Native joint infections in Iceland 2003-2017: an increase in postarthroscopic infections.

OBJECTIVES: Nationwide study on the epidemiology, clinical characteristics and outcomes among patients with native joint infection (NJI) in Iceland, 2003-2017. METHODS: All positive synovial fluid culture results in Iceland were identified and medical records reviewed. RESULTS: A total of 299 NJI (40 children and 259 adults) were diagnosed in Iceland in 2003-2017, with a stable incidence of 6.3 cases/100 000/year, but marked gender difference among adults (33% women vs 67% men, p<0.001). The knee joint was most commonly affected, and Staphylococcus aureus was the most common isolate in both adults and children, followed by various streptococcal species in adults and Kingella kingae in children. NJI was iatrogenic in 34% of adults (88/259) but comprised 45% among 18-65 years and a stable incidence. Incidence of infections following arthroscopic procedures in adults increased significantly compared with the previous decade (9/100 000/year in 1990-2002 vs 25/100 000/year in 2003-2017, p<0.01) with no significant increase seen in risk per procedure. The proportion of postarthroscopic NJI was 0.17% overall but 0.24% for knee arthroscopy. Patients with postarthroscopic infection were more likely to undergo subsequent arthroplasty when compared with other patients with NJI (p=0.008). CONCLUSIONS: The incidence of NJI in Iceland has remained stable. The proportion of iatrogenic infections is high, especially among young adults, with an increase seen in postarthroscopic infections when compared with the previous decade. Although rare, NJI following arthroscopy can be a devastating complication, with significant morbidity and these results, therefore, emphasise the need for firm indications when arthroscopic treatment is considered.

Strain-specific joint invasion and colonization by Lyme disease spirochetes is promoted by outer surface protein C.

Lyme disease, caused by Borrelia burgdorferi, B. afzelii and B. garinii, is a chronic, multi-systemic infection and the spectrum of tissues affected can vary with the Lyme disease strain. For example, whereas B. garinii infection is associated with neurologic manifestations, B. burgdorferi infection is associated with arthritis. The basis for tissue tropism is poorly understood, but has been long hypothesized to involve strain-specific interactions with host components in the target tissue. OspC (outer surface protein C) is a highly variable outer surface protein required for infectivity, and sequence differences in OspC are associated with variation in tissue invasiveness, but whether OspC directly influences tropism is unknown. We found that OspC binds to the extracellular matrix (ECM) components fibronectin and/or dermatan sulfate in an OspC variant-dependent manner. Murine infection by isogenic B. burgdorferi strains differing only in their ospC coding region revealed that two OspC variants capable of binding dermatan sulfate promoted colonization of all tissues tested, including joints. However, an isogenic strain producing OspC from B. garinii strain PBr, which binds fibronectin but not dermatan sulfate, colonized the skin, heart and bladder, but not joints. Moreover, a strain producing an OspC altered to recognize neither fibronectin nor dermatan sulfate displayed dramatically reduced levels of tissue colonization that were indistinguishable from a strain entirely deficient in OspC. Finally, intravital microscopy revealed that this OspC mutant, in contrast to a strain producing wild type OspC, was defective in promoting joint invasion by B. burgdorferi in living mice. We conclude that OspC functions as an ECM-binding adhesin that is required for joint invasion, and that variation in OspC sequence contributes to strain-specific differences in tissue tropism displayed among Lyme disease spirochetes.

Role of asymptomatic bacteriuria on early periprosthetic joint infection after hip hemiarthroplasty. BARIFER randomized clinical trial.

