Bifidobacterium bifidum G9-1 Survives in the Intestinal Environment and Influences the Gut Microbiota Despite the Presence of Antimicrobials.

2025-06-29
Microbiology and immunology 69(9)

PubMed: 40582892
DOI: 10.1111/1348-0421.13230

Study Design

Population: germ-free and specific pathogen-free mice
Methods: Minimum inhibitory concentrations were determined in vitro by culturing B. bifidum G9-1 with antimicrobials and assessing its viability. For in vivo analysis, germ-free and specific pathogen-free mice were administered B. bifidum G9-1 along with antimicrobials. Gut microbiota composition and viable B. bifidum G9-1 abundance were determined.

Animal Study

Probiotics can help prevent antibiotic-associated diarrhea; however, those lacking antimicrobial resistance may be ineffective during antimicrobial treatment. Here, we aimed to examine the effects of antimicrobials on the probiotic strain Bifidobacterium bifidum G9-1 (BBG9-1). Minimum inhibitory concentrations were determined in vitro by culturing B. bifidum G9-1 with antimicrobials and assessing its viability. For in vivo analysis, germ-free and specific pathogen-free mice were administered B. bifidum G9-1 along with antimicrobials. Gut microbiota composition and viable B. bifidum G9-1 abundance were determined. Bifidobacterium bifidum G9-1 was highly sensitive to antimicrobials in vitro. However, in a complex bacterial environment mimicking the gut environment, the abundance of viable B. bifidum G9-1 was significantly high despite antimicrobial exposure. Dominant bacterial populations were more affected by antimicrobials than nondominant populations, with B. bifidum G9-1 exhibiting increased viability in the presence of diverse bacterial species. In vivo, combined administration of antimicrobials and B. bifidum G9-1 significantly reduced B. bifidum G9-1 abundance in germ-free mice but not in specific pathogen-free mice, where the gut microbiota composition shifted following administration of B. bifidum G9-1. The presence of diverse live bacteria in the intestine promotes the survival of B. bifidum G9-1 and its beneficial effects, even in the presence of antimicrobials. This finding suggests that B. bifidum G9-1, despite lacking intrinsic antimicrobial resistance, can survive and reach the large intestine, maintaining its probiotic function. Therefore, B. bifidum G9-1 can potentially be used for antibiotic-associated diarrhea prevention.

Research Insights

Supplement	Dose	Health Outcome	Effect Type	Effect Size	Source
Bifidobacterium bifidum G9-1	—	Enhanced Gut Colonization	Beneficial	Moderate	View source the abundance of viable B. bifidum G9-1 was significantly high despite antimicrobial exposure... the presence of diverse live bacteria in the intestine promotes the survival of B. bifidum G9-1 and its beneficial effects, even in the presence of antimicrobials.
Bifidobacterium bifidum G9-1	—	Reduced Incidence of Antibiotic-Associated Diarrhea	Beneficial	Moderate	View source Probiotics can help prevent antibiotic-associated diarrhea... Bifidobacterium bifidum G9-1 can potentially be used for antibiotic-associated diarrhea prevention.