Dual-site blood culture yield and time to positivity in neonatal late-onset sepsis

ObjectiveTo determine whether culture yield and time to positivity (TTP) differ between peripheral and central vascular catheter-derived blood cultures (BCx) in neonatal intensive care unit (NICU) patients evaluated for late-onset sepsis.DesignSingle-centre, retrospective, observational study.SettingLevel IV NICU.ParticipantsThe study included infants >72 hours old admitted to NICU in 2007–2019 with culture-confirmed bacteraemia. All episodes had simultaneous BCx drawn from a peripheral site and a vascular catheter (‘catheter culture’).Main outcome measuresDual-site culture yield and TTP.ResultsAmong 179 episodes of late-onset bacteraemia (among 167 infants) with concurrently drawn peripheral and catheter BCx, the majority (67%, 120 of 179) were positive from both sites, compared with 17% (30 of 179) with positive catheter cultures only and 16% (29 of 179) with positive peripheral cultures only. 66% (19 of 29) of episodes with only positive peripheral BCx grew coagulase-negative Staphylococcus, while 34% (10 of 29) were recognised bacterial pathogens. Among 120 episodes with both peripheral and catheter BCx growth, catheter cultures demonstrated bacterial growth prior to paired peripheral cultures in 78% of episodes (93 of 120, p<0.001). The median TTP was significantly shorter in catheter compared with peripheral cultures (15.0 hours vs 16.8 hours, p<0.001). The median elapsed time between paired catheter and peripheral culture growth was 1.3 hours.ConclusionConcurrently drawn peripheral and catheter BCx had similar yield. While a majority of episodes demonstrated dual-site BCx growth, a small but important minority of episodes grew virulent pathogens from either culture site alone. While dual-site culture practices may be useful, clinicians should balance the gain in sensitivity of bacteraemia detection against additive contamination risk.

Blood culture time to positivity in non-β-hemolytic streptococcal bacteremia as a predictor of infective endocarditis—a retrospective cohort study

Non-β-hemolytic streptococci (NBHS) cause infective endocarditis (IE) and a short blood culture time to positivity (TTP) is associated with risk of IE in bacteremia with other pathogens. In this retrospective population-based cohort study, we investigate if TTP is associated to IE or mortality. Of 263 episodes with NBHS bacteremia, 28 represented IE and the median TTP did not differ significantly between episodes with IE (15 h) and non-IE (15 h) (p=0.51). TTP was similar among those who survived and those who died within 30 days. However, TTP significantly differed when comparing the different streptococcal groups (p<0.001).

Neither Blood Culture Positivity nor Time to Positivity is Associated with Mortality among Patients Presenting with Severe Manifestations of Sepsis: The FABLED Cohort Study

Background Sepsis is a leading cause of morbidity, mortality, and health care costs worldwide. Methods We conducted a multi-center, prospective cohort study evaluating the yield of blood cultures drawn before and after empiric antimicrobial administration among adults presenting to the emergency department with severe manifestations of sepsis (ClinicalTrials.gov: NCT01867905). Enrolled patients who had the requisite blood cultures drawn were followed for 90 days. We explored the independent association between blood culture positivity and its time to positivity in relation to 90-day mortality. Findings 325 participants were enrolled; 90-day mortality among the 315 subjects followed-up was 25·4% (80/315). Mortality was associated with age (mean age in those who died was 72·5 ±15·8 vs. 62·9 ±17·7 years among survivors, p&lt;0·0001), greater Charlson Comorbidity Index (2 (IQR 1,3) vs. 1 (IQR 0,3), p=0·008), dementia (13/80 (16·2%) vs. 18/235 (7·7%), p=0·03), cancer (27/80 (33·8%) vs. 47/235 (20·0%), p=0·015), positive qSOFA score (57/80 (71·2%) vs. 129/235 (54·9%), p=0·009), and normal white blood cell counts (25/80 (31·2%) vs. 42/235 (17·9%), p=0·02). The presence of bacteremia, persistent bacteremia after antimicrobial infusion, and shorter time to blood culture positivity were not associated with mortality. Neither the source of infection nor pathogen affected mortality. Interpretation Although severe sepsis is an inflammatory condition triggered by infection, its 90-day survival is not influenced by blood culture positivity nor its time to positivity. Funding Vancouver Coastal Health; St-Paul’s Hospital Foundation Emergency Department Support Fund; the Fonds de Recherche Santé – Québec (CPY); Intramural Research Program of the NIH, Clinical Center (AL); the Maricopa Medical Foundation

