Culture Bottles Research Articles

Vertebral osteomyelitis caused by Campylobacter jejuni in an immunocompetent patient

BackgroundCampylobacter jejuni is the leading cause of human bacterial gastroenteritis worldwide. However, systemic infection with C. jejuni is uncommon, and osteomyelitis caused by C. jejuni is extremely rare. Cultivation from spinal bone biopsies has not previously been reported in the literature.Case presentationA 79-year-old immunocompetent male was admitted to the emergency department at Aalborg University Hospital in Denmark with lower back pain, fever and diarrhoea. A FecalSwab obtained upon admission was PCR-positive for Campylobacter spp, while an aerobic blood culture bottle was positive for C. jejuni (Time to detection: 70.4 h). A MRI of columna totalis showed osteomyelitis at L1/L2 with an epidural abscess from L1 to L2 with compression of the dura sack. The patient underwent spinal surgery with spondylodesis and decompression of L1/L2. The surgery was uncomplicated and the discus material was also culture positive for C. jejuni. The patient was treated with meropenem for a total duration of four weeks, followed by four weeks of oral treatment with clindamycin in tapered dosage. The patient recovered quickly following surgery and targeted antibiotic treatment with decreasing lumbar pain and biochemical response and was fully recovered at follow-up three months after end of treatment.ConclusionsWhile C. jejuni osteomyelitis is rare, it should still be suspected as a possible causative bacterial aetiology in patients with vertebral osteomyelitis, in particular when symptoms of diarrhoea is involved in the clinical presentation. Susceptibility testing is crucial due to emerging resistance, and targeted treatment strategies should rely upon such tests.

Prevalence of Bacteremia Due to Streptococcus/Enterococcus Species at an Academic/Community Health System Over a Five Year Period

Abstract Timely surveillance of bacteremia is important for identifying emerging pathogens and to implement effective antimicrobial strategies and public health measures. Organisms in the genera Streptococcus and Enterococcus are often the cause of bacteremia and merit particular attention. The objective of this study was to determine the prevalence of bacteremia caused by several clinically significant Streptococcus species (S. pyogenes, S. agalactiae, S. pneumoniae, S. dysgalactiae/equisimilis, the S. anginosus group (S. anginosus, S. constellatus, S. intermedius), and Enterococcus species (E. faecium and E. faecalis) over a 5 year period (2017-2022). Bacteria isolated from blood culture bottles were identified by MALDI-TOF mass spectrometry (VITEK® MS). Data were obtained from a Laboratory Results Repository in Epic Beaker to include these organisms, isolated in blood cultures (BCs), patient gender, patient age, and the collection date. The data were then consolidated to yield one unique organism per patient per episode. The prevalence of organisms as a percent of the total positive BCs for the overall time period and for each year was determined. Species from the Enterococcus genus were the two most prevalent organisms for each year except for 2017. E. faecalis was the most prevalent overall (57.4%, n = 534) and for each year except for 2020. Combining all analyzed organisms, S. agalactiae was the third most prevalent organism for each year except for 2017 when it was the second and 2020-2021 when it was the fourth. However, within the Streptococcus genus alone, S. agalactiae was the most prevalent (27.5%, n = 281). S. pneumoniae, demonstrating seasonality, was the second most prevalent from 2018-2019, however, it was outranked by S. dysgalactiae/equisimilis from 2020-2022 when it was the fourth and by the S. anginosus group in 2017 and 2020-2022. S. pyogenes was the fourth most prevalent organism in 2017 and the third most in 2018; however, it decreased in subsequent years and was surpassed by all other organisms. Stratified by decade of life, patients in their seventh decade of life (60-69 yr) accounted for the most positive BCs for every organism, except for E. faecalis, followed frequently by patients in their sixth (50-59 yr) and eighth (70-79 yr) decades of life. Patients in their first decade of life (0-9 yr) accounted for a preponderance of positive BCs for E. faecalis, S. agalactiae (highest prevalence <7 days of life), and S. pneumoniae. This study highlighted the relative abundance of bacteremia caused by Enterococcus species. Additionally, it demonstrated the importance of Streptococcus agalactiae bacteremia, especially in the first and seventh decades of life. Finally, this study showed the increasing prevalence of organisms within the Streptococcus anginosus group and Streptococcus dysgalactiae/equisimilis. This analysis demonstrated the dynamics of bacteremia and prevalence among several species within the Enteroccocus and Streptococcus genera.

