The SOS response including two main proteins LexA and RecA, maintains the integrity of bacterial genomes after DNA damage due to metabolic or environmental assaults. Additionally, derepression of LexA-regulated genes can result in mutations, genetic exchange and expression of virulence factors. Here we describe the first comprehensive description of the in silico LexA regulon in Clostridium difficile, an important human pathogen.

Background: Short-chain fatty acids (SCFAs), which are produced by the microbial fermentation of undigested carbohydrates, play an important role in the metabolism and physiology of the host. SCFAs are involved in the regulation of maternal metabolism during pregnancy and influence weight gain, glucose metabolism, and metabolic hormones. Methods: In 2017, women who were treated for gestational diabetes mellitus (GDM) at the University Medical Centre Ljubljana were invited to participate in a longitudinal study. A total of 45 women were included in this study and comprehensively phenotyped. During the second and third trimester of pregnancy, the women with GDM provided fecal samples for SCFA analysis. The samples were analyzed by high-performance liquid chromatography for the simultaneous determination of acetate, propionate, and butyrate. Results: SCFA concentrations in feces differed between overweight/obese and normal-weight women with GDM. Acetate and propionate concentrations were significantly higher in pregnant women who were overweight or obese before pregnancy compared to normal-weight women but butyrate concentrations were not. Butyrate was elevated in the third trimester in the group with excessive gestational weight gain. Conclusions: The relationship between SCFAs and obesity is complex, and the association between SCFAs and GDM remains to be clarified. Regardless of the conflicting publications on the role of SCFAs, our study showed that higher acetate and propionate levels were associated with the weight categories of overweight or obesity before pregnancy and higher butyrate levels were associated with excessive gestational weight gain.

Urinary tract infections can be severe, sometimes fatal, diseases whose etiological pathogens are predominantly uropathogenic strains of E. coli (UPEC). To investigate the UPEC pathogenesis, several models have already been established with minor or major disadvantages. The aim was to develop a simple, fast, and inexpensive biomimetic in vitro model based on normal porcine urothelial (NPU) cells that are genetically and physiologically similar to human bladder urothelium and to perform basic studies of E. coli pathogenicity. Initially, the model was tested using a set of control E. coli strains and, subsequently, with human E. coli strains isolated either from patients with urinary infections or from the feces of healthy individuals. A drop in viability of NPU cells was used as a measure of the pathogenicity of the individual strain tested. To visualize the subcellular events, transmission and scanning electron microscopy was performed. The strains were tested for the presence of different virulence-associated genes, phylogroup, type of core lipid, O-serotype, and type of lipopolysaccharide and a statistical analysis of possible correlations between strains’ characteristics and the effect on the model was performed. Results showed that our model has the discriminatory power to distinguish pathogenic from non-pathogenic E. coli strains, and to identify new, potentially pathogenic strains.

Background/Objectives: Gestational diabetes mellitus (GDM) is associated with altered maternal gut microbiota and increased risk of large-for-gestational age (LGA) births. The contribution of gut microbiota to fetal overgrowth in GDM, independent of glycemic control, remains unclear. Methods: In this pilot longitudinal study, the gut microbiota of 18 women with GDM was followed from the second (2T) to the third trimester (3T). Maternal fecal samples were analyzed by 16S rRNA gene sequencing, and associations between microbial profiles and infant birth weight were examined. In addition, these associations were adjusted for pre-pregnancy body mass index (BMI) and gestational weight gain (GWG). Results: Maternal gut microbiota of LGA infants exhibited consistently lower microbial diversity, a reduced Bacillota/Bacteroidota ratio, and enrichment of pro-inflammatory taxa including Prevotella, Sutterella, and Bilophila. Short-chain fatty acids (SCFAs)-producing genera such as Acinetobacter, Odoribacter, Faecalibacterium, and Lachnoclostridium were depleted. Although Bilophila was identified as a third-trimester biomarker with LEfSE approach, its association with LGA disappeared after adjusting for BMI and GWG. Conversely, Nitrospirota, Polaromonas, Acinetobacter, and Aeromonas correlated negatively with LGA even after BMI and GWG adjustment. Conclusions: These findings suggest that specific maternal microbiota signatures, together with pre-pregnancy adiposity, influence fetal overgrowth in GDM and may serve as early biomarkers or targets for preventive interventions.

Escherichia coli is known to be an important uropathogenic agent. Several models were developed for investigating the uropathogensis of E. coli, including the recent biomimetic porcine urothelial in vitro model. The aim of this study was to assess the cytokine response of the cells of the biomimetic porcine urothelial model to different E. coli strains. The production of nine different cytokines in response to E. coli infection was evaluated using the commercial pre-configured immunoassay multiplex Cytokine & Chemokine 9-Plex Porcine ProcartaPlex™ Panel 1 kit. Our results showed that cells of the biomimetic porcine urothelial model reacted to the presence of all the employed different E. coli strains, albeit with some differences in levels and types of cytokines produced. Increased production of IL-10, IL-8, TNF-α, IL-1β, IL-4 and IL-12p40 was observed. Statistical analysis (Fisher’s exact test) revealed a correlation between the high fold change in the immune response and the presence of the cnf1 gene that encodes the cytotoxic necrotizing factor. Our results shed light on the cytokine response of normal urothelial cells to different E. coli strains and have the potential to fuel the search for understanding the mechanisms behind the different cytokine responses to different E. coli strains.