Joint Prosthesis Infection Research Articles

Cutibacterium acnes biofilm formation is influenced by bone microenvironment, implant surfaces and bacterial internalization

BackgroundThe bacterial persistence, responsible for therapeutic failures, can arise from the biofilm formation, which possesses a high tolerance to antibiotics. This threat often occurs when a bone and joint infection is diagnosed after a prosthesis implantation. Understanding the biofilm mechanism is pivotal to enhance prosthesis joint infection (PJI) treatment and prevention. However, little is known on the characteristics of Cutibacterium acnes biofilm formation, whereas this species is frequently involved in prosthesis infections.MethodsIn this study, we compared the biofilm formation of C. acnes PJI-related strains and non-PJI-related strains on plastic support and textured titanium alloy by (i) counting adherent and viable bacteria, (ii) confocal scanning electronic microscopy observations after biofilm matrix labeling and (iii) RT-qPCR experiments.ResultsWe highlighted material- and strain-dependent modifications of C. acnes biofilm. Non-PJI-related strains formed aggregates on both types of support but with different matrix compositions. While the proportion of polysaccharides signal was higher on plastic, the proportions of polysaccharides and proteins signals were more similar on titanium. The changes in biofilm composition for PJI-related strains was less noticeable. For all tested strains, biofilm formation-related genes were more expressed in biofilm formed on plastic that one formed on titanium. Moreover, the impact of C. acnes internalization in osteoblasts prior to biofilm development was also investigated. After internalization, one of the non-PJI-related strains biofilm characteristics were affected: (i) a lower quantity of adhered bacteria (80.3-fold decrease), (ii) an increase of polysaccharides signal in biofilm and (iii) an activation of biofilm gene expressions on textured titanium disk.ConclusionTaken together, these results evidenced the versatility of C. acnes biofilm, depending on the support used, the bone environment and the strain.

Impact of antibiotic prophylaxis in second-stage surgery in joint prosthesis infection treated with two-stage exchange. A multicenter case-control study.

After two-stage exchange due to prosthetic joint infection (PJI), the new prosthesis carries a high risk of reinfection (RePJI). There isn`t solid evidence regarding the antibiotic prophylaxis in 2nd-stage surgery. The objective of this study is to describe what antibiotic prophylaxis is used in this surgery and evaluate its impact on the risk of developing RePJI. Retrospective multicenter case-control study in Spanish hospitals. The study included cases of PJI treated with two-stage exchange and subsequently developed a new infection. For each case, two controls were included, matched by prosthesis location, center, and year of surgery. The prophylaxis regimens were grouped based on their antibacterial spectrum, and we calculated the association between the type of regimen and the development of RePJI using conditional logistic regression, adjusted for possible confounding factors. We included 90 cases from 12 centers, which were compared with 172 controls. The most frequent causative microorganism was Staphylococcus epidermidis with 34 cases (37.8%). Staphylococci were responsible for 50 cases (55.6%), 32 of them (64%) methicillin-resistant. Gram-negative bacilli were involved in 30 cases (33.3%), the most common Pseudomonas aeruginosa. In total, 83 different antibiotic prophylaxis regimens were used in 2nd-stage surgery, the most frequent a single preoperative dose of cefazolin (48 occasions; 18.3%); however, it was most common a combination of a glycopeptide and a beta-lactam with activity against Pseudomonas spp (99 cases, 25.2%). In the adjusted analysis, regimens that included antibiotics with activity against methicillin-resistant staphylococci AND Pseudomonas spp were associated with a significantly lower risk of RePJI (adjusted OR = 0.24; 95% IC: 0.09-0.65). The lack of standardization in 2nd-satge surgery prophylaxis explains the wide diversity of regimens used in this procedure. The results suggest that antibiotic prophylaxis in this surgery should include an antibiotic with activity against methicillin-resistant staphylococci and Pseudomonas.

Perioperative antibiotic prophylaxis in skin surgery - Position paper of the Antibiotic Stewardship working group of the German Society for Dermatologic Surgery (DGDC), Part 2: Special indications and situations.

