Diagnosis Of Bloodstream Infections Research Articles

Application of next-generation sequencing on diagnosis of bloodstream infection caused by Mycoplasma hominis in a patient with ANCA-associated vasculitis

BackgroundMycoplasma hominis is one of the main opportunistic pathogenic mycoplasmas in humans which has a major impact on patients with bloodstream infections. Because it is difficult to detect or isolate, rapid and accurate diagnosis using improved methods is essential and still challenging for patients with bloodstream infection.Case presentationIn this case, we reported the application of next -generation sequencing for the diagnosis of bloodstream infection caused by Mycoplasma hominis in a patient with Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. After 9 days of combined treatment with levofloxacin, polymyxin B and meropenem, the patient’s condition was gradually controlled and he was discharged without further complications. During the three-month outpatient follow-up, no recurrence of symptoms or clinical signs was reported.ConclusionsThis successful application of next generation sequencing assisted the rapid diagnosis of Mycoplasma hominis bloodstream infection, provided a new perspective in the clinical approach and highlighted the potential of this technique in rapid etiological diagnosis.

Incidence, Risk Factors and Outcome of Bloodstream Infections in Patients After Hematopoietic Stem-Cell Transplantation: A Single Center Study.

The bloodstream infections (BSIs) are among the most common infectious complications after hematopoietic stem-cell transplantation (HSCT), often associated with high mortality rates. The aim of this study was to evaluate the incidence, risk factors and outcome of BSIs in HSCT recipients from the Transplantation Center of the University Hospital in Varna, Bulgaria during the period January 2019-December 2021. The role of patient- and transplantation-related variables was studied as potential risk factors for BSIs and survival after HSCT. Seventy-four patients were included in the study. The cumulative incidence of BSIs was 35%. The mean period of BSI onset after HSCT was 8days. The Gram-positive bacteria were more commonly isolated as causative agents (52.3%). The mortality rate 30days after the diagnosis of BSI was 23%. Fecal colonization with multidrug-resistant (MDR) bacteria (p = 0.005) and pre-transplant BSI (p = 0.05) were associated with significantly increased risk for post-HSCT BSIs. The overall 4-month survival was 86.5%. A statistical significance was found between the type of the underlying disease (acute leukemia and lymphoma, p = 0.043), previous HSCT (p = 0.001) and 4-month survival. This study confirms that the fecal colonization with MDR bacteria before transplantation and pre-transplant BSIs are independent risk factors for the occurrence of BSI in the early period after HSCT. Pre- and posttransplant monitoring of the patient fecal colonization status with MDR organisms, could contribute considerably to the prevention and successful management of the infectious complications in patients after HSCT.

Electrochemical label-free pathogen identification for bloodstream infections diagnosis: Towards a machine learning based smart blood culture bottle

Bloodstream infections are a growing public health concern. Current pathogen identification systems are based on complex and expensive devices, intended for use in centralized laboratories. Subsequent identification requires harmful chemical reagents, specialized personnel and time. Here we describe a new approach for rapid and decentralized diagnosis of positive blood cultures using electrochemical sensors. By implementing a multi-material potentiometric platform in a blood culture bottle, we have developed a portable system for pathogen identification of Gram and of genus. Bacterial growth in human blood generates a specific label-free multiplex electrochemical fingerprint according to the detected species. Analysis of these fingerprints using homemade machine learning algorithms allow for rapid identification of the pathogen after detection (14 species and 9 genus) (GRAM= 99 % accuracy 5.75 h after detection, GENUS= 85 % accuracy 7.8 h after positivity) without further handling of the contaminated sample.

Factors impacting the pre-analytical quality of blood cultures-Analysis at a tertiary medical center.

