Streptococcus pyogenes is the persistent cause of purulent infections in humans. Biofilm formation is one of the important aspects of its pathogenicity. S. pyogenes biofilm communities favor significant resistance to antibiotic therapy. Analyzing novel sources against biofilm forming pathogens is therefore an important alternative treatment measure. In the present study we attempted to determine the antibiofilm activity of medicinal plants Piper longum and Piper nigrum against streptococcal biofilms. The chloroform, ethyl acetate, methanol and petroleum ether extracts of P. longum and P. nigrum grains were assessed for their anti-biofilm property in clinical isolates of S. pyogenes and a reference strain S. pyogenes MTCC 1924. The antibacterial activity test revealed that chloroform and petroleum extracts inhibited the test bacteria than other extract. The solvent extracts of both the plants showed an MIC at 2-4 mg/ml, depending on the solvent used.Growth curve analysis revealed that all the plant extracts did not have any effect on the bacterial growth at sub MIC level. The antibiofilm assay of various plant extracts showed varying degree of inhibition Ethyl acetate > Methanol > Chloroform > Petroleum Ether in a dose (0.5-2 mg/ml) dependant manner without affecting the bacterial growth. The methanol and ethyl acetate extracts of P. longum and P. nigrum showed significant (p < 0.05) biofilm inhibition in the range of 85 % to 96 % whereas the BIC of chloroform and petroleum ether extracts were significant 71 % to 84 % at a concentration of 2 mg/ml respectively. Streptolysin S activity of the isolates treated with plant extracts showed significant (p < 0.05) decrease as compared to control. Light microscopic and CLSM images proved the inhibition of S. pyogenes biofilm at varying concentrations.

Disease management has become prominent in aquaculture due to emergence of antibiotic resistant pathogens and overuse of chemotherapeutic agents. One among the developmental strategies to control disease outbreak is by enhancing the fish immunity using immunostimulants. The use of dietary herbal immunostimulants can improve the immune defence of fishes, providing resistance against infections. The present study evaluated the possible effects of Limonia acidissima L. fruit (wood apple) supplemented diets on the growth, innate immunity and disease resistance against Aeromonas hydrophila in Catla fish. Catla catla fingerlings (mean weight 5.0 ± 0.5 g) were separated into four groups and cultivated in 100-L tank. Each group was fed with diets supplemented with 0 g, 1.5 g, 3 g and 6 g per 100 g feed twice daily. Fish were examined for growth and innate immune parameters at 30 days interval up to 120 days. Results revealed that wood apple supplemented diets enhanced the growth and innate immune responses of Catla during the feeding trial. Growth performance, haematological parameters, biochemical parameters and immunological indices significantly (p < 0.05) increased in fish fed with experimental diets. The relative survival percentage after A. hydrophila challenge increased in fish fed with Limonia acidissima diet. Thus, the result suggested that fish fed Limonia acidissima Fruit supplemented diet enhanced growth, improved immune system and increased survival rate in C. catla fingerlings.