Staphylococcus aureus adheres to human intestinal mucus but can be displaced by certain lactic acid bacteria

Complete Genome Sequence and Probiotic Properties of Pediococcus acidilactici CLP03 Isolated from Healthy Felis catus

Probiotics are available from various sources, including the gastrointestinal tract of healthy animals. In this study, Pediococcus acidilactici was isolated for the first time from Felis catus and evaluated for its functionality. The findings revealed that P. acidilactici CLP03 exhibited inhibitory properties against pathogenic bacteria (E. coli, Salmonella, S. aureus, P. aeruginosa, and L. monocytogenes). Then, survival of strains exposed to pH 2.5, 0.3% bile salts, 0.5% bile salts, and gastrointestinal fluids was 63.97%, 98.84%, 87.95%, and 52.45%, respectively. Also, P. acidilactici CLP03 demonstrated high hydrophobicity (69.63-82.03%) and self-aggregation (73.51-81.44%), negative for hemolytic, and was susceptible to clindamycin. Finally, the scavenging rates of DPPH, ABTS, and O2- were 53.55%, 54.81%, and 85.13%, respectively, which demonstrated that the strain CLP03 has good oxidation resistance. All these characteristics contribute to the survival, colonization, and functionality of the strain in the gastrointestinal tract, indicating their excellent probiotic potential. On the other hand, animal experiments (KM mice, randomly assigned to four groups) showed that the gavage of CLP03 had no toxic effects on mice, increased the serum SOD content, and decreased the MDA and BUN contents, which revealed gavage of CLP03 significantly increased the antioxidant capacity of mice in vivo. In addition, complete genome annotation showed that P. acidilactici CLP03 had 1976 CDS genes, and the numbers of CRISPR, gene islands, and phages were 8, 3, and 6, respectively. In conclusion, P. acidilactici CLP03 could be a candidate functional cat probiotic to enhance animal health and welfare.

Pathogen exclusion from intestinal mucus and antimicrobial susceptibility of Bifidobacterium spp. strains from fecal donors

Aim: To study the ability of bifidobacterial strains isolated from fecal donors to prevent pathogens from adhering to intestinal mucus, along with their antimicrobial susceptibility. Methods: Pathogen prevention was assessed through an in vitro adhesion assay using immobilized porcine mucus. Subsequently, bifidobacterial RNA-Seq data were analyzed to pinpoint glycoside hydrolases and glycosyltransferases possibly involved in mucus degradation affecting pathogen adhesion. The antimicrobial susceptibility of bifidobacterial strains was evaluated using in vitro susceptibility testing, followed by analysis of whole-genome sequencing data to reveal antimicrobial resistance genes. Results: Bifidobacterial strains inhibited pathogen adhesion to intestinal mucus, with most strains reducing the adhesion levels of pathogens like Escherichia coli, Listeria monocytogenes, Salmonella Typhimurium, and Staphylococcus aureus by at least 70%. None of the strains significantly affected Pseudomonas aeruginosa, but they moderately reduced the adhesion of Yersinia enterocolitica. Gene expression analysis indicated that the more effective strains expressed higher levels of glycoside hydrolases, correlating with their pathogen exclusion capabilities. Antimicrobial susceptibility testing revealed that most strains were sensitive to several antibiotics, though some exhibited resistance to tobramycin, trimethoprim, and ciprofloxacin. Notably, one strain carried the tetW gene, conferring resistance to tetracycline. Conclusion: The bifidobacterial strains characterized in this study show potential for bacteriotherapeutic applications due to their strong ability to interfere with the adhesion of pathogenic bacteria and their lack of alarming antimicrobial resistance patterns.

Staphylococcus aureus Infections and Human Intestinal Microbiota

Staphylococcus aureus (S. aureus) is a common pathogen that can cause many human diseases, such as skin infection, food poisoning, endocarditis, and sepsis. These diseases can be minor infections or life-threatening, requiring complex medical management resulting in substantial healthcare costs. Meanwhile, as the critically ignored "organ," the intestinal microbiome greatly impacts physiological health, not only in gastrointestinal diseases but also in disorders beyond the gut. However, the correlation between S. aureus infection and intestinal microbial homeostasis is largely unknown. Here, we summarized the recent progress in understanding S. aureus infections and their interactions with the microbiome in the intestine. These summarizations will help us understand the mechanisms behind these infections and crosstalk and the challenges we are facing now, which could contribute to preventing S. aureus infections, effective treatment investigation, and vaccine development.

Propionibacteria as promising tools for the production of pro-bioactive scotta: a proof-of-concept study

Dairy propionibacteria are Gram positive Actinomycetota, routinely utilized as starters in Swiss type cheese making and highly appreciated for their probiotic properties and health promoting effects. In this work, within the frame of a circular economy approach, 47 Propionibacterium and Acidipropionibacterium spp. were isolated from goat cheese and milk, and ewe rumen liquor, and characterized in view of their possible utilization for the production of novel pro-bioactive food and feed on scotta, a lactose rich substrate and one of the main by-products of the dairy industry. The evaluation of the Minimum Inhibitory Concentration (MIC) of 13 among the most common antibiotics in clinical practice revealed a general susceptibility to ampicillin, gentamycin, streptomycin, vancomycin, chloramphenicol, and clindamycin while confirming a lower susceptibility to aminoglycosides and ciprofloxacin. Twenty-five isolates, that proved capable of lactose utilization as the sole carbon source, were then characterized for functional and biotechnological properties. Four of them, ascribed to Propionibacterium freudenreichii species, and harboring resistance to bile salts (growth at 0.7-1.56 mM of unconjugated bile salts), acid stress (>80% survival after 1 h at pH 2), osmostress (growth at up to 6.5% NaCl) and lyophilization (survival rate > 80%), were selected and inoculated in scotta. On this substrate the four isolates reached cell densities ranging from 8.11 ± 0.14 to 9.45 ± 0.06 Log CFU mL-1 and proved capable of producing different vitamin B9 vitamers after 72 h incubation at 30°C. In addition, the semi-quantitative analysis following the metabolomics profiling revealed a total production of cobalamin derivatives (vitamin B12) in the range 0.49-1.31 mg L-1, thus suggesting a full activity of the corresponding biosynthetic pathways, likely involving a complex interplay between folate cycle and methylation cycle required in vitamin B12 biosynthesis. These isolates appear interesting candidates for further ad-hoc investigation regarding the production of pro-bioactive scotta.

Probiotic characteristics and whole-genome sequence analysis of Pediococcus acidilactici isolated from the feces of adult beagles

The beneficial effects of lactic acid bacteria are well known and recognized as functional foods that are health benefits for companion animals. This study, for the first time, reports the probiotic properties, safety, and whole-genome sequence of Pediococcus acidilactici GLP06 isolated from feces of beagles. In this study, candidate probiotic bacteria P. acidilactici GLP02 and GLP06 were morphologically characterized and tested for their antimicrobial capacity, tolerance to different conditions (low pH, bile salts, an artificial gastrointestinal model, and high temperature), antibiotic sensitivity, hemolytic activity, cell surface hydrophobicity, autoaggregation activity, and adhesion to Caco-2 cells. P. acidilactici GLP06 showed better probiotic potential. Therefore, P. acidilactici GLP06 was evaluated for in vivo safety in mice and whole-genome sequencing. The results showed, that the supplemented MG06 group (1010 cfu/mL), GLP06 was not only nontoxic to mice, but also promoted the development of the immune system, improved resistance to oxidative stress, and increased the diversity of intestinal microorganisms and the abundance of Lactobacillus. Whole-genome sequencing showed that P. acidilactici GLP06 was 2,014,515 bp and contained 1,976 coding sequences, accounting for 86.12% of the genome, with no drug resistance genes and eight CRISPR sequences. In conclusion, the newly isolated canine-derived P. acidilactici GLP06 had good probiotic potential, was nontoxic to mice and promoted the development of immune organs, improved the biodiversity of the intestinal flora, and had no risk of drug-resistant gene transfer, indicating that P. acidilactici GLP06 can be used as a potential probiotic for the prevention and treatment of gastrointestinal diseases in companion animals.