172. Impact of a quality improvement re-training program on the blood culture volume, yield and contamination rates; experience from South India

Abstract Background Blood cultures help to detect causative agents in bacteremia and are important for targeted therapy. Adequate blood culture volume is considered as 8-10ml in each bottle and at least 2 aerobic and 2 anaerobic blood culture bottles are recommended. Inadequate blood culture fills are common and may affect yield. Figure 1 Methods The study was done in our healthcare facility-KIMSHEALTH, Trivandrum, India. Pre-intervention period was between May 2021 and June 2021; post-intervention was between May 2022 and June 2022. The intervention was through plan/do/study/act (PDSA) cycles and included multiple training sessions to the phlebotomy team regarding adequate fill volume which is 8-10 ml in each blood culture bottle. Training for maintaining asepsis during collection was reinforced. All blood culture samples received in the hospital microbiology laboratory during the above period were included in this study and compared between the pre-intervention and post-intervention period. Pediatric blood culture samples were excluded. Results Blood culture samples studied during pre and post intervention period were 1428 and 1716 respectively. In the pre-intervention phase adequate fill volume was noted in 30.81% bottles (figure 1), while in the post intervention adequate fill volume was noted in 68.06% bottles (p < 0.01). Blood culture contamination rate was 3.01% in the pre-intervention period which improved to 2% in the post-intervention period and the difference was significant (p< 0.01). Blood culture yield of a pathogenic organism did not show significant difference after the intervention (11.2% in pre-intervention group Vs 11.45% in post intervention group). Conclusion In this study, an improvement was noted in the blood culture fills by 38% and contamination rate reduced by 1%. Though there was no significant increase in blood culture yield with intervention, the reduction in contamination was noted which will reduce unnecessary antibiotic initiation. Disclosures All Authors: No reported disclosures

866. A new protocol for bacterial identification and carbapenemases by MALDI-TOF and lateral flow assay directly from positive blood culture: MALDI-FAST

Abstract Background Infectious diseases are a global public health problem, accounting for more than 20% of the mortality burden. Klebsiella pneumoniae and Pseudomonas aeruginosa caused more than 1.3 million deaths globally in 2019. Antimicrobial resistance (AMR) is a major factor in this mortality. Rapid molecular test for the detection of the blaKPC gene improves treatment time and mortality in patients with bacteremia caused by carbapenem-resistant Enterobacterales, however, the use of molecular biology techniques may not be optimal in multiple resourced care settings limited. Our goal is to perform rapid identification of Gram-negative bacilli and detection of carbapenemases directly from blood cultures using the combination of mass spectrometry (MALDI-TOF) and the lateral flow immunochromatography test.4 Methods We analyzed 97 bottles of positive blood cultures detected by the BACT/Alert 3D system (BioMérieux®). Our new method (MALDI-FAST) uses 0.5ml of blood obtained from the positive blood culture bottle for Gram-negative bacilli, from which a pellet is obtained by rapid centrifugation in 3 minutes. This material is processed both for bacterial identification by MALDI-TOF mass spectrophotometry (Bruker®), and rapid detection of carbapenemases by NG Test Carba 5 lateral flow immunochromatography (NG Biotech®). The results obtained were compared with the gold standard RT-PCR FilmArray Panel BCID 2.0 (BioMérieux®) Results Of the 97 blood culture bottles, 94/97 (96.9%) were correctly identified to the species level and 3/97 (3.1%) were polymicrobial blood cultures. Klebsiella pneumoniae was detected in 39 samples, E. coli in 24, and 34 other microorganisms including non-fermenting bacteria. Excellent concordance (kappa index 1,000) was achieved in 31/97 blood cultures (31.9%) that presented carbapenemases, 18/31 KPC (18.6%) and 13/31 with KPC and NDM coproduction (13.4%). 66/97(68.15%) bottles did not present carbapenemase. Conclusion Our protocol presents very good results for bacterial identification by mass spectrometry and carbapenemase detection by lateral flow immunoassay in a few minutes directly from the positive blood culture, becoming a fast and cost-effective tool to contribute to patient management. Disclosures All Authors: No reported disclosures

584. Microbiological Outcomes of Culture-Negative Blood Specimens Using 16s rRNA Broad-Range PCR Sequencing: a Retrospective Study in a Canadian Province from 2018 to 2022

