Page 71 - Read Online

Page 8 of 13 Martin et al. Microbiome Res Rep 2023;2:17 https://dx.doi.org/10.20517/mrr.2023.10

Excessive antibiotic use appears to be a risk factor for certain chronic diseases [127,128] . Antibiotics are known
to cause significant perturbations in the gut microbiota [112,129] and promote dysbiotic states. The extent to
which an antibiotic alters the microbiota depends on the spectrum of the antibiotic, dose, and duration of
[112]
administration . Antibiotic use for extended periods opens a window of opportunity to acquire ARB
through the loss of colonization resistance [Figure 1] . Resistant bacteria are generally present in the gut
[74]
[112]
microbiota but at very low levels [74,115] , and antimicrobial therapy increases ARB selection . Moreover,
hospitalization results in significant exposure to ARB . Similarly, germ-free or antibiotic-treated animals
[112]
develop severe infections compared to conventional animals, such as Salmonella enterica serovar
Typhimurium or Listeria monocytogenes, owing to the lack of colonization resistance provided by the
[72]
microbiome .

Probiotics belonging to Lactobacillus and Bifidobacterium have a long history of use in foods and
supplements, contributing to the balance of the gut microbiota [130,131] . There are several applications where
these probiotics are recommended, such as infant colic, allergies, and antibiotic administration .
[132]
Colonization resistance limits the growth of probiotic bacteria, which usually only transit through the GI
tract; permanent colonization is uncommon for probiotics . Moreover, transient colonization is highly
[133]
individualized during the consumption of probiotics . Usually, probiotic applications do not consider
[134]
colonization resistance or probiotic interactions with other members of the microbiota, which outnumber
probiotics by at least 1,000 times . Some studies have suggested that colonization is not necessary for its
[74]
effects on the host .
[132]
CONCLUSIONS
Microbial interactions represent the inner connections of the gut microbiota and contribute to its protective
role through colonization resistance against pathogens, ARB, or probiotics. Antibiotics and a low-fiber diet
play a role against colonization resistance, resulting in dysbiosis with a concomitant reduction in BPB and
an increased chance of colonization by foreign microbes. Bifidobacterium species are key members of the
gut microbiota and participate in multiple cross-feeding interactions with species of the same genus and
other distant species, for example, by sharing SCFAs or monosaccharides. While there are few examples
showing how some bifidobacteria display beneficial effects to the host and a balanced gut ecosystem, the
mechanisms, microbial interactions, or metabolites involved in their protective role are largely unknown
and remain the subject of future studies.

DECLARATIONS
Authors’ contributions
Made substantial contributions to the conception and design of the study and performed data analysis and
interpretation: Serebrinsky-Duek K, Riquelme E, Saa PA, Martin AJM, Garrido D
Performed data acquisition and provided administrative, technical, and material support: Riquelme E, Saa
PA, Martin AJM, Garrido D

Availability of data and materials
Not applicable.

Financial support and sponsorship
ANID Fondecyt Regular 1230764, 1190074 and 1191526, ANID Fondequip EQM190070; Centro Ciencia &
Vida, FB210008, Financiamiento Basal para Centros Científicos y Tecnológicos de Excelencia de ANID.