Time to blood culture positivity as a predictor of clinical outcomes and severity in adults with bacteremic pneumococcal pneumonia

Determinants of time to positivity in bloodstream infections: an analysis of a population-based cohort in Queensland, Australia

PURPOSE

Time to Positivity (TTP) measures the interval from incubation to bacterial growth detection in blood cultures. Although shorter TTP is associated with higher mortality, factors associated with TTP remain uncertain.

METHODS

A retrospective cohort study was conducted among Queensland residents with positive blood cultures between 2000-2019. Incident bloodstream infections (BSIs) were identified using Pathology Queensland data, with demographic, clinical, and outcome data linked to state-wide databases.

RESULTS

The study analysed 84,341 patients with monomicrobial BSI with a median patient age of 65.6 years (IQR 45.4-78.1), and most infections being community-associated (77.0%). Age showed a non-linear relationship with TTP, and male sex was linked with slightly higher TTP (Incidence Rate Ratio (IRR) 1.01; 95% Confidence Intervals (CI) 1.00-1.02; p = 0.011), reflecting a small but measurable association. Liver disease and malignancy were associated with lower TTP (IRR 0.93; 95% CI 0.91-0.95; p < 0.0001 and IRR 0.95; 95% CI 0.94-0.97; p < 0.0001 respectively), whilst diabetes showed no significant difference (IRR 1.01; 95% CI 1.00-1.02; p = 0.0840). Hospital onset infections exhibited longer TTPs (IRR 1.09; 95% CI 1.08-1.10; p < 0.0001).

CONCLUSIONS

There are several host characteristics associated with TTP that may in part explain the complex relationship between this variable and mortality. Beyond microbiological factors such as isolate type, TTP is also influenced by clinical variables including patient demographics and infection characteristics highlighting its potential as a prognostic marker. Further evaluation is needed to clarify its role in predicting patient outcomes and guiding tailored treatment strategies.

Isolation of Multiple Positive Cultures at Resection Arthroplasty is a Predictor of Failure Following Reimplantation

BACKGROUND

Although it is well established that the type of organism can be a risk factor for failure in patients with periprosthetic joint infection (PJI), no study to date has examined the impact of the number of positive cultures on treatment outcomes in patients undergoing 2-stage exchange. The purpose of this multicenter study was to determine the prognostic utility of multiple positive cultures at resection as a predictor of failure following reimplantation.

METHODS

This retrospective multicenter study identified 437 patients with chronic knee PJI who had undergone 2-stage exchange arthroplasty with a minimum of 1 year of follow-up following reimplantation. PJI was defined with use of the 2013 Musculoskeletal Infection Society (MSIS) criteria. Patients with culture-negative PJI were excluded (n = 138). Treatment failure was defined as either any reoperation for infection or PJI-related mortality. Multivariable regression controlling for risk factors for failure after a 2-stage arthroplasty was performed to determine whether ≥2 positive intraoperative cultures at resection can predict outcomes following reimplantation when compared with a single positive culture.

RESULTS

Two hundred and ninety-nine patients were included. At a mean follow-up of 6.2 ± 2.6 years, 48 patients (16.1%) experienced failure. Patients who had a failure were more likely to have had a longer interstage interval (p = 0.038) and were also more likely to have had ≥2 positive cultures at the time of resection arthroplasty (95.8% versus 75.3%; p = 0.001). On regression analysis, ≥2 positive cultures at resection was the only variable that was identified as a risk factor for failure following reimplantation in both the univariate (odds ratio [OR], 7.55 [95% CI, 2.24 to 47.0]; p = 0.006) and multivariable models (OR, 8.12 [95% CI, 2.31 to 51.9]; p = 0.005).

CONCLUSIONS

This is the first study to examine the impact of the number of positive cultures on outcomes in patients with PJI. We found that the presence of ≥2 positive cultures at resection was an indicator of a poor prognosis and resulted in a greater than eightfold increase in the risk of treatment failure in patients undergoing a 2-stage exchange.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Modified time-to-positivity as a crucial determinant of short-term mortality among adults with community-onset monomicrobial bloodstream infections