The Microbiota and the Relationship with Colorectal Cancer: Surgical Complications—A Review

Colorectal cancer (CRC) is one of the most common cancers and represents a major global health burden. While genetics are implicated in a portion of CRC patients, most cases are sporadic. A new possibility of tumor initiation and promotion might be microbiome composition. It was recently shown that bacteria from the gut microbiome might be used as biomarkers for CRC detection, especially Fusobacterium nucleatum, Peptostreoptococcus stomatis, Parvimonas mica, Solobacterium moorei, and Peptostreptococcus anaerobius. Conversely, the healthy gut microbiome is mostly colonized by Bacterioides (Bacterioides fragilis, vulgatus, uniformis), Firmicutes (Clostridium spp., Ruminococcus faecis, Enterococcus faecium), and Actinobacteria (Bifidobacterium bifidum). Some strains of gut bacteria favor tumor promotion through DNA and RNA damage (directly or through interaction with other known food carcinogens) and through local immune inhibition. It is possible that bacteria (e.g., Bacillus polyfermenticus, Alistipes shahii, Lactobacillus casei) exist with protective functions against tumor promotion. Despite current advances in colorectal cancer treatment, especially in the medical oncology and radiotherapy domains, surgery remains the mainstay of curative treatment for colorectal cancer patients, even in the oligometastatic setting. Surgical complications like anastomotic leakage, excessive blood loss, abscess, and abdominal sepsis can reduce 1-year and 5-year overall survival and increase the recurrence rates for these patients; therefore, we reviewed currently published data focusing on the relationship between gut microbiota and postoperative complications for colorectal cancer patients.

Lacticaseibacillus rhamnosus: A Suitable Candidate for the Construction of Novel Bioengineered Probiotic Strains for Targeted Pathogen Control

Probiotics, with their associated beneficial effects, have gained popularity for the control of foodborne pathogens. Various sources are explored with the intent to isolate novel robust probiotic strains with a broad range of health benefits due to, among other mechanisms, the production of an array of antimicrobial compounds. One of the shortcomings of these wild-type probiotics is their non-specificity. A pursuit to circumvent this limitation led to the advent of the field of pathobiotechnology. In this discipline, specific pathogen gene(s) are cloned and expressed into a given probiotic to yield a novel pathogen-specific strain. The resultant recombinant probiotic strain will exhibit enhanced species-specific inhibition of the pathogen and its associated infection. Such probiotics are also used as vehicles to deliver therapeutic agents. As fascinating as this approach is, coupled with the availability of numerous probiotics, it brings a challenge with regard to deciding which of the probiotics to use. Nonetheless, it is indisputable that an ideal candidate must fulfil the probiotic selection criteria. This review aims to show how Lacticaseibacillus rhamnosus, a clinically best-studied probiotic, presents as such a candidate. The objective is to spark researchers’ interest to conduct further probiotic-engineering studies using L. rhamnosus, with prospects for the successful development of novel probiotic strains with enhanced beneficial attributes.

Compound Probiotics Improve the Diarrhea Rate and Intestinal Microbiota of Newborn Calves

Simple Summary

Calf diarrhea is a major cause of mortality in calves, and results in high treatment costs and economic loss for the dairy and cattle industries. In addition, diarrhea usually occurs around 2 weeks after calf birth. In this study, we determined how compound probiotics influenced the gut microbiota and its effect on diarrhea rates of newborn Holstein calves. The probiotics included compound yeast (Saccharomyces cerevisiae and Kluyveromyces marxianus) and lactic acid bacteria (Lactococcus lactis subsp. lactis, Pediococcus pentosaceus, and Lactobacillus plantarum). Among them, the LS, L, and S groups are different compound probiotic groups, and the D group is the control group. Our results revealed that although probiotics did not affect the community diversity of gut bacteria in newborn calves, compound probiotics significantly increased the community richness of gut bacteria. Principal coordinates analysis using weighted UniFrac distances showed that the microbial communities of calves fed compound probiotics were relatively closely clustered, but were separate from the communities of calves in the control group. The calves fed compound probiotics also had lower rates of diarrhea. Our findings improve our understanding of the role of probiotics in regulating the gut microbiota of calves, and are of special significance to researchers in the dairy and cattle industries.

Abstract

We evaluated the effects of probiotic compounds on the composition of the gut microbiota. Forty newborn calves were random allocated to the lactic acid bacteria + yeast group (LS group), lactic acid bacteria group (L group), yeast group (S group), and control group (D group). Probiotics containing Lactococcus lactis subsp. lactis, Pediococcus pentosaceus, Lactobacillus plantarum, Saccharomyces cerevisiae, and Kluyveromyces marxianus were fed to calves in the three treatment groups for 15 days. The feeding process lasted 15 days. Fecal samples were collected from all calves at the end of the trial and analyzed using high-throughput 16S rRNA sequencing. Totals of 1,029,260 high-quality reads and 420,010,128 bp of sequences were obtained. Among the four groups, the alpha diversity of gut microbes was significantly higher in newborn cattle in the LS group than in those in the L, S, and D groups. Overall, the dominant phyla were Firmicutes, Actinobacteria, and Bacteroidetes, whereas Bifidobacterium was the most abundant phylum in the gut of cattle in the LS group. Newborn calves from the compound probiotic groups had closely clustered gut bacterial communities and had lower rates of diarrhea. Overall, compound probiotics regulated the intestinal microbiota community structure of newborn calves and improved intestinal health. New information relevant to the prevention of diarrhea is provided by our research in newborn calves.

Effects of Lactic Acid Bacteria Isolated from Equine on Salmonella-Infected Gut Mouse Model

The aim of this study was to evaluate the antibacterial potential of lactic acid bacteria (Weissella confuse, Pediococcus acidilactici, and Ligilactobacillus equi) isolated from healthy equine in Wuhan against Salmonella Typhimurium CVCC542-induced mice model on intestinal microflora. In previous studies, these isolated strains showed good probiotic potentials in vitro. In this study, fifty healthy mice were randomly divided into five groups, the blank control group, the control group, the Pediococcus acidilactici group (1 × 10⁸ CFU/day), the Ligilactobacillus equi group (1 × 10⁸ CFU/day), and the Weissella confuse group (1 × 10⁸ CFU/day). The body weight in control group and Weissella confuse group showed significant decreased (P < 0.05, P < 0.01), while Pediococcus acidilactici group and Ligilactobacillus equi group showed good recovering after treatments. The lowest diarrhea rate was shown in Ligilactobacillus equi group after treatment. In histopathology, Ligilactobacillus equi group showed the least structural damage in duodenum, and all probiotic treatment groups showed less damage in cecum. The sequence data and optical transform unit showed that Pediococcus acidilactici group and Ligilactobacillus equi group had higher number than control group, while the diversity data showed that the control group and Weissella confuse group had lower diversity in cecum. Microbial community analysis showed increased abundance of Firmicutes, Bacteroidetes, uncultured_bacterium_f_Muribaculaceae, and Lactobacillus in treatment groups, while potential microbes that can induce intestinal diseases such as Verrucomicrobia, Akkermansia, and Lachnospiraceae_NK4A136_group decreased in the treatment groups. In conclusion, lactic acid bacteria isolated from the healthy horses could alleviate the infection of Salmonella and regulate intestinal flora.

Staphylococcal trafficking and infection - from 'nose to gut' and back

Staphylococcus aureus is an opportunistic human pathogen, which is a leading cause of infections worldwide. The challenge in treating S. aureus infection is linked to the development of multidrug-resistant strains and the mechanisms employed by this pathogen to evade the human immune defenses. In addition, S. aureus can hide asymptomatically in particular ‘protective’ niches of the human body for prolonged periods of time. In the present review, we highlight recently gained insights in the role of the human gut as an endogenous S. aureus reservoir next to the nasopharynx and oral cavity. In addition, we address the contribution of these ecological niches to staphylococcal transmission, including the roles of particular triggers as modulators of the bacterial dissemination. In this context, we present recent advances concerning the interactions between S. aureus and immune cells to understand their possible roles as vehicles of dissemination from the gut to other body sites. Lastly, we discuss the factors that contribute to the switch from colonization to infection. Altogether, we conclude that an important key to uncovering the pathogenesis of S. aureus infection lies hidden in the endogenous staphylococcal reservoirs, the trafficking of this bacterium through the human body and the subsequent immune responses.

The TGF-β ligand DBL-1 is a key player in a multifaceted probiotic protection against MRSA in C. elegans

Worldwide the increase in multi-resistant bacteria due to misuse of traditional antibiotics is a growing threat for our health. Finding alternatives to traditional antibiotics is thus timely. Probiotic bacteria have numerous beneficial effects and could offer safer alternatives to traditional antibiotics. Here, we use the nematode Caenorhabditis elegans (C. elegans) to screen a library of different lactobacilli to identify potential probiotic bacteria and characterize their mechanisms of action. We show that pretreatment with the Lactobacillus spp. Lb21 increases lifespan of C. elegans and results in resistance towards pathogenic methicillin-resistant Staphylococcus aureus (MRSA). Using genetic analysis, we find that Lb21-mediated MRSA resistance is dependent on the DBL-1 ligand of the TGF-β signaling pathway in C. elegans. This response is evolutionarily conserved as we find that Lb21 also induces the TGF-β pathway in porcine epithelial cells. We further characterize the host responses in an unbiased proteome analysis and identify 474 proteins regulated in worms fed Lb21 compared to control food. These include fatty acid CoA synthetase ACS-22, aspartic protease ASP-6 and vitellogenin VIT-2 which are important for Lb21-mediated MRSA resistance. Thus, Lb21 exerts its probiotic effect on C. elegans in a multifactorial manner. In summary, our study establishes a mechanistic basis for the antimicrobial potential of lactobacilli.

