Evaluation of the Vitek MS and the MALDI Biotyper systems for the identification of less commonly isolated but clinically relevant anaerobes and facultative anaerobes.

The Vitek MS and MALDI Biotyper systems were evaluated for the identification of 221 strains belonging to less commonly isolated anaerobes and facultative anaerobes. Identifications were performed using direct deposit (DD), on-target extraction (FA) and full extraction (EXT). After DD, 29.9% and 34.3% of Gram-positive isolates (n = 137) as well as 36.9% and 58.3% of Gram-negative isolates (n = 84) were identified at the species-level with the Vitek-MS and the Biotyper system, respectively. The rates of correct species identification with the Biotyper system were significantly increased after extraction for Gram-positive isolates (FA: 75.2%, EXT: 78.1%) and Gram-negative isolates (FA: 72.6%, EXT: 78.6%). Extraction permitted to achieve higher correct species identification rates only for Gram-positive isolates (FA: 35.8%, EXT: 36.5%) with the Vitek MS. Thus, the accuracy of both systems needs to be further increased by expanding the databases. In the meantime, we recommend using a preliminary extraction step to obtain reliable results at least for the identification of Gram positive anaerobic bacteria with both systems.

Comparison of Vitek MS and MALDI Biotyper for Identification of Actinomycetaceae of Clinical Importance.

The Vitek MS in vitro diagnostic (IVD) and MALDI Biotyper IVD systems were evaluated for the identification of 158 strains of Actinomycetaceae. Correct species-level identification rates of 60.7% and 58.2% were obtained with the Vitek MS system after direct deposit and with the MALDI Biotyper system after on-plate formic acid treatment, respectively.

Diagnostic Accuracy of Procalcitonin for Predicting Blood Culture Results in Patients With Suspected Bloodstream Infection: An Observational Study of 35,343 Consecutive Patients (A STROBE-Compliant Article).

Previous studies have suggested that procalcitonin is a reliable marker for predicting bacteremia. However, these studies have had relatively small sample sizes or focused on a single clinical entity. The primary endpoint of this study was to investigate the diagnostic accuracy of procalcitonin for predicting or excluding clinically relevant pathogen categories in patients with suspected bloodstream infections. The secondary endpoint was to look for organisms significantly associated with internationally validated procalcitonin intervals. We performed a cross-sectional study that included 35,343 consecutive patients who underwent concomitant procalcitonin assays and blood cultures for suspected bloodstream infections. Biochemical and microbiological data were systematically collected in an electronic database and extracted for purposes of this study. Depending on blood culture results, patients were classified into 1 of the 5 following groups: negative blood culture, Gram-positive bacteremia, Gram-negative bacteremia, fungi, and potential contaminants found in blood cultures (PCBCs). The highest procalcitonin concentration was observed in patients with blood cultures growing Gram-negative bacteria (median 2.2 ng/mL [IQR 0.6-12.2]), and the lowest procalcitonin concentration was observed in patients with negative blood cultures (median 0.3 ng/mL [IQR 0.1-1.1]). With optimal thresholds ranging from ≤0.4 to ≤0.75 ng/mL, procalcitonin had a high diagnostic accuracy for excluding all pathogen categories with the following negative predictive values: Gram-negative bacteria (98.9%) (including enterobacteria [99.2%], nonfermenting Gram-negative bacilli [99.7%], and anaerobic bacteria [99.9%]), Gram-positive bacteria (98.4%), and fungi (99.6%). A procalcitonin concentration ≥10 ng/mL was associated with a high risk of Gram-negative (odds ratio 5.98; 95% CI, 5.20-6.88) or Gram-positive (odds ratio 3.64; 95% CI, 3.11-4.26) bacteremia but dramatically reduced the risk of PCBCs or fungemia. In this large real-life setting experience with more than 35,000 patients, procalcitonin was highly effective at excluding bloodstream infections regardless of pathogen categories. The results from our study are limited by its cross-sectional design and deserve to be validated in prospective longitudinal studies.

Comparison of seven methods for extraction of bacterial DNA from fecal and cecal samples of mice.

Analysis of bacterial DNA from fecal samples of mice is commonly performed in experimental studies. Although DNA extraction is a critical step in various molecular approaches, the efficiency of methods that may be used for DNA extraction from mice fecal samples has never been evaluated. We compared the efficiencies of six widely used commercial kits (MasterPure™ Gram Positive DNA Purification Kit, QIAamp® DNA Stool Mini Kit; NucliSENS® easyMAG®, ZR Fecal DNA MiniPrep™, FastDNA® SPIN Kit for Feces and FastDNA® SPIN Kit for Soil) and a non-commercial method for DNA isolation from mice feces and cecal contents. DNA quantity and quality were assessed by fluorometry, spectrophotometry, gel electrophoresis and qPCR. Cell lysis efficiencies were evaluated by qPCR targeting three relevant bacteria in spiked specimens. For both feces and intestinal contents, the most efficient extraction method was the FastDNA® SPIN Kit for Soil.

Cardiac device-related endocarditis caused by Paenibacillus glucanolyticus.

We report the first case of Paenibacillus glucanolyticus infection in a 65-year-old patient with type 2 diabetes who developed a cardiac device-related endocarditis. The identification of the isolate was performed using phenotypic methods, including mass spectrometry-based methods, and 16S rRNA gene sequencing.