The potential performance of time-to-positivity (TTP) in predicting the prognosis of individuals experiencing Bloodstream infections (BSIs) has achieved little consensus. The retrospective cohort of 1015 treatment-naive adults with community-onset monomicrobial BSIs aimed to assess the performance of TTP and modified TTP (mTTP, TTP plus transportation time) in predicting 30-day mortality after adjusting for prognostic confounders, particularly the time-to-appropriate antibiotic (TtAa). Through Spearman's correlation, a significant linear-by-linear association (ρ = -0.943, P = 0.005) was exhibited between mTTP and 30-day mortality rates, but no significant association (ρ = -0.423, P = 0.26) was disclosed between TTP and 30-day mortality rates in the overall patient population. In the logistic regression model, each additional hour of mTTP or TTP was associated with an average decrease of 5 % (adjusted odds ratio [AOR], 0.95; P = 0.001) or 3 % (AOR, 0.97; P = 0.03) in the 30-day mortality rates, respectively, after adjusting for independent predictors of 30-day mortality. In conclusion, for adults with community-onset monomicrobial BSIs, mTTP revealed a favorable performance over TTP alone in predicting short-term mortality.

Blood culture time to positivity in pediatric patients with bloodstream infection in rural Gambia

Objectives

There is a lack of data on the time to blood culture positivity (TTP) in pediatric populations in low-income countries. We aimed to assess the host and pathogen factors associated with TTP in children aged under 5 years in rural Gambia.

Methods

Between September 2019 and December 2023, we collected blood cultures from children under 5 years with suspected bloodstream infections. We determined the TTP from the time of culture incubation to when bacterial growth was first detected.

Results

Overall, 547 invasive bacteria pathogens were evaluated. The median TTP was 19.2 hours and 70%, 76%, 89%, and 96% of cases had TTP at 24, 36, 48, and 72 hours, respectively. Streptococcus pneumoniae had the shortest median TTP (17.4 hours), whereas Neisseria species had the longest (45 hours). TTP was dependent on the pathogen and independent of age, sex, temperature, clinical outcome, nutritional status, and length of hospital stay. Gram-positive bacteria had shorter TTP than gram-negative bacteria (18.6 vs 19.6 hours, P < 0.01).

Conclusions

In rural Gambia, most blood cultures from pediatric patients would turn positive within 48 hours of incubation. A maximum of 48 hours of observation after the commencement of antibiotic therapy in hospitalized children may be sufficient for clinicians to receive feedback on blood culture results.

A mathematical model to estimate the probability of blood cultures positive for pyogenic streptococci

Aims

The aim of this study was to assess the possible use of time to positivity (TTP) of blood cultures (BCs) collected at the Emergency Department (ED) to estimate the probability of pyogenic streptococci versus other Gram positive cocci in pairs and chains, such as Streptococcus pneumoniae, other viridans group streptococci or enterococci.

Methods

All patients 18 years of age or older evaluated at the ED from whom BCs were collected and were positive for Gram positive cocci in pairs and chains at the microscopic examination, were included in the study. The BCs included were collected by venipuncture, were mono-microbial and were the first bottles that flagged positive in each set. Complete blood count requested simultaneously with BCs along with medical history taken by the ED physician were also evaluated.

Results

In our case series, all BCs positive for Gram positive cocci in pairs or chains at microscopic examination with a TTP ≤6.3 hours were consistent with a pyogenic streptococcus (100% specificity; 95% CI: 92.7-100). Consequently, a TTP ≤6.3 hours has a 100% positive predictive value (95% CI: 30.9-100). Conversely, no pyogenic streptococci were recovered from positive BCs with a TTP >12.6 hours. Therefore, as screening test, it has 100% sensitivity (95% CI: 77-100) and 100% negative predictive value (95% CI: 83.4-100). The binomial logistic regression model showed how as TTP increases, in BCs positive for Gram positive cocci in pairs and chains at the microscopic examination, the probability of a positive result for pyogenic streptococci decreases (odds ratio: 0.548; 95% confidence interval: 0.387-0.775; P=0.001).

Conclusions

The results of this study are an adjunctive tool to clinical aspects and fast microbiology laboratory tests to help assessing the likelihood of a positive blood culture for pyogenic streptococci.

Time to positivity as a predictor of catheter-related bacteremia and mortality in adults with Pseudomonas aeruginosa bloodstream infection

BACKGROUND

Time to positivity (TTP) and differential TTP (DTP) emerge as diagnostic and prognostic tools for bloodstream infections (BSI) though specific cut-off values need to be determined for each pathogen. Pseudomonas aeruginosa BSI (PAE-BSI) is of critical concern, particularly in immunocompromised patients, due to high mortality rates. Catheter-related infections are a common cause, necessitating rapid and accurate diagnostic tools for effective management (source-control).