Abstract Background Broad-range bacterial PCR sequencing (BRBPS) has emerged as a novel tool to detect fastidious organisms. While its utility has been characterized in different specimen types, its role in culture-negative blood specimens remains poorly understood. Methods We reviewed all clinical specimens sent for culture-negative blood BRBPS (blood, serum and blood culture bottles) to the Laboratoire de santé publique du Québec, the reference laboratory for a large Canadian province, from May 2018 to November 2022. Sanger sequencing of the amplified 16s rRNA gene was performed in all PCR-positive specimens. Data were extracted from the laboratory information system, and the analysis was restricted to the first specimen per patient. Microbiological outcomes were categorized as interpretable sequence, uninterpretable sequence, or negative PCR result. Interpretable sequences were identified and then classified based on the National Healthcare Safety Network database (NHSN; Table 1) and microbiological characteristics.Table 1.Definitions of National Health Safety Network (NHSN) Classification and Examples Results A total of 1199 blood specimens were analyzed using BRBPS from 852 unique patients. Of these, there was no PCR amplification in 152, amplification with uninterpretable sequences in 445 and an interpretable sequence in 255 specimens (Figure 1). Blood specimens received at room temperature, in blood culture bottles, or with positive gram stain were more likely to yield interpretable sequences (Table 2). We identified 174 patients with BRBPS results suggestive of organisms associated with mucosal barrier injury (n=89) or possible pathogens (n=85), summarized in Figure 2. In contrast, 75 patients had results suggestive of contamination from common commensal organisms (n=44) or taxa not in the NSHN database (n=31).Figure 1.Flowchart of the analysis from primary specimens to those specimens with successful amplification of 16s rRNA Classification of interpretable sequences using the National Healthcare Safety Network database classification of microorganisms.Table 2.Characteristics of BRBPS of the 16s rRNA on Culture-Negative Blood SpecimensFigure 2.Tree Map of Mucosal Barrier Injury Organisms and Possible Pathogens by Genera Mucosal barrier injury (A) and possible pathogens (B) are categorized based on the National Healthcare Safety Network database. Microorganisms are colour classified based on microbiological characteristics. Conclusion Our findings demonstrate the potential utility of BRBPS in blood specimens from culture-negative patients, particularly infectious syndromes caused by fastidious gram-negative bacteria associated with animal or arthropod exposures or anaerobic bacteria. However, the frequent recovery of commensal and environmental organisms argues for careful and judicious use. Additional technical optimization is likely required to improve diagnostic yield, particularly with mixed sequences. Disclosures Matthew Cheng, MD, Amplyx Pharmaceuticals: Grant/Research Support|AstraZeneca: Advisor/Consultant|AstraZeneca: Honoraria|Cidara Therapeutics: Grant/Research Support|GEn1E lifesciences: Advisor/Consultant|GEn1E lifesciences: Stocks/Bonds|Kanvas Biosciences, Inc.: Board Member|Kanvas Biosciences, Inc.: Pending patents|Kanvas Biosciences, Inc.: Ownership Interest|Merck: Honoraria|nomic bio: Advisor/Consultant|nomic bio: Stocks/Bonds|Pfizer: Honoraria|Scynexis Inc.: Grant/Research Support|Takeda: Advisor/Consultant|Takeda: Honoraria

254. Genomic diversity of Gram-negative Bacilli from Bloodstream Infections in Hospitalized Children

Abstract Background Gram-negative bloodstream infection (BSI) in hospitalized children is associated with significant morbidity and mortality. It is unclear whether bacterial clonality of isolates during BSI in a unique patient is associated with clinical characteristics such as immunocompromise. We hypothesized that genomic diversity of BSI isolates would be higher in immunocompromised patients due to mucosal barrier injury and therefore larger translocation bottleneck. Methods We prospectively enrolled patients with a central venous catheter who were hospitalized at Boston Children’s Hospital and had a positive blood culture that grew E. coli, Klebsiella spp., or Pseudomonas aeruginosa. An aliquot from the blood culture bottle was plated on agar, and at least 24 colonies were picked randomly and subjected to whole-genome sequencing (WGS). Patient-specific reference genomes were constructed using long-read sequencing of at least 1 isolate on the PacBio platform. All isolates were sequenced using Illumina (MiSeq or NextSeq). Single nucleotide variant (SNV) calls were made using the WideVariant pipeline (github). Clinical characteristics were obtained retrospectively from the electronic medical record. We defined immunocompromise as neutropenia (ANC< 500) on the day of BSI or prior solid organ or stem cell transplant. The proportion of BSI episodes with clonal blood isolates (defined as 0 SNV) was compared between immunocompromised and non-immunocompromised patients using Fisher’s exact test. Results We enrolled 34 patients (median age 2.33 years, IQR 0.8-3.8 years), 25 having BSI from Enterobacterales (11 E. coli, 14 Klebsiella spp.) and 9 from Pseudomonas aeruginosa. Immunocompromised patients had a significantly higher proportion of Enterobacterales BSI episodes with clonal isolates compared with non-immunocompromised patients [13/18 (72%) vs. 1/7 (14%) respectively, P=0.021). This was not seen with Pseudomonas BSI, which had clonal isolates in 3/5 (60%) vs. 2/4 (50%) respectively (P=1). Conclusion Contrary to our hypothesis, immunocompromised patients were more likely to have clonal Enterobacterales BSI isolates compared with non-immunocompromised patients, perhaps due to lower host pressures for bacterial population diversification in immunocompromised patients. Disclosures Arolyn Conwill, PhD, Day Zero Diagnostics: current employee|Day Zero Diagnostics: Stocks/Bonds

