Lactic acid bacteria from healthy oral cavity of Thai volunteers: inhibition of oral pathogens.

The aims of the present study were to screen and characterize the antimicrobial lactic acid bacteria which were isolated from healthy oral cavities of Thai volunteers, and to characterize their inhibiting substances. Among 3790 isolates (suspected to be lactic acid bacteria) from 130 volunteers, five showed an appreciable effect against Sarcina lutea ATCC 9341, Bacillus cereus ATCC 11778, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 6538, Streptococcus mutans DTMU 1, Strep. salivarius DTMU 1, Strep. sanguis DTMU 1, Candida albicans ATCC 13803 and C. albicans DTMU 2, as well as the oral pathogens. These antimicrobial isolates included L17 and N14 which showed the antibacterial activity, D14 which showed the anticandidal activity, and D6 and N8 which showed both the antibacterial and anticandidal activities. The isolates were later found to be facultative anaerobic, Gram-positive, non-spore-forming, non-capsule-forming and catalase-negative bacilli. They could utilize casein but could not hydrolyse starch, and they produced hydrogen peroxide and bacteriocins. Their antimicrobial potentials were found to be affected by pH, catalase, proteolytic enzymes and temperature. The activity was partially inactivated after catalase treatment, significantly declined at pH > or =9.0 or after trypsin and pepsin treatments, and also reduced after heating at > or =100 degrees C. However, the antimicrobial activity of these five isolates was somewhat resistant to heat. When the isolates were tested for their antimicrobial sensitivity, they were shown to be sensitive to a number of antimicrobial agents. The final identification revealed that D6, D14 and N14 were Lactobacillus paracasei subsp. paracasei, and L17 and N8 were Lact. rhamnosus.

Intraoral candida in Thai diabetes patients.

The purpose of this study was to determine the oral candidal prevalence and identify the candidal species in fifty four diabetes and sixty two healthy, non smoking and non denture wearing subjects. The modified imprint culture technique was used for candidal isolation. It was found that the prevalence of oral candida was significantly higher in diabetics (P < 0.00001) with the relative risk of positive culture at 3.674 (95% CI = 1.998-6.757). The most frequent candidal species in diabetics were C. albicans (81.3%) followed by C. glabrata (9.4%), C. tropicalis (3.1%) and C. rugosa (3.1%). There were two species of C. tropicalis and C. rugosa in one subject (3.1%). The candidal species in healthy subjects was only C. albicans (100%).

[Glass bead sterilization of orthodontic pliers].

The study on sterilization of orthodontic pliers by using glass bead sterilizer at 450 F was performed. Microorganisms used in this experiment were Staphylococcus aureus ATCC 25933, Bacillus subtilis ATCC 6633, Candida albicans ATCC 10231 and mixed microorganisms in human saliva. The result showed that after the pliers were scrubbed with alcohol and sterilized for 3 minutes with glass bead sterilizer, all vegetative cells and bacterial spores were killed in every test. This study indicated that glass bead sterilizer is capable of sterilizing orthodontic pliers and can be a useful adjunct when rapid chairside sterilization is desired.

Haemophili in developing dental plaque.

Evidence for a possible role played by oral haemophili in the development of dental plaque was sought by studying the occurrence of these bacteria in early dental plaque of smooth surfaces and occlusal fissures in six dental students. The mean number of haemophili per 10(3) anaerobes in early smooth surface plaque (18 h) and fissure plaque (7 d) was 95 and 22 respectively. Examination of 988 Haemophilus isolates revealed that H. parainfluenzae was the only species in samples of fissure plaque, whereas some samples from smooth surfaces, in addition to the predominating and ubiquitous H. parainfluenzae, yielded growth of the two species H. segnis and H. aphrophilus. It is concluded that haemophili are among the primary colonizers of smooth surfaces of teeth.