METHODS

Unicentric retrospective observational study analyzing the diagnostic utility and best cut-off values of time to positivity (TTP) and differential time to positivity (DTP) to identify catheter-related PAE-BSI and the association of TTP with 30-day mortality.

RESULTS

1177 PAE-BSI cases TTP were included in the study. TTP was available in all episodes whereas DTP was available in 355 episodes. Breakthrough bacteremia disregarding the TTP, more than one positive blood culture or > 7 days with a catheter in place and both a TTP < 13h and a DTP > 2h were independently associated to catheter-related PAE-BSI. Secondly, lower TTP were significantly associated with higher 30-day mortality rates in both catheter-related and non-catheter-related PAE-BSI. For catheter-related infections, TTP < 14h exacerbated mortality among patients among patients in whom the catheter was not removed within 48h (OR 2.9[1.04-8]); whereas for other sources TTP < 16h increased mortality (OR 1.6[1.1-2.4]) particularly when the empiric antibiotic therapy was not active (OR 3.8[1.5-10]).

CONCLUSION

These findings advocate for the routine use of TTP over DTP as a diagnostic tool to guide timely interventions such as catheter removal, thereby potentially improving patient outcomes in PAE-BSI. Moreover, lower TTP have also prognostic implications in both catheter-related and non-catheter-related infections.

The role of time to positive blood cultures in enhancing the predictive capability of DENOVA score for diagnosing infective endocarditis in patients with Enterococcus faecalis bacteremia

DENOVA-score is useful to stratify the risk of infective endocarditis (IE) in Enterococcus faecalis bacteremia. Recently, time to positive (TTP) of blood cultures has also been related with a higher risk of IE. The objective was to evaluate DENOVA- score with TTP to improve its specificity. We performed a retrospective, case-control study in adult patients with E. faecalis bacteremia. Thirty-nine patients with definite E. faecalis IE and 82 with E. faecalis bacteremia were included. The addition of a TTP ≤ 8 h to DENOVA-score did not improve the diagnostic accuracy of this score.

Diabetes Mellitus and Pneumococcal Pneumonia

Currently, there are more than 500 million people suffering from diabetes around the world. People aged 65 years or older are the most affected by this disease, and it is estimated that approximately 96% of diabetes cases worldwide are type 2 diabetes. People with diabetes mellitus are at an increased risk of infections such as pneumonia, due to a series of factors that may contribute to immune dysfunction, including hyperglycemia, inhibition of neutrophil chemotaxis, impaired cytokine production, phagocytic cell dysfunction, altered T cell-mediated immune responses and the co-existence of chronic comorbidities. Rates of infection, hospitalization and mortality in diabetic patients are reported to be higher than in the general population. Research into the risk of infectious diseases such as pneumonia in these patients is very important because it will help improve their management and treatment.

Subculturing and Gram staining of blood cultures flagged negative by the BACTEC™ FX system: Optimizing the workflow for detection of Cryptococcus neoformans in clinical specimens

Objective

To investigate whether an incubation time of 5 days (Aerobic/F, Anaerobic/F) and 14 days (Myco/F) blood culture bottles is sufficient to prevent false-negative results.

Methods

We evaluated 1,244 blood bottles (344 patients) defined as negative by the BACTEC™ FX system. We also reviewed published cases and our own cases of bloodstream infection caused by Cryptococcus neoformans and simulated different scenarios, including different inoculation concentrations, bottle types, and clinical isolates.

Results

Two bottles (0.16%) were found to contain C. neoformans when subcultured and Gram stained. A 5-day protocol with Aerobic/F bottles was insufficient for the growth of C. neoformans in some cases, and C. neoformans grew better in Myco/F bottles than in Aerobic/F bottles.

Conclusion

Subculturing and Gram staining after a 5-day protocol were important for the detection of C. neoformans, and Myco/F bottles should be collected for the blood culture of C. neoformans.

Time to Positivity of Cultures Obtained for Periprosthetic Joint Infection

BACKGROUND

Despite its well-established limitations, culture remains the gold standard for microbial identification in periprosthetic joint infection (PJI). However, there are no benchmarks for the time to positivity (TTP) on culture for specific microorganisms. This study aimed to determine the TTP for pathogens commonly encountered in PJI.

