The in vitro activity of danofloxacin plus ceftiofur combination: implications for antimicrobial efficacy and resistance prevention.

Due to the high prevalence of multi-drug resistant bacteria, combination therapy is an efficient choice for treatment of infections caused by highly resistant strains. In this study, the efficacy of ceftiofur plus danofloxacin combination was investigated against resistant Escherichia coli. The interaction between the two drugs was determined by checkerboard tests and time-kill assays. The combination was defined as bactericidal or bacteriostatic based on the minimum bactericidal concentration test results. Mutant prevention concentration test was used to evaluate the resistance tendency suppression potential of the combination. The combination had a synergistic effect against 83.00% of the isolates as verified by the checkerboard and time-kill assays. The combination was defined as bactericidal against all E. coli strains, since minimum bactericidal concentration: minimum inhibitory concentration ratios were below four thresholds and also markedly reduced mutant prevention concentration values of ceftiofur up to 4000-fold compared to its single use. Ceftiofur plus danofloxacin combination inhibited growth of E. coli strains which were resistant to ceftiofur or newer generation of fluoroquinolones. Our results suggest that ceftiofur plus danofloxacin combination has a bactericidal characteristic and can be an important alternative for the treatment of infections caused by resistant E. coli.

Structures and biochemical evaluation of silver(I) 5,5-diethylbarbiturate complexes with bis(diphenylphosphino)alkanes as potential antimicrobial and anticancer agents.

New silver(I) 5,5-diethylbarbiturate (barb) complexes with a series of bis(diphenylphosphino)alkanes such as 1,1-bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp) and 1,4-bis(diphenylphosphino)butane (dppb) were synthesized and characterized. [Ag2(barb)2(µ-dppm)2] (1), [Ag2(barb)2(µ-dppe)(DMSO)2] (2) and [Ag2(barb)2(µ-dppp)2] (3) were binuclear, while [Ag(barb)(µ-dppb)]n (4) was a coordination polymer. 1-4 effectively bind to the G/C rich region of the major groove of DNA and interact with BSA via hydrophobic interactions in accordance with molecular docking studies. All complexes displayed significant DNA cleavage in the presence of H2O2. 1-4 exhibited more specificity against Gram-positive bacteria than Gram-negative bacteria, but 2 targets both bacterial strains, being comparable to AgNO3 and silver sulfadiazine. Complex 1 has a strong growth inhibitory effect on A549 cells, while 2 and 3 exhibit considerable cytotoxicity against MCF-7 cells. The complexes showed high accumulation in the cytosol fraction of the cells. Mechanistic studies showed that 1 and 2 display effective cell growth inhibition by triggering S and G2/M phase arrest, induce apoptosis via mitochondrial pathways and also damage to DNA due to the overproduction of ROS.

Genotyping and antimicrobial resistance genes of Yersinia ruckeri isolates from rainbow trout farms.

In this study, we compared 142 Yersinia ruckeri isolates collected between 2013 and 2016 from 6 different regions in Turkey. A total of 18 different genogroups were found, though most of the isolates clustered into the same genogroup as serotype O1. As immunization of fish with inactivated Y. ruckeri by injection, immersion, or feeding provide minimal protection against Y. ruckeri infection in Turkey, many fish producers use antimicrobials unrestrictedly, resulting in antimicrobial resistance in aquatic pathogens. Accordingly, we investigated resistance to the antimicrobials most commonly used to treat yersiniosis. More than 80% of the Y. ruckeri isolates were susceptible to sulfamethoxazole-trimethoprim (SXT), florfenicol (FFC), and tetracycline, whereas none were susceptible to sulfamethoxazole. The most commonly used antimicrobials (SXT and FFC) can be effectively administered because the resistance levels to these drugs are the lowest among those reported for agents used to control enteric red mouth disease (12.6 and 14.7%, respectively). In conclusion, to the best of our knowledge, this study is the first characterization of the antimicrobial resistance genes floR, sulI, tetC, tetD, and tetE in Y. ruckeri isolates from aquaculture. Additionally, we detected the sulII gene but not the tetA, tetB, tetM, tetS, or sulIII genes.

Antioxidant and Antimicrobial Potential, and HPLC Analysis of Stictic and Usnic Acids of Three Usnea Species from Uludag Mountain (Bursa, Turkey).

In this study, antioxidant and antimicrobial potentials of Usnea intermedia, U. filipendula, and U. fulvoreagens and their stictic and usnic acid contents were investigated. Antioxidant activity and total phenolic contents were evaluated in acetone, ethanol, and methanol extracts of these three species. Antioxidant activity was measured by ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)] method and total phenolic contents were measured by Folin-Ciocalteu method. High-performance liquid chromatography (HPLC) was used for the determination of lichen acids. It can be concluded from stictic and usnic acids contents that the order of solvent efficiency is acetone > ethanol > methanol and acetone > methanol > ethanol, respectively. Broth microdilution method was performed to determine the minimum inhibitory concentration (MIC) of the methanol extracts of three Usnea species. The MIC values of all the extracts ranged from 64 µg/mL to 512 µg/mL for all the bacterial strains that were tested in this study, and all the Fluoro quinolone-resistant Escherichia coli isolates (except for E101) were sensitive to the methanol extracts of the three Usnea species. This paper is the first study to determine the stictic acid content in U. intermedia and U. filipendula. Our findings indicate that these three Usnea species could be used as antioxidant and antimicrobial agents.