Identification of pili on the surface of Finegoldia magna – A Gram-positive anaerobic cocci

Anaerobes in diabetic foot infections: pathophysiology, epidemiology, virulence, and management

SUMMARYDiabetic foot infections (DFI) are a public health problem worldwide. DFI are polymicrobial, biofilm-associated infections involving complex bacterial communities organized in functional equivalent pathogroups, all including anaerobes. Indeed, multiple pathophysiological factors favor the growth of anaerobes in this context. However, the prevalence, role, and contribution of anaerobes in wound evolution remain poorly characterized due to their challenging detection. Studies based on culture reviewed herein showed a weighted average of 17% of patients with anaerobes. Comparatively, the weighted average of patients with anaerobes identified by 16S rRNA gene sequencing was 83.8%. Culture largely underestimated not only the presence but also the diversity of anaerobes compared with cultivation-independent approaches but both methods showed that anaerobic Gram-negative bacilli and Gram-positive cocci were the most commonly identified in DFI. Anaerobes were more present in deeper lesions, and their detection was associated with fever, malodorous lesions, and ulcer depth and duration. More specifically, initial abundance of Peptoniphilus spp. was associated with ulcer-impaired healing, Fusobacterium spp. detection was significantly correlated with the duration of DFI, and the presence of Bacteroides spp. was significantly associated with amputation. Antimicrobial resistance of anaerobes in DFI remains slightly studied and warrants more consideration in the context of increasing resistance of the most frequently identified anaerobes in DFI. The high rate of patients with DFI-involving anaerobes, the increased knowledge on the species identified, their virulence factors, and their potential role in wound evolution support recommendations combining debridement and antibiotic therapy effective on anaerobes in moderate and severe DFI.

Analysis of Urinary Flora Characteristics in Urinary Tumor Based on 16S rRNA Sequence

The relationship between urinary system tumors and urothelial microorganisms remains unexplored. This study is aimed at exploring the relationship between urinary flora and urinary tumors and identifying potential biomarkers for urinary tumors and new targets for prevention. We included four healthy adults (control group) and six patients diagnosed with urinary tract tumors (tumor group). In both groups, 10 and 50 ml clean middle urine samples were reserved. The 10 ml samples were analyzed (including pH, specific gravity, and leukocytes) using an automatic urine analyzer, and the 50 ml samples were analyzed by DNA extraction, 16S rRNA gene amplification, and high-throughput sequencing. The correlation between routine urine analysis and sequencing results was also analyzed. Testing using the DESeq2 method showed that, at the order level, there were significant differences in the abundance of Caulobacterales between the urinary flora of the two groups ( $P<0.05$ ); family level, Bacteroidaceae, Actinomycetaceae, and Tsukamurellaceae ( $P<0.05$ ); genus level, Finegoldia, Varibaculum, Actinobaculum, Propionimicrobium, Bacteroides, Brevundimonas, and Tsukamurella ( $P<0.05$ ). LEfSe analysis found specific bacteria at the genus level in the urinary flora of the tumor group, namely, Finegoldia (genus Digestiflora) ( $P<0.001$ ) and Varibaculum ( $P<0.001$ ). Further correlation analysis showed that both species were positively correlated with the urine pH ( $P<0.05$ ). PICRUSt analysis showed significant differences in the two functional pathways of cell transformation and metabolism ( $P<0.05$ ). Combined with the results of bioinformatics analysis, some differential bacteria may be new biomarkers for urologic tumors, and there may be a correlation between urine pH and tumor occurrence. However, large-scale prospective studies and in vitro and in vivo experiments are required to further test and verify these findings.

Peptoniphilus faecalis sp. nov., isolated from swine faeces

An obligately anaerobic, Gram-positive, non-motile, coccus-shaped bacterial strain designated AGMB00490^T was isolated from swine faeces. 16S rRNA gene sequence-based phylogenetic analysis indicated that the isolate belongs to the genus Peptoniphilus and that the most closely related species is Peptoniphilus gorbachii WAL 10418^T (=KCTC 5947^T, 97.22 % 16S rRNA gene sequence similarity). Whole genome sequence analysis determined that the DNA G+C content of strain AGMB00490^T was 31.2 mol% and moreover that the genome size and numbers of tRNA and rRNA genes were 2 129 517 bp, 34 and 10, respectively. Strain AGMB00490^T was negative for oxidase and urease; positive for catalase, indole production, arginine arylamidase, leucine arylamidase, tyrosine arylamidase and histidine arylamidase; and weakly positive for phenylalanine arylamidase and glycine arylamidase. The major cellular fatty acids (>10 %) of the isolate were determined to be C_16 : 0 and C_18 : 1 ω9c. Strain AGMB00490^T produced acetic acid as a major end product of metabolism. Accordingly, phylogenetic, physiologic and chemotaxonomic analyses revealed that strain AGMB00490^T represents a novel species for which the name Peptoniphilus faecalis sp. nov. is proposed. The type strain is AGMB00490^T (=KCTC 15944^T=NBRC 114159^T).

