Lia-Mara Ditu

Modulation of virulence and antibiotic susceptibility of enteropathogenic Escherichia coli strains by Enterococcus faecium probiotic strain culture fractions

The increasing rate of antimicrobial resistance drastically reduced the efficiency of conventional antibiotics and led to the reconsideration of the interspecies interactions in influencing bacterial virulence and response to therapy. The aim of the study was the investigation of the influence of the soluble and cellular fractions of Enterococcus (E.) faecium CMGB16 probiotic culture on the virulence and antibiotic resistance markers expression in clinical enteropathogenic Escherichia (E.) coli strains. The 7 clinical enteropathogenic E. coli strains, one standard E. coli ATCC 25,922 and one Bacillus (B.) cereus strains were cultivated in nutrient broth, aerobically at 37 °C, for 24 h. The E. faecium CMGB16 probiotic strain was cultivated in anaerobic conditions, at 37 °C in MRS (Man Rogosa Sharpe) broth, and co-cultivated with two pathogenic strains (B. cereus and E. coli O28) culture fractions (supernatant, washed sediment and heat-inactivated culture) for 6 h, at 37 °C. After co-cultivation, the soluble and cellular fractions of the probiotic strain cultivated in the presence of two pathogenic strains were separated by centrifugation (6000 rpm, 10 min), heat-inactivated (15 min, 100 °C) and co-cultivated with the clinical enteropathogenic E. coli strains in McConkey broth, for 24 h, at 37 °C, in order to investigate the influence of the probiotic fractions on the adherence capacity and antibiotic susceptibility. All tested probiotic combinations influenced the adherence pattern of E. coli tested strains. The enteropathogenic E. coli strains susceptibility to aminoglycosides, beta-lactams and quinolones was increased by all probiotic combinations and decreased for amoxicillin-clavulanic acid. This study demonstrates that the plurifactorial anti-infective action of probiotics is also due to the modulation of virulence factors and antibiotic susceptibility expression in E. coli pathogenic strains.

Immunomodulatory effect of non-viable components of probiotic culture stimulated with heat-inactivated Escherichia coli and Bacillus cereus on holoxenic mice

Background Competition of probiotic bacteria with other species from the intestinal microbiota involves different mechanisms that occur regardless of probiotics’ viability. The objective of this paper was to assess the cytokine serum levels in holoxenic mice after oral administration of non-viable components (NVC) of Enterococcus faecium probiotic culture stimulated with heat-inactivated Escherichia coli and Bacillus cereus in comparison to NVC of unstimulated E. faecium probiotic culture. Methods Probiotic E. faecium CMGb 16 culture, grown in the presence of heat-inactivated cultures of E. coli and B. cereus CMGB 102, was subsequently separated into supernatant (SN) and heat-inactivated cellular sediment (CS) fractions by centrifugation. Each NVC was orally administered to holoxenic mice (balb C mouse strain), in three doses, given at 24 hours. Blood samples were collected from the retinal artery, at 7, 14, and 21 days after the first administration of the NVC. The serum concentrations of IL-12 and tumor necrosis factor-alpha (TNF-α) interleukins were assessed by ELISA method. Results After the oral administration of SN component obtained from the probiotic culture stimulated with heat-inactivated cultures of B. cereus CMGB 102 and E. coli O28, the serum concentrations of IL-12 were maintained higher in the samples collected at 7 and 14 days post-administration. No specific TNF-α profile could be established, depending on stimulated or non-stimulated probiotic culture, NVC fraction, or harvesting time. Conclusion The obtained results demonstrate that non-viable fractions of probiotic bacteria, stimulated by other bacterial species, could induce immunostimulatory effects mediated by cytokines and act, therefore, as immunological adjuvants.

Soft tissue engineering and microbial infections: Challenges and perspectives

Irrespective of the tissue engineering application, the three main actors involved are the biomaterial, which represents the scaffold for the new tissue, the stem or progenitor cells, and the bioactive substances stimulating the in vitro and in vivo proliferation and the differentiation of the respective cells. The increased use of biomaterials in the medical field resulted in an increased rate of biomaterial-associated microbial infections, which are persistent and very difficult to treat. Recent progress in the field of biomaterials suggests that biomaterials could exhibit excellent and long-lasting intrinsic antimicrobial properties, which in many cases do not interfere with their biocompatibility features. Moreover, biomaterials dedicated for soft tissue engineering could be functionalized or doped with antimicrobial substances, either inorganic (metallic nanoparticles) or organic (natural and synthetic compounds) using adequate scaffold-processing methods. However, a clear elucidation of the interaction between the antimicrobial substances and the other host components implicated in tissue formation would certainly contribute to the identification of the optimal solutions. Tissue engineering applications could therefore benefit from the design of multifunctional biomaterials, assuring simultaneously the scaffold function, as well as the release of antibiotics, growth factors, and other bioactive molecules, in order to prevent infections and therefore to accelerate optimal tissue regeneration.Abstract Irrespective of the tissue engineering application, the three main actors involved are the biomaterial, which represents the scaffold for the new tissue, the stem or progenitor cells, and the bioactive substances stimulating the in vitro and in vivo proliferation and the differentiation of the respective cells. The increased use of biomaterials in the medical field resulted in an increased rate of biomaterial-associated microbial infections, which are persistent and very difficult to treat. Recent progress in the field of biomaterials suggests that biomaterials could exhibit excellent and long-lasting intrinsic antimicrobial properties, which in many cases do not interfere with their biocompatibility features. Moreover, biomaterials dedicated for soft tissue engineering could be functionalized or doped with antimicrobial substances, either inorganic (metallic nanoparticles) or organic (natural and synthetic compounds) using adequate scaffold-processing methods. However, a clear elucidation of the interaction between the antimicrobial substances and the other host components implicated in tissue formation would certainly contribute to the identification of the optimal solutions. Tissue engineering applications could therefore benefit from the design of multifunctional biomaterials, assuring simultaneously the scaffold function, as well as the release of antibiotics, growth factors, and other bioactive molecules, in order to prevent infections and therefore to accelerate optimal tissue regeneration.

