Fresh-frozen allograft bone is frequently used in orthopaedic surgery. We investigated the incidence of allograft-related infection and analysed the outcomes of recipients of bacterial culture-positive allografts from our single-institute bone bank during bone transplantation. The fresh-frozen allografts were harvested in a strict sterile environment during total joint arthroplasty surgery and immediately stored in a freezer at -78º to -68º C after packing. Between January 2007 and December 2012, 2024 patients received 2083 allografts with a minimum of 12 months of follow-up. The overall allograft-associated infection rate was 1.2% (24/2024). Swab cultures of 2083 allografts taken before implantation revealed 21 (1.0%) positive findings. The 21 recipients were given various antibiotics at the individual orthopaedic surgeon’s discretion. At the latest follow-up, none of these 21 recipients displayed clinical signs of infection following treatment. Based on these findings, we conclude that an incidental positive culture finding for allografts does not correlate with subsequent surgical site infection. Additional prolonged post-operative antibiotic therapy may not be necessary for recipients of fresh-frozen bone allograft with positive culture findings.

Cite this article: Bone Joint J 2015;97-B:427–31.

Fresh-frozen allograft bone is frequently used in orthopaedic surgery. We investigated the incidence of allograft-related infection and analysed the outcomes of recipients of bacterial culture-positive allografts from our single-institute bone bank during bone transplantation.

The fresh-frozen allografts were harvested in a strict sterile environment during total joint arthroplasty surgery and immediately stored in a freezer at −78° to −68° C after packing. Between January 2007 and December 2012, 2024 patients received 2083 allografts with a minimum of 12 months of follow-up.

The overall allograft-associated infection rate was 1.2% (24/2024). Swab cultures of 2083 allografts taken before implantation revealed 21 (1.0%) positive findings. The 21 recipients were given various antibiotics at the individual orthopaedic surgeon's discretion. At the latest follow-up, none of these 21 recipients displayed clinical signs of infection following treatment.

Based on these findings, we conclude that an incidental positive culture finding for allografts does not correlate with subsequent surgical site infection. Additional prolonged post-operative antibiotic therapy may not be necessary for recipients of fresh-frozen bone allograft with positive culture findings.

Chang Gung Medical Foundation

Aim. At our tertiary orthopaedic centre, mycobacterial cultures are routinely performed on bone and joint samples sent for bacterial culture. We have previously described the prevalence Mycobacterium tuberculosis Complex (MTBC) in these samples. Here, we describe the prevalence of non-tuberculous mycobacteria (NTM). We calculate the number needed to test to identify one previously undiagnosed mycobacterial bone or joint infection. Methods. Samples taken during a single procedure were pooled in one BACTEC MGIT culture. From laboratory records, we ascertained the number of mycobacterial cultures performed, the number positive for MTBC or NTM, and characteristics of individuals from whom mycobacteria were isolated. We collected the same data from 100 individuals with negative mycobacterial cultures. Results presented here are from interim analysis. Results. Excluding sample types that were clearly not bone or joint samples, 6162 mycobacterial cultures were performed between 4 July 2017 and 30 September 2022. Twenty-two patients had MTBC and 6 patients had NTM newly isolated from bone or joint samples placed in mycobacterial culture, with a further patient having both M. tuberculosis and M. avium isolated. In both patients with M. abscessus, the organism also grew in routine bacterial cultures. In one further patient, M. fortuitum was isolated from a sample not put into mycobacterial culture. To identify one new mycobacterial infection of bone or joint (MTBC or NTM) that would not be detected with routine bacterial cultures, 228 (95% CI 157 – 346) mycobacterial cultures were needed. The laboratory cost per additional patient identified using MGIT cultures was €12,540 (95% CI €8,635 - €19,030). Mycobacterial cultures were much less likely to be positive in samples taken from prosthetic joints. They were more likely to be positive in spinal samples and in samples taken from patients with suspected sarcoma. In patients for whom we had contemporaneous histological specimens, these demonstrated granulomatous inflammation in 86% (18/21) of patients from whom MTBC had been isolated but in neither of the two patients from whom only NTM was isolated. Ascertaining the clinical significance of NTM isolates is challenging, although in 2/8 cases the same organism was isolated following repeat sampling. Conclusions. Targeted rather than routine mycobacterial culture of bone and joint specimens should be considered in settings with a low burden of tuberculosis. NTM are rarely isolated from bone and joint specimens at our centre and fast growers may be isolated using routine bacterial culture

