Rapid Sepsityper in clinical routine: 2 years' successful experience

Enhancing pneumococcal bacteraemia diagnosis: A comparative assessment of culture-independent assays (MALDI-TOF-MS Sepsityper® module and a lateral flow inmunochromatography test)

INTRODUCTION

Pneumococcal bacteraemia is a major contributor to global morbidity and mortality. Traditional culture-based methods lack sensitivity and are time-consuming. This study aimed to assess the effectiveness of two culture-independent assays, the MALDI-TOF-MS Sepsityper® module and the lateral flow inmunochromatography test (LFICT) with the Standard F® Streptococcus pneumoniae, directly from positive blood culture (BC) bottles.

METHODS

A prospective study was conducted from December 2021 to July 2022. For all BC positives for S. pneumoniae a double centrifugation protocol was implemented. The resulting pellet was subsequently processed using both techniques.

RESULTS

The LFICT showed exceptional performance with 100% sensitivity and specificity, outperforming the MALDI-TOF-MS Sepsityper® module, which achieved 85.2% sensitivity and 100% specificity. Nevertheless, the combination of these assays offers a robust and comprehensive approach to diagnosis.

CONCLUSIONS

The simultaneous use of both techniques offers a promising alternative that can be integrated into routine practices directly from BC samples.

Direct Species Identification in Positive Blood Culture Bottles From Patients With Hematologic Malignancies

Background In patients with hematologic malignancies, faster species identification is particularly important in the management of bloodstream infection because of their immunocompromised and neutropenic status. In the present study, we analyzed direct species identification in patients with hematologic malignancies, and the factors that might influence the results of species identification. Methods We performed direct species identification using a Sepsityper® kit (Bruker Corporation, Billerica, Massachusetts, United States) and compared the results with a conventional method in patients with hematologic malignancies. Forty-five positive blood culture bottles containing single microorganisms from 37 patients were analyzed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). And patients' clinical data were compared between the groups with spectral scores at acceptable and unacceptable levels. Results Direct species identification correctly identified 42 of 45 isolates and three were misidentified. While 35 of 45 isolates showed a spectral score ≥1.7 (acceptable identification), 10 isolates had a spectral score <1.7 (unacceptable identification) including three misidentified isolates. The group with a spectral score ≥1.7 had significantly lower white blood cell (p<0.01), neutrophil (p<0.01), and platelet (p<0.01) counts in addition to more frequent central venous (CV) line insertion (p=0.01). Multivariate analysis revealed that pathogen type (gram-positive or negative) and CV line insertion were associated with spectral scores. Conclusion Direct species identification using the Sepsityper kit is an upcoming approach for blood culture bottles, which were flagged as positive even in patients with hematologic malignancies when the spectral score was ≥ 1.7. Our study also indicates that direct identification is more accurate in patients with CV lines, and may be less accurate when gram-positive bacteria are detected.

Evaluation of the Rapid Sepsityper protocol and specific MBT-Sepsityper module for the identification of bacteremia and fungemia using Bruker Biotyper MALDI-TOF MS

The rapid identification method, the Rapid Sepsityper protocol with a specific MBT-Sepsityper module (Bruker Daltonics), based on the MALDI Biotyper platform, accurately identified 93.5% (116/124) of microorganisms at the species level in the 124 flagged blood culture samples from patients with monomicrobial bloodstream infections. Gram-negative bacilli (95.6%, 43/45) had a higher identification rate than Gram-positive cocci (93.3%, 70/75) and yeasts (75%, 3/4). The Rapid Sepsityper protocol displayed poor identification performance for polymicrobial samples.

Identification of micro-organism from positive blood cultures: comparison of three different short culturing methods to the Rapid Sepsityper workflow

Sepsis is one of the leading causes of death worldwide. The rapid identification (ID) of the causative micro-organisms is crucial for the patients' clinical outcome. MALDI-TOF MS has been widely investigated to speed up the time-to-report for ID from positive blood cultures, and many different procedures and protocols were developed, all of them attributable either to the direct separation of microbial cells from the blood cells, or to a short subculture approach. In this study, the Rapid Sepsityper workflow (MBT Sepsityper IVD Kit, Bruker Daltonics GmbH and Co. KG, Bremen, Germany) was compared to three different short subculturing methods, established into the routine practice of three different clinical microbiology laboratories. A total of N=503 routine samples were included in this study and tested in parallel with the two approaches. Results of the rapid procedures were finally compared to routine proceedings with Gram-staining and overnight subculture. Among monomicrobial samples, the Rapid Sepsityper workflow enabled overall the correct identification of 388/443 (87.6 %) micro-organisms, while the short subculturing methods of 267/435 (61.8 %). Except for the performance with Streptococcus pneumoniae, in each one of the three sites the Rapid Sepsityper workflow proved to be superior to the short subculture method, regardless of the protocol applied, and it delivered a result from 1 to 5 h earlier.