Introduction in Nutraceutical and Medicinal Foods

Abstract Eating habits have a great impact on humans’ health, environment, industry, and economy. In recent years, new topics in food research, such as nutraceuticals, functional foods, and food supplements, have emerged to mitigate health problems, especially those pertaining to metabolism and the gastrointestinal tract. Although the intimate mechanisms by which nutraceuticals, functional foods, and food supplements may improve the health of consumers are widely unknown, the potential of such products in supporting health and the development of efficient alternative therapies for numerous severe diseases is of great significance and supported by numerous studies and empirical observations. The purpose of this manuscript is to introduce, define, and briefly discuss types of nutraceuticals, functional foods, food supplements, and medicinal foods, highlighting their potential impact on consumers’ health.

Aspects of Gut Microbiota and Immune System Interactions in Infectious Diseases, Immunopathology, and Cancer

The microbiota consists of a dynamic multispecies community of bacteria, fungi, archaea, and protozoans, bringing to the host organism a dowry of cells and genes more numerous than its own. Among the different non-sterile cavities, the human gut harbors the most complex microbiota, with a strong impact on host homeostasis and immunostasis, being thus essential for maintaining the health condition. In this review, we outline the roles of gut microbiota in immunity, starting with the background information supporting the further presentation of the implications of gut microbiota dysbiosis in host susceptibility to infections, hypersensitivity reactions, autoimmunity, chronic inflammation, and cancer. The role of diet and antibiotics in the occurrence of dysbiosis and its pathological consequences, as well as the potential of probiotics to restore eubiosis is also discussed.

Introduction in Soft Chemistry and Food Fermentation

Abstract Biotechnology (term composed of bios and technique ) is based on the industrial exploitation of productive potentiality of microorganisms, plant or animal cells, or their subcellular fractions, to obtain useful products. The progress of general microbiology, biochemistry, molecular biology, and biotechnologies led to a new science, industrial microbiology, and thereby, to industrial exploitation of new potentiality of microorganisms: antibiotic synthesis; enzyme production; production of alcoholic beverages; biofuel production; food preservation; and bioremediation of air, soil, and water contamination. Fermentation, a term derived from the Latin verb fevere (to boil), is one of the oldest methods of processing food and is the most important process in the food industry, playing many roles in the enrichment of the human dietary, food preservation, and biological enrichment of food substrates. Fermentation is a natural process achieved by microorganisms, subsequently used by humans on an industrial scale, but not invented by man. Industrial microbiology use different microorganisms, such as naturally occurring organisms, laboratory selected mutants, or even genetically modified organisms, to produce a very large variety of industrial products for human interest. This chapter provides an overview of general data regarding the fermentation process, industrial microorganisms, and their metabolites, fermented food, and health benefits.

Antibiotic Drug Delivery Systems for the Intracellular Targeting of Bacterial Pathogens

Intracellular bacterial pathogens are hard to treat because of the inability of conventional antimicrobial agents belonging to widely used classes, like aminoglycosides and β-lac‐ tams, fluoroquinolones, or macrolides to penetrate, accumulate, or be retained in the mammalian cells. The increasing problem of antibiotic resistance complicates more the treatment of the diseases caused by these agents. In many cases, the increase in therapeu‐ tic doses and treatment duration is accompanied by the occurrence of severe side effects. Taking into account the huge financial investment associated with bringing a new antibi‐ otic to the market and the limited lifetime of antibiotics, the design of drug delivery sys‐ tems to enable the targeting of antibiotics inside the cells, to improve their activity in different intracellular niches at different pH and oxygen concentrations, and to achieve a reduced dosage and frequency of administration could represent a prudent choice. An ideal drug delivery system should possess several properties, such as antimicrobial activ‐ ity, biodegradability, and biocompatibility, making it suitable for use in biomedical and pharmaceutical formulations. This approach will allow reviving old antibiotics rendered useless by resistance or toxicity, rescuing the last line therapy antibiotics by increasing the therapeutic index, widening the antimicrobial spectrum of antibiotics scaffolds that failed due to membrane permeability problems, and thus reducing the gap between in‐ creasingly drug-resistant pathogens and the development of new antibiotics. Different improved drug carriers have been developed for treating intracellular pathogens, includ‐ ing antibiotics loaded into liposomes, microspheres, polymeric carriers, and nanoplexes. The purpose of this chapter is to present the limitations of each class of antibiotics in tar‐ geting intracellular pathogens and the main research directions for the development of drug delivery systems for the intracellular release of antibiotics.

Bioactive nanomaterials for cartilage and muscle regeneration

Despite the recent biomedical advances in diagnosis and therapy, cartilage and muscle disorders represent debilitating conditions with massive economical, social and clinical impacts. Severe complications of such difficult-to-treat or untreatable diseases limit current therapeutic approaches and lead to the acute need for development of novel therapeutic or reparatory strategies. Current research is increasingly focused on finding or obtaining suitable materials with specific biomedical traits to be used as competitive candidates in the engineering of new tissues and organs to replace or heal damaged tissues. The purpose of this study is to present the most prevalent cartilage- and muscular-tissue-related diseases and highlight the recent scientific progress regarding the development of classical and recent therapeutic approaches, focusing on discussing the impact and advantages of bioactive nanomaterials in designing functional scaffolds for cartilage and muscle repair.