Prospective observational pilot study of the T2Resistance panel in the T2Dx system for detection of resistance genes in bacterial bloodstream infections.

Early initiation of antimicrobial therapy targeting resistant bacterial pathogens causing sepsis and bloodstream infections (BSIs) is critical for a successful outcome. The T2Resistance Panel (T2R) detects the following resistance genes within organisms that commonly cause BSIs directly from patient blood samples: blaKPC, blaCTXM-14/15, blaNDM/bla/IMP/blaVIM, blaAmpC, blaOXA, vanA, vanB, and mecA/mecC. We conducted a prospective study in two major medical centers for the detection of circulating resistance genes by T2R in patients with BSIs. T2R reports were compared to antimicrobial susceptibility testing (AST), phenotypic identification, and standard molecular detection assays. Among 59 enrolled patients, 25 resistance genes were identified: blaKPC (n = 10), blaNDM/bla/IMP/blaVIM (n = 5), blaCTXM-14/15 (n = 4), blaAmpC (n = 2), and mecA/mecC (n = 4). Median time-to-positive-T2R in both hospitals was 4.4 hours [interquartile range (IQR): 3.65-4.97 hours] in comparison to that for positive blood cultures with final reporting of AST of 58.34 h (IQR: 45.51-111.2 hours; P < 0.0001). The sensitivity of T2R to detect the following genes in comparison to AST was 100% for blaCTXM-14/15, blaNDM/bla/IMP/blaVIM, blaAmpC, mecA/mecC and 87.5% for blaKPC. When monitored for the impact of significant antimicrobial changes, there were 32 events of discontinuation of unnecessary antibiotics and 17 events of escalation of antibiotics, including initiation of ceftazidime/avibactam in six patients in response to positive T2R results for blaKPC. In summary, T2R markers were highly sensitive for the detection of drug resistance genes in patients with bacterial BSIs, when compared with standard molecular resistance detection systems and phenotypic identification assays while significantly reducing by approximately 90% the time to detection of resistance compared to standard methodology and impacting clinical decisions for antimicrobial therapy. IMPORTANCE: This is the first reported study to our knowledge to identify key bacterial resistance genes directly from the bloodstream within 3 to 5 hours in patients with bloodstream infections and sepsis. The study further demonstrated a direct effect in modifying initial empirical antibacterial therapy in response to T2R signal to treat resistant bacteria causing bloodstream infections and sepsis.

Contaminant Organism Growth in Febrile Infants at Low Risk for Invasive Bacterial Infection.

In this multicenter, cross-sectional, secondary analysis of 4042 low-risk febrile infants, nearly 10% had a contaminated culture obtained during their evaluation (4.9% of blood cultures, 5.0% of urine cultures, and 1.8% of cerebrospinal fluid cultures). Our findings have important implications for improving sterile technique and reducing unnecessary cultures.

A multisite validation of a two hours antibiotic susceptibility flow cytometry assay directly from positive blood cultures.

BACKGROUND: Rapid antimicrobial susceptibility testing (AST) is urgently needed to provide safer treatment to counteract antimicrobial resistance. This is critical in septic patients, because resistance increases empiric therapy uncertainty and the risk of a poor outcome. We validate a novel 2h flow cytometry AST assay directly from positive blood cultures (PBC) by using a room temperature stable FASTgramneg and FASTgrampos kits (FASTinov® Porto, Portugal) in three sites: FASTinov (site-1), Hospital Ramon y Cajal, Madrid, Spain (site-2) and Centro Hospitalar S. João, Porto, Portugal (site-3). A total of 670 PBC were included: 333 spiked (site-1) and 337 clinical PBC (151 site-2 and 186 site-3): 367 gram-negative and 303 gram-positive. Manufacturer instructions were followed for sample preparation, panel inoculation, incubation (1h/37ºC) and flow cytometry analysis using CytoFlex (Site-1 and -2) or DxFlex (site-3) both instruments from Beckman-Coulter, USA. RESULTS: A proprietary software (bioFAST) was used to immediately generate a susceptibility report in less than 2 h. In parallel, samples were processed according to reference AST methods (disk diffusion and/or microdilution) and interpreted with EUCAST and CLSI criteria. Additionally, ten samples were spiked in all sites for inter-laboratory reproducibility. Sensitivity and specificity were >95% for all antimicrobials. Reproducibility was 96.8%/95.0% for FASTgramneg and 95.1%/95.1% for FASTgrampos regarding EUCAST/CLSI criteria, respectively. CONCLUSION: FASTinov® kits consistently provide ultra-rapid AST in 2h with high accuracy and reproducibility on both Gram-negative and Gram-positive bacteria. This technology creates a new paradigm in bacterial infection management and holds the potential to significantly impact septic patient outcomes and antimicrobial stewardship.

