ABSTRACT
A novel, functionalized graphene oxide-based cellulose acetate membrane was fabricated using the phase inversion method to improve the membrane characteristics and performance. We studied the effect of aminated graphene oxide (NH2-GO) composite on the CA membrane characteristics and performance in terms of membrane chemistry, hydrophilicity, thermal and mechanical stability, permeation flux, and antibacterial activity. The results of contact angle and water flux indicate the improved hydrophilic behavior of composite membranes in comparison to that of the pure CA membrane. The AGO-3 membrane showed the highest water flux of about 153 Lm-2h-1. The addition of hydrophilic AGO additive in CA membranes enhanced the antibacterial activity of AGO-CA membranes, and the thermal stability of the resulting membrane also improved since it increases the Tg value in comparison to that of a pristine CA membrane. The aminated graphene oxide (NH2-GO) was, therefore, found to be a promising additive for the fabrication of composite membranes with potent applications in wastewater treatment.
ABSTRACT
The purpose of this study was to investigate the prevalence, antibiotic resistance and certain virulence genes of the most predominant bacterial pathogens causing BRD. A total of 225 calves; 55 apparently healthy and 170 diseased; were sampled. Bacteriological examination, antimicrobial susceptibility testing and PCR based detection of some virulence genes were performed. In addition, the serotyping of E. coli was performed using the slide agglutination test. The most predominant bacterial pathogens retrieved from apparently healthy calves were E. coli (16.4%) and S. aureus (10.9%), and in pneumonic calves were E. coli (23.5%), P. vulgaris (12.4%) and S. aureus (11.8%). The most prevalent virulence gene in E. coli was the fimH gene (100%), followed by eaeA gene (24.5%) and hly gene (20.4%). All the examined S. aureus strains harbored spa and coa genes; likewise, all P. multocida strains harbored toxA gene. The majority of the isolated strains displayed remarkable sensitivity to norfloxacin and enrofloxacin; furthermore, the retrieved E. coli strains exhibited multidrug-resistance to gentamicin, erythromycin, streptomycin and trimethoprim-sulphamethoxazole, in addition, the isolated S. aureus and P. aeruginosa strains showed multidrug-resistance to amoxicillin, ampicillin and tetracycline. E. coli serogroups including O18, O143, O1, and O6 were retrieved from pneumonic calves as the first report in Egypt. In conclusion, the synergism between the conventional and genotypic analysis is an effective gadget for the characterization of bacterial pathogens causing BRD. Continuous surveillance of antimicrobial susceptibility is essential to select the drug of choice due to the development of multidrug-resistant strains.