PURPOSE: To evaluate preoperative asymptomatic bacteriuria (ASB) treatment to reduce early-periprosthetic joint infections (early-PJIs) after hip hemiarthroplasty (HHA) for fracture. METHODS: Open-label, multicenter RCT comparing fosfomycin-trometamol versus no intervention with a parallel follow-up cohort without ASB. PRIMARY OUTCOME: early-PJI after HHA. RESULTS: Five hundred ninety-four patients enrolled (mean age 84.3); 152(25%) with ASB (77 treated with fosfomycin-trometamol/75 controls) and 442(75%) without. Despite the study closed without the intended sample size, ASB was not predictive of early-PJI (OR: 1.06 [95%CI: 0.33-3.38]), and its treatment did not modify early-PJI incidence (OR: 1.03 [95%CI: 0.15-7.10]). CONCLUSIONS: Neither preoperative ASB nor its treatment appears to be risk factors of early-PJI after HHA. ClinicalTrials.gov Identifier: Eudra CT 2016-001108-47.

Bone and joint infections caused by Clostridium perfringens: a case series.

The objective of this study was to evaluate antimicrobial therapy outcomes of bone and joint infections (BJI) caused by Clostridium perfringens. We investigated remission of symptoms and the absence of relapse or reinfection during follow-up. Among the 8 patients with C. perfringens BJI, the type of infection was early prosthesis infection (n = 2), osteosynthetic device infection (n = 4), and chronic osteomyeletis (n = 2). Clindamycin-rifampicin combination was given in 4 cases and metronidazole in 4 cases. The overall success rate was 87.5%. Among the 7 patients who completed antibiotic treatment, the success rate was 100%. The clindamycin-rifampicin combination appeared to be effective in patients with C. perfringens BJI.

First report of Kingella kingae diagnosed in pediatric bone and joint infections in Morocco.

BACKGROUND: The progress of diagnostic strategies and molecular methods improved the detection of Kingella kingae in bone and joint infections, and now, Kingella kingae is being increasingly recognized as the most frequent cause of bone and joint infection BJI in early childhood. The main objective of this prospective study is to report the frequency of Kingella Kingae in negative culture bone and joint pediatric infections, and to describe the clinical and biologic features of these children. METHODS: From December 2016 to June 2019, we selected all hospitalized patients with suspected BJI. When culture was negative on the fifth day, children under 10 years were subsequently included in the study, and PCR assay was performed systematically for researching K. kingae specific gene cpn60. Microbial culture and identification were made using standard bacteriological methods. The demographics, clinical, laboratory, radiographic and clinical features were reviewed from medical records. RESULTS: We enrolled 65 children with culture negative BJI, 46 of them having under 10 years old have been screened for the cpn60 gene. Thus, the gene encoding Kingella kingae was positive for 27 BJI cases (58.7%). The mean age of children was 3.02 years, 55.6% were aged 6 months-4 years and 29.6% of them were aged 5-10 years. The male to female ratio was 1.7 and 16 cases (59.26%) occurred during the fall-winter period. The most frequent BJI type was septic arthritis (77.8%) and the most affected sites were knee (51.9%) and hip (37.0%). We recorded a mild clinical picture with normal to mildly raised inflammatory markers. All patients had good clinical and functional outcomes, with no serious orthopedic sequelae.. CONCLUSION: K kingae is an important pathogen of culture-negative BJI in Moroccan children. PCR testing should be performed in culture-negative cases of children not only in the typical age range of 6 months to 4 years. When implemented in the routine clinical microbiology laboratory, a specific K. kingae PCR assay can provide a better diagnostic performance of BJI.

Does Training Innate Immunity Confer Broad-spectrum Protection Against Bone and Joint Infection in a Mouse Model?

