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A methodology used to isolate Escherichia coli O157:H7 from water and survival of this pathogen in inoculated water is described. The methodology used in the isolation of E. coli O157:H7 included the use of selective plating on Sorbitol MacConkey agar (supplemented with potassium tellurite [2.5 mg/liter], cefixime [0.05 mg/liter], and cefsulodin [10 mg/liter], and modified hemorrhagic colitis agar (also supplemented with potassium tellurite [2.5 mg/liter]) and cefsulodin [10 mg/liter]). There were no significant differences (P < 0.05) between the recoveries of E. coli O157:H7 on these two selective media. Direct plating on these selective agars was used to determine the length of time that E. coli O157:H7 was able to grow, remain viable, and be resistant to the selective agents. E. coli O157:H7 survived in inoculated water for up to > 300 days, depending on the type of water. Observation by scanning electron microscopy indicated that E. coli O157:H7 cells attached to, and multiplied on, the container walls.

Seventeen patients had gentamicin-PMMA beads implanted for treatment of orthopedic infections. The authors found that beads implanted in patients for 3 to 36 weeks were capable of eluting high levels of antibiotic after retrieval. Beads that were implanted in patients for less than 10 weeks eluted significantly higher antibiotic levels than beads were implanted for more than 14 weeks. This study supports the local use of these beads in the treatment of musculoskeletal infections.

A model was developed to identify and compare the local wound factors that induce acute osteomyelitis in a prospective, controlled investigation. When compared with wounds containing either virulent bacteria or dead bone, statistical analysis disclosed a significant increase in the incidence of osteomyelitis when virulent bacteria and dead bone were combined. The incidence of osteomyelitis in wounds containing an inoculated, hematoma-filled dead space was significantly less when compared with wounds containing dead bone and virulent bacteria. The incidence of osteomyelitis is significantly less when a nonvirulent strain of bacteria is substituted for a virulent strain. Although rigid internal fixation increased the incidence of osteomyelitis to 100% and long-term antibiotic therapy decreased the incidence, these changes were not statistically significant. These data allow the authors to predict the relative risk of osteomyelitis when these wound factors are present. The prevention of osteomyelitis depends on the clinical identification and modification of these local wound factors.

The successful treatment of osteomyelitis with commercially prepared gentamicin-polymethylmethacrylate (PMMA) (Septopal) beads and surgical debridement has led to the use of this technique in the United States. However, commercially prepared gentamicin-PMMA beads are not currently available to orthopedic surgeons in the United States. Therefore, these surgeons commonly manufacture their own antibiotic-containing cement beads in the operating room at the time of surgery. There is little data that compare the antibiotic elution characteristics of such preparations to commercially prepared gentamicin-PMMA beads. This study compares the measured amount of antibiotic elution of either gentamicin or tobramycin from laboratory manufactured Zimmer, Simplex, or Palacos beads to commercially prepared gentamicin-PMMA (Septopal) beads. During a 30-day study period, commercially prepared gentamicin-PMMA beads eluted more total antibiotic and maintain higher concentrations than did antibiotic acrylic composites manufactured in the authors' laboratory.

Tricalcium phosphate (TCP) is a porous ceramic which has biological properties of being non-reactive and resorbable, and acts as a scaffolding for bone ingrowth, undergoing progressive degradation and replacement by bone. Tricalcium phosphate has been shown to be comparable to autogenous bone graft in small periodontal defects. However, orthopedic defects are much larger. This prompted us to review the bone ingrowth potential in large cancellous bone defects (up to 12 cm3) in adult pigs. To quantitate bone ingrowth potential, three skeletally mature pigs had metaphyseal defects created in the tibia and femur of each hind limb, for 12 total sites. Twelve-cc defects in the distal femur and eight cc defects in the proximal tibia were made. Bone curetted was saved to be used as autogenous graft in the control, while the other ipsilateral defect was packed with tricalcium phosphate. Four months following the initial defect, the opposite hind extremity was similarly operated. All animals were sacrificed at nine months. Specimens were imbedded in methyl-methacrylate, cut at 120 microns, and stained. The quantity of regenerated bone was measured by histomorphometric techniques. Qualitative assessment at four months revealed absence of inflammation and TCP surrounded by trabecular bone, which was uniformly viable. There was very little TCP left by nine months. Quantitative analysis revealed the tibias to have a higher percent net bone replacement with TCP as compared to the control (32 percent versus 13 percent). The femoral TCP-filled defects were comparable to autogenous bone (both measured 29 percent).(ABSTRACT TRUNCATED AT 250 WORDS)