Blood cultures (BC) are critical for the diagnosis of bloodstream infections, pathogen identification, and resistance testing. Guidelines recommend a blood volume of 8-10 mL per bottle as lower volumes result in decreased sensitivity. We aimed to evaluate factors for non-adherence to recommended volumes and assess the effects on diagnostic performance. From February to April 2020, we measured collected blood volumes by weighing all BC containers from inpatient samples at the University Hospital Basel. Information on BC volumes was merged with clinical and microbiological data, as well as nursing staff schedules. We analyzed factors associated with (i) BC sampling volume, (ii) reaching recommended volumes (≥8 mL), (iii) BC positivity, and (iv) time to positivity using linear and generalized linear mixed effect models. We evaluated a total of 4'118 BC bottles collected from 686 patients. A total of 1'495 (36.3%) of all bottles contained the recommended filling volume of ≥8 mL. Using a central venous and arterial catheter for drawing blood resulted in an increase of filling volume by 0.26 mL (95% CI 0.10, 0.41) and 0.50 mL (95% CI 0.31, 0.69) compared to peripheral venipuncture, respectively. Each additional nursing staff working at the time of blood drawing was associated with 6% higher odds of achieving the recommended filling volume. We found no significant correlation between the filling volume and the positivity rate. Our results indicate critical pre-analytical quality markers linked to BC collection procedures to reach recommended collection volumes. No significant impact on the positivity rate was found.

Metagenomic next-generation sequencing of plasma for the identification of bloodstream infectious pathogens in severe aplastic anemia

Objective: To analyze the diagnostic value of cell-free plasma metagenomic next-generation sequencing (mNGS) pathogen identification for severe aplastic anemia (SAA) bloodstream infection. Methods: From February 2021 to February 2022, mNGS and conventional detection methods (blood culture, etc.) were used to detect 33 samples from 29 consecutive AA patients admitted to the Anemia Diagnosis and Treatment Center of the Hematology Hospital of the Chinese Academy of Medical Sciences to assess the diagnostic consistency of mNGS and conventional detection, as well as the impact on clinical treatment benefits and clinical accuracy. Results: ①Among the 33 samples evaluated by mNGS and conventional detection methods, 25 cases (75.76%) carried potential pathogenic microorganisms. A total of 72 pathogenic microorganisms were identified from all cases, of which 65 (90.28%) were detected only by mNGS. ②All 33 cases were evaluated for diagnostic consistency, of which 2 cases (6.06%) were Composite, 18 cases (54.55%) were mNGS only, 2 cases (6.06%) were Conventional method only, 1 case (3.03%) was both common compliances (mNGS/Conventional testing) , and 10 cases (30.3%) were completely non-conforming (None) . ③All 33 cases were evaluated for clinical treatment benefit. Among them, 8 cases (24.24%) received Initiation of targeted treatment, 1 case (3.03%) received Treatment de-escalation, 13 cases (39.39%) received Confirmation, and the remaining 11 cases (33.33%) received No clinical benefit. ④ The sensitivity of 80.77%, specificity of 70.00%, positive predictive value of 63.64%, negative predictive value of 84.85%, positive likelihood ratio of 2.692, and negative likelihood ratio of 0.275 distinguished mNGS from conventional detection methods (21/12 vs 5/28, P<0.001) . Conclusion: mNGS can not only contribute to accurately diagnosing bloodstream infection in patients with aplastic anemia, but can also help to guide accurate anti-infection treatment, and the clinical accuracy is high.

A Comparative Study of Conventional and Automated Blood Culture System in Adult Patients

Introduction: Blood culture is considered as the gold standard for the diagnosis of bloodstream infection. Conventional blood culture system is less sensitive and takes longer duration for the detection of bloodstream infections whereas automated blood culture system is more sensitive and rapid in detecting causative organisms of bloodstream infections. This prospective study was undertaken to compare the automated blood culture system with the conventional blood culture system for the identification of microbial pathogens in bloodstream infections. Method: This prospective study was done in Department of Microbiology, Silchar Medical College &amp; Hospital, Silchar for a period of 7 months from November 2021 to May 2022. Blood samples from the patients were inoculated into BD BACTEC Plus Aerobic culture vials for automated blood culture system and Brain Heart Infusion broth for conventional blood culture system. Positive bottles flagged by the automated machine were isolated and identified by doing routine subcultures on Blood agar and MacConkey agar and necessary biochemical tests. The conventional blood culture bottles were processed as per standard protocols. Result: Out of 123 samples, 21(17.09%) showed culture positivity by automated blood culture method and 15(12.19%) showed culture positivity by conventional blood culture method. The most common isolate was Staphylococcus aureus followed by Escherichia coli in automated method whereas the most common isolate in conventional method was Staphylococcus aureus followed by Klebsiella pneumoniae. Conclusion: This study concluded that automated blood culture method is more sensitive than conventional method and detects the presence of microorganisms rapidly causing bloodstream infections. Keywords: Bloodstream infection, Automated blood culture, Conventional blood culture

IS PROCALCITONIN AN ACCURATE MARKER IN THE DIAGNOSIS OF ACINETOBACTER-INDUCED BACTEREMIA?