Aim. The pathogenesis of non-union is multifactorial. Path biological factors, mechanical factors, and low-grade-infection contribute to impaired bone healing. Aim of this study was to determine the rate of low-grade-infection in patients with long bone non-union of the lower extremity without signs of acute infection, the influence of CRP (C-reactive protein), and the outcome. Method. In a retrospective study (2003–2013), all patients who underwent surgery for treatment of tibial- or femoral-shaft-non-union without any clinical evidence of infection were assessed. Bacterial cultures harvested during non-union revision, the CRP and WBC (white blood cells) values at hospital admission, the outcome, and epidemiological data were analysed. Results. In 88 patients with tibial-shaft-non-union without any clinical signs of infection, bacterial samples remained negative in 51 patients (46 yr; 33% open fracture; 33% nicotine abuse; 8% diabetes mellitus; revision of non-union 10.9 months following primary osteosynthesis). In 37 patients (46 yr; 54% open fracture; 42% nicotine abuse; 11% diabetes mellitus; revision of non-union 15.2 months) microbiological diagnostic studies after long-term-culturing demonstrated positive bacterial cultures whereas after short-term-culturing for 2 days only 17 positive cultures were observed. Among patients with negative bacterial cultures bone healing was achieved after 13.2 months, whereas in 29% additional surgical interventions (1.3 procedures) were necessary. Non-union with positive bacterial cultures required 22.9 months (p-value<0.01) until bone healing, and even 57% of these patients required additional operations (2.9 procedures; p-value<0,01). Hematological studies performed at hospital admission demonstrated no significant difference regarding CRP (negative vs. positive culture: 0.8 mg/dl vs. 1.9 mg/dl) and WBC (negative vs. positive culture: 7.6/nl vs. 7.8/nl). Comparable results were observed in 86 patients with femoral-shaft-non-union (38 patients with positive bacterial cultures after long-term-culturing and 18 patients after short-term-culturing) with an increased number of required operations (0.8 vs. 1.6 procedures; p-value<0.05) and a longer time period until bone healing (18.2 months vs. 27.2 months; p-value<0.05) in the group with positive bacterial cultures. In contrast to tibial-shaft-non-union, a significant difference of the CRP level was observed (negative vs. positive culture: 0.8 mg/dl vs. 2.7 mg/dl; p-value<0.01). Conclusions. The pathogenesis of non-union may originate from low-grade-infection even in patients without any signs of infection and may result in increased number of required surgical interventions. Therefore, during any non-union revision surgery, multiple bacterial samples should be harvested for long-term-culturing. Possibly, increased CRP levels may be a predictor for low-grade-infection in femoral – but not in tibial-shaft-non-union

Aim. Surgical treatment of ankle fractures comes with a substantial risk of complications, including infection. An unambiguously definition of fracture-related infections (FRI) has been missing. Recently, FRI has been defined by a consensus group with a diagnostic algorithm containing suggestive and confirmatory criteria. The aim of the current study was to report the prevalence of FRI in patients operated for ankle fractures and to assess the applicability of the diagnostic algorithm from the consensus group. Method. Records of all patients with surgically treated ankle fractures from 2015 to 2019 were retrospectively reviewed for signs of postoperative infections. Patients with suspected infection were stratified according to confirmatory or suggestive criteria of FRI. Rate of FRI among patients with confirmatory and suggestive criteria were calculated. Results. Suspected infection was found in 104 (10%) out of 1004 patients. Among those patients, confirmatory criteria were met in 76/104 (73%) patients and suggestive criteria were met in 28/104 (27%) at first evaluation. Patients with clinical confirmatory criteria (N= 76) were diagnosed with FRI. Patients with suggestive criteria were further examined with either bacterial sampling at the outpatient clinic, revision surgery including bacterial sampling, or a wait-and-see approach. Eleven (39%) of the 28 patients had positive cultures and were therefore diagnosed as having FRI at second evaluation. In total 87 (9%) patients were diagnosed with FRI according to the consensus definition. Only 73 (70%) of the 104 patients with suspected FRI had adequate bacterial sampling. Conclusions. The prevalence of FRI, applying the FRI-consensus criteria, for patients with surgically treated ankle fractures was 9%. Twenty-two percent of patients who met the confirmatory criteria had negative bacterial cultures. The current study shows that we did not have a systematic approach to patients with suspected FRI as recommended by the consensus group. A systematic approach to adequate bacterial sampling when FRI is suspected is paramount. The consensus definition of FRI and its diagnostic algorithm facilitates such an approach