BACKGROUND: The innate immune system can recall previous immunologic challenges and thus respond more effectively to subsequent unrelated challenges, a phenomenon called trained immunity. Training the innate immune system before surgery might be a potential option to prevent bone and joint infection. QUESTIONS/PURPOSES: (1) Does the training process cause adverse effects such as fever or organ injury? (2) Does training the innate immune system confer broad-spectrum protection against bone and joint infection in a mouse model? (3) Does trained immunity remain effective for up to 8 weeks in this mouse model? METHODS: After randomization and group information blinding, we trained the innate immune system of C57BL/6 mice (n = 20 for each group) by intravenously injecting them with either 0.1 mg of zymosan (a toll-like receptor 2 agonist), 0.1 mg of lipopolysaccharide (a toll-like receptor 4 agonist), or normal saline (control). For assessing the host response and possible organ injury after training and infection challenge, we monitored rectal temperature, collected blood to determine leukocyte counts, and performed biochemical and proinflammatory cytokine analyses. After 2 weeks, we then assessed whether trained immunity could prevent infections in an intraarticular implant model subjected to a local or systemic challenge with a broad spectrum of bacterial species (Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Streptococcus pyogenes, or Pseudomonas aeruginosa) in terms of culture-positive rate and colony counts. The proportion of culture-positive joint samples from trained and control groups were compared after 4 weeks. Finally, we increased the interval between training and bacterial challenge up to 8 weeks to assess the durability of training efficacies. RESULTS: Training with zymosan and lipopolysaccharide caused mild and transient stress in host animals in terms of elevated rectal temperature and higher blood urea nitrogen, creatinine, alanine aminotransferase, and aspartate aminotransferase levels. Trained mice had fewer culture-positive joint samples after local inoculation with S. aureus (control: 100% [20 of 20]; zymosan: 55% [11 of 20], relative risk 0.55 [95% CI 0.37 to 0.82]; p = 0.001; lipopolysaccharide: 60% [12 of 20], RR 0.60 [95% CI 0.42 to 0.86]; p = 0.003) and systemic challenge with S. aureus (control: 70% [14 of 20]; zymosan: 15% [3 of 20], RR 0.21 [95% CI 0.07 to 0.63]; p = 0.001; lipopolysaccharide: 15% [3 of 20], RR 0.21 [95% CI 0.07 to 0.63]; p = 0.001) than controls. We observed similar patterns of enhanced protection against local and systemic challenge of E. coli, E. faecalis, S. pyogenes, and P. aeruginosa. Zymosan-trained mice were more effectively protected against both local (control: 20 of 20 [100%], zymosan: 14 of 20 [70%], RR 0.70 [95% CI 0.53 to 0.93]; p = 0.02) and systemic (control: 70% [14 of 20]; zymosan: 30% [6 of 20], RR 0.43 [95% CI 0.21 to 0.89]; p = 0.03) challenge with S. aureus for up to 8 weeks than controls. CONCLUSIONS: Trained immunity confers mild stress and broad-spectrum protection against bone and joint infection in a mouse model. The protection conferred by immunity training lasted up to 8 weeks in this mouse model. The results of the current research support further study of this presurgical strategy to mitigate bone and joint infection in other large animal models. CLINICAL RELEVANCE: If large animal models substantiate the efficacy and safety of presurgical immunity training-based strategies, clinical trials would be then warranted to translate this strategy into clinical practice.

Multidisciplinary management of the bone and joint infection complicating treatment of an open fracture of the lower limb.

Bone and joint infections (BJI) of the lower limb can cause functional sequelae and in some cases have an impact on patient's life prognostic. One of the main objectives of multidisciplinary consultation team meetings (MTM) in the treatment of bone and joint infections is to provide an appropriate medical-surgical care, pooling skills of different organ specialists: infectious disease physicians, microbiologists, orthopedic surgeons and plastic surgeons. Treatment is based on aggressive debridement, bone stabilization, adequate antibiotic therapy, long-term coverage of the loss of skin substance and close clinical monitoring. The authors present their multidisciplinary diagnostic and therapeutic approaches to BJI complicating an open fracture at a referent center in the management of complex bone and joint infections.

Added diagnostic value of broad-range 16S PCR on periprosthetic tissue and clinical specimens from other normally sterile body sites.

