sitafloxacin and Disease-Models--Animal

Eradication of MRSA osteomyelitis requires elimination of distinct biofilms. To overcome this, we developed bisphosphonate-conjugated sitafloxacin (BCS, BV600072) and hydroxybisphosphonate-conjugate sitafloxacin (HBCS, BV63072), which achieve "target-and-release" drug delivery proximal to the bone infection and have prophylactic efficacy against MRSA static biofilm in vitro and in vivo. Here we evaluated their therapeutic efficacy in a murine 1-stage exchange femoral plate model with bioluminescent MRSA (USA300LAC::lux). Osteomyelitis was confirmed by CFU on the explants and longitudinal bioluminescent imaging (BLI) after debridement and implant exchange surgery on day 7, and mice were randomized into seven groups: 1) Baseline (harvested at day 7, no treatment); 2) HPBP (bisphosphonate control for BCS) + vancomycin; 3) HPHBP (hydroxybisphosphonate control for HBCS) + vancomycin; 4) vancomycin; 5) sitafloxacin; 6) BCS + vancomycin; and 7) HBCS + vancomycin. BLI confirmed infection persisted in all groups except for mice treated with BCS or HBCS + vancomycin. Radiology revealed catastrophic femur fractures in all groups except mice treated with BCS or HBCS + vancomycin, which also displayed decreases in peri-implant bone loss, osteoclast numbers, and biofilm. To confirm this, we assessed the efficacy of vancomycin, sitafloxacin, and HBCS monotherapy in a transtibial implant model. The results showed complete lack of vancomycin efficacy while all mice treated with HBCS had evidence of infection control, and some had evidence of osseous integrated septic implants, suggestive of biofilm eradication. Taken together these studies demonstrate that HBCS adjuvant with standard of care debridement and vancomycin therapy has the potential to eradicate MRSA osteomyelitis.

Topics: Animals; Anti-Bacterial Agents; Disease Models, Animal; Methicillin; Methicillin Resistance; Methicillin-Resistant Staphylococcus aureus; Mice; Osseointegration; Osteomyelitis; Staphylococcal Infections; Vancomycin

Topics: Animals; Anti-Bacterial Agents; Diphosphonates; Disease Models, Animal; Fluoroquinolones; Methicillin-Resistant Staphylococcus aureus; Mice; Osteomyelitis; Staphylococcal Infections; Staphylococcus aureus; Tissue Distribution; Vancomycin

DS-8587 is a novel parenteral fluoroquinolone, which has an activity equivalent to sitafloxacin against various pathogens including anaerobes. We examined the in vivo anti-anaerobic activity of DS-8587, and compared it with that of levofloxacin (LVFX), using a murine model of Fusobacterium necrophorum-induced liver abscess developed via blood borne infection. Mice with liver abscess infection caused by F. necrophorum were treated with saline (control), DS-8587 (0.8, 4, and 20 mg/kg twice daily), or LVFX (20 and 100 mg/kg) for a day. After treatment, the number of viable bacteria in liver was analyzed. We also analyzed the pharmacokinetics of these agents in plasma and the liver after initial treatment. The MICs of DS-8587 and LVFX were 0.015 and 1 mg/mL, respectively. DS-8587 eradicated the viable bacteria in the liver even at doses as low as 4 mg/kg. In contrast, the liver bacteria were not eradicated in any of the LVFX-treated mice even at a dose of 100 mg/kg (P < 0.05 compared with DS-8587, 4 or 20 mg/kg). The pharmacokinetic parameter AUC/MIC ratios for DS-8587 (4 mg/kg) and LVFX (100 mg/kg) were 96.7 and 60.8 in plasma and 600 and 145.6 in the liver, respectively. The AUC/MIC ratio showed the best correlation with efficacy of DS-8587. DS-8587 significantly reduced the number of viable bacteria in a murine model of F. necrophorum-induced liver abscess compared to LVFX. Our study demonstrated that the anti-anaerobic activity of quinolones in vivo was different from the MICs in vitro.

Topics: Animals; Bacteria, Anaerobic; Disease Models, Animal; Fluoroquinolones; Fusobacterium necrophorum; Levofloxacin; Liver; Liver Abscess; Male; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests

Antibiotic activity can differ depending on whether the bacterial target is extracellular or intracellular. To determine extracellular and intracellular activities of sitafloxacin (STX) against Staphylococcus aureus in comparison with levofloxacin (LVX) and moxifloxacin (MXF) in vivo and in vitro, three S. aureus strains (ATCC25923, 29213, 43300) were evaluated. MIC, MBC and mutant prevention concentration (MPC) of the test quinolone for S. aureus were determined by microdilution in broth, and intracellular activity was determined in RAW264.7 cells after phagocytosis of bacteria. Cellular quinolone accumulation was determined by HPLC. The time- and concentration-kill relationships were examined in vitro (in broth and in RAW264.7 cells, respectively) and in vivo by use of a mouse peritonitis model. The results showed that the activity of STX in broth cultures, including the MIC, MBC, MPC and the time- and concentration-kill relationships, were greater for STX than those for LVX and MXF. In particular, STX exhibited the strongest activity against intramacrophage S. aureus. The intracellular effects could be ranked in the following order as the mean change in the log10 number of cfu ml(-1) (log10 cfu ml(-1)) between treated and untreated mice: STX>LVX>MXF. It also showed that the dominant factor of intracellular activity in vivo was the frequency of doses. There was a poor correlation between the intracellular accumulation of the three different quinolones and the actual intracellular effect. The results of the intracellular and extracellular time- and concentration-kill relationships indicated that STX has the potential to display useful activity against extracellular and intracellular S. aureus.

