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Analysis of Antibiotic Susceptibility of Lactobacillus Strains Isolated from Adolescent Gut Microbiota

N E Smurova1, A S Gorkavenko2, R E Zugeeva2

  • 1Scientific Centre for Family Health and Human Reproduction Problems, Irkutsk, Russia. nadinasmurova@mail.ru.

Bulletin of Experimental Biology and Medicine
|June 2, 2026
PubMed

Insights

This study assessed antibiotic susceptibility in 46 Lactobacillus strains from adolescent gut microbiota. Most strains showed susceptibility to common antibiotics, with no transmissible resistance genes detected, suggesting potential probiotic safety.

Area of Science:

  • Microbiology
  • Probiotics
  • Gut Microbiota

Background:

  • Lactobacillus species are key components of the gut microbiota.
  • Candidate probiotic strains require thorough safety assessments, including antibiotic susceptibility.
  • Understanding antibiotic resistance patterns in Lactobacillus is crucial for probiotic development.

Purpose of the Study:

  • To determine the phenotypic antibiotic susceptibility of 46 Lactobacillus strains isolated from healthy adolescent gut microbiota.
  • To evaluate the presence of specific transmissible antibiotic resistance genes (tetW, cat-TC, ermC) in these strains.
  • To identify Lactobacillus strains with favorable antibiotic susceptibility profiles for potential probiotic applications.

Main Methods:

  • Phenotypic antibiotic susceptibility testing was performed on 46 Lactobacillus strains.
  • Detection of plasmid DNA was conducted.
  • Screening for transmissible antibiotic resistance genes (tetW, cat-TC, ermC) in both genomic and plasmid DNA was performed.

Main Results:

  • All 46 Lactobacillus strains were susceptible to amoxicillin.
  • Most strains showed susceptibility to tetracycline, clindamycin, erythromycin, chloramphenicol, and ampicillin, with some requiring extended exposure.
  • Twenty-seven strains exhibited phenotypic resistance to oxacillin; plasmid DNA was found in eight strains. No transmissible resistance genes were detected.

Conclusions:

  • The study identified Lactobacillus strains with varying antibiotic susceptibility profiles.
  • The absence of detectable transmissible resistance genes (tetW, cat-TC, ermC) is a positive indicator for probiotic safety.
  • Further genetic analysis is recommended to fully confirm the safety profile of these candidate probiotic strains.

Keywords:
antibiotic susceptibilitylactobacilliplasmid DNAprobiotictransmissible antibiotic resistance genes

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