Browsing by Author "Mader, Jon T."
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Item Acute septic arthritis(2002-10) Shirtliff, Mark E.; Mader, Jon T.Acute septic arthritis may develop as a result of hematogenous seeding, direct introduction, or extension from a contiguous focus of infection. The pathogenesis of acute septic arthritis is multifactorial and depends on the interaction of the host immune response and the adherence factors, toxins, and immunoavoidance strategies of the invading pathogen. Neisseria gonorrhoeae and Staphylococcus aureus are used in discussing the host-pathogen interaction in the pathogenesis of acute septic arthritis. While diagnosis rests on isolation of the bacterial species from synovial fluid samples, patient history, clinical presentation, laboratory findings, and imaging studies are also important. Acute nongonococcal septic arthritis is a medical emergency that can lead to significant morbidity and mortality. Therefore, prompt recognition, rapid and aggressive antimicrobial therapy, and surgical treatment are critical to ensuring a good prognosis. Even with prompt diagnosis and treatment, high mortality and morbidity rates still occur. In contrast, gonococcal arthritis is often successfully treated with antimicrobial therapy alone and demonstrates a very low rate of complications and an excellent prognosis for full return of normal joint function. In the case of prosthetic joint infections, the hardware must be eventually removed by a two-stage revision in order to cure the infection.Item Comparative evaluation of oral levofloxacin and parenteral nafcillin in the treatment of experimental methicillin-susceptible staphylococcus aureus osteomyelitis in rabbits(2001-08) Shirtliff, Mark E.; Calhoun, Jason H.; Mader, Jon T.Methicillim-susceptible Staphylococcus aureus (MSSA) is the most common pathogen recovered from osteomyelitis patients. The current standard therapeutic method for acute phase osteomyelitis is parenteral anitbiotic therapy. However, parental administration has negative aspects, such as secondary infection, patient inconvenience and high cost. The use of single oral antibiotic therapy may alleviate these problems. Therefore, the purpose of this study was to compare the effectiveness of standard once per day dosing of oral levofloxcin with a standard parenteral antibiotic regimen (nafcillin four times daily) for the treatment of experimental MSSA osteomyelitis in rabbits. Nearly all tibias from untreated infected controls (n = 27) revealed positive cultures (93%) for S. aureus, while the levofloxacin-treated group (n = 20) demonstrated significantly lower percentages of S. aureus infection (50%). The infected tibias of the nafcillin-treated group (n = 20) demonstrated significantly lower percentages (10%) of infected tibias than wither the controls or the levoflaxcin-treated groups (p < 0.05). The inferior efficacy of levoflaxcin may have been due to the pharmacokinetic profile of this fluorouinolone. The serum kinetics demonstrated that following single dose administration, levofloxacin was almost undetectable after 12 h. Studies in which levofloxacin is dosed every 12 h or given at increased doses in order to obtain bactericidal concentrations throughout the treatment regimen are needed.Item Experimental osteomyelitis treatment with antibiotic-impregnated hydroxyapatite(2002-08) Shirtliff, Mark E.; Calhoun, Jason H.; Mader, Jon T.A calcium hydroxyapatite antibiotic implant was evaluated to determine its efficacy as an antibiotic delivery system in a localized osteomyelitis rabbit model. Localized rabbit tibial osteomyelitis was developed with an intramedullary injection of methicillin resistant Staphylococcus aureus. Infected rabbits were randomized and divided into eight groups depending on treatment with or without debridement, systemic antibiotics, antibiotic-impregnated polymethylmethacrylate beads, or calcium hydroxyapatite implants with and without antibiotic impregnation. All treatments began 2 weeks after infection. After 4 weeks of therapy, the involved bones were cultured for concentrations of Staphylococcus aureus per gram of bone. Rabbits (n = 11) that had calcium hydroxyapatite (impregnated with vancomycin) implanted into the dead space after the debridement surgery had an 81.8% infection clearance after treatment. Rabbits (n = 10) that had polymethylmethacrylate beads (impregnated with vancomycin) implanted into the dead space after debridement surgery had a 70% clearance rate. All