الفهرس 
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Abstract
The current study was designed to investigate the different internal organs of 247 infected birds with gastroenteritis manifestations in different poultry farms for isolation and identification of Salmonella species. The internal organs of infected birds were divided into two groups including heart, liver and spleen that collected as (one group) while caecum collected as (another group). Then, serological identification of 70 Salmonella isolates was performed. In addition, an overview for recognition to the pathogenicity of 12 different resistant Salmonella serotypes through detection of their virulence genes (invA, fimH, stn and pefA genes). Besides the antimicrobial activity of Salmonella species was assessed using the antibacterial agents alone, essential oils and essential oils nano-emulsion. In addition, the activity of combined essential oils or essential oils nano-emulsion with antimicrobial agents. Moreover, preparation then characterization of essential oils nano-emulsion using FT-IR and TEM was performed to confirm the formation of oils nano-emulsion.
A total of 72 different poultry farms (50 chicken, 16 chick, three duck and three duckling) were investigated to detect the prevalence of salmonellosis among the examined farms. The prevalence of Salmonellae was observed in twenty-three examined farms (ten chicken, nine chick, one duck and three duckling farms), whereas a total prevalence rate was 31.94% in all investigated farms besides the prevalence in different farms was 20, 56.25, 33.33 and 100%, respectively.
The serological identification of Salmonella isolates showed 14 variable serotypes (S. Virchow; S. Anatum; S. Rechovot; S. Enteritidis; S. Salamae/ O6, 7: m, t; S. Salamae/ O6,7: g,m, {s}, t: e, n, x; S. Kedougou; S. Lumberhurst; S. Typhimurium; S. Fillmore; S. Montevideo; S. Paratyphi C; S. Infantis and S. Nanga). All recorded Salmonella serovars were recovered from heart, liver, and spleen with high prevalence rates to S. Virchow, S. Anatum and S. Infantis represented by 17.14, 11.43 and 11.43% in order. In contrast, the highest prevalence rate of Salmonella serovars obtained from caecum were S. Infantis, S. Virchow and S. Paratyphi C (14.29, 14.29 and 11.43%, respectively).
Furthermore, genotypic identification of twelve different Salmonella serotypes using PCR. InvA, fimH and stn virulence genes were detected in all Salmonella serovars at 100% meanwhile, pefA gene was only found in S. Typhimurium and S. Lumberhurst that indicating their higher pathogenicity at a prevalence rate of 16.67%.
Regarding to the antimicrobial profile of Salmonella spp. isolates, the highest sensitivity percentage was detected using disc diffusion method. The sensitivity of Salmonella spp. isolates to amikacin, piperacillin-tazobactam, cefoxitin and amoxicillin-clavulanic acid was 97.14, 95.71, 90.0, and 90.0%, respectively. Otherwise, their sensitivity to ampicillin, chloramphenicol and gentamicin was 47.14, 40.0, and 31.43% in order. Moreover, multidrug resistance was observed in 50% of Salmonella isolates.
The minimum inhibitory concentration (MIC) of essential oils: (thymol, carvacrol, basil and cinnamon oils) against 70 Salmonella spp. isolates was detected using agar dilution method. The MIC of thymol oil was found at 0.01% concentration with a prevalence rate of 1.43%. On the other hand, The MIC of cinnamon was identified at 0.01% concentration with a prevalence rate of 11.43%. Whereas the MIC of basil oil was found at 0.1% concentration with a prevalence rate of 17.14%. Furthermore, The MIC of carvacrol was detected at 0.01% concentration with a prevalence rate of 34.29%.