An improved protocol for bacteria identification by MALDI-TOF MS directly from positive blood cultures.

FASTinov® developed a rapid antimicrobial susceptibility test that includes the purification of a bacterial suspension directly from positive blood cultures (BC). In order to streamline laboratory workflow, the use of the bacterial suspension obtained through FASTinov® sample prep was tested for identification (ID) by matrix absorption laser deionization-time of flight mass spectrometry (MALDI-TOF MS) (Bruker) in 364 positive BC, and its accuracy assessed comparing with the MALDI-TOF MS ID of the next-day subcultured colonies. FASTinov sample prep was highly reliable for rapid ID directly from BC with proportion of agreement of 94.9% for Gram-positive and 96.3% for Gram-negative bacteria.

Deficits in blood culture collection in the emergency department if sepsis is suspected: results of a retrospective cohort study.

PURPOSE: Blood cultures (BCs) are key for pathogen detection in septic patients. We investigated the extent to which sampling was performed and what factors were associated with the absence of general or inadequate BC sampling. METHODS: We conducted a retrospective cohort study of hospitalized patients with sepsis admitted to one of three EDs in 2018. Primary outcome was the extent of general BC collection of at least 1 set. Secondary outcome was the extent of adequate BC sampling, defined as ≥ 2 sets before antibiotic therapy (AT). Multivariable logistic regression analysis was performed to identify factors associated with deficits in both outcomes. RESULTS: 1143 patients were analyzed. BCs were collected from 946 patients. Single BCs were taken from 520 patients, ≥ 2 sets from 426 patients. Overall, ≥ 2 BCs were taken from 349 patients before AT. BC sampling before AT occurred significantly more frequently when ≥ 2 BC sets were taken rather than a single one (81.9%, versus 68.4%, p < 0.001) and this also led to the highest pathogen detection rate in our cohort (65.6%). A body temperature of ≥ 38 °C was the a supporting factor for general and adequate BC collection in all three EDs. Retrospective analysis of 533 patients showed that the qSOFA score had no influence on general or adequate BC collection. CONCLUSION: Data on everyday clinical practice in the pre-analytical phase of microbiological diagnostics shows considerable deficits and indicates the need for more implementation of best practice. The variations identified in BC sampling between EDs should be further investigated.

Bile Culture May Guide Antibiotic Stewardship in Acute Bacterial Cholangitis.