Aim. Differentiation of infected (INF) nonunion from aseptic (AS) nonunion is crucial for the choice of intra- and postoperative treatment. Preoperative diagnosis of infected nonunion is challenging, especially in case of low-grade infection lacking clinical signs of infection. Standard blood markers such as C-reactive protein or leucocyte count do not aid in preoperative diagnosis. Proteomic profiling has shown promising results for differentiation of numerous chronic disease states, and in this study was applied to preoperative blood samples of patients with nonunion in an attempt to identify potential biomarkers. Method. This prospective multicenter study enrolled patients undergoing revision surgery of femur or tibia nonunion. Patients with implant removal after regular fracture healing (HEAL) were included as a control-group. Preoperative blood samples, intraoperative tissue samples, sonication of osteosynthesis material and 1-year-follow-up questionnaire were taken. Nonunion patients were grouped into INF or AS after assessing bacterial culture and histopathology of retrieved samples. Diagnosis of infection followed the fracture related infection consensus group criteria, with additional consideration of healing one year after revision surgery. Targeted proteomics was used to investigate a predefined panel of 45 cytokines in preoperative blood samples. Statistical differences were calculated with Kruskal Wallis and Dunn's post hoc test. Cytokines with less than 80% of samples being above the lower limit of detection range (LLDR) were excluded for this study. Results. We recruited 62 AS, 43 INF and 32 HEAL patients. Patients in the two nonunion groups (INF and AS) did not differ concerning smoking, diabetes or initial open or closed fracture. Thirty-two cytokines were above LLDR in >80% of patients. INF patients showed a significant difference in expression of 8 cytokines compared to AS, with greatest differences observed for Macrophage Colony Stimulating Factor 1 (MCSF-1) and Hepatocyte Growth Factor (HGF) (p<0.01). In comparing AS with HEAL patients, 9 cytokines displayed significant differences, including interleukin (IL)-6, Vascular Endothelial Growth Factor A (VEGFA), Matrix Metalloproteinase 1 (MMP-1). Comparison of INF with HEAL patients revealed significantly different expression of 20 cytokines, including. IL-6, IL-18, VEGFA or MMP-1. Conclusions. Our study revealed differences in plasma cytokine profile of blood samples from INF and AS patients. Although no single biomarker is sufficient to differentiate these patients preoperatively in isolation, future multivariant analysis of this cytokine data in combination with clinical characteristics may provide valuable diagnostic insights. Funded by German Social Accident Insurance (FF-FR 0276) and AO Trauma (AR2021_04)

Aim. In recent years, many studies on revision for infection after arthroplasty have been published. In national arthroplasty registers, revision for infection is defined as surgical debridement, with or without removal or exchange of the entire or parts of the prosthesis due to deep infection, and should be reported to the register immediately after surgery. The diagnosis of infection is made at the surgeon's discretion, based on pre- and perioperative assessment and evaluation, and is not to be corrected to the register based on peroperative bacterial cultures. Due to this lack of validation, the rate of revision for infection will only be an approximation of the true rate of periprosthetic joint infection (PJI). Our aim was to validate the reporting of infection after total hip arthroplasty, and to assess if revisions for infection actually represented true PJI. Methods. We investigated the reported revisions for infection and aseptic loosening after total hip arthroplasty from 12 hospitals, representing one region of the country, reported during the period 2010–2020. The electronic patient charts were investigated for information on surgical treatment, use of antibiotics, biochemistry and microbiology findings. PJI was defined as growth of at least two phenotypically identical microbes in perioperative tissue samples. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy were calculated. Results. 145 revisions for infection and 137 revisions for aseptic loosening were reported. Of the reported infections, there were 141/145 true positives and 4/145 false positives. Of the reported aseptic loosenings, there were 126/137 true negatives and 11/137 false negatives. This gives a positive predictive value of 0.97, negative predictive value of 0.92, sensitivity of 0.93, specificity of 0.97 and accuracy of 0.95. Interpretation. We found the reporting revision for infection after total hip arthroplasty to the national register accurate. There was high correlation between reported revision for infection and PJI. Studies on revision for infection from arthroplasty registers may therefore be considered as reliable as studies of true PJI

Aim. A novel anti-infective biopolymer implant coating was developed to prevent bacterial biofilm formation and allow on-demand burst release of anti-infective silver (Ag) into the surrounding of the implant at any time after surgery via focused high-energy extracorporeal shock waves (fhESW). Method. A semi-crystalline Poly-L-lactic acid (PLLA) was loaded with homogeneously dissolved silver (Ag) applied onto Ti6Al4V discs. A fibroblast WST-1 assay was performed to ensure adequate biocompatibility of the Ag concentration at 6%. The prevention of early biofilm formation was investigated in a biofilm model with Staphylococcus epidermidis RP62A after incubation for 24 hours via quantitative bacteriology. In addition, the effect of released Ag after fhESW (Storz DUOLITH SD1: 4000 impulses, 1,24 mJ/mm. 2. , 3Hz, 162J) was assessed via optical density of bacterial cultures (Escherichia coli TG1, Staphylococcus epidermidis RP62A, Staphylococcus aureus 6850) and compared to an established electroplated silver coating. The amount of released Ag after the application of different intensities of fhESW was measured and compared to a control group without fhESW via graphite furnace atomic absorption spectrometry (GF-AAS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Results. The coating with 6% Ag reduced Staphylococcus epidermidis biofilm formation by 99.7% (mean±SD: 2.1×10^5 ± 3,9×10^5 CFU/µL) compared to uncoated controls (6.8×10^7 ± 4.9×10^7 CFU/µL); (p=0.0001). After applying fhESW the commercially available electroplated silver coating did not prevent the growth of all tested bacterial strains. Bacterial growth is delayed with 4% Ag and completely inhibited with 6% Ag in the novel coating, except for a small increase of S. aureus after 17 hours. SEM and EDS confirmed a local disruption of the coating after fhESW. Conclusions. This novel anti-infective implant coating has the potential to prevent bacterial biofilm formation. The on-demand burst release of silver via fhESW could be an adjunctive in the treatment of implant related infection and is of particular interest in the concept of single stage revision surgery

