Use of a fluorescence imaging device to detect elevated bacterial loads, enhance antimicrobial stewardship, and increase communication across inpatient complex wound care teams.

INTRODUCTION: Wounds are increasing in number and complexity within the hospital inpatient system, and coordinated and dedicated wound care along with the use of emerging technologies can result in improved patient outcomes. OBJECTIVE: This prospective implementation study at 2 hospital inpatient sites examines the effect of bedside fluorescence imaging of wounds in the detection of elevated bacterial loads and its location in/around the wound on the inpatient wound population. MATERIALS AND METHODS: Clinical assessment and fluorescence imaging assessments were performed on 26 wounds in 21 patients. Treatment plans were recorded after the clinical assessment and again after fluorescence imaging, and any alterations made to the treatment plans after imaging were noted. RESULTS: Prior to fluorescence imaging, antimicrobial use in this patient population was common. An antimicrobial dressing, a topical antibiotic, or an oral antibiotic was prescribed in 23 wounds (88% of assessments), with antimicrobial dressings prescribed 73% of the time. Based on clinical assessment, more than half of the treated wounds were deemed negative for suspected infection. In 12 of 26 wounds, the fluorescence imaging information on bacterial presence had the potential to prompt a change in whether an antimicrobial dressing was prescribed. Five of these 12 wounds were fluorescence imaging-positive and an antimicrobial drug was not prescribed, whereas 7 of the 12 wounds were negative upon fluorescence imaging and clinical assessment but antimicrobial dressing was prescribed. Overall, fluorescence imaging detected 70% more wounds, with bacterial fluorescence indicating elevated bacterial loads, compared with clinical assessment alone, and use of imaging resulted in altered treatment plans in 35% of cases. CONCLUSIONS: Fluorescence imaging can aid in antimicrobial stewardship goals by supporting evidence-based decision-making at the point of care. In addition, use of such imaging resulted in increased communication, enhanced efficiency, and improved continuity of care between wound care providers and hospital sites.

An Ag2S@ZIF-Van nanosystem for NIR-II imaging of bacterial-induced inflammation and treatment of wound bacterial infection.

Bacterial diseases pose a serious threat to human health. Continued development of precise diagnostic methods and synergistic therapy techniques for combating bacteria are needed. Herein a hybrid nanosystem (Ag2S@ZIF-Van NS) was constructed by one-step self-assembly of Zn2+, vancomycin (Van) and Ag2S quantum dots (QDs). The nanosystem possesses excellent second near-infrared transparency window (NIR-II) fluorescence properties (∼1200 nm emission wavelength), good photothermal conversion properties, and biocompatibility. The material system enables precise, targeted NIR-II fluorescent imaging of bacterial inflammation in vivo as well as promoting anti-bacterial and wound healing effects.

Diagnosis and treatment of the invasive extension of bacteria (cellulitis) from chronic wounds utilising point-of-care fluorescence imaging.

Early diagnosis of wound-related cellulitis is challenging as many classical signs and symptoms of infection (erythema, pain, tenderness, or fever) may be absent. In addition, other conditions (ie, chronic stasis dermatitis) may present with similar clinical findings. Point-of-care fluorescence imaging detects elevated bacterial burden in and around wounds with high sensitivity. This prospective observational study examined the impact of incorporating fluorescence imaging into standard care for diagnosis and management of wound-related cellulitis. Two hundred thirty-six patients visiting an outpatient wound care centre between January 2020 and April 2021 were included in this study. Patients underwent routine fluorescence scans for bacteria (range: 1-48 scans/patient). Wound-related cellulitis was diagnosed in 6.4% (15/236) of patients. In these patients, fluorescence scans showed an irregular pattern of red (bacterial) fluorescence extending beyond the wound bed and periwound that could not be removed through cleansing or debridement, indicating the invasive extension of bacteria (wound-related cellulitis). Point-of-care identification facilitated rapid initiation of treatments (source control and antibiotics, when warranted) that resolved the fluorescence. No patients had worsening of cellulitis requiring intravenous antibiotics and/or hospitalisation. These findings demonstrate the utility of point-of-care fluorescence imaging for efficient detection and proactive, targeted management of wound-related cellulitis.