METHODS

This retrospective, multicenter study reviewed prospectively maintained institutional PJI databases to identify patients who underwent hip or knee revision arthroplasty from 2017 to 2021 at 2 tertiary centers in the United States and Germany. Only patients who met the 2018 International Consensus Meeting (ICM) criteria for PJI and had a positive intraoperative culture were included. TTP on culture media was recorded for each sample taken intraoperatively. The median TTP was compared among different microbial species and different specimen types. Data are presented either as the mean and the standard deviation or as the median and the interquartile range (IQR).

RESULTS

A total of 536 ICM-positive patients with positive cultures were included. The mean number of positive cultures per patient was 3.9 ± 2.6. The median TTP, in days, for all positive cultures was 3.3 (IQR, 1.9 to 5.4). Overall, gram-negative organisms (TTP, 1.99 [1.1 to 4.1]; n = 225) grew significantly faster on culture compared with gram-positive organisms (TTP, 3.33 [1.9 to 5.8]; n = 1,774). Methicillin-resistant Staphylococcus aureus (TTP, 1.42 [1.0 to 2.8]; n = 85) had the fastest TTP, followed by gram-negative rods (TTP, 1.92 [1.0 to 3.9]; n = 163), methicillin-sensitive Staphylococcus aureus (TTP, 1.95 [1.1 to 3.3] n = 393), Streptococcus species (TTP, 2.92 [1.2 to 4.3]; n = 230), Staphylococcus epidermidis (TTP, 4.20 [2.4 to 5.5]; n = 555), Candida species (TTP, 5.30 [3.1 to 10]; n = 63), and Cutibacterium acnes (TTP, 6.97 [5.9 to 8.2]; n = 197). When evaluating the median TTP according to specimen type, synovial fluid (TTP, 1.97 [1.1 to 3.1]; n = 112) exhibited the shortest TTP, followed by soft tissue (TTP, 3.17 [1.4 to 5.3]; n = 1,199) and bone (TTP, 4.16 [2.3 to 5.9]; n = 782).

CONCLUSIONS

To our knowledge, this is the first study to examine the TTP of common microorganisms that are known to cause PJI. Increased awareness of these data may help to guide the selection of appropriate antimicrobial therapy and to predict treatment outcomes in the future. Nonetheless, additional studies with larger cohorts are needed to validate these benchmarks.

LEVEL OF EVIDENCE

Diagnostic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Clinical Impact of Time-to-Positivity of Blood Cultures on Mortality in Patients with Pseudomonas aeruginosa Bacteremia

OBJECTIVES

To investigate the impact of the time-to-positivity of blood cultures (TTP) on 30-day mortality in patients with Pseudomonas aeruginosa (PA) bacteremia.

METHODS

All non-duplicated episodes of PA monomicrobial bacteremia in adult patients from January 2013 to February 2020 were analysed. Epidemiological and clinical data were collected. TTP for PA isolates was automatically recorded. Multivariate analysis identified factors predicting 30-day overall mortality.

RESULTS

A total of 328 patients were identified. The median TTP for PA isolates was 15 h (IQR 12-18 h). All MDR/XDR episodes were positive within the first 36 h. The 30-day mortality rate was 32.3%. The best cut-off value of the TTP for predicting mortality was 16 h (AUC 0.62, 95% CI 0.56-0.67, P=0.001). The 30-day mortality rate was significantly higher in the TTP ≤16 h group (41.0% versus 19.5%, P<0.001). In a multivariate analysis, severe neutropenia (aOR 2.67, 95% CI 1.4-5.09, P=0.002), septic shock (aOR 3.21, 95% CI 1.57-5.89, P<0.001), respiratory source (aOR 4.37, 95% CI 2.24-8.52, P<0.001), nosocomial acquisition (aOR 1.99, 95% CI 1.06-3.71, P=0.030), TTP≤ 16 h (aOR 2.27, 95% CI 2.12-4.25, P=0.010) and MDR/XDR phenotype (aOR 2.54, 95% CI 1.38-4.67, P=0.002) were independently associated with 30-day mortality.

CONCLUSIONS

A short TTP (≤16 h) was independently associated with increased 30-day mortality. After local validation, this routinely microbiological parameter might be useful for guiding empirical antipseudomonal therapies and supporting the close monitoring of patients with PA bacteremia.

