Age and disease related changes in intestinal bacterial populations assessed by cell culture, 16S rRNA abundance, and community cellular fatty acid profiles

Abstract

Background-The normal intestinal microflora plays an important role in host metabolism and provides a natural defence mechanism against invading pathogens. Although the microbiota in adults has been extensively studied, little is known of the changes that occur in the microflora with aging. These may have important consequences in elderly people, many of whom are receiving antibiotic therapy and who are most susceptible to intestinal dysbiosis. Aims-To characterise the major groups of faecal bacteria in subjects of diVerent ages using a combination of cultural, molecular, and chemotaxonomic approaches. Methods-Comparative microbiological studies were made on four diVerent subject groups: children (16 months to seven years, n=10), adults (21-34 years, n=7), healthy elderly subjects (67-88 years, n=5), and geriatric patients (68-73 years, n=4) diagnosed with Clostridium diYcile diarrhoea. Selected faecal bacteria were investigated using viable counting procedures, 16S ribosomal RNA (rRNA) abundance measurements, and the occurrence of specific signature fatty acids in whole community fatty acid methyl ester profiles. Results-The principal microbiological diVerence between adults and children was the occurrence of higher numbers of enterobacteria in the latter group, as determined by viable counts (p<0.05) and 16S rRNA (p<0.01) measurements. Moreover, a greater proportion of children's faecal rRNA was hybridised by the three probes (bifidobacteria, enterobacteria, bacteroides-porphyromonasprevotella) used in the study, indicating a less developed gut microbiota. Species diversity was also markedly lower in the Clostridium diYcile associated diarrhoea group, which was characterised by high numbers of facultative anaerobes and low levels of bifidobacteria and bacteroides. Although it was a considerably less sensitive diagnostic tool, cellular fatty acid analysis correlated with viable bacterial counts and 16S rRNA measurements in a number of bacteria, including bacteroides.Conclusions-Polyphasic analysis of faecal bacteria showed that significant structural changes occur in the microbiota with aging, and this was especially evident with respect to putatively protective bifidobacteria. Reductions in these organisms in the large bowel may be related to increased disease risk in elderly people.

Investigations into the influence of host genetics on the predominant eubacteria in the faecal microflora of children

“…This shows that the predominant eubacterial population evident in TTGE banding profiles is more complex in older children. This is likely to reflect the increasing complexity present in the microflora with age (Hopkins et al, 2001). …”

Probiotic cheese containing Lactobacillus rhamnosus HN001 and Lactobacillus acidophilus NCFM® modifies subpopulations of fecal lactobacilli and Clostridium difficile in the elderly

“…In addition, increasing evidence suggests that aging is associated with alterations in the gut microbiota (Bartosch et al 2004;Biagi et al 2010;Gavini et al 2001;Hopkins et al 2001;Hopkins and Macfarlane 2002;Mueller et al 2006;Woodmansey et al 2004). Moreover, elderly subjects living in hospitals and nursing homes are susceptible to increased pathogen challenges.…”

“…In general, the microbiota changes associated with aging are not well defined. Commonly, alterations in intestinal bifidobacteria have been associated with aging (Biagi et al 2010;Hopkins et al 2001). A recent large study investigating the gut microbiota of 161 elderly (>65 years) Irish subjects suggested that the gut microbiota of elderly is by average dominated by the phylum Bacteroidetes, more so than in the younger controls, but the variation between the elderly gut microbiota composition is substantial; for example, the proportion of the Bacteroidetes ranged from 3% to 92% within the study population (Claesson et al 2010).…”

The role of gut microbiota in the gut-brain axis: current challenges and perspectives

“…Recent evidences showed that gut microbiota plays a very important role & however, types and its frequencies of microbial organisms constituting gut microbiota in each individual are very different from each other at the species levels. The composition of the jut microbiota is established during the fi rst few years of life and is likely shaped by multiple factors, including maternal vertical transmission, genetic makeup, diet, antibiotics, infections, and stress (Hopkins and Sharp, 2001; Lewis and Cochrane, 2007;Cecilia and Sonja, 2010;Brian et al, 2013). Since the jut microbiota is a key player of the mucosal homeostasis, dysregulation of the intestinal mucosa homeostasis is consequentially implicated in the progression of disorders.…”