Use of fluorescence imaging to optimize location of tissue sampling in hard-to-heal wounds.

Introduction: Wound microflora in hard-to-heal wounds is invariably complex and diverse. Determining the interfering organisms(s) is therefore challenging. Tissue sampling, particularly in large wounds, is subjective and, when performed, might involve swabbing or biopsy of several locations. Fluorescence (FL) imaging of bacterial loads is a rapid, non-invasive method to objectively locate microbial hotspots (loads >104 CFU/gr). When sampling is deemed clinically necessary, imaging may indicate an optimal site for tissue biopsy. This study aimed to investigate the microbiology of wound tissue incisional biopsies taken from sites identified by FL imaging compared with sites selected by clinical judgment. Methods: A post hoc analysis of the 350-patient FLAAG wound trial was conducted; 78 wounds were included in the present study. All 78 wounds were biopsied at two sites: one at the center of the wound per standard of care (SoC) and one site guided by FL-imaging findings, allowing for comparison of total bacterial load (TBL) and species present. Results: The comparison between the two biopsy sites revealed that clinical uncertainty was higher as wound surface area increased. The sensitivity of a FL-informed biopsy was 98.7% for accurately finding any bacterial loads >104 CFU/g, compared to 87.2% for SoC (p=0.0059; McNemar test). Regarding species detected, FL-informed biopsies detected an average of 3 bacterial species per biopsy versus 2.2 species with SoC (p < 0.001; t-test). Microbial hotspots with a higher number of pathogens also included the CDC's pathogens of interest. Conclusions & perspective: FL imaging provides a more accurate and relevant microbiological profile that guides optimal wound sampling compared to clinical judgment. This is particularly interesting in large, complex wounds, as evidenced in the wounds studied in this post hoc analysis. In addition, fluorescence imaging enables earlier bacterial detection and intervention, guiding early and appropriate wound hygiene and potentially reducing the need for antibiotic use. When indicated, this diagnostic partnership with antibiotic stewardship initiatives is key to ameliorating the continuing threat of antibiotic resistance.

Comparative diagnostic accuracy of respective nuclear imaging for suspected fracture-related infection: a systematic review and Bayesian network meta-analysis.

BACKGROUND: The aim of this study was to compare the accuracy of available nuclear imaging modalities in the diagnosis of suspected fracture-related infection (FRI). METHODS: We conducted a comprehensive literature search of PubMed, EMBASE and the Cochrane Library to retrieve diagnostic accuracy studies in which FRI was investigated using different nuclear imaging modalities. The pooled sensitivity, specificity, likelihood ratios and diagnostic odds ratios were constructed using the bivariate meta-analysis framework, while the superior index was pooled using Bayesian network meta-analysis. RESULTS: 22 eligible studies (1,565 patients) were included in the quantitative analysis. A broad overlapping confidence interval (CI) of pooled sensitivity was observed among bone scintigraphy (0.94; 95% CI 0.85-0.98), 18F-FDG PET and PET/CT (0.91; 95% CI 0.85-0.94) and leukocyte scintigraphy (0.86; 95% CI 0.53-0.97). Bone scintigraphy (0.34; 95% CI 0.08-0.75) seemed to be less specific than all the other modalities, while leukocyte scintigraphy (0.96, 95% CI 0.92-0.98) was notably more specific than 18F-FDG PET and PET/CT (0.78; 95% CI 0.69-0.85). Based on the superiority index, 18F-FDG PET/CT (3.78; 95% CI 0.14-11.00), 18F-FDG PET (2.98; 95% CI 0.14-9.00) and leukocyte scintigraphy (1.51; 95% CI 0.11-7.00) all achieved high accuracy in detecting FRI. CONCLUSION: Bone scintigraphy is a highly sensitive nuclear imaging technique but lacks the specificity needed to unequivocally differentiate among various conditions suspected to be FRI. Leukocyte scintigraphy, 18F-FDG PET/CT and PET all present good satisfactory accuracy for the diagnosis of FRI, but their costs should be further reduced to promote their wide application.

The AMANDUS Project PART II-Advanced Microperfusion Assessed Non-Union Diagnostics with Contrast-Enhanced Ultrasound (CEUS): A Reliable Diagnostic Tool for the Management and Pre-operative Detection of Infected Upper-Limb Non-unions.