570. Impact of a Blood Culture Direct Identification Procedure on Time to Identification for Gram-Negative Organisms and Antimicrobial Management in Bloodstream Infections

Abstract Background Multiplex polymerase chain reaction (PCR) and microarray diagnostic methods for rapid identification (ID) in Gram-negative bloodstream infections (GNBSI) remain unavailable in many healthcare facilities. Use of other methods such as matrix-associated laser desorption/ionization time-of-flight (MALDI-TOF) along with rapid sample preparation from positive blood cultures, may decrease time to ID and targeted antimicrobial therapy in BSI. This study compares time to ID and final susceptibilities of Gram-negative bacteria (GNB) in positive blood cultures using a rapid MALDI-TOF direct ID process versus conventional culture methods, as well as impact on antimicrobial therapy in GNBSI. Methods This retrospective cohort included patients ≥18 years of age who had a positive blood culture with a GNB from January 1 through December 31, 2022, at a hospital serviced by the microbiology lab at Banner University Medical Center Phoenix (conventional ID) or Banner University Medical Center Tucson (direct ID). Direct ID consisted of using MALDI-TOF for immediate ID of a centrifuged sample from a GNB-positive blood culture bottle. The primary outcome was time to GNB ID between the two groups. Secondary outcomes included time from positive blood culture to susceptibility reporting, definitive antibiotic regimen, and hospital discharge. Statistical analysis performed with Wilcoxon Rank-Sum testing for continuous data, and Chi square testing for nominal data. Results A total of 254 patients were evaluated, with 100 included in each group. Median time to bacterial ID in the direct group vs. conventional group was 6.1 hr vs 29.2 hr (P< 0.0001). No differences in secondary outcomes, including times to final susceptibility (54.0 hr vs 60.9 hr, P=0.73), definitive antibiotic regimen (49.5 hr vs 44.9 hr, P=0.42), and hospital discharge (132.5 hr vs. 124.4 hr, P=0.85) were noted, though this study may have been unable to detect differences in such outcomes due to variance in organism resistance patterns and clinical practice between facilities. Conclusion Direct MALDI-TOF ID significantly decreases time to organism identification in GNBSI compared with conventional methods. Utilization of direct ID plus antimicrobial stewardship interventions in GNBSI is an area of opportunity. Disclosures All Authors: No reported disclosures

587. Research and Development of Image Recognition AI to Estimate Bacterial Species using Gram Stain Findings in Aerobic and Anaerobic Blood Culture Bottle

