The digestive tract in immunocompromised patients: importance of maintaining its resistance to colonization, especially in hospital in-patients and those taking antibiotics

Abstract

The colonization resistance (CR) of the gastrointestinal tract to potential pathogens depends partly on factors within the host but to a greater extent on the normal (anaerobic) gut flora. Its strength varies between individuals. These individual differences in resistance to colonization by pathogenic microorganisms may explain differences in susceptibility to infection. CR is lowered by remission-inducing treatment (radiation and/or chemotherapy) in leukaemia, but more severely by certain antibiotics. Development (by selection or transfer) of resistance to these antibiotics may lead to overgrowth and penetration of the mucosal lining by the overgrowing (potentially) pathogenic bacteria. Other antibiotics however, if sufficiently dosed, have been found to eliminate (potential) pathogens selectively without decreasing CR. This selective decontamination of the gastrointestinal tract has been successfully used prophylactically in neutropenic patients but needs to be monitored bacteriologically. It should perhaps be used more widely in the hospital to control development and spread of antibiotic-resistant strains.

Chemotherapy Treatment in Pediatric Patients with Acute Myeloid Leukemia Receiving Antimicrobial Prophylaxis Leads to a Relative Increase of Colonization with Potentially Pathogenic Bacteria in the Gut

“…Several factors can be responsible for the decrease in both diversity and number of intestinal microbiota in patients with cancer: (1) nasal tube feeding, (2) (prophylactic) antibiotic treatment, and (3) chemotherapy itself [10,30,39].…”

“…An adequate characterization of intestinal microbiota is necessary to investigate the supposed relationship among colonization resistance, mucositis, intestinal inflammation, and infection. Previous studies have investigated the effect of chemotherapeutics and/or antibiotics on intestinal microbiota [10][11][12]. However, most of these studies were hampered by the restrictions of culturing techniques, because a large fraction of intestinal bacteria has never been cultured and thus escape detection.…”

The colonization resistance of the digestive tract in different animal species and in man; a comparative study

“…Inter-individual differences within one animal species therefore, reflect the relation between the quality of an individual's CR and the contamination level. The assumption that a greater exposure to Enterobacteriaceae may result in a higher mean and range of biotypes per faecal sample in a particular animal species is plausible, since this was observed in a previously published controlled experiment in mice [10]. During the experimental period, 36 conventional mice were maintained inside a germ-free isolator with, in total, 12 different biotypes of Enterobacteriaceae.…”

A vegan or vegetarian diet substantially alters the human colonic faecal microbiota

“…This function is partly fulfilled by anaerobic species like Bacteroides and Bifidobacterium, but Lactobacillus, Escherichia coli and Enterococcus species also contribute to the barrier microbiota. This feature called 'colonisation resistance ' (Van der Waaij, 1984) is not based on one single mechanism, but is rather described as a variety of different mechanisms complementing one another: first of all, the dominant microbiota inhibits colonisation of pathogens by occupying mucosa receptors and dense population of the superimposed mucin layer (Savage, 1977). A second strategy is based on releasing bacteriostatically or microbicidally acting substances (such as short-chain fatty acids, hydrosulphide, hydrogen peroxide, antibiotics), which additionally inhibit the growth of pathogenic germs (Hentges, 1983).…”