated contamination level by TTP (superscript indicates time in hours) defined as TTP4: ≥ 5 CFU/g; TTP6: ≤ 5, ≥ 1 CFU/g; TTP8: ≤ 1, ≥ 0.01 CFU/g; with samples negative at 8 h estimated ≤ 0.01 CFU/g. Model performance measures showed high sensitivity (100%) and specificity (83% and 93% for two detection methods) for samples with a TTP4, with false negative rates of 0%.

The authors regrets that there is a typo error on the Abbreviation section of their published paper. "Area under the curve" should have been abbreviated to "AUC" instead of "A". The authors have requested that this be noted. The original article has been corrected.

Background Staphylococcus aureus (S. aureus) is a common cause of bacteremia, which leads to significant morbidity and mortality. We investigated the relationship between time to positivity (TTP) and clinical outcomes in children with S.aureus bacteremia in the China. Methods A retrospective study of Staphylococcus aureus bacteremia inpatient was performed in Children’s Hospital of Chongqing Medical University in China between 29 January 2014 and 29 August 2017. TTP and clinical parameters were determined and analyzed. The receiver operating characteristic (ROC) curves were plotted for optimal cut-off selection, multivariate logistic regression tests were performed to evaluate the association between TTP and clinical outcomes. Results Overall, 84 cases were enrolled. We stated that in-hospital mortality is significantly higher in the early TTP (≤17 h) than in the late TTP (> 17 h) group (57.14% vs 7.14%, P = 0.000). Septic shock occurred in 57.14% of patients with early TTP and in 18.57% of patients with late TTP (P = 0.002). Detailed multivariate and statistical analysis revealed that early TTP, need for vasoactive agent were independent risk factors of in-hospital mortality; early TTP, need for vasoactive agent and APACHE II score ≥ 15 were independent risk factors of septic shock incidence in S. aureus bacteremia children. Conclusions Overall, TTP of ≤17 h appeared to correlate with the worse outcomes for S. aureus bacteremia children. These results have important implications in the assessments and management of pediatric S. aureus bacteremia in a clinical setting. Trial registration Retrospectively registered.

Early phase 2 tuberculosis (TB) trials are conducted to characterize the early bactericidal activity (EBA) of anti-TB drugs. The EBA of anti-TB drugs has conventionally been calculated as the rate of decline in colony forming unit (CFU) count during the first 14 days of treatment. The measurement of CFU count, however, is expensive and prone to contamination. Alternatively to CFU count, time to positivity (TTP), which is a potential biomarker for long-term efficacy of anti-TB drugs, can be used to characterize EBA. The current Bayesian nonlinear mixed-effects (NLME) regression model for TTP data, however, lacks robustness to gross outliers that often are present in the data. The conventional way of handling such outliers involves their identification by visual inspection and subsequent exclusion from the analysis. However, this process can be questioned because of its subjective nature. For this reason, we fitted robust versions of the Bayesian nonlinear mixed-effects regression model to a wide range of TTP datasets. The performance of the explored models was assessed through model comparison statistics and a simulation study. We conclude that fitting a robust model to TTP data obviates the need for explicit identification and subsequent "deletion" of outliers but ensures that gross outliers exert no undue influence on model fits. We recommend that the current practice of fitting conventional normal theory models be abandoned in favor of fitting robust models to TTP data.

OBJECTIVES Blood cultures (BCs) are essential in the evaluation of neutropenic fever. Modern BC systems have significantly reduced the time-to-positivity (TTP) of BC. This study explores the probability of bacteraemia when BCs have remained negative for different periods of time. METHODS All adult patients with neutropenia and bacteraemia were included (January 2012-February 2016). Predictive clinical factors for short (≤16 hours) and long (>24 hours) TTP were determined. The residual probability of bacteraemia was estimated for the scenario of negative BC 24 hours after collection. RESULTS The cohort consisted of 154 patients, accounting for 190 episodes of bacteraemia. Median age of 61 years, 60.5% were male. In 123 (64.7%) episodes, BC yielded a single Gram-positive micro-organism and in 49 (25.8%) a Gram-negative micro-organism (median TTP 16.7, 14.5 hours respectively, P

