Efficacy of fosfomycin compared to vancomycin in treatment of implant-associated chronic methicillin-resistant Staphylococcus aureus osteomyelitis in rats.

Fosfomycin monotherapy was compared to therapy with vancomycin for the treatment of implant-associated methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis in an experimental rat model. The proximal tibiae were inoculated with 15 µl of a suspension containing 1×10(8) to 5×10(8) CFU/ml of a clinical isolate of MRSA with simultaneous insertion of a titanium wire. Four weeks later, treatment was started for 28 days with either 50 mg/kg of body weight vancomycin intraperitoneally twice daily (n=11) or 75 mg/kg fosfomycin intraperitoneally once daily (n=10). Eleven animals were left untreated. After treatment, quantitative cultures from bone were found to be positive for MRSA in all animals in the untreated group (median, 3.29×10(6) CFU/g of bone) and the vancomycin group (median, 3.03×10(5) CFU/g of bone). In the fosfomycin group, MRSA was detectable in 2 out of 10 (20%) animals (3.42×10(2) and 1.51×10(3) CFU/g of bone). Vancomycin was superior to the no-drug control (P=0.002), and fosfomycin was superior to the no-drug control and vancomycin (P<0.001). The cultures from the wires were positive in all untreated animals (median, 2.5×10(3) CFU/implant), in 10 animals in the vancomycin group (median, 1.15×10(3) CFU/implant), and negative in all animals in the fosfomycin group. Based on the bacterial counts from the implants, vancomycin was not superior to the no-drug control (P=0.324), and fosfomycin was superior to the no-drug control and vancomycin (P<0.001). No emergence of resistance was observed. In conclusion, it was demonstrated that fosfomycin monotherapy is highly effective for the treatment of experimental implant-associated MRSA osteomyelitis.

Assessing pharmacokinetics of different doses of fosfomycin in laboratory rats enables adequate exposure for pharmacodynamic models.

Fosfomycin has been the subject of numerous pharmacodynamic in vivo models in recent years. The present study set out to determine fosfomycin pharmacokinetics in laboratory rats to enable adequate dosing regimens in future rodent models. Fosfomycin was given intraperitoneally as single doses of 75, 200 and 500 mg/kg bodyweight to 4 Sprague-Dawley rats per dose group. Blood samples were collected over 8 h and fosfomycin concentrations were determined by HPLC-mass spectrometry. Fosfomycin showed a dose-proportional pharmacokinetic profile indicated by a correlation of 0.99 for maximum concentration and area under the concentration-time curve (AUC). The mean AUC0-8 after intraperitoneal administration of 75, 200 or 500 mg/kg bodyweight fosfomycin were 109.4, 387.0 and 829.1 µg·h/ml, respectively. In conclusion, a dosing regimen of 200-500 mg/kg 3 times daily is appropriate to obtain serum concentrations in laboratory rats, closely mimicking human serum concentrations over time.

Penetration of doripenem into skeletal muscle and subcutaneous adipose tissue in healthy volunteers.

Sufficient antibiotic concentrations at the infection site are a prerequisite for good bacterial killing. This study was performed to determine pharmacokinetics of doripenem in soft tissues and saliva. Six healthy male volunteers received a single intravenous infusion of 500 mg doripenem over 1 h. The concentrations of doripenem were measured over 8 h in saliva, plasma, and extracellular space fluid of skeletal muscle and subcutaneous adipose tissue employing in vivo microdialysis. Unbound drug concentrations were determined using ultra-high-performance liquid chromatography-tandem mass spectrometry. Maximum concentrations of doripenem were 15.3 ± 6.0 mg/liter in plasma, 9.9 ± 2.3 mg/liter in subcutaneous adipose tissue, 6.6 ± 2.9 mg/liter in skeletal muscle, and 0.5 ± 0.2 mg/liter in saliva. Areas under the concentration-time curve (AUC) from 0 to infinity were 26.3 ± 10.1, 20.4 ± 3.8, 12.8 ± 3.0, and 1.0 ± 0.5 mg · h/liter in plasma, adipose tissue, skeletal muscle, and saliva, respectively. Ratios of AUC in adipose tissue, skeletal muscle, and saliva to those in plasma were 0.84 ± 0.28, 0.53 ± 0.19, and 0.04 ± 0.03, respectively. In all six volunteers, a threshold of ≥40% for "time above MIC," an index indicative of good antimicrobial activity, was exceeded in adipose tissue for MICs of ≤2 mg/liter and in skeletal muscle for MICs ≤1.5 mg/liter. Doripenem penetrates well into interstitial space fluid of skeletal muscle and adipose tissue, suggesting good antimicrobial activity in infected soft tissues, whereas it is detectable in relatively low concentrations in saliva.

Synergy study of the inhibitory potential of red wine polyphenols on vascular smooth muscle cell proliferation.