Silicon-containing water intake confers antioxidant effect, gastrointestinal protection, and gut microbiota modulation in the rodents

We explored the effects of silicon-containing water (BT) intake on gastrointestinal function and gut microbiota. BT was obtained by pressuring tap water through silicon minerals (mullite, Al₆Si₂O₁₃) column. BT decreased H₂O₂ chemiluminescence counts, indicating its antioxidant activity. Four weeks of BT drinking increased H₂O₂ scavenging activity and glutathione peroxidase activity of plasma. BT drinking did not affect the body weight but significantly reduced the weight of feces and gastrointestinal motility. BT drinking significantly suppressed pylorus ligation enhanced gastric juice secretion, gastric reactive oxygen species amount, erythrocyte extravasation, IL-1β production by infiltrating leukocyte, and lipid peroxidation within gastric mucosa. Data from 16S rRNA sequencing revealed BT drinking significantly increased beneficial flora including Ruminococcaceae UCG-005, Prevotellaceae NK3B31, Weissella paramesenteroides, Lactobacillus reuteri, and Lactobacillus murinus and decreased harmful flora including Mucispirillum, Rodentibacter, and Staphylococcus aureus. This study pioneerly provided scientific evidences for the potential effects of water-soluble forms of silicon intake on antioxidant activity, gastrointestinal function, and gut microbiota modulation.

Novel Odoribacter splanchnicus Strain and Its Outer Membrane Vesicles Exert Immunoregulatory Effects in vitro

Odoribacter splanchnicus, belonging to the order Bacteroidales, is a common, short-chain fatty acid producing member of the human intestinal microbiota. A decreased abundance of Odoribacter has been linked to different microbiota-associated diseases, such as non-alcoholic fatty liver disease, cystic fibrosis and inflammatory bowel disease (IBD). The type strain of O. splanchnicus has been genome-sequenced, but otherwise very little is known about this anaerobic bacterium. The species surfaces in many microbiota studies and, consequently, comprehension on its interactions with the host is needed. In this study, we isolated a novel strain of O. splanchnicus from a healthy fecal donor, identified it by genome sequencing and addressed its adhesive, epithelium reinforcing and immunoregulatory properties. Our results show that O. splanchnicus strain 57 is non-adherent to enterocytes or mucus, does not reinforce nor compromise Caco-2 monolayer integrity and most likely harbors penta-acylated, less endotoxic lipid A as part of its lipopolysaccharide (LPS) structure based on the lack of gene lpxM and in vitro results on low-level NF-κB activity. The studies by transmission electron microscopy revealed that O. splanchnicus produces outer membrane vesicles (OMV). O. splanchnicus cells, culture supernatant i.e., spent medium or OMVs did not induce interleukin-8 (IL-8) response in HT-29 enterocyte cells suggesting a very low proinflammatory capacity. On the contrary, the treatment of HT-29 cells with O. splanchnicus cells, spent medium or OMVs prior to exposure to Escherichia coli LPS elicited a significant decrease in IL-8 production as compared to E. coli LPS treatment alone. Moreover, O. splanchnicus spent supernatant induced IL-10 production by immune cells, suggesting anti-inflammatory activity. Our in vitro findings indicate that O. splanchnicus and its effector molecules transported in OMVs could potentially exert anti-inflammatory action in the gut epithelium. Taken together, O. splanchnicus seems to be a commensal with a primarily beneficial interaction with the host.

Adhesion of Staphylococcus aureus to epithelial cells: an in vitro approach to study interactions within the nasal microbiota

Introduction. Staphylococcus aureus is a skin and mucous commensal bacterium of warm-blooded animals. In humans, the nose is the main ecological niche of S. aureus, and nasal carriage is a risk factor for developing an endogenous infection. S. aureus nasal colonization is a multifactorial process, involving inter-species interactions among the nasal microbiota.Aims. The objectives of this study were to characterize the microbiota of carriers and non-carriers of S. aureus and to demonstrate the importance of inter-species relationships in the adhesion of S. aureus, a key step in nasal colonization.Methodology. First, we characterized the nasal microbiota from 30 S. aureus carriers and non-carriers by a culturomic approach. We then evaluated the adhesion of S. aureus, first alone and then along with other bacteria of the nasal microbiota. To do that, we used an in vitro model to measure the interactions among bacteria in the presence of epithelial cells.Results. Analysis of the nasal microbiota of the carriers and non-carriers of S. aureus made it possible to observe that each microbiota has specific features in terms of composition. However, this composition differs significantly between carriers and non-carriers mainly through two bacterial groups: coagulase-negative staphylococci and corynebacteria. In a second part, adhesion of S. aureus to epithelial cells showed competition between S. aureus and these bacteria, suggesting a limitation of nasal colonization by S. aureus.Conclusion. These findings demonstrate the existence of a negative correlation between S. aureus and other species which inhibits adhesion and could limit nasal colonization.

A Review of Current Knowledge on Staphylococcus agnetis in Poultry

Simple Summary

This literature review provides a synthesis and evaluation of the current knowledge on Staphylococcus agnetis (S. agnetis) and its implications in poultry pathology. Recent studies revealed that S. agnetis can cause bacterial chondronecrosis with osteomyelitis (BCO), endocarditis, and septicemia in broiler chickens. Lameness constitutes one of the major health and welfare problems causing huge economic losses in the poultry industry. To date, a range of infectious and non-infectious factors have been associated with lameness in poultry. Among bacteria of the genus Staphylococcus, Staphylococcus aureus is the main species associated with locomotor problems. This contrasts with S. agnetis, which until recently had not been considered as a poultry pathogen. Previously only reported in cattle, S. agnetis has expanded its host range to chickens, and due to its unique characteristics has become recognized as a new emerging pathogen. The genotypic and phenotypic similarities between S. agnetis and other two staphylococci (S. hyicus and S. chromogenes) make this pathogen capable of escaping recognition due to misidentification. Although a significant amount of research on S. agnetis has been conducted, many facts about this novel species are still unknown and further studies are required to understand its full significance in poultry pathology.

Abstract

This review aims to summarize recent discoveries and advancements regarding the characteristics of Staphylococcus agnetis (S. agnetis) and its role in poultry pathology. S. agnetis is an emerging pathogen that was primarily associated with mastitis in dairy cattle. After a presumed host jump from cattle to poultry, it was identified as a pathological agent in broiler chickens (Gallus gallus domesticus), causing lameness induced by bacterial chondronecrosis with osteomyelitis (BCO), septicemia, and valvular endocarditis. Economic and welfare losses caused by lameness are global problems in the poultry industry, and S. agnetis has been shown to have a potential to induce high incidences of lameness in broiler chickens. S. agnetis exhibits a distinct repertoire of virulence factors found in many different staphylococci. It is closely related to S. hyicus and S. chromogenes, hence infections caused by S. agnetis may be misdiagnosed or even undiagnosed. As there are very few reports on S. agnetis in poultry, many facts about its pathogenesis, epidemiology, routes of transmission, and the potential impacts on the poultry industry remain unknown.

The Effectiveness of Multi-Session FMT Treatment in Active Ulcerative Colitis Patients: A Pilot Study

The modification of the microbiome through fecal microbiota transplantation (FMT) is becoming a very promising therapeutic option for inflammatory bowel disease (IBD) patients. Our pilot study aimed to assess the effectiveness of multi-session FMT treatment in active ulcerative colitis (UC) patients. Ten patients with UC were treated with multi-session FMT (200 mL) from healthy donors, via colonoscopy/gastroscopy. Patients were evaluated as follows: at baseline, at week 7, and after 6 months, routine blood tests (including C reactive protein (CRP) and calprotectin) were performed. 16S rRNA gene (V3V4) sequencing was used for metagenomic analysis. The severity of UC was classified based on the Truelove–Witts index. The assessment of microbial diversity showed significant differences between recipients and healthy donors. FMT contributed to long-term, significant clinical and biochemical improvement. Metagenomic analysis revealed an increase in the amount of Lactobacillaceaea, Micrococcaceae, Prevotellaceae, and TM7 phylumsp.oral clone EW055 during FMT, whereas Staphylococcaceae and Bacillaceae declined significantly. A positive increase in the proportion of the genera Bifidobacterium, Lactobacillus, Rothia, Streptococcus, and Veillonella and a decrease in Bacillus, Bacteroides, and Staphylococcus were observed based on the correlation between calprotectin and Bacillus and Staphylococcus; ferritin and Lactobacillus, Veillonella, and Bifidobacterium abundance was indicated. A positive change in the abundance of Firmicutes was observed during FMT and after 6 months. The application of multi-session FMT led to the restoration of recipients’ microbiota and resulted in the remission of patients with active UC.

