Synergistic Effect of Silver Nanoparticles with Neomycin or Gentamicin Antibiotics on Mastitis-Causing <i>Staphylococcus aureus</i>

Abstract

Objective: Mastitis is one of the most costly diseases in dairy cows, which greatly decreases milk production. Use of antibiotics in cattle leads to antibiotic-resistance of mastitis-causing bacteria. The present study aimed to investigate synergistic effect of silver nanoparticles (AgNPs) with neomycin or gentamicin antibiotic on mastitis-causing Staphylococcus aureus. Materials and Methods: In this study, 46 samples of milk were taken from the cows with clinical and subclinical mastitis during the august-October 2015 sampling period. In addition to biochemical tests, nuc gene amplification by PCR was used to identify strains of Staphylococcus aureus. Disk diffusion test and microdilution were performed to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Fractional Inhibitory Concentration (FIC) index was calculated to determine the interaction between a combination of AgNPs and each one of the antibiotics. Results: Twenty strains of Staphylococcus aureus were isolated from 46 milk samples and were confirmed by PCR. Based on disk diffusion test, 35%, 10% and 55% of the strains were respectively susceptible, moderately susceptible and resistant to gentamicin. In addition, 35%, 15% and 50% of the strains were respectively susceptible, moderately susceptible and resistant to neomycin. According to FIC index, gentamicin antibiotic and AgNPs had synergistic effects in 50% of the strains. Furthermore, neomycin antibiotic and AgNPs had synergistic effects in 45% of the strains. Conclusion: It could be concluded that a combination of AgNPs with either gentamicin or neomycin showed synergistic antibacterial properties in Staphylococcus aureus isolates from mastitis. In addition, some hypotheses were proposed to explain antimicrobial mechanism of the combination.

Combined efficacy of silver nanoparticles and commercial antibiotics on different phylogenetic groups of Escherichia coli

“…The results obtained from this study are consistent with that of other researches. Indeed, gentamycin plus Ag-NPs in several studies demonstrated enhanced or even synergistic antibacterial effect against (Barapatre, et al 2016;Chhibber, et al 2017;Ebrahimi, et al 2017;Jamaran and Zarif 2016;Katva, et al 2017;Mohamed, et al 2017;Panacek, et al 2015;Satapathy, et al 2017;Verma, et al 2017;Wang, et al 2016).Moreover, in a good agreement with reported data in the literature, penicillin (Ebrahimi, et al 2017;Panacek, et al 2015) in contrary to some studies (Deng, et al 2016;Natan and Banin 2017;Wang, et al 2016) and ciprofloxacin in the case of human strains (Mohamed, et al 2017;Yallappa, et al 2015) in accord with our data (Panacek, et al 2015) showed significant increase in antibacterial activities when conjugated with Ag-NPs. Furthermore, tetracycline (Deng, et al 2016;Ebrahimi, et al 2017;Natan and Banin 2017), amoxicillin (Mohamed, et al 2017), cephalosporin (Refat, et al 2017), erythromycin (Yallappa, et al 2015 showed partially increase in antibacterial activities in the presence of Ag-NPs.…”

Application of some nanoparticles in the field of veterinary medicine

“…Gentamicin and neomycin are hydrophilic however silver nanoparticles are hydrophobic. For this reason, silver nanoparticle in contrast to antibiotics can easily bypass cellular membrane and reach to the target cell effectively [134].…”

Nanoparticles for treatment of bovine Staphylococcus aureus mastitis

“…Throughout the previous years, much anxiety has been raised regarding the treatment failure. Consequently, continual attention has given by the researchers to discover new strategies for treatment (Dehkordi et al, 2011;Jamaran & Zarif, 2016). Recently, nano drugs have been used as a substitute measure to solve the multi-drug resistance and intracellular persistence of S. aureus which associated with the subclinical and relapsing infection of bovine mastitis (Le Ray et al, 2005;Franci et al, 2015;Wang et al, 2017;…”