The Relationship Between Blood Culture, C-reactive Protein, and Neonatal Sepsis: A Cross-Sectional Study.

Background Sepsis is one of the most common causes of morbidity and mortality in newborns. Diagnosis of neonatal sepsis may be difficult because the clinical presentations are often nonspecific. Neonatal sepsis may have an early onset (zero to three days) or a late onset (four days or later). Onset is most rapid in premature neonates. In this study, we aimed to assess the correlation between positive cultures, high C-reactive protein (CRP) levels, and the diagnosis of neonatal sepsis. Methodology This descriptive, prospective, cross-sectional study was undertaken over four months starting from December 15, 2019, to April 15, 2020, in Atbara Teaching Hospital, Sudan. Data were collected from 71 patients. CRP levels were measured, and blood cultures were performed. Results High CRP level >10 mg/L was seen in patients having positive blood culture (55.3%), mainly in preterm babies (CRP >10 mg/dL (61.1%), positive culture (55.6%)) and very low birth weight babies (CRP >10 mg/dL (83.3%) and positive culture (67%)). Conclusions Our findings suggest that Klebsiella is an important cause of neonatal sepsis. CRP was positive in babies mainly with proven sepsis. There is a high correlation between CRP and blood culture in patients with neonatal sepsis which may give access to remodeling the prioritization of the management options in the clinical setting.

A Day Saved is a Life Saved: Direct Antimicrobial Susceptibility Testing from Positively Flagged Blood Culture Bottles and their Concordance with the Routine Method.

BACKGROUND: Sepsis is a major health problem worldwide and is associated with high morbidity and mortality with every hour delay in initiation of therapy. A conventional method of blood culture and Antimicrobial Susceptibility Testing (AST) takes around 48-72 hours. Empirical antibiotics need to be administered until the sensitivity report is made available. It has been estimated that 20-50% of the empirical antibiotics are inappropriate, resulting in prolonged hospital stays, adverse effects, and emergence of drug resistance. Additionally, this also puts an extra financial burden on both the patients and healthcare settings. Performing direct Antimicrobial Sensitivity Testing (dAST) is an important tool to reduce turn-around time (TAT) by at least 18-24 hours, thus reducing morbidity and mortality among critically ill patients. METHODS: Direct AST (dAST) was performed from the positively flagged blood culture bottles received between December, 2021 to May, 2022 from Intensive Care Units (ICUs) on MuellerHinton Agar (MHA) using four drops of withdrawn blood. dAST was performed for six drugs: Ceftriaxone-30 µg (CTR), Piperacillin/Tazobactam-100/10 µg (PIT), Meropenem-10 µg (MRP), Ciprofloxacin-5 µg (CIP), Aztreonam-30 µg (AT), and Colistin (CL). The zone of inhibition was interpreted as per CLSI M100 ed32, 2022 guidelines. A parallel conventional method was also performed to examine for categorical agreement and disagreement. Identification was carried out using MALDI-TOF MS from the colonies that appeared on the dAST plate on the subsequent day. RESULTS: A total of 162 positively flagged blood culture bottles were included in the study. The majority of the Gram-negative organisms were from Enterobacterales (n=109), followed by Acinetobacter spp. (n=28) and Pseudomonas aeruginosa (n=25). Out of the 972 isolate-antimicrobial combinations, overall Categorical Agreement (CA) was seen in 936 (96.3%), whereas disagreement was observed in 36 with minor error (mE) in 21 (2.2%), major error (ME) in 7 (0.7%), and very major error (VME) in 8 (0.8%) when compared to the routine method. Categorical agreement (CA) of > 99% was seen in ceftriaxone (CTR) and ciprofloxacin (CIP). In comparison, the lowest CA was observed with meropenem (MRP) at 92%. Colistin dAST was performed using the E-strip method, and the result obtained was highly convincing, with an overall disagreement of only 1.2%. CONCLUSION: Rapid dAST from positively flagged blood culture bottles proved to significantly reduce the TAT from the time of sample collection to the first availability of antimicrobial susceptibility report with excellent categorical agreement of > 95% using the conventional disc diffusion method. Results obtained were within the acceptance criteria set by U. S. Food and Drug Administration (FDA) guidelines of > 90% categorical agreement for a new method. We were able to obtain excellent concordance for colistin using the E-strip method. Performing dAST not only saves a "day", but its proper implementation would save a "life".

