Italian Guidelines for the Diagnosis and Infectious Disease Management of Osteomyelitis and Prosthetic Joint Infections in Adults

Modern Microbiological Methods to Detect Biofilm Formation in Orthopedy and Suggestions for Antibiotic Therapy, with Particular Emphasis on Prosthetic Joint Infection (PJI)

Biofilm formation is a serious problem that relatively often causes complications in orthopedic surgery. Biofilm-forming pathogens invade implanted foreign bodies and surrounding tissues. Such a condition, if not limited at the appropriate time, often requires reoperation. This can be partially prevented by selecting an appropriate prosthesis material that prevents the development of biofilm. There are many modern techniques available to detect the formed biofilm. By applying them we can identify and visualize biofilm-forming microorganisms. The most common etiological factors associated with biofilms in orthopedics are: Staphylococcus aureus, coagulase-negative Staphylococci (CoNS), and Enterococcus spp., whereas Gram-negative bacilli and Candida spp. also deserve attention. It seems crucial, for therapeutic success, to eradicate the microorganisms able to form biofilm after the implantation of endoprostheses. Planning the effective targeted antimicrobial treatment of postoperative infections requires accurate identification of the microorganism responsible for the complications of the procedure. The modern microbiological testing techniques described in this article show the diagnostic options that can be followed to enable the implementation of effective treatment.

Ideal Timing of Reimplantation in Patients with Periprosthetic Knee Infection Undergoing 2-Stage Exchange: A Diagnostic Scoring System

BACKGROUND

This study evaluated appropriate thresholds for serum biomarkers, synovial fluid white blood cell (SF-WBC) count, and synovial fluid neutrophil (polymorphonuclear leukocyte [PMN]) percentage to predict infection in a patient group who underwent definitive reimplantation after receiving a continuous course of antibiotic therapy for chronic knee periprosthetic joint infection (PJI). These thresholds were then used to generate a scoring system to predict recurrence (or persistence) of infection.

METHODS

The study included 153 patients with a median age of 73 years (range, 46 to 91 years) who underwent 2-stage revision for chronic knee PJI. Staphylococci were identified at baseline in 107 (70%) of the patients. After the 96-week follow-up period, 12% (19) of the 153 patients had recurrence of the PJI. A receiver operating characteristic (ROC) curve analysis was used to assess the predictive value of common serum biomarkers and SF aspiration before reimplantation, and the area under the curve (AUC) was evaluated. Variables that were significantly different between patients with and without infection recurrence were evaluated using a multivariable logistic regression model. A half-integer-point scoring system was created based on the final beta coefficients.

RESULTS

Regarding the prediction of recurrent infection, a D-dimer level of >1110 ng/mL yielded a sensitivity of 74%, specificity of 61%, and AUC of 0.69; an SF-WBC count of >934 cells/µL showed a sensitivity of 68%, specificity of 90%, and AUC of 0.79; and an SF-PMN percentage of >52% showed a sensitivity of 73%, specificity of 90%, and AUC of 0.82. The beta coefficients were approximated to 1.5 for the D-dimer level and to 2 for the SF-WBC count and SF-PMN percentage. A total score of >2 was used to classify patients with a high risk of infection recurrence. The ability to discriminate infection recurrence was demonstrated by an AUC of 0.90 (95% confidence interval: 0.82 to 0.99).

CONCLUSIONS

Patients with a score of >2 on our proposed scoring system based on serum biomarkers, SF-WBC count, and SF-PMN percentage should not undergo reimplantation, as they are at a high risk for recurrent PJI. Patients with a score of ≤2 can undergo definitive reimplantation with the lowest risk of recurrence.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Detection of Cutibacterium (Propionibacterium) acnes in orthopaedic surgery: serious problem or contamination?

PURPOSE

Bone and joint infections are an important and increasing problem. Whether intraoperatively detected bacteria should be considered relevant or not is often difficult to assess. This retrospective cohort study analyzes the relevance of C. acnes cultured from deep intraoperative specimens.

METHODS

All deep tissue samples collected intraoperatively between 2015 and 2020 from a quartiary care provider were evaluated for detection of C. acnes and its therapeutical consequences. Infection rates were determined according to a standardized definition and protocol and analyzed in dependence of patient's demographic data (age and gender), operative parameters (type of surgery, body region/location of surgery, and impression of the surgeon), and initiated therapy.