Abstract Background Background In the highly fatal infectious disease of bacteremia, the ability to select antimicrobial agents at an earlier time is critical not only for early patient recovery, but also for reducing the development of resistant organisms. Gram staining of blood cultures is a useful test for early selection of antimicrobial agents, but it requires some skill in deciphering. Therefore, we developed an image analysis system for Gram stain images of blood cultures and have verified whether it is possible to estimate the bacterial species to facilitate the initial selection of antimicrobial agents, regardless of the level of proficiency. Methods Method Slides and bacterial species-identification information from an anonymized Gram stain registry at two medical institutions, National Center for Global health and Medicine (NCGM) and Kobe University Hospital (KUH), were used for the study. 1113 cases of aerobic bottles and 1060 cases of anaerobic bottles were included. Mock-specimens were used for the rare bacteria. A total of 23,947 images were generated by capturing the observation field of view of an optical microscope with a smartphone. Table 1 shows the bacterial classification of aerobic bottles and Table 2 shows the bacterial classification of anaerobic bottles. The data were divided into training data and test data at a ratio of 8 to 2 for each category.Table 1.A total of 16 categories of bacteria were used for classification of aerobic bottlesTable 2.A total of 16 categories of bacteria were used for classification of anaerobic bottles Results The macro-average recall (sensitivity) and accuracy of the test data were 64% and 82% for aerobic bottles and 68% and 86% for anaerobic bottles, respectively. The results showed the possibility of classifying the performing bacterial species with an accuracy of over 70% using only Gram stained images via image recognition AI. For aerobic bottles in particular, the seven categories of GNR, GNC, GPR, GPC, yeast, No organism, and multiple bacteria are predicted to have 97% accuracy, and 90% macro average recall. Conclusion The research has shown that it is possible to classify bacterial species to a certain extent only by observing the Gram stain images. Our goal is to narrow down and focus more on the clinically-meaningful bacterial species, and to improve the accuracy of our classification. Also, we are planning to make comparisons with specialists in the future. Disclosures Kei Yamamoto, MD, Canon medical systems: Grant/Research Support|CarbGeM: Grant/Research Support|CarbGeM: 7090302|Fujirebio: Grant/Research Support|Sanyo Chemical Industries: Grant/Research Support|VisGene: Grant/Research Support Goh Ohji, MD, PhD, DTMH, CarbGeM: Advisor/Consultant

591. Positivity of Blood Culture on Automated Incubation System After 72 Hours and Clinical Significance from the Large United States Tertiary Care Center

Abstract Background Hospitals commonly use automated blood culture incubation systems that provide continuous monitoring for routine blood cultures. Detecting microorganisms early on can help optimize the utilization of antibiotics (ABx) and enable clinicians to de-escalate or discontinue ABx as necessary, making it an important aspect of antimicrobial stewardship. The BD BACTEC Fx, an automated system for blood culture incubation, holds blood culture bottles until growth is demonstrated or for five days unless an extended incubation period is requested by the infectious disease physician. We conducted a clinical evaluation of the significance of positive blood cultures after 72 hours of incubation time. Methods After receiving approval from the institutional review board (IRB), we obtained positive blood cultures from July 2017 to June 2020, which we then stratified based on positivity from day one to day five. To evaluate clinical significance, we retrospectively reviewed charts for positive blood culture results on day four and day five. An Infectious Diseases subspecialty team determined the clinical significance of each case. Results During the time frame of July 2017 to June 2020, there were 120,320 blood cultures taken. Out of these, 7,558 were determined to be positive, with 76 being positive on day 4 and 22 being positive on day 5. Upon further inspection of patients with positive blood cultures, it was discovered that repeat blood cultures continued to be positive due to either untreated sources or a high burden of bacteremia. It was also found that bottles containing fungus, particularly candida glabrata and candida albicans, tested positive on day 4 requiring treatment. Table 1 and Table 2 contain more detailed results. Blood cultures positive on day 4 Blood cultures positive on day 4 and clinical significance Blood cultures positive on day 5 Blood cultures positive on day 5 and clinical significance Conclusion In our study we have found that not all positive blood cultures at 72 hours translate into clinical scenarios requiring antibiotic therapy. In fact, prolonged antimicrobial treatment in such cases may lead to unnecessary exposure to antibiotics and increased risk of antibiotic resistance. It is important to consider the full context of clinical and laboratory findings when interpreting blood culture results, as well as any potential sources of contamination. Disclosures All Authors: No reported disclosures

Clinical usefulness of anaerobic blood culture in pediatric patients with bacteremia

ObjectivesThe purpose of this study is to evaluate the usefulness of anaerobic blood culture in pediatric patients by comparing the detection rate and distribution of bacteria between aerobic and anaerobic blood culture bottles. MethodsA retrospective analysis was conducted on 11,664 blood cultures obtained from children under the age of 14 between January 2013 and June 2020. The positive rate of total, aerobic, and anaerobic blood culture, as well as the species distribution of each blood culture bottle, were investigated. ResultsThe positive rate of blood culture was 2.4 % (N = 281). Among them, 67 (23.8 %), 85 (30.3 %) and 129 (45.9 %) organisms were grown in only aerobic, only anaerobic, and both blood culture bottles, respectively. Gram-positive cocci were cultured on both, only aerobic, and only anaerobic blood culture bottles in proportions of 46.4 %, 23.4 %, and 30.2 %, respectively. Gram-negative bacilli were cultured on both, only aerobic, and only anaerobic blood culture bottles in proportions of 58.5 %, 12,3 %, and 29.2 %, respectively. Gram-positive bacilli grew best in aerobic bottle only. There were seven strains of obligate anaerobes. ConclusionBecause many facultative anaerobic bacteria are recognized primarily from anaerobic blood culture bottles, combining aerobic and anaerobic blood culture bottles might be beneficial in pediatric patients with suspected blood stream infection.