In addition to prevention of surgical site infections after skin surgery, perioperative antibiotic prophylaxis (PAP) aims to prevent the occurrence of other postoperative infectious complications, especially bacterial endocarditis and hematogenous joint prosthesis infections. This article discusses specific indications for the use of PAP. For example, patients who have undergone any type of heart valve replacement, including transcatheter valve replacement or use of prosthetic material to correct the heart valve, or patients who have experienced bacterial endocarditis, require PAP during skin surgery on mucosal membranes or ulcerated tumors. The use of PAP in special situations such as secondary wound healing, septic dermatosurgery or ulcer surgery is also presented and discussed in detail in this paper based on the current scientific literature. This paper represents the second part of the position paper of the Antibiotic Stewardship Working Group of the German Society for Dermatologic Surgery (DGDC) and summarizes evidence-based recommendations for the administration of PAP during skin surgery for special indications and situations. This is particularly important because, as detailed in Part 1 of this position paper, PAP can and usually should be avoided in skin surgery.

Effect of supplemental testosterone use on shoulder arthroplasty infection rates

BackgroundSupplemental testosterone use among patients undergoing shoulder arthroplasty can increase the Cutibacterium acnes load on the skin. Although higher C acnes loads on the skin are associated with higher amounts of bacteria in deep tissues, it is unknown whether preoperative testosterone use increases the risk of shoulder prosthetic joint infection. Therefore, the purpose of this study was to determine if there is a temporal relationship between testosterone use and the risk of prosthetic joint infection after shoulder arthroplasty. MethodsThe PearlDiver database was queried to identify a cohort of patients who underwent shoulder arthroplasty (hemiarthroplasty, anatomic or reverse total shoulder arthroplasty) with a minimum 2-year follow-up. Current Procedural Terminology and International Classification of Diseases codes were used to compare the demographics and comorbidities of patients with (n = 2285) and without testosterone use (n = 41,712). Patients with testosterone use were further stratified by the duration between last testosterone use and surgery. Prosthetic joint infection rates were compared between those with and without testosterone use. ResultsThe overall prevalence of testosterone use was 3.4%. Patients who used testosterone within 6 months prior to shoulder arthroplasty had a significantly higher rate of prosthetic joint infection at 3.4% compared to those without use at 2.4% [odds ratio (OR) = 1.44 (95% confidence interval (CI): 1.03-2.01), P = .042]. However, patients who used testosterone between 6 and 12 months before surgery did not have a significantly higher rate of infection. On multivariate analysis, only younger age [OR = 0.98 (95% CI: 0.97-0.99), P < .001] and diabetes [OR = 1.26 (95% CI: 1.10-1.44), P < .001] were independent risk factors for the development of an infection. ConclusionTestosterone use within 6 months of shoulder arthroplasty may be associated with higher rates of prosthesis joint infection. However, patients who were taking testosterone but stopped before surgery did not have a higher rate of infection compared to those who never used the medication. Surgeons should actively screen patients for testosterone use. A referral to the patient’s endocrinologist to discuss the risks and benefits of testosterone cessation prior to shoulder arthroplasty may also be warranted.

Knowledge and attitudes of orthopedic surgeons regarding prosthesis joint infection.

Periprosthetic joint infection (PJI) is a critical complication after joint arthroplasty and is accompanied by increasing rates of morbidity and mortality. Several studies have aimed at preventing PJI. To research the knowledge level and attitudes of orthopedic surgeons, who play a key role in both preventing and managing PJI. We conducted a web-based survey to evaluate orthopedic surgeons' knowledge level and attitudes regarding PJI. The Likert scale survey utilized consisted of 30 questions which were prepared based on the "Proceedings of the International Consensus on Periprosthetic Joint Infection". A total of 264 surgeons participated in the survey. Their average age was 44.8, and 173 participants (65.5%) had more than 10 years of experience. No statistically significant relationship was found between the PJI knowledge of the surgeons and their years of experience. However, participants who worked in training and research hospitals demonstrated higher levels of knowledge than the ones in the state hospitals. It was also noticed that surgeons' knowledge concerning the duration of antibiotic therapy and urinary infections was not consistent with their attitudes. Even though orthopedic surgeons have adequate knowledge about preventing and managing PJI, their attitudes might contradict their knowledge. Future studies are required to examine the causes and solutions of the contradictions between orthopedic surgeons' knowledge and attitudes.