Analysis of Homotypic Interactions of Lactococcus lactis Pili Using Single-Cell Force Spectroscopy

Cell surface proteins of Gram-positive bacteria play crucial roles in their adhesion to abiotic and biotic surfaces. Pili are long and flexible proteinaceous filaments known to enhance bacterial initial adhesion. They promote surface colonization and are thus considered as essential factors in biofilm cohesion. Our hypothesis is that pili mediate interactions between cells and may thereby directly affect biofilm formation. In this study, we use single-cell force spectroscopy (SCFS) to quantify the force of the homotypic pili interactions between individual bacterial cells, using different Lactococcus lactis strains producing pili or not as model bacteria. Moreover the force-distance curves were analyzed to determine the physical and nanomechanical properties of L. lactis pili. The results for pili-devoided strains showed a weak adhesion between cells (adhesion forces and work in the range of 100 pN and 7 × 10^-18 J, respectively). On the contrary, the piliated strains showed high adhesion levels with adhesion forces and adhesion work over 200 pN and 50 × 10^-18 J, respectively. The force-extension curves showed multiple adhesion events, typical of the unfolding of macromolecules. These unfolding force peaks were fitted using the physical worm-like chain model to get fundamental knowledge on the pili nanomechanical properties. In addition, SCFS applied to a L. lactis isolate expressing both pili and mucus-binding protein at its surface and two derivative mutants revealed the capacity of pili to interact with other surface proteins including mucus-binding proteins. This study demonstrates that pili are involved in L. lactis homotypic interactions and thus can influence biofilm structuring.

From stem cells protection to skin microbiota balance: Orobanche rapum extract, a new natural strategy

Background

Healthy skin is a delicate balance between skin renewal and microbiota homeostasis, and its imbalance promotes premature aging and dermatological disorders. Skin stem cells are key actors in this process but their sensitivity to aging and external stressors such as UV reduces the skin renewal power. The skin microbiota has been recently described as active in the healthy skin, and its imbalance could trigger some disorders.

Aims

We hypothesized that reactivation of stem cells and maintenance of microbiota could be a disruptive strategy for younger and healthier skin. We thus developed a new plant extract that restores the entire skin renewal process by sequential activation from stem cells stimulation to microbiota protection.

Methods

We studied stem cells comportment in the presence of Orobanche rapum extract by survivin immunocytochemistry and caspases 3 and 9 dosages. We also analyzed epidermal differentiation markers by immunohistochemistry and lipids organization by GC/MS At the clinical level, we investigated the impact of O. rapum extract on microbiota and on skin aspect.

Results

We demonstrated an active protection of skin stem cells through the maintenance of their clone‐forming capacity and resistance to UV through the overexpression of survivin coupled to caspases inhibition. Furthermore, we showed the restoration of epidermal differentiation markers and ceramide biosynthesis favorable to orthorhombic organization. Clinical studies, including microbiota analysis, showed an active skin surface renewal coupled with microbiota protection.

Conclusion

We evidenced that our active ingredient is able to stimulate skin rejuvenation while protecting the cutaneous microbiota, creating healthier skin and thereby beauty.

Surfaceome and Proteosurfaceome in Parietal Monoderm Bacteria: Focus on Protein Cell-Surface Display

The cell envelope of parietal monoderm bacteria (archetypal Gram-positive bacteria) is formed of a cytoplasmic membrane (CM) and a cell wall (CW). While the CM is composed of phospholipids, the CW is composed at least of peptidoglycan (PG) covalently linked to other biopolymers, such as teichoic acids, polysaccharides, and/or polyglutamate. Considering the CW is a porous structure with low selective permeability contrary to the CM, the bacterial cell surface hugs the molecular figure of the CW components as a well of the external side of the CM. While the surfaceome corresponds to the totality of the molecules found at the bacterial cell surface, the proteinaceous complement of the surfaceome is the proteosurfaceome. Once translocated across the CM, secreted proteins can either be released in the extracellular milieu or exposed at the cell surface by associating to the CM or the CW. Following the gene ontology (GO) for cellular components, cell-surface proteins at the CM can either be integral (GO: 0031226), i.e., the integral membrane proteins, or anchored to the membrane (GO: 0046658), i.e., the lipoproteins. At the CW (GO: 0009275), cell-surface proteins can be covalently bound, i.e., the LPXTG-proteins, or bound through weak interactions to the PG or wall polysaccharides, i.e., the cell wall binding proteins. Besides monopolypeptides, some proteins can associate to each other to form supramolecular protein structures of high molecular weight, namely the S-layer, pili, flagella, and cellulosomes. After reviewing the cell envelope components and the different molecular mechanisms involved in protein attachment to the cell envelope, perspectives in investigating the proteosurfaceome in parietal monoderm bacteria are further discussed.

