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Heba M Salem,1 Elshaimaa Ismael,2 Mohamed Shaalan3 1Department of Poultry Diseases, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt; 2Department of Veterinary Hygiene and Management, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt; 3Department of Pathology, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, EgyptCorrespondence: Mohamed ShaalanDepartment of Pathology, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, EgyptTel +20 1151854844Email mohamedibrahim@cu.edu.egBackground: Clostridium perfringens-associated necrotic enteritis (NE) is a serious problem affecting broiler production. A major global challenge is to reduce the use of antibiotics in poultry industry due to their negative impacts on public health. One alternative is to use nanoparticles (NPs) to overcome bacterial resistance to antibiotics. Silver nanoparticles (Ag NPs) showed strong antimicrobial activity.Methods: A total of 120 Cobb broiler chicks (1-day old) were obtained for this study and were divided into 4 equal groups at age of 14 days (30 birds each); each group was subdivided into 3 equal replicates (10 birds each). The groups were designated as follows: G1, infected; G2, infected and treated with Ag NPs; G3, treated with Ag NPs; and G4, negative control. Birds were infected with 4× 108 colony forming unit (CFU)/mL/bird C. perfringens type A for 2 successive days. In the treated groups, Ag NPs (mean diameter 15 nm; total dose 150 μg/bird) were administered via crop gavage. During the observation period (5 weeks), bird performance and immune organ indexes were recorded. Serum samples were collected for immunological evaluation, and tissue samples were collected for histopathology and estimation of Ag NPs residues.Results: Treatment with Ag NPs reduced the colonization of C. perfringens in the intestine and ceca, decreased the severity of clinical signs and reduced mortalities in comparison with infected non-treated group. Ag NPs treatment alleviated pathological lesions in the intestine and liver, but their residues were found in the muscles.Conclusion: Ag NPs have a positive impact on gut health integrity while having no impact on immune organs. Ag NPs have some residues in muscles; therefore, further studies are needed on the concentration and size of Ag NPs, the route of administration, and withdrawal time to ensure the safety of chicken meat for human consumption.Keywords: broiler chickens, Clostridium perfringens, FCR, histopathology, necrotic enteritis, residues, silver nanoparticles

Purpose The main objective of this study is to investigate the antibacterial activity of silver nanoparticles (AgNPs) against multidrug-resistant Salmonella isolates recovered from diarrheic sheep and goats. Methods This study used chemical reduction synthesis of AgNPs to evaluate their antimicrobial effects by estimation of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for each isolate using the microplate dilution method and tetrazolium salt reduction test to detect the viability percentage. In vivo treatment efficacy was assessed in mice by determining the viable count of Salmonella Enteritidis recovered from feces and by hematologic, biochemical and histopathologic examinations to confirm that use of AgNPs has no toxic or pathologic effects and to evaluate its ability in tissue regeneration following treatment. Results All recovered strains were identified as MDR with a prevalence of 4% and 3.6% in sheep and goats, respectively. The results of TEM, DLS, Zeta potential, and FTIR revealed typical characteristics of the synthesized AgNPs. Silver nanoparticles showed antibacterial activity against all recovered strains with MIC of ≤0.02-0.313 μg/mL (mean average 0.085±0.126 μg/mL) and MBC of 0.078-1.250 μg/mL (average 0.508±0.315 μg/mL). In vivo efficacy of AgNPs was observed by a reduction in the number of viable S. Enteritidis recovered from feces in an S. Enteritidis infected mouse model, with complete shedding stopping between treatment days 4 and 6. Hematologic, serum biochemical, and histopathologic analyses proved the ability of AgNPs to suppress inflammatory reaction caused by S. Enteritidis infection. Conclusion The study proved the effective ability of AgNPs to fight MDR Salmonella spp. in vitro and in vivo without adverse effects.