The management of upper-limb non-unions can be challenging, especially when infection is existent. Thus, pre-operative detection of infection plays a relevant role in non-union treatment. This study investigated in a large cohort the diagnostic potential of contrast-enhanced ultrasound (CEUS) as stand-alone method for differentiating between aseptic and infected upper-limb non-unions. Osseous perfusion of 50 upper-extremity non-unions (radius/ulna, n = 20; humerus, n = 22; clavicle, n = 8) was prospectively assessed with CEUS before revision surgery. The perfusion was quantified via time-intensity curves and peak enhancement (in arbitrary units). Significant perfusion differences between aseptic and infected non-unions could be detected (peak enhancement, p < 0.001). The sensitivity and specificity for the detection of infected upper-limb non-unions were 80% and 94.3% (cutoff peak enhancement: 130.8 arbitrary units). CEUS reliably differentiates between aseptic and infected upper-limb non-unions. Consequently, CEUS should be integrated into the daily diagnostic routine algorithm to plan non-union revision surgery more precisely as a single- or multi-step procedure.

Diagnostic Accuracy of Point-of-Care Fluorescence Imaging for the Detection of Bacterial Burden in Wounds: Results from the 350-Patient Fluorescence Imaging Assessment and Guidance Trial.

Objective: High bacterial load contributes to chronicity of wounds and is diagnosed based on assessment of clinical signs and symptoms (CSS) of infection, but these characteristics are poor predictors of bacterial burden. Point-of-care fluorescence imaging (FL) MolecuLight i:X can improve identification of wounds with high bacterial burden (>104 colony-forming unit [CFU]/g). FL detects bacteria, whether planktonic or in biofilm, but does not distinguish between the two. In this study, diagnostic accuracy of FL was compared to CSS during routine wound assessment. Postassessment, clinicians were surveyed to assess impact of FL on treatment plan. Approach: A prospective multicenter controlled study was conducted by 20 study clinicians from 14 outpatient advanced wound care centers across the United States. Wounds underwent assessment for CSS followed by FL. Biopsies were collected to confirm total bacterial load. Three hundred fifty patients completed the study (138 diabetic foot ulcers, 106 venous leg ulcers, 60 surgical sites, 22 pressure ulcers, and 24 others). Results: Around 287/350 wounds (82%) had bacterial loads >104 CFU/g, and CSS missed detection of 85% of these wounds. FL significantly increased detection of bacteria (>104 CFU/g) by fourfold, and this was consistent across wound types (p < 0.001). Specificity of CSS+FL remained comparably high to CSS (p = 1.0). FL information modified treatment plans (69% of wounds), influenced wound bed preparation (85%), and improved overall patient care (90%) as reported by study clinicians. Innovation: This novel noncontact, handheld FL device provides immediate, objective information on presence, location, and load of bacteria at point of care. Conclusion: Use of FL facilitates adherence to clinical guidelines recommending prompt detection and removal of bacterial burden to reduce wound infection and facilitate healing.

Use of a bacterial fluorescence imaging system to target wound debridement and accelerate healing: a pilot study.

OBJECTIVE: Optimal wound-bed preparation consists of regular debridement to remove devitalised tissues, reduce bacterial load, and to establish an environment that promotes healing. However, lack of diagnostic information at point-of-care limits effectiveness of debridement. METHOD: This observational case series investigated use of point-of-care fluorescence imaging to detect bacteria (loads >104CFU/g) and guide wound bed preparation. Lower extremity hard-to-heal wounds were imaged over a 12-week period for bacterial fluorescence and wound area. RESULTS: A total of 11 wounds were included in the study. Bacterial fluorescence was present in 10 wounds and persisted, on average, for 3.7 weeks over the course of the study. The presence of red or cyan fluorescent signatures from bacteria correlated with an average increase in wound area of 6.5% per week, indicating stalled or delayed wound healing. Fluorescence imaging information assisted in determining the location and extent of wound debridement, and the selection of dressings and/or antimicrobials. Elimination of bacterial fluorescence signature with targeted debridement and other treatments correlated with an average reduction in wound area of 27.7% per week (p<0.05), indicative of a healing trajectory. CONCLUSION: These results demonstrate that use of fluorescence imaging as part of routine wound care enhances assessment and treatment selection, thus facilitating improved wound healing.