Aim. Bone and Joint Infections (BJIs) present with non-specific symptoms and can be caused by a wide variety of bacteria and fungi, including many anaerobes and microorganisms that can be challenging to culture or identify by traditional microbiological methods. Clinicians currently rely primarily on culture to identify the pathogen(s) responsible for infection. The BioFire. ®. FilmArray. ®. Bone and Joint Infection (BJI) Panel (BioFire Diagnostics, Salt Lake City, UT) was designed to detect 15 gram-positive (seven anaerobes), 14 gram-negative bacteria (one anaerobe), two yeast, and eight antimicrobial resistance (AMR) genes from synovial fluid specimens in an hour. The objective of this study was to evaluate the performance of an Investigational Use Only (IUO) version of the BioFire BJI Panel (BBJIP) compared to conventional used as reference methods. Method. In a monocentric study, leftover synovial fluid specimens were collected in a single institution including 4 hospitals and tested using conventional bacterial culture (Standard of Care (SoC)) according to routine procedures following French national recommendations. Specimen has been placed in a refrigerator (4°C) as soon as possible after collection and stored for less than or equal to 7 days before enrollment. Performance of the IUO version of the BBJIP was determined by comparison to SoC for species identification. Results. To date, 201 specimens have been collected and tested using BBJIP. A total of 39 pathogens were obtained in culture. Compared to SoC culture, the overall PPA was 89.7% (35 TP, 4 FN (SA, 1; Strepto Spp, 2; P. micra, 1) and the overall NPA was 99.7% with 16 FP for a total of 5374 bacterial targets screened. Two complementary molecular tests using home-made PCR are underway to definitively conclude about the FN et FP for BBJIP observed in the preset study. Conclusions. The BioFire BJI Panel appears as a promising, sensitive, specific, and robust test for rapid detection of 31 microorganisms (including anaerobes) and eight AMR genes in synovial fluid specimens. The number of pathogens and resistance markers included in the BioFire BJI Panel, together with a reduced time-to-result and increased diagnostic yield compared to culture, is expected to aid in the management of BJIs

INTRODUCTION. Peri-prosthetic fungal infection is generally considered more difficult to cure than a bacterial infection. Two-stage exchange is considered the gold standard of surgical treatment. A recent study, however, reported a favorable outcome after one stage exchange in selected cases where the fungus was identified prior to surgery. The routine one stage exchange policy for bacterial peri-prosthetic infection involves the risk of identifying a fungal infection mimicking bacterial infection solely on intraoperative samples, i.e. after reimplantation, realizing actually a one stage exchange for fungal infection without pre-operative identification of the responsible fungus, which is considered to have a poor prognosis. We report two such cases of prosthetic hip and knee fungal infection. Despite this negative characteristic, no recurrence of the fungal infection was observed. CASE N°1: A 78 year old patient was referred for loosening of a chronically infected total hip arthroplasty (Staphylococcus aureus and Streptococcus dysgalactiae). One stage exchange was performed. Intraoperative bacterial cultures remained sterile. Two fungal cultures were positive for Candida albicans. Antifungal treatment was initiated for three months. No infection recurrence was observed at three year follow up. CASE N° 2: A 53-year-old patient was referred for loosening of a chronically infected total knee prosthesis (Staphylococcus aureus methicillin susceptible, Klebsiella pneumoniae and Staphylococcus epidermidis). One stage exchange was performed. Intraoperative bacterial cultures remained sterile. Five fungal cultures were positive for Candida albicans. Antifungal treatment was initiated for three months. No infection recurrence was observed at two-year follow-up. DISCUSSION. This experience suggests that eradication of fungal infection of a total hip or knee arthroplasty may be possible after one stage exchange even in cases where the diagnosis of fungal infection was not known before surgery, when the fungus was not identified and its antifungal susceptibility has not been evaluated before surgery. It is however not possible to propose this strategy as a routine procedure. CONCLUSION. We suggest evaluating the results of one stage exchange for peri-prosthetic fungal infection on a larger scale

We studied twelve parameters (physical appearance, mucin clot, fibrin clot, white cell count, differential count, red blood cell count, gram stain for bacteria, crystal microscopy, aerobic bacterial culture, anaerobic bacterial culture and ratio between synovial sugar and blood sugar) in over 300 samples of synovial fluid from patients with a variety of suspected pathologies (e.g. infection, inflammatory disease, infection adjacent to a joint, aseptic loosening of a prosthesis). The diagnosis of infection was further established using clinical signs, radiological features, full blood count, C-reactive protein and iron profile. Many of the patients came to surgery. This of course created further opportunity to establish or rule out the diagnosis of infection with greater certainty. Nine of the features of synovial fluid were analysed statistically, including turbidity, diminished viscosity, mucin clot, fibrin clot, total white cell count, polymorphs greater than 60%, bacteria observed on direct microscopy, bacteria yielded by culture and concentration of synovial sugar less than 40% of the simultaneous blood sugar. The positive or negative features of infection were determined to be true or false in the light of the cumulative overall features of infection. The data so obtained was analysed to establish sensitivity, specificity, positive predictive value, negative predictive value and accuracy. The mass of data so obtained cannot be meaningfully expressed in such a brief abstract. Important examples are when culturing synovial fluid there were 44% false negatives or no growth and 56% true positives. Looking at the ratio between synovial sugar and blood sugar we found that taking 40% as the critical value, this was 62% sensitive, the specificity was 89%, the accuracy was 73%, the positive predictive value was 89%, the negative predictive value was 62.4%. However we went further and separated those who were definitely infected or probably infected i.e. Groups 4 & 5 from those who were probably or definitely NOT infected according to the sum of clinical laboratory and radiological parameters. When thus separated the predictive value of a positive result was 100% in Group 4 & 5 and 0% in Group 1 & 2. The predictive value of a negative result in Group 1 & 2 was 98.7% accurate and 22.4% in Group 4 & 5

