Aims. The aims of this study were to: 1) report on a cohort of skeletally mature patients with native hip and knee septic arthritis over a 14-year period; 2) to determine the rate of joint failure in patients who had experienced an episode of hip or knee septic arthritis; and 3) to assess the outcome following septic arthritis relative to the infecting organism, whether those patients infected by Staphylococcus aureus would be more likely to have adverse outcomes than those infected by other organisms. Methods. All microbiological samples from joint aspirations between March 2000 and December 2014 at our institution were reviewed in order to identify cases of culture-proven septic arthritis. Cases in children (aged < 16 years) and prosthetic joints were excluded. Data were abstracted on age at diagnosis, sex, joint affected (hip or knee), type of organisms isolated, cause of septic arthritis, comorbidities within the Charlson Comorbidity Index (CCI), details of treatment, and outcome. Results. A total of 142 patients were confirmed to have had an episode of septic arthritis in a native hip (n = 17) or knee joint (n = 125). S. aureus accounted for 57.7% of all hip and knee joint infections. There were 13 inpatient deaths attributed to septic arthritis. The median age of the patients who died was 77.5 (46.9 to 92.2) and their median age-adjusted CCI was 8 (6 to 12). A failure of the joint occurred in 26 knees (21%) and nine hips (53%). Of the knee joints infected by S. aureus (n = 71), 23 knees (32%) went into failure of joint, whereas of those infected by other organisms (n = 54), only three knees (6%) failed. Conclusion. Based on our study findings, hip and knee septic arthritis long-term outcomes were substantially worse than their immediate outcome suggested. Failure of knee joint is 6.1 times more likely to occur in those infected with S. aureus. Cite this article: Bone Jt Open 2024;5(9):785–792

Aims. Staphylococcus aureus is a major cause of septic arthritis, and in vitro studies suggest α haemolysin (Hla) is responsible for chondrocyte death. We used an in vivo murine joint model to compare inoculation with wild type S. aureus 8325-4 with a Hla-deficient strain DU1090 on chondrocyte viability, tissue histology, and joint biomechanics. The aim was to compare the actions of S. aureus Hla alone with those of the animal’s immune response to infection. Methods. Adult male C57Bl/6 mice (n = 75) were randomized into three groups to receive 1.0 to 1.4 × 10. 7. colony-forming units (CFUs)/ml of 8325-4, DU1090, or saline into the right stifle joint. Chondrocyte death was assessed by confocal microscopy. Histological changes to inoculated joints were graded for inflammatory responses along with gait, weight changes, and limb swelling. Results. Chondrocyte death was greater with 8325-4 (96.2% (SD 5.5%); p < 0.001) than DU1090 (28.9% (SD 16.0%); p = 0.009) and both were higher than controls (3.8% (SD 1.2%)). Histology revealed cartilage/bone damage with 8325-4 or DU1090 compared to controls (p = 0.010). Both infected groups lost weight (p = 0.006 for both) and experienced limb swelling (p = 0.043 and p = 0.018, respectively). Joints inoculated with bacteria showed significant alterations in gait cycle with a decreased stance phase, increased swing phase, and a corresponding decrease in swing speed. Conclusion. Murine joints inoculated with Hla-producing 8325-4 experienced significantly more chondrocyte death than those with DU1090, which lack the toxin. This was despite similar immune responses, indicating that Hla was the major cause of chondrocyte death. Hla-deficient DU1090 also elevated chondrocyte death compared to controls, suggesting a smaller additional deleterious role of the immune system on cartilage. Cite this article: Bone Joint Res 2022;11(9):669–678

Introduction and Objective. Septic arthritis is an acute infective presentation of the joint calling for urgent intervention, thus making the differential diagnosis process difficult. An increase in temperature in the area containing the suspected septic arthritis is one of the clinically important findings. In this study, it was aimed to investigate whether or not the temperature changes obtained through thermal camera can be used as a new additional diagnostic tool in the differential diagnosis of septic arthritis. Materials and Methods. The study was approved by the local ethics committee as a prospective cohort. A total of 49 patients, 15 septic and 34 non-septic ones, both male and female ones from all ages admitted to the emergency room or evaluated with the consultation of another clinics who were also present with a pre-diagnosis of arthritis (septic or non-septic) in the knee (with complaints of redness, swelling, pain, effusion, increased temperature, edema, and inability to walk) were included in the study. The patients with non-joint inflammatory problems and a history of surgery in the same joint were excluded from the study. The temperature increase in the joint area with suspected septic arthritis was observed, and the difference in temperature changes of this suspicious area with the joint area of the contralateral extremity was compared after which the diagnosis of septic arthritis was confirmed by taking culture with routine intra-articular fluid aspiration, which is the gold standard for definitive diagnosis. Results. The mean age of the patients was 39.89 ± 27.65°C. A significant difference was found between the group with and without septit arthritis in terms of ASO, sedimentation, and leukocyte increase in the analysis of joint fluid (p <0.05). When the thermal measurements were compared, the mean temperature was 37.93°C in the septic group, while it was 36.79°C in the non-septic group, which showed a significant difference (p <0.000∗). The mean temperature difference in both joints was 3.40°C in the septic group, while 0.94°C in the non-septic group (p <0.000∗). While the mean temperature was 37.10°C in the group with septit arthritis, it was measured to be 35.89 °C in the group without (p <0.020). A very strong positive correlation was found between the difference between the mean temperatures of both groups and the values of the hottest and coldest temperature points (r = 0.960, r = 0.902). Conclusions. In the diagnosis of septic arthritis, a thermal imager can be used as a non-invasive diagnostic tool. With the help of this device, a quantitative value, in addition to palpation, can be given to the local temperature increase in the joint, which is an important finding in the clinic of septic arthritis. In future studies, specially designed thermal devices developed with special software for septic arthritis can be developed