Skin bacterial richness and diversity in intensive care unit patients with severe pneumonia

OBJECTIVES

Patients with severe pneumonia admitted to the intensive care unit (ICU) have a high risk of mortality, and the microbiome is likely to affect the outcome of such patients. However, the composition of the skin microbiota of ICU patients with severe pneumonia remains unclear. In this study, on the basis of 16S ribosomal ribonucleic acid sequencing, we explored the difference in skin bacterial richness and diversity between the ICU patient group (PG) with severe pneumonia and the healthy control group (CG).

METHODS

The diversity index and taxonomic distribution of skin bacteria were analyzed using the Quantitative Insights Into Microbial Ecology (QIIME) bioinformatics pipeline. Blood, endotracheal aspirate, and bronchoalveolar lavage fluid samples were collected from the same PG subjects for culture.

RESULTS

Compared with the CG, the diversity of skin bacteria in the PG decreased significantly. Staphylococcus, Acinetobacter, Stenotrophomonas, Enterococcus, Halomonas, and Brevibacillus were differentially abundant in the PG, and most of these bacteria were also identified in the cultures of upper respiratory tract samples of the same PG.

CONCLUSION

We provide evidence that healthcare-associated infection in ICU patients with severe pneumonia is strongly associated with skin microbiota, which necessitates the prevention and control of skin bacterial pathogens for these patients.

Time to blood culture positivity- an independent predictor of mortality in Streptococcus pyogenes bacteraemia

Background

Streptococcus pyogenes bacteremia is a severe condition with high mortality. Time to blood culture positivity (TTP) is known to predict the outcome in bacteremia with other pathogens. This study aimed to determine the association between TTP and outcome in S pyogenes bacteremia.

Methods

This retrospective observational cohort study comprised adults with S pyogenes bacteremia, identified through the laboratory database between 2015 and 2018, in the Region of Skåne, Sweden. Correlations between TTP and outcomes were investigated. Primary outcome was death within 30 days, and secondary outcomes were presence of sepsis or disease deterioration within the first 48 hours.

Results

A total of 347 episodes of S pyogenes bacteremia were identified, of which 61 were excluded, resulting in 286 included episodes. Median TTP was 10.4 (interquartile range, 8.4–11.4) hours. Thirty-day mortality was 10%. Median TTP was shorter in patients who died within 30 days compared to survivors (8.6 vs 10.4 hours; P < .001). In a multivariable logistic regression, shorter TTP was associated with 30-day mortality when adjusting for age, Charlson Comorbidity Index, and focus of infection (odds ratio, 3.7 [95% confidence interval, 1.2–11.3]; P = .02). There was no statistically significant difference in TTP between patients with sepsis within 48 hours and those who did not have sepsis. Additionally, there was no statistically significant difference in TTP between patients with disease deterioration compared to those who did not deteriorate.

Conclusions

Knowledge on TTP might be a tool to determine the prognosis of a given patient with S pyogenes bacteremia.

Quantitative Fluorescence In Situ Hybridization (FISH) of Magnetically Confined Bacteria Enables Early Detection of Human Bacteremia

The current diagnosis of bacteremia mainly relies on blood culture, which is inadequate for the rapid and quantitative determination of most bacteria in blood. Here, a quantitative, multiplex, microfluidic fluorescence in situ hybridization method (μFISH) is developed, which enables early and rapid (3-h) diagnosis of bacteremia without the need for prior blood culture. This novel technology employs mannose-binding lectin-coated magnetic nanoparticles, which effectively opsonize a broad range of pathogens, magnetically sequestering them in a microfluidic device. Therein, μFISH probes, based on unique 16S rRNA sequences, enable the identification and quantification of sequestered pathogens both in saline and whole blood, which is more sensitive than conventional polymerase chain reaction. Using μFISH, Escherichia coli (E. coli) is detected in whole blood collected from a porcine disease model and from E. coli-infected patients. Moreover, the proportion of E. coli, relative to other bacterial levels in the blood, is accurately and rapidly determined, which is not possible using conventional diagnostic methods. Blood from E. coli-infected patients is differentiated from healthy donors' blood using cutoff values with a 0.05 significance level. Thus, μFISH is a versatile method that can be used to rapidly identify pathogens and determine their levels relative to other culturable and nonculturable bacteria in biological samples.