RESULTS

In 270 cases of more than 8500 samples, C. acnes was detected. In 30%, the detection was considered an infection. The number of samples taken and tested positive for C. acnes correlated significantly with its classification as a cause of infection. If more than one sample of the patient was positive, the detection was significantly more likely to be treated as infection (p < 0.001). In 76% of cases, a consultation to the infectious diseases (ID) department took place regarding the classification of the pathogen detection and the therapy to be carried out. Almost all of the tested isolates demonstrated the wild-type susceptibility for penicillin and clindamycin.

CONCLUSION

Intraoperative detection of skin-colonizing bacteria such as C. acnes is not always synonymous with infection. In particular, if other examination results contradict an infection (pathological sample without evidence of an infectious event, detection of malignant cells, etc.), the situation must be considered in a very differentiated manner. Interdisciplinary boards, for example, are suitable for this purpose. Care should be taken to obtain a sufficiently large number of tissue samples for microbiological examination to be able to better classify the result.

Exploring Nanotechnology as a Strategy to Circumvent Antimicrobial Resistance in Bone and Joint Infections

Bone and joint infections (BJIs) are difficult to treat, necessitating antimicrobial therapy at high doses for an extended period of time, in some cases different from our local guidelines. As a consequence of the rise in antimicrobial-resistant organisms, drugs that were previously reserved for last-line defense are now being used as first line treatment, and the pill burden and adverse effects on patients are leading to nonadherence, encouraging antimicrobial resistance (AMR) to these last-resort medicines. Nanodrug delivery is the field of pharmaceutical sciences and drug delivery which combines nanotechnology with chemotherapy and/or diagnostics to improve treatment and diagnostic outcomes by targeting specific cells or tissues affected. Delivery systems based on lipids, polymers, metals, and sugars have been used in an attempt to provide a way around AMR. This technology has the potential to improve drug delivery by targeting the site of infection and using the appropriate amount of antibiotics to treat BJIs caused by highly resistant organisms. This Review aims to provide an in-depth examination of various nanodrug delivery systems used to target the causative agents in BJI.

Intravenous antibiotic duration in the treatment of prosthetic joint infection: systematic review and meta-analysis

Introduction: Long antibiotic courses, including intravenous (IV) and oral administrations, are utilized in prosthetic joint infection (PJI) treatment. This meta-analysis examines the non-inferiority of short courses ( <  4 weeks) of IV antibiotics compared to long courses in treating PJI. Critical review of IV treatment is necessary due to the clinical, physical, and financial burden associated with it and its continued prolonged use in the US without much evidence to support the practice. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), databases were searched using predefined medical subject headings (MeSH). Results: The nine included studies reported 521 total hip arthroplasties (THAs) and 530 total knee arthroplasties (TKAs). There was no significant difference in the overall success rate in short- vs. long-duration IV antibiotics for PJI treatment: odds ratio (OR) of 1.65, 95 % confidence interval (CI) of 0.78-3.46, and p = 0 .18. However, due to the moderate to high heterogeneity (I 2 = 68  %, p   <  0.01) amongst studies, an adjusted success rate was calculated after the exclusion of two studies. This showed a statistically significant difference between both groups (OR of 2.45, 95 % CI of 1.21-4.96, p   <  0.001) favoring a short course of antibiotics and reflecting a more homogenous population (I 2 = 51  %, p = 0 .06). Conclusion: This study highlights the limited data available for evaluating IV antibiotic duration in the setting of PJI. We found that a shorter duration of IV antibiotics was non-inferior to a longer duration, with an improved OR of 2.45 for treatment success, likely shortening inpatient stay as well as lessening side effects and antimicrobial resistance with a lower cost to patients and overall healthcare.

Factors associated with late microbiological documentation of prosthetic joint infection

Purpose: To describe the number of prosthetic joint infections (PJIs) with late documentation and to identify associated factors. Methods: Bacterial PJIs with surgical management between November 2015 and November 2019 in a French center were analyzed. Results of short (72 h) and late culture (at 14 days) were analyzed. Results: A total of 160 PJIs were reported with 215 bacteria. Twenty-nine patients had late documentation (18.1%). The bacteria most involved were coagulase-negative staphylococci and Cutibacterium spp. (60%). In multivariate analysis, late chronic PJI (odds ratio = 2.47) and antibiotic therapy before surgery (odds ratio = 3.13) were associated with late-documented infection. Conclusion: A better knowledge of the factors associated with late-documented infections is essential in order to simplify antibiotic treatment at the appropriate time.