BACKGROUND: Bile cultures are often sent with blood cultures in patients with acute bacterial cholangitis. AIMS: To assess the yield of blood and bile cultures in patients with cholangitis and the clinical utility of bile cultures in guiding therapy. METHODS: All patients diagnosed with cholangitis, based on the Tokyo 2013/2018 guidelines were recruited retrospectively over ten years. The clinical and investigation details were recorded. The results of bile and blood cultures including antibiotic sensitivity patterns were noted. The concordance of microorganisms grown in blood and bile cultures and their sensitivity pattern were assessed. RESULTS: A total of 1063 patients with cholangitis were included. Their mean age was 52.7 ± 14 years and 65.4% were males. Blood cultures were positive in 372 (35%) patients. Bile culture was performed in 384 patients with 84.4% being positive, which was significantly higher than the yield of blood culture (p < 0.001). Polymicrobial growth was more in bile (59.3%) than in blood cultures (13.5%, p < 0.001). E.coli, Klebsiella, Enterococcus and Pseudomonas were the four most common organisms isolated from both blood and bile. Extended spectrum betalactamase producing organisms were isolated in 57.7% and 58.8% of positive blood and bile cultures, respectively. Among 127 patients with both blood and bile cultures positive, complete or partial concordance of organisms was noted in about 90%. CONCLUSION: Bile and blood cultures have a similar microbial profile in most patients with cholangitis. As bile cultures have a significantly higher yield than blood cultures, they could effectively guide antimicrobial therapy, especially in those with negative blood cultures.

Pediatric blood cultures-turning up the volume: a before and after intervention study.

The major determinant of blood culture (BC) diagnostic performance is blood volume, and pediatric sample volumes are frequently low. We aimed to assess BC volumes in our institution, design an intervention to increase volumes, and assess its impact. All pediatric BCs submitted over a 7-month period to the microbiology laboratory in a university hospital (including emergency department, pediatric ward, and neonatal unit) were included. A pre-intervention period assessed current practice. A multi-faceted intervention (education, guideline introduction, active feedback strategies) was collaboratively designed by all stakeholders. Impact was assessed in a post-intervention period. The main outcome measures included the percentage of samples adequately filled using three measures of sample adequacy (1) manufacturer-recommended minimum validated volume-> 0.5 ml, (2) manufacturer-recommended optimal minimum volume-> 1.0 ml, (3) newly introduced age-specific recommendations. Three hundred ninety-eight pre-intervention and 388 post-intervention samples were included. Initial volumes were low but increased significantly post-intervention (median 0.77 ml vs. 1.52 ml), with multivariable regression analysis estimating volumes increased 89% post-intervention. There were significant increases in all measures of volume adequacy, including an increase in age-appropriate filling (20.4-53.1%), with less improvement in those aged > 3 years. Overall, 68.4% of pathogens were from adequately filled cultures, while 76% of contaminants were from inadequately filled cultures. A pathogen was detected in a higher proportion of adequately filled than inadequately filled cultures (9.4% vs. 2.2%, p < 0.001).  Conclusion: Blood volume impacts BC sensitivity, with lower volumes yielding fewer pathogens and more contaminants. Focused intervention can significantly improve volumes to improve diagnostic performance. What is Known: • Blood volume is the major determinant of blood culture positivity, and yet pediatric blood culture volumes are frequently low, resulting in missed pathogens and increased contamination. What is New: • Adequately filled (for age) blood cultures have a pathogen detection rate three times higher than inadequately filled blood cultures. • This interventional study shows that collaboratively designed multi-modal interventions including focus on accurate volume measurement can lead to significant increases in blood volumes and improve blood culture diagnostic performance.

Epidemiological patterns of candidaemia: A comprehensive analysis over a decade.