other treatment modalities resulted in less than 50% clearance rates. Calcium hydroxyapatite may be an effective alternative to polymethylmethacrylate for providing local antibiotic therapy in cases of methicillin resistant Staphylococcus aureus osteomyelitis.Item Gatifloxacin efficacy in treatment of experimental methicillin-sensitive staphylococcus aureus-induced osteomyelitis in rabbits(2002-01) Shirtliff, Mark E.; Calhoun, Jason H.; Mader, Jon T.The effectiveness of oral gatifloxacin was compared to that of standard parenteral antibiotic therapy (nafcillin) for the treatment of experimental methicillin-sensitive Staphylococcus aureus-induced osteomyelitis in a rabbit model. Gatifloxacin was as effective as nafcillin in clearing the infection. Therefore, oral gatifloxacin treatment of osteomyelitis may be an effective alternative to intravenous nafcillin treatment.Item Imaging in osteomyelitis and septic arthritis(2003) Shirtliff, Mark E.; Mader, Jon T.The diagnosis of osteomyelitis and septic arthritis depends on clinical presentation, appropriate cultures, laboratory tests, and imaging studies. During the initial evaluation of a patient suspected of having these musculoskeletal infections, radiography, ultrasound, magnetic resonance imaging (MRI) or computed tomography (CT), and radionuclide scans selectively are ordered to assist in the diagnosis, assess the extent of involvement, and guide the site selection for the bone biopsy. Conventional radiography should be performed on all patients. Radiographic changes in early osteomyelitis often are difficult to interpret and lag at least 2 weeks behind the evolution of infection. In patients with septic arthritis, radiographic images often are not revealing in the first few days of infection. However, initial radiographic images may be used to determine associated conditions such as osteoarthritis or simultaneous osteomyelitis, or to exclude neoplasm or injury. Therefore, after the infectious or inflammatory process has been detected and localized with this technique, further examinations by CT, MRI, biopsy, and cultures may be necessary to delineate the extent and etiology of the process. The use of ultrasound in the diagnosis of osteomyelitis is limited to the detection of soft tissue abnormalities around the bone. Ultrasound is a very powerful tool to detect early fluid effusions and to guide initial joint aspiration and drainage procedures. Ultrasound is the method of choice for treatment of patients with acute septic arthritis. CT provides images that display high spatial resolution and explicit cortical bony detail in patients with osteomyelitis. However, CT scans have limited use during the early stages of septic arthritis. MRI is superior to CT in localizing marrow extension and soft tissue changes. In patients with vertebral osteomyelitis, MRI should be used. MRI has the highest accuracy of all imaging techniques. The spatial resolution of MRI makes it more useful than CT or scintigraphy in the diagnosis of septic arthritis. Imaging with radiopharmaceuticals provides information regarding the pathophysiologic and pathobiochemical processes of inflammation, whereas radiography provides high-resolution morphologic information about the pathologic process. Technetium-99m methylene diphosphonate (99mTc MDP) usually is positive in biopsy-confirmed cases of hematogenous osteomyelitis. However, conditions that result in bone injury and repair cause constant bone turnover and focal uptake of 99mTc in bone. Using a three-phase 99mTc MDP followed by gallium-67 imaging increases specificity. Indium-111-labeled white blood cell (In-111 WBC) scintigraphy is very sensitive (except in some cases of chronic osteomyelitis), specific, and the method of choice for diagnosing and localizing distal appendicular skeletal osteomyelitis.Item Molecular interactions in biofilms(2002-08) Shirtliff, Mark E.; Mader, Jon T.; Camper, Anne K.A biofilm may be defined as a microbially derived, sessile community characterized by cells that are attached to an interface, embedded in a matrix of exopolysaccharide, and demonstrate an altered phenotype. This review covers the current understanding of the nature of biofilms and the impact that molecular interactions may have on biofilm development and phenotype using the motile gram-negative rod Pseudomonas aeruginosa and the nonmotile gram-positive cocci Staphylococcus aureus as examples.Item Osteomyelitis(2002) Mader, Jon T.; Wang, J.; Shirtliff, Mark E.; Calhoun, Jason H.