Aim. Posttraumatic pelvic-osteomyelitis is one of the most serious complications after pelvic-fractures. The necessary extensive surgical debridement as part of interdisciplinary treatment is complicated by the possible persistence of pelvic instability. The aim of this study was to determine the outcome and outline the course of treatment after early posttraumatic pelvic bone infections due to type-C pelvic ring injuries. Method. In a retrospective cohort study (2005–2015) all patients with pelvic-osteomyelitis within six weeks of surgical stabilization of a type-C pelvic-fracture were assessed. Microbiological results, risk factors, course of treatment and functional long-term outcome using the Orlando-Pelvic-Score were analyzed. Results. A total of 18 patients (age 43.7 years; Body-Mass-Index 27.9 kg/m2; ASA-physical-status 1.8; Injury-Severity-Score 38) developed a pelvic-osteomyelitis within an average of 27 days after internal surgical stabilization of a type-C pelvic injury (AO-type C1: 10, C2: 4, C3: 4). Os pubis was affected in 7 and Os ilium in 11 cases. In addition to the pelvic-fracture, major vascular injuries occurred in 8, nerve injuries in 9, and intestinal and/or bladder ruptures in 11 cases. In 14 cases a mass transfusion was necessary. In addition to clinical signs of inflammation, (10 × redness, 12 × wound secretion, 6 × fistula) elevated levels of c-reactive-protein (7.7 mg/dl) and white-blood-cells (10.5/nl) were found. Bacterial cultures harvested during the initial surgical revision demonstrated mixed cultures in 17/18 cases, with an average of 3 different organisms isolated per case (61% intestinal bacteria). During the scheduled repetitive debridement a reduction of the initial mixed cultures into a single organism was observed. Overall 6.8 surgical interventions, including implant removal, were necessary until osteomyelitis was eradicated. In no cases was re-osteosynthesis performed. In 6/18 cases recurrence of infection occurred after an average of 5 months, followed by an additional repetitive debridement. An average 3-year-follow-up after the initial osteomyelitis-diagnosis demonstrated eradication of infection in 17/18 cases combined with an Orlando-Pelvic-Score of 21.9 points (best possible function: 40 points). Despite significant pelvic malalignment the ability to walk was achieved in all patients, with one exception due to a spinal cord injury. Conclusions. Despite no new surgical stabilization of the initial unstable pelvic injury, the early removal of implants combined with extensive debridement and antibiotic therapy led to sufficient long-term outcomes in patients with early posttraumatic pelvic-osteomyelitis. In particular, due to the severity of the initial injury and the complex interdisciplinary approach, early diagnosis of the osteomyelitis is essential

Aim. S. aureus and coagulase-negative staphylococci are the most frequent bacteria responsible for PJI. In patients with acute PJI (i.e. <1 month following the implantation), DAIR with exchange of removal components followed by a combination of antibiotics that includes rifampin (particularly rifampin+fluoroquinolone) are recommended. Unfortunately, some patients could not receive rifampin due to drug-drug interaction or stopped it due to an adverse event. Finally, it was unclear if the dose and the duration of rifampin influenced the prognosis. Method. We performed a retrospective cohort study in 4 hospitals and included patients with staphylococcal acute post-operative (< 1 month) PJI treated with DAIR in 2011–2016 period. Univariate and multivariate Cox analysis and Kaplan Meier curves were used to determine the risk factors for treatment failure (persistence of clinical signs, new surgery w/o persistence or superinfection, infection-related death). Results. 79 patients were included (median age: 71 years IQR 53–89]; 55 men [69.6 %]; median ASA score: 2 [IQR 2–3]). Bacterial cultures revealed 65 S. aureus (82.3 %) and 15 coagulase-negative staphylococci (19.0 %) infections, including 14 methicillin-resistant isolates (17.7 %). Among all isolates, only 2 (2.5 %) were resistant to rifampin and 16 (20.3 %) were resistant to fluoroquinolone. The median duration of antimicrobial therapy was 92 days (IQR 31–152). Only 59 patients received rifampin (74.7 %), and 35 (44.3 %) the combination rifampin + fluoroquinolone. Median duration of rifampin was 56.5 days (IQR 15.8–86.0) and median dose 14.6mg/kg/d (IQR 13.0–16.7). Forty patients (50.6 %) received rifampin in the first 2 weeks and 43 patients (54.4 %) received at least 2 weeks of rifampin. Six patients (7.6 %) developed an adverse event leading to rifampin interruption. During a median follow-up of 443 days (IQR 219.5–790.5), 21 patients (26.6 %) experienced a treatment failure including 12 persistence of the initial pathogen (57.1 %) and 9 superinfections (42.9 %). An ASA score >2 (HR 2.8; 95%CI 1.26–6.15), the use of rifampin (HR 0.4; 95% CI 0.17–0.95) and the duration of rifampin treatment (HR 0.83; 95%CI 0.75–0.92 per additional week of treatment) were significant determinants of the outcome (but not methicillin-resistance). Receiving >2 weeks of rifampin prevented the failure, but an introduction during the first 2 weeks did not influence the outcome. Conclusions. In patients with staphylococcal acute PJI, the use of rifampin and its duration strongly influenced the prognosis. As 25% of patients could not receive rifampin, new drugs with anti-biofilm activity are required