A Meta-Analysis of Polymerase Chain Reaction for Prosthetic Joint Infection Diagnosis.

One of the most dangerous side effects of joint replacement for the hip, knee, shoulder, and elbow is prosthesis joint infection (PJI). Polymerase chain reaction (PCR) has been considered a promising method for PJI diagnosis due to its short diagnostic time and high sensitivity. Although several PCR methods such as multiplex PCR and broad-range PCR are useful diagnostic methods for detecting microorganisms causing PJI, values of different PCR methods for the diagnosis of PJI remain unclear. Thus, the objective of this study was to perform a meta-analysis of different PCR methods in the diagnosis of PJI to determine their diagnostic characteristics including sensitivity and specificity. The following data were extracted: PCR method, number of patients, sample site and type, diagnosis standard, true positive, false positive, false negative, and true negative. Pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were calculated. Meta-regression analysis was conducted to assess heterogeneity. Subgroup analysis was also performed to assess effects of several variables on meta-analysis results. The current study showed that pooled sensitivity and pooled specificity were 0.70 (95% CI: 0.67 - 0.73) and 0.94 (95% CI: 0.92 - 0.95), respectively. Results of subgroup analysis indicated that sequencing method showed the lowest sensitivity (0.63, 95% CI: 0.59 - 0.67). However, after excluding studies using tissue samples directly, sequencing method showed higher sensitivity (0.83, 95% CI: 0.73 - 0.90) than other PCR methods (0.74, 95% CI: 0.69 - 0.78). The main significance of this study was that we attempted to classify accuracies of several PCR methods and found that sequencing with a reliable sampling method could be used as an early screening strategy for PJI. Further comparisons for PCR technologies are needed to evaluate their cost effectiveness and diagnostic procedures, not just diagnostic values, to discover the optimal one for PJI diagnosis.

Differences in Efficacy between Short- and Long-Course Antibiotic Agents for Joint Prosthesis Infection: A Systematic Review and Meta-Analysis.

Background: To evaluate systematically the failure rate of short versus long courses of antibiotic agents for prosthetic joint infections (PJIs). Methods: PubMed, Embase, and Cochrane Library databases were searched for controlled studies of short- and long-course antibiotic agents for joint prosthesis infections, all from the time of database creation to April 2022. Literature search, quality evaluation, and data extraction were performed independently by two researchers, and the primary outcome was the rate of surgical failure after antibiotic treatment. Stata 11.0 software was then applied for meta-analysis. Publication bias was assessed using Begg test. Heterogeneity was assessed using the I2 test, and fixed or random effects models were used accordingly. Meta-regression was used to determine the causes of heterogeneity. Results: A total of 14 articles involving 1,971 participants met the inclusion criteria, including 12 observational studies and two randomized controlled trials. Meta-analysis showed no difference between short and long courses of antibiotic agents (relative risk, 1.08; 95% confidence interval [CI], 0.89-1.32). The results of the subgroup analysis showed no differences between the failure rates of patients with PJI treated with short and long courses of antibiotic agents in studies with different study areas, different treatment modalities, and different locations of the artificial joints. Conclusions: Patients with PJIs may not require long-term or lifelong antibiotic agents after surgical treatment, and short-term (four to six weeks) antibiotic therapy is usually safe.

Prosthetic joint infection of the hip and knee due to Mycobacterium species: A systematic review.