Prosthetic joint infection diagnosis applying the three-level European Bone and Joint Infection Society (EBJIS) approach

Sensitive and specific tests for the diagnosis of prosthetic joint infection (PJI) are lacking. The aim of this study was to report clinical and microbiological findings of consecutive patients diagnosed with PJI at the University Hospital of Perugia, Perugia, Italy, and to validate these diagnoses utilizing the European Bone and Joint Infection Society (EBJIS) three-level diagnostic approach from 2021. Patients with a PJI diagnosis were included in this study and examined retrospectively. Overall, 133 patients were diagnosed with PJI: mean age 72 years, 54.9% female, and 55.6% with more than one comorbidity. The most frequent involved joints were hip 47% and knee 42%. Aetiology was identified in 88/133 (66.2%): staphylococci resulted the most frequent microorganisms and over 80% (45/54) resulted rifampin susceptible. Applying the EBJIS approach, PJI diagnosis resulted: confirmed in 101 (75.9%), likely in 25 (18.8%), and unlikely in 7 (5.3%). Likely PJIs aetiology was Staphylococcus aureus 11/25, coagulase-negative staphylococci 8/25, Streptococcus agalactiae 3/25, viridans group streptococci 2/25, and Pseudomonas aeruginosa 1/25. No statistically significant differences were detected among the three diagnosis groups with regard to clinical characteristics with the exception of a higher number of confirmed PJIs occurring < 3 months after implantation. The logistic regression analysis did not disclose any independent predictor of confirmed PJIs. We recommend using all the diagnostic tests available to approach PJI diagnosis, and suggest caution before rejecting PJI diagnosis in the presence of highly virulent microorganisms from a single sample, in patients without sinus tract, and in those receiving antimicrobial at the time microbiologic samples are collected. Study approved by Umbrian Regional Ethical Committee, Perugia, Italy, Prot. N. 23,124/21/ON of 10.27.2021.

Candida periprosthetic infection of the knee: a systematic review of surgical treatments and clinical outcomes

BACKGROUND

Candida periprosthetic joint infections (PJIs) are a rare cause of prosthesis revision with severe consequences and challenging treatment. This study aims to produce a systematic analysis of types of treatment and outcome of knee Candida PJIs and their correlation with specific pathogen species.

METHODS

During April 2021, a literature search was performed according to PRISMA (Preferred Reporting Item for Systematic Reviews and Meta-Analyses) guideline. Reviewers used the Oxford Level of Evidence (LoE) and Methodological index for non-randomized studies (MINORS) score. Modal value of surgical, pharmacological treatment and outcome along with the correlation between types of treatment and outcome was calculated through Chi-square or Fisher exact test.

RESULTS

In total, 115 cases were collected through 51 articles, identifying 116 pathogens. Candida albicans was the most frequent pathogen. Analysis of LoE reveals 40 LoE 5 and 11 LoE 4. Thirteen patients underwent one-stage revision, 46 patients two-stage revision, 6 patients resection arthroplasty and arthrodesis, 4 patients long-term antifungal therapy, and 3 patients debridement with prosthesis retention. Global rate of success was 85.14%. Modal distribution revealed a preference for two-stage revision and Fluconazole in medical therapy. No difference in terms of fungal eradication was found among Candida species (p = 0.503) and for treatments except for two-stage revision and resection arthroplasty (p  = 0.0125) or debridement with implant retention (p  = 0.0498), and the rest of procedures and resection arthroplasty (0.0192). MINORS score was poor.

CONCLUSIONS

Analysis of the literature did not highlight any difference between types of surgical treatment and pathogens in terms of relapse or infection eradication. However, two-stage replacement may be preferred, allowing healing of infection in most cases.

Molecular Tools for Guiding Therapy in Patients With Staphylococcal Bone and Joint Infections: A Diagnostic Test Accuracy Meta-analysis

BACKGROUND

Timely detection of causative pathogens and their antimicrobial resistance are essential for guiding targeted therapies in bone and joint infections (BJI) patients. We performed a systematic review and meta-analysis to assess the diagnostic value of testing osteoarticular samples with the nucleic acid amplification tests (NAAT) for effective staphylococcal strain identification and the administration of appropriately targeted antimicrobial agents in BJI patients.