Nosocomial bloodstream infections are common in intensive care units, and a significant portion results in mortality. Procalcitonin is a biomarker used in the early diagnosis of bloodstream infections. Since different pathways release it, its level in the blood may differ in bloodstream infections caused by different agents. The present study was designed to demonstrate whether procalcitonin was an accurate marker in nosocomial bloodstream infections caused by Acinetobacter spp. The present study evaluated 214 bacteremia episodes of 145 patients diagnosed with nosocomial bloodstream infection. Nosocomial bloodstream infection agents were divided into four groups gram-positive bacteria, gram-negative bacteria, Acinetobacter spp., and Candida spp. At the time of diagnosis, procalcitonin, C-reactive protein, neutrophil/lymphocyte ratio, and leukocyte values were measured on the 3rd and 7th days. The mean procalcitonin value measured at the time of diagnosis was 11.7±21.8 ng/ml, the highest in the gram-negative bacteria group. The mean procalcitonin value in the gram-positive bacteria group was 2.8±6.44 ng/ml, 2.5±3.35 ng/ml in the Candida spp. group, and 3.5±12.1 ng/ml in the Acinetobacter spp. group. A significant difference was determined between the four groups regarding procalcitonin values. It was determined that the blood procalcitonin level at the time of diagnosis did not increase as expected in Acinetobacter spp.-induced nosocomial bloodstream infections. In this respect, caution should be exercised in the early diagnosis of nosocomial bloodstream infections.

The application of nanopore targeted sequencing in the diagnosis and antimicrobial treatment guidance of bloodstream infection of febrile neutropenia patients with hematologic disease.

Traditional microbiological methodology has limited sensitivity, detection range, and turnaround times in diagnosis of bloodstream infection in Febrile Neutropenia (FN) patients. A more rapid and sensitive detection technology is urgently needed. Here we used the newly developed Nanapore targeted sequencing (NTS) to diagnose the pathogens in blood samples. The diagnostic performance (sensitivity, specificity and turnaround time) of NTS detection of 202 blood samples from FN patients with hematologic disease was evaluated in comparison to blood culture and nested Polymerase Chain Reaction (PCR) followed by sanger sequence. The impact of NTS results on antibiotic treatment modification, the effectivity and mortality of the patients under the guidance of NTS results were assessed. The data showed that NTS had clinical sensitivity of 92.11%, clinical specificity of 78.41% compared with the blood culture and PCR combination. Importantly, the turnaround time for NTS was <24 h for all specimens, and the pre-report time within 6 h in emergency cases was possible in clinical practice. Among 118 NTS positive patients, 98.3% patients' antibiotic regimens were guided according to NTS results. There was no significant difference in effectivity and mortality rate between Antibiotic regimen switched according to NTS group and Antibiotic regimen covering pathogens detected by NTS group. Therefore, NTS could yield a higher sensitivity, specificity and shorter turnaround time for broad-spectrum pathogens identification in blood samples detection compared with traditional tests. It's also a good guidance in clinical targeted antibiotic treatment for FN patients with hematologic disease, thereby emerging as a promising technology for detecting infectious disease.

Evaluation of InTray Cassettes Directly from Blood Cultures for the Diagnosis of Sepsis in Clinical Bacteriology Laboratories as an Alternative to Classic Culture Media.

Culture media is fundamental in clinical bacteriology for the detection and isolation of bacterial pathogens. However, in-house media preparation could be challenging in low-resource settings. InTray® cassettes (Biomed Diagnostics) could be a valid alternative as they are compact, ready-to-use media preparations. In this study, we evaluate the use of two InTray media as a subculture alternative for the diagnosis of bloodstream infections: the InTray® Müller-Hinton (MH) chocolate and the InTray® Colorex™ Screen. The InTray MH chocolate was evaluated in 2 steps: firstly, using simulated positive blood cultures (reference evaluation study), and secondly, using positive blood cultures from a routine clinical laboratory (clinical evaluation study). The Colorex Screen was tested using simulated poly-microbial blood cultures. The sensitivity and specificity of the InTray MH chocolate were respectively 99.2% and 90% in the reference evaluation study and 97.1% and 88.2% in the clinical evaluation study. The time to detection (TTD) was ≤20 h in most positive blood cultures (99.8% and 97% in the two studies, respectively). The InTray® MH Chocolate agar showed good performance when used directly from clinical blood cultures for single bacterial infections. However, mixed flora is more challenging to interpret on this media than on Colorex™ Screen, even for an experienced microbiologist.