BACKGROUND Mycobacterium species (Mycobacterium sp) is an emerging cause of hip and knee prosthetic joint infection (PJI), and different species of this organism may be responsible for the same.AIMTo evaluate the profile of hip and knee Mycobacterium PJI cases as published in the past 30 years.METHODSA literature search was performed in PubMed using the MeSH terms “Prosthesis joint infection” AND “Mycobacterium” for studies with publication dates from January 1, 1990, to May 30, 2021. To avoid missing any study, another search was performed with the terms “Arthroplasty infection” AND “Mycobacterium” in the same period as the previous search. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses chart was used to evaluate the included studies for further review. In total, 51 studies were included for further evaluation of the cases, type of pathogen, and treatment of PJI caused by Mycobacterium sp.RESULTSSeventeen identified Mycobacterium sp were reportedly responsible for hip/knee PJI in 115 hip/knee PJI cases, whereas in two cases there was no mention of any specific Mycobacterium sp. Mycobacterium tuberculosis (M. tuberculosis) was detected in 50/115 (43.3%) of the cases. Nontuberculous mycobacteria (NTM) included M. fortuitum (26/115, 22.6%), M. abscessus (10/115, 8.6%), M. chelonae (8/115, 6.9%), and M. bovis (8/115, 6.9%). Majority of the cases (82/114, 71.9%) had an onset of infection > 3 mo after the index surgery, while in 24.6% (28/114) the disease had an onset in ≤ 3 mo. Incidental intraoperative PJI diagnosis was made in 4 cases (3.5%). Overall, prosthesis removal was needed in 77.8% (84/108) of the cases to treat the infection. Overall infection rate was controlled in 88/102 (86.3%) patients with Mycobacterium PJI. Persistent infection occurred in 10/108 (9.8%) patients, while 4/108 (3.9%) patients died due to the infection.CONCLUSIONAt least 17 Mycobacterium sp can be responsible for hip/knee PJI. Although M. tuberculosis is the most common causal pathogen, NTM should be considered as an emerging cause of hip/knee PJI.

Early outcomes of limb salvage surgery with mega-prosthesis

Objective: To determine the early outcomes of limb salvage surgery with mega prosthesis. Methods: This retrospective study was conducted at Shaukat Khanum Memorial Cancer Hospital and Research Centre (SKMCH&amp;RC) from 1st January 2017 till 31st January 2020. Data like demographics, histopathology, functional and survival outcomes were retrieved from the Hospital Information System. Musculoskeletal Tumor Society (MSTS) score was used to evaluate the functional outcomes after the surgery. For survival analyses, Kaplan-Meier curve was applied. Prosthesis joint infection, amputation rate, metastasis, mortality rate, and recurrence were also recorded. Results: This study included 43 patients who underwent limb salvage surgery with endoprosthesis reconstruction at SKMCH&amp;RC. The mean age at the time of diagnosis was (26.5±15.8) years. Patients with distal femoral replacement had the highest MSTS scores (81.45±9.70) while those with proximal humerus replacement has the lowest MSTS scores (56.8±11.2). There was a strong association between site of tumor and MSTS (F=3.30, P=0.017). We also found a correlation between surgical site infection and MSTS scores (r=0.484, P=0.001). Patients with recurrence also had significantly lower MSTS scores (P&lt;0.05). The cumulative survival rate at the end of two-year follow-up was (71.4±17.1)% in proximal femur tumor patients, (88.0±7.8)% in distal femur tumor patients, and (50.0±3.5)% in proximal humerus tumor patients. Besides, patients with Ewing sarcoma had the highest survival rate (97.5±11.0)% while patients with chondrosarcoma had the lowest survival rate (77.8±13.9)%. Conclusions: Limb salvage surgery with mega-prosthesis can be performed with satisfactory functional and survival outcomes, but further studies are needed to compare it with other limb salvage methods. This study can be used as a reference for future studies.

