Probiotics for the Prevention and Treatment of Clostridium difficile in Older Patients

Jasmin Islam; Jonathan Cohen; Chakravarthi Rajkumar; Martin J. Llewelyn


Age Ageing. 2012;41(6):706-711. 

In This Article

The Ageing Host

The fact that CDI almost exclusively affects older people is only partly explained by healthcare contact and burden of predisposing diseases. It is now clear that ageing itself predisposes to CDI. The gut microflora develops during infancy and remains stable through adult life. Colonisation resistance is the process by which the normal microflora competes for nutrients and receptor-binding sites and prevents pathogen overgrowth.[9] However, in old age the faecal microflora becomes less diverse with an overall reduction in anaerobic bacteria and bifidobacteria.[10] A range of changes in intestinal physiology accompany ageing and may predispose to CDI. These include increased mucosal permeability and declines in secretory IgA, defensins and gastric acid.[11] Failure of adequate pathogen clearance can result in chronic low-grade activation of the immune system often referred to as 'inflammaging', which has been linked to an increased incidence of diabetes and increased frailty.[12]

The immune system exhibits age-related changes in both innate and adaptive immune responses known as 'immunosenescence' which have been reviewed elsewhere.[13] In brief, older people have a reduced number and functionality of phagocytic cells. The humoral response is compromised by reductions in the number of B lymphocytes, in antibody diversity and antibody affinity. T cell receptor diversity is also reduced.