[Urosepsis: pathophysiology, diagnosis, and management-an update]. / Urosepsis: Pathophysiologie, Diagnose und Management ­ ein Update.

Urinary tract infections vary widely in their clinical spectrum, ranging from uncomplicated cystitis to septic shock. Urosepsis accounts for 9-31% of all cases of septicemia and is often associated with nosocomial infections. A major risk factor for urosepsis is the presence of obstructive uropathy, caused by conditions such as urolithiasis, tumors, or strictures. The severity and course of urosepsis depend on both the virulence of the pathogen and the patient's specific immune response. Prompt therapy, including antimicrobial treatment and eradication of the infection source, along with supportive measures for circulatory and respiratory stabilization, and adjunctive therapies such as hemodialysis and glucocorticoid therapy, is crucial. Due to demographic changes, an increase in cases of urosepsis is expected-thus, it is of utmost importance for urologists to be familiar with targeted diagnostics and effective treatment.

Finding significant pathogens in blood cultures in children: Should we set the timer to 36 hours?

Background: Knowledge of time to positivity (TTP) for blood cultures is useful to assess timing of discontinuation of empiric antimicrobials for suspected bacteremia with no focus. Methods: An audit of positive blood cultures from the Children's Hospital of Eastern Ontario (CHEO) from November 1, 2019, to October 31, 2020, was performed to determine TTP, defined as the start of incubation to a positive signal from automated incubators. Results: Three hundred seventy-six positive blood cultures were identified from 248 patients (average age: 6.27 [SD 6.24] years). Of these, 247 isolates were speciated; 90 (36.4%) were definitive/probable (DP) pathogens (median TTP 12.75 hours) and 157 (63.6%) possible/probable (PP) contaminants (median TTP 24.08 hours). At each time point, the adjusted rate of positive blood culture was significantly higher for DP pathogens compared to PP contaminants (hazard ratio [HR] 1.80 [95% CI 1.37, 2.36]) and for children ≤27 days old compared to the oldest age group (HR 1.94 [95% CI 1.19, 3.17]). By 36 hours, the proportion of positive cultures was significantly higher in the youngest age group (≤27 days) compared with the 3-11 years old age group (91.7% [95% CI 68.6%, 97.8%] versus 58.2% [95% CI 46.91%, 68.06%]). Conclusion: Across all ages, the TTP was significantly shorter for blood cultures with DP pathogens compared to those with PP contaminants (HR 1.80 [95% CI 1.37, 2.36]). In newborns, 90% of blood cultures were positive by 36 hours supporting this re-assessment time for empiric antimicrobials. TTP was longer in children ≥12 months, possibly related to other factors such as blood culture volume.

Historique: Il est utile de connaître le délai de positivité (DdP) des hémocultures pour évaluer le moment de mettre un terme aux antimicrobiens empiriques en cas de présomption de bactériémie sans source apparente. Méthodologie: Les chercheurs ont procédé à un audit des hémocultures positives du Centre hospitalier pour enfants de l'est de l'Ontario (CHEO) entre le 1er novembre 2019 et le 31 octobre 2020 pour déterminer le DdP, défini comme la période entre le début de l'incubation et le signal positif d'incubateurs automatisés. Résultats: Les chercheurs ont extrait 376 hémocultures positives provenant de 248 patients (d'un âge moyen de 6,27 ± 6,24 ans). De ce nombre, ils ont différencié 247 isolats, dont 90 (36,4 %) étaient des agents pathogènes confirmés ou probables (CP) (DdP médian de 12,75 heures) et 157 (63,6 %), des contaminants possibles ou probables (PP) (DdP médian de 24,08 heures). À chaque point temporel, le taux corrigé d'hémocultures positives était sensiblement plus élevé à l'égard des agents pathogènes CP que des contaminants PP (rapport de risque instantanés [RRI] : 1,80 [IC à 95 % 1,37,2,36]) et des nouveau-nés de 27 jours de vie ou moins que des enfants plus âgés (RRI 1,94 [IC à 95 % 1,19,3,17]). Au bout de 36 heures, la proportion de cultures positives était sensiblement plus élevée dans le groupe le plus jeune (27 jours de vie ou moins) que dans celui des enfants de trois à 11 ans, soit de 91,7 % (IC à 95 % 68,6 %, 97,8 %) par rapport à 58,2 % (IC à 95 % 46,91 %, 68,06 %). Conclusion: À tout âge, le DdP était sensiblement plus court, à l'égard des hémocultures contenant des agents pathogènes CP que des contaminants PP (RRI 1,80 [IC à 95 % 1,37,2,36]). Chez les nouveau-nés, 90 % des hémocultures sont positives au bout de 36 heures, ce qui appuie ce moment pour réévaluer la prise d'antimicrobiens empiriques. Le DdP était plus long chez les enfants âgés de plus de 12 mois, peut-être à cause d'autres facteurs comme le volume de l'hémoculture.