Role of rapid tests in diagnosis of bloodstream infections and their effect on promoting antibiotic stewardship among febrile neutropenic patients in Alexandria

Abstract Background Bloodstream infections (BSIs) in neutropenic patients significantly contribute to morbidity and mortality. The rapid identification and determination of antimicrobial susceptibility of pathogens causing BSIs can help in early initiation of targeted antimicrobial therapy and allow de-escalation of unnecessary empirical antimicrobials. Aim This study evaluated the rapidity and accuracy of gram-stained smear from blood culture bottles and direct VITEK 2 to identify and determine antimicrobial susceptibility of pathogens causing BSIs and assessed the effect of these tests on modification of empiric therapy. Patients and methods Blood cultures were collected from 100 febrile neutropenic patients from the Hematology Unit in Alexandria Main University Hospital. Gram-stained smears were prepared from blood culture bottles; blood from bottles with suggestive smears was directly inoculated into the VITEK 2 system, and results were compared with conventional methods. Results were instantly reported to clinicians. Empirical antimicrobials and their modification were recorded. Results BSI was detected in 30% of patients. Gram-negative bacteremia was predominant (24/30). Gram-stained smears showed complete accordance with conventional methods in 99 samples. VITEK 2 correctly identified all tested microorganisms, and the overall agreement in susceptibility testing was 100 and 95.2% for gram-positive and gram-negative bacteria, respectively. The effect of these rapid tests on empiric antimicrobial therapy was evident in 12 of 30 patients with documented BSIs (40%). Conclusion Gram-stained smear and direct VITEK 2 testing when integrated with instant reporting is a valid approach to guide targeted therapy in neutropenic patients in the context of extremely resistant pathogens.

The Value of Procalcitonin Combined with C-Reactive Protein Assay in the Early Clinical Diagnosis of Bloodstream Infection

The Value of Procalcitonin Combined with C-Reactive Protein Assay in the Early Clinical Diagnosis of Bloodstream Infection

Evaluation of the influence of the analytical characteristics of the microbiological blood study in bacteremia in a multidisciplinary hospital.

The culture method continues to be the "gold" standard for microbiological diagnosis of bloodstream infections. This is primarily due to the fact that the definition of the etiology of a generalized infectious process determines the etiotropic antibiotic therapy. To do this, it is necessary to conduct periodic microbiological monitoring of the prevailing microflora. To do this, in the present study, a retrospective analysis of the results of a microbiological blood test for sterility was performed in case of suspected bloodstream infections in a multidisciplinary hospital to assess the influence of analytical stage factors on the laboratory data obtained. Automatic hematological cultivators were used, identification was carried out based on the biochemical characteristics of microorganisms, as well as using time-of-flight mass spectrometry with matrix-activated laser desorption / ionization (MALDI-TOF MS). More than 10,000 research results were analyzed, the average microflora seeding rate was 15.1%. The analysis of the isolated microflora was carried out in 2 groups of positive results: at the beginning, the data obtained in the presence of growth in two vials at once were evaluated, then the positive results of blood cultures obtained in any one vial from a pair were studied. The predominance of gram-positive flora in the structure of microorganisms isolated from whole blood was revealed, the influence of cultivation conditions and the composition of thenutrient medium on the isolated flora was not found, however, a number of microorganisms, due to the specific characteristics of metabolism, were characterized by growth under strictly defined cultivation conditions. The presented study actualizes the need for constant microbiological monitoring in order to determine the prevailing hospital microflora, which can contribute to a timely response in order to limit the spread of highly virulent, aggressive, resistant strains of microorganisms leading to the development of generalized bloodstream infections.