The use of MolecuLight i:X device in acute hand trauma.

Early diagnosis of wound infections are crucial as they have been shown to increase patient morbidity and mortality. We evaluated the use of Moleculight i:X to identify infections in acute open wounds in hand trauma. Data were collected from patients who attended the hand trauma unit over a 4 week period prior to having surgery. Wounds were inspected for clinical signs of infection and autofluorescence images were taken using the Moleculight i:X device. Wound swabs were taken and results interpreted according to report by microbiologist. Autofluorescence images were interpreted by a clinician blinded to the microbiology results. 31 patients were included and data collected from 35 wounds. 3 wounds (8.6%) showed positive clinical signs of infection, 3 (8.6%) were positive on autofluorescence imaging and 2 (5.7%) of wound swab samples were positive for significant infection. Autofluorescence imaging correlated with clinical signs and wound swab results for 34 wounds (97.1%). In one case, the clinical assessment and autofluorescence imaging showed positive signs of infection but the wound swabs were negative. Autofluorescence imaging in acute open wounds may be useful to provide real-time confirmation of bacterial infection and therefore guide management.

A Prospective Multisite Observational Study Incorporating Bacterial Fluorescence Information Into the UPPER/LOWER Wound Infection Checklists.

INTRODUCTION: The UPPER/LOWER infection checklists look for signs and symptoms of local/superficial infection (UPPER) and deep infection (LOWER) to assist clinicians in identifying and distinguishing between these infection levels, facilitating appropriate treatment. The presence of 3 or more UPPER or LOWER criteria is indicative of infection. OBJECTIVE: This study evaluated the utility of incorporating real-time bacterial fluorescence imaging into the UPPER/LOWER checklists to enhance identification of infection in wounds. MATERIALS AND METHODS: This prospective, multisite study assessed 43 chronic wounds. Infection was identified in 27 wounds (62.8%) according to the UPPER/LOWER checklist criteria; 3 wounds were positive for both UPPER and LOWER infection, 1 wound was positive for LOWER infection only, and 23 wounds were positive for UPPER infection only. Fluorescence images were taken to detect wounds with high bacterial loads (> 104 CFU/g), indicated by the presence of red or cyan fluorescence. RESULTS: Red or cyan fluorescence from bacteria was observed in 88% of wounds (n = 38); all wounds positive for UPPER/LOWER were also positive for bacterial fluorescence. In 18 (41.9%) of the 43 wounds, fluorescence information added a third check to the UPPER/LOWER threshold, turning a negative diagnosis into a positive diagnosis of infection. Bacterial load was detected in 22/27 wounds swabbed, 17 of which exhibited heavy growth; in all wounds with detectable bacterial load, fluorescence signal was observed (positive predictive value = 100%, negative predictive value = 83%). Using microbiology as ground truth, inclusion of fluorescence information as an additional item in the checklists increased the sensitivity of the UPPER/LOWER checklist from 82% to 95%. CONCLUSIONS: These results suggest that the UPPER/LOWER checklist and fluorescence imaging work in a complementary manner to effectively identify wounds with high bacterial burden at the point-of-care.

Utility of MolecuLight i:X for Managing Bacterial Burden in Pediatric Burns.

Pediatric burn injuries are vulnerable to severe complications, most often infection, making prompt and precise diagnosis of bacterial bioburden vital to preventing detrimental consequences and optimizing patients' outcomes. Currently, burn wounds are assessed for infection via examining the clinical signs and symptoms of infection, which can be confirmed by swab culture analysis. While the former approach is subjective and experience-dependant, the latter technique is susceptible to missing subsurface, biofilm-associated colonization, and any peripheral bacterial burden, and also delays confirmation by up to 5 days. The MolecuLight i:X is a handheld, noncontact fluorescence imaging device, which can reveal real-time information about clinically significant levels of bacteria and their biodistribution in surface and subsurface burn wound tissues. We conducted a single-center observational study to assess the device efficacy in identifying critical bacterial levels in pediatric burn wounds and to test the children's compliance and the overall feasibility of the device integration into the current diagnostic practice. Ten patients with 16 wounds were recruited and assessed for the presence or absence of clinical signs and symptoms of infection and the presence or absence of bacterial fluorescence on images, with swabs taken to confirm findings. Results demonstrate the device's ability to visualize clinically significant bacterial burden and to localize distribution of pathogens. All clinicians agreed on the high compliance with the device and high feasibility of incorporating the device into routine wound assessments. The results of this study may pave the way toward including bacterial fluorescence imaging into the standard diagnostic algorithm for pediatric burn population.