AIMS: Evaluation of 16S PCR in addition to the standard culture to improve the pathogen detection rate in clinical specimens. METHODS AND RESULTS: Microbiological culture and direct 16S PCR was performed on specimens from suspected prosthetic joint infection patients (cohort-1) and on tissues and fluids from other normally sterile body sites (cohort-2). Based on clinical and microbiological data, the detection rate for both methods was assessed, assuming no superiority of either 16S PCR or culture. In cohort-1, 469 specimens were obtained. Culture was positive in 170 (36·2%) specimens, 16S PCR detected 70 (41·2%) of those pathogens. Additionally, 16S PCR detected pathogens in 13 of 299 (4·3%) culture-negative specimens. In cohort-2, pathogens were cultured in 52 of 430 (12·1%) specimens and 16S PCR revealed those pathogens in 32 (61·5%) specimens. 16S PCR detected pathogens in 31 of 378 (8·2%) culture-negative specimens. CONCLUSIONS: Overall, the yield with 16S PCR was low. For cohort-1 16S PCR detected pathogens in 4·3% of culture-negative specimens, where this was 8·2% for cohort-2. SIGNIFICANCE AND IMPACT OF THE STUDY: Although direct 16S PCR cannot replace culture, it may offer a valuable additional diagnostic option for detection of difficult to culture micro-organisms in culture-negative clinical specimens.

Molecular Epidemiology of Staphylococcus aureus in Skin and Soft Tissue Infections and Bone and Joint Infections in Korean Children.

BACKGROUND: Community acquired-methicillin resistant Staphylococcus aureus (MRSA) clones, including ST1, ST8, and ST30 are reported worldwide. However, data among Korean children are limited. Thus, we investigated the molecular characteristics of S. aureus among children in Korea. METHODS: S. aureus isolated from Korean children diagnosed with skin and soft tissue infection (SSTI) or bone and joint infection due to S. aureus infection at Seoul National University Bundang Hospital, from August 2010 to November 2016, were analyzed for multilocus sequence type (ST) and SCCmec typing. Polymerase chain reaction of Panton-Valentine leukocidin (PVL), qac A/B, smr and mupA genes were also performed. Electronic medical records were reviewed for clinical data and antibiotic susceptibility results. Cases were classified into three groups: health care-associated community-onset (HACO) infections, hospital-onset (HO) infections, and community-acquired (CA) infections. RESULTS: A total of 67 strains from children with SSTI (41/67, 61.2%) and bone and joint infection (26/67, 38.8%) were included. Among all isolates, 29.9% (20/67) were MRSA, and 70% (14/20) were classified as CA, 20% (4/20) as HACO and 10% (2/20) as HO infections. MRSA rate according to disease was 34.1% (14/41) for SSTI and 23.1% (6/26) for bone and joint infection. MRSA strains included ST72-SCCmec IV (14/20, 70.0%), ST5-SCCmec II (3/20, 15.0%) and ST1-SCCmec IV (2/20, 10.0%). ST30 was the most common cause of SSTI and bone and joint infections and 96.6% (28/29) were methicillin-susceptible Staphylococcus aureus (MSSA). PVL genes were detected in 3 strains (3.8%, ST30-SCCmec IV n = 1, MSSA ST30 n = 2), qac A/B in 3 (MRSA = 3), smr in 3 (MSSA = 1, MRSA = 2) and mupA in 7 (MRSA = 5, MSSA = 2). CONCLUSION: Molecular epidemiology of S. aureus in Korean children with SSTI and bone and joint infection showed that ST30 was predominant and mostly MSSA. Among MRSA, ST72-SCCmec type IV was the most common strain.

Suppressive antibiotic therapy with oral tetracyclines for prosthetic joint infections: a retrospective study of 78 patients.