BACKGROUND: The prevalence of fungal bloodstream infections (BSI), especially candidaemia, has been increasing globally during the last decades. Fungal diagnosis is still challenging due to the slow growth of fungal microorganisms and need for special expertise. Fungal polymicrobial infections further complicate the diagnosis and extend the time required. Epidemiological data are vital to generate effective empirical treatment strategies. OBJECTIVES: The overall aim of this project is to describe the epidemiology of monomicrobial candidaemia and polymicrobial BSI, both with mixed fungaemia and with mixed Candida/bacterial BSIs. METHODS: We conducted a single-centre retrospective epidemiological study that encompasses 950,161 blood cultures during the years 2010 to 2020. The epidemiology of monomicrobial and polymicrobial candidaemia episodes were investigated from the electronic records. RESULTS: We found that 1334 candidaemia episodes were identified belonging to 1144 individual patients during 2010 to 2020. Candida albicans was the most prevalent species detected in candidaemia patients, representing 57.7% of these episodes. Nakaseomyces (Candida) glabrata and Candida parapsilosis complex showed an increasing trend compared to previous studies, whereas Candida albicans demonstrated a decrease. 19.8% of these episodes were polymicrobial and 17% presented with mixed Candida/bacterial BSIs while 2.8% were mixed fungaemia. C. albicans and N. glabrata were the most common combination (51.4%) in mixed fungaemia episodes. Enterococcus and Lactobacillus spp. were the most common bacteria isolated in mixed Candida/bacterial BSIs. CONCLUSIONS: Polymicrobial growth with candidaemia is common, mostly being mixed Candida/bacterial BSIs. C. albicans was detected in more than half of all the candidaemia patients however showed a decreasing trend in time, whereas an increase is noteworthy in C. parapsilosis complex and N. glabrata.

Routine Infectious Diseases Consultations on a Pediatric Cardiac Unit to Improve Positive Blood Culture Management.

Bacteremia can be life-threatening, and highly medicalized patients, such as those with complex congenital heart disease, are at high risk. Infectious diseases (ID) consultation is associated with improved outcomes in bacteremia. We noted an opportunity for improvement in management of positive blood cultures in our cardiac care unit (CCU). We completed a quality improvement project that included a single plan-do-study-act cycle consisting of a policy of routine ID consultation for all positive blood cultures events in the CCU. Our outcome measure of interest was percentage of appropriately managed blood culture events, the process measure was percentage of blood culture events for which the ID service was formally consulted, and the balancing measure was number of individual patients for whom the ID service was formally consulted. Appropriate antimicrobial management was determined via chart review by an ID physician. Data were analyzed via run chart and simple statistics. Following the intervention, the rate of appropriately managed positive blood culture events increased from a baseline of 86% to 98%, and the rate of ID consultation for these events increased from 75% to 98%. A shift was noted in run charts for both the outcome and process measures. There was an increase in patients for whom the ID service was consulted throughout the entire study period. We successfully implemented mandatory ID consultations in a CCU to increase proportion of appropriately managed blood cultures. While this intervention cannot be universally applied, others may find it useful in selected scenarios.

Evaluation of an automated rapid phenotypic antimicrobial susceptibility testing (ASTar, Q-linea AB) applied directly on blood cultures bottles positive for Gram-negative pathogens.

We evaluated the performance of a new rapid phenotypic antimicrobial susceptibility test (ASTar; Q-linea AB) on Gram-negative bacilli, directly from positive blood cultures bottles. MIC values obtained by the routine reference method (Microscan, Beckman Coulter) were compared to the ones provided by the tested method (ASTar). ASTar demonstrated an overall essential agreement of 98% and a category agreement of 96.1%. The overall rate of major errors and very major errors was 2.5% and 3.3%, respectively. ASTar can represent a rapid, simple, and reliable method to speed up information about antimicrobial susceptibility of Gram-negative pathogens from positive blood culture bottles.

Bacteremia caused by Veillonella parvula: Two case reports and a review of the literature.

Veillonella parvula is a non-motile Gram-negative coccus that forms part of the normal microbiota in several body sites and which has been rarely isolated as cause of infections in human population, particularly in bacteremias. Here we give the overview of characteristics of genus Veillonella and the summary of its role in infections, particularly in bacteremia. We additionally report two patients with bacteremia due to V. parvula. Two sets of blood cultures of each patient yielded a pure culture of an anaerobic microorganism identified as V. parvula by MALDI-TOF MS, and confirmed by 16S rRNA gene sequencing. The two patients were male and one of them had risk factors for anaerobic bacteremia. The isolates were susceptible to most antibiotics and the outcome was successful in both patients. Bacteremia due to V. parvula is still rare. MALDI-TOF MS appear to be an excellent tool for the correct identification of these species.

[Infections and fever]. / Infektion und Fieber.