Aim. We used a polymerase chain reaction (PCR) lateral flow assay1) to rapidly diagnose joint infection. We evaluated the usefulness of multiplex-PCR (PCR lateral flow assay: PCR-LF) using detailed clinical data. Method. A total of 35 synovial fluid samples were collected from 26 patients in whom bacterial infection was suspected, including 22 from knee joints, 11 from hip joints, and 2 from other joints. After purifying the DNA from the samples, multiplex PCR targeting two MRSA-associated genes (femA and mecA) and the bacterial 16S rRNA gene was performed. Amplified gene fragments were specifically detected with DNA probes immobilized on stick devices through DNA-DNA hybridization and visualization, enabling diagnosis of MRSA, MSSA, MRCNS, gram-positive, and/or gram-negative bacterial infection. Genetic identification of bacteria by determining the 16S rRNA gene sequence was also performed using multiplex PCR-positive samples. Finally, the usefulness of our PCR-LF method was evaluated using detailed clinical data. Results. The results of PCR-LF were 9 gram-positive and 1 gram-negative bacterial infections. Eleven bacterial species were identified based on 16S rRNA gene sequences. Ten (90.9%)of the eleven samples (bacterial species) were identified using our PCR-LF. Five samples were detected in bacterial cultures; two are MSSA, one is Streptococcus agalactiae, one is Escherichia coli, one is Prevotella oralis. We diagnosed 6 samples as clinical infections. Therefore, the sensitivity and specificity of the culture tests were 83% and 100%, respectively, while for PCR-LF, these values were 83% and 83%. Conclusions. PCR-LF is highly sensitive and effective for the rapid diagnosis of joint infection; however, dead bacteria may also be detected. Moreover, because the target bacterial species are limited, clinical diagnosis based on the results of multiple examinations is necessary

Aim. To assess the spread of foot infection and its impact on the outcomes of major amputations of lower extremities in diabetic patients. Method. In a multicentre retrospective and prospective cohort study, we included adult diabetic patients (≥ 18 years) who underwent a major amputation of a lower limb in 5 hospitals between 2000 and 2009, 2012 and 2014. A total of 51 patients were included (of which 27 (52.94%) were men and 24 (47.06%) were women) with the mean age of 65.51 years (SD=16.99). Concomitant section's osseous slice biopsy (BA) and percutaneous bone biopsy of the distal site (BD) were performed during limb amputation. A new surgical set-up and new instruments were used to try and reduce the likelihood of cross-contamination during surgery. A positive culture was defined as the identification of at least 1 species of bacteria not belonging to the skin flora or at least 2 bacteria belonging to the skin flora (CoNS (coagulase negative staphylococci), Corynebacterium spp, Propionibacterium acnes) with the same antibiotic susceptibility profiles. A doubtful culture was defined as the identification of 1 species of bacteria belonging to the skin flora. The patients were followed-up for 1 year. Stump outcomes were assessed on the delay of complete healing, equipment, need of re-intervention and antibiotics. Results. In total, 51 BA were performed during major lower limb amputations (17 above the knee and 34 below the knee) in diabetic patients. Nine (17.65%) bacterial culture results from BA specimens were positive, 7 (13.73%) doubtful and 35 (68.63%) sterile. Before amputation, 23 patients (45.1%) had not received any antibiotics, including 16 (31.37%) with an antibiotic-free interval of 15 days or more. Microorganisms identified in BA were also cultured from the distal site in 33.33% of the cases. Positive BA was associated with prolonged complete stump healing, delay of complete healing (more than 6 months), re-amputation and the need of antibiotics. Conclusions. The microorganisms identified from BA play a role in stump healing in diabetic patients. BA is useful during major limb amputation due to infectious complications and antibiotic therapy could be corrected on the basis of the BA culture results