The Growth of Red Spinach (Amaranthus tricolor L.) After Application of Bean Sprouts Extract [Vigna radiata (L.) R. Wilczek] on Murashige and Skoog Medium In Vitro

Red spinach (Amaranthus tricolor L.) is a commercially valuable vegetable known for its high nutritional content and immune-boosting properties, making it popular among the Indonesian population. However, red spinach cultivation in Indonesia is still relatively low and inconsistent, necessitating efforts to enhance its cultivation. One potential approach is through in vitro culture techniques. This study aimed to investigate the impact of applying mung bean sprout [Vigna radiata (L.) R. Wilczek] extract on Murashige and Skoog medium, focusing on identifying the most effective concentration for in vitro growth of red spinach explants. The experimental design employed a Completely Randomized Design (CRD) with five concentration levels: 0%, 5%, 10%, 15%, and 20%. Each concentration was replicated five times, with each replication consisting of five red spinach seeds in individual culture bottles. Data analysis involved Levene's test, one-way ANOVA, and Tukey's Honestly Significant Difference (HSD) test at a significance level of 5%. The findings revealed that the application of mung bean sprout extract significantly influenced the height of plantlets, leaf count, root length, fresh weight, and soluble carbohydrate content of red spinach. The most effective concentration for promoting red spinach explant growth was determined to be 5%.

Abstract 16120: Efficacy of an Electronic Medical Record Alert System in Identifying Cardiac Implantable Electronic Device Infection

Introduction: Cardiac Implantable Electronic Device infection (CIED-I) is common, morbid, and frequently under recognized. Electronic Medical Record (EMR) based alerts have been proposed as a solution to improve detection of CIED-I. Hypothesis: Development of a real-time EMR algorithm to identify CIED-I can improve recognition of patients with CIED-I. Methods: An EMR (Epic, Verona, WI) alert system to identify inpatients with CIED-I was developed based on the presence of CIED and positive blood cultures. The presence of CIED was determined using patient problem list, structured data elements describing device implantation, and prior device interrogation. Alerts were generated each time a patient with CIED had a positive blood culture. We examined patients admitted between January 2020 - March 2023. Identified patients were adjudicated manually to confirm: (1) the presence of CIED and (2) true bacteremia versus contaminant based on patient and microbiological characteristics. Results: The algorithm generated 255 alerts, corresponding to 100 unique patients over 142 hospitalizations. Of these alerts, 213 appropriately identified 88 unique patients with positive blood cultures and CIEDs, resulting in an alert specificity of 84% and patient specificity of 88%. The remaining 42 (16.6%) alerts occurred in 10 patients who no longer had CIED due to prior CIED extraction (6 at the time of heart transplant and 4 with extraction without reimplantation) as well as 2 patients with erroneous blood culture identification (one positive syphilis antibody test and one lab documentation error). In patients with appropriate alerts, 27 patients had 4/4 positive blood culture bottles, 5 patients had 3/4, 10 patients had 2/4, 41 patients had 1/4, 2 patients had 2/2, and 1 patient had 1/2. The positive predictive value of the algorithm to identify true bacteremia was 0.65 (138/213). Conclusions: The algorithm has high specificity to identify patients with possible CIED infection. Improving the accuracy of device detection, by incorporating radiology imaging or history of extraction, could further improve specificity. Positive predictive value and alert fatigue could be improved by stratifying alerts by blood culture species and total number of positive blood cultures.

