The colonic microbiota mediates many cellular and molecular events in the host that are important to health. These processes can be affected in the elderly, because in some individuals, the composition and metabolic activities of the microbiota change with age. Detailed characterizations of the major groups of fecal bacteria in healthy young adults, in healthy elderly people, and in hospitalized elderly patients receiving antibiotics were made in this study, together with measurements of their metabolic activities, by analysis of fecal organic acid and ammonia concentrations. The results showed that total anaerobe numbers remained relatively constant in old people; however, individual bacterial genera changed markedly with age. Reductions in numbers of bacteroides and bifidobacteria in both elderly groups were accompanied by reduced species diversity. Bifidobacterial populations in particular showed marked variations in the dominant species, with Bifidobacterium angulatum and Bifidobacterium adolescentis being frequently isolated from the elderly and Bifidobacterium longum, Bifidobacterium catenulatum, Bifidobacterium boum, and Bifidobacterium infantis being detected only from the healthy young volunteers. Reductions in amylolytic activities of bacterial isolates in healthy elderly subjects and reduced short-chain fatty acid concentrations supported these findings, since bifidobacteria and bacteroides are important saccharolytic groups in the colon. Conversely, higher numbers of proteolytic bacteria were observed with feces samples from the antibiotic-treated elderly group, which were also associated with increased proteolytic species diversity (fusobacteria, clostridia, and propionibacteria). Other differences in the intestinal ecosystem in elderly subjects were observed, with alterations in the dominant clostridial species in combination with greater numbers of facultative anaerobes.Bacterial succession in the infant large bowel has been well documented both by culture (6, 52) and, more recently, by using molecular methods (10,16,54), but there have been relatively few studies dealing with changes in the colonic microbiota during the aging process. We therefore know little about the composition of bacterial populations or their metabolic activities in elderly people. Advances in medical science and improved living standards have led to an increased life expectancy in western societies, where people over 60 currently constitute one-fifth of the population, and this number is estimated to rise to one-third by the year 2030 (36).Good nutrition is important in maintaining gastrointestinal function. Malnutrition is one of the main factors responsible for reduced immune responses in old people (28), and the development of preventative nutritional strategies to promote healthy aging is desirable. Increased thresholds for taste and smell (8, 55), resulting in preferences for bland foods, coupled with swallowing difficulties (5) and masticatory dysfunction caused by loss of teeth and muscle bulk (25, 43) can result in ...

Summary Advancements in science and medicine, as well as improved living standards, have led to a steady increase in life expectancy, and subsequently a rise in the elderly population. The intestinal microbiota is important for maintenance of host health, providing energy, nutrients and protection against invading organisms. Although the colonic microbiota is relatively stable throughout adult life, age‐related changes in the gastrointestinal (GI) tract, as well as changes in diet and host immune system reactivity, inevitably affect population composition. Recent studies indicate shifts in the composition of the intestinal microbiota, which may lead to detrimental effects for the elderly host. Increased numbers of facultative anaerobes, in conjunction with a decrease in beneficial organisms such as the anaerobic lactobacilli and bifidobacteria, amongst other anaerobes, have been reported. These changes, along with a general reduction in species diversity in most bacterial groups, and changes to diet and digestive physiology such as intestinal transit time, may result in increased putrefaction in the colon and a greater susceptibility to disease. Therapeutic strategies to counteract these changes have been suggested in ageing people. These include dietary supplements containing prebiotics, probiotics and a combination of both of these, synbiotics. Limited feeding trials show promising results with these supplements, although further longer‐term investigations are required to substantiate their use in elderly healthcare fields.

The human large intestine is covered with a protective mucus coating, which is heavily colonized by complex bacterial populations that are distinct from those in the gut lumen. Little is known of the composition and metabolic activities of these biofilms, although they are likely to play an important role in mucus breakdown. The aims of this study were to determine how intestinal bacteria colonize mucus and to study physiologic and enzymatic factors involved in the destruction of this glycoprotein. Colonization of mucin gels by fecal bacteria was studied in vitro, using a two-stage continuous culture system, simulating conditions of nutrient availability and limitation characteristic of the proximal (vessel 1) and distal (vessel 2) colon. The establishment of bacterial communities in mucin gels was investigated by selective culture methods, scanning electron microscopy, and confocal laser scanning microscopy, in association with fluorescently labeled 16S rRNA oligonucleotide probes. Gel samples were also taken for analysis of mucin-degrading enzymes and measurements of residual mucin sugars. Mucin gels were rapidly colonized by heterogeneous bacterial populations, especially members of the Bacteroides fragilis group, enterobacteria, and clostridia. Intestinal bacterial populations growing on mucin surfaces were shown to be phylogenetically and metabolically distinct from their planktonic counterparts.Epithelial surfaces in the human gastrointestinal tract are covered by a layer of mucus, which prevents most microorganisms reaching and persisting on the mucosal surface (13). This viscoelastic gel (1) is protective against adhesion and invasion by many pathogenic microorganisms, bacterial toxins, end products of metabolism, pancreatic endopeptidases, microbial antigens, and other damaging agents present in the lumen of the bowel. The mucus gel mainly consists of water (ca. 95%) and glycoproteins (1 to 10%), which are responsible for its viscosity and gel-forming properties (18), as well as electrolytes, proteins, antibodies, and nucleic acids (1).Mucins are chemically and structurally diverse molecules, but they invariably contain large quantities of galactose and hexosamines with lesser amounts of fucose. Strongly polar groups such as neuraminic (sialic) acids and sulfate are also present, although to a highly variable degree (49). The carbohydrate moieties occur as linear and branched oligosaccharides, which can constitute up to 85% of the molecule by weight (53). These oligosaccharides are attached to a protein core via serine or threonine residues. The attachment of sulfate and sialic acids to terminal mucin oligosaccharides confers resistance to digestion by glycosidases (8).

Synbiotic consumption increased the size and diversity of protective fecal bifidobacterial populations, which are often very much reduced in older people.

Biofilms are prevalent in non‐healing chronic wounds and implicated in delayed healing. Tolerance to antimicrobial treatments and the host's immune system leave clinicians with limited interventions against biofilm populations. It is therefore essential that effective treatments be rigorously tested and demonstrate an impact on biofilm across multiple experimental models to guide clinical investigations and protocols. Cadexomer iodine has previously been shown to be effective against biofilm in various in vitro models, against methicillin‐resistant Staphylococcus aureus biofilm in mouse wounds, and clinically in diabetic foot ulcers complicated by biofilm. Similarities between porcine and human skin make the pig a favoured model for cutaneous wound studies. Two antiseptic dressings and a gauze control were assessed against mature biofilm grown on ex vivo pig skin and in a pig wound model. Significant reductions in biofilm were observed following treatment with cadexomer iodine across both biofilm models. In contrast, silver carboxymethylcellulose dressings had minimal impact on biofilm in the models, with similar results to the control in the ex vivo model. Microscopy and histopathology indicate that the depth of organisms in wound tissue may impact treatment effectiveness. Further work on the promising biofilm efficacy of cadexomer iodine is needed to determine optimal treatment durations against biofilm.