Preoperative Correction of Anemia to Allow a 3000 ml Blood Loss Without Transfusion in a Jehovah’s Witness Presenting for Explantation of an Infected Hip Joint Prosthesis: A Case Report

A 70-year-old Jehovah's Witness was treated with iron carboxymaltose intravenously, recombinant human erythropoietin alpha subcutaneously, and vitamin B12 and folate orally for 9 weeks to raise hemoglobin (Hb) from 10.8 to 17.0 g/dL before explantation of an infected hip joint prosthesis. The target Hb was calculated from the following formula: Hbtarget = Hbfinal/(1 - ABL/EBV), where Hbtarget= Hb to achieve before surgery, Hbfinal = lowest Hb patient could tolerate taking into consideration his comorbidities (7 g/dL), ABL = volume of blood the surgeon estimated the patient would lose intra- and postoperatively (3000 mL), and EBV = estimated blood volume (75 mL/kg for an adult man). Spinal anesthesia was provided with a single shot hyperbaric bupivacaine and fentanyl. Acute hypervolemic hemodilution was achieved with lactated Ringer's solution and hydroxyethyl starch. To further minimize blood loss, controlled hypotension to a mean blood pressure of 55 mm Hg was achieved with a propofol infusion and tranexamic acid was administered. Surgical blood loss was estimated to be 2500 mL. Hb at the end of surgery was 13.3 g/dL; on postoperative day 5, 11.7 g/L. No blood products were utilized.

Research progress on polymerase chain reaction diagnosis technique for joint prosthesis infection

Although the incidence of prosthesis joint infection(PJI) is low, it is one of more serious complications recognized by joint surgery because of the difficulty in diagnosis and treatment, so it is very important to diagnose PJI in time. Currently, clinical diagnostic techniques for PJI are immature, and each technique has certain limitations in terms of sensitivity or specificity of diagnosis. In general, the diagnosis of PJI relies mainly on clinical symptoms, laboratory tests and imaging examinations. The detection of pathogenic microorganisms is the basis of laboratory diagnosis and clinical treatment. The results of microbial susceptibility testing are also the main basis for the clinical application of sensitive antibiotics to treat PJI. However, the current positive rate of PJI pathogen culture is not high. In comparison, polymerase chain reaction(PCR) technology does not depend on the premise that unknown microorganisms can be cultured in vitro, and it is rapid and highly sensitive. Therefore, the use of genetic technology, especially PCR technology to diagnose PJI has become one of the current research hot spots. In order to understand the research and development of PCR diagnostic techniques for joint prosthesis infection in recent years, in this paper, the research progress of genetic technology is reviewed, especially PCR technology in the diagnosis of PJI. Key words: Infection; Polymerase chain reaction; Diagnosis; Replacement

Machine Learning Analyses on Data including Essential Oil Chemical Composition and In Vitro Experimental Antibiofilm Activities against Staphylococcus Species.

Biofilm resistance to antimicrobials is a complex phenomenon, driven not only by genetic mutation induced resistance, but also by means of increased microbial cell density that supports horizontal gene transfer across cells. The prevention of biofilm formation and the treatment of existing biofilms is currently a difficult challenge; therefore, the discovery of new multi-targeted or combinatorial therapies is growing. The development of anti-biofilm agents is considered of major interest and represents a key strategy as non-biocidal molecules are highly valuable to avoid the rapid appearance of escape mutants. Among bacteria, staphylococci are predominant causes of biofilm-associated infections. Staphylococci, especially Staphylococcus aureus (S. aureus) is an extraordinarily versatile pathogen that can survive in hostile environmental conditions, colonize mucous membranes and skin, and can cause severe, non-purulent, toxin-mediated diseases or invasive pyogenic infections in humans. Staphylococcus epidermidis (S. epidermidis) has also emerged as an important opportunistic pathogen in infections associated with medical devices (such as urinary and intravascular catheters, orthopaedic implants, etc.), causing approximately from 30% to 43% of joint prosthesis infections. The scientific community is continuously looking for new agents endowed of anti-biofilm capabilities to fight S. aureus and S epidermidis infections. Interestingly, several reports indicated in vitro efficacy of non-biocidal essential oils (EOs) as promising treatment to reduce bacterial biofilm production and prevent the inducing of drug resistance. In this report were analyzed 89 EOs with the objective of investigating their ability to modulate bacterial biofilm production of different S. aureus and S. epidermidis strains. Results showed the assayed EOs to modulated the biofilm production with unpredictable results for each strain. In particular, many EOs acted mainly as biofilm inhibitors in the case of S. epidermidis strains, while for S. aureus strains, EOs induced either no effect or stimulate biofilm production. In order to elucidate the obtained experimental results, machine learning (ML) algorithms were applied to the EOs’ chemical compositions and the determined associated anti-biofilm potencies. Statistically robust ML models were developed, and their analysis in term of feature importance and partial dependence plots led to indicating those chemical components mainly responsible for biofilm production, inhibition or stimulation for each studied strain, respectively.