METHODS

Five databases, including PubMed, Embase, Scopus, Web of Science, and the Cochrane Library, were searched for related publications from inception to July 24, 2021. Studies comparing the diagnostic accuracy of NAAT to a microbiological culture reference standard of osteoarticular specimens were eligible. Pooled summary values of sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) of NAAT compared to the microbiological culture reference standard were calculated using bivariate random-effects meta-analyses.

RESULTS

From 906 citations, 11 studies were included. Eleven studies comprising 13 datasets (n = 1047) evaluated NAAT accuracy for methicillin-sensitive Staphylococcus aureus (MSSA) identification, while seven studies comprising nine datasets (n = 727) evaluated methicillin-resistant Staphylococcus aureus (MRSA) identification. Against the microbiological culture reference standard, the pooled summary estimates for detection of both MSSA [sensitivity: 0.89 (95% confidence interval [CI] 0.84-0.93), specificity: 0.99 (95% CI 0.97-0.99), PLR: 34.13 (95% CI 20.54-56.73), NLR: 0.19 (95% CI 0.12-0.3), and DOR: 283.37 (95% CI 129.49-620.1)] and MRSA [sensitivity: 0.81 (95% CI 0.67-0.91), specificity: 1.0 (95% CI 0.99-1.0), PLR: 62.1 (95% CI 24.5-157.6), NLR: 0.33 (95% CI 0.16-0.69), and DOR: 300.25 (95% CI 85.01-1060.5)] were comparable. Heterogeneity was moderate. GeneXpert was frequently used among NAA tests, and its diagnostic accuracy was in line with the overall pooled summary estimates. The heterogeneity in diagnostic efficacy (P >0.05) could not be explained by a meta-regression and subgroup analysis of the research design, sample condition, and patient selection technique.

CONCLUSIONS

Our study suggested that NAAT can be applied as the preferred prescreening test for the timely diagnosis of staphylococcal strains associated with BJI in osteoarticular samples for successful antimicrobial therapy.

Diagnosis and management of infected arthroplasty

Periprosthetic joint infection (PJI) is one of the most dreadful complications after THA and TKA. Though prevention is of utmost importance in PJI management, the last decade has seen many remarkable developments in PJI diagnosis, including the introduction of several standardized PJI diagnostic definitions and biomarkers. Depending on the specific clinical situation, a myriad of treatment options for PJI are offered. Our review aims to summarize the pertinent information on PJI diagnosis and synthesize literature on the different treatment methods currently used in clinical practice. One of the most accepted PJI diagnostic definitions was developed by the Musculoskeletal Infection Society (MSIS) in 2011, later modified in the 2013 International Consensus Meeting (ICM). After promising results from studies, alpha-defensins and D-dimer were recently incorporated into the 2018 ICM PJI definition. The management choices for PJI include irrigation and debridement (DAIR), one-stage exchange arthroplasty, or two-stage exchange arthroplasty, to name a few. While two-stage revision has traditionally been the treatment of choice in the United States, there has been a growing body of evidence framing one-stage revision as a comparable choice. One-stage revision should be offered in patients meeting strict selection criteria: no sinus tract, proper soft tissue available for wound closure, appropriate bone stock, a favorable identifiable organism with encouraging antibiotic sensitivities (for cement and oral suppression later), and robust immunological status. DAIR can be considered in case of early infections with sensitive infecting organisms. Patients with multiple unsuccessful revisions or those who refuse further surgical intervention for PJI can be offered antibiotic suppression. If nothing seems to work, salvage procedures (resection arthroplasty and arthrodesis) are available as a last resort. Further research is encouraged to improve on diagnostic capabilities and develop evidence on the best treatment of choice for PJI.

Synovial Cell Count Before Reimplantation Can Predict the Outcome of Patients with Periprosthetic Knee Infections Undergoing Two-stage Exchange

BACKGROUND

Although synovial fluid can be used to diagnose periprosthetic joint infections (PJI) effectively, only the cutoff values adopted at the time of PJI diagnosis have been standardized, and few data are currently available about effectiveness of synovial fluid examination before definitive reimplantation.

QUESTIONS/PURPOSES

We asked: (1) What are the most appropriate thresholds for synovial fluid leukocyte counts (WBC) and neutrophil percentage (PMN percentage) in a patient group undergoing definitive reimplantation after an uninterrupted course of antibiotic therapy for chronic PJI? (2) What is the predictive value of our synovial WBC and PMN percentage threshold compared with previously proposed thresholds?

