Minimum bactericidal concentration of chemically synthesized silver nanoparticles against pathogenic Salmonella and Shigella strains isolated from layer poultry farms

Abstract

The main objective of the present study is to find an appropriate in-vitro therapy to overcome clinically isolated antibiotic-resistant Salmonella and Shigella species from cases of layer poultry farms suffering from purulent dysentery and diarrhea. The present study demonstrated chemical synthesis of silver nanoparticles (AgNPs) via chemical reduction method and investigation for their antibacterial effect against the isolated bacteria by determining their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Of 32 examined samples, 8 (25%) antibiotic-resistant isolates were isolated and identified including: Shigella flexneri, Salmonella typhimurium (two), Salmonella poona, Shigella boydii, Salmonella montevideo, Shigella sonnei, Salmonella enteritidis. Spherical AgNPs of 10-25 nm in size were synthesized and the AgNPs at a concentration of 16 μgml -1 were found to have both bacteriostatic and bactericidal effects in the case of Salmonella montevideo (layer chicken egg), Shigella sonnei (layer chicken feces), Salmonella enteritidis (layer duck egg) however the AgNPs at a concentration of 8 μgml -1 were found to have both bacteriostatic and bactericidal effects in the case of Salmonella poona (layer chicken feces), Shigella boydii (layer chicken feces), Salmonella typhimurium (layer chicken feces).

Characterization of silver nanoparticles and evaluation of their antimicrobial effect on Salmonella

“…The shape, size, surface area and stability of Ag-NPs are deemed to be the main factors dictating bactericidal performance.Recent study (Omara et al, 2017) have shown results similar to those obtained in this study, in which reduced nanoparticle size may be related to the MICs. Flores et al 2013reported the effect of size on the MIC of Ag-NPs, where for 100 nm Ag-NPs the MIC was 104 μg•mL -1 , and for those of size 5-20 nm, 12-25 μg•ML -1 .…”

“…This fact indicates a different resistance profile among these, including between the two bacteria belonging to the Infantis serotype which showed contrast values. The MIC of 4.7 μg•mL -1 for Salmonella Enteritidis contrasts with the MIC of 16 μg•mL -1 for this same bacterium in a recent study by Omara et al (2017), which was approximately 4 times higher, whereas for S.…”

“…Use of antibiotics as bactericidal agents has been shown to have negative effects, such as high bacterial capacity to develop resistance and transfer resistance genes to other bacteria through plasmids, which is considered a major public health risk (Omara, Zawrah & Samy, 2017). Therefore, new treatments need to be studied as an alternative to antibiotic use.…”

“…In particular, Ag-NPs have gained importance as they present rapid methods of synthesis and characterization. Furthermore, they show antimicrobial activity against several microorganisms (Devi et al, 2017;Raman et al, 2017;Omara et al, 2017). The use of silvercontaining products is considered an alternative for controlling the emergence of resistant bacteria (He & Hwang, 2016).…”

<p><em>Shigella</em>: Antibiotic-Resistance Mechanisms And New Horizons For Treatment</p>

“…Omara et al tested AgNPs against pathogenic Salmonella and Shigella strains recovered from layer-poultry farms. AgNPs at a concentration of 16 μg/mL were found to have both bacteriostatic and bactericidal effects against Salmonella and Shigella isolates 171. Although NPs have shown high antibacterial activity during in -vitro and in -vivo experiments, future studies and judiciously performed clinical trials are required to achieve a better understanding of their potential side effects and clear regulatory guidelines.…”