Destination Joint Spacers, Reinfection, and Antimicrobial Suppression

In this cohort of 51 patients managed with retained "destination spacers" after the resection of infected joint prostheses, the presence of preoperative sinus drainage was significantly associated with reinfection. Chronic antimicrobial suppression after destination-spacer retention did not significantly prevent reinfections.

Case for diagnosis. Suppurative nodule or something deeper?

The authors report the case of a 62-year-old man with a history of total left hip arthroplasty nine years previously presenting with a large infiltrated plaque on the posterior area of the left thigh with three months of evolution without systemic symptoms or elevated inflammatory markers. Computed tomography of the left lower limb revealed a 12-centimeter linear extension of the lesion to the posterior part of the left proximal femur. Prosthesis joint infection, although rare, is a surgical complication to be taken into account, even if the surgery was performed many years before.

Temporomandibular total joint prosthesis infections: a ten-year retrospective analysis

A retrospective review of 178 total temporomandibular joint replacements (TJR) performed on 106 patients at the University of Alabama at Birmingham during the years 2000–2010 was completed. Data regarding sex, past medical history, prosthesis manufacturer, microbiology, antibiotic therapy, and the need for additional procedures were obtained from the medical records of patients who developed a prosthetic joint infection following TJR. Of the 106 patients, 95 (89.6%) were female and 11 (10.4%) were male. The average age of the patients was 47 years (range 19–68 years). Sixty patients underwent bilateral TJR. The average length of follow-up was 41 months. Of the 178 TJR performed, eight joints (4.5%) developed an infection of the prosthesis, all requiring removal despite antibiotic therapy. The average time to onset of infection was 14.3 months (range 6 days to 72 months), while the average time to removal of the prosthesis was 26.9 months (range 10 weeks to 84 months). Microbiology data from the infected joints revealed colonization with coagulase-negative Staphylococcus (4/8 joints) and Propionibacterium (2/8 joints), as well as Serratia and Peptostreptococcus species. Three of the prostheses had negative cultures.

Results of combined vascular reconstruction by means of AV loops and free flap transfer in patients with soft tissue defects

Free flap transplantation to vascular reconstructions as arteriovenous (AV) loops has been established in centers as a feasible therapeutic option for defect reconstruction in the absence of proper recipient vessels, caused by oncologic resections, radiation, or trauma. We report our 10-year experience in free flap transplantation after vascular reconstruction with special emphasis on complication rate and postoperative mobility. Forty-seven patients (mean age: 60 years, range: 19-86) were included. Defect etiology was posttraumatic in 19 patients; 14 defects were due to oncological resections and seven sternal osteomyelitis; three patients presented with radiation ulcers, two with aseptic femoral head necrosis, and one with defects caused by acne inversa and hip joint prosthesis infection. Long-term follow-up was 45 months (range: 0-126). We performed arterial revascularization with 36 AV loops, eight bypass grafts, and three venous interposition grafts. Subsequent tissue transfer comprised 24 latissimus dorsi, two vastus lateralis, one gracilis, one anterior lateral thigh (ALT), 16 rectus abdominis, one radialis forearm, and two osteocutaneous vascularized fibula flaps. Complications occurred in 25/47 patients (53%). Early complications included five acute occlusions of arterial reconstructions and six major bleedings. There were six flap losses and three major amputations. Two in-hospital deaths were observed (4%). Overall survival accounted for 89.0 and 74.7% after 1 and 5 years, respectively. The 5-year survival rate in long-term follow-up is favorable, despite an initially elevated complication rate. Successful defect coverage can be achieved by this method in a high percentage of patients.

