The capacity to inhibit a pathogen, either from a bacteria or a substance with antibiotic properties, is usually determined in vitro in a growth medium with agar in Petri dish, where the pathogen is growing and where the substance or bacteria to evaluate is placed.
This classical method is based on the presence of an inhibition zone around a hole of 8 mm in which the bacteria or antibiotic substance is placed. The diameter of the inhibition zone around the hole classifies the inhibitory capacity in four grades:
- Grade 0: no inhibition zone.
- Grade 1: inhibition zone from 8 to 11 mm.
- Grade 2: inhibition zone from 11 to 14 mm.
- Grade 3: inhibition zone more than 14 mm.
The degree of inhibition is proportional to the diameter, then, the product with Grades 2 and 3 in the test are considered optimal to counteract the growth of the pathogen studied.
The following graphs show the results of inhibition of different assays with Megaflora 9 evo, or with the specific strains it contains, on various pathogens.
Megaflora 9 evo has demonstrate to have a high degree inhibiting pathogens belonging to the family Enterobacteriaceae such as E. coli, Shigella, Salmonella and Proteus agglomerans. In all cases, the degree of inhibition was 3 with a value of the inhibition zone over 14 mm.
Growth inhibition of Enterobacteriaceae
In another test, the individual inhibitory capacity of some strains of Megaflora 9 evo on the growth of Candida albicans was evaluated. The results showed different degree of inhibition depending on the strain, being L. plantarum and L. salivarius the most active. L. salivarius, in particular, showed a 100% inhibition of Candida growth. Also, Lactococcus lactis showed good inhibition with a score of more than 80%.
Growth inhibition of Candida albicans
In a third test, it was determined the inhibitory capacity of Clostridium difficile growth at 24 and 48 hours of incubation, as well as the production of toxins A and B. In this case, Enterococcus faecium W54 strain presented the most potent inhibitory capacity, with a significant inhibition of growth at 24h and total at 48h. Other strains, as L. paracasei W20 and L. salivarius W24, present in Megaflora 9 evo also inhibited the total Clostridium growth at 48 h.
Concerning the inhibition of the production of toxins A & B besides of the strains mentioned also Bifidobacrtrium lactis W51 was also able to inhibit totally the production of these enterotoxins.
It is interesting to compare the results of this study with the inhibition of Candida albicans, because it justifies the presence of multispecies and multi-strain in the mixture. While Enterococcus faecium W54 showed no inhibition on candidas but was the most active inhibiting the growth of Clostridium difficile.
Growth inhibition of Clostridium difficile