Sporulation is dispensable for the vegetable-associated life cycle of the human pathogen Bacillus cereus.

Bacillus cereus is a common food-borne pathogen that is responsible for important outbreaks of food poisoning in humans. Diseases caused by B. cereus usually exhibit two major symptoms, emetic or diarrheic, depending on the toxins produced. It is assumed that after the ingestion of contaminated vegetables or processed food, spores of enterotoxigenic B. cereus reach the intestine, where they germinate and produce the enterotoxins that are responsible for food poisoning. In our study, we observed that sporulation is required for the survival of B. cereus in leaves but is dispensable in ready-to-eat vegetables, such as endives. We demonstrate that vegetative cells of B. cereus that are originally impaired in sporulation but not biofilm formation are able to reach the intestine and cause severe disorders in a murine model. Furthermore, our findings emphasise that the number of food poisoning cases associated with B. cereus is underestimated and suggest the need to revise the detection protocols, which are based primarily on spores and toxins.

Genetic variants in the LPL and GPIHBP1 genes, in patients with severe hypertriglyceridaemia, detected with high resolution melting analysis.

INTRODUCTION: Pathogenic variants in lipoprotein lipase (LPL) and glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1) have been described in patients with severe hypertriglyceridaemia. We aimed to optimise high resolution melting (HRM) assays to detect the presence of functional variants in these genes. METHODS: One hundred and sixteen patients with severe hypertriglyceridaemia were studied. HRM assays were optimised to scan exons and splice junctions in LPL and GPIHBP1. Sanger sequencing was the reference method. Next-generation-sequencing (NGS) was performed in five patients, including one with Familial Chylomicronemia syndrome (FCS). RESULTS: We identified 15 different variants in LPL and 6 in GPIHBP1. The variants revealed with NGS were also detected with HRM, including a rare premature stop codon in LPL (p.Trp421*) and two LPL pathogenic variants in the patient with FCS (p.His80Arg + p.Gly215Glu). Having multiple functional variant alleles was associated with pancreatitis onset at younger ages and higher baseline triglycerides. CONCLUSIONS: Our HRM assays detected the presence of functional gene variants that were confirmed with Sanger and NGS sequencing. The presence of multiple functional variant alleles was associated with differences in the clinical profile. Therefore, these assays represent a reliable, cost-effective tool that can be used to complement the NGS approach for gene scanning.

Plasma inorganic pyrophosphate and alkaline phosphatase in patients with pseudoxanthoma elasticum.

BACKGROUND: Inorganic pyrophosphate (PPi) plays a major role inhibiting dystrophic calcification. The aim was to analyze levels of PPi in patients having pseudoxanthoma elasticum (PXE), and controls as well as the enzymes who regulate the PPi plasma concentration. METHODS: We collected fasting blood samples from PXE patients and age- and sex-matched controls in ethylenediamine tetraacetic acid (EDTA) and citrate-theophylline-adenosine-dipyridamole (CTAD) containing tubes. We measured PPi, ENPP1 mass and activity, alkaline phosphatase (AP) and tissue non-specific alkaline phosphatase (TNAP), CD73 and Human Platelet Factor-4 (CXCL4). RESULTS: PPi in EDTA and CTAD samples were lower in PXE subjects than in controls (1.11±0.26 vs. 1.43±0.41 µM/L and 0.35±0.15 vs. 0.61±0.18 µM/L respectively, P<0.05). TNAP and liver TNAP activities were also higher in PXE than in controls (80.3±27.0 vs. 63.3±16.4 UI/L and 25.6±14.9 vs. 12.9±9.2 UI/L respectively, P<0.05). ENPP1 mass and activity as well as CD73 were almost identical. There was a weak but significant inverse correlation between TNAP activity and PPi levels (Pearson correlation -0.379, P<0.05) in both groups. CONCLUSIONS: High TNAP activity seems to contribute to low plasma levels of PPi in subjects with PXE, reinforcing the idea that pharmacological reduction of TNAP activity may help to reduce dystrophic calcification in PXE patients.