Reduction of Treatment Duration in Periprosthetic Infection with a Fast-Track Concept Is Economically Not Feasible

In the two stage revision of periprosthetic joint infection (PJI), the prosthesis-free interval may be reduced to 2-3 weeks (fast-track). This is an innovative approach with clear advantages for both the patient and health insurance stakeholders. The prosthesis-free interval with conventional two-stage PJI slow-track procedures lasts 6-12 weeks. In Germany, the patient spends this time either at home or in a geriatric hospital. This period is mainly used to manage infections. The patient is then readmitted for implantation of the revision prosthesis. This readmission then leads to additional reimbursement, as this is formally a new insurance case. Despite this double payment, the costs for the treatment of such complex diseases are not covered by the German DRG system. If hospitals are to implement the proven fast-track concept, they need to invest in a multidisciplinary medical team. This would be responsible for defining infections, selecting patients, and improving diagnosis and antimicrobial therapy and should thus improve the rates of cure of infections. However, the G-DRG reimbursement system treats the two surgeries as a single case, providing that less than 30 days lies between the two interventions; as a result, the reimbursement is inadequate for patients with the fast-track interval. We analysed the theoretical financial deficit for a hospital and describe the cost-saving potential for payers applying the fast-track interval rather than the slow-track approach in selected PJI patients, using a comprehensive and individualised treatment concept. Our analysis covered thirty-two consecutive patients with infected joint prosthesis (17 hips, 15 knee) admitted to our hospital from January 2011 to December 2012 undergoing a two-stage exchange (ICD-10-GM: T84.5). We excluded patients who underwent only one hospital admission during the analysed time frame or who were admitted to another hospital. Patients treated with joint fusion and patients who died were also excluded. A retrospective simulation of the DRG reimbursement was then performed according to the German Hospital Fees Act (§ 21 KHEntgG) for the two-stage fast-track interval concept. Due to the retrospective character, we could not analyse detailed financial differences specifically related to the fast-track treatment, such as the cost for biofilm active antimicrobial drugs and savings for outpatient care during the long interval in slow-track. We did not consider hospital investment costs for establishing an interdisciplinary medical team, and were only able to roughly describe the cost saving potential and benefits on a societal perspective. With the fast-track concept, the DRG receipts were reduced by a mean of 10 831 € per patient, which was higher for hip prostheses than for knee prostheses. Even though fast-track treatment cost 1159 € less than slow-track treatment, the hospital lost 8498 € per fast-track patient, because of the loss of the second surgery reimbursement. For each fast-track patient, the payers save one G-DRG reimbursement plus the costs for any care during the prosthesis-free interval, as occurred in the slow-track. Fast-track patients benefit from the reduced period of functional treatment, of about 10 weeks. The current G-DRG reimbursement system paradoxically rewards slow-track intervals for two-stage revisions and jeopardizes the implementation of beneficial fast-track intervals in clinical routine. Patients treated with slow-track therapy experience longer and more debilitating treatment, accompanied by greater healthcare costs for both payers and hospitals. New treatment concepts which offer better care at lower cost should attract the attention of policy makers, clinicians, and the public.

Clinical Significance and Characterization of Streptococcus tigurinus Isolates in an Adult Population.