Fever can be due to infectious or noninfectious causes and results from the body's natural response to exogenous or endogenous pyrogens. Laboratory tests including complete blood count, differential blood count, C­reactive protein, erythrocyte sedimentation rate and procalcitonin do not have sufficient sensitivity and specificity to definitively detect or rule out an infectious (bacterial, viral, parasitic) cause of fever. Blood cultures should be carried out when bacteremic or septic illnesses are suspected. Fever is not always present in infections and can be absent, especially in older and immunocompromised patients. If fever is suspected, core temperatures should be taken, e.g., rectally, orally or invasively. Depending on the clinical situation, infectious causes must be excluded as the most likely cause of an acutely occurring fever. The investigation of long-standing fever (fever of unknown origin, FUO) can be complex and some infectious diseases should first be ruled out, whereby a syndromic classification often helps to clarify the cause of the fever.

The Yield of One vs. Two Blood Cultures in Children: Under-Detection and Over-Testing.

We aimed to determine whether obtaining two blood cultures (BCs) instead of one improved the detection of bloodstream infections (BSIs) in children. For this descriptive study, we used surveillance data collected in 2019-2021 from all Israeli hospitals serving children. The sample included 178,702 culturing episodes. One BC was taken in 90.1% of all episodes and 98.2% of episodes in the emergency department. A true pathogen was detected in 1687/160,964 (1.0%) of single-culture episodes and 1567/17,738 (8.9%) of two-culture episodes (p < 0.001). The yield was significantly different even when considering only the first BC in two-culture episodes: 1.0% vs. 7.5%. Among 1576 two-culture episodes that were positive for a true pathogen, the pathogen was detected only in the second culture in 252 (16.0%). We estimated that if a second culture had been taken in all episodes, an additional 343 BSIs by a true pathogen would have been detected. Among 1086 two-culture episodes with commensal bacteria, the second BC was sterile in 530 (48.8%), suggesting contamination. A commensal was isolated in 3094/4781 (64.7%) positive single-culture episodes, which could represent BSI or contamination. The yield of a single BC bottle was low, reflecting both lower sensitivity of a single bottle and the taking of single bottles in patients with a low probability of BSI.

Is It Useful to Repeat Blood Cultures in Endocarditis Patients? A Critical Appraisal.

BACKGROUND: Previous guidelines for endocarditis have suggested repeating blood cultures until they become negative, with limited evidence. METHODS: Literature reviews were conducted (1) on the incidence of persistent bacteremia and association with outcome and (2) on timing of valve culture negativization to examine the claim for prolongation of antibiotic therapy starting from negative blood cultures. RESULTS: Persistent bacteremia and fever may be present in the first 3 days of endocarditis, despite treatment, and are more common in Staphylococcus (especially MRSA) and Enterococcus species. Persistent bacteremia (48-72 h), persistent infection (day 7), and new onset septic shock are related and predict in-hospital mortality. It is, however, persistent infection at day 7 and septic shock that primarily determine the infectious course of endocarditis, and not persistent bacteremia. Valve cultures at surgery become negative in most cases (>85-90%) after 14-21 days of antibiotic therapy, with no calculated benefit for prolonging therapy after 21 days. CONCLUSIONS: Persistent infection at 7 days after appropriate antibiotic therapy is a better key event for prognosis then positive or negative blood cultures at 48-72 h. Therapy prolongation from the day of negative blood cultures is not reasonable. There is no need to survey blood cultures in endocarditis patients after starting therapy.

Effectiveness of Multimodal Intervention to Improve Blood Culture Collection in a Tertiary Care Hospital.