Vascular smooth muscle cell (VSMC) proliferation contributes to the development of atherosclerosis. Red wine consumption due to the polyphenol content has been reported to counteract atherosclerosis progression possibly through inhibition of VSMC proliferation, among other mechanisms. In this study we investigate the antiproliferative activity of four wine polyphenols: resveratrol, quercetin, ethyl gallate, and (+)-catechin in rat aortic VSMC. All four polyphenols inhibited serum-induced VSMC proliferation when applied as a single treatment. To further address a potential synergistic action of the investigated polyphenols, the antiproliferative effect of different combinations in equimolar, as well as equipotent ratios were quantified. The IC50 values of single polyphenols regarding the inhibition of VSMC proliferation ranged from 49.58 µM to 86.06 µM. However, apparent inhibitory efficacy of each compound increased by a factor of 10.4 in the quadruple equipotent mixture, as calculated from the dose-reduction index. Thus, the effective IC50 values of each of the four mixture constituents ranged from 4.76 µM to 8.27 µM. The calculated combination index (CI, where CI <, =, or > 1 indicate synergy, additivity, or antagonism, respectively) values of equimolar combinations of the polyphenols indeed indicated mainly synergy (CI ranging from 0.24 ± 0.01 to 1.51 ± 0.13). Optimized equipotent mixture showed enhanced synergy (CI ranging from 0.18 ± 0.04 to 1.36 ± 0.26). In conclusion, we show for the first time that four major polyphenols from wine synergistically inhibit VSMC proliferation.

Chemical and pharmacological investigations of Metaxya rostrata.

In a bioassay-guided approach the chemical composition of rhizomes of Metaxya rostrata (Kunth C. Presl) was studied for the first time. Investigations of the cytotoxicity of extracts and fractions on SW480 colorectal carcinoma cells resulted in the isolation of two polyphenols--cinnamtannin B-1 and aesculitannin B. The structures of the compounds were elucidated by different NMR experiments. Additionally, sugars, common sterols, such as sitosterol, stigmasterol and campesterol, as well as chlorogenic acid and caffeic acid were identified in Metaxya rostrata.

Modulation of bacterial ghosts--induced nitric oxide production in macrophages by bacterial ghost-delivered resveratrol.

The present study aimed to investigate the capacity of resveratrol (RV) delivered into macrophages by bacterial ghosts (BGs), representing intact empty nonliving envelopes of Gram-negative bacteria, to modulate nitric oxide (NO) production related to the presence of the pathogen-associated molecular patterns on the surface of BGs. Incubation of the murine macrophage cell line RAW 264.7 with BGs leads to a dose-dependent activation of inducible NO synthase. To modify BG-induced NO formation in RAW 264.7 cells by RV; BGs were loaded with RV (RV-BGs) and incubated with murine macrophages in a dose-dependent manner. RV-BGs delivering RV to the target macrophages significantly reduced BG-induced NO production with concentration of RV more than one order of magnitude lower than the amount of RV capable of reducing NO formation when applied directly. Moreover, no cytotoxic impact of BGs on the viability of RAW 264.7 cells added to macrophages alone or loaded with RV was detected after a mutual 24 h incubation, whereas cell viability slightly decreased (~ 10%) when RV concentrations of 30 µm alone were applied. The results obtained in the present study clearly indicate that the intracellular delivery of RV by BGs significantly enhances the total RV effect.

Penetration of doripenem in human brain: an observational microdialysis study in patients with acute brain injury.

Concentration-time profiles of unbound doripenem were determined by microdialysis in the cerebral interstitium of five patients with acute brain injury. The ratio of the area under the concentration-time curve in brain to that in plasma (AUC(brain)/AUC(plasma)) was 0.17 in one patient and 0.01 in the remaining four patients. Based on the percentage of the dosing interval during which the doripenem concentration exceeded a certain minimum inhibitory concentration (T>MIC), a value of ≥35% of the dosing interval was reached for pathogens with MICs up to 0.05 mg/L. The present data indicate that breakpoints based on concentrations of doripenem in plasma may overestimate antimicrobial activity in brain parenchyma.

Two Unusual Methylidenecyclopropane Glucosides from Metaxya rostrata C.Presl.

Two new natural compounds, (1R,2E)-2-(6-hydroxyhexylidene)cyclopropyl-ß-D-glucopyranoside (1) and (6E)-6-[(2R)-2-(ß-D-glucopyranosyloxy)cyclopropylidene]hexanoic acid (2), glucosides of a very rare methylidenecyclopropane alcohol, as well as two known glycosides of phenolic acids, namely 4-O-ß-D-glucopyranosylcaffeic acid (3) and (E)-4-O-ß-D-glucopyranosylcoumaric acid (4), and methyl α-fructofuranoside (5) were isolated for the first time from the rhizomes of the tree fern Metaxya rostrata C.Presl. The structures were elucidated on the basis of detailed spectroscopic data analysis, and the structure of 1 was additionally confirmed by X-ray crystal-structure analysis.