Short time to positivity of blood culture predicts mortality and septic shock in bacteremic patients: a systematic review and meta-analysis

Background

The value of time to positivity (TTP) on diagnosis for catheter-related bloodstream infection and distinguishment on bacteria group and infection source has been investigated. However, the relationship between TTP and patient outcome requires verification, and we performed a systematic review and meta-analysis.

Methods

We searched PubMed, EMBASE, CINAHL, Cochrane Library, Web of Science for publications associated with the topic. We included studies that researched the TTP on predicting patient mortality and septic shock. Quality assessment is performed with Critical Appraisal Skills Programme (CASP). The analysis is performed using Review Manager Version 5.0.24. on articles available for data extraction on the exact population of each outcome group. The existence of publication bias was assessed by funnel plots. Statistical heterogeneity was evaluated using the Cochran Q and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${I}^{2}$$\end{document}I2 statistics. The outcome is reported as an odds ratio. PROSPERO registration: CRD42021272286.

Results

Twenty-four eligible studies were included in our study. Twenty-four in the mortality group and six in the septic shock group. Mortality is significantly associated with the short time to positivity group with an odds ratio of 2.98 (95% CI: 2.25–3.96, p-value < 0.001). The odds ratio for developing septic shock in the short TTP group is 4.06 (95% CI: 2.41–6.84, p-value < 0.001). Subgroup analysis revealed short TTP as a significant predictor of mortality and septic shock in Gram's positive and Gram's negative related bloodstream infections. TTP is not associated with mortality among patients with candidaemia.

Conclusions

Short time to positivity is a reliable marker for patient outcome in certain bacterial species. Studies concerning confounding factors such as the delay in bottle loading and other confounding factors are needed to enhance external validity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07098-8.

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

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

Burden of pneumococcal disease among adults in Southern Europe (Spain, Portugal, Italy, and Greece): a systematic review and meta-analysis

The aim was to summarize pneumococcal disease burden data among adults in Southern Europe and the potential impact of vaccines on epidemiology. Of 4779 identified studies, 272 were selected. Invasive pneumococcal disease (IPD) incidence was 15.08 (95% CI 11.01-20.65) in Spain versus 2.56 (95% CI 1.54-4.24) per 100,000 population in Italy. Pneumococcal pneumonia incidence was 19.59 (95% CI 10.74-35.74) in Spain versus 2.19 (95% CI 1.36-3.54) per 100,000 population in Italy. Analysis of IPD incidence in Spain comparing pre-and post- PCV7 and PCV13 periods unveiled a declining trend in vaccine-type IPD incidence (larger and statistically significant for the elderly), suggesting indirect effects of childhood vaccination programme. Data from Portugal, Greece and, to a lesser extent, Italy were sparse, thus improved surveillance is needed. Pneumococcal vaccination uptake, particularly among the elderly and adults with chronic and immunosuppressing conditions, should be improved, including shift to a higher-valency pneumococcal conjugate vaccine when available.

Time to positivity in bloodstream infection is not a prognostic marker for mortality: analysis of a prospective multicentre randomized control trial

OBJECTIVES

Time to positivity (TTP), calculated automatically in modern blood culture systems, is considered a proxy for microbial load and has been suggested as a potential prognostic marker in bloodstream infections. In this large, multicentre, prospectively collected cohort, our primary analysis aimed to quantify the relationship between the TTP of monomicrobial blood cultures and mortality.

METHODS

Data from a multicentre randomized controlled trial (RAPIDO) in bloodstream infection were analysed. Bloodstream infections were classified into 13 groups/subgroups. The relationship between mortality and TTP was assessed by logistic regression, adjusted for site, organism, and clinical variables, and linear regression was applied to examine the association between clinical variables and TTP. Robustness was assessed by sensitivity analysis.

RESULTS

In total 4468 participants were included in the RAPIDO. After exclusions, 3462 were analysed, with the most common organisms being coagulase-negative staphylococci (1072 patients) and Escherichia coli (861 patients); 785 patients (22.7%) died within 28 days. We found no relationship between TTP and mortality for any groups except for streptococci (odds ratio (OR) with each hour 0.98, 95%CI 0.96-1.00) and Candida (OR 1.03, 95%CI 1.00-1.05). There was large variability between organisms and sites in TTP. Fever (geometric mean ratio (GMR) 0.95, 95%CI 0.92-0.99), age (GMR per 10 years 1.01, 95%CI 1.00-1.02), and neutrophilia were associated with TTP (GMR 1.03, 95%CI 1.02-1.04).

