Tissue concentrations of vancomycin and Moxifloxacin in periprosthetic infection in rats.

BACKGROUND: A one-step exchange of an endoprosthesis with periprosthetic infection requires effective antibiotics at high concentrations around the endoprosthesis. We evaluated the tissue distribution of vancomycin and Moxifloxacin in a standardized in vivo model of periprosthetic infection. METHODS: 36 male rats with periprosthetic infection of the left hind leg, induced by a standardized procedure, received either antibiotic treatment with vancomycin or Moxifloxacin twice daily for 2 weeks, or a sham treatment. After the last administration, different tissues from each animal were evaluated for concentrations of antibiotic. RESULTS: Compared to plasma, the tissue concentrations of Moxifloxacin were higher in all tissues investigated (lung, muscle, fat, bone) and the tissue-plasma ratio of Moxifloxacin was considerably higher than that of vancomycin. The concentrations of Moxifloxacin were equally high in the infected and the uninfected hind leg, whereas the vancomycin concentrations were significantly higher in the infected leg. INTERPRETATION: The standardized model of periprosthetic infection described here can be extrapolated to different bacterial and mycotic pathogens, and also to different antibiotics or therapeutic regimes. It provides a way of correlating tissue concentrations with clinical outcome in future studies.

Moxifloxacin superior to vancomycin for treatment of bone infections--a study in rats.

BACKGROUND: Increasing resistance rates towards conventional antibiotics necessitate investigations of the efficacy of newly developed antibiotics. Thus, in a rat study, we compared the efficacy of moxifloxacin and vancomycin in the treatment of a local Staphylococcus aureus bone infection. METHOD: The femoral medullary cavities of 36 Wistar rats were contaminated with 100 muL of an oxacillin-sensitive Staphylococcus aureus strain (ATCC 29213) at 10(8) cfu/mL. On the seventh day, antibiotic treatment with moxifloxacin (10 mg/kg twice daily i.p.) or vancomycin (15 mg/kg twice daily i.p.) was commenced in 12 animals each. 12 control animals were left untreated. After 21 days, the infected femurs were explanted and the bacterial counts (cfu/g) were determined. RESULTS: In the control group, a median of 3.42 x 10(6) cfu/g (LQ/UQ 1.09 x 10(6)/ 1.55 x 10(7)) was cultured, with a median of 2.53 x 10(6) cfu/g (LQ/UQ 1.95 x 10(6)/ 4.25 x 10(6)) in the vancomycin group and a median of 2.49 x 10(5) cfu/g (LQ/UQ 2.84 x 10(4)/ 3.75 x 10(5)) in the moxifloxacin group. The bacterial count was reduced by treatment with moxifloxacin both in comparison with the control group (p < 0.001), and in comparison with treatment with vancomycin (p < 0.001). There was no statistically significant difference between the vancomycin group and the control group (p = 0.53). INTERPRETATION: In contrast to vancomycin, moxifloxacin proved to be an effective antibiotic for the treatment of bone infections due to Staphylococcus aureus in our animal model.

Treatment of implant-associated infections with moxifloxacin: an animal study.

The efficacy of moxifloxacin in the treatment of an implant-associated infection by Staphylococcus aureus was compared with vancomycin in an animal study. The femoral medullary cavity of 36 Wistar rats was contaminated with S. aureus (ATCC 29213) and a metal device was implanted. After treatment for 14 days with moxifloxacin (2 x 10 mg/kg/day) or vancomycin (2 x 15 mg/kg/day), the bacterial counts (colony-forming units) in the periprosthetic bone, the soft tissue and the implant-associated biofilm were measured. Compared with the control group, moxifloxacin achieved a highly significant decrease in the microbial counts in the bone and soft tissue and in the biofilm (P<0.001). Moreover, the efficacy of moxifloxacin was significantly greater than that of vancomycin (P<0.01). Vancomycin did not reduce the microbial count significantly compared with the control group (P>0.05). The results justify further investigations of the treatment of implant-associated infections due to S. aureus with moxifloxacin.

Proposal for a sonographic classification of target joints in rheumatoid arthritis.

OBJECTIVE: The purpose of this study was to classify sonographically the joint damage of target joints in patients with rheumatoid arthritis (RA). METHODS: During a 3-year cross-sectional study, standardized arthrosonography of symptomatic target joints was performed in patients with RA. According to those findings, a classification with progressive deterioration of joint alteration in RA was created that grades visible morphological changes of the joint components. Using elbow joints as a subgroup, inter- and intraobserver reliability was calculated. RESULTS: Examined and included in this study were 1211 joints of 425 patients with RA. The mean disease activity score was 5.2 (range 0.75-7.79). Sonographically visible changes could be classified and divided into six stages. A standardized sonographic evaluation system was developed. In reference to the elbow joint, overall percentages for intra- and interobserver reliability of sonography were 90.8% and 88.8%, respectively. CONCLUSION: Sonography is a valuable tool for assessing and classifying joint alteration in RA. Particularly in early stages of joint affection, ultrasound is superior to X-ray in detecting soft tissue changes and minor erosions.

Amorphous silicon, flat-panel, x-ray detector: reliability of digital image fusion regarding angle and distance measurements in long-leg radiography.