Septic arthritis following anterior cruciate ligament reconstruction (ACLR) is a rare and serious complication. Previous studies have shown that septic arthritis is associated with inferior outcome of ACLR. Despite that, there is no standardized treatment protocol, and the course of the disease has mainly been studied within single institutions with a small number of patients. The aim of the present study is to describe the course of septic arthritis following ACLR in a large nationwide cohort. The hypothesis was that the clinical presentation of septic arthritis following ACLR varies according to the infectious agent. The present cohort represents patients with septic arthritis identified in a previous study that analyzed compensation claims reported to the Swedish national insurance company (Löf) in 2005–2014 (1). The diagnosis was confirmed by medical experts at Löf after review of medical records. We conducted a comprehensive analysis of the medical records as well as data available from the Swedish National Knee Ligament Registry (SNKLR) for the study group. The study involved 158 patients who received compensation due to developing septic arhtirits. 94 (59.9%) patients were infected with Coagulase negative staphylococci (CoNS), and 25 patients by Staphyolococcus Aureus (S.Aureus) (15.9%). There was a significant difference between the groups regarding Maximum CRP (p<0.001), and duration between ACLR and first washout operation (p<0.005). S.aureus group had the higest maximum CRP (281) and the shortest duration between ACLR and first washout operation (12 days). The Clinical presentation of septic arthritis following ACLR can vary according to the agent causing the infection, and low virulent agents are responsible for the majority of the infections. Clinicians need to be aware of these differences and consider them when making diagnosis or treatment decisions

Introduction. Septic arthritis of the native knee often results in irreversible joint damage leading to the need for a total knee arthroplasty (TKA). This study examines the mid-term risk of periprosthetic joint infection (PJI), aseptic revision, any revision, and any reoperation in primary TKAs after septic arthritis of the native knee compared to a control cohort of primary TKAs performed for osteoarthritis (OA). Methods. We retrospectively identified 215 primary TKAs performed between 1971 and 2016 at a single institution following septic arthritis of the native knee. Eighty-two percent (177 cases) were treated in a single setting, whereas a two-stage exchange arthroplasty protocol was utilized in 18% (39 cases) for ongoing or suspected active native knee septic arthritis. Each case was matched 1:1 based on age, sex, body mass index (BMI), and surgical year to a primary TKA for OA. Mean age and BMI were 63 years and 30 kg/m2, respectively. Mean follow-up was 9 years. Results. Survivorship free from any infection (inclusive of PJI and wound infections) at 10 years was 87% in the septic arthritis cohort and 98% for the OA cohort (HR=6.5, p<0.01). Survivorship free of PJI at 10 years was 90% in the septic arthritis and 99% in the OA group (HR=6; p<0.01). There was no difference in the rate of infection when TKA occurred within 5 years of a septic arthritis diagnosis compared to a diagnosis that occurred >5 years from the TKA. The survivorship free of aseptic revision at 10 years was 83% for the septic arthritis cohort and 93% for the OA cohort (HR=2.5, p<0.01). When combining the above survivorships free of aseptic and septic revisions, the survivorship free of any revision at 10 years was 78% in the septic arthritis cohort and 91% in the OA cohort (HR=3, p<0.01). The 10-year survivorship free of any reoperation was 61% in septic arthritis group and 84% in the OA group (HR=3; p<0.01). Preoperative and 2-year postoperative Knee Society scores were similar between groups (p=0.16 and p=0.19, respectively). Conclusion. There was a 6-fold increased risk of PJI in patients undergoing TKA with prior history of septic arthritis when compared to controls who had a TKA for OA, with a cumulative incidence of 9% at 10 years. Moreover, the 10-year survivorships free of aseptic revision, any revision, and any reoperation were significantly worse in the septic arthritis cohort. Summary. A history of septic arthritis prior to primary TKA allows for satisfactory clinical outcomes, but patients had increased risk of PJI, aseptic revision, any revision, and any reoperation compared to a control cohort