CONCLUSIONS

Time to positivity is not associated with mortality, except in the case of Candida spp. (longer times associated with worse outcomes) and possibly streptococci (shorter times associated with worse outcomes). There was a large variation between median times across centres, limiting external validity.

Short time to blood culture positivity in Enterococcus faecalis infective endocarditis

Time to blood culture positivity (TTP) is an indirect measure of bacterial concentration in blood. A short TTP has been linked to the presence of infective endocarditis (IE) and to poor prognosis in Staphylococcus aureus bacteremia. We analyze factors influencing TTP in bacteremia with Enterococcus faecalis. This retrospective observational study of medical records included adults diagnosed with monomicrobial E. faecalis bacteremia between 2015 and 2018 in the Skåne region (Sweden). For each episode, the shortest TTP was recorded. Median TTP was compared between patients grouped based on age, sex, comorbidity, site of acquisition, and focus of infection. Using a dichotomized TTP (shorter or longer than 12 h), a multivariable logistic regression for factors associated to TTP was performed. The association between TTP and IE or mortality was evaluated. Three hundred sixty-seven episodes with monomicrobial E. faecalis bacteremia with the corresponding TTP were identified. Median TTP for the entire cohort was 11.6 (IQR 9.9–14.1) h and a significantly shorter TTP was noted for episodes which represented IE (n = 55, 9.4 (IQR 6.4–10.6) h). Only IE remained associated with a short TTP (≤ 12 h) in binary logistic regression analysis. Factors associated with IE were investigated and TTP was associated with IE also when adjusted for age, gender, comorbidity, and nosocomial acquisition. There was no association between TTP and mortality. A low TTP is associated with IE in E. faecalis bacteremia and could be used as a help in determining the need for echocardiography in patients with this condition.

New guidelines for severe community-acquired pneumonia

PURPOSE OF REVIEW

We highlight the recent advances in the guidelines for treating patients with severe community-acquired pneumonia (sCAP).

RECENT FINDINGS

sCAP is a significant cause of hospital admissions. We performed an extensive review of the literature, covering studies from the last several years, to summarise the most important points in the diagnosis and treatment of patients hospitalised with sCAP.

SUMMARY

sCAP is associated with a high clinical burden. Therefore, deep knowledge is necessary for its management. In general, diagnosis, treatment and management are based on many published guidelines. However, the mortality rate is still unacceptably high, indicating the need for clear recommendations in the management of patients with sCAP. The choice of empirical antibiotic therapy for sCAP depends on multiple factors, such as national and local antimicrobial susceptibility data and the characteristics of the patients, including their risk factors for acquiring infections caused by multidrug-resistant pathogens. Currently, there are several published international guidelines. The aim of this review is to explore the areas that require further knowledge and new recommendations for current clinical practice.

Time to positivity of Klebsiella pneumoniae in blood culture as prognostic indicator for pediatric bloodstream infections

The aim of this study is to explore the prognostic values and optimal cutoff point of time to positivity (TTP) of blood culture in children with Klebsiella pneumoniae (K. pneumoniae) bloodstream infection. Ninety-four children with K. pneumoniae bloodstream infection hospitalized in Children's Hospital of Chongqing Medical University from April 2014 to January 2019 were enrolled retrospectively. TTP and risk factors were determined and analyzed by receiver operating characteristic (ROC) analysis and logistic regression analysis. The standard cutoff point of TTP was 13 h. Patients in early TTP (≤ 13 h) group had significantly higher in-hospital mortality (37.93% vs 6.15%, P = 0.000), higher incidence of septic shock (44.83% vs 6.15%, P = 0.000), higher proportion of PRISM III scores ≥ 10 (48.28% vs 20.00%, P = 0.005), and higher proportion of hypoalbuminemia on admission (44.83% vs 18.46%, P = 0.008). Multivariate analysis indicated PRISM III scores ≥ 10, early TTP, and hypoalbuminemia on admission were independent risk factors of in-hospital mortality (OR 8.36, 95% CI 1.80-38.92, P = 0.007; OR 5.85, 95% CI 1.33-25.61, P = 0.019; OR 5.73, 95% CI 1.30-25.22, P = 0.021, respectively) and septic shock (OR 14.04, 95% CI 2.63-75.38, P = 0.002; OR 11.26, 95% CI 2.10-60.22, P = 0.005; OR 10.27, 95% CI 2.01-52.35, P = 0.005, respectively).Conclusion: Early TTP (TTP ≤ 13 h), PRISM III scores ≥ 10, and hypoalbuminemia on admission appeared to be associated with worse outcomes for K. pneumoniae bloodstream infection children. What is Known: • Klebsiella pneumoniae bloodstream infection is an important cause of infectious disease morbidity and mortality worldwide in children. • Short duration of time to positivity indicated poor clinical outcomes. What is New: • Time to positivity ≤ 13 h, along with PRISM III scores ≥ 10 and hypoalbuminemia on admission, indicated higher in-hospital mortality and incidence of septic shock in Klebsiella pneumoniae bloodstream infection children. • The cut-off point of TTP in this pediatric study was much longer than that reported in adult patients.