PURPOSE: This study aimed at describing the use of oral cyclines (i.e., doxycycline and minocycline) as suppressive antibiotic therapy (SAT) in patients with periprosthetic joint infections (PJIs). METHODS: Medical charts of all patients with surgical revisions for PJIs who were given cycline-based SAT because of a high failure of various origins were reviewed. Data regarding tolerability and effectiveness of cycline-based SAT were analysed. RESULTS: Seventy-eight patients of mean age 64 ± 17 years received cycline-base SAT in the period from January 2006 to January 2014. PJIs involved the knee in 37 patients (47%), the hip in 35 (45%), the elbow in 4 (5%), and the shoulder in 2 (3%) and were qualified as early in 31 patients (39.7%). Staphylococcus spp. were the most common pathogens accounting for 72.1% of the total number of bacterial strains identified. All included patients had surgery which consisted in debridement and implant retention in 59 of them (75.6%). Doxycycline and minocycline were prescribed as SAT in 72 (92%) and 6 (8%) patients, respectively. Adverse events were reported in 14 patients (18%), leading to SAT discontinuation in 6 of them (8%). After a mean follow-up of 1020 ± 597 days, a total of 22 (28.2%) patients had failed including 3 cases (3.8%) with documented acquisition of tetracycline resistance in initial pathogen(s). CONCLUSIONS: Our results suggest that oral cyclines used as SAT in patients treated for PJI have an acceptable tolerability and effectiveness and appear to be a reasonable option in this setting.

Tubercular prosthetic joint infection: two case reports and literature review.

PURPOSE: Tubercular prosthetic joint infection (TB-PJI) is an uncommon complication. Lack of evidence of systemic tuberculosis and clinical suspicion could bring a delay in the time of the diagnosis. The aims of this study are to underline the importance of awareness and suspicion of mycobacterial infection in the differential diagnosis in PJI and to evaluate the appropriateness of different therapeutic options. METHODS: Case report and literature review. RESULTS: We report two cases of TB-PJI after total knee arthroplasty in Caucasian patients without prior history of tubercular disease or exposure. In both cases, the diagnosis was obtained years after the onset of symptoms. Despite that, both patients improved during antitubercular treatment (a four-drug regimen consisting of rifampicin, isoniazid, ethambutol, and pyrazinamide for 2 months, followed by rifampicin and isoniazid). Moreover, after an 18-month course of treatment, there was no need for surgical therapy. The result of the literature review allows us to identify 64 cases of TB-PJI. Many differences in both medical and surgical management have been found, among those reviewed cases. CONCLUSIONS: Considering our experience and the literature review, we recommend considering a conservative approach (debridement and adequate antituberculous chemotherapy) as a suitable and safe option.

In vitro antibacterial activity of bioactive glass S53P4 on multiresistant pathogens causing osteomyelitis and prosthetic joint infection.

BACKGROUND: Conventional local treatment for medullary osteomyelitis (OM) includes insertion of antibiotic-loaded polymethylmethacrylate (PMMA) cement. Nevertheless, PMMA may delivery irregular concentration of antibiotic to surrounding tissue. We aimed to compare the in vitro antibacterial activity of Bioactive Glass (BAG) S53P4, which is a compound showing local antibacterial activity, to that of antibiotic-loaded PMMA against multidrug resistant bacteria from OM isolates. METHODS: We studied convenience samples of multidrug resistant (MDR) microorganisms obtained from patients presenting OM and prosthetic joint infection (PJI). Mixtures containing tryptic soy broth (TSB) and inert glass beads (2 mm), BAG-S53P4 granules (0.5-0.8 mm and < 45 mm) and Gentamicin or Vancomycin-loaded PMMA beads were inoculated with methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus (MR-CoNS), Pseudomonas aeruginosa or Klebsiella pneumoniae isolates. Glass beads (2.0 mm) were used as a control. Antibacterial activity was evaluated by means of time-kill curve, through seeding the strains on blood agar plates, and subsequently performing colony counts after 24, 48, 72, 96, 120 and 168 h of incubation. Differences between groups were evaluated by means of two-way analysis of variance (ANOVA) and Bonferroni's t test. RESULTS: Inhibition of bacterial growth started soon after 48 h of incubation, reached zero CFU/ml between 120 and 168 h of incubation for both antibiotic-loaded PMMA and BAG S53P4 groups, in comparison with inert glass (p < 0.05). No difference regarding time-kill curves between antibiotic-loaded PMMA and BAG S53P4 was observed. CONCLUSIONS: BAG S53P4 presented antibacterial properties as much as antibiotic-loaded PMMA for MDR bacteria producing OM and PJI.