A hot swollen joint is a commonly encountered condition in clinical practice. With a broad range of differentials, septic arthritis (SA) is perhaps one of the most concerning. Treated by culture-specific antibiotics and arthroscopic lavage, some patients require multiple washouts. We aimed to determine:. (1) What are the risk factors for development of SA?. (2) What are the risk factors for repeat washout in SA patients?. (3) What are the important clinical differences between a periprosthetic joint infection (PJI) and SA cohort?. All patients presenting to the emergency department, orthopaedic, and rheumatology clinics between January 2020 to January 2021 with a hot, swollen joint were retrospectively evaluated. Patients with previous trauma on the ipsilateral joint, with data missing from their medical records in any of the variables required for analysis, <24 months follow-up were excluded. Variables of interest in the three-month period preceding the diagnosis of SA were compared between SA and non-SA patients. Factors with a p-value of p<0.100 in univariate analysis were included in a stepwise multivariate logistic regression model. Similar analyses were performed to compare SA patients with multiple washouts with those needing one washout. Demographical and clinical data for PJI patients were collected to delineate important differences with SA cohort. 211 patients were included (SA:28;PJI:24;pseudogout:32;gout:26;others:101). Multivariate analysis showed rheumatoid arthritis (RA), skin infection, and liver disease were risk factors for SA. Amongst patients with septic arthritis, multivariate analysis showed that WBC levels above normal limits (3.6-10.5×109 cells/L) and RA were risk factors for multiple washouts. Between the SA and PJI cohorts, BMI (p=0.002) was significantly lower in the former, whilst WBC level (p=0.023) and CRP (p<0.0001) was significantly higher in the former. Early diagnosis of septic arthritis requires understanding the risk factors, namely RA, skin infection, and liver disease. Considering PJI and septic arthritis as the same entity can lead to wrong clinical judgement, and clinicians should be aware of important differences. We believe that the models in this study are of prognostic value to clinicians who are presented with the common presenting compliant of a hot swollen joint

Aim. Synovial fluid D-lactate may be useful for diagnosing septic arthritis (SA) as this biomarker is almost exclusively produced by bacteria. We evaluated the performance of synovial fluid D-lactate and determined its optimal cut-off value for diagnosing SA. Method. Consecutive patients with suspicion of septic arthritis were prospectively included. They underwent joint aspiration and synovial fluid was collected for culture, leukocyte count and D-lactate concentration (by spectrophotometry). Youden's J statistic was used for determining optimal D-lactate cut-off value on the receiver operating characteristic (ROC) curve by maximizing sensitivity and specificity. Results. A total of 155 patients were included. Using institutional criteria, 21 patients (14%) were diagnosed with SA and 134 (86%) patients with aseptic arthropathy, out of which 43 (27%) had osteoarthrosis, 80 (52%) had rheumatic arthropathy and 11 (7%) reactive arthritis. The optimal cut-off of synovial fluid D-lactate to differentiate SA from aseptic cases was 0,035 mmol/l. Synovial fluid D-lactate had a sensitivity 90% (95% CI: 70–99%) and specificity 87% (95% CI: 80–92%) compared to leukocyte count with sensitivity 81% (95% CI: 60–95%) and specificity 83% (95% CI: 76–90%). Culture was positive in only 17 (80%) out of 21 patients with SA. Conclusions. The synovial fluid D-lactate showed high sensitivity and specificity for diagnosis of SA which was higher than the current gold standard of diagnosis (culture and leukocyte count). The high sensitivity makes this biomarker useful as a point-of-care screening test for SA

Shoulder septic arthritis is uncommon and frequently misdiagnosed, resulting in severe consequences. This study evaluated the demographics, bacteriological profile, antibiotic susceptibility, treatment regimens, and clinical outcomes. This is a 10-year retrospective observational analysis of 30 patients (20 males and 10 females) who were treated for septic arthritis of the shoulder. The data collecting process utilised clinical records, laboratory archives, and x-ray archives. We gathered demographic information, pre- and post-intervention clinical data, serum biochemical markers, and the results of imaging examinations. All patients had a surgical arthrotomy and joint debridement in the operating room, and specimens were taken for culture and sensitivity testing. The specimens were cultivated for at least seventy-two hours. Shoulder joint ranges of motion, comorbidities, and the presence of osteomyelitis were assessed clinically to determine the outcome. All statistical analyses were conducted using the STATA 17 statistical software. Analysis of correlation between categorical variables was performed using the chi-squared test. The majority of the study patients were black Africans (97%). The age range of the group was from 8 days to 17 years. At presentation, 33% of patients had a low-grade fever, whereas the majority (60%) had normal body temperature. The average length of symptoms was 3.9 days (ranged from 1 day to 15 days), and the majority of patients had an increased white cell count (83%) and C-reactive protein (98%). There was accumulation of fluid in the joint of all individuals who received shoulder ultrasound imaging. We noted a significant incidence of gram-positive cocci, which were mostly susceptible to first-line antibiotics. Shoulder stiffness affected 63% of patients and chronic osteomyelitis affected 50% of individuals. Neither the severity nor the duration of the symptoms was related to an increased risk of osteomyelitis. The results of this study revealed that the clinical characteristics and bacterial profile of septic arthritis of the shoulder conform to typical patterns. The likelihood of osteomyelitis and an unfavourable prognosis is considerable