METHODS

In all, 101 patients with PJI were evaluated for inclusion from January 2016 to December 2018. Nineteen percent (19 of 101) of patients were excluded because of the presence of a chronic inflammatory disease, acute/late hematogenous infection, low amount of synovial fluid for laboratory investigations or infection persistence after spacer placement, and adequate antibiotic therapy. Finally, 81% (82 of 101) of patients with a median (range) age of 74 years (48 to 92) undergoing two-stage revision for chronic TKA infection, who were followed up at our institution for a period 96 weeks or more, were included in this study. The patients did not discontinue antibiotic treatment before reimplantation and were treated for 15 days after reimplantation if intraoperative cultures were negative. No patient remained on suppressive treatment after reimplantation. Synovial fluid was aspirated aseptically with a knee spacer in place to evaluate the cell counts before reimplantation. Thirteen percent (11 of 82) of patients had persistent or recurrent infection, defined as continually elevated erythrocyte sedimentation rate or C-reactive protein levels coupled with local signs and symptoms or positive cultures. The synovial fluid WBC counts and PMN percentage from the 11 patients with persistent or recurrent PJI were compared with the 71 patients who were believed to be free of PJI. Receiver operating characteristic (ROC) curve analyses assessed the predictive value of the parameters, and the areas under the curves (AUCs) were evaluated. The sensitivities, specificities, and positive and negative predictive values were determined for the WBC count and PMN percentage. Patients with persistent or recurrent infection had higher median WBC counts (471 cells/µL versus 1344 cells/µL; p < 0.001) and PMN percentage (36% versus 61%; p < 0.001) than did patients believed to be free of PJI.

RESULTS

ROC curve analysis identified the best threshold values to be a WBC count of 934 cells/µL or more (sensitivity 0.82 [95% CI 0.71 to 0.89], specificity 0.82 [95% CI 0.71 to 0.89]) as well as a PMN percentage of at least 52% (sensitivity 0.82 [95% CI 0.71 to 0.89] and specificity 0.78 [95% CI 0.67 to 0.86]. We found no difference between the AUCs for the WBC count and the PMN percentage (0.87 [95% CI 0.79 to 0.96] versus 0.84 [95% CI 0.73 to 0.95]. Comparing the sensitivities and specificities of the synovial fluid WBC count and PMN percentage proposed by other authors, we find that a PMN percentage more than 52% showed better predictive value than previously reported.

CONCLUSION

Based on our findings, we believe that patients with WBC counts of at least 934 and PMN percentage of 52% or more should not undergo reimplantation but rather a repeat debridement, as their risk of persistent or recurrent PJI appears prohibitively high. The accuracy of the proposed cutoffs is better than previously reported.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Periprosthetic infections: How do we diagnose and treat? Results of an online survey and comparison with international recommendations

Objective

Endoprosthetic replacement surgery of hip and knee joints is widely performed, but always carries the risk of developing periprosthetic infection (PPI). Treatment of PPI is lengthy and demanding for the patient, often involving multiple surgeries as well as lengthy drug therapies. Remediation is not always successful despite extensive therapy.

Methods

An online survey was used to investigate whether the therapeutic measures implemented in German hospitals are based on international treatment recommendations. For this purpose, German physicians who regularly treat periprosthetic infections in their clinics were asked to complete an online questionnaire. The questionnaire asked about internal hospital procedures. These were then compared with international recommendations.

Results

With a response rate of 10.9%, the questionnaire shows agreement with the international recommendations in large parts of the operative and medicinal procedures. In preoperative imaging for example, two‐plane radiographs are the standard. Similarly, the participants' approach to preoperative specimen collection, incubation time, and operative management (regarding one‐ or two‐stage approach to septic joint) reflects the recommendations.

Deviations were particularly evident in the area of laboratory diagnostics, where the erythrocyte sedimentation rate (ESR) is determined in only 17.1%, contrary to the recommendations. Whereas procalcitonin (PCT) and blood culture sampling takes place regularly. Clear differences emerges in the use of drains, which, contrary to the recommendations, are used very regularly (almost 70%).

In this survey, the time intervals between the onset of infection symptoms and the start of therapy (prosthesis‐preserving therapy) is shown to be longer than recommended internationally.

Conclusion

In summary, however, the recommended approaches of the international groups in most respects are followed, a high willingness of respondents to collaborate with local infectious disease specialists demonstrates the complexity of the disease.