Hemolytic strains of Propionibacterium acnes do not demonstrate greater pathogenicity in periprosthetic shoulder infections.

BACKGROUND: Hemolysis has been suggested as a feature conferring increased pathogenicity to certain Propionibacterium acnes strains in the setting of shoulder infection. The purpose of this study was to compare the virulence of hemolytic and nonhemolytic P acnes strains in patients undergoing revision shoulder arthroplasty. METHODS: Thirty-nine patients with at least 1 positive culture growth for P acnes at the time of revision surgery were identified with P acnes isolates available for hemolysis testing. Patients were grouped into those with P acnes isolates positive (n = 20) and negative (n = 19) for hemolysis. The groups were retrospectively compared based on objective perioperative findings around the time of revision surgery and the postoperative clinical course, including the need for revision surgery. All cases were classified into categories of infection (definite infection, probable infection, and probable contaminant) based on objective perioperative criteria. RESULTS: The presence of hemolysis was not significantly associated with an increased likelihood of infection (P = .968). Hemolysis demonstrated a 75% sensitivity and 26% specificity for determining infection (definite infection and probable infection categories). The hemolytic and nonhemolytic groups showed no difference regarding preoperative serum erythrocyte sedimentation rate and/or C-reactive protein level (P = .70), number of positive cultures (P = .395), time to positive culture (P = .302), and presence of positive frozen section findings (P = .501). Postoperatively, clindamycin resistance, shoulder function, and the rate of reoperation were not significantly different between the hemolytic and nonhemolytic groups. CONCLUSION: The presence of hemolysis was not associated with increased pathogenicity in patients with P acnes-positive cultures following revision shoulder arthroplasty, when assessed by objective perioperative criteria and the postoperative clinical course.

Acute periprosthetic joint infection due to Fusobacterium nucleatum in a non-immunocompromised patient. Failure using a Debridement, Antibiotics + Implant retention approach.

Fusobacterium nucleatum is an obligately anaerobic gram-negative rod, a component of the microbiome of the oropharynx and the gastrointestinal and urogenital tracts, causing an array of human infections which often include periodontal pathologies. As far as we know, there are no previous publications about acute periprosthetic joint infection due to Fusobacterium sp.; we report the first case in the medical literature of an aggressive, acute knee prosthetic infection due to F. nucleatum in a non-immunocompromised patient, unsuccessfully treated with a DAIR approach (Debridement + Antibiotics + Implant Retention).

Second-site prosthetic joint infection in patients with multiple prosthetic joints.

INTRODUCTION: Prosthetic joint infections (PJIs) are among the most serious complications in arthroplasty. A second-site PJI in patients with multiple prosthetic joints increases morbidity, with many requiring further revision procedures. We aimed to establish why some patients with multiple joints develop second-site infections. METHODS: Our institution's arthroplasty database was reviewed from 2004 to 2017. All PJIs were identified, and all patients with more than one prosthetic joint in situ were included. We recorded risk factors, causative organisms, number of procedures and length of stay. RESULTS: Forty-four patients meeting the criteria were identified. Four patients (9.1%) developed second-site infection. Eight patients (18.2%) developed re-infection of the primary PJI. Positive MRSA carrier status and PJI of a total knee replacement were associated with an increased risk of a second episode of infection. Patients who developed further infection had more frequent admission and longer lengths of stay than isolated PJIs. DISCUSSION: Higher morbidity and use of hospital resources are associated with this cohort of patients. PJIs in total knee replacements and positive MRSA status are associated with higher rates of second infection. Identifying this vulnerable cohort of patients at an early stage is critical to ensure measures are taken to reduce the risks of further infection.

Population pharmacokinetics of rifampicin in adult patients with osteoarticular infections: interaction with fusidic acid.