Suitability Analysis of Gram Staining with Blood Culture in Bacteremia

Bacteremia is a serious bloodstream infection, requiring blood culture as the gold standard for definitive diagnosis and rational therapy, but it is time-consuming. The Gram stain should be considered as an alternative test, as it is easier and faster to determine empirical antibiotic therapy in order to minimize the use of broad-spectrum antibiotics. This study aimed to analyze the suitability of Gram staining results with blood cultures in bacteremia. Cross-sectional study design from August to September 2022 at Dr. Wahidin Sudirohusodo Hospital and Labuan Baji Hospital, Makassar. The study sample used specimens from automatic positive blood culture bottles of new bacteremia patients. Gram staining and sub-culture were performed to determine the type of Gram-positive or negative bacteria. Appropriate statistical analysis was used to compare the two methods. A total of 78 research samples were obtained. The results of subculture vs. Gram staining showed Gram-positive bacteria in 45 vs. 42 samples and Gram-negative bacteria in 33 vs. 36 samples, respectively. A comparative test using the Wilcoxon test showed no significant difference for the 2 tests, p-value = 0.257 (p > 0.05). The results of the Gram diagnostic test on culture showed high sensitivity and specificity, respectively: 88.9%, and 93.9% for Gram-positive bacteria, 93.9% and 88.9% for Gram-negative bacteria. Positive Predictive Value (PPV) and Negative Predictive Value (NPV) were 95.32% and 95.32% for Gram-positive, 86.11%, and 95.23 % for Gram-negative bacteria, respectively. There is a suitability between Gram stain and automatic blood culture results with high diagnostic value. Gram staining is expected to be a guide for selecting empirical therapy based on Gram's classification until the AST test results come out.

Optimizing Blood Culture Collection Volumes.

Infection in an immunocompromised person can be a life-threatening emergency. Collection of blood culture specimens is an important method for detecting organisms when infection is suspected. One aspect of proper blood culture collection is obtaining an accurate blood volume in the sample in accordance with the blood culture bottle manufacturer's recommendation. Underfilling the culture bottle can lead to false-negative results, while overfilling it can lead to false-positive results. At our institution, the Department of Laboratory Medicine (DLM) routinely monitors blood culture bottle volumes and notifies the nursing department of underfill/overfill events, which the department then reviews. Over several years, the DLM and the nursing department noted an increase in these events. A clinical nurse specialist and three staff nurses in the oncology/critical care services area partnered with the DLM to determine why. Upon investigation, two key issues-imprecise weighing of bottles and staff misunderstanding of the proper blood culture collection technique-were discovered. In response, the nursing standard of practice and guidance on the DLM webpage were updated and nursing education was performed. As a result, underfill/overfill events decreased by 71% in a little over a year.

Evaluation of a Modified Protocol for the SepsiPrep Kit for Direct Identification and Antimicrobial Susceptibility Testing From Positive Blood Culture Using BACTEC Plus and BacT/Alert Blood Culture Bottles

Evaluation of a Modified Protocol for the SepsiPrep Kit for Direct Identification and Antimicrobial Susceptibility Testing From Positive Blood Culture Using BACTEC Plus and BacT/Alert Blood Culture Bottles

Antimicrobial Susceptibility Patterns of Gram-negative Bacteria, Gram-positive Bacteria and Fungi Species Isolated from Blood Culture Bottles in Yaounde, Cameroon

Antimicrobial Susceptibility Patterns of Gram-negative Bacteria, Gram-positive Bacteria and Fungi Species Isolated from Blood Culture Bottles in Yaounde, Cameroon

Evaluation of Different Blood Culture Bottles for the Diagnosis of Bloodstream Infections in Patients with HIV.

Bloodstream infection (BSI) is a significant factor contributing to hospitalization and high mortality rates among human immunodeficiency virus(HIV)-positive patients. Therefore, the timely detection of this condition is of utmost importance. Blood culture is considered the gold standard for diagnosing BSIs. Currently, BD BACTEC™ Plus Aerobic/F culture bottles and the BD BACTEC™ Myco/F Lytic culture bottles can be used for blood culture. This study aimed to evaluate the efficacy of two different types of culture bottles in diagnosing BSIs in patients with HIV. A retrospective analysis was conducted on HIV-positive patients hospitalized in the Infection Department of Wenzhou Central Hospital between July 2019 and October 2021. A total of 246 pairs of blood samples were included, consisting of an aerobic culture vial and a Myco/F culture vial. Blood culture results and clinical diagnosis were utilized to identify the presence of BSI. Out of 246 cases, 84 cases had positive blood cultures. Fungal BSIs, particularly Talaromycesmarneffei BSIs, were the most prevalent among patients with HIV. The positive rate of Myco/F culture bottles (89.29%) was significantly higher compared with aerobic culture bottles (69.05%; P = 0.001). In the diagnosis of fungal BSIs, the positive rate of Myco/F culture bottles was 88.57%, which was significantly higher than that of aerobic culture bottles (72.86%; P = 0.018). The Myco/F culture bottle has more advantages in diagnosing Talaromyces marneffei BSIs (P=0.028).In addition, mycobacteria were exclusively detected in Myco/F culture bottles. Fungal BSIs are the predominant type of infections in HIV-positive patients. Myco/F culture bottles exhibit noteworthy attributes of high positive rate in diagnosing HIV combined with BSI. These advantages are conducive to obtaining accurate culture results and minimizing missed diagnoses.