Aim. Periprosthetic joint infection (PJI) is nowadays the most important problem leading to failure in primary and revision total knee (TKA) and total hip arthroplasty (THA), therefore accurate diagnosis of PJI is necessary. We evaluated a commercial multiplex PCR system1 for diagnosis of PJI in joint aspiration fluids prior to surgery. Method. A total of 32 patients were included in the study. Twenty-four patients had TKA and eight had THA. Joint aspiration fluids were examined by standard bacteriological procedures. Excess material of joint aspirates was frozen at −20°C until testing by multiplex PCR1. Inclusion criteria were a minimum leucocyte count of 2.000 per ml and at least 60% of polymorphonucleaur neutrophils (PNN) in the joint aspiration fluid. Results. For 21 patients with TKA, both standard bacteriological culture and PCR1 were negative. In these patients the mean leucocyte count in the joint fluid was 15.385/ml with 80% PNN. For three patients culture was negative, but PCR1 was positive. In one patient PCR1 detected Corynebacterium sp. which was considered as contamination as this patient had crystal arthropathy; for the second patient Propionibacterium acnes was detected by PCR1, this patient was treated as having an infection of unknown origin in another hospital. For the third patient PCR1 detected Pseudomonas aeruginosa. This patient was known as having chronic P. aeruginosa infection of his TKA and joint aspiration was done shortly after arrest of antibiotic therapy by ciprofloxacin. The mean leucocyte count in the patients with positive PCR was 61.800/ml with 89% PNN. In three of the eight patients with THA, standard bacterial culture and PCR1 were both negative. The mean leucocyte count in joint aspirates of these patients was 10.087/ml with 77% PNN. In five patients with THA, both culture and PCR1 were positive and concordant. In one case culture and PCR1 detected Staphylococcus aureus, and in the other culture and PCR1 detected P. acnes. In two cases culture grew S. epidermidis and PCR1 detected coagulase negative Staphylococcus. In the fifth patient culture grew C. jeikeium and PCR1 detected Corynebacterium spp. Conclusions. We found concordant results for culture and PCR1 in all eight patients with THA and in 22/24 patients (92%) with TKA. Multiplex PCR1 results are available in 4 hours whereas culture results may demand several days. The commercial multiplex PCR system1 designed for diagnosis of implant and tissue infection can be helpful for the diagnosis of PJI. *Unyvero i60©, Curetis Strasbourg, France

Aim. Negative pressure wound treatment (NPWT) has been widely adopted in the management of septic wound complications or prophylactically after large surgeries. Recent publications have indicated the necessity of further investigations to support the use of NPWT with more evidences. Therefore, the purpose of this pilot-study was to investigate the efficacy of VAC-assisted dressing systems in the treatment of septic trauma cases. Method. We analysed data of 16 retrospective cases following traumas and septic soft tissue surgeries around the hip and knee. The collected data consisted of bacterial cultures, inflammatory markers (WBC, CRP/HCRP) and body temperature, taken periodically during treatment. Also recorded were the time periods the vacuum pump was used during treatment. To increase the number of measurements and to facilitate subsequent data analysis, the measurements were interpolated to regularly sampled curves with a sampling rate of one day. We used cross-plots and linear regression analysis to investigate trends in the data: 1) while the vacuum pump was switched on and 2) while it was switched off. Results. The analysis shows that the average WBC and CRP/HCRP values decline in the first days after initiation of the VAC treatment. WBC values decline in the first four days of VAC treatment (linear regression, R. 2. =0.960). CRP/HCRP values decline in the first thirteen days (linear regression, R. 2. =0.952). No meaningful trends were observed in body temperature measurements. Importantly, there is a trend for an increase of WBC and CRP/HCRP, following the 4. th. and 14. th. days, respectively. These findings suggest that the prolonged use of VAC treatment may result in secondary relapses. Conclusions. Our results indicate a marked decrease of inflammatory markers during the first two weeks, confirming the efficacy of NPWT in the management of septic wounds after traumas. Importantly, our analyses also show a periodic relapse with the prolonged use of NPWT. However, further studies are needed with a larger, standardized population to confirm these findings

Introduction. Despite the lack of data regarding the diagnostic validity of synovial aspiration in Girdlestone hips a Girdlestone-aspiration is often performed before reimplantation to detect a possible persistence of infection during two staged revision total hip arthroplasty (THA). The aim of this study was to assess the diagnostic performance of the synovial aspiration in Girdlestone hips, without a PMMA-Spacer, for the detection of infection persistence prior to THA reimplantation. Methods. Seventy four patients undergoing a two staged revision THA surgery between 2006 and 2013 were included in this retrospective cohort study. Both synovial cultures and CRP values were acquired before explantation of the THA and of the Girdlestone hip before reimplantation. An antibiotic holiday of 14 days was observed prior to synovial aspiration. A PJI was defined according to the following criteria: intraarticular presence of pus or a sinus tract, a periprosthetic membrane indicative of infection in the histological analysis, or a positive microbiological isolation in a minimum of two samples. Results. The initial synovial aspiration of the THA, before the endoprosthetic explantation, achieved a sensitivity of merely 68% and a specificity of 50% for the detection of periprosthetic joint infection. The determination of CRP-values surpassed both the sensitivity and specificity values achieved by the synovial aspiration with 95% and 91%, respectively. The synovial aspiration of the Girdlestone hip was only able to produce four positive bacterial cultures. Three of these four positive Girdlestone aspirations were interpreted as legitimate bacterial isolations, while one was classified as a contamination. These four positive bacterial isolations resulted in a sensitivity of 13% and a specificity of 98% for synovial aspiration of the Girdlestone hip. The determination of the CRP-values in Girdlestone hips, prior to THA-reimplantation, achieved a sensitivity of 95% and a specificity of 20%. Conclusion. Our data shows that the synovial aspiration of a Girdlestone hip is of inferior diagnostic validity and poses the risk of contamination. Therefore, we advise against the synovial aspiration of Girdlestone hips during a two stage THA revision, since this can neither reliably confirm nor exclude a persistence of infection