Introduction and methods Blood culturing has become one of the backbone investigations for septicemia, fever of unknown origin, etc. This study was conducted to test the effect of multimodal interventions on the practical skills of healthcare workers (HCWs), raise awareness regarding the importance of aseptic blood culture collection practices, and increase compliance with the specific steps to be followed. Hence, this current interventional study was aimed at comparing the rate of isolation of contaminants grown among the blood culture specimens, assessing the knowledge, attitude, and practice (KAP) of HCWs collecting the blood culture specimen on various aspects of sample collection, educating the nursing staff regarding blood sample collection using a structured, pre-formed checklist, and emphasizing best practices for blood culture collection. All of the study's objectives were successfully met within the time frame specified. Using a pre-formed checklist and a Google form for KAP analysis eased the calculation. Results On analysis, the blood culture contamination rate in the pre-interventional phase dropped drastically from 6.16% to 3.03% in the post-interventional phase. The educational sessions conducted are a paramount reason for the reduction in the contamination rate. The HCWs were the least compliant towards the eighth step in the checklist (regarding palpation of skin); however, that too increased from 66.93% and 64.51% to a whopping 82.25% and 83.06%, respectively, with a chi-square value of 0.03 and a p-value of 0.85 (not significant). Conclusion Implementation of interventional studies as an audit like this in tertiary care hospitals can result in a significant reduction in blood culture contamination rates and can also improve the compliance of HCWs with blood culture protocols. This, in turn, can overall improve the effectiveness of blood culture (BC) testing and reduce mortality and morbidity in tertiary care hospitals. Further research can be conducted to brainstorm more methods to increase the compliance of HCWs. Better monitoring strategies can also be set to ensure low contamination rates. Additionally, some other methods can be derived to locate the source of contamination within the hospital environment and thus eliminate it. Similar interventions can be conducted for a longer duration of time to further reduce the blood culture contamination rate below 3% (as per the recommendations).

[Molecular diagnosis of bacteriaemia: benefits of using the FilmArray® BCID2 sepsis panel in a third level hospital]. / Diagnóstico molecular de bacteriemias: beneficios del empleo del panel de sepsis BCID2 de Filmarray® en un hospital de tercer nivel.

INTRODUCTION: Delay in initiating appropriate antimicrobial therapy prolongs hospitalization, increases in-hospital mortality, and raises economic costs. Currently, the identification and susceptibility testing of bacteria in positive blood cultures require a considerable amount of time. The objective of this study was to assess the impact of the BCID2 FilmArray® (FA) panel on the timing of appropriate antimicrobial therapy and potential antimicrobial costs. METHODS: This is a retrospective observational study focused on positive blood cultures in hospitalized patients. FA processing was conducted concurrently with routine sample processing. Changes in antibiotic treatments based on FA results were evaluated, and the reduction in antimicrobial therapy duration and associated cost savings were calculated. RESULTS: Eighty-seven bacteremia episodes were analysed. In 42 (48%) of them antimicrobial therapy was de-escalated to narrower spectrum agents, while in 7 (8%) therapy was escalated to broader spectrum antimicrobials. Additionally, in 8 (9%) antimicrobials were switched without changing spectrum and in 30 (34%) no changes were made based on FA results. Antimicrobial changes were made 2.3 days faster than with routine sample processing resulting in calculated potential savings of US$ 7408. CONCLUSION: The implementation of FA facilitated a faster administration of appropriate antimicrobial therapy, leading to a reduction in the duration of broadspectrum empirical antimicrobial therapy and subsequent economic savings.

