Rapid identification of Salmonella serovars Enteritidis and Typhimurium using whole cell matrix assisted laser desorption ionization - Time of flight mass spectrometry (MALDI-TOF MS) coupled with multivariate analysis and artificial intelligence.

Salmonella is a common food-borne pathogen with Enteritidis and Typhimurium being among the most important serovars causing numerous outbreaks. A rapid method was investigated to identify these serovars using whole-cell MALDI-TOF MS coupled with multivariate analysis and artificial intelligence and 113 Salmonella strains, including 38 Enteritidis (SE), 38 Typhimurium (ST) and 37 strains from 32 other Salmonella serovars (SG). Datasets of ions (presence/absence) with high discriminative power were created using newly developed criteria and subject to multivariate analyses and eight artificial intelligence (AI) tools. Principal Component Analysis based on 55 or 88 selected ions separated SE, ST and SG without overlap on the first three principal components. Datasets were partitioned using five partitioning methods with 70% of samples for AI model training and 30% for validation. Of the eight AI models evaluated, high performance (HP) SVM and HP Neural were the top performers, identified three serovar groups 97% correctly on average (range 82%-100%) according to the validation results. Selection of serovar specific ions facilitated differentiation of serotypes using unsupervised model PCA and improved the accuracy of classification using AI significantly (p < 0.01). MALDI-TOF MS incorporated with advanced data processing and classification tools is a promising method to allow rapid identification of Salmonella serovars of concern in routine diagnostic laboratories.

Genomics accurately predicts antimicrobial resistance in Staphylococcus pseudintermedius collected as part of Vet-LIRN resistance monitoring.

Whole-genome sequencing (WGS) has changed our understanding of bacterial pathogens, aiding outbreak investigations and advancing our knowledge of their genetic features. However, there has been limited use of genomics to understand antimicrobial resistance of veterinary pathogens, which would help identify emerging resistance mechanisms and track their spread. The objectives of this study were to evaluate the correlation between resistance genotypes and phenotypes for Staphylococcus pseudintermedius, a major pathogen of companion animals, by comparing broth microdilution antimicrobial susceptibility testing and WGS. From 2017-2019, we conducted antimicrobial susceptibility testing and WGS on S. pseudintermedius isolates collected from dogs in the United States as a part of the Veterinary Laboratory Investigation and Response Network (Vet-LIRN) antimicrobial resistance monitoring program. Across thirteen antimicrobials in nine classes, resistance genotypes correlated with clinical resistance phenotypes 98.4 % of the time among a collection of 592 isolates. Our findings represent isolates from diverse lineages based on phylogenetic analyses, and these strong correlations are comparable to those from studies of several human pathogens such as Staphylococcus aureus and Salmonella enterica. We uncovered some important findings, including that 32.3 % of isolates had the mecA gene, which correlated with oxacillin resistance 97.0 % of the time. We also identified a novel rpoB mutation likely encoding rifampin resistance. These results show the value in using WGS to assess antimicrobial resistance in veterinary pathogens and to reveal putative new mechanisms of resistance.

Splenic conservation: variation between pediatric and adult trauma centers.

OBJECTIVES: Nonoperative management of hemodynamically stable children and adolescents with splenic injury regardless of grade has become standard; however, numerous studies have shown a wide variation in management. We compared the treatment and outcomes of adolescent splenic injuries in our region, which includes a pediatric level I trauma center (PTC) and an adult level I trauma center (ATC). METHODS: A retrospective review of the trauma registry was performed on patients 14 to 17 y old with blunt splenic injury admitted to either the local PTC or ATC from January 1999 through December 2010. Demographics, interventions, and hospital course were recorded and compared using Fisher exact, Student t-test, and multivariate analysis. RESULTS: Eighty-six adolescent patients presenting to the PTC and 65 patients presenting to the ATC met the criteria over the 12-y period. Although the ATC received more significantly injured and slightly older patients, logistic multivariate analysis demonstrated that the location of presentation was the only independent factor associated with splenectomy (P = 0.0015). A higher injury severity score was associated with a longer length of stay (LOS), but the nonoperative approach was not associated with a longer LOS (P = 0.96). CONCLUSIONS: Our study demonstrates that the location of presentation was independently associated with splenectomy while controlling for a higher injury severity score at the ATC. With the higher percentage of nonoperative management, treatment at the PTC was not associated with an increased LOS (total or intensive care unit).

Expression of VE-cadherin in zebrafish embryos: a new tool to evaluate vascular development.

We have identified the zebrafish homologue of VE-cadherin and documented its expression in the developing vascular system. The zebrafish VE-cadherin gene is specifically expressed in the vascular endothelial cell lineage beginning with the differentiation and migration of angioblasts and persists throughout vasculogenesis, angiogenesis, and endocardium development. Staining zebrafish embryos by whole-mount in situ hybridization with the VE-cadherin probe provides a method to screen embryos for vascular defects. To illustrate this utility, we used VE-cadherin expression to demonstrate a conservation of vascular endothelial growth factor-A (VEGF-A) function. The morpholino antisense oligonucleotide knockdown of VEGF-A function in zebrafish embryos results in a loss of angiogenic blood vessels, as indicated by the lack of VE-cadherin expression in the intersegmental vasculature. This loss can be restored in embryos supplemented with either zebrafish or human VEGF-A, the latter indicating that genes crucial to angiogenesis have highly conserved functional activities in vertebrates.