Intrinsic values of procalcitonin in bacterial bloodstream infections in people aged 75 years and over: a retrospective study

ObjectiveTo evaluate PCT measurement in the diagnosis of bloodstream infection (BSI) in hospitalized patients aged 75+. MethodDescriptive, retrospective, monocentric study conducted in France, in patients with at least one blood culture and PCT and CRP measurements within the 24 hours before or after blood culture. ResultsThe mean PCT and CRP values for the 118 (15.2%) positive blood cultures were 18.90 ng/ml [95%CI: 0.007−334.7] and 153.93 mg/l [1−557], respectively. With a threshold of 0.3 ng/ml, PCT measurement had a sensitivity of 84%, a specificity of 53%, a PPV of 24%, and an NPV of 95%, making it possible to rule out BSI in 350 (45.1%) patients (α-risk=5%). ConclusionPCT measurement may eliminate BSI diagnosis more quickly than does blood culture reducing the inadequate and detrimental use of antibiotic therapy. A prospective study is required to validate its usefulness and confirm the cut-off value in geriatric populations.

Pcv-aCO2 and procalcitonin levels for the early diagnosis of bloodstream infections caused by gram-negative bacteria.

The central venous-to-arterial carbon dioxide difference (Pcv-aCO2) is a biomarker for tissue perfusion, but the diagnostic value of Pcv-aCO2 in bacteria bloodstream infections (BSI) caused by gram-negative (GN) bacteria remains unclear. This study evaluated the expression levels and diagnostic value of Pcv-aCO2 and procalcitonin (PCT) in the early stages of GN bacteria BSI. Patients with BSI admitted to the intensive care unit at Guangdong Provincial People's Hospital between August 2014 and August 2017 were enrolled. Pcv-aCO2 and PCT levels were evaluated in GN and gram-positive (GP) bacteria BSI patients. A total of 132 patients with BSI were enrolled. The Pcv-aCO2 (8.32 ± 3.59 vs 4.35 ± 2.24 mmHg p=0.001) and PCT (30.62 ± 34.51 vs 4.92 ± 6.13ng/ml p=0.001) levels were significantly higher in the GN group than in the GP group. In the diagnosis of GN bacteria BSI, the area under the receiver operating characteristic curve (AUROC) for Pcv-aCO2 was 0.823 (95% confidence interval (CI): 0.746-0.900). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 71.90%, 88.00%, 74.07% and 78.21%, respectively. The AUROC for PCT was 0.818 (95% CI: 0.745-0.890). The sensitivity, specificity, PPV and NPV were 57.90%, 94.67%, 71.93% and 74.67%, respectively. Pcv-aCO2 and PCT have similar and high diagnostic value for the early diagnosis of BSI caused by GN bacteria.

The Accelerate Pheno™ System-A New Tool in Microbiological Diagnostics of Bloodstream Infections: A Pilot Study from Poland.

The aim of this study was to evaluate the usefulness of the Accelerate Pheno™ system (APS) (Accelerate Diagnostics, Denver, CO, USA) for rapid laboratory diagnosis of bloodstream infections. The study included 45 positive blood samples obtained from patients hospitalized in University Hospital No. 1 in Bydgoszcz, Poland. In 40 (88.9%) blood samples, the APS was capable of identification of at least one microorganism at the genus or species level and in 38 (84.4%) of them additionally assessed antimicrobial susceptibility. The time of identification and the time to result of antimicrobial susceptibility ranged from 1:32 to 1:42 and 5:02 to 5:36 h, respectively. Six positive blood samples revealed a poly-microbial culture. In these cases, only one out of two or three microorganisms was detected by the APS, and the system assessed antimicrobial susceptibility only for them. For 78.6% positive blood samples, agreement on identification compared to mass spectrometry was found. For all but one sample, a 96-100% compliance of the resistance category was achieved when comparing the antimicrobial susceptibility testing results to conventional methods. Using the APS, the total time to report was reduced from 13:34 to even 63:47 h compared to the standard microbiological laboratory workflow. The APS is a very useful system, especially for the rapid assessment of antimicrobial susceptibility of bacteria directly from positive blood samples, offering the greatest potential for microbiology laboratories operating around the clock.