Recent evidence suggests that the microbial community, its spatial distribution and activity play an important role in the prolongation of treatment and healing of chronic infections. Standard bacterial cultures often underestimate the microbial diversity present in chronic infections. This lack of growth is often due to a combination of inadequate growth conditions, prior usage of antibiotics and presence of slow-growing, fastidious, anaerobic or unculturable bacteria living in biofilms. Thus, diagnosis of chronic infections is challenged by lack of appropriate sampling strategies and by limitations in microbiological testing methods. The purpose of this study was to improve sampling and diagnosis of prosthetic joint infections (PJI) and chronic wounds, especially considering the biofilm issue. Systematic sampling, sonication of prosthesis and extended culture were applied on patients with chronic wounds and patients with suspected PJIs. Optimized DNA extraction, quantitative PCR, cloning, next generation sequencing and PNA FISH were applied on the different types of specimens for optimized diagnosis. For further investigation of the microbial pathogenesis, in situ transcriptomics and metabolomics were applied. In both chronic wounds and PJIs, molecular techniques detected a larger diversity of microorganisms than culture methods in several patients. Especially in wounds, molecular methods identified more anaerobic pathogens than culture methods. A heterogeneous distribution of bacteria in various specimens from the same patient was evident for both patient groups. In chronic wounds, multiple biopsies from the same ulcer showed large differences in the abundance of S. aureus and P. aeruginosa at different locations. Transcriptomic and metabolomic analyses indicated the important virulence genes and nutrient acquisition mechanisms of Staphylococcus aureus in situ. As an example, diagnosis and treatment of a patient with a chronic biofilm prosthesis infection persisting for 7 years will be presented. Our studies show that diagnosis of chronic biofilm related infections required multiple specimen types, standardized sampling, extended culture and molecular analysis. Our results are useful for improvement of sampling, analysis and treatment in the clinic. It is our ambition to translate studies on bacterial activity into clinical practice in the future

[Introduction]. Surgical-site-infections (SSI) prolong hospital stay, and they are leading nosocomial cause of morbidity and a source of excess cost. Recently, a waterless hand-rubbing protocol containing aqueous 1% chlorhexidine gluconate was developed before surgery, but there is no literature in orthopaedic surgery. The aim was to compare the SSI rates between waterless hand-rubbing and traditional hand-scrubbing protocol. [Materials and Methods]. STUDY 1: A total of 996 consecutive patients who underwent orthopaedic surgery between August 1, 2012 and January 31, 2014, were screened for SSI within 30 days after surgery. 500 patients from August 1, 2012 to April 1, 2013 were used by traditional hand-scrubbing, and 496 patients from June 1, 2013 to January 1, 2014 were by waterless hand-rubbing. STUDY 2: The twelve operating room staff members were randomly recruited, and the participants were assigned equally to use either a traditional hand-scrubbing protocol or a waterless hand-rubbing on 2 separate days. Washing times were recorded and microorganisms on hands were sampled on bacterial culture plates. Two days after sampling, the grown colonies were counted. [Results]. STUDY 1: SSI rates were 6 of 500 (1.2%) in the traditional hand-scrubbing protocol (2 deep and 4 superficial infecitons) and 4 of 496 (0.9%) in the waterless hand-rubbing protocol (all superficial infections). There were no significant differences. The cost for scrub liquids in one hand-wash was about $2 for traditional hand-scrubbing and less than $1 for waterless hand-rubbing. STUDY 2: Microorganism found on 4 of the 12 plates in the traditional hand-scrubbing protocol and on 0 of 12 in the waterless hand-rubbing protocol. The difference between the groups was statistically significant (p < 0.05). The consuming time for wash was 4 minutes 24 seconds in the traditional hand-scrubbing protocol and 2 minute 43 seconds in the waterless hand-rubbing protocol. [Discussion]. Waterless hand rubbing with aqueous alcoholic solution was as effective as traditional hand scrubbing with antiseptic soap in preventing SSI in orthopaedic surgery. Waterless hand rubbing with liquid aqueous alcoholic solution can be safely, quickly and cost-effectively used as an alternative to traditional hand-scrubbing