Macrolide Resistance in Lactobacillus Isolates: A Growing Concern

Strategic Insights -

Commensal bacteria such as Lactobacillus isolates can transfer determinants of resistance to pathogens, making the study of antibiotic resistance in these bacteria crucial. Researchers in Milan, Italy, examined the development of resistance in 40 isolates of Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus crispatus, and Lactobacillus casei. They found that 14 isolates were resistant to macrolides and 4 isolates were resistant to tetracycline.

Key Takeaways:

  • Resistance to macrolides and/or tetracycline was identified in 18 isolates, with 14 resistant to macrolides and 4 resistant to tetracycline.
  • The ermB gene and A2058G mutation in 23S rRNA were detected in macrolide-resistant isolates.
  • Frequencies of mutation of susceptible isolates (n=26) were lower for ampicillin and erythromycin than for tetracycline.
  • Serial exposure to antibiotics led to selection of resistant mutants, but acquired resistance was rather unstable and was lost after subcultures in antibiotic-free medium in most mutants.
  • Resistance to erythromycin was associated with a A2058G mutation in 23S rRNA.
  • Lactobacilli, often used as probiotics, may acquire resistance to antibiotics, highlighting the need to evaluate their ability to acquire resistance for use in probiotic products.

Statistics:

  • 40 isolates of Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus crispatus, and Lactobacillus casei were examined.
  • 14 isolates were resistant to macrolides.
  • 4 isolates were resistant to tetracycline.
  • 26 isolates were susceptible and used for mutation frequency analysis.
  • Serial exposure to antibiotics led to the selection of resistant mutants in most cases.

Sources:

  • Journal of Microbiology, 2011;49(4):651-6 (Macrolide resistance and in vitro selection of resistance to antibiotics in Lactobacillus isolates).
  • Biotech Week, 2011, via NewsRx.com.