Exploring Oral Microbiota for Probiotic Development: Identification and Antibiotic Resistance Profile of Promising Strains

Abstract

This study aimed to isolate and characterize cultivable probiotic bacterial strains from the oral cavity of healthy young adults for potential development of autoprobiotic formulations. Oral samples from buccal mucosa, dorsal tongue surface, and gingival pockets of 10 healthy individuals (aged 20-23 years) were collected and cultured on cabbage agar. From 16 initial isolates, 12 strains were successfully identified using MALDI-TOF mass spectrometry as Lacticaseibacillus rhamnosus (2 strains), Limosilactobacillus fermentum (7 strains), Lactobacillus jensenii (1 strain), and Streptococcus salivarius (2 strains). Buccal mucosa demonstrated the highest microbial diversity (9/12 strains). Antibiotic susceptibility testing using the disk diffusion method against azithromycin, vancomycin, and clindamycin (commonly used in dentistry) revealed universal vancomycin resistance across L. rhamnosus and most L. fermentum strains, with S. salivarius strains 8 and 15 also resistant. Notably, L. fermentum strains 4.2 and 2, and S. salivarius strain 15 exhibited intermediate sensitivity to azithromycin (10.3 mm, 13.6 mm, 12.6 mm) and clindamycin (14.6 mm, 9.6 mm, 10.6 mm), respectively, identifying these as optimal candidates for oral probiotic, symbiotic, and autoprobiotic development due to their balanced resistance/susceptibility profile and site-specific colonization patterns.