Antibiofilm activity of silver nanoparticles against biofilm forming Staphylococcus pseudintermedius isolated from dogs with otitis externa.

BACKGROUND: Silver nanoparticles (AgNPs) are known to possess antimicrobial properties. Although the antibiofilm activity of AgNPs has been demonstrated in humans, this activity has not yet been elucidated in veterinary medicine. OBJECTIVES: The purpose of this study was to evaluate the antibiofilm activity of silver nanoparticles against Staphylococcus pseudintermedius. METHODS: Ten isolates of S. pseudintermedius obtained from dogs with otitis externa were treated with AgNPs, and the antibiofilm activity was measured using a modified microtiter plate and Congo red agar (CRA) method and scanning electron microscopy. RESULTS: AgNPs displayed a significant dose-dependent antibiofilm activity and reduced biofilm formation at concentrations of 20 and 10 µg/ml (p < 0.05). S. pseudintermedius exposed to 20 µg/ml of AgNPs formed less bacterial slime compared to the controls on CRA plates. Scanning electron micrographs showed that the biofilm had few individually scattered cells along its surface when treated with AgNP concentrations of 20 and 10 µg/ml. Untreated surfaces showed an aggregated biofilm. CONCLUSIONS: Our results suggested that AgNP may be a valuable alternative antibiofilm agent for canine otitis externa.

Effects of cooking methods on the ß-carotene levels of selected plant food materials.

In the present study, the ß-carotene contents of 14 plant food materials prepared by boiling, steaming, or baking or when they are raw were analyzed and compared. After boiling three pulse species, namely, peas, kidney beans, and dried mung beans, ß-carotene contents of peas and kidney beans increased significantly, whereas that of mung beans (dried material) decreased. True retention factors of ß-carotene contents in the cooked kidney beans, peas, and mung beans after boiling were 174.2, 128.3, and 91.8%, respectively. After steaming, the ß-carotene content of regular millets significantly decreased but that of taros increased, in which the true retention factors were observed with ß-carotene contents of 72.4% in the steamed regular millets and 160.9% in the steamed taros. Moreover, ß-carotene contents in yellow-fleshed sweet potato (raw: 896.2 µg/100 g) decreased by baking (786.4 µg/100 g) and steaming (steaming: 553.1 µg/100 g). These results suggest that ß-carotene contents in the selected plant food materials markedly depend on the cooking method and plant food materials classification.