Diagnostic accuracy of time to first positivity of blood cultures for predicting severe clinical outcomes in children with pneumonia-related bacteremia

Early recognition of severe clinical outcomes in children with pneumonia-related bacteremia is vitally important because of the high mortality. This study aims to explore risk factors for severe clinical outcomes in children with pneumonia-related bacteremia and evaluate the value of time to first positive blood cultures (TTFP) in predicting prognosis. Children with pneumonia-related bacteremia in Children’s Hospital of Chongqing Medical University were included (January 2013–May 2019), respectively. TTFP and clinical parameters were collected and analyzed. The area under the curve (AUC)-receiver operating characteristic was used to evaluate the discrimination ability of TTFP. Multivariate logistic regression tests were performed to evaluate the association between TTFP and severe clinical outcomes. A total of 242 children with pneumonia-related bacteremia were included. The least absolute shrinkage and selection operator (LASSO) regression analysis identified TTFP, serum albumin (ALB) and lactic dehydrogenase (LDH) as predictors of in-hospital mortality. Multivariate logistic regression analysis showed that shorter TTFP (OR 0.94; 95% CI 0.89 to 0.97; p<0.01), lower ALB level (OR 0.93; 95% CI 0.89 to 0.98; p<0.01) and higher LDH level (OR 1.001; 95% CI 1.000 to 1.001; p<0.01) were risk factors for in-hospital mortality in children with pneumonia-related bacteremia. AUC of TTFP for predicting in-hospital mortality was 0.748 (95% CI 0.668 to 0.829). Shorter TTFP (≤16 hours) was associated with in-hospital mortality and septic shock. TTFP plays an important role in predicting severe clinical outcomes in children with pneumonia-related bacteremia.

Time to positivity of blood culture is a risk factor for clinical outcomes in Staphylococcus aureus bacteremia children: a retrospective study

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.

Prognostic roles of time to positivity of blood culture in children with Streptococcus pneumoniae bacteremia

We aimed to investigate the relationship between time to positivity (TTP) of blood cultures and clinical outcomes in children with S. pneumoniae bacteremia. Children with S. pneumoniae bacteremia hospitalized in Children's Hospital of Chongqing Medical University from May 2011 to December 2017 were enrolled retrospectively. Overall, 136 children with S. pneumoniae bacteremia were enrolled. The standard cutoff TTP was 12 h. We stated that in-hospital mortality is significantly higher in the early TTP (≤ 12 h) group than that in the late TTP (> 12 h) group (41.70% vs 8.00%, P < 0.001). Septic shock occurred in 58.30% of patients with early TTP and in 21.00% of patients with late TTP (P < 0.001). Independent risk factors of in-hospital mortality and septic shock in children with S. pneumoniae bacteremia included early TTP, need for invasive mechanical ventilation, and PRISM III score ≥ 10. Overall, TTP ≤ 12 h appeared to associate with the worse outcomes for children with S. pneumoniae bacteremia.

Treatment and prevention of invasive pneumococcal disease

Invasive pneumococcal disease is a severe infection that mainly affects patients with associated comorbidity. The paediatric conjugate vaccination has resulted in a change in the adult vaccination strategy. The antibiotic resistance of pneumococcus is not currently a severe problem. Nevertheless, the World Health Organisation has included pneumococcus among the bacteria whose treatment requires the introduction of new drugs, such as ceftaroline and ceftobiprole. Although the scientific evidence is still limited, the combination of beta-lactams and macrolides is recommended as empiric therapy for bacteraemic pneumococcal pneumonia.