Development of a Staphylococcus aureus reporter strain with click beetle red luciferase for enhanced in vivo imaging of experimental bacteremia and mixed infections.

In vivo bioluminescence imaging has been used to monitor Staphylococcus aureus infections in preclinical models by employing bacterial reporter strains possessing a modified lux operon from Photorhabdus luminescens. However, the relatively short emission wavelength of lux (peak 490 nm) has limited tissue penetration. To overcome this limitation, the gene for the click beetle (Pyrophorus plagiophtalamus) red luciferase (luc) (with a longer >600 emission wavelength), was introduced singly and in combination with the lux operon into a methicillin-resistant S. aureus strain. After administration of the substrate D-luciferin, the luc bioluminescent signal was substantially greater than the lux signal in vitro. The luc signal had enhanced tissue penetration and improved anatomical co-registration with infected internal organs compared with the lux signal in a mouse model of S. aureus bacteremia with a sensitivity of approximately 3 × 104 CFU from the kidneys. Finally, in an in vivo mixed bacterial wound infection mouse model, S. aureus luc signals could be spectrally unmixed from Pseudomonas aeruginosa lux signals to noninvasively monitor the bacterial burden of both strains. Therefore, the S. aureus luc reporter may provide a technological advance for monitoring invasive organ dissemination during S. aureus bacteremia and for studying bacterial dynamics during mixed infections.

Prospective randomized comparison of quality of regenerate in distraction osteogenesis of ring versus monolateral fixator in patients with infected nonunion of the tibia using digital radiographs and CT.

AIMS: In this randomized study, we aimed to compare quality of regenerate in monolateral versus circular frame fixation in 30 patients with infected nonunion of tibia. PATIENTS AND METHODS: Both groups were comparable in demographic and injury characteristics. A phantom (aluminium step wedge of increasing thickness) was designed to compare the density of regenerate on radiographs. A CT scan was performed at three and six months postoperatively to assess regenerate density. A total of 30 patients (29 male, one female; mean age 32.54 years (18 to 60)) with an infected nonunion of a tibial fracture presenting to our tertiary institute between June 2011 and April 2016 were included in the study. RESULTS: The regenerate mineralization on radiographs was comparable in both groups at two, four, six, and ten months' follow-up but the rail fixator group had statistically significant higher grades of mineralization when compared with the circular frame group at eight and 12 months' follow-up. The regenerate mineralization was also higher in the rail fixator group than in the circular frame group on CT at three and six months, although this difference was not statistically significant. CONCLUSION: Overall, the regenerate mineralization was higher in the monolateral than the circular frame group. A monolateral fixator may be preferred in patients with infected nonunion of the tibia with bone defects up to 7 cm. Cite this article: Bone Joint J 2019;101-B:1416-1422.

Fluorescence imaging guided dressing change frequency during negative pressure wound therapy: a case series.

OBJECTIVE: Knowledge of wound bioburden can guide selection of therapies, for example, the use of negative pressure wound therapy (NPWT) devices with instillation in a heavily contaminated wound. Wound and periwound bacteria can be visualised in real-time using a novel, non-contact, handheld fluorescence imaging device that emits a safe violet light. This device was used to monitor bacterial burden in patients undergoing NPWT. METHODS: Diverse wounds undergoing NPWT were imaged for bacterial (red or cyan) fluorescence as part of routine wound assessments. RESULTS: We assessed 11 wounds undergoing NPWT. Bacterial fluorescence was detected under sealed, optically-transparent (routine) adhesive before dressing changes, on foam dressings, within the wound bed, and on periwound tissues. Bacterial visualisation in real-time helped to guide: (1) bioburden-based, personalised treatment regimens, (2) clinician selection of NPWT, with or without instillation of wound cleansers, and (3) the extent and location of wound cleaning during dressing changes. The ability to visualise bacteria before removal of dressings led to expedited dressing changes when heavy bioburden was detected and postponement of dressing changes for 24 hours when red fluorescence was not observed, avoiding unnecessary disturbance of the wound bed. CONCLUSION: Fluorescence imaging of bacteria prompted and helped guide the timing of dressing changes, the extent of wound cleaning, and selection of the appropriate and most cost-effective NPWT (standard versus instillation). These results highlight the capability of bacterial fluorescence imaging to provide invaluable real-time information on a wound's bioburden, contributing to clinician treatment decisions in cases where bacterial contamination could impede wound healing.

