Exploring the In Vitro Antibacterial Potential of Specific Probiotic Strains against Oral Pathogens

Abstract

The microbiota in the oral cavity has a strict connection to its host. Its imbalance may determine oral diseases and can also have an impact on the systemic health. Probiotic strains may help in the restoration of a balanced condition. For this purpose, we screened the antibacterial and antiadhesive activities of many viable probiotic strains (Lactobacillus acidophilus PBS066, Lactobacillus crispatus LCR030, Lactobacillus gasseri LG050, Lactiplantibacillus plantarum PBS067, Limosilactobacillus reuteri PBS072, Lacticaseibacillus rhamnosus LRH020, Bifidobacterium animalis subsp. lactis BL050, Lacticaseibacillus paracasei LPC 1101, L. paracasei LPC 1082, and L. paracasei LPC 1114) against two main oral pathogens, Streptococcus mutans and Aggregatibacter actinomycetemcomitans, involved in dental caries and periodontal disease development and progression. Considering both the agar overlay preventive and treatment models, seven probiotics determined greater inhibition zones against the tested pathogens. This behavior was further analyzed by the plate count method and scanning electron microscope imaging. L. plantarum PBS067, L. rhamnosus LRH020, L. paracasei LPC 1101, L. paracasei LPC 1082, and L. paracasei LPC 1114 prevent the growth and adhesion of oral pathogens in a strain-specific manner (p < 0.0001). These probiotics might be considered as an alternative effective adjuvant to improve oral and systemic well-being for future personalized treatments.

Keywords: dysbiosis; host interaction; infection; microbiota; oral; pathogens; probiotics.

Figure 1

Representative image of inhibition halos. L. crispatus LCR030 antibacterial activity against A. actinomycetemcomitans in the preventive (bottom part of the plate) and treatment (top of the plate) models. The halo areas were indicated by dashed blue lines and the diameters were measured; the results were expressed in mm.

Figure 2

Pathogen colony forming unit (CFU) counts. Probiotic efficacy against (a) S. mutans and (b) A. actinomycetemcomitans adhesion and colonization. Results are expressed as mean ± SD of 3 independent experiments. * p < 0.05; **** p < 0.0001 vs. control (pristine medium only).

Figure 3

Representative images of probiotic efficacy in reducing pathogen adhesion. Probiotic inhibition of S. mutans and A. actinomycetemcomitans growth and adhesion at magnification 5000× ((a–h); (i–p)) and 10,000× ((a’–h’); (i’–p’)), respectively. The images were acquired by using a scanning electron microscope (SEM). The red arrows indicate the pathogen cells that were present. Yellow squares indicate the magnificated areas for S. mutans, blue squares for A. actinomycetemcomitans. LCR030: L. crispatus LCR030; LG050: L. gasseri LG050; LP PBS067: L. plantarum PBS067; LRH020: L. rhamnosus LRH020; LPC 1101: L. paracasei LPC 1101; LPC 1082: L. paracasei LPC 1082; LPC 1114: L. paracasei LPC 1114. Scale bars of 5 µm and 1 µm were shown in 5000× and 10,000× images, respectively.