AIMS: Rifampicin represents the key antibiotic for the management of osteoarticular infections. An important pharmacokinetic variability has already been described, particularly for absorption and metabolism. All previous pharmacokinetic studies have been focused only on patients treated for tuberculosis. The objective of the present study was to describe a population pharmacokinetic model of rifampicin in patients with staphylococcal osteoarticular infections, which has not been investigated to date. METHOD: Rifampicin concentrations were collected retrospectively from 62 patients treated with oral rifampicin 300 mg three times daily. Plasma concentration-time data were analysed using NONMEM to estimate population pharmacokinetic parameters. Demographic data, infection characteristics and antibiotics taken in addition to rifampicin antibiotics were investigated as covariates. RESULTS: A one-compartment model, coupled to a transit absorption model, best described the rifampicin data. Fusidic acid coadministration was identified as a covariate in rifampicin pharmacokinetic parameters. The apparent clearance and apparent central volume of distribution mean values [95% confidence interval (CI)] were 5.1 1 h-1 (1.2, 8.2 1 h-1 )/23.8 l (8.9, 38.7 l) and 13.7 1 h-1 (10.6, 18.0 1 h-1 )/61.1 1 (40.8, 129.0 1) for patients with and without administration of fusidic acid, respectively. Interindividual variability (95% CI) in the apparent clearance and apparent central volume of distribution were 72.9% (49.5, 86.0%) and 59.1% (5.5, 105.4%), respectively. Residual variability was 2.3 mg l-1 (1.6, 2.6 mg l-1 ). CONCLUSION: We developed the first population pharmacokinetic model of rifampicin in patients with osteoarticular infections. Our model demonstrated that fusidic acid affects rifampicin pharmacokinetics, leading to potential high drug exposure. This finding suggests that fusidic acid dosing regimens should be reconsidered.

Influence of molecular characteristics in the prognosis of methicillin-resistant Staphylococcus aureus prosthetic joint infections: beyond the species and the antibiogram.

We have explored the relationship of phenotypic (antibiogram, ß-haemolysis, agr functionality, biofilm formation) and genotypic characteristics on the prognosis of 18 cases of methicillin-resistant S. aureus prosthetic joint infection (2005-2015). All isolates belonged to CC5, and had agr type II. This pilot study suggests that phage-borne genes belonging to the immune evasion cluster (chp, sak and scn) were more frequent among episodes with treatment failure (80.0 vs. 37.5%).

The Microbiome and Bone and Joint Disease.

PURPOSE OF REVIEW: Changes in the constituents and activity of the microbiome have been associated with a number of conditions linked to bone and joint disease. This review concentrates on ways in which the microbiome is known to influence osteoarthritis and osteoporosis. RECENT FINDINGS: Animal studies have demonstrated that changes in the microbiome can mediate the effects of obesity on cartilage degeneration. Additionally, the microbiome influences the amount of the bone (bone quantity), as well as bone tissue material properties (bone quality). Early clinical findings support the effects of the microbiome on osteoporosis and osteoarthritis. Although animal studies implicate the microbiome in the development of bone and joint disease, available results are limited and can be conflicting. Further investigation of the mechanisms linking from changes in the microbiome to alterations in the bones and joints are necessary.

Algorithm to Diagnose Delayed and Late PJI: Role of Joint Aspiration.

Total Joint Arthroplasty (TJA) continues to gain acceptance as the standard of care for the treatment of severe degenerative joint disease, and is considered one of the most successful surgical interventions in the history of medicine. A devastating complication after TJA is infection. Periprosthetic joint infection (PJI), represents one of the major causes of failure and remains a significant challenge facing orthopaedics today. PJI usually requires additional surgery including revision of the implants, fusion or amputations causing tremendous patient suffering but also a heavy health economics burden. PJI is at the origin of around 20-25 % of total knee arthroplasty (Bozic et al. 2010; de Gorter et al. 2015; Sundberg et al. 2015) and 12-15 % of total hip arthroplasty (Bozic et al. 2009; Garellick et al. 2014; de Gorter et al. 2015) failures.