Investigation of antibiotic resistance of lactobacilli isolated from probiotics

Objective: This study aims to evaluate the current and potential risks associated with antibiotic resistance in lactobacilli, an important group of probiotic microorganisms. In particular, it investigates the presence of antibiotic resistance genes in strains used as probiotics, the transferability of these genes, and their potential to be transmitted to other bacteria. Methods: Lactobacillus species isolated from 11 different probiotic products were examined for their antibiotic susceptibility. The isolates were identified using MALDI-TOF MS, and their antibiotic resistance profiles were evaluated using disk diffusion and E-test methods. Additionally, resistance genes were investigated via PCR, and their antibiotic inactivation capacities were tested. Results: All Lactobacillus strains were found to be resistant to streptomycin, while they were 100% susceptible to ampicillin, cefazolin, tetracycline, rifampin, and chloramphenicol. The resistance genes aac(6')-Ie-aph(2'')-Ia, rmtB, linA, and linB were detected. However, no gene transfer was observed through conjugation or transformation. A plasmid was detected in one sample, sequenced, and found not to contain any resistance genes. Conclusion: Our study indicates that antibiotic resistance is prevalent among Lactobacillus strains. However, due to the limited number of studies on this topic, further research is needed to better understand the risks and mechanisms involved. Keywords: Lactobacillus, antibiotic, resistance, transfer