Aim. Septic arthritis is a painful infection of articular joints that is typically treated by irrigation & debridement along with antibiotic therapy. There is debate amongst the medical community whether antibiotic administration should be delayed until fluid cultures have been taken to improve culture yield. However, delaying antibiotics can also have negative consequences, including joint destruction and sepsis. Therefore, the purposes of this study were to determine: 1) whether delayed antibiotic treatment affects culture yield and prognosis and 2) if the culture yield of patients treated for septic arthritis differs for hip, knee, and shoulder based on timing of antibiotic administration. Method. A retrospective analysis was conducted on 111 patients with septic arthritis of the hip, knee, or shoulder admitted from 3/2016 to 11/2018. In patients with multiple septic joints, each joint was analyzed individually (n=122). Diagnosis was determined by the treatment of irrigation & debridement and/or a positive culture. Patients without all intervention times recorded or with periprosthetic joint infection were excluded. Demographics, laboratory tests, culture results, and intervention times were obtained through chart review. Patients were grouped based on antibiotic therapy timing: >24 hours prior to arthrocentesis (Group 1), between 24 hours and 1 hour prior (Group 2), and 1 hour prior to post-arthrocentesis (Group 3). Analysis was conducted using chi-squared tests. Results. The mean age of each group were similar: Group 1 (n=38) 55.7 years, Group 2 (n=20) 57.2 years, and Group 3 (n=64) 54.8 years. No difference was observed in culture sensitivity between groups (p=0.825) with 71.1% (27/38) positive cultures in Group 1, 75% (15/20) in Group 2, and 76.6% (49/64) in Group 3. Similarly, frequency of related readmissions within 90 days (p=0.863) did not significantly vary: 26.3% (10/38) in Group 1, 20% (4/20) in Group 2, and 25% (16/64) in Group 3. Additionally, there were no significant differences in culture sensitivity in the knee (p=0.618; Groups: 87.5%, 75%, 70.6%), shoulder (p=0.517; Groups: 77.8%, 66.7%, 90%), and hip (p=0.362; Groups: 61.9%, 80%, 80%). Conclusions. Culture sensitivities and rates of readmission were similar for all patients regardless of antibiotic administration timing. These results suggest that antibiotic administration should not be delayed in septic arthritis to improve culture yield. However, the data does not suggest that early antibiotic administration will result in better clinical outcomes by lowering readmission rates. Further research is needed to better determine the clinical benefits that early administration of antibiotics may have on patient outcomes

Aim. Prompt recognition and identification of the causative microorganism in acute septic arthritis of native and prosthetic joints is vital to increase the chances of successful treatment. The aim of this study was to independently assess the diagnostic accuracy of the multiplex BIOFIRE® Joint Infection (JI) Panel (investigational use only) in synovial fluid for rapid diagnosis. Method. Synovial fluid samples were prospectively collected at the University Medical Center Groningen from patients who had a clinical suspicion of a native septic arthritis, early acute (post-operative, within 3 months after arthroplasty) periprosthetic joint infection (PJI) or late acute (hematogenous) PJI. JI Panel results were compared to culture-based methods as reference standard. Results. A total of 45 samples were analyzed. The BIOFIRE JI Panel showed a high specificity (100%, 95% CI 73 – 100) and positive predictive value (100%, 95% CI 79 – 100) in all patient categories. Sensitivity and negative predictive value were 83% (95% CI 36 – 99) and 88% (95% CI 47 – 99) respectively for patients with a clinical suspicion of native septic arthritis (n=12), 77% (95% CI: 46 – 94) and 63% (95% CI: 26 – 90) for patients with a clinical suspicion of a late acute PJI (n=14), and 27% (95% CI 7 – 61) and 27% (95% CI: 7 – 61) for patients with a clinical suspicion of an early acute PJI (n=19). Conclusions. The results of this pilot study indicate a clear clinical benefit of the BIOFIRE JI Panel in patients with a suspected native septic arthritis and late acute (hematogenous) PJI, but a low clinical benefit in patients with an early acute (post-operative) PJI due to the absence of low-grade microorganisms in the panel