Changes in clinical parameters and inflammatory markers after blood culture collection facilitate early identification of positive culture in adult patients with COVID-19 and clinically suspected bloodstream infection.

OBJECTIVE: We explored whether changes in clinical parameters and inflammatory markers can facilitate early identification of positive blood culture in adult patients with COVID-19 and clinically suspected bloodstream infection (BSI). METHODS: This single-center retrospective study enrolled 20 adult patients with COVID-19 admitted to the intensive care unit who underwent blood culture for clinically suspected BSI (February 2020-November 2021). We divided patients into positive (Pos) and negative blood culture groups. Clinical parameters and inflammatory markers were obtained from medical records between blood culture collection and the first positive or negative result and compared between groups on different days. RESULTS: Patients in the positive culture group had significantly older age and higher D-dimer, immunoglobulin 6 (IL-6), and Sequential Organ Failure Assessment score as well as lower albumin (ALB). The area under the receiver operating characteristic curve (AUC) was 0.865 for IL-6, D-dimer and ALB on the first day after blood culture collection; the AUC was 0.979 for IL-6, IL-10, D-dimer, and C-reactive protein on the second day after blood culture collection. CONCLUSION: Changes in clinical parameters and inflammatory markers after blood culture collection may facilitate early identification of positive culture in adult patients with COVID-19 and clinically suspected BSI.

Make modern microbiology matter more in the 2023 ESC guidelines for the management of infective endocarditis.

The ESC 2023 guidelines for the management of endocarditis stress that a multidisciplinary approach is needed to manage patients with infective endocarditis (IE). In our view the guidelines do not include the relevant perspectives from modern microbiology. The diagnostic criteria for IE were changed in the ESC 2023 guidelines and many IE-causing pathogens are either not clearly defined or not even mentioned. Moreover, the improved understanding of the relation between bacterial species and the risk for IE has not been implemented. The guidelines give detailed, and in our view not correct, instructions about diagnostic testing in blood culture negative IE without presenting proper evidence. Other important diagnostic aspects such as the value of repeated blood cultures and incubation time for blood cultures are not discussed. We believe that a multidisciplinary collaboration, including microbiologists, would have improved these guidelines and we hope for a future harmonization of diagnostic criteria for IE.

Does it matter who performs blood culture collection? Results of a survey assessing phlebotomist, nurse, and resident knowledge of blood culture collection protocols.

Blood cultures are the primary method for diagnosing bloodstream infections. However, blood culture contamination (BCC) can lead to unnecessary antibiotic treatment, additional tests, and extended patient time in the hospital. The aim of this quality improvement project was to evaluate healthcare workers' knowledge of blood culture collection protocols and evaluate the blood culture contamination rates of laboratory and non-laboratory staff. We performed a retrospective review of contaminated cultures between May 2021 and April 2022, and anonymous surveys were distributed to assess staff knowledge of proper blood culture collection protocols. Laboratory staff (phlebotomy) had an overall BCC rate of 4.6% compared to a non-laboratory staff (nurses, residents, and medical students) rate of 9.7% (p < 0.0001). On the survey, phlebotomists had the best score (89% correct), followed by nurses (76%) and residents and medical students (64%). These data suggest that blood culture protocol knowledge and BCC rates may be related, with phlebotomists scoring highest on the knowledge survey and demonstrating the lowest contamination rates.

Evaluation of Direct Antimicrobial Susceptibility Testing from Positive Flagged Blood Cultures in Sepsis Patients.