Topics: Animals; Anti-Bacterial Agents; Aza Compounds; Cell Line; Chromatography, High Pressure Liquid; Disease Models, Animal; Dose-Response Relationship, Drug; Extracellular Space; Fluoroquinolones; Intracellular Space; Levofloxacin; Mice; Mice, Inbred ICR; Microbial Sensitivity Tests; Moxifloxacin; Ofloxacin; Peritonitis; Quinolines; Staphylococcal Infections; Staphylococcus aureus; Time Factors

A novel murine model of non-typeable Haemophilus influenzae (NTHi) pneumonia was established. A plastic tube was inserted into the trachea 7 days before bacterial inoculation. Numbers of NTHi recovered from the lungs and trachea were determined for 7 days. Histologically, bronchioles and adjacent alveoli in the intubation group were filled with numerous inflammatory cells. The efficacy of sitafloxacin was compared with ciprofloxacin using the new murine pneumonia model. The data suggest that sitafloxacin displays equivalent efficacy to ciprofloxacin against H. influenzae pneumonia. This new murine NTHi pneumonia model appears useful not only for in vivo evaluation of antibiotics but also for analysis of the pathogenesis of H. influenzae pneumonia.

Topics: Animals; Anti-Bacterial Agents; Bronchioles; Ciprofloxacin; Disease Models, Animal; Fluoroquinolones; Haemophilus Infections; Haemophilus influenzae; Intubation, Intratracheal; Male; Mice; Pneumonia, Bacterial; Pulmonary Alveoli; Time Factors; Trachea; Treatment Outcome

The proarrhythmic effects of fluoroquinolone antibacterial agents, sitafloxacin, gatifloxacin and moxifloxacin, were compared using three in vivo models. In the halothane-anesthetized dogs (n=5), intravenous 10-min infusion of gatifloxacin and moxifloxacin (1-3 mg/kg) prolonged the ventricular effective refractory period and the repolarization period to a similar extent, whereas sitafloxacin (1-3 mg/kg) prolonged the former only. No significant change was detected in other cardiovascular parameters. In the chronic complete atrioventricular block dogs (n=4), oral administration of 100 mg/kg of gatifloxacin (2 of 4) and moxifloxacin (3 of 4) induced torsades de pointes, which was not observed by sitafloxacin. In the alpha-chloralose-anesthetized rabbits (n=5), intravenous 20-min infusion of 60 mg/kg of gatifloxacin induced torsades de pointes (1 of 5) in the presence of methoxamine infusion, which was not observed by sitafloxacin or moxifloxacin. Thus, the halothane-anesthetized model is suitable for assessing QT prolongation, whereas the chronic complete atrioventricular block model is sensitive for detecting torsadogenic action of drugs. The alpha-chloralose-anesthetized model is the simplest and least expensive method, but its sensitivity to detect proarrhythmic action may be less great.

Topics: Administration, Oral; Animals; Aza Compounds; Blood Pressure; Chloralose; Disease Models, Animal; Dogs; Electrocardiography; Female; Fluoroquinolones; Gatifloxacin; Halothane; Heart Block; Heart Rate; Infusions, Intravenous; Long QT Syndrome; Male; Moxifloxacin; Quinolines; Rabbits; Risk Assessment; Time Factors; Torsades de Pointes; Ventricular Function, Left

Efficacy of a new fluoroquinolone, sitafloxacin (DU-6859a), against Mycobacterium ulcerans was evaluated in vivo using the mouse footpad system. The growth of M. ulcerans in mouse footpads was completely inhibited when mice were fed with sitafloxacin at a dose of 25 mg/kg body weight per day; on the other hand similar effects were observed with ofloxacin at a dose of 100 mg/kg body weight per day. In the presence of rifampin, the above dose of sitafloxacin could be reduced by 75% to achieve total inhibition, while, under similar circumstances, the dose of ofloxacin could be reduced by only 50%. Either used singly or in combination with rifampin, the effects of sitafloxacin were bactericidal. The results suggest that sitafloxacin should be evaluated as a chemotherapeutic agent against M. ulcerans infection.

Topics: Animals; Anti-Infective Agents; Antibiotics, Antitubercular; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Therapy, Combination; Female; Fluoroquinolones; Foot; Mice; Mice, Inbred BALB C; Mycobacterium Infections, Nontuberculous; Mycobacterium ulcerans; Rifampin

We evaluated the efficacy of a new quinolone, DU-6859a, using a new model of rat uterine endometritis. Rats were infected with mixed inocula of Escherichia coli and Bacteroides fragilis. The MICs of DU-6859a and levofloxacin against E. coli were 0.025 and 0.05 mg/L, respectively; those against B. fragilis were 0.20 and 0.39 mg/L, respectively. Immediately after inoculating 10(5) cfu/rat of each organism, DU-6859a or levofloxacin (20 mg/kg po bid or tid, respectively, for 3 days) was administered and compared with the untreated group. The viable cell counts of E. coli and B. fragilis in the DU-6859a- and levofloxacin-treated groups were significantly lower than those in the untreated group. These results suggest that DU-6859a would be useful for treating polymicrobial infections in uterine endometritis.

Topics: Animals; Anti-Infective Agents; Bacteroides fragilis; Disease Models, Animal; Drug Therapy, Combination; Endometritis; Escherichia coli; Female; Fluoroquinolones; Levofloxacin; Ofloxacin; Quinolones; Rats; Rats, Sprague-Dawley