author(s)
Lena Saad Abdullah and Prof. Dr. Mohammad Jwaid Alwan

abstract
In order to determine the efficiency of silver nanoparticles in mastitis treatment induced by E. coli O157:H7, 30 animals were infected intramammary with 1X10² cfu/ml of virulence E. coli O157:H7 isolated from milk of bovine mastitis and at 48hr post inoculation, the animals were divided randomly into four groups equally, 1^st group treated with AgNPs orally and Ciprofloxacin via intramammary 2^nd group treated as 1^st group but AgNPs were intramammary 3rd group left without treatment, 4th group was inoculated intramammary with 0.05ml of sterile normal saline and served as control negative, five animals from each group were sacrificed at 7 and 14 days post infection. Results showed severe pathological lesions with heavy bacterial isolation in oral treatment animals (4.00 ± 0.07; 6.00 ± 0.33 LD) and infected non treatment group (5.00 ± 0.13; 6.00 ± 0.24 LD) at 7, 14 days post infection respectively, while animals that intramammary treated with AgNPS expressed mild pathological lesions in mammary gland with few bacterial isolation (1.00 ± 0.05; 0.00 ± 0.00 LD) it was concluded that AgNPs expressed synergistic action with Ciprofloxacin against mastitis induced by E. coli O157:H7.