Background: Presently, many laboratories are equipped with automated system for antimicrobial susceptibility testing (AST) for minimum inhibitory concentration-based reporting which enables the clinician to choose the right antimicrobial for timely treatment of sepsis. The study aimed to assess performance of direct AST from blood culture positive broth using automated AST system for accuracy and time taken to release the report. Materials and methods: The present study conducted in a 25-bedded ICU in North India for 12 months. Single morphotype of bacteria on gram stain from positively flagged blood culture bottles were included, which was directly identified (using an in-house protocol) with MALDI-TOF-MS from positive blood culture broths. DAST was carried out from 200 such blood culture broths and results were compared with reference AST (RAST) which was also done using VITEK-2 using overnight grown bacterial colonies as per standard protocol. Results: Among 60 isolates of Enterobacterales, 99% categorical agreement for both E. coli and K. pneumoniae observed by two methods were tested for AST. Among non-fermenters, Pseudomonas aeruginosa showed a categorical agreement of 99.6%, as compared with Acinetobacter spp. and exotic GNBs, which showed 95-96% agreement. A significant difference of 18-24 hours was noted in time to release the report between DAST and RAST, for GNB and GPC both. Conclusion: Direct AST from positive flagged blood culture bottles can significantly reduce the time to release the bacterial susceptibility report by up to 24 hours, at the same time maintaining the accuracy. How to cite this article: Singh V, Agarwal J, Nath SS, Sharma A. Evaluation of Direct Antimicrobial Susceptibility Testing from Positive Flagged Blood Cultures in Sepsis Patients. Indian J Crit Care Med 2024;28(4):387-392.

A pilot study investigating severe community-acquired febrile illness through implementation of an innovative microbiological and nucleic acid amplification testing strategy in Timor-Leste (ISIN-MANAS-TL).

Objectives: Acute febrile illness (AFI) causes significant health-seeking, morbidity, and mortality in Southeast Asia. This pilot study aimed to describe presentation, etiology, treatment, and outcomes of patients with AFI at one hospital in Timor-Leste and assessing the feasibility of conducting larger studies in this setting. Methods: Patients attending Hospital Nacional Guido Valadares with tympanic or axillary temperature ≥37.5°C in whom a blood culture was taken as part of routine clinical care were eligible. Participants were followed up daily for 10 days and again after 30 days. Whole blood was analyzed using a real-time quantitative polymerase chain reaction assay detecting dengue virus serotypes 1-4 and other arthropod-borne infections. Results: A total of 82 participants were recruited. Polymerase chain reaction testing was positive for dengue in 14 of 82 (17.1%) participants and blood culture identified a bacterial pathogen in three of 82 (3.7%) participants. Follow-up was completed by 75 of 82 (91.5%) participants. High rates of hospital admission (58 of 82, 70.7%), broad-spectrum antimicrobial treatment (34 of 82, 41.5%), and mortality (9 of 82, 11.0%) were observed. Conclusions: Patients with AFI experience poor clinical outcomes. Prospective observational and interventional studies assessing interventions, such as enhanced diagnostic testing, clinical decision support tools, or antimicrobial stewardship interventions, are required and would be feasible to conduct in this setting.

Anaerobic gram-negative rod bacteremia as a marker of gastrointestinal cancer in Japanese patients: a single-center retrospective study.

BACKGROUND: Gram-negative rod (GNR) bacteremia has been suggested as a clinical marker of occult cancer; however, no studies are available in this regard in the Japanese population. Here, we investigated the risk factors for gastrointestinal cancer with GNR bacteremia. METHODS: Patients with GNR bacteremia admitted to St. Luke's International Hospital between January 2011 and July 2021 were included. The clinical data of patients with and without cancer, 1 year before and after GNR bacteremia diagnosis, were compared. Univariate analysis was performed using χ2 and Fisher's exact tests for categorical variables and the Mann-Whitney U test for continuous variables, while multivariable analysis was performed using logistic regression analysis, and a P of <0.05 was considered statistically significant. RESULTS: Of 2,296 GNR bacteremia-positive patients, 96 were associated with gastrointestinal cancer, and univariate analysis showed significant differences between the gastrointestinal cancer and comparison groups in terms of mean body mass index (BMI; 20.5 vs. 21.8 kg/m2 ), Enterobacterales detection (64.6% vs. 81.3%), and anaerobic GNR detection (24.0% vs. 8.5%). Thirty-five (36%) and 61 (64%) patients had upper and lower gastrointestinal cancer, respectively. There were 23 patients with anaerobic GNR bacteremia related to 24 strains (upper and lower gastrointestinal cancer, 5 and 18 cases, respectively). Multivariate analysis identified anaerobic GNR [odds ratio, 3.440; 95% confidence interval (CI): 2.085-5.675, P<0.001] as a significant risk factor for cancer. CONCLUSIONS: Anaerobic GNR in blood cultures may be a risk factor for gastrointestinal cancer. Therefore, it is necessary consider cancer workup, such as endoscopy, for patients with anaerobic GNR bacteremia.