Real-time bacterial fluorescence imaging accurately identifies wounds with moderate-to-heavy bacterial burden.

OBJECTIVE: Clinical evaluation of signs and symptoms (CSS) of infection is imperative to the diagnostic process. However, patients with heavily colonised and infected wounds are often asymptomatic, leading to poor diagnostic accuracy. Point-of-care fluorescence imaging rapidly provides information on the presence and location of bacteria. This clinical trial (#NCT03540004) aimed to evaluate diagnostic accuracy when bacterial fluorescence imaging was used in combination with CSS for identifying wounds with moderate-to-heavy bacterial loads. METHODS: Wounds were assessed by study clinicians using NERDS and STONEES CSS criteria to determine the presence or absence of moderate-to-heavy bacterial loads, after which the clinician prescribed and reported a detailed treatment plan. Only then were fluorescence images of the wound acquired, bacterial fluorescence determined to be present or absent and treatment plan adjusted if necessary. RESULTS: We examined 17 VLUs/2 DFUs. Compared with CSS alone, use of bacterial fluorescence imaging in combination with CSS significantly improved sensitivity (22% versus 72%) and accuracy (26% versus 74%) for identifying wounds with moderate-to-heavy bacterial loads (≥104 CFU/g, p=0.002). Clinicians reported added value of fluorescence images in >90% of study wounds, including identification of wounds incorrectly diagnosed by CSS (47% of study wounds) and treatment plan modifications guided by fluorescence (73% of study wounds). Modifications included image-guided cleaning, treatment selection, debridement and antimicrobial stewardship. CONCLUSION: Findings from this pilot study suggest that when used in combination with CSS, bacterial fluorescence may: (1) improve the diagnostic accuracy of identifying patients with wounds containing moderate-to-heavy bacterial loads and (2) guide more timely and appropriate treatment decisions at the point-of-care.

[18F]FDG PET/CT in non-union: improving the diagnostic performances by using both PET and CT criteria.

PURPOSE: Complete fracture healing is crucial for positive patient outcome. A major complication in fracture treatment is non-union. Infection is among the main causes of non-union and hence of osteosynthesis failure. For the treatment of non-union, it is crucial to understand whether a fracture is not healing because of an underlying septic process, since the surgical approach to non-unions definitely differs according to whether the fracture is infected or aseptic. We aimed to assess the diagnostic performance of 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography-computed tomography ([18F]FDG PET/CT) in the evaluation of infection as possible cause of non-union. METHODS: We retrospectively evaluated images of 47 patients treated in our trauma center who, between January 2011 and June 2017, underwent preoperative [18F]FDG PET/CT aiming to exclude infection in non-union. Clinical data, diagnostic examinations, laboratory and microbiology results, and patient outcome were collected and analyzed. [18F]FDG PET/CT images were visually and semiquantitatively evaluated using the maximum standardized uptake value (SUVmax). Imaging findings, as assessed by an experienced nuclear medicine physician and an experienced musculoskeletal radiologist, were compared with intraoperative microbiological culture results, which were used for final diagnosis (reference standard). The diagnostic performance of [18F]FDG PET/CT in detecting infected non-union was assessed. RESULTS: Twenty-two patients were not infected, while the remaining 25 had positive intraoperative microbiological results. C-reactive protein (CRP) was within the normal range in 13 cases (five with a final diagnosis of infection) and higher than normal in 25 patients (13 with a final diagnosis of infection). Infection was correctly detected on visual analysis of PET/CT images in 23 cases, while 2/25 infected patients had no significant [18F]FDG uptake and were considered false negatives. In seven cases, [18F]FDG PET/CT showed false positive results; 15/22 disease-free patients were correctly diagnosed. The diagnostic accuracy of [18F]FDG PET/CT in the final diagnosis of infection was 81% (38/47); its sensitivity, specificity, positive predictive value, and negative predictive value were 92%, 68%, 77%, and 88% respectively. The likelihood ratio for a positive test (LR+) was 2.89 and for a negative test, 0.12. Pretest probability of disease was 53%. Post-test probability based on LR+ was 77%. CONCLUSION: [18F]FDG PET/CT is a promising tool for diagnoses of infected non-unions. Both PET and CT images should be interpreted to achieve a high sensitivity (92%) and a very good negative post-test probability (12%).