Aim. The diagnosis of septic arthritis mostly relies on clinical examination, several blood parameters including white blood cell count, C-reactive protein, sedimentation, and the analysis of the joint aspiration. However, the diagnosis can be difficult when the symptoms are vague and the information obtained from laboratory might be insufficient for definitive diagnosis. This study aimed to evaluate several ratios obtained from routine blood tests for a possible use in the diagnosis of septic arthritis. Method. The adult patients who were operated in our clinic due to septic arthritis between 2014–2020 were identified and retrospectively evaluated. The patients with any blood disorders or missing file information were excluded. A total of 36 patients were found to be eligible for inclusion. The control group included 40 patients without any sign of infection who underwent total knee arthroplasty due to knee osteoarthritis. Preoperative blood tests of each patients were examined. In addition to CRP and sedimentation values, neutrophil-lymphocyte, monocyte-lymphocyte, platelet-lymphocyte, and platelet count-mean platelet volume were calculated and receiving operating characteristics (ROC) curve analysis was made to determine the sensitivity, specificity and area under curve (AUC) values of these parameters. Results. The distribution of affected joint in septic arthritis group was as follow; 22 knees, 6 hips, 4 shoulders, 2 elbows, 1 wrist and 1 ankle. The cultures of joint aspiration yielded positive result in 19 patients while the cultures were negative in 17 patients. All of the analyzed parameters were significantly different between the groups (p<0.001). ROC curve analysis results are given in detail, in Table 1 and Figure 1. The AUC value was 97.3 when only CRP and sedimentation values were used but increased to 98.6 when neutrophile/ lymphocyte ratio was added and increased to 100 when all analyzed parameters were included. Conclusions. The analyzed parameters were found to increase the overall sensitivity and specificity when used together with acute phase reactants. However, when evaluated separately, CRP and sedimentation were still found as the most valuable parameters in the diagnosis of septic arthritis. In the diagnosis of septic arthritis, 35 mm/hr cut-off value for sedimentation and 10 mg/L cut-off value for CRP were found more sensitive and specific compared to standard laboratory cut-off values of 20 mm/hr and 5 mg/L. For any tables or figures, please contact the authors directly

Aims. The aim of this study was to determine the consensus best practice approach for the investigation and management of children (aged 0 to 15 years) in the UK with musculoskeletal infection (including septic arthritis, osteomyelitis, pyomyositis, tenosynovitis, fasciitis, and discitis). This consensus can then be used to ensure consistent, safe care for children in UK hospitals and those elsewhere with similar healthcare systems. Methods. A Delphi approach was used to determine consensus in three core aspects of care: 1) assessment, investigation, and diagnosis; 2) treatment; and 3) service, pathways, and networks. A steering group of paediatric orthopaedic surgeons created statements which were then evaluated through a two-round Delphi survey sent to all members of the British Society for Children’s Orthopaedic Surgery (BSCOS). Statements were only included (‘consensus in’) in the final agreed consensus if at least 75% of respondents scored the statement as critical for inclusion. Statements were discarded (‘consensus out’) if at least 75% of respondents scored them as not important for inclusion. Reporting these results followed the Appraisal Guidelines for Research and Evaluation. Results. A total of 133 children’s orthopaedic surgeons completed the first survey, and 109 the second. Out of 43 proposed statements included in the initial Delphi, 32 reached ‘consensus in’, 0 ‘consensus out’, and 11 ‘no consensus’. These 11 statements were then reworded, amalgamated, or deleted before the second Delphi round of eight statements. All eight were accepted as ‘consensus in’, resulting in a total of 40 approved statements. Conclusion. In the many aspects of medicine where relevant evidence is not available for clinicians to base their practice, a Delphi consensus can provide a strong body of opinion that acts as a benchmark for good quality clinical care. We would recommend clinicians managing children with musculoskeletal infection follow the guidance in the consensus statements in this article, to ensure care in all medical settings is consistent and safe. Cite this article: Bone Joint J 2023;105-B(7):815–820