Clinical and economic evaluation of blood culture whole process optimization in critically ill adult patients with positive blood cultures.

Optimizing blood culture processing is important to ensure bloodstream infections are accurately diagnosed while minimizing adverse events caused by antibiotic abuse. We evaluated the impact of optimized blood culture processes on antibiotic use, clinical outcomes and economics in intensive care unit (ICU) patients with positive blood cultures. From March 2020 to October 2021, our microbiology laboratory implemented a series of improvement measures, including the clinical utility of Fastidious Antimicrobial Neutralization (FAN® PLUS) bottles for the BacT/Alert Virtuo blood culture system, optimization of bottles reception, graded reports and an upgraded Laboratory Information System. A total of 122 ICU patients were included in the pre-optimization group from March 2019 to February 2020, while 179 ICU patients were included in the post-optimization group from November 2021 to October 2022. Compared with the pre-optimization group, the average reporting time of identification and antimicrobial sensitivity was reduced by 16.72h in the optimized group. The time from admission to targeted antibiotic therapy within 24 h after receiving both the Gram-stain report and the final report were both significantly less in the post-optimization group compared to the pre-optimization group. The average hospitalization time was reduced by 6.49 days, the average antimicrobial drug cost lowered by $1,720.85 and the average hospitalization cost by $9,514.17 in the post-optimization group. Optimizing blood culture processing was associated with a significantly increased positive detection rate, a remarkable reduction in the hospital length of stay and in hospital costs for patients in the ICU with bloodstream infections.

Evaluation of three protocols for direct susceptibility testing for Gram-negative rods from flagged positive blood culture bottles.

Bloodstream infections are associated with high mortality, which can be reduced by targeted antibiotic therapy in the early stages of infection. Direct antibiotic susceptibility testing (AST) from flagged positive blood cultures may facilitate the administration of early effective antimicrobials much before the routine AST. This study aimed to evaluate three different direct AST protocols for Gram-negative rods from flagged positive blood culture broths. Blood culture broths showing Gram-negative rods only were subjected to direct AST by Clinical and Laboratory Standards Institute-recommended direct disk diffusion (protocol A). Additionally, automated AST (protocol B) and Kirby-Bauer disk diffusion (protocol C) were performed with standard inoculum prepared from bacterial pellets obtained by centrifuging blood culture broths in serum separator vials. For comparison, conventional AST of isolates from solid media subculture was also performed with Kirby-Bauer disk diffusion (reference standard) and the automated method. Overall, categorical agreements of protocols A, B, and C were 97.6%, 95.7%, and 95.9%, respectively. Among Enterobacterales, minor error, major error, and very major error rates of protocol B were 3.5%, 0.36%, and 0.43%, respectively, whereas minor error, major error, and very major error rates of protocol C were 3.4%, 0.72%, and 0.21%, respectively, and among non-fermenters, protocol B had a minor error rate of 6.5%, and protocol C had a minor error rate of 4.1% and major error rate of 1.9%. All three direct AST protocols demonstrated excellent categorical agreements with the reference method. Performance of protocols B and C between Enterobacterales and non-fermenters was not statistically different. IMPORTANCE: Bloodstream infections are associated with high mortality that can be reduced by targeted antibiotic therapy in the early stages of infection. Direct antibiotic susceptibility testing (AST) from flagged positive blood cultures may facilitate the administration of early effective antimicrobials much before the routine AST. Clinical and Laboratory Standards Institute-recommended direct AST can be performed with a limited number of antibiotic disks only. On the other hand, using an automated system for direct AST will not only allow effective laboratory workflow with reduced turnaround time but also provide the minimum inhibitory concentration values of tested antibiotics. However, using expensive automated systems for direct AST may not be feasible for resource-limited laboratories. Therefore, in this study, we aimed to evaluate the CLSI-recommended method and two other direct AST protocols (one with an automated system and the other with disk diffusion) for Gram-negative rods from flagged positive blood cultures.