The Role of Metagenomics Next-Generation Sequencing (mNGS) in Early Diagnosis of Bloodstream Infection in Hematologic Patients with Febrile Neutropenia: A Multicenter Prospective Study

Background: Bloodstream infection (BSI) is a lethal complication in hematologic patients with febrile neutropenia (FN). The delayed diagnosis and intervention will lead to significant mortality. Unfortunately, the traditional golden standard diagnostic method using blood culture (BC) can only identify pathogens in 20-30% patients with BSI, and usually needs more than 48 hours. Therefore, novel methods with fast turnover, improved sensitivity and specificity are needed. Metagenomics next-generation sequencing (mNGS) shows promise as diagnostic testing for difficult and critical infectious diseases in immunodeficient hosts, but its significance in BSI of hematological patients remains unclear, and has not been evaluated in prospective study. Aims: To evaluate the ability of mNGS to identify infectious etiologies in FN patients with BSI. Method: This study was prospective performed in four Chinese hematologic centers since October 2021. For patients≥15 years with hematologic diseases, patients were screened at the onset of neutropenia. At the onset of FN, Peripheral blood specimens were collected per subject for simultaneous BC and mNGS (separate sequencing for plasma and blood cells). All patients will be followed for 14 days, or until death before 14 days. The intervention was per the attending physician. The primary endpoints of this study is the sensitivity and specificity of mNGS. Thepositive agreement was defined as mNGS identified at least one same pathogen as initial BC. The negative agreement was defined as both mNGS and BC were negative. And the adjudication of the result of BC, mNGS, and clinical diagnosis was evaluated by 4 independent specialists in hematology. Clinical adjudication categorized mNGS results as: Definite, mNGS identified at least one pathogen also found by BC or SMT with in 7 days; Probable, mNGS result was concordant with a clinical diagnosis of BSI in FN; Possible, mNGS result was consistent with BSI but not considered a common cause of FN; Unlikely, mNGS result was not a plausible cause of BSI in FN. This study was registered on ClinicalTrials.gov ID: NCT05149547. This is an interim analysis of 134 patients enrolled in this multicenter, prospective observational study. Results: Te basic information of the patients was summarized in table 1. Clinical adjudication categorized mNGS results as: Definite (N=24); Probable (N=21); Possible (N=7); Unlikely (N=49). Definite, probable and possible cases were regarded as true positives. The positive percent agreement (PPA) and negative percent agreement (NPA) with BC were 80.0% (20/25) and 25.7% (28/109) respectively; 44% of mNGS results were polymicrobial (except viruses). According to the clinical adjudication, mNGS sensitivity and specificity were 94.6% (52/55) and 38.0% (30/79) respectively (table 2 and table 3). Compared with BC, the reporting time of mNGS was significant shorter (24.8±4.0 vs. 72.3±21.2 h, p < 0.05). Conclusions: Compared with conventional BC, mNGS might provide an early and rapid microbiological diagnosis of BSI in hematologic patients with FN. However, the clinical application needs pending further study. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Impact of Ptcy-Based Prophylaxis on Early Infectious Complications in Adults Undergoing Peripheral Blood Allo-HCT

