Antagonistic effects ofStreptococcusandLactobacillusprobiotics in pharyngeal biofilms

Abstract

Significance and Impact of the Study: Candidate probiotic bacteria deployed to prevent or treat bacterial pharyngitis will interact with the target bacteria such as Streptococcus pyogenes as well as with the microbiota of the throat, where off-target effects are possible. Three candidate probiotics Lactobacillus acidophilus, Lactobacillus plantarum and Streptococcus salivarius reduced viability within extant S. pyogenes biofilms through the elaboration of diffusible factors other than fermentation acids but did not markedly disrupt ex situ pharyngeal microcosms. This work demonstrates the application of in vitro pharyngeal models in the preclinical testing of the safety and efficacy of candidate pharyngeal probiotics. AbstractDirect antagonism towards pathogens including Streptococcus pyogenes is a proposed mechanism of pharyngeal probiosis but off-target effects on the symbiotic microbiota of the throat are possible and may be beneficial, harmful or neutral. We have assessed the bacteriological effects of two candidate Lactobacillus probiotics and the established pharyngeal probiotic Streptococcus salivarius K12. Antagonism towards S. pyogenes and potential off-target effects were determined using sessile monospecies biofilms and pharyngeal microcosms, respectively. The candidate probiotics were antagonistic towards S. pyogenes (rank order of increasing potency, Lactobacillus acidophilus < Lactobacillus plantarum < Streptococcus salivarius) in the absence of significant acidification or cell-cell contact. Streptococcus salivarius and L. plantarum caused significant reductions in viable counts of streptococci in pharyngeal microbiotas, whilst S. salivarius also caused reductions in staphylococci. In contrast, changes in pharyngeal eubacterial DNA profiles were limited overall. In summary, the three candidate probiotics suppressed axenic Streptococcus pyogenes biofilms by mechanisms that did not depend on cell-cell contact or acidification and did not markedly destabilize complex pharyngeal microbiotas derived from healthy individuals.

Singularities of Pyogenic Streptococcal Biofilms – From Formation to Health Implication

“…Recently, Lactobacillus plantarum, Lactobacillus acidophilus, and S. salivarius were tested for inhibition toward S. pyogenes cultures in deferred antagonism agar assays. The results show that these strains have anti-biofilm effects, especially S. salivarius (Humphreys and McBain, 2019). The antagonistic effect was not dependent on cell-cell contact since the pathogen and the probiotic were not in direct contact, but separated by a semi-permeable membrane that allowed diffusion of bacteriocins as salivaricin A2 (SalA2) and salivaricin B (SboB) in the case of S. salivarius K12 (Hyink et al, 2007), acidocins (Acedo et al, 2015) and plantaricins (Lages et al, 2015), in the case of of L. acidophilus and L. plantarum, respectively (in all cases, the acidification of the media was not observed).…”

Vaginal microbiota and the potential of Lactobacillus derivatives in maintaining vaginal health

“…An increasing number of studies have elucidated the fundamental probiotic effects of Lactobacillus against pathogens present in the GI tract, oral cavity, vagina, and epidermal layer [ 149 – 152 ]. Lactobacillus acidophilus KS400 has been proven to produce bacteriocin through fermentation and inhibited the growth of urogenital pathogens such as G. vaginalis , S. agalactiae , and P. aeruginosa [ 153 ].…”

Lactobacillus commensals autochthonous to human milk have the hallmarks of potent probiotics

“…Antagonism towards S. pyogenes by some lactobacillus species is seen as a possible alternative to antibiotherapy for acute pharyngitis [74, 75], commonly reported in the local population [76]. It results in part from the production of organic acids and bacteriocins, but the ability to produce H 2 O 2 is another important mechanism of bacterial antagonism.…”