Functional probiotics of lactic acid bacteria from Hu sheep milk

Background

Probiotics are being considered as valuable microorganisms related to human health. Hu sheep is referred as one of the important sheep breeds in China. Goat milk produced by Hu sheep is characterized with high nutritional value and hypoallergenic in nature. Particularly, this milk contains plenty of milk prebiotic and probiotic bacteria. This study was aimed to scrutinize more bacterial strains from Hu sheep milk with potential probiotic activity.

Results

Based on 16S rRNA sequence analysis, pool of forty bacterial strains were identified and evaluated their antimicrobial activities against Staphylococcus aureus, enterohemorrhagic Escherichia coli (EHEC), Salmonella typhimurium, Listeria monocytogenes enterotoxigenic E. coli (ETEC) and Aeromonas caviae. Four out of these isolated strains demonstrated their efficient bacteriostatic ability and potential healthy properties. We also examined the safety aspects of these bacterial candidates including three Lactococcus lactis strains (named as HSM-1, HSM-10, and HSM-18) and one Leuconostoc lactis strain (HSM-14), and were further evaluated via in vitro tests, including antimicrobial activity, cell surface characteristics (hydrophobicity, co-aggregation, and self-aggregation), heat treatment, antibiotic susceptibility, simulated transport tolerance in the gastrointestinal tract, and acid/bile tolerance. The obtained results revealed that HSM-1, HSM-10, HSM-14, and HSM-18 showed high survival rate at different conditions for example low pH, presence of bovine bile and demonstrated high hydrophobicity. Moreover, HSM-14 had an advantage over other strains in terms of gastrointestinal tract tolerance, antimicrobial activities against pathogens, and these results were significantly better than other bacterial candidates.

Conclusion

Hu sheep milk as a source of exploration of potential lactic acid bacteria (LAB) probiotics open the new horizon of probiotics usage from unconventional milk sources. The selected LAB strains are excellent probiotic candidates which can be used for animal husbandry in the future. Rationale of the study was to utilize Hu sheep milk as a source of potential probiotic LABs. The study has contributed to the establishment of a complete bacterial resource pool by exploring the Hu sheep milk microflora.

Staphylococcal infections and infertility: mechanisms and management

Infertility is a subject of worldwide concern as it affects approximately 15% of couples. Among the prime contributors of infertility, urogenital bacterial infections have lately gained much clinical importance. Staphylococcal species are commensal bacteria and major human pathogens mediating an array of reproductive tract infections. Emerging evidences are 'bit by bit' revealing the mechanisms by which Staphylococci strategically disrupt normal reproductive functions. Staphylococcal species can directly or through hematogenous routes can invade the reproductive tissues. In the testicular cells, epididymis as well as in various compartments of female reproductive tracts, the pathogen recognition receptors, toll-like receptors (TLRs), can recognize the pathogen-associated molecular patterns on the Staphylococci and thereby activate inflammatory signalling pathways. These elicit pro-inflammatory mediators trigger other immune cells to infiltrate and release further inflammatory agents and reactive oxygen species (ROS). Adaptive immune responses may intensify the inflammation-induced reproductive tissue damage, particularly via activation of T-helper (Th) cells, Th1 and Th17 by the innate components or by staphylococcal exotoxins. Staphylococcal surface factors binding with sperm membrane proteins can directly impair sperm functions. Although Staphylococci, being one of the most virulent bacterial species, are major contributors in infection-induced infertility in both males and females, the mechanisms of their operations remain under-discussed. The present review aims to provide a comprehensive perception of the possible mechanisms of staphylococcal infection-induced male and female infertility and aid potential interventions to address the lack of competent therapeutic measures for staphylococcal infection-induced infertility.

Putative Microbial Population Shifts Attributable to Nasal Administration of Streptococcus salivarius 24SMBc and Streptococcus oralis 89a

Changes in bacterial composition of nasal microbiota may alter the host's susceptibility to several infectious and allergic diseases such as chronic rhinosinusitis and allergic rhinitis. The aim of this study was to evaluate the effects of 1-week administration of a probiotic product, composed by a combination of Streptococcus salivarius 24SMBc and Streptococcus oralis 89a, on the nostril microbiota. Differences in the nasal microbiota composition were investigated by using a next-generation sequencing approach. A strong and significant decrease in Staphylococcus aureus abundance was detected immediately after the bacterial administration. Moreover, comparing the microbial networks of nostril microbiota before and 1 month after the end of treatment, we detected an increase in the total number of both bacterial nodes and microbial correlations, with particular regard to the beneficial ones. Furthermore, a less abundance of microbial genera commonly associated to potential harmful bacteria has been observed. These results suggest a potential ability of S. salivarius 24SMBc and S. oralis 89a to regulate and reorganize the nasal microbiota composition, possibly favoring those microorganisms that may be able to limit the overgrowth of potential pathogens.

Therapeutic effect of Lactobacillus rhamnosus SHA113 on intestinal infection by multi-drug-resistant Staphylococcus aureus and its underlying mechanisms

Staphylococcus aureus, especially multi-drug-resistant (MDR) pathogenic S. aureus, poses a severe threat to food safety and human health. Probiotics offer promising potential for the control of MDR pathogens because of their safe and biofunctional properties. This study shows that Lactobacillus rhamnosus SHA113, a strain isolated from the milk of healthy women, could efficiently inhibit MDR S. aureus both in vitro and in vivo. In vitro, L. rhamnosus efficiently inhibited and even killed drug resistant and drug sensitive S. aureus strains. In vivo experiments showed that SHA113 could efficiently decrease the number of S. aureus cells, inhibit the expression of inflammatory factors TNF-α and IL-6, and restore the level of white cells and neutrophils in the blood. SHA113 could also efficiently repair damage of the intestinal barrier and other functions impaired by S. aureus infection. This was indicated by a change of intestinal villi length and structure, and an up-regulated expression of tight junction proteins ZO-1 and occludin. SHA113 also restored the structural damage of immune organs, such as the enlargement of the spleen and the increased level of inflammatory cytokines caused by S. aureus infection. More importantly, L. rhamnosus SHA113 showed more effective inhibitory and therapeutic effects on MDR S. aureus strain ZBQ006 than on drug sensitive S. aureus strain 29213. These results illustrated that L. rhamnosus SHA113 has great potential for the treatment of MDR S. aureus contamination as food control and for therapeutic treatment.

Intestinal epithelial barrier and neuromuscular compartment in health and disease

A number of digestive and extra-digestive disorders, including inflammatory bowel diseases, irritable bowel syndrome, intestinal infections, metabolic syndrome and neuropsychiatric disorders, share a set of clinical features at gastrointestinal level, such as infrequent bowel movements, abdominal distension, constipation and secretory dysfunctions. Several lines of evidence indicate that morphological and molecular changes in intestinal epithelial barrier and enteric neuromuscular compartment contribute to alterations of both bowel motor and secretory functions in digestive and extra-digestive diseases. The present review has been conceived to provide a comprehensive and critical overview of the available knowledge on the morphological and molecular changes occurring in intestinal epithelial barrier and enteric neuromuscular compartment in both digestive and extra-digestive diseases. In addition, our intent was to highlight whether these morphological and molecular alterations could represent a common path (or share some common features) driving the pathophysiology of bowel motor dysfunctions and related symptoms associated with digestive and extra-digestive disorders. This assessment might help to identify novel targets of potential usefulness to develop original pharmacological approaches for the therapeutic management of such disturbances.

PilVax, a novel Lactococcus lactis-based mucosal vaccine platform, stimulates systemic and mucosal immune responses to Staphylococcus aureus

Most pathogens initiate infection via the mucosa, therefore delivery of vaccines directly to the mucosa is likely to be advantageous for stimulating protective immunity at the site of entry. PilVax is a novel mucosal vaccine platform that harnesses Lactococcus lactis bacteria engineered to stably express multiple copies of vaccine peptide antigens within pili, hair-like structures which extend from the cell wall. This strategy elicited systemic and mucosal antibody responses to a model antigen after intranasal immunization, but has not been tested for its capacity to stimulate protective mucosal immunity. A well-characterized linear B-cell epitope, D3_(22-33) , from the fibronectin-binding protein A of Staphylococcus aureus was successfully introduced into PilVax and delivered intranasally to mice. Specific antipeptide immunoglobulin (Ig) G and IgA antibodies were detected in the serum and respiratory mucosa of vaccinated mice. Responses to the major pilus backbone protein Spy0128 were also assessed; robust antibody responses to this antigen were generated both systemically and in the respiratory and intestinal mucosa. Mice were challenged intranasally with the mouse-adapted S. aureus JSNZ strain and the S. aureus load quantified 7 days after challenge. Unexpectedly, exposure to PilVax, irrespective of the presence of the peptide, resulted in a significant reduction in S. aureus load in both the intestine and nasal mucosa (both P < 0.05) when compared with unvaccinated control mice. The mechanism(s) of protection are unclear, but merit further investigation to determine whether PilVax is a suitable platform for delivery of vaccine candidate antigens to the mucosa.