INTRODUCTION PTCY-based prophylaxis was progressively implemented at our HCT Program for adults undergoing peripheral blood (PB) allo-HCT independently of the selected donor type. However, despite the efficacy provided in GVHD prevention, the incidences of infections among these patients remain high. Although PTCY-based prophylaxis is spreading rapidly in the allo-HCT Community very few studies so far have compared the incidence of infectious complications in patients receiving PTCY with that in patients receiving other prophylaxis. This study aims to investigate whether PTCY affects the probability of infectious complications diagnosed during the first 180 days after allo-HCT, and to explore the impact of these infections in post-transplant survival. METHODS Between the years 2012 and 2021, 426 consecutive adults with hematological malignancies underwent PB allo-HCT at or Institution, and all were included in the study. All patients received levofloxacin 500 mg daily from day +1 until neutrophil engraftment. No patient received letermovir. The study cohort was divided into two groups according to the GVHD prophylaxis: PTCY-based vs. others. The cumulative incidence functions (CIF) of infectious complications were estimated considering death as competing event, and after censoring the post-transplant follow-up at day +180. Moreover, in patients presenting more than one infection / viral reactivation during the study period, only the first episode was accounted as an event. Lastly, in the evaluation of post-transplant outcomes, patient´s follow-up was censored at 1 year. RESULTS 244 (57.2%) out of 426 patients received PTCY-based prophylaxis. Baseline characteristics were balanced, except for the proportion of allo-HCT performed from alternative donors (MMUD and haploidentical donors) that was higher in the PTCY-group than in the other (30.5% vs. 3.7% P<0.001). A total of 421 patient's primary engrafted. The median of days to neutrophil and platelet engraftment was higher in the PTCY-group (17 vs. 14 days, P<0.001 and 18 vs. 11, P<0.001). Patients receiving PTCY had less grade II-IV (Day +100 CIF: 23.8% vs 39.8%, P<0.001) and III-IV acute GVHD (Day +100 CIF: 5.7% vs. 13.8%, P=0.002), and moderate/severe chronic GVHD (6.4% vs. 31.6%, P<0.001) than patients receiving other prophylaxis. The estimated 1-year OS, RFS, NRM and CIR was 73.6%, 63.4%, 17.1% and 19.5% for patients receiving PTCY and 64.6% (P=0.048), 55.2% (P=0.090), 15.5% (P=0.473) and 29.3% (P=0.017) for those who did not. As reported in Figure 1, the proportions of bloodstream infections (BSI) were higher in patients receiving PTCY (Day +30 CIF: 39.3% vs. 14.9%, P<0.001). Rates of CMV reactivation (Day +180 CIF: 52.1% vs. 51.9%, P=0.358) and disease (Day +180 CIF: 9.1% vs. 10.5%, P=0.643) were comparable between the two groups. The proportions of VHH6 reactivation or infection (Day +180 CIF 10.7% vs.1.1%. P<0.001), and of grade 2-4 BK hemorrhagic cystitis (HC) (Day +180 CIF: 25.4% VS. 9.4%, P<0.001) were higher in the PTCY group. The median of days to peri-engraftment BSI, CMV reactivation, CMV disease and BK hemorrhagic cystitis diagnosis was shorter in the PTCY-group. As reported in Table 1, a relatively low day 30 infection-related mortality rate was associated with peri-engraftment BSI and viral complications, except for the CMV disease. Moreover, the diagnosis of CMV reactivation and disease and BK HC were found to be predictors for higher NRM and lower OS. CONCLUSIONS PTCY-based prophylaxis provides an effective GVHD prevention. However, its use increases the probability for BSI, diagnosed during the peri-engraftment phase, and BK HC and VHH6 infection during the early post-transplant period. Moreover, viral complications were diagnosed earlier in patients receiving PTCY. Rates of CMV reactivation and disease were high in the two groups, and importantly, the diagnosis of these complications had a negative impact on post-transplant outcomes. Prophylaxis with letermovir has been implemented at our program, and future analysis will explore the results derived from its implementation. Lastly, despite the low mortality rate directly attributed to BK HC, the presence of this complication increased the probability of mortality at 1 year. Based on these results, further refinements will be done focussed on preventing HC after PTCY administration. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Bacteriological Profile and their Antibiotic Susceptibility Pattern in Bloodstream Infections in a Tertiary Care Hospital in North India

Blood is a sterile, liquid connective tissue. When infected with microbes, grave consequences can occur, such as shock, multiple organ failure, disseminated intravascular coagulation (DIC), and death. The World Health Organization reported 49 million cases of sepsis and 11 million sepsis-related deaths in 2017, accounting for approximately 20% of deaths annually worldwide. Rapid identification of the causative organism and timely, appropriate treatment are required to reduce mortality due to bloodstream infections. This study was conducted to analyze the patterns of various bacteria causing bloodstream infections and their antibiotic susceptibility patterns. All blood samples received for diagnosing bloodstream infections at the Microbiology Department of Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, were included in the study, the duration of which was 1 year, from January to December 2020. Blood samples of 5–10 ml from adult and 5 ml from pediatric patients, were collected under aseptic conditions, stored in BACTEC bottles, and processed in an automated BACTEC system before antimicrobial therapy. After 7 days of incubation, if no microbial growth was observed, the sample was reported as sterile for aerobic organisms. When growth was observed, broth from positive blood culture bottles was subcultured on blood and MacConkey agar for identification and antimicrobial susceptibility testing using Vitek 2 according to CLSI (Clinical Lab Standard Institute) guidelines and the manufacturer’s instructions. A total of 441 (14.5%) bacteria were isolated from 3007 blood samples from patients with suspected bacteremia. Contamination was observed at a rate of 2.5%. Gram-positive cocci (49%) were the predominant organisms recovered, followed by Gram-negative bacilli (34%). Gram-positive cocci were coagulase-negative Staphylococci (46%), Staphylococcus aureus (7%), and Enterococcus spp. (6%). Among the Gram-negative bacilli, E.coli (14%), Klebsiella spp. (13%), Acinetobacter baumannii (7%), Pseudomonas spp. (7%), Salmonella typhi (2%), Enterobacter spp. (1%), and Serratia spp. (1%) and single isolates of Aeromonas spp., Morganella morgani, Pantoea spp., Proteus mirabilis, and Providentia rettgeri were identified. Linezolid, teicoplanin, and vancomycin were the most effective drugs for treating Gram-positive bacteremia. Tigecycline, carbapenems, and aminoglycosides were the most effective treatments for Gram-negative bacteremia. The results stress the need for continued screening and surveillance in routine blood culture techniques to start empiric therapy for bloodstream infections.