Bioluminescent murine models of bacterial sepsis and scald wound infections for antimicrobial efficacy testing.

There are very few articles in the literature describing continuous models of bacterial infections that mimic disease pathogenesis in humans and animals without using separate cohorts of animals at each stage of disease. In this work, we developed bioluminescent mouse models of partial-thickness scald wound infection and sepsis that mimic disease pathogenesis in humans and animals using a recombinant luciferase-expressing Staphylococcus aureus strain (Xen29). Two days post-scald wound infection, mice were treated twice daily with a 2% topical mupirocin ointment for 7 days. For sepsis experiments, mice were treated intraperitoneally with 6 mg/kg daptomycin 2 h and 6 h post-infection and time to moribund monitored for 72 h. Consistent bacterial burden data were obtained from individual mice by regular photon intensity quantification on a Xenogen IVIS Lumina XRMS Series III biophotonic imaging system, with concomitant significant reduction in photon intensities in drug-treated mice. Post-mortem histopathological examination of wounds and bacterial counts in blood correlated closely with disease severity and total flux obtained from Xen29. The bioluminescent murine models provide a refinement to existing techniques of multiple bacterial enumeration during disease pathogenesis and promote animal usage reduction. The models also provide an efficient and information-rich platform for preclinical efficacy evaluation of new drug classes for treating acute and chronic human and animal bacterial infections.

Management of septic non-union of the tibia by the induced membrane technique. What factors could improve results?

INTRODUCTION: Management of septic non-union of the tibia requires debridement and excision of all infected bone and soft tissues. Various surgical techniques have been described to fill the bone defect. The "Induced Membrane" technique, described by A. C. Masquelet in 1986, is a two-step procedure using a PMMA cement spacer around which an induced membrane develops, to be used in the second step as a bone graft holder for the bone graft. The purpose of this study was to assess our clinical and radiological results with this technique in a series managed in our department. MATERIAL AND METHOD: Nineteen traumatic septic non-unions of the tibia were included in a retrospective single-center study between November 2007 and November 2014. All patients were followed up clinically and radiologically to assess bone union time. Multivariate analysis was used to identify factors influencing union. RESULTS: The series comprised 4 women and 14 men (19 legs); mean age was 53.9 years. Vascularized flap transfer was required in 26% of cases before the first stage of treatment. All patients underwent a two-step procedure, with a mean interval of 7.9 weeks. Mean bone defect after the first step was 52.4mm. The bone graft was harvested from the iliac crest in the majority of cases (18/19). The bone was stabilized with an external fixator, locking plate or plaster cast after the second step. Mean follow-up was 34 months. Bony union rate was 89% (17/19), at a mean 16 months after step 2. Eleven patients underwent one or more (mean 2.1) complementary procedures. Severity of index fracture skin opening was significantly correlated with union time (Gustilo III vs. Gustilo I or II, p=0.028). A trend was found for negative impact of smoking on union (p=0.06). Bone defect size did not correlate with union rate or time. DISCUSSION: The union rate was acceptable, at 89%, but with longer union time than reported in the literature. Many factors could explain this: lack of rigid fixation after step 2 (in case of plaster cast or external fixator), or failure to cease smoking. The results showed that the induced membrane technique is effective in treating tibial septic non-union, but could be improved by stable fixation after the second step and by cessation of smoking. LEVEL OF EVIDENCE: IV, Retrospective study.