Burkholderia cenocepacia-host cell contact controls the transcription activity of the trimeric autotransporter adhesin BCAM2418 gene

Cell-to-cell early contact between pathogens and their host cells is required for the establishment of many infections. Among various surface factors produced by bacteria that allow an organism to become established in a host, the class of adhesins is a primary determinant. Burkholderia cenocepacia adheres to the respiratory epithelium of cystic fibrosis patients and causes chronic inflammation and disease. Cell-to-cell contacts are promoted by various kinds of adhesins, including trimeric autotransporter adhesins (TAAs). We observed that among the 7 TAA genes found in the B. cenocepacia K56-2 genome, two of them (BCAM2418 and BCAS0236) express higher levels of mRNA following physical contact with host cells. Further analysis revealed that the B. cenocepacia K56-2 BCAM2418 gene shows an on-off switch after an initial colonization period, exhibits a strong expression dependent on the host cell type, and enhances its function on cell adhesion. Furthermore, our analysis revealed that adhesion to mucin-coated surfaces dramatically increases the expression levels of BCAM2418. Abrogation of mucin O-glycans turns BCAM2418 gene expression off and impairs bacterial adherence. Overall, our findings suggest that glycosylated extracellular components of host membrane might be a binding site for B. cenocepacia and a signal for the differential expression of the TAA gene BCAM2418.

Surface display of uropathogenic Escherichia coli FimH in Lactococcus lactis: In vitro characterization of recombinant bacteria and its protectivity in animal model

Urinary tract infections (UTIs) caused by uropathogenic Escherichia coli (UPEC) are very common, leading to high patient morbidity and substantial medical costs. The development of non-antibiotic strategies such as food-grade lactic acid bacterium can be recognized as an attractive and safe alternative way against UTI. Here, we report the construction of Lactococcus lactis (L. lactis) strain genetically modified to produce FimH virulence factor of UPEC on the cell surface. We showed the FimH inserted into the pT1NX vector is actively synthesized on L. lactis. The L. lactis-pT1NX-FimH exhibited an auto-aggregation phenotype in liquid cultures and formed robust biofilm on abiotic surface compared to vector-only bacteria. Then, we developed protective biofilms with L. lactis strains and examined their inhibitory effect for exclusion of uropathogenic biofilm formation. In the natural protective biofilm assays, L. lactis-pT1NX-FimH resulted in significant reduction in the pathogen load when compared to the L. lactis-pT1NX. Evaluation of the colonization ability in the bladder showed that L. lactis expressing FimH survived better in the mice bladder than L. lactis harboring vector. Protection assay against UPEC infection was investigated using a UTI mouse model. L. lactis-pT1NX-FimH displayed high effectiveness in the protection of the bladder as compared to the control group after UPEC challenge. The results suggest that genetically engineered L. lactis-pT1NX-FimH can be used as a safe alternative way for control of biofilm formation in UPEC. Furthermore, the possibility of using L. lactis-pT1NX-FimH as a new promising strategy against UTIs caused by UPEC strains is proposed.

Growth Mode and Carbon Source Impact the Surfaceome Dynamics of Lactobacillus rhamnosus GG

Bacterial biofilms have clear implications in disease and in food applications involving probiotics. Here, we show that switching the carbohydrate source from glucose to fructose increased the biofilm formation and the total surface-antigenicity of a well-known probiotic, Lactobacillus rhamnosus GG. Surfaceomes (all cell surface-associated proteins) of GG cells grown with glucose and fructose in planktonic and biofilm cultures were identified and compared, which indicated carbohydrate source-dependent variations, especially during biofilm growth. The most distinctive differences under these conditions were detected with several surface adhesins (e.g., MBF, SpaC pilus protein and penicillin-binding proteins), enzymes (glycoside hydrolases, PrsA, PrtP, PrtR, and HtrA) and moonlighting proteins (glycolytic, transcription/translation and stress-associated proteins, r-proteins, tRNA synthetases, Clp family proteins, PepC, PepN, and PepA). The abundance of several known adhesins and candidate moonlighters, including enzymes acting on casein-derived peptides (ClpP, PepC, and PepN), increased in the biofilm cells grown on fructose, from which the surface-associated aminopeptidase activity mediated by PepC and PepN was further confirmed by an enzymatic assay. The mucus binding factor (MBF) was found most abundant in fructose grown biofilm cells whereas SpaC adhesin was identified specifically from planktonic cells growing on fructose. An additional indirect ELISA indicated both growth mode- and carbohydrate-dependent differences in abundance of SpaC, whereas the overall adherence of GG assessed with porcine mucus indicated that the carbon source and the growth mode affected mucus adhesion. The adherence of GG cells to mucus was almost completely inhibited by anti-SpaC antibodies regardless of growth mode and/or carbohydrate source, indicating the key role of the SpaCBA pilus in adherence under the tested conditions. Altogether, our results suggest that carbon source and growth mode coordinate mechanisms shaping the proteinaceous composition of GG cell surface, which potentially contributes to resistance, nutrient acquisition and cell-cell interactions under different conditions. In conclusion, the present study shows that different growth regimes and conditions can have a profound impact on the adherent and antigenic features of GG, thereby providing new information on how to gain additional benefits from this probiotic.

Probiotics to prevent Staphylococcus aureus disease?

There are a plethora of probiotic formulae that supposedly benefit human health on the market. However, the scientific underpinnings of the claimed benefits have remained poorly established. Scientific evidence is now increasingly being provided that explains those benefits, for example, by immune-stimulatory effects or inter-bacterial competition between beneficial and pathogenic bacteria. In our recent study (Piewngam et al. Nature 2018), we show that Bacillus colonization of the human intestine is negatively correlated with that of the human pathogen, Staphylococcus aureus. This type of colonization resistance is achieved by secretion of a class of lipopeptides by Bacillus species that inhibits S. aureus quorum-sensing signaling, which we found is crucial for S. aureus intestinal colonization. Here, we discuss what these findings imply for the general role of S. aureus intestinal colonization, the role of quorum-sensing in that process, and potential alternative ways to control S. aureus infection.

Invitro synergistic activity of lactic acid bacteria against multi-drug resistant staphylococci

Background

Multi-drug resistance in microorganisms is a serious problem at national as well as at a global level. Many researches have suggested alternatives to antibiotics with minimal or no major side effects. LAB is one of the most human-friendly probiotic strains known to mankind from times immemorial. With the objective to deal with progressing antibiotic resistance among microorganisms, the present work demonstrates the inhibitory activity of LAB consortium against MDR clinical isolates.

Methods

Total of nine hospital isolates of staphylococci were obtained and distinguished as S.aureus and coagulase-negative Staphylococcus (CoNS) based on their ability to ferment mannitol and form clumping with citrated plasma. All the test organisms were tested for antibiotic sensitivity with HiMedia (India) Octadisc Combi 92. Sets of L .plantarum, L .acidophilus and L.casei var. rhamnosus were prepared and tested against a standard culture of S.aureus NCIM 2129 by agar well diffusion method. To identify the primary source of substances responsible for inhibitory action, whole broth, cell-free supernatant, and cell lysate was prepared from the above-mentioned set. These were tested for their inhibitory action initially against standard S.aureus NCIM 2127, followed by clinical isolates.

Results

The antibiotic sensitivity profile revealed that all clinical isolates were multi-drug resistant. The maximum inhibitory potential was seen in a combination of the three LAB in the ratio 1:1:1. Highest antagonistic activity was observed with whole broth and cell lysate of LAB consortium. In liquid broth assay, the cell lysate of LAB consortium astoundingly exhibited up to 85% inhibition of multi-drug resistant Staphylococcus isolates.

Conclusions

Our results suggest antagonistic role of LAB metabolites against methicillin resistant staphylococci.

Pulsed electric field effects on inactivation of microorganisms in acid whey

Prospects of pulsed electric field technology application on acid whey concentrate pretreatment were analyzed. Stationary and flow pre-treatment systems were combined with different treatment parameters: electric field strength (E = 39 kV/cm, 95 kV/cm, 92 kV/cm), pulse duration (τ = 60 ns, 90 ns, 1000 ns) and pulse number (pn = up to 100 pulses). Isolates of Saccharomyces sp. and Lactobacillus sp. were predominant in concentrate. Significant non-thermal inactivation effect was achieved after PEF treatment. Exposure to short pulses selectively inactivated yeast cells, as a result PEF technology can be applied for low-energy acid whey processing.