Low prevalence of tissue detection of cefepime and daptomycin used as empirical treatment during revision for periprosthetic joint infections: results of a prospective multicenter study

Data demonstrating that antibiotics administered intraoperatively in patients with surgical revision for periprosthetic joint infection achieve concentrations exceeding minimal inhibitory concentrations of the identified bacteria at the surgical site when the new implant is inserted are lacking. We prospectively included patients with periprosthetic joint infection operated with one- or two-stage replacement during which cefepime (2g)-daptomycin (10mg/kg) combination was administered intravenously as intraoperative empirical antibiotic treatment. Three biopsies (two bones and one synovial membrane) were taken from each patient just before the insertion of the new implant. Eighteen adults of median age 68 years were included. Knee was involved in 10 patients (55.6%) and surgery consisted in one-/two-stage replacement in 11/7 patients. A tourniquet was used during the intervention in the 10 patients with knee prosthesis. Among 54 tissue samples, cefepime and daptomycin were detected respectively in 35 (64.8%) and 21 (38.9%) cases (P=0.01). A total of 17 bacteria dominated by staphylococci (n=14) were identified in 10 patients; tissue inhibitory quotient calculated in 51 samples was >1 in 22 cases (43.1%) for cefepime and in 16 cases (31.4%) for daptomycin. The proportion of tissue samples with detectable antibiotic was significantly higher in hip versus knee prosthesis (P=0.03). The present study suggests that intraoperative empirical administration of cefepime-daptomycin combination during septic prosthetic joint replacement results in a high proportion of tissue samples in which at least one of the two antibiotics was not detected or at a low concentration despite satisfactory concomitant blood serum concentrations.

Establishment of an interdisciplinary board for bone and joint infections

PURPOSE

The incidence of bone and joint infections is increasing while their treatment remains a challenge. Although guidelines and recommendations exist, evidence is often lacking and treatment complicated by complex clinical presentations and therapeutic options. Interdisciplinary boards shown to improve management of other diseases, seem potentially helpful. We describe the establishment of an osteomyelitis board to show the existing demand for such a platform.

METHODS

All patients discussed in the board for bone and joint infections between October 2014 and September 2020 were included in this retrospective study. Data were extracted from patient records and analyzed descriptively.

RESULTS

A total of 851 requests related to 563 patients were discussed in the board during the study period. After a run-in period of 3 years, a stable number of cases (> 170/year) were discussed, submitted by nearly all hospital departments (22 of 25). Recommendations were mainly related to antibiotic treatment (43%) and to diagnostics (24%). Periprosthetic joint infections were the most frequent entity (33%), followed by native vertebral osteomyelitis and other osteomyelitis. In 3% of requests, suspected infection could be excluded, in 7% further diagnostics were recommended to confirm or rule out infection.

CONCLUSIONS

A multidisciplinary board for bone and joint infections was successfully established, potentially serving as a template for further boards. Recommendations were mainly related to antibiotic treatment and further diagnostics, highlighting the need for interdisciplinary discussion to individualize and optimize treatment plans based on guidelines. Further research in needed to evaluate impact on morbidity, mortality and costs.

Current trends in the real-life use of dalbavancin: report of a study panel

Dalbavancin is a novel lipoglycopeptide antibiotic with a chemical structure similar to teicoplanin. Dalbavancin has been approved and marketed since 2014 in the USA and 2015 in the European Union for the treatment of acute bacterial skin and skin-structure infections (ABSSSIs) caused by Gram-positive cocci. ABSSSIs include infectious syndromes such as erysipelas, cellulitis, major cutaneous abscesses that require incision and drainage, and both surgical and traumatic wound infections. In current clinical practice, dalbavancin is also used for cardiac implantable electronic device-related soft tissue infection and other prosthetic infections, and therefore when the presence of biofilm is a concern. In this review, we aimed to highlight our experience with the use of dalbavancin for some of the most hard-to-treat Gram-positive infections, as well as a promising strategy in terms of pharmacoeconomic effectiveness. We describe our current real-life clinical practice with the use of dalbavancin, depicting a few representative clinical cases in order to share our own practice in the hospital setting.