RATIONALE AND OBJECTIVES: To evaluate composed long-leg images acquired with a large-area, flat-panel x-ray detector with regard to angle and distance measurements. METHODS: Radiographs of a long-leg phantom were acquired at 13 different angle settings with a 43-cm x 43-cm digital x-ray detector based on cesium iodide (CsI) and amorphous silicon (a-Si) technology. Three overlapping single images of the phantom were reconstructed at a workstation using a generalized correlation method. Four blinded observers were instructed to determine the angle of the axis of the long-legs as well as the length of "femur" and "tibia" on soft-copy displays. For that, the angle and distance measurement software integrated in the workstation was used. The images were analyzed with and without prior manual fine tuning of the primary composition result according to a mapped scale. Standard of reference was angle and distance determination at the phantom. RESULTS: On average, the difference between the observers' angle measurements and the standard of reference was 0.4 degrees for both images with and without prior manual correction. Regarding distance measurements, the average discrepancies to the standard were 0.2 cm (femur) and 0.1 cm (tibia) when analyzing images that had undergone manual fine tuning and 0.5 cm and 0.7 cm, respectively, for images without manual correction. CONCLUSIONS: The evaluated image fusion algorithm in conjunction with a 43-cm x 43-cm flat-panel detector is feasible regarding angle and distance measurements on long-leg images. In the case of inaccurate primary composition, results can be corrected easily by manual fine tuning.

Navigation-assisted, minimally invasive implant removal following a triple pelvic osteotomy.

INTRODUCTION: Triple pelvic osteotomy is known as a surgical option in young patients suffering from severe hip dysplasia. In most patients, implant removal is performed after bony consolidation. Due to the pelvic anatomy, the conventional technique is often associated with soft-tissue damage and high X-ray exposure. Recent developments in the field of computer-assisted surgery may offer new alternatives. The aim of this case report was to investigate the feasibility of a fluoroscopy-supported navigation system for the implant removal after a triple pelvic osteotomy. MATERIALS AND METHODS: Using the BrainLAB-VectorVision, a fluoroscopy-enhanced navigation system, implants were removed in a 24-year-old female patient 14 months after a triple pelvic osteotomy. RESULTS: The navigation system showed a high feasibility in the instrument visualisation and implant localisation. The screws could be precisely located, simultaneously in different X-ray planes. The total X-ray exposure time was low, totalling 17 s. CONCLUSION: Initial experiences are very promising and show impressively the advantages of fluoroscopy-supported navigation for minimally invasive implant removal. A considerably reduced X-ray exposure for patient and surgeon is possible. The removal of the inserted screw is possible through a stitch incision, with reduced OR trauma and a quicker reconvalescence.

Bacteria ingestion by blowfly larvae: an in vitro study.

BACKGROUND: Maggot debridement therapy is the medical use of live fly larvae for cleaning chronic and infected wounds, removing devitalized tissue and decreasing the risk of infection. Maggot-derived proteins are able to kill bacteria, and proteolytic enzymes are responsible for the liquefying of necrotic tissue. OBJECTIVE: The aim of this study is to investigate bacterial ingestion by larvae roaming free on bacterial agar, compared to those larvae contained within vinyl bags. METHODS: Free-roaming sterile larvae of Lucilla sericata and larvae contained in vinyl bags were fed on Escherichia coli producing green fluorescent protein (GFP). The time interval to the onset of fluorescent maggots was determined. At different time intervals, maggots were sacrificed, washed in sterile saline, sagittally cut in frozen sections and examined under a microscope with UV light. RESULTS: After feeding on GFP-labelled E. coli, maggots roaming free on bacterial lawn agar demonstrated fluorescence after 3 min, maggots entrapped in vinyl bags after 25 min. In the sagittal frozen sections, the highest fluorescent intensity was detected in the larvae's rostral part of the alimentary tract, the crop and the anterior midgut. CONCLUSION: In an in vitro setting, digestion and ingestion of whole or disintegrated bacteria is accomplished within minutes. The vinyl bag's permeable membrane clearly causes a delay of this process.

Sonographic evaluation of the elbow in rheumatoid arthritis: a classification of joint destruction.

The purpose of this study was to evaluate and classify sonographically the joint damage of the elbow in patients with rheumatoid arthritis. Standardized sonography of the elbow joint was performed in patients with rheumatoid arthritis between 1998 and 2002; from 2000 onwards in a controlled and prospective study. A grading of the joint damage was developed, evaluated and compared with the radiographic standard reference films of the Larsen classification. A total of 320 consecutive patients were included in this study; 250 elbows of 125 patients (93 women/32 men) were examined in a prospective way. Mean age was 62.5 years and mean disease duration was 11.9 years. The sonographically visible changes could be divided into six stages. In 24% of the patients graded Larsen 0, sonography detected definite abnormalities classified as stages 1 to 3. Sonography is a valuable tool to assess and classify elbow joint alteration in rheumatoid arthritis. Particularly in early stages of joint affection, ultrasound (US) is superior to X-ray in detecting soft tissue changes and minor erosions.

Ultrasound-guided decompression of the spinal canal in traumatic stenosis.

The purpose of this study was to examine the efficacy of ultrasound (US)-guided decompression of the myelon in the surgical treatment of spinal fractures. Intraoperative ultrasonography was performed in 22 patients with traumatic stenosis of the spinal canal during spinal cord surgery with removal of retropulsed bony fragments. US imaging requires a posterior approach and an enlarged foramen interarcuale. The posterior vertebral facet and the myelon can accurately be distinguished from small bony fragments by ultrasonography. Pre- and postoperative computed tomography was compared with intraoperative US imaging. Complete decompression of the spinal canal was controlled by US imaging of the restored ventral epidural space, as seen after repositioning of displaced fragments. Thus, the required extent of the surgical procedure was determined by intraoperative ultrasonography. We conclude that intraoperative US imaging is an important tool to monitor the restoration of the spinal canal and decompression of the spinal cord in case of fracture. The repositioning of stenosing bony fragments using surgical instruments can be monitored. US imaging as a real-time method intraoperatively provides the surgeon with additional information and significantly influences treatment options.