Title : Antagonistic activity of bacteriocin-producing strain Streptococcus salivarius K12
Abstract:
Introduction:
One of the urgent problems of the modern healthcare is increasing resistance of pathogenic microorganisms to antibiotics and a further trend toward an increasing number of antibiotic-resistant strains. Therefore, it is necessary to introduce new ways to combat resistant microorganisms. In this regard, the use of probiotics in clinical practice becomes the most promising direction in the prevention of new cases of bacterial infections caused by resistant microbes. Probiotics are live microorganisms that when administered in adequate amounts confer a health benefit on the host by changing the properties of the normal microbiota. One is the most promising probiotic strain is Streptococcus salivarius. Streptococcus salivarius is a gram-positive streptococcus, which is one of the first colonizers of human oral and nasopharynx mucosa. Among S. salivarius there are two main well-studied strains: S. salivarius K12 (SsK12) and S. salivarius M18 (SsM18) which are currently used as oral probiotics.
Aim:
To evaluate the antagonistic activity of Streptococcus salivarius K12 (SsK12) against ENT and oral cavity infections pathogens (S. pneumoniae, S. pyogenes, S. aureus), gram-negative bacteria (E. coli, P. aeruginosa) and C. albicans.
Materials and methods:
The probiotic strain SsK12 was isolated from dietary supplement, containing at least 1 × 109 CFU per tablet. The tablet was dissolved in the enrichment broth. The resulting suspension was seeded on 5% blood agar and incubated at 35°C in 4-6% CO2 for 48 hours. The raised culture was identified as Streptococcus salivarius with MALDI-TOF mass spectrometry method. The evaluation of SsK12 antagonistic activity was carried out using a perpendicular streak technique. The daily SsK12 culture was inoculated as heavy streaks with
a loop at one side of Petri dish with the Muller-Hinton agar (MHA) and incubated for 24 hours at 350 C in anaerobic conditions. It was supposed that bacteriocins would diffuse over the whole area of the agar media. On the next day S. pneumoniae, S. pyogenes, S. aureus, E. coli,
P. aeruginosa and C. albicans clinical isolates were streaked at the clear side of MHA Petri dish.
MHA Petri dish inoculated with SsK12 (one part) and with the respective clinical isolates (another part) streaked perpendicularly on the same day was used as the control.
Results:
There was no growth of S. pyogenes on the Petri dish with SsK12 daily culture; the growth of a few colonies of S. pneumonia was noted. The growth of S. aureus, E. coli,
P. aeruginosa and C. albicans was noted along the inoculated streak. On the control Petri dish with simultaneous inoculating of the SsK12 strain and the test cultures, the growth of all the testes isolates was noted.
Conclusions:
- SsK12 possesses perfect antagonistic activity against S. pyogenes and good activity against S. pneumoniae.
- There was no antagonistic activity of SsK12 against S. aureus, E. coli, P. aeruginosa and C. albicans.
- SsK12 antagonistic properties make it possible to use this probiotic strain for prophylaxis of recurrent ENT infections.
Keywords: bacteriocins; antagonistic activity; Streptococcus salivarius K12; SsK12; ENT infections.
