The effect of three frequently applied antibiotics on the colonization resistance of the digestive tract of mice

Abstract

SUMMARYThe influence of treatment with increasing oral doses of three absorbable antibiotics on the colonization resistance of the digestive tract was investigated in mice. Mice treated with ampicillin or epicillin in any of the applied doses had a strongly decreased colonization resistance as demonstrated by ‘bacterial over-growth’ after contamination with resistant strains ofEscherichia coli. After a treatment period of 2 weeks,Streptococcus faecalisbecame resistant in a number of animals. Oral treatment with cephradine on the other hand had no obvious influence on the endogenous flora of the mice, nor was the colonization resistance decreased.

Effect of twelve antimicrobial drugs on the colonization resistance of the digestive tract of mice and on endogenous potentially pathogenic bacteria

“…Endogenous S. faecalis was suppressed during treatment with high doses of penicillin V, cloxacillin and rifamycin. Both oral cephalosporins, cephalexin and cefaclor acted in the same way as cephradine in a previous study (Thijm & Van der Waaij, 1979). They did not influence CR and were not suppressive to endogenous (sensitive) enterobacteria.…”

The Intestinal Microbiota Influences Campylobacter jejuni Colonization and Extraintestinal Dissemination in Mice

“…Colonization resistance, or the ability of the commensal microbiota to prevent colonization by exogenous pathogens or opportunistic commensals, is an important part of the host defense (34). Intestinal microbiota provide colonization resistance to pathogens in multiple ways, including competition for niches by preventing pathogens from attaching to their target sites, depleting essential nutrients for pathogen viability, producing bacteriocins or other metabolites that inhibit pathogen function, producing organic acids that alter intraluminal pH levels to acidic conditions unfavorable to pathogens, or utilizing the limited oxygen available in the gut contributing to the anaerobic and capnophilic environment (35)(36)(37)(38).…”

Colonization resistance

“…Moreover, in mice which have been treated with streptomycin (6,34), penicillin (17), or ampicillin (45) and in germ-free mice (18,24), the concentration of aerobic gram-negative challenge strains in feces is between 1,000-and 100,000-fold higher than the normal level of GNB in the feces of mice (about 105 CFU/g of feces).…”