Background. Septic arthritis diagnostic is an emergency which implies a treatment with antibiotics and hospitalization. The diagnosis is based on the cytobacteriological examination of the synovial fluid (SF), but direct bacteriological examination is insensitive, and the result of the culture is obtained only after several days. Therefore, there is still a need for a rapid, simple and reliable method for the positive diagnosis of septic arthritis. Such method must allow avoiding both unrecognized septic arthritis leading to major functional consequences, and overdiagnosis that will induce unnecessary expensive hospitalization and unjustified treatment. Mid-infrared (MIR) spectroscopy, that gives a metabolic profiling of biological fluids, has been proposed for early and fast diagnosis. Objectives. To confirm the MIR spectroscopy to discriminate SF samples from patients with septic arthritis from other causes of joint effusion. Methods. Synovial fluids from 402 patients referred for suspected arthropathies were prospectively collected in six hospitals and stored at °80°C. The infrared absorption spectrum was acquired for each of the frozen samples using a chalcogenide fiber biosensor. The most informative spectral variables were selected and then used to develop an algorithm. Then, the algorithm has been validated on independent synovial fluids collected straight after arthrocentesis from 86 patients. Results. The calibration (n=402) and validation (n=86) cohorts consists of synovial fluid samples from patients exhibiting various etiologies. These samples (n=488), by using SF bacteriological analysis and culture and 16S PCR analysis were classified as septic arthritis (n=43) or non-septic arthritis (n=443). On the calibration cohort, the performances of the algorithm show a sensitivity of 90%, a specificity of 90%, a NPV of 99% and a PPV of 41%, the area under the ROC curve (AUROC) was 0.95. On the validation cohort, the performances of the algorithm show a sensitivity of 92%, a specificity of 81%, a NPV of 98% and a PPV of 46%, the area under the ROC curve (AUROC) was 0.90. Conclusions. This study confirms the diagnostic performances of MIR spectroscopy for the discrimination between septic and non-septic synovial fluids. The high negative predictive value and the very short time (within ten minutes) required to obtain the result makes it possible to quickly rule out an infection diagnosis

Objectives. Staphylococcus aureus (S. aureus) is the most commonly implicated organism in septic arthritis, a condition that may be highly destructive to articular cartilage. Previous studies investigating laboratory and clinical strains of S. aureus have demonstrated that potent toxins induced significant chondrocyte death, although the precise toxin or toxins that were involved was unknown. In this study, we used isogenic S. aureus mutants to assess the influence of alpha (Hla)-, beta (Hlb)-, and gamma (Hlg)-haemolysins, toxins considered important for the destruction of host tissue, on in situ bovine chondrocyte viability. Methods. Bovine cartilage explants were cultured with isogenic S. aureus mutants and/or their culture supernatants. Chondrocyte viability was then assessed within defined regions of interest in the axial and coronal plane following live- and dead-cell imaging using the fluorescent probes 5-chloromethylfluorescein diacetate and propidium iodide, respectively, and confocal laser-scanning microscopy. Results. Hla-producing mutants caused substantial chondrocyte death compared with the toxin-deficient control (Hla-Hlb-Hlg-), whilst mutants producing Hlb and Hlg in the absence of Hla induced minimal chondrocyte death. Coronal studies established that Hla-induced chondrocyte death started in the superficial zone of cartilage and spread to deeper layers, whereas Hlb and Hlg toxins were without significant effect. Conclusion. This study identified Hla as a highly potent S. aureus toxin that caused rapid chondrocyte death in bovine cartilage, with other toxins or metabolic products produced by the bacteria playing a minor role. The identification of Hla in mediating chondrocyte death may assist in the development of therapeutic strategies aimed at reducing the extent of cartilage damage during and after an episode of septic arthritis. Cite this article: I. D. M. Smith, K. M. Milto, C. J. Doherty, S. G. B. Amyes, A. H. R. W. Simpson, A. C. Hall. A potential key role for alpha-haemolysin of Staphylococcus aureus in mediating chondrocyte death in septic arthritis. Bone Joint Res 2018;7:457–467. DOI: 10.1302/2046-3758.77.BJR-2017-0165.R1

C-reactive protein (CRP) level is used at our tertiary paediatric hospital in the diagnosis, management, and discharge evaluation of paediatric septic arthritis patients. The purpose of this study was to evaluate the efficacy of a discharge criterion of CRP less than 2 mg/dL for patients with septic arthritis in preventing reoperation and readmission. We also aimed to identify other risk factors of treatment failure. Patients diagnosed with septic arthritis between January 1, 2007 and December 31, 2017 were reviewed retrospectively. The diagnosis of septic arthritis was made based on clinical presentation, laboratory results and the finding of purulent material on joint aspiration or the isolation of a bacterial pathogen from joint fluid or tissue. Bivariate tests of associations between patient or infection factors and readmission and reoperation were performed. Quantitative variables were analyzed using Mann-Whitney tests and categorical variables were analyzed using Chi-square tests. One hundred eighty-three children were included in the study. Seven (3.8%) were readmitted after hospital discharge for further management, including additional advanced imaging, and IV antibiotics. Six (85.7%) of the readmitted patients underwent reoperation. Mean CRP values on presentation were similar between the two groups: 8.26 mg/dL (± 7.87) in the single-admission group and 7.94 mg/dL (± 11.26) in the readmission group (p = 0.430). Mean CRP on discharge for single-admission patients was 1.71 mg/dL (± 1.07), while it was 1.96 mg/dL (± 1.19) for the readmission group (p = 0.664), with a range of < 0 .8 to 6.5 mg/dL and a median of 1.5 mg/dL for the two groups combined. A total of 48 children (25.9%) had CRP values greater than the recommended 2 mg/dL at discharge, though only three of these patients (6.2%) were later readmitted. The only common variable in the readmitted children was either a negative culture result at time of discharge or atypical causative bacteria. CRP values are useful in monitoring treatment efficacy but not as reliable as a discharge criterion to prevent readmission or reoperation in children with septic arthritis. We recommend determining discharge readiness on the basis of clinical improvement and downtrending CRP values. There was a higher risk of readmission in children with an atypical causative bacteria and when culture results were negative at discharge. Close monitoring of these patients after discharge is suggested to identify signs of persistent infection