The effect of combined essential oils with antibacterial agents was recognized. The sensitivity pattern of resistant Salmonella isolates was enhanced against cefazolin, chloramphenicol, gentamicin, cefotaxime, ampicillin, tobramycin and aztreonam at 100, 95.71, 91.43, 90.0, 87.14, 87.14 and 81.43% in descending manner after using thymol oil at 0.001% concentration. Furthermore, after using carvacrol 0.001%, all resistant Salmonellae to gentamicin, tobramycin, chloramphenicol, cefazolin and aztreonam transformed into sensitive. On the other hand, only 11.43% and 7.14% of Salmonella isolates were still resistant to ampicillin (47.14%) and cefotaxime (21.43%) respectively. In addition, Complete enhanced effect of using basil oil 0.01% to resistant Salmonellae in presence of gentamicin, tobramycin, chloramphenicol, and cefazolin at 100% prevalence rate. In contrast, using basil oil 0.01% with aztreonam (25.71%), cefotaxime (21.43%) and ampicillin (47.14%) enhanced the susceptibility patterns of resistant Salmonella isolates by 80.0, 82.86 and 88.57% in order. Additionally, all resistant Salmonella isolates (100%) were enhanced in their susceptibility patterns against gentamicin, tobramycin, chloramphenicol, and cefazolin after using cinnamon oil 0.001%. Meanwhile, aztreonam (25.71%), ampicillin (47.14%) and cefotaxime (21.43%) showed sensitive patterns at 78.57, 88.57 and 90.0% in ascending manner after using 0.001% cinnamon oil against resistant Salmonella isolates.
Essential oils nano-emulsions were characterized by FT-IR that showed different characteristic peaks. FT-IR spectra of thymol nano-emulsion clarified the widened and smooth peak was noticed at 3331.25 cm−1. Meanwhile, FT-IR spectra of carvacrol nano-emulsion exhibited the characteristic peaks appeared at 3333.92, 1646.56, 1043.12, and 625.92 cm−1. On the other hand, basil essential oil nano-emulsion showed variable peaks at 3379.45, 2923.95, 1514.98, 914.22, and 687.01 cm−1. Moreover, FT-IR spectra of cinnamon oil nano-emulsion showed the wide peak that appeared at 3350.96, 1647.34, 1047.06, and 619.77 cm−1. Concerning to using HR-TEM in detection of shape and size of nano-emulsion, thymol nano-emulsion showed spherical particles distributed in the TEM field. On the opposite side, the average diameter of nanoparticles is ranged from 24.02 to 54.0 nm. Furthermore, the TEM image of carvacrol nano-emulsion showed the nanoparticles of spherical shape scattered into the nano-emulsion and the average size of nanoparticles is ranged from 30 to 130 nm. TEM microscopy of basil nano-emulsion displayed the spherical and ovoid shape of NPs scattered in the field of TEM with the average size is ranged from 38.72 to 65.59 nm. Finally, TEM microscopy of cinnamon nano-emulsion presented very fine spherical NPs in shape and had a raised surface besides the NPs size is ranged from 53.21 to 54.30 nm in diameter.
Applying nano-emulsion of essential oils on Salmonellae had no inhibitory effect on their growth. Whilst conjugation of oils nano-emulsion with antibacterial agents enhanced the antimicrobial effect on resistant Salmonellae with variable degrees. After exposure of resistant Salmonella isolates to thymol oil nano-emulsion at 0.01% in presence of cefotaxime, aztreonam and ampicillin, we found that the sensitivity pofile was enhanced at 100, 83.33, and 0%, respectively. Additionally, after exposure to carvacrol oil nano-emulsion 0.01% in presence of cefotaxime, aztreonam and ampicillin, the sensitivity of resistant Salmonella isolates was enhanced at 100, 76.92, and 0%, respectively. Moreover, after exposure of resistant Salmonella isolates to basil oil nano-emulsion 0.1% in presence of cefotaxime, and aztreonam the sensitivity pattern was enhanced at 100, and 71.43, respectively. In addition, resistant Salmonella isolates after exposure to cinnamon oil nano-emulsion 0.01% in presence of cefotaxime, and aztreonam, the sensitivity profile was enhanced at 100, and 76.92%, respectively.