Streptococcus tigurinus is a newly described member of the Streptococcus mitis group. Due to the difficulty in distinguishing viridans group streptococci (VGS) by phenotype, analysis of 16S rRNA sequences is necessary for the accurate identification of most species. Through a laboratory policy of analyzing all clinically significant isolates from the VGS group by16S rRNA gene sequencing, we identified 14 S. tigurinus isolates from 11 patients. The Vitek 2 system most commonly gave an excellent rating to an incorrect identification (e.g., Streptococcus mitis), as did matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) (e.g., Streptococcus oralis). S. tigurinus strains were recovered from numerous body sites, including the blood, peritoneal fluid, bone, synovial fluid, a perianal abscess, and an arm wound. Retrospective chart review indicated that most isolates were clinically significant, with bacteremia (n = 5), soft tissue infections (n = 3) osteomyelitis (n = 2), infected joint prosthesis (n = 2), and peritonitis (n = 2) being the most common, thus expanding the spectrum of disease associated with S. tigurinus.

Screening with angiographic images prior to (99m)Tc-HMPAO labelled leukocyte scintigraphy in the diagnosis of periprosthetic infection

To evaluate the impact of the angioscintigrapy of the three phase bone scan as screening method to rule out infection of the hip and knee prosthesis prior to performing the (99m)Tc-HMPAO leukocyte scintigraphy. A total of 120 (70 women, 50 men; mean age 71±11years) with clinical suspicion of hip (n=63) or knee (n=57) infection of the prosthesis and clinical suspicion of infection were evaluated prospectively. All patients underwent three-phase bone scan (angioscintigraphy, vascular and bone phase) and (99m)Tc-HMPAO-labelled white blood cell scintigraphy. Final diagnosis of infection was made by microbiological documentation or clinical follow-up for at least 12months. Eighteen out of 120 patients were diagnosed of infection of hip prosthesis (n=10) or knee prosthesis (n=8). The angioscintigraphy was positive in 15/18 infected cases and in 21/102 of the non-infected cases with a sensitivity of 83%, specificity of 79% and negative predictive value of 97%. Sensitivity and specificity of (99m)Tc-HMPAO leukocyte scintigraphy were 72% and 95%, respectively. If the leukocyte labeled scintigraphies had been used exclusively for patients with positive angioscintigraphy, this would have saved up to 70% of the (99m)Tc-HMPAO leukocyte scintigraphies performed. There were no cases of infection with positive labeled leukocyte scintigraphy and negative angioscintigraphy. Angioscintigraphy (blood flow phase of bone scan) is a useful technique for screening for hip and knee joint prosthesis infection, significantly reducing the need for (99m)Tc-HMPAO leukocyte scintigraphy without affecting the sensitivity of the technique.

Screening with angiographic images prior to 99mTc-HMPAO labelled leukocyte scintigraphy in the diagnosis of periprosthetic infection

AimTo evaluate the impact of the angioscintigrapy of the three phase bone scan as screening method to rule out infection of the hip and knee prosthesis prior to performing the 99mTc-HMPAO leukocyte scintigraphy. Material and methodsA total of 120 (70 women, 50 men; mean age 71±11years) with clinical suspicion of hip (n=63) or knee (n=57) infection of the prosthesis and clinical suspicion of infection were evaluated prospectively. All patients underwent three-phase bone scan (angioscintigraphy, vascular and bone phase) and 99mTc-HMPAO-labeled white blood cell scintigraphy. Final diagnosis of infection was made by microbiological documentation or clinical follow-up for at least 12 months. ResultsEighteen out of 120 patients were diagnosed of infection of hip prosthesis (n=10) or knee prosthesis (n=8). The angioscintigraphy was positive in 15/18 infected cases and in 21/102 of the non-infected cases with a sensitivity of 83%, specificity of 79% and negative predictive value of 97%. Sensitivity and specificity of 99mTc-HMPAO leukocyte scintigraphy were 72% and 95%, respectively. If the leukocyte labeled scintigraphies had been used exclusively for patients with positive angioscintigraphy, this would have saved up to 70% of the 99mTc-HMPAO leukocyte scintigraphies performed. There were no cases of infection with positive labeled leukocyte scintigraphy and negative angioscintigraphy. ConclusionAngioscintigraphy (blood flow phase of bone scan) is a useful technique for screening for hip and knee joint prosthesis infection, significantly reducing the need for 99mTc-HMPAO leukocyte scintigraphy without affecting the sensitivity of the technique.