The antibacterial activity and selection of resistant bacteria, along with mechanisms of fluoroquinolone resistance, were investigated by integrating the static [MIC or mutant-prevention concentration (MPC)] and in vitro dynamic model approaches using Escherichia coli isolates from diseased dogs. Using the dynamic models, selected E. coli strains and enrofloxacin and marbofloxacin at a range of simulated area under concentration-time curve over a 24 h interval (AUC 24 h )/MIC ratios were investigated. Our results indicated increasing losses in susceptibility of E. coli upon continuous exposure to enrofloxacin and marbofloxacin in vitro. This effect was transferable to other fluoroquinolones, as well as to structurally unrelated drugs. Our results also confirmed an AUC 24 h /MIC (AUC 24 h /MPC)-dependent antibacterial activity and selection of resistant E. coli mutants, in which maximum losses in fluoroquinolone susceptibility occurred at simulated AUC 24 h /MIC ratios of 40-60. AUC 24 h /MPC ratios of 39 (enrofloxacin) and 32 (marbofloxacin) were considered protective against the selection of resistant mutants of E. coli. Integrating our MIC and MPC data with published pharmacokinetic information in dogs revealed a better effect of the conventional dosing regimen of marbofloxacin than that of enrofloxacin in restricting the selection of resistant mutants of E. coli. Target mutations, especially at codon 83 (serine to leucine) of gyrA, and overexpression of efflux pumps contributed to resistance development in both clinically resistant and in vitro-selected mutants of E. coli. We also report here a previously undescribed mutation at codon 116 of parC in two laboratory-derived resistant mutants of E. coli. Additional studies would determine the exact role of this mutation in fluoroquinolone susceptibility, as well as establish the importance of our findings in the clinical setting.

In the present study, a computational comparative and subtractive genomic/proteomic analysis aimed at the identification of putative therapeutic target and vaccine candidate proteins from Kyoto Encyclopedia of Genes and Genomes (KEGG) annotated metabolic pathways of Mycoplasma hyopneumoniae was performed for drug design and vaccine production pipelines against M.hyopneumoniae. The employed comparative genomic and metabolic pathway analysis with a predefined computational systemic workflow extracted a total of 41 annotated metabolic pathways from KEGG among which five were unique to M. hyopneumoniae. A total of 234 proteins were identified to be involved in these metabolic pathways. Although 125 non homologous and predicted essential proteins were found from the total that could serve as potential drug targets and vaccine candidates, additional prioritizing parameters characterize 21 proteins as vaccine candidate while druggability of each of the identified proteins evaluated by the DrugBank database prioritized 42 proteins suitable for drug targets.

The present study investigated the anti-inflammatory effects of dichloromethane extract of Auricularia auricula-judae. Dichloromethane extract of Auricularia auricula-judae inhibited Lipopolysaccharide (LPS) -induced nitric oxide (NO) production significantly in a dose-dependent manner in the concentration ≥10 μg/ml (p < 0.05) . Furthermore, RT-PCR results of this study indicated that the extract markedly reduced the expressions of inflammatory cytokines (IL-6, TNF-α and IL-1β) mRNA in LPS-treated murine RAW 264.7 macrophages, which could possibly ameliorate the inflammation. Nevertheless, dichloromethane extract of Auricularia auricula-judae did not show complete inhibition of IL-6 mRNA expression. The inhibition of IL-1β cytokine at protein level was also observed in a dose dependent manner. In conclusion,the current study revealed the previously unknown effect of dichloromethane ethyl extract of Auricularia auricula-judae inhibitions of the production of NO, IL-6, TNF-α and IL-1β in LPS-stimulated macrophages.

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