The larvae of the wax moth Galleria mellonella and human oral keratinocytes were used to investigate the protective activity of the candidate oral probiotics Lactobacillus rhamnosus GG (LHR), Lactobacillus reuteri (LR), and Streptococcus salivarius K-12 (SS) against the periodontal pathogens Fusobacterium nucleatum (FN), Porphyromonas gingivalis (PG), and Aggregatibacter actinomycetemcomitans (AA). Probiotics were delivered to the larvae (i) concomitantly with the pathogen in the same larval pro-leg; (ii) concomitantly with the pathogen in different pro-legs, and (iii) before inoculation with the pathogen in different pro-legs. Probiotics were delivered as viable cells, cell lysates or cell supernatants to the oral keratinocytes concomitantly with the pathogen. The periodontal pathogens killed at least 50% of larvae within 24 h although PG and FN were significantly more virulent than AA in the order FN > PG > AA and were also significantly lethal to mammalian cells. The candidate probiotics, however, were not lethal to the larvae or human oral keratinocytes at doses up to 10 7 cells/larvae. Wax worm survival rates increased up to 60% for some probiotic/pathogen combinations compared with control larvae inoculated with pathogens only. SS was the most effective probiotic against FN challenge and LHR the least, in simultaneous administration and pre-treatment, SS and LR were generally the most protective against all pathogens (up to 60% survival). For P. gingivalis, LR > LHR > SS, and for A. actinomycetemcomitans SS > LHR and LR. Administering the candidate probiotics to human oral keratinocytes significantly decreased the toxic effects of the periodontal pathogens. In summary, the periodontal pathogens were variably lethal to G. mellonella and human oral keratinocytes and the candidate probiotics had measurable protective effects, which were greatest when administrated simultaneously with the periodontal pathogens, suggesting protective effects based on bacterial interaction, and providing a basis for mechanistic studies.

Plasma, a mix of ionized gas molecules and free electrons, is often referred to as the fourth state of matter. There are different applications of plasma in our life starts from easy lighting to disease fighting and it's nothing new. Fluorescent lights, air conditions and plasma televisions use it. One of its different types is atmospheric cold plasma, the possible applications for sterilization using cold plasmas range from the food industry to planetary space missions. The same technique could also be used on space craft leaving Earth to avoid transporting microorganisms from Earth to other planets or moons. The use of toxic chemicals to sterilize medical instruments may soon be a thing of the past because the use of cold plasma to sterilize heat-sensitive reusable medical tools in a rapid, safe, and effective way is bound to replace the present method which uses a toxic gas as ethylene oxide, in addition to its use for air purification. Lately it is tested to prepare surfaces for bonding and kill bacteria on delicate living tissues. We report the results of an interdisciplinary collaboration formed to assess the sterilizing capabilities of the cold atmospheric plasma. This newly-invented source of plasma is capable of operating at atmospheric pressure in air and other gases, and of providing antimicrobial activity at room temperature as judged by viable plate counts. Plasma exposures have reduced log numbers of three tested bacterial strains namely, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa seeded on solid surfaces of Muller-Hinton agar at room temperature. Initial experimental data showed ≥5 log 10 CFU reduction of bacteria when 5×10 6 cfu.ml-1 of samples seeded on MHA plates. Results showed >5 log 10 CFU reduction with E. coli when exposed for up to 360 sec to plasma while the same exposure time was required for 5 log 10 CFU reduction killing with S. aureus samples, the least affected by this treatment was Pseudomonas aeruginosa cell suspensions where there was a very few reduction in number of survivals (≤ 10% of the whole population) after the same exposure time application. For all microorganisms tested, a biphasic curve was generated when the number of survivors versus time was plotted in dose-response curves. In conclusion we can report that the atmospheric cold plasma generated by this method has proven sterilization (kill) capability against both gram-positive and gramnegative bacteria in different extents depending on special strain characteristics.

No abstract

Background Frequent use of mouthwash (MW) is one of the most effective methods used to prevent oral bacterial infections and to assist individuals in their efforts to achieve and maintain better oral health. Using a MW containing antibacterial agents would be a simple way to prevent growth and multiplication of pathogenic organisms in oral cavity causing dental caries and other mouth diseases. Chlorhexidine (CHX) and Hexetidine (HX) have been proposed as potent biocides against oral bacteria. Objective The present study was performed to investigate oral bacteria growth inhibition when using any of four mouthwashes that are commercially available in the Libyan market and contain either CHX, (Zordy land Oraxin), or HX, (Hextril and Givalex), and to clarify whether CHX and HX were suitable and safe biocides that can be included in mouthwash products. Materials and Methods Sixty adult (45 females and 15 males) volunteers had been chosen and divided into four groups and their saliva samples were assessed for microbial count at the beginning and the end of two weeks of treatment, during which they rinsed with 15ml of mouthwashes for 30 seconds twice a day (morning and evening) in addition to their usual oral hygiene procedures. The antibacterial activity of mouthwashes was assayed by cell viable count technique and cell diffusibility measurement. Results The results showed wide variations in the effectiveness of mouthwashes; those containing CHX were more effective (P ≤0.05) than formulations containing HX on oral microbial count. The main findings of the present study were that Zordyl, Oraxinand Hextril exerted high effects on the salivary microbiota, causing 90%, 60% and 34% reduction in salivary bacterial counts respectively. 25% reduction was observed for Givalex. On the other hand, the zone of inhibition test showed that Zordyl and Oraxin had large zone inhibitory effects, while Hextril and Givalex, were less effective on some bacterial species. Conclusion It can be concluded that twice daily use of CHX mouthwash (CHX-MW) or HX mouthwash (HX-MW) reduces oral bacterial load counts in healthy subjects when used as an adjunct to their normal oral hygiene procedures. This also suggests that inhibitory power of mouth washes containing CHX is greater on oral bacteria than mouthwashes containing HX.