This study assessed the clonal diversity, the resistance profile and the virulence potential of Escherichia coli strains isolated from diabetic foot infection (DFI) and diabetic foot osteomyelitis (DFOM). A retrospective single-centre study was conducted on patients diagnosed with E. coli isolated from deep DFI and DFOM at Clinique du Pied Diabétique Gard-Occitanie (France) over a two-year period. Phylogenetic backgrounds, virulence factors (VFs) and antibiotic resistance profiles were determined. Whole-genome analysis of E. coli strains isolated from same patients at different periods were performed. From the two-years study period, 35 E. coli strains isolated from 33 patients were analysed; 73% were isolated from DFOM. The majority of the strains belonged to the virulent B2 and D phylogenetic groups (82%). These isolates exhibited a significant higher average of VFs number than strains belonging to other groups (p < 0.001). papG2 gene was significantly more detected in strains belonging to B2 phylogroup isolated from DFI compared to DFOM (p = 0.003). The most prevalent antibiotic resistance pattern was observed for ampicillin (82%), cotrimoxazole (45%), and ciprofloxacin (33%). The genome analysis of strains isolated at two periods in DFOM showed a decrease of the genome size, and this decrease was more important for the strain isolated at nine months (vs. four months). A shared mutation on the putative acyl-CoA dehydrogenase-encoding gene aidB was observed on both strains. E. coli isolates from DFOM were highly genetically diverse with different pathogenicity traits. Their adaptation in the bone structure could require genome reduction and some important modifications in the balance virulence/resistance of the bacteria.

Necrotizing enterocolitis (NEC) remains a leading cause of morbidity and mortality, affecting primarily preterm neonates. The pathogenesis of this intestinal disease appears to be linked to the disruption or delay of bacterial colonization, termed gut dysbiosis. Intestinal immaturity, antibiotic use and hospital microbial environment are the main triggers of this pathological process. Conversely, gut symbiosis is made possible by the presence of beneficial and commensal bacterial species that protect the immature gut from opportunistic pathogens overgrowth and inflammation. Herein, we review the relationships between gut microbiota and NEC in preterm neonates. We also discuss the role of specific microorganisms belonging to the commensal microbiota, highlighting the possibility for a toxigenic mechanism involved in NEC pathogenesis. We conclude on the importance of interventions aimed at providing or restoring beneficial bacteria populations, in view to efficiently preventing or treating NEC. Keywords: Necrotizing enterocolitis, Gut microbiota, Dysbiosis, Toxin

The association between Clostridium species identification from stool samples in preterm neonates and the occurrence of necrotizing enterocolitis has been increasingly reported. To confirm the specific impact of Clostridium butyricum in this pathology, selective culture procedure was used for Clostridia isolation. Whole-genome analysis was employed to investigate genomic relationships between isolates. Stool samples from present study, as well as from previously investigated cases, were implicated including 88 from preterm neonates with necrotizing enterocolitis and 71 from matched controls. Quantitative real-time polymerase chain reaction was performed to evaluate the presence of C. butyricum from stools of new cases. Clostridium species prevalence isolated by culture was compared between patients with necrotizing enterocolitis and controls. By combining results of both culture and quantitative polymerase chain reaction methods, C. butyricum was significantly more frequent in stool samples from preterm neonates with necrotizing enterocolitis than in controls. Whole-genome analysis of 81 genomes including 58 neonates’ isolates revealed that cases were clustered depending on geographical origin of isolation. Controls isolates presented genomic relations with that of patients suggesting a mechanism of asymptomatic carriage. Overall, this suggests an epidemiology comparable to that observed in Clostridium difficile colitis in adults.

Clostridium phoceensis sp. nov., strain GD3T (= CSUR P1929 = DSM 100334) is the type strain of C. phoceensis sp. nov., a new species within the genus Clostridium. This strain was isolated from the gut microbiota of a 28-year-old healthy French man. C. phoceensis is a Gram-negative, spore-forming, nonmotile, strictly anaerobic bacterium. We describe its complete genome sequence and annotation, together with its phenotypic characteristics.

Clostridia-especially Clostridium butyricum-are among the taxa most frequently identified from stool samples of preterm neonates with necrotizing enterocolitis (NEC). Recently, Clostridium neonatale has also been detected from epidemic cases, but using a culture-based approach we were unable to confirm this discovery in a local cohort. In order to investigate this link by a molecular approach, a specific rpoB-based quantitative real-time PCR was developed to detect C. neonatale directly from patients' stool specimens. Design of this rpoB-based quantitative real-time PCR was based on the genomic analysis of seven clinical isolates of C. neonatale. It was tested on stool samples from 88 preterm neonates with necrotizing enterocolitis and 71 matched controls. C. neonatale was significantly more prevalent in stools from preterm neonates with necrotizing enterocolitis than in controls (respectively 30/88 (34%) versus 9/71 (13%); p 0.003). Whole-genome analysis also allowed the identification of three genomic clusters of C. neonatale. This clustering was associated with a geographical location regardless of isolation from the NEC or control, suggesting asymptomatic carriage. Although less prevalent than C. butyricum in our cohort, C. neonatale is significantly associated with the occurrence of necrotizing enterocolitis.

We report the main characteristics of "Lachnoclostridium bouchesdurhonense" strain AT5(T) (=CSUR P2181), a new bacterial species isolated from the gut microbiota of an obese patient from Marseille.