Septic arthritis is a medical emergency that can lead to significant morbidity and mortality arising from irreversible joint destruction and overwhelming sepsis. The purpose of this prospective study is to present epidemiological, clinical and laboratory findings in adult patients with septic arthritis. Adult patients treated for septic arthritis at the Department of Infectious Diseases, University Medical Centre Ljubljana, Slovenia, from January 2012 to December 2014, qualified for the present report. The following data were analyzed: age, sex, underlying diseases, previous joint procedure, microbiological diagnostic examinations, causative agents, complications and therapy. During the study period of three years 94 episodes of septic arthritis were diagnosed. There were 49 (52.1%) females and 45 (47.9%) males, aged 64.5 (18 to 97) years. At the first visit elevated concentration of C-reactive protein was found in 93 (98.9%) patients. The most common affected joint was knee (48.9%), followed by shoulder (20.2%), wrist (12.8%), ankle (7.4%) and others. In 8 (8.5%) patients more than one joint was affected. Risk factors were found in 63 (67%) of study patients. The underlying joint disease (e.g. osteoarthritis, rheumatoid arthritis, gout) was found in 50.8% patients, following by malignancy and immunosuppressive therapy in 28.6%, diabetes mellitus in 14.9%, recent trauma in 12.8%, and prior joint procedure in 9.6% patients. In 65/94 (69.1%) patients the causative pathogen was demonstrated by blood culture in 35.6%, by synovial fluid culture in 48.8%, and by both methods in 13.8% patients. In patients with proven aetiology Staphylococcus aureus was the most frequent (44.6%) isolated pathogen (only one methicillin resistant), followed by gram-negative bacteria in 30.8%, and Streptococcus spp. in 23.1% patients. In 4/65 (6.2%) patients more than one pathogen was isolated. The patients were treated with antibiotics according to isolated pathogen. In 17 (70.8%) out of 24 patients with complications synovectomia was performed, and adjacent osteomyelitis was found in 9 (37.5%) patients. Our results show that the foremost risk factor in adult patients with septic arthritis is pre-existing joint disease, knee is the principal target of infection, and the most common isolated pathogen is S. aureus. It was established that prompt recognition, early appropriate antimicrobial and surgical treatment in these patients are critical to ensuring a good prognosis

Acute septic arthritis of the knee may be a challenging diagnosis in the emergency department and must always be excluded in any patient with knee pain and local or systemic signs of infection. Arthrocentesis of the suspected knee is mandatory, since the analysis of the synovial fluid gives useful information like the white blood cell count (WBC)/mm3 or the polymorphonuclear cell percentage (PMP). These parameters will help the clinician to make the decision to drain the joint in the operation room, without having to wait for the culture or Gram stain, which may take several days to be available. The classical cutoff of 50,000 WBC/mm3 with more than 90% of PMP may fail to include all the septic arthritis of the knee, since significant variation have been described in recent years. The aim of this study was to evaluate the accuracy of WBC/mm3 and PMP in the synovial fluid in the diagnosis of acute septic arthritis of the knee. We reviewed the clinical data of patients diagnosed with acute septic arthritis of the knee admitted in our center between January 2010 and December 2014, specifically the WBC/mm3 and the PMP of the synovial joint fluid. The criteria for diagnosis of an acute septic arthritis of the knee was report of purulent material when arhtrotomy or arthroscopy was performed or a positive culture of the joint fluid. The statistical evaluation of the results was performed using Student's t-test. 48 patients matched the inclusion criteria. The mean WBC/mm3 was 44.333 (14.610–182.640) and the mean PMP was 91,89% (86,4%–98,1%). 28 patients (58,33%) had a WBC/mm3 below 50.000 and 44 patients (91,67%) had a PMP above 90%, both with no statistical significance. Knee arthrocentesis is mandatory in every patient suspected to have an acute knee pyoarthrosis, since the joint fluid analysis may show several abnormal findings. Our results show that a considerable number of patients may show a relatively low WBC/mm3 in the joint fluid in the presence of a knee pyoarthrosis. The PMP may be a better criteria, but again failed to achieve statistical significance, probably because of the low number of patients. The synovial fluid analysis alone is probably misleading in the diagnosis of an acute septic arthritis of the knee if the clinician is guided by the classical guidelines. The physical examination, medical history, laboratory and imagiologic tests are all key elements in this challenging diagnosis