The migration of hardware has been a problem in the Luque system of segmental spinal instrumentation. To prevent this migration, a device was designed to slip on the 3/16th inch or 1/4 inch Luque rod. This prevents movement between the wire-rod interface, stopping both distal and proximal rotation of the rod. This article reports 21 patients with neuromuscular scoliosis on whom this technique was used. There was no migration of hardware and only one wire breakage in an area separate from the locking collar. These results are a marked improvement from patients of previous reports who did not receive the new device. Laboratory testing on the locking collar determined the best location on the "L" rod to be in the middle third of the rod. Rod migration has essentially been eliminated with this technique.

The local biology of distraction osteogenesis using Ilizarov and Wagner external fixators was compared in unilateral tibial lengthenings in two groups of eight dogs. Serial roentgenograms with histological correlation revealed some basic similarities as well as distinct differences between the two groups. All dogs fully bridged the experimental gap by intramembranous ossification. Subtle histological changes in the alignment of collagen bundles and subsequent ossification reflected the mechanical configuration of each fixator. The multiplanar, full-pin Ilizarov system delivered concentric load to the site of osteogenesis, inducing perfectly parallel columns of new bone. The uniplanar, one-half pin Wagner system induced angulation of the collagen and subsequent bone columns on the basis of eccentric load to the osteogenic interface. Despite a significant difference in axial rigidity, the Ilizarov and Wagner external fixators induced osteogenesis of equal volume.

Ten patients undergoing hip reconstructive procedures were given a single prophylactic dose of cefonicid 15 mg/kg to evaluate intraoperative and perioperative drug disposition in the surgical setting. Timed postinfusion serum samples were collected over 24 hours and resulting concentration versus time data were subjected to noncompartmental pharmacokinetic analysis. Bone samples were obtained in eight of ten patients with mean bone concentrations of 13.3 micrograms/g (range 8.2-25.1). Postinfusion serum concentrations at five minutes postinfusion ranged from 200.8 to 316.7 micrograms/ml; the 12-hour mean was 19.1 micrograms/ml (range 4.0-48) and the 24-hour mean was 4.3 micrograms/ml (range 0.0-13.8). Protein binding at three sampling times ranged from 88 to 96.5 percent, increasing over time as total cefonicid concentrations fell. The mean half-life in our patients was 3.5 hours, compared with 4.8 hours in our four controls. These data indicate that altered protein binding and intraoperative events alter the disposition of cefonicid. Although differences in disposition parameters between patients and controls were not statistically significant, suboptimal serum cefonicid concentrations were observed in four orthopedic patients.

Lymphopoiesis was studied by electron microscopy in the palatine tonsil of the rabbit from 18 days gestation to 5 days after birth. At 18 days tonsils formed as mounds of mesenchyma covered with epithelium. At 19 days the basal epithelial cells started to increase in number, eventually forming 'buds' which projected into the mesenchyme. Simultaneously, lymphocytes appeared nearthe epithelium or buds. There was marked resemblance between the basal epithelial cells and the lymphocytes. Budding slowed down after the 25th day, but individual basal cells continued to migrate into the mesenchyme and lymphocytes increased in number. Ultrastructure wassimilar in both types of cells, and differentfrom mesenchymal cells. At 29 days lymphocytes were found in the basal epithelial layer behind an intact basement membrane. The evidence indicated that lymphocytes were derived from epithelium.