Antimicrobial Activities of Neem Extract ( Azadirachta indica ) Against Microbial Pathogens of Animal Origin

摘要

The antimicrobial activity of neem extract at different concentrations was evaluated using agar-welldiffusion method against 13 microbial pathogens strains of animal origin. Results revealed that the neemextract has great bactericidal activities at lower concentrations 10 and 50% than at concentrations above 75 to100%. Diluted neem extract showed bactericidal activities against Gram negative bacteria but did not againstGram positive bacteria. Zone of inhibition reached 14 and 12 mm against Citrobacter, 19 and 18 mm againstKlebsiella, 18 and 17 mm against S. bodyi, 18 and 15 mm against S. sonnei, 13 and 12mm against S. flexeneri,14 and 12 mm against E. coli O157, 17 and 15 mm against E. coli O78, 14 and 13 mm against E. coli O26 and16and 14 mm against Salmonella at conc. 10 and 50%, respectively. Neem extract has no antibacterial activitiesagainst tested Gram positive bacteria; S. aureus and MRSA. Against mycotic isolates only 10 % of Neemextract showed fungicidal effect with zone of inhibition 25 and 20 mm against C. albicans and Asp. flavus,respectively. Neem extract was evaluated for its capability for hindrance of bacterial count in ground beef aswell as monitoring of its capability for hindrance of E. coli O157 ATCC 700728 inoculated in ground meat.Neem extract significantly decreases bacterial count Mean± SD from 1.90±0.35 to 0.0064±0.0002cfu/ml beforeand after addition of neem, respectively. Inoculated of ground meat with E. coli O157 ATCC 700728 in relationto addition of 10% neem extract, showed significant decline of aerobic bacterial count Mean± SD from78.00±2.31cfu/ml to 0.0310±0.0015cfu/ml and E. coli count from 0.60±0.23 to 0.0012±0.0002, respectively.Results concluded that, diluted neem extract showed great antimicrobial properties at low concentration (10%)with significant decrease of bacterial count after addition of 10% neem extract. It is recommended that furtherwork should be done to identify the specific ingredient(s) responsible for this effect, purify it and standardizeas a preservative against microbial contaminant of food from animal origin.