Aim: An epidemiological analysis of spontaneous community acquired septic arthritis cases in an elderly population at a university teaching hospital. Method: We studied confirmed cases of spontaneous septic arthritis in the over 65 population. Patients with prosthetic joint infections were excluded from the study. We analysed data relating to initial presenting complaint and clinical examination, haematological and microbio-logical tests along with ultimate patient outcome. Results: There were 7 confirmed cases of spontaneous septic arthritis in over 65 population in the last 6 months (2 hips, 5 knees). The mean age was 72.14 (range 65–82) with a mean length of stay of 49 days. Those with septic arthritis of the knee presented with swelling, pain and immobility. Hip cases presented with pain and immobility. All patients were systemically well at time of presentation, with no other foci of infection detected after septic screening. All patients had aspirate and arthroscopic/arthrotomy confirmed infection. Staphylococcus Aureus was isolated from 6 joint aspirations and Pseaudomonas Auruginosa from one patient. Complications of treatment included acute renal failure, cardio/respiratory failure, disseminated infection and death (1 case). Conclusion: Septic arthritis must be considered as a differential diagnosis in all patients with joint pain, swelling and immobility. This diagnosis is not confined to the paediatric population. A backround of degenerative disease and the occult presentation in the elderly may delay diagnosis. Sepsis must be considered in the elderly with joint pathology, with treatment initiated in a prompt and aggressive manner to prevent the sequelae that ensues

Aim. Septic arthritis of the hip is a rare entity among the adult population, but with a potential severe repercussion. The most accepted treatment is the hip debridement, even though a notorious proportion of the cases need further hip replacement owing to the cartilage destruction. The aim of this study is to analyse all our cases of septic arthritis of the hip treated with a 2-stage strategy using an antibiotic-loaded cement spacer. Method. We present a retrospective review of all our cases of septic arthritis of the hip diagnosed between 2004 and 2016 that were treated with an antibiotic-loaded cement spacer. We analysed age, gender, comorbidities, aetiology, duration of symptoms, C-reactive protein values, erythrocyte sedimentation rate, initial treatment, cultures, definitive treatment and evolution. Results. A total of 14 cases were included with a mean age of 47 years: 8 men and 6 women. The aetiology of the arthritis was: haematogenous in 8 cases, after osteosynthesis in 5 cases and after arthroscopy in 1 case. An initial debridement was performed in 6 cases whereas the spacer was directly implanted in 8 cases. The cultures were positive for: Staphylococcus aureus (4 cases), Candida albicans (2 cases), Staphylococcus epidermidis (1 case), Pseudomonas aeruginosa (1 case), Enterococcus faecium (1 case), Serratia marcescens (1 case), Streptococcus dysgalactiae (1 case), Salmonella spp (1 case) and negative in 2 cases. The evolution was: total hip arthroplasty in 10 cases, spacer preserved in 2 cases, pending of hip replacement in 1 case and exitus in 1 case. All cases presented negative cultures at the moment of implantation of the definitive prosthesis. Conclusions. A 2-stage strategy using an antibiotic-loaded cement spacer prior to the definitive hip prosthesis is a good treatment for the septic arthritis of the hip in cases with important cartilage destruction

Aim. Successful management of native Joint septic arthritis (SA) hinges on the timely initiation of appropriate antibiotic therapy coupled with thorough joint debridement. Since 2018 we have implemented a protocol for empirical antibiotic in patients with suspected SA recommending amoxicillin/clavulanate (and cotrimoxazole in cases of beta-lactams allergy) based on local flora. Nevertheless we have recently found that institutional compliance to the protocol is only about 50% and many physicians are still choosing alternative wider spectrum regimens. The aim of this study is to assess whether current clinical and epidemiological characteristics of patients treated for this condition justify an update or whether previous recommendations are still valid. Method. All adult patients admitted to our institution with suspected SA between 2018-2022 were retrospectively reviewed. Data was collected from electronic medical records and then compared to similar data previously collected concerning the 2009-2017 period (that served as a basis for the aforementioned protocol). Results. A summary of available data from both time periods can be found in table 1. Overall, among the 35 patients with positive microbiology treated between 2018-2022, amoxicillin/clavulanate is appropriate for 30 (86%) of isolates (vs 88% in historic control). Analysing the whole cohort, we found that previous contact with healthcare services (hospital admission or prolonged ER stay) (p=0.0044) and antibiotic treatment for any infection (p= 0.0213) in the previous six months correlate with resistance to amoxicillin/clavulanate. In these patients, the proposed alternative cotrimoxazole is effective in 77% of cases. Conclusions. The institutional guideline for empirical antibiotic therapy in native joint SA remains adequate and there seems to be no justification to deviate from protocol except in cases of patients admitted to the hospital or antibiotic treatment in the previous six months. In these cases methicillin-resistance coverage is probably appropriate. Pseudomonal coverage is seldom required in SA. For any tables or figures, please contact the authors directly