Prognostic Value of the Time-to-Positivity in Blood Cultures from Septic Shock Patients with Bacteremia Receiving Protocol-Driven Resuscitation Bundle Therapy: A Retrospective Cohort Study

Introduction: To evaluate the prognostic value of the time-to-positivity in patients with culture-positive septic shock. Methods: Retrospective study using a prospective data registry was performed at the emergency department of a tertiary hospital. Consecutive adult patients with septic shock (N = 2499) were enrolled between 2014 and 2018. Bacteremia was defined using blood cultures, and viral and fungal pathogens were excluded. The primary outcome was the 28-day mortality. Results: In 803 (46.7%) septic shock patients with bacteremia, median TTP was 10.1 h. The most prevalent isolated bacterial pathogens were Escherichia coli (40.8%) and Klebsiella (23.4%). Although the TTP correlated with a higher sequential organ failure assessment score (Spearman’s rho = −0.12, p < 0.01), it showed no significant difference between the 28-day survivors and non-survivors (10.2 vs. 9.4 days, p = 0.35). In subgroup analysis of the Escherichia coli and Klebsiella bacteremia cases, a shorter TTP showed prognostic value for predicting the 28-day mortality. The optimal TTP cut-off for Escherichia coli and Klebsiella was 10 h and 8 h, respectively. Conclusions: The prognostic value of the TTP in septic shock patients receiving bundle therapy may be limited and its clinical interpretation should only be made on a pathogen-specific basis.

Comparison of microorganism detection and time-to-positivity in pediatric and standard media from three major commercial continuously monitored blood culture systems

New blood culture instrumentation and media formulations have led to improved time-to-positivity (TTP) for positive blood cultures. Data regarding the necessity of pediatric blood culture bottles with contemporary blood culture systems are sparse. We compared performance of three commercial blood culture systems, evaluating impact of blood volumes in standard and pediatric blood culture media across systems. Simulated blood cultures with packed red blood cells and three Gram-positive, four Gram-negative, and one anaerobic organism (final concentrations ranging from 0.5-19 CFU/mL blood) on the VIRTUO, VersaTREK, and Bactec FX were evaluated with FAN Plus, REDOX, and BACTEC Plus media, respectively. For each media/instrument/organism combination 1, 3, 5, and 10 mL blood volumes were evaluated in triplicate. Detection rate was not affected by blood volume. Aerobic organisms that demonstrated variable detection were Kingella kingae, Haemophilus influenzae and Neisseria meningitidis. Bacteroides fragilis was detected in 83%, 100%, and 100% of VIRTUO, VersaTREK, and Bactec anaerobic bottles. Average TTP of standard media for aerobic organisms detected on VIRTUO was decreased compared to VersaTREK (-2.3 h) and Bactec (-4.9 h). Compared to standard media, detection rate and TTP was unchanged on VIRTUO, while TTP was reduced with pediatric media for 2/8 organisms tested on Bactec and 7/8 organisms on VersaTREK, illustrating the potential benefit of pediatric media on VersaTREK or BACTEC when low blood volumes (<5 mL) are collected. These results demonstrate that TTP is decreased on the VIRTUO compared to VersaTREK and Bactec for many microorganisms associated with BSI but may have species-specific limitations.