Microbiological Testing of Probiotic Preparations.

Probiotic microorganisms that are potentially beneficial to the health of the host are commercially available in a great variety of products. Not all microorganism strains present in products have proven beneficial to the health properties. These products include not only foodstuffs but also dietary supplements, food for special medical purposes, medicinal products, as well as cosmetics and medical devices. These products contain from one to a dozen bacterial strains of the same or different species and sometimes also fungal strains. Since the pro-health effects of probiotics depend on a specific strain, the number of its cells in a dose, and the lack of pathogenic microorganisms, it is extremely important to control the quality of probiotics. Depending on the classification of a given product, its form, and its content of microorganisms, the correct determination of the number of microorganisms and their identification is crucial. This article describes the culture-dependent and culture-independent methods for testing the contents of probiotic microorganisms, in addition to biochemical and genetic methods of identification. The microbiological purity requirements for various product categories are also presented. Due to numerous reports on the low quality of probiotic products available on the market, it is important to standardise research methods for this group of products and to increase the frequency of inspections of these products.

Assessment of the Microbiological Status of Probiotic Products.

The aim of this study was to perform the microbiological analysis of quality of 25 probiotic products, available on the Polish market. Analysis of bacterial viability in probiotic products showed that not all of these preparations possess a suitable number of bacteria. Moreover, some of the tested probiotic products contained bacterial strains other than those declared by the manufacturer. All tested strains recovered from probiotic products were found to be resistant to metronidazole and susceptible to nitrofurantoin. The susceptibility to other antibiotics was strain specific. Probiotic products should be subject to regular and thorough inspection by appropriate institutions.

[Evaluation of biocidal properties of silver nanoparticles against cariogenic bacteria]. / Ocena bakteriobójczej aktywnosci koloidalnego roztworu nanoczastek srebra w stosunku do bakterii próchnicotwórczych.

INTRODUCTION: Antimicrobial properties of silver nanoparticles (SNP's) have been recentl well evaluated, and now are being considered as excellent candidates for therapeutic purposes. It is confirmed, that various solutions of colloidal SNP's possess significant antibacterial properties against such species as: Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa even at low concentrations, although there have been so far only a few researches evaluating antimicrobial activity of SNP's against cariogenic bacteria: Streptococcus mutans, Streptococcus salivarius and Streptococcus mitis responsible for initiation of dental carries. Tooth decay is infectious disease an worldwide, which may occur in patients of every age. Nanotechnology creates a new approach of designing of medical devices preventing or reducing bacterial colonization. METHODS: Colloidal silver solution (CSS) of concentration 350 ppm was used in this research. Nanoparticles size, shape and solution stability were evaluated. 16 strains of cariogenic bacteria, 4 isolates of each species: S. mutans, S. salivarius, S. sanguinis and S, mitis were obtained from plaque swabs of 7 patients treated for dental carries at Department of Conservative Dentistry, Medical University of Warsaw. MIC and MBC values for CSS's were evaluated. RESULTS: CSS used in this research is of good stability. No agglomeration or coalescence was observed during 24 hours of experiment. Silver nanoparticles were of round shape and had mean size of 67 nm. MIC values were: 12-25 ppm for S. salivarius, 25 ppm for S. sanguinis, 50-100 ppm for S. mitis and 50 ppm for S. mutans, while MBC values after 1 hour of bacterial contact with nanoparticles were 200-350 ppm for all cariogenic bacterial species. After 24 hours of contact MBC values were: 25-50 ppm for S. salivarius and S. sanguinis, 100-200 ppm for S. mitis and 200 ppmfor S. mutans. CONCLUSIONS: Antimicrobial properties of CSS depend on nanoparticles concentration and interaction time with bacteria. The susceptibility of cariogenic oral streptococci to silver nanoparticles is diversified. Sufficient concentration which inhibited all cariogenic bacteria in our research was 200 ppm after long (24 hours) period of silver nanoparticles interaction with bacteria.