The objective of this study was to show the differences between paired blood cultures (PBC) versus single blood cultures (SBC) in the microbiologic yield, the sensitivity to detect pathogens and the time to positivity (TTP). We performed a retrospective study examining 112,570 blood culture samples over a 5-year period from July 2011 to May 2016 in the BacT/ALERT® 3D automated blood culture system (bioMerieux, Marcy l'Etoile, France). Bacteria and yeasts were identified using the VITEK® 2 Compact system (bioMerieux, Marcy l'Etoile, France). True-positives and contaminated bottles were defined and analysed separately. We analysed TTP and adherence to blood volume guidelines for a convenience sample of 510 and 999 sequential positive cultures, respectively. Out of 49,438 PBC samples, 5810 (11.7%) were positive. In 63,132 SBC samples, 4552 (7.2%) were positive (p

Background: Blood cultures are essential for the diagnosis and further appropriate treatment in children with suspected sepsis. In most hospitals, children will be empirically treated or closely monitored for at least 48 h awaiting results of blood cultures. Several studies have challenged the optimal duration of empiric treatment in the era of continuously monitored blood culture systems. The aim of our study was to investigate time-to-positivity (TTP) of blood cultures in children with proven sepsis. Methods: The Swiss Pediatric Sepsis Study prospectively enrolled children 0-16 years of age with blood culture positive sepsis between September 2011 and October 2015. TTP was prospectively assessed in six participating academic pediatric hospitals by fully automated blood culture systems. Results: In 521 (93%) of 562 bacteremia episodes (493 children, median age 103 days, range 0 days-16.9 years) a valid TTP was available. Median TTP was 12 h (IQR 8-17 h, range 0-109 h). By 24, 36, and 48 h, 460 (88%), 498 (96%), and 510 (98%) blood cultures, respectively, were positive. TTP was independent of age, sex, presence of comorbidities, site of infection and severity of infection. Median TTP in all age groups combined was shortest for group B streptococcus (8.7 h) and longest for coagulase-negative staphylococci (16.2 h). Conclusion: Growth of bacteria in blood cultures is detectable within 24 h in 9 of 10 children with blood culture-proven sepsis. Therefore, a strict rule to observe or treat all children with suspected sepsis for at least 48 h is not justified.

PurposeCandidemia is an important issue of nosocomial bloodstream infections, and is associated with a high mortality rate. However, little information is available before final species identification, which takes days after the episode of candidemia. This study tried to determine whether time to positivity (TTP) for yeast helps in predicting the species of candidemia.MethodsA retrospective cohort study was conducted in Taiwan, which included 434 episodes of nonduplicated candidemia during the period between 2006 and 2009. The demographic features, clinical characteristics, TTP for yeast, and acute illness scores were included for analysis.ResultsThe mean age of patients with candidemia was 70.4 ± 15.2 years, and the 30-day crude mortality rate was 48.2%. Forty-five percent of patients suffered from shock status with a mean Acute Physiological and Chronic Health Evaluation II score of 27.0 ± 8.7 and a mean Sequential Organ Failure Assessment score of 9.7 ± 4.5, whereas 50% were admitted to the intensive care units. Candida albicans was still the most commonly identified pathogen (58.1%), followed by C. tropicalis (14.7%), C. parapsilosis (13.1%), and C. glabrata (8.3%). Results of multivariate logistic regression showed that TTP for yeast within 48 hours would more favor C. tropicalis (p = 0.044), and less favor C. glabrata (p = 0.025) and C. parapsilosis (p

Blood culture remains the gold standard for diagnosing neonatal septicemia. Although automated continuous monitor- ing blood culture systems have generally been shown to be superior to conventional manual systems, there are few data relating to their use specifically in neonates. The aim of this study was to compare the manual method of blood culture with an automated BacT/Alert 3D system for detection of neonatal septicemia in terms of rate of recovery of pathogens and time to positivity. One hundred and one matched pairs of blood culture specimens from patients on a neonatal intensive care unit were evaluated by the two methods. The yield of significant pathogens with the BacT/Alert 3D system was 45.5%, compared with 18.8% with the manual method ( P< 0.0001). Moreover, streptococci, which are important neonatal pathogens, were detected exclusively with the automated system. The median time to positivity with the automated system was 11.5 h, compared with 24 h for the manual system. The BacT/Alert 3D system offers more sensitive and rapid detection of neonatal septicemia than a manual blood culture method. The clinical benefits of this may justify the additional cost of automated blood culture systems in developing countries where manual systems currently remain commonplace.