MALDI-Based Mass Spectrometry in Clinical Testing: Focus on Bacterial Identification

The term “proteome” refers to the total of all proteins expressed in an organism. The term “proteomics” refers to the field of research that includes not only information on the expression levels of individual proteins, but also their higher-order structures, intermolecular interactions, and post-translational modifications. The core technology, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), is available for protein analysis thanks to the work of Koichi Tanaka and John Fenn, who were awarded the Nobel Prize in Chemistry in 2002. The most successful proteome analysis in clinical practice is rapid microbial identification. This method determines the bacterial species by comparing the proteome profile of the bacteria obtained by matrix-assisted laser desorption ionization-time of flight MS (MALDI-TOF MS) with a database. MS is superior in simplicity, speed, and accuracy to classic speciation by staining and phenotyping. In clinical microbiology, MS has had a large impact on the diagnosis and treatment of infectious disease. Early diagnosis and treatment of infectious disease are important, and rapid identification by MALDI-TOF MS has made a major contribution to this field.

Direct microorganism species identification and antimicrobial susceptibility tests from positive blood culture bottles using rapid Sepsityper Kit

INTRODUCTION

We evaluated the performance of Rapid Sepsityper Kit in species identification (ID) and antimicrobial susceptibility testing (AST).

METHODS

Positive blood culture bottles (n = 227) containing single microorganisms were enrolled. We compared the direct method using Rapid Sepsityper Kit for ID and AST with the conventional method. The analyses of ID and AST were performed using MALDI Biotyper and BD Phoenix platform, respectively.

RESULTS

The direct ID method correctly identified 89.4% (203/227) of samples, and Gram-negative bacilli (95.2%) had a higher ID rate than Gram-positive cocci (84.4%). Five cases were misidentified, and non-acceptable identification was high among Streptococcus species. Direct AST results were obtained from 168 isolates. Non-acceptable ID occurred among 24 isolates; 4 Streptococcus species, and 31 isolates, which did not grow in the direct AST method, were excluded. A total of 1714 antibiotic susceptibility tests (625 from 69 Gram-positive cocci and 1089 from 99 Gram-negative bacilli) were performed. The direct AST methods showed 98.3% (1685/1714) of categorical agreement (CA), 0.7% (12/1714) of very major errors, 0.2% (4/1714) of major errors, and 0.8% (13/1714) of minor errors. Complete CA was obtained for methicillin-resistant Staphylococcus aureus and extended-spectrum beta-lactamase-producing Escherichia coli.

CONCLUSIONS

The direct ID method using Rapid Sepsityper Kit and the direct AST method in combination with the BD Phoenix platform, which was associated with a reduction of turnaround time, may be a reliable approach for blood culture bottles. However, additional validation and further improvements, especially for Gram-positive cocci, would have an impact on microbiological diagnoses.

Successfully treated infected aneurysm caused by Listeria monocytogenes

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L. monocytogenes causes seriously infected aneurysms in immunocompromised hosts.

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Cephalosporins are used as an empirical therapy for infected aneurysms.

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L. monocytogenes has intrinsic resistance to cephalosporins.

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Rapid diagnostic testing is helpful in patients with life-threatening listeriosis.

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A short course of preoperative therapy with appropriate antibiotic is beneficial.

Infected aneurysms caused by Listeria monocytogenes are extremely rare. Therefore, there is no standard procedure for their diagnosis and treatment. A 76-year-old Japanese man with diabetes and hypertension was diagnosed with a left common iliac aneurysm caused by L. monocytogenes, using multidetector computed tomographic angiography and rapid diagnostic testing of the positive blood culture. He was successfully treated with a combination of ampicillin administration, timely surgical debridement, and in-situ Y-graft placement with revascularization and omental implantation. Vancomycin and third-generation cephalosporins, to which L. monocytogenes is resistant, are used as an empirical regimen for infected aneurysms. Therefore, the use of a rapid diagnostic testing is important as it identifies L. monocytogenes within 24 h from obtaining the blood cultures, and guides the administration of the appropriate antibiotics. In-situ Y-graft placement restores nearly normal blood flow, following the confirmation of negative conversion of blood culture in response to the intensive intravenous ampicillin therapy. Appropriate and timely microbiological examinations, in addition to radiographic examinations, can be the key for selecting the optimal therapeutic procedures for each patient and achieving the best possible outcomes.