Removal of Staphylococcus aureus from skin using a combination antibiofilm approach

Staphylococcus aureus (S. aureus) including methicillin resistant S. aureus (MRSA) is one of the primary microorganisms responsible for surgical site infection (SSI). Since S. aureus contamination is known to originate from the skin, eradicating it on the skin surface at surgical sites is an important intervention to reduce the chance of SSIs. Here we developed and evaluated the efficacy of a combination probiotic/brush sonication strategy for skin preparation at surgical, injection and insertion sites in medicine. A 24 h biofilm on porcine skin explants was used as a worst-case scenario for the evaluation of preparation strategies. Conventional ethanol wipes achieved 0.8~2 log reduction in viable bacteria depending on how many times wiped (x4 or x6). Brush sonication or probiotic supernatant pre-treatment alone achieved a similar reduction as ethanol wipes (1.4 and 0.7~1.4 log reduction, respectively). Notably, combining sonication and probiotic pre-treatment achieved a 4 log reduction in viable bacteria. In addition, probiotic supernatant incubation times as short as 2 h achieved the full effect of this reduction in the combined strategy. These findings suggest the promising potential of combination-format skin preparation strategies that can be developed to more effectively penetrate cracks and folds in the skin to remove biofilms.

Combining brush sonication with secretions from probiotic bacteria cleans skin before surgery more effectively than ethanol wipes. Researchers in the USA, led by K. Scott Phillips at the United States Food and Drug Administration, investigated removal of Staphylococcus aureus biofilm from pig skin as a “worst case” pre-surgical scenario. This bacterium is a major cause of serious and drug-resistant surgical site infections. Brush sonication or treatment with probiotic-derived solutions were individually approximately as effective as ethanol wipes, but in combination they proved substantially more effective. The treatment with the secretions surrounding probiotic bacterial cells requires exposure for several hours, but this could be readily achieved using a pre-surgery ointment. The sonication and probiotic combination could be developed into a highly effective pre-surgical procedure, penetrating cracks and folds in the skin to remove dangerous biofilms.

Melioration in Anti-staphylococcal Activity of Conventional Antibiotic(s) by Organic Acids Present in the Cell Free Supernatant of Lactobacillus paraplantarum

In view of emerging drug resistance in pathogens, there is a need to explore alternative strategies to combat infections. Use of probiotics is one such option. In this regard, efficacy of Lactobacillus plantarum has been reported against Staphylococcus aureus. Here, we propose that cell free supernatant (CFS) of Lactobacillus paraplantarum when used in combination with conventional antibiotics viz. ampicillin and oxacillin [to which the methicillin resistant Staphylococcus aureus (MRSA) strains were originally resistant] reduce the minimum inhibitory concentrations of these antibiotics, rendering the combination either synergistic or additive against the tested MRSA strain. The anti-staphylococcal activity was observed to be due to organic acids (acetic acid and lactic acid as confirmed by HPLC analysis) present in the CFS, as neutralization of the CFS with an alkali, sodium hydroxide (NaOH), caused the complete abrogation of its activity. The role of H₂O₂ and bacteriocin present in the CFS was also ruled out. The findings of this study suggest that cell free supernatant and ampicillin/oxacillin combination(s) might help in rejuvenating the use of conventional anti-staphylococcal antibiotics for the treatment of multi-drug resistant strains.

Dairy Propionibacteria: Versatile Probiotics

Dairy propionibacteria are used as cheese ripening starters, as biopreservative and as beneficial additives, in the food industry. The main species, Propionibacterium freudenreichii, is known as GRAS (Generally Recognized As Safe, USA, FDA). In addition to another dairy species, Propionibacterium acidipropionici, they are included in QPS (Qualified Presumption of Safety) list. Additional to their well-known technological application, dairy propionibacteria increasingly attract attention for their promising probiotic properties. The purpose of this review is to summarize the probiotic characteristics of dairy propionibacteria reported by the updated literature. Indeed, they meet the selection criteria for probiotic bacteria, such as the ability to endure digestive stressing conditions and to adhere to intestinal epithelial cells. This is a prerequisite to bacterial persistence within the gut. The reported beneficial effects are ranked according to property’s type: microbiota modulation, immunomodulation, and cancer modulation. The proposed molecular mechanisms are discussed. Dairy propionibacteria are described as producers of nutraceuticals and beneficial metabolites that are responsible for their versatile probiotic attributes include short chain fatty acids (SCFAs), conjugated fatty acids, surface proteins, and 1,4-dihydroxy-2-naphtoic acid (DHNA). These metabolites possess beneficial properties and their production depends on the strain and on the growth medium. The choice of the fermented food matrix may thus determine the probiotic properties of the ingested product. This review approaches dairy propionibacteria, with an interest in both technological abilities and probiotic attributes.

Mucosal Prevalence and Interactions with the Epithelium Indicate Commensalism of Sutterella spp

Sutterella species have been frequently associated with human diseases, such as autism, Down syndrome, and inflammatory bowel disease (IBD), but the impact of these bacteria on health still remains unclear. Especially the interactions of Sutterella spp. with the host are largely unknown, despite of the species being highly prevalent. In this study, we addressed the interaction of three known species of Sutterella with the intestinal epithelium and examined their adhesion properties, the effect on intestinal barrier function and the pro-inflammatory capacity in vitro. We also studied the relative abundance and prevalence of the genus Sutterella and Sutterella wadsworthensis in intestinal biopsies of healthy individuals and patients with celiac disease (CeD) or IBD. Our results show that Sutterella spp. are abundant in the duodenum of healthy adults with a decreasing gradient toward the colon. No difference was detected in the prevalence of Sutterella between the pediatric IBD or CeD patients and the healthy controls. Sutterella parvirubra adhered better than the two other Sutterella spp. to differentiated Caco-2 cells and was capable of decreasing the adherence of S. wadsworthensis, which preferably bound to mucus and human extracellular matrix proteins. Furthermore, only S. wadsworthensis induced an interleukin-8 production in enterocytes, which could be due to different lipopolysaccharide structures between the species. However, its pro-inflammatory activity was modest as compared to non-pathogenic Escherichia coli. Sutterella spp. had no effect on the enterocyte monolayer integrity in vitro. Our findings indicate that the members of genus Sutterella are widely prevalent commensals with mild pro-inflammatory capacity in the human gastrointestinal tract and do not contribute significantly to the disrupted epithelial homeostasis associated with microbiota dysbiosis and increase of Proteobacteria. The ability of Sutterella spp. to adhere to intestinal epithelial cells indicate that they may have an immunomodulatory role.

Identification of source and sink populations for the emergence and global spread of the East-Asia clone of community-associated MRSA

BACKGROUND

Our understanding of the factors influencing the emergence, dissemination and global distribution of epidemic clones of bacteria is limited. ST59 is a major epidemic clone of community-associated MRSA in East Asia, responsible for extensive morbidity and mortality, but has a much lower prevalence in other parts of the world. The geographic origin of ST59 and its international routes of dissemination are unclear and disputed in the literature.

RESULTS

To investigate the origin and spread of the ST59 clone, we obtained whole genome sequences of isolates from four continents, sampled over more than a decade, and carried out a time-scaled phylogeographic analysis. We discover that two distinct ST59 clades emerged concurrently, in East Asia and the USA, but underwent clonal expansion at different times. The East Asia clade was strongly enriched for gene determinants associated with antibiotic resistance, consistent with regional differences in antibiotic usage. Both clones spread independently to Australia and Europe, and we found evidence of the persistence of multi-drug resistance following export from East Asia. Direct transfer of strains between Taiwan and the USA was not observed in either direction, consistent with geographic niche exclusion.

CONCLUSIONS

Our results resolve a longstanding controversy regarding the origin of the ST59 clone, revealing the major global source and sink populations and routes for the spread of multi-drug resistant clones. Additionally, our findings indicate that diversification of the accessory genome of epidemic clones partly reflects region-specific patterns of antibiotic usage, which may influence bacterial fitness after transmission to different geographic locations.

Genomic and Functional Characterization of the Unusual pLOCK 0919 Plasmid Harboring the spaCBA Pili Cluster in Lactobacillus casei LOCK 0919

Here, we report the extensive bioinformatic and functional analyses of the unusual pLOCK 0919, a plasmid originating from the probiotic Lactobacillus casei LOCK 0919 strain. This plasmid is atypical because it harbors the spaCBA-srtC gene cluster encoding SpaCBA pili. We show that all other spaCBA-srtC sequences of the Lactobacillus genus that have been previously described and deposited in GenBank are present in the chromosomal DNA. Another important observation for pLOCK 0919 is that the spaCBA-srtC gene cluster and its surrounding genes are highly similar to the respective DNA region that is present in the most well-known and active SpaCBA pili producer, the probiotic Lactobacillus rhamnosus GG strain. Our results demonstrate that the spaCBA-srtC clusters of pLOCK 0919 and L. rhamnosus GG are genealogically similar, located in DNA regions that are rich in transposase genes and are poorly conserved among the publicly available sequences of Lactobacillus sp. In contrast to chromosomally localized pilus gene clusters from L. casei and Lactobacillus paracasei, the plasmidic spaC of L. casei LOCK 0919 is expressed and undergoes a slight glucose-induced repression. Moreover, results of series of in vitro tests demonstrate that L. casei LOCK 0919 has an adhesion potential, which is largely determined by the presence of the pLOCK 0919 plasmid. In particular, the plasmid occurrence positively influenced the hydrophobicity and aggregation abilities of L. casei LOCK 0919. Moreover, in vivo studies indicate that among the three Lactobacillus strains used to colonize the gastrointestinal tract of germ-free mice, already after 2 days of colonization, L. casei LOCK 0919 became the dominant strain and persisted there for at least 48 days.