Transcriptome Mining to Identify Molecular Markers for the Diagnosis of Staphylococcus epidermidis Bloodstream Infections.

Bloodstream infections caused by Staphylococcus epidermidis are often misdiagnosed since no diagnostic marker found so far can unequivocally discriminate "true" infection from sample contamination. While attempts have been made to find genomic and/or phenotypic differences between invasive and commensal isolates, possible changes in the transcriptome of these isolates under in vivo-mimicking conditions have not been investigated. Herein, we characterized the transcriptome, by RNA sequencing, of three clinical and three commensal isolates after 2 h of exposure to whole human blood. Bioinformatics analysis was used to rank the genes with the highest potential to distinguish invasive from commensal isolates and among the ten genes identified as candidates, the gene SERP2441 showed the highest potential. A collection of 56 clinical and commensal isolates was then used to validate, by quantitative PCR, the discriminative power of the selected genes. A significant variation was observed among isolates, and the discriminative power of the selected genes was lost, undermining their potential use as markers. Nevertheless, future studies should include an RNA sequencing characterization of a larger collection of isolates, as well as a wider range of conditions to increase the chances of finding further candidate markers for the diagnosis of bloodstream infections caused by S. epidermidis.

Analysis of Blood Culture Collection and Laboratory Processing Practices in Israel

Blood culturing is a critical diagnostic procedure affecting patient outcomes and antibiotic stewardship. Although there are standards for blood culturing, the process is not often measured. To evaluate processes related to the diagnosis of bloodstream infection and compare them with best practices. A quality improvement study using laboratory data from January 1 to June 30, 2019, was conducted in 28 (96.6%) Israeli acute care hospitals. All blood cultures (BCs) performed on samples from adults and children in a period of 147 hospital-months were analyzed. Data analysis was performed from April 12, 2021, to September 9, 2022. True pathogen detection rate, contamination rate, proportion of adults with blood cultures performed, proportion of adult culturing episodes with only 1 set or bottle used, and median time of steps from sample collection to pathogen identification. The data set consisted of 348 987 BC bottles. Bloodstream infection was detected in a median of 6.7% (IQR, 5.8%-8.2%) of adult culturing episodes and 1.1% (IQR, 0.7%-1.9%) of pediatric episodes. Eleven of 27 hospitals (40.7%) with adult patients met the standard of a contamination rate of less than 3% and only 2 hospitals (7.4%) met the more stringent standard of less than or equal to 1% contamination rate. The percentage of adults with blood cultures ranged from 2.7% to 29.0% (mean [SD], 15.7% [6.0%]). There was an association between sampling rate and pathogen detection until BCs were performed in 17% of adult admissions. The percentage of solitary BCs ranged from 47.8% to 94.4%. An estimated 1745 of 7436 (23.5%) adult bloodstream infections went undetected because solitary BCs were performed, anaerobic bottles were not used, or BCs were not performed. Median processing time was 51.2 (IQR, 33.9-78.0) hours, 3 times the optimal time: 4.4 (IQR, 1.7-12.5) hours for the preanalytical stage, 15.9 (IQR, 10.2-23.6) hours from incubation to growth detection, 4.5 (IQR, 1.5-10.7) hours from detection to Gram stain, and 30.9 (IQR, 22.0-41.9) hours from detection to isolate identification. An 8.6-hour delay was related to off-hours operating of laboratories. The findings of this study suggest that the multistep process of blood culturing is not managed comprehensively in Israel, leading to poor clinical practices and delayed results.