Electronic nose versus VITEK 2 system for the rapid diagnosis of bloodstream infections

Infectious diseases that spread through the bloodstream, known as bloodstream infections (BSIs), are a major global health problem. Positive outcomes for patients with sepsis are typically the result of prompt treatment started after an early diagnosis of BSIs. In this study, we evaluated the capabilities of a portable electronic nose (E-Nose) to detect BSIs with two commonly isolated Gram-negative bacterial species, E. coli and K. pneumonia. One hundred and five blood samples were randomly collected for blood culture examinations using BACTEC and VITEK 2 system, and headspace analysis by an E-Nose from June to December 2021. Classification accuracy of E. coli, K. pneumonia, and negative controls was measured using principal component analysis, area under the receiver operating characteristic curve, sensitivity, and specificity analysis. After incubation for 24 h, cluster plots generated using principal component analysis demonstrated that E-Nose could accurately diagnose the presence of E. coli and K. pneumonia in BACTEC blood culture bottles with a sensitivity and specificity of 100% in just 120 s. The E-Nose method has been shown to be an immediate, precise, and cost-effective alternative to automated blood culture BACTEC and VITEK 2 systems for the fast detection of the causative bacterial pathogens of BSIs in clinical practice. Thus, patients with such Gram-negative bacteremia can have guided empirical antimicrobial therapy on the same day of BSIs diagnosis, which can be lifesaving.

Evaluation of prolonged incubation time of 16-20 h with the EUCAST rapid antimicrobial susceptibility disc diffusion testing method.

Antimicrobial resistance rates are continuously increasing, driving the need for rapid antimicrobial susceptibility testing (RAST) results, especially in the treatment of bloodstream infections. The EUCAST RAST method performed directly from positive blood cultures with incubation times from 4 to 8 h was developed in 2018 and is now used in many laboratories. To increase the practicality of the method, an extended incubation time of 16 and 20 h was evaluated in this study. Blood culture bottles were spiked with clinical isolates (n = 325) of the seven most important sepsis pathogens. The EUCAST RAST method was performed, extending the incubation time to 16 and 20 h. Broth microdilution (BMD) was used as a reference, except for screening tests where standard disc diffusion or presence of resistance genes was used. Inhibition zones were possible to read for all species-agent combinations. For 16 and 20 h, the MIC zone diameter correlations were sufficiently similar to allow establishment of common breakpoints for the time interval of 16-20 h. The proportion of isolates in the area of technical uncertainty was, on average, 6% for all species and the number of errors were low, with <1% false-resistant and <0.5% false-susceptible results. This study shows that, for EUCAST RAST, prolonging the recommended incubation to 16-20 h is possible and can be used as a complement when the intended shorter incubation is not possible to achieve. The introduction of the prolonged incubation will increase the usefulness of the EUCAST RAST method in clinical laboratories with limited opening hours.

A calibration-free, non-invasive, and accurate total viable count detection method based on tunable diode laser absorption spectroscopy combined with most probable number counting

Total viable count (TVC), as an important indicator in the microbiological detection. A calibration-free, non-invasive, and accurate TVC detection method was developed using the most probable number (MPN) method and tunable diode laser absorption spectroscopy (TDLAS). In the experiment, a tunable distributed feedback (DFB) laser with a center wavelength of 4989.97 cm−1 was used to measure CO2 emitted from the microorganisms in a sealed culture bottle. Then, the thresholds of negative and positive culture bottles in the MPN-TDLAS method were established by the features of the Staphylococcus aureus (S. aureus) growth curve. The experimental results revealed that the MPN-TDLAS method has a good correlation (R2 = 0.99) with the TVC of the ISO:4833:2013 standard plate counting method, and the result of the quality control (QC) sample was satisfactory (Z-score was less than 2), which demonstrated that this method is well-suited for food microbiology testing applications.