Stop in Time: How to Reduce Unnecessary Antibiotics in Newborns with Late-Onset Sepsis in Neonatal Intensive Care.

The fear of missing sepsis episodes in neonates frequently leads to indiscriminate use of antibiotics, and prescription program optimization is suggested for reducing this inappropriate usage. While different authors have studied how to reduce antibiotic overprescription in the case of early onset sepsis episodes, with different approaches being available, less is known about late-onset sepsis episodes. Biomarkers (such as C-reactive protein, procalcitonin, interleukin-6 and 8, and presepsin) can play a crucial role in the prompt diagnosis of late-onset sepsis, but their role in antimicrobial stewardship should be further studied, given that different factors can influence their levels and newborns can be subjected to prolonged therapy if their levels are expected to return to zero. To date, procalcitonin has the best evidence of performance in this sense, as extrapolated from research on early onset cases, but more studies and protocols for biomarker-guided antibiotic stewardship are needed. Blood cultures (BCs) are considered the gold standard for the diagnosis of sepsis: positive BC rates in neonatal sepsis workups have been reported as low, implying that the majority of treated neonates may receive unneeded drugs. New identification methods can increase the accuracy of BCs and guide antibiotic de-escalation. To date, after 36-48 h, if BCs are negative and the baby is clinically stable, antibiotics should be stopped. In this narrative review, we provide a summary of current knowledge on the optimum approach to reduce antibiotic pressure in late-onset sepsis in neonates.

The Use of CHROMID® Colistin R for the Detection of Colistin-Resistant Gram-Negative Bacteria in Positive Blood Cultures.

The aim of this study was to assess the utility of CHROMID® Colistin R for direct detection of colistin-resistant Gram-negative bacteria from positive blood cultures. A total of 390 blood cultures from hospitalised patients containing Gram-negative bacteria were included in this study. These blood cultures were referred to clinical laboratories in the United Kingdom and Türkiye. A further 16 simulated positive blood culture bottles were included that contained a range of colistin-resistant strains as well as susceptible control strains. Fluid from each positive blood culture was diluted 1/200 in saline and 10 µL aliquots cultured onto cystine-lactose-electrolyte-deficient agar and CHROMID® Colistin R. All recovered bacteria were identified, and for Gram-negative bacteria, their minimum inhibitory concentration of colistin was measured using the broth microdilution method. From a total of 443 Gram-negative isolates, 57 colistin-resistant isolates were recovered, of which 53 (93%) grew on CHROMID® Colistin R within 18 h. Of the 377 isolates determined to be colistin-susceptible, only 9 isolates were able to grow, including 6 isolates of Pseudomonas aeruginosa. For positive blood cultures that are shown to contain Gram-negative bacteria, culture on CHROMID® Colistin R is a useful diagnostic tool to detect susceptibility or resistance to colistin within 18 h.

Hungatella hathewayi bacteremia due to acute appendicitis: A case report and a narrative review.

Hungatella species, including Hungatella hathewayi and Hungatella effluvii, previously identified as part of the Clostridium genus, are anaerobic bacteria primarily residing in the gut microbiome, with infrequent implications in human infections. This article presents the case of an 87-year-old Asian male admitted for a hyperosmolar hyperglycemic state with septic shock secondary to Hungatella hathewayi bacteremia originating from acute appendicitis. Remarkably, the bacterium was detected in the blood 48 hours before the emergence of clinical and radiographic evidence of acute appendicitis. Additionally, we conducted a literature review to identify all documented human infections caused by Hungatella species. Timely microbial identification in such cases is essential for implementing targeted antibiotic therapy and optimizing clinical outcomes.

Evaluating Clinical Prediction Rules for Bacteremia Detection in the Emergency Department: A Retrospective Review.