Potent antagonistic activity of Egyptian Lactobacillus plantarum against multiresistant and virulent food-associated pathogens

Recent years have shown a growing interest to replace the administration of antibiotics with the application of probiotics. The aim of our investigation was to screen for promising strains with broad antimicrobial activity and also more resistant to the challenges met in the gastrointestinal tract. In our study, only 32 out of 50 (64%) probiotic isolates showed antagonistic activity against certain major extensively and pandrug-resistant Gram-positive and -negative food-borne pathogens. Fifteen L. plantarum isolates had a broad antibacterial spectrum. Among these isolates, only five presented potent antibacterial activity relative to previous studies. The recorded inhibition zone diameter ranged from 25 to 44 mm. Pronounced cell-free supernatant activities (6400–25,600 AU/ml) were commonly detected at the end of the logarithmic phase at 37°C. A marked increase in the range of activity (12,800–51,200 AU/ml) was recorded after the addition of 0.9% Na Cl to the media. Moreover, subjecting these isolates to different stressors, including high temperature, low pH, and different concentrations of bile and Na Cl, revealed different responses, and only two out of the five L. plantarum isolates showed marked resistance to all of the stress factors. Accordingly, this study highlights the intense and broad antagonistic activity induced by L. plantarum against various food associated pathogens, and their ability to resist different stressors suggests that they can be used in the food and pharmaceutical industry.

Staphylococcus aureus toxic shock syndrome toxin-1 (TSST-1) production and Lactobacillus species growth in a defined medium simulating vaginal secretions

Lactobacillus species are commensal with the healthy vaginal environment and inhibit the growth of many pathogenic bacteria in the vaginal tract by a variety of mechanisms, such as the production of hydrogen peroxide, organic acids, and antimicrobial substances. Simulation of the vaginal environment is crucial for proper investigation of the effects of Lactobacillus species on pathogenic bacteria. In this study, we modified a medium used to simulate vaginal secretions to improve the growth of toxic shock syndrome toxin-1 (TSST-1)-producing Staphylococcus aureus clinical strains and Lactobacillus species so that interactions between these bacteria may be examined. A medium consisting of basal salts, vitamins, albumin, glycogen, mucin, urea, sodium bicarbonate, polyoxyethylene sorbitan monolaurate, and amino acids supported the growth of S. aureus and the production of TSST-1 as determined by Western analysis. Improved growth of the Lactobacillus species was seen when this same medium was supplemented with manganese chloride, sodium acetate, and an increase in glucose concentration. However, growth of S. aureus in the supplemented medium resulted in reduced levels of TSST-1. Production of TSST-1 was not detected in a medium routinely used for the growth of Lactobacillus species although S. aureus growth was not inhibited. The development of an improved genital tract secretion medium provides a more authentic environment in which to study the interactions of Lactobacillus species and vaginal pathogens, such as S. aureus.

Lactobacillus rhamnosus GG inhibits the toxic effects of Staphylococcus aureus on epidermal keratinocytes

Few studies have evaluated the potential benefits of the topical application of probiotic bacteria or material derived from them. We have investigated whether a probiotic bacterium, Lactobacillus rhamnosus GG, can inhibit Staphylococcus aureus infection of human primary keratinocytes in culture. When primary human keratinocytes were exposed to S. aureus, only 25% of the keratinocytes remained viable following 24 h of incubation. However, in the presence of 10(8) CFU/ml of live L. rhamnosus GG, the viability of the infected keratinocytes increased to 57% (P = 0.01). L. rhamnosus GG lysates and spent culture fluid also provided significant protection to keratinocytes, with 65% (P = 0.006) and 57% (P = 0.01) of cells, respectively, being viable following 24 h of incubation. Keratinocyte survival was significantly enhanced regardless of whether the probiotic was applied in the viable form or as cell lysates 2 h before or simultaneously with (P = 0.005) or 12 h after (P = 0.01) S. aureus infection. However, spent culture fluid was protective only if added before or simultaneously with S. aureus. With respect to mechanism, both L. rhamnosus GG lysate and spent culture fluid apparently inhibited adherence of S. aureus to keratinocytes by competitive exclusion, but only viable bacteria or the lysate could displace S. aureus (P = 0.04 and 0.01, respectively). Furthermore, growth of S. aureus was inhibited by either live bacteria or lysate but not spent culture fluid. Together, these data suggest at least two separate activities involved in the protective effects of L. rhamnosus GG against S. aureus, growth inhibition and reduction of bacterial adhesion.

Serum bacterial toxins are related to the progression of inflammatory bowel disease

OBJECTIVES

Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is an autoimmune disease. Disorder of intestinal microbes is thought to play a critical role in the pathogenesis of IBD. Detection of bacterial toxins could become a new approach to judge the situation of this disease.

MATERIALS AND METHODS

Serum samples were collected from 142 IBD patients and 40 healthy donors as well as 15 CD patients with anti-tumor necrosis factor (TNF) monoclonal antibody (infliximab [IFX]). Enzyme-linked immunosorbent assay kits for Clostridium difficile, Escherichia coli O157, salmonella, and Staphylococcus aureus were used to analyze these bacterial toxins in sera.

RESULTS

The positive rates of bacterial toxins from C. difficile, E. coli O157, salmonella, and S. aureus in the IBD patients were found in low incidences and associated with disease duration, colonic involvement, and treatment with prednisone and immunomodulators. The active CD and UC patients had significant higher positive rates of these bacterial toxins than those in remission or healthy controls. Blockage of TNF with IFX in CD patients resulted in significant decreases of the levels of toxins of C. difficile, E. coli O157, salmonella, and S. aureus in sera.

CONCLUSIONS

Some bacterial toxins are present in the sera of active IBD patients, and patients with long disease duration, colonic involvement, or treatment with prednisone and immunomodulators are more susceptible to bacterial infection. Inhibition of inflammation with IFX would reduce the bacterial toxins via improvement of intestinal inflammation. Detecting bacteria-derived toxins in sera can be used to predict the progression of IBD.

Oral nanotherapeutics: effect of redox nanoparticle on microflora in mice with dextran sodium sulfate-induced colitis

BACKGROUND

Patients with ulcerative colitis (UC) exhibit overproduction of reactive oxygen species (ROS) and imbalance of colonic microflora. We previously developed a novel redox nanoparticle (RNP(O)), which effectively scavenged ROS in the inflamed mucosa of mice with dextran sodium sulfate (DSS)-induced colitis after oral administration. The objective of this study was to examine whether the orally administered RNP(O) changed the colonic microflora in healthy mice and those with colitis.

METHODS

RNP(O) was synthesized by self-assembly of an amphiphilic block copolymer that contains stable nitroxide radicals in hydrophobic side chain via ether linkage. Colitis was induced in mice by supplementing DSS in drinking water for 7 days, and RNP(O) was orally administered daily during DSS treatment. The alterations of fecal microflora during treatment of DSS and RNP(O) were investigated using microbiological assays.

RESULTS

We investigated that RNP(O) did not result in significant changes to the fecal microflora in healthy mice. Although total aerobic and anaerobic bacteria were not significantly different between experimental groups, a remarkable increase in commensal bacteria (Escherichia coli and Staphylococcus sp.) was observed in mice with DSS-induced colitis. Interestingly, orally administered RNP(O) remarkably reduced the rate of increase of these commensal bacteria in mice with colitis.

CONCLUSIONS

On the basis of the obtained results, it was confirmed that the oral administration of RNP(O) did not change any composition of bacteria in feces, which strongly suggests a protective effect of RNP(O) on healthy environments in intestinal microflora. RNP(O) may become an effective and safe medication for treatment of UC.