Pan-genome analysis of the genus Finegoldia identifies two distinct clades, strain-specific heterogeneity, and putative virulence factors

Finegoldia magna, a Gram-positive anaerobic coccus, is an opportunistic pathogen, associated with medical device-related infections. F. magna is the only described species of the genus Finegoldia. We report the analysis of 17 genomes of Finegoldia isolates. Phylogenomic analyses showed that the Finegoldia population can be divided into two distinct clades, with an average nucleotide identity of 90.7%. One clade contains strains of F. magna, whereas the other clade includes more heterogeneous strains, hereafter tentatively named "Finegoldia nericia". The latter species appears to be more abundant in the human microbiome. Surface structure differences between strains of F. magna and "F. nericia" were detected by microscopy. Strain-specific heterogeneity is high and previously identified host-interacting factors are present only in subsets of "F. nericia" and F. magna strains. However, all genomes encode multiple host factor-binding proteins such as albumin-, collagen-, and immunoglobulin-binding proteins, and two to four copies of CAMP (Christie-Atkins-Munch-Petersen) factors; in accordance, most strains show a positive CAMP reaction for co-hemolysis. Our work sheds new light of the genus Finegoldia and its ability to bind host components. Future research should explore if the genomic differences identified here affect the potential of different Finegoldia species and strains to cause opportunistic infections.

Finegoldia magna Isolated from Orthopedic Joint Implant-Associated Infections

The anaerobic Gram-positive coccus Finegoldia magna is a rare cause of infections of bone and joints. The aim of this study was to describe the microbiological and clinical characteristics of orthopedic implant-associated infections caused by F. magna We retrospectively analyzed samples consisting of anaerobic Gram-positive cocci and samples already identified as F. magna from patients with orthopedic infections. The isolates found were determined to the species level using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The antibiotic susceptibility pattern was determined by Etest. Whole-genome sequencing (WGS) was performed. Clinical data were extracted from each patient's journal. In nine patients, orthopedic joint implant-associated infections were identified as being caused by F. magna The isolates were susceptible to most of the antibiotics tested, with the exception of rifampin and moxifloxacin in a few cases. Five of the nine infections were monomicrobial. The most common antibiotic used to treat the infection was penicillin V, but five of the nine patients received a combination of antibiotics. Eight patients underwent surgical treatment, with extraction of the implant performed in seven cases and reimplantation in only two cases. The WGS showed a relatively small core genome, with 126,647 single nucleotide polymorphisms identified within the core genome. A phylogenomic analysis revealed that the isolates clustered into two distinct clades. Orthopedic implant-associated infections caused by F. magna are rare, but the bacteria are generally susceptible to antibiotics. Despite this, surgical treatment combined with long-term antibiotics is often necessary. The WGS analysis revealed a high heterogeneity and suggested the existence of at least two different Finegoldia species.

Sonication culture improves microbiological diagnosis of modular megaprostheses

Modular megaprostheses are known for high infection rates followed by high rates of revisions. Microbial biofilms growing adherently on prosthetic surfaces may inhibit the detection of the pathogens causing prosthetic joint infections. We sought to answer the following questions: Does sonication culture (SC) improve the microbiological diagnosis of periprosthetic infections of megaprostheses compared to conventional tissue culture (TC)? Which pathogens were detected on the surface of megaprostheses with either SC or TC and do the findings help to identify low-grade infections? Included were 31 patients with modular megaprostheses, whose implant had been explanted due to suspected joint infection or revision surgery. SCs were performed according to the protocol by Trampuz et al. The diagnosis of infection was evaluated according to the definition of the Musculoskeletal Infection Society. The sensitivity of SC was 91.3% compared to 52.2% for TC and the specificity was 100% for SC and TC (p = 0.004). Under preoperative antibiotic therapy, the sensitivity of SC was 83.3% while the sensitivity of TC was 50%. Without preoperative antibiotic therapy the sensitivity of SC was 100% compared to 54.5% for TC. In nine cases, SCs detected microorganisms, while TC was negative. Detected bacteria were Staphylococcus epidermidis in four, Micrococcus species in one, Finegoldia magna in one, Brevibacterium casei in one, Pseudomonas fluorescens in one, and Enterococcus faecium in one. SC is a reliable method for dislodging pathogens from orthopedic implants. The SC of modular megaprostheses showed significantly higher pathogen detection than the periprosthetic TC, especially for low virulence pathogens. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1383-1387, 2017.