The electronic medical records at 2 children’s hospitals were reviewed from June 1, 2011 to May 31, 2013 for all patients with sickle cell disease who presented with fever. Of a total of 390 blood cultures drawn, 11 cultures (2.8%) turned positive with only 1 (0.3%) growing a true pathogen. This culture turned positive in 13 hours. There were 154 patients who received exclusive outpatient management of fever. Fourteen patients (9.1%) completed 1 acute care visit, 16 patients (10.4%) completed 2 acute care visits, and 124 patients (80.5%) completed 3 acute care visits. Of those treated exclusively as outpatients, there was 1 positive culture that was considered a contaminant. Although the overall rate of positivity was low, this study confirms previous findings that pediatric blood cultures become positive with pathogens within 48 hours. Given the high rate of compliance and early time to positivity of true pathogens, we suggest that follow-up for the febrile sickle cell disease patients can be treated on an outpatient basis.

Objective To evaluate the clinical usefulness and safety of the differential-time-to-positivity (DTP) method for managing the suspicion of catheter-related bloodstream infection (CR-BSI) in comparison with a standard method that includes catheter removal in critically ill patients. Methods-Design A prospective randomized study was carried out. Setting: A 16-bed clinical-surgical ICU (July 2007-February 2009). Interventions: Patients were randomly assigned to one of two groups at the time CR-BSI was suspected. In the standard group, a standard strategy requiring catheter withdrawal was used to confirm or rule out CR-BSI. In the DTP group, DTP without catheter withdrawal was used to confirm or rule out CR-BSI. Measurements: clinical and microbiological data, CR-BSI rates, unnecessary catheter removals, and complications due to new puncture or to delays in catheter removal. Results Twenty-six patients were analyzed in each group. In the standard group, 6 of 37 suspected episodes of CR-BSI were confirmed and 5 colonizations were diagnosed. In the DTP group, 5 of 26 suspected episodes of CR-BSI were confirmed and four colonizations were diagnosed. In the standard group, all catheters (58/58, 100%) were removed at the time CR-BSA was suspected, whereas in the DTP group, only 13 catheters (13/41, 32%) were removed at diagnosis, and 10 due to persistent septic signs (10/41, 24%). In cases of confirmed CR-BSI, there were no differences between the two groups in the evolution of inflammatory parameters during the 48 hours following the suspicion of CR-BSI. Conclusions In critically ill patients with suspected CR-BSI, the DTP method makes it possible to keep the central venous catheter in place safely.

While parenteral nutrition (PN) has revolutionized the management of patients with intestinal failure (IF), central line-associated bloodstream infections (CLABSIs) remain a leading cause of mortality and morbidity in this population. The objective of this study is to characterize the presentation of CLABSIs in pediatric IF and to determine the time to positivity of blood cultures.A retrospective cohort study of children with IF who presented to our institution for evaluation of a possible CLABSI from January 1, 2012, to December 31, 2012, was performed.Sixty patients with IF were identified. There were 33 cases of CLABSI in 16 patients, with a rate of 1.5 infections per 1000 catheter days. There were no significant differences in age, growth parameters, or catheter days between patients with or without CLABSI. Fever was documented in 85% of patients with CLABSI. These patients demonstrated an increased percentage of neutrophils and higher C-reactive protein levels compared with patients without CLABSI. The mean time to culture positivity was 13.2 hours, and 97% of cultures were positive within 24 hours.Our data suggest that most pediatric patients with IF who have CLABSI develop positive cultures within 24 hours, and the absence of fever and leukocytosis does not necessarily indicate the absence of infection. These findings may support clinical practice guidelines in favor of shorter hospital stay when CLABSI is suspected; however, a prospective analysis of CLABSI in this population is recommended to determine the safety and appropriate setting prior to any practice change.