Impact of Staphylococcus aureus on pathogenesis in polymicrobial infections

Polymicrobial infections involving Staphylococcus aureus exhibit enhanced disease severity and morbidity. We reviewed the nature of polymicrobial interactions between S. aureus and other bacterial, fungal, and viral cocolonizers. Microbes that were frequently recovered from the infection site with S. aureus are Haemophilus influenzae, Enterococcus faecalis, Pseudomonas aeruginosa, Streptococcus pneumoniae, Corynebacterium sp., Lactobacillus sp., Candida albicans, and influenza virus. Detailed analyses of several in vitro and in vivo observations demonstrate that S. aureus exhibits cooperative relations with C. albicans, E. faecalis, H. influenzae, and influenza virus and competitive relations with P. aeruginosa, Streptococcus pneumoniae, Lactobacillus sp., and Corynebacterium sp. Interactions of both types influence changes in S. aureus that alter its characteristics in terms of colony formation, protein expression, pathogenicity, and antibiotic susceptibility.

Lactobacilli regulate Staphylococcus aureus 161:2-induced pro-inflammatory T-cell responses in vitro

There seems to be a correlation between early gut microbiota composition and postnatal immune development. Alteration in the microbial composition early in life has been associated with immune mediated diseases, such as autoimmunity and allergy. We have previously observed associations between the presence of lactobacilli and Staphylococcus (S.) aureus in the early-life gut microbiota, cytokine responses and allergy development in children. Consistent with the objective to understand how bacteria modulate the cytokine response of intestinal epithelial cell (IEC) lines and immune cells, we exposed IEC lines (HT29, SW480) to UV-killed bacteria and/or culture supernatants (-sn) from seven Lactobacillus strains and three S. aureus strains, while peripheral blood mononuclear cells (PBMC) and cord blood mononuclear cells (CBMC) from healthy donors were stimulated by bacteria-sn or with bacteria conditioned IEC-sn. Although the overall IEC response to bacterial exposure was characterized by limited sets of cytokine and chemokine production, S. aureus 161:2-sn induced an inflammatory response in the IEC, characterized by CXCL1/GROα and CXCL8/IL-8 production, partly in a MyD88-dependent manner. UV-killed bacteria did not induce a response in the IEC line, and a combination of both UV-killed bacteria and the bacteria-sn had no additive effect to that of the supernatant alone. In PBMC, most of the Lactobacillus-sn and S. aureus-sn strains were able to induce a wide array of cytokines, but only S. aureus-sn induced the T-cell associated cytokines IL-2, IL-17 and IFN-γ, independently of IEC-produced factors, and induced up regulation of CTLA-4 expression and IL-10 production by T-regulatory cells. Notably, S. aureus-sn-induced T-cell production of IFN- γ and IL-17 was down regulated by the simultaneous presence of any of the different Lactobacillus strains, while the IEC CXCL8/IL-8 response was unaltered. Thus these studies present a possible role for lactobacilli in induction of immune cell regulation, although the mechanisms need to be further elucidated.

Role of probiotics in the prevention and treatment of meticillin-resistant Staphylococcus aureus infections

Meticillin-resistant Staphylococcus aureus (MRSA) is a multidrug-resistant micro-organism and is the principal nosocomial pathogen worldwide. Following initial in vitro experiments demonstrating that Lactobacillus acidophilus CL1285(®) and Lactobacillus casei LBC80R(®) commercial strains exhibit antibacterial activity against clinical MRSA isolates, we conducted a literature search to find any evidence of probiotic efficacy in decolonisation or treatment of S. aureus infection. As summarised below, many strains of lactobacilli and bifidobacteria isolated from a variety of sources inhibited the growth of S. aureus and clinical isolates of MRSA in vitro. The most active strains were Lactobacillus reuteri, Lactobacillus rhamnosus GG, Propionibacterium freudenreichii, Propionibacterium acnes, Lactobacillus paracasei, L. acidophilus, L. casei, Lactobacillus plantarum, Lactobacillus bulgaricus, Lactobacillus fermentum and Lactococcus lactis. Their effects were mediated both by direct cell competitive exclusion as well as production of acids or bacteriocin-like inhibitors. L. acidophilus also inhibited S. aureus biofilm formation and lipase production. In vitro antimicrobial activity did not necessarily assure efficacy in vivo in animal infectious models, e.g. S. aureus 8325-4 was most sensitive in vitro to L. acidophilus, whilst in vivo Bifidobacterium bifidum best inhibited experimental intravaginal staphylococcosis in mice. On the other hand, L. plantarum, which showed the highest inhibition activity against S. aureus in vitro, was also very effective topically in preventing skin wound infection with S. aureus in mice. Very few clinical data were found on the interactions between probiotics and MRSA, but the few identified clinical cases pointed to the feasibility of elimination or reduction of MRSA colonisation with probiotic use.

Surface proteome analysis of a natural isolate of Lactococcus lactis reveals the presence of pili able to bind human intestinal epithelial cells

Surface proteins of Gram-positive bacteria play crucial roles in bacterial adhesion to host tissues. Regarding commensal or probiotic bacteria, adhesion to intestinal mucosa may promote their persistence in the gastro-intestinal tract and their beneficial effects to the host. In this study, seven Lactococcus lactis strains exhibiting variable surface physico-chemical properties were compared for their adhesion to Caco-2 intestinal epithelial cells. In this test, only one vegetal isolate TIL448 expressed a high-adhesion phenotype. A nonadhesive derivative was obtained by plasmid curing from TIL448, indicating that the adhesion determinants were plasmid-encoded. Surface-exposed proteins in TIL448 were analyzed by a proteomic approach consisting in shaving of the bacterial surface with trypsin and analysis of the released peptides by LC-MS/MS. As the TIL448 complete genome sequence was not available, the tryptic peptides were identified by a mass matching approach against a database including all Lactococcus protein sequences and the sequences deduced from partial DNA sequences of the TIL448 plasmids. Two surface proteins, encoded by plasmids in TIL448, were identified as candidate adhesins, the first one displaying pilin characteristics and the second one containing two mucus-binding domains. Inactivation of the pilin gene abolished adhesion to Caco-2 cells whereas inactivation of the mucus-binding protein gene had no effect on adhesion. The pilin gene is located inside a cluster of four genes encoding two other pilin-like proteins and one class-C sortase. Synthesis of pili was confirmed by immunoblotting detection of high molecular weight forms of pilins associated to the cell wall as well as by electron and atomic force microscopy observations. As a conclusion, surface proteome analysis allowed us to detect pilins at the surface of L. lactis TIL448. Moreover we showed that pili appendages are formed and involved in adhesion to Caco-2 intestinal epithelial cells.

Comparative genomic and functional analysis of 100 Lactobacillus rhamnosus strains and their comparison with strain GG

Lactobacillus rhamnosus is a lactic acid bacterium that is found in a large variety of ecological habitats, including artisanal and industrial dairy products, the oral cavity, intestinal tract or vagina. To gain insights into the genetic complexity and ecological versatility of the species L. rhamnosus, we examined the genomes and phenotypes of 100 L. rhamnosus strains isolated from diverse sources. The genomes of 100 L. rhamnosus strains were mapped onto the L. rhamnosus GG reference genome. These strains were phenotypically characterized for a wide range of metabolic, antagonistic, signalling and functional properties. Phylogenomic analysis showed multiple groupings of the species that could partly be associated with their ecological niches. We identified 17 highly variable regions that encode functions related to lifestyle, i.e. carbohydrate transport and metabolism, production of mucus-binding pili, bile salt resistance, prophages and CRISPR adaptive immunity. Integration of the phenotypic and genomic data revealed that some L. rhamnosus strains possibly resided in multiple niches, illustrating the dynamics of bacterial habitats. The present study showed two distinctive geno-phenotypes in the L. rhamnosus species. The geno-phenotype A suggests an adaptation to stable nutrient-rich niches, i.e. milk-derivative products, reflected by the alteration or loss of biological functions associated with antimicrobial activity spectrum, stress resistance, adaptability and fitness to a distinctive range of habitats. In contrast, the geno-phenotype B displays adequate traits to a variable environment, such as the intestinal tract, in terms of nutrient resources, bacterial population density and host effects.

Some bacterial species are specialists and adapted to a single niche, while others are generalists and able to grow in various environmental conditions. Lactobacillus rhamnosus is a generalist and its members can often be found in different human cavities but also in various artisanal and industrial dairy products. To gain insights into the genetic complexity and ecological versatility of this species, we collected 100 L. rhamnosus strains from different niches. Genomic and functional analysis of these revealed a dichotomy within the species that reflected its adaptation to particular niches. The variable regions identified in the L. rhamnosus genome encode lifestyle traits that allowed us to demonstrate that some L. rhamnosus isolates possibly resided in multiple habitats. Our work brings valuable data on the ecological dynamics and adaptability of the species and provides a basis for a model explaining the ecology of L. rhamnosus in an anthropocentric perspective. Finally, we observed that a set of pheno-genomic markers, i.e. CRISPR oligotyping or carbohydrate metabolism, would be sufficient and among the best ways to differentiate the L. rhamnosus strains, providing a general approach to select the highest diversity in these and other bacterial species.