BACKGROUND: Bacteremia is a major cause of morbidity. Blood cultures are the gold standard for diagnosing bacteremia. OBJECTIVE: To compare previously published clinical decision rules for predicting a true positive blood culture (bacteremia) in the emergency department. METHODS: Retrospective analysis of medical records of patients who had a blood culture performed in a tertiary hospital emergency department in 2020 (12 months). Positive blood cultures were compared with randomly selected negative blood cultures (1:4 ratio). Blood cultures were analyzed per patient presentation. Clinical data from patient presentations were extracted and appraised against the modified-Shapiro (mShapiro) rule and systemic inflammatory response syndrome (SIRS) criteria to calculate diagnostic accuracy to detect bacteremia. RESULTS: During the study period, 3870 blood cultures were taken from 2921 patients: 476 (12.3%) cultures were positive for bacterial growth, from 421 individual patient presentations (10 excluded as incomplete data). Of included patients, 338 were true positives and 73 contaminates, these were compared with 1446 patients with negative blood culture presentations. Evaluating mShapiro's rule and SIRS criteria to detect bacteremia vs. no bacteremia (negative + contaminated cultures) had a sensitivity of 94.4% (95% confidence interval [CI] 91.4-96.4%) and 84.9% (95% CI 80.7-88.3%), respectively, and a specificity of 37.9% (95% CI 35.5-40.1%) and 33.8% (95% CI 31.5-36.3%), respectively. Both had a high negative predictive value for bacteremia of 96.8% (95% CI 95.1-98.0) and 91.0% (95% CI 88.3-93.1) for mShapiro's rule and SIRS criteria, respectively. CONCLUSIONS: In this cohort, mShapiro's rule performed better than the SIRS criteria at predicting bacteremia.

Performance evaluation of machine-assisted interpretation of Gram stains from positive blood cultures.

Manual microscopy of Gram stains from positive blood cultures (PBCs) is crucial for diagnosing bloodstream infections but remains labor intensive, time consuming, and subjective. This study aimed to evaluate a scan and analysis system that combines fully automated digital microscopy with deep convolutional neural networks (CNNs) to assist the interpretation of Gram stains from PBCs for routine laboratory use. The CNN was trained to classify images of Gram stains based on staining and morphology into seven different classes: background/false-positive, Gram-positive cocci in clusters (GPCCL), Gram-positive cocci in pairs (GPCP), Gram-positive cocci in chains (GPCC), rod-shaped bacilli (RSB), yeasts, and polymicrobial specimens. A total of 1,555 Gram-stained slides of PBCs were scanned, pre-classified, and reviewed by medical professionals. The results of assisted Gram stain interpretation were compared to those of manual microscopy and cultural species identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The comparison of assisted Gram stain interpretation and manual microscopy yielded positive/negative percent agreement values of 95.8%/98.0% (GPCCL), 87.6%/99.3% (GPCP/GPCC), 97.4%/97.8% (RSB), 83.3%/99.3% (yeasts), and 87.0%/98.5% (negative/false positive). The assisted Gram stain interpretation, when compared to MALDI-TOF MS species identification, also yielded similar results. During the analytical performance study, assisted interpretation showed excellent reproducibility and repeatability. Any microorganism in PBCs should be detectable at the determined limit of detection of 105 CFU/mL. Although the CNN-based interpretation of Gram stains from PBCs is not yet ready for clinical implementation, it has potential for future integration and advancement.

Early assessment of blood culture negativity as a potential support tool for antimicrobial stewardship.

Objective: To assess whether 48-h negative blood culture (BC) bottles are still negative at the classic 120-h incubation endpoint and whether 48 h might be the time to make antimicrobial therapy decisions. Methods: Data from the first collected bottles from bloodstream infection (BSI) episodes of single patients were retrospectively analyzed. Probabilities of bottles being negative at the classic endpoint were calculated from 0 to 120 h of incubation. Results: Among BC-negative episodes (4018/4901 [82.0%]), most (2097/4018 (52.2%) occurred in medicine patients. At 48 h, probability was 100.0% (95% CI, 99.9-100.0) for all 4018 patients. Of these, 1244 (31.0%) patients remained on antibiotics until 120 h. Excluding 401 (32.2%) patients who received antibiotics for another (non-bloodstream) infection, 843 (67.8%) of 1244 patients could have merited early (48-h) discontinuation of antibiotics. Stopping treatment in these patients would have led to saving 5201 days of access (943 [18.1%] days), watch (3624 [69.7%] days), or reserve (634 [12.2%]) AWaRe groups' antibiotics, which correspond to 65.6% (5201/7928) of days of administered antibiotics in all 1244 patients. Conclusion: As an early indicator of BC negativity, the 48-h endpoint could reliably support antimicrobial stewardship, but the clinical judgment remains imperative especially when BSI is highly suspected.