Introducción: Los retrasos en el tratamiento antimicrobiano adecuado de las bacteriemias prolongan la estadía hospitalaria, aumentan la mortalidad e incrementan los costos. Aún hoy en día se requiere un tiempo considerable para obtener la identificación y antibiograma de los microorganismos en los hemocultivos positivos. El objetivo fue evaluar el impacto de la implementación del panel BCID2 de FilmArray® (FA) sobre el tiempo de inicio de tratamientos antimicrobianos adecuados y sobre los costos potenciales de los mismos. Métodos: Estudio observacional retrospectivo de los hemocultivos positivos de pacientes hospitalizados, procesados por FA y por metodología tradicional. Se evaluaron los cambios de antimicrobianos en base a los resultados del FA. Se calcularon los días de reducción de tratamiento antimicrobiano y el ahorro potencial en el uso de los mismos, teniendo en cuenta también los costos del FA. Resultados: Se analizaron 87 episodios de bacteriemia. En 42 (48.3%) de ellos se desescaló el tratamiento a antimicrobianos de menor espectro, en 7 (8%) se escaló a antimicrobianos de mayor espectro, en 8 (9.2%) se cambió el antimicrobiano sin variar el espectro y en 30 (34.5%) no se realizaron cambios con los resultados del FA. Los cambios de antimicrobianos se realizaron en promedio 2.3 días más rápido que con los métodos convencionales. Se calculó un ahorro potencial de US$ 7408. Conclusión: La implementación del panel BCID2 de FilmArray® permitió adecuar los tratamientos antimicrobianos más rápidamente acortando la duración de los tratamientos empíricos de amplio espectro, lo cual resultó costo-efectivo.

Evaluation of Quantamatrix dRASTTM system for rapid antimicrobial susceptibility testing of bacterial isolates from positive blood cultures, in comparison with commercial Micronaut broth microdilution system.

Antimicrobial susceptibility testing (AST) from blood culture (BC) may take several days, limiting the eventual impact on antimicrobial stewardship. Hence, rapid AST systems represent a valuable support in shorting the time-to-response. In this work, the Quantamatrix dRASTTM system (dRAST) was evaluated for rapid AST on 100 monomicrobial BCs (50 Gram-negatives and 50 Gram-positives), including several isolates with clinically relevant resistance mechanisms. AST results were provided in 6-hours, on average. Compared to Micronaut (Merlin) system based on broth microdilution, dRAST exhibited an overall categorical agreement of 92.5 %, essential agreement of 89.0 %, and mean bias of 15.9 %. Category overestimation (potentially leading to unnecessary high-dosage treatment or to exclude active agents) and category underestimation (potentially leading to underdosing or using ineffective agents) were observed in 4.3 % and 3.1 % of cases, respectively. Even though several issues were reported, results confirmed the potential contribution of dRAST to shorten the BCs clinical microbiology workflow and management.

Comparison of time-to-detection of Mindray TDR and BacT/ALERT®3D blood culture systems using simulated blood cultures.

PURPOSE: Blood culture (BC) is the standard for diagnosing bloodstream infections. Available blood culture (BC) systems have been developed to shorten the time to detection (TTD) of positive BCs. This study aimed to evaluate the performance of the Mindray TDR automatic BC system by comparing it with the BacT/ALERT®3D system. METHODS: Sixteen reference strains and 14 clinical isolates were used. Serial dilutions were prepared from all bacterial and yeast colonies with a final concentration of 100 CFU/ml and 10 CFU/ml. The prepared solutions were simultaneously inoculated into the bottles of both systems and placed in blood culture devices. RESULTS: Three hundred and fifty-two (176 BacT/ALERT®3D and 176 Mindray TDR-X060) blood culture bottles were evaluated, 336 aerobic and 16 anaerobic. At both 10 CFU/ml and 100 CFU/ml dilution, there was no significant difference between the two systems in terms of mean detection times for all isolates (p = 0.965, p = 0.245). When evaluated according to the type of organism, the detection time of gram-positive bacteria at 10 CFU/ml dilution was significantly shorter in the BacT/ALERT system (p = 0.019), whereas detection time for yeasts was significantly shorter with the Mindray system (p = 0.047). The number of anaerobic bacteria was too small to draw statistical conclusions, but we observed a trend of shorter detection times in the Mindray TDR-X060 system. CONCLUSION: Two systems with similar operating principles showed different concentrations-dependent performances in terms of positivity detection times depending on the type of microorganism. Mindray TDR-X060 system has been found to be safe to use at high concentrations with this at lower concentrations further comparative studies are needed on the newly introduced Mindray system.