An evidence based narrative review on treatment of diabetic foot osteomyelitis

OBJECTIVE

The diagnosis of diabetic food infection is usually clinical, and its severity is related to location and depth of the lesion, and the presence of necrosis or gangrene. Osteomyelitis of the foot and ankle can be extremely debilitating, and, in the preantibiotic era acute staphylococcal osteomyelitis carried a mortality rate of 50%. The microbiology of diabetic foot osteomyelitis (DFO) is usually polymicrobial. Indeed, gram-negative and gram-positive bacilli can be identified using molecular techniques applied to bone biopsies compared to conventional techniques. The aim of the present study is to report a complete overview regarding medical and surgical management of diabetic foot osteomyelitis (DFO) in combination or alone.

MATERIALS AND METHODS

We performed a search in PubMed and Scopus electronic databases (up to January 2019) of articles assessing the epidemiology, diagnostic strategy and pharmacological treatment of diabetic foot infection. In the search strategy, we used various combinations of the following key terms: infection, orthopaedic, diabetic foot, management, DFO.

RESULTS

This article discusses the definition, epidemiology, microbiological assessment, clinical evaluation, pharmacological and surgical management and a comparison between them, of DFO. After the initial literature search and removal of duplicate records, a total of 756 potentially relevant citations were identified. After a further screening and according to the inclusion criteria, a total of 65 articles were included in the present review.

CONCLUSION

The association of antibiotic and surgical therapy seems to be more effective compared to each one alone. The lack of comparison studies and randomized controlled trials makes it difficult to give information about the efficacy of the different management therapies.

The Right Time to Safely Re-Evaluate Empirical Antimicrobial Treatment of Hip or Knee Prosthetic Joint Infections

Currently, no guideline provides recommendations on the duration of empirical antimicrobial treatment (EAT) in prosthetic joint infection (PJI). The aim of our study was to describe the time to growth of bacteria involved in PJI, rendering possible decreased duration of EAT. Based on a French multicentre prospective cohort study, culture data from patients with confirmed hip or knee PJI were analysed. For each patient, five samples were processed. Time to positivity was defined as the first positive medium in at least one sample for virulent pathogens and as the first positive medium in at least two samples for commensals. Definitive diagnosis of polymicrobial infections was considered the day the last bacteria were identified. Among the 183 PJIs, including 28 polymicrobial infections, microbiological diagnosis was carried out between Day 1 (D1) and D5 for 96.7% of cases. There was no difference in the average time to positivity between acute and chronic PJI (p = 0.8871). Microbiological diagnosis was given earlier for monomicrobial than for polymicrobial infections (p = 0.0034). When an optimized culture of peroperative samples was carried out, almost all cases of PJI were diagnosed within five days, including polymicrobial infections. EAT can be re-evaluated at D5 according to microbiological documentation.

Probabilistic chemotherapy in knee and hip replacement infection: the place of linezolid

Prosthetic joint infection (PJI) can occur with a wide range of microorganisms and clinical features. After replacement surgery of prosthetic joint, prescription of probabilistic broad-spectrum antimicrobial therapy is usual, while awaiting microbial culture results. The aim of our study was to describe the antibiotic susceptibility of microorganisms isolated from hip and knee PJI. The data were collected to determine the best alternative to the usual combination of piperacillin-tazobactam (TZP) or cefotaxime (CTX) and vancomycin (VAN). Based on a French prospective, multicenter study, we analyzed microbiological susceptibility to antibiotics of 183 strains isolated from patients with confirmed hip or knee PJI. In vitro susceptibility was evaluated: TZP+VAN, TZP+linezolid (LZD), CTX+VAN, and CTX+LZD. We also analyzed resistance to different antibiotics commonly used as oral alternatives. Among the 183 patients with PJI, 62 (34%) had a total knee prosthesis, and 121 (66%) a hip prosthesis. The main identified bacteria were Staphylococcus aureus (32.2% of isolates), coagulase-negative staphylococci (27.3%), Enterobacteriaceae (14.2%), and Streptococcus (13.7%). Infections were polymicrobial for 28 (15.3%) patients. All combinations were highly effective: CTX+VAN, CTX+LZD, TZP+VAN, and TZP+LZD (93.4%, 94%, 98.4%, and 98.9% of all cases respectively). Use of LZD instead of VAN in combination with a broad-spectrum beta-lactam covers almost all of the bacteria isolated in PJI. This association should be considered in probabilistic chemotherapy, as it is particularly easy to use (oral administration and no vancomycin monitoring).

Continuous Antibiotic Therapy Can Reduce Recurrence of Prosthetic Joint Infection in Patients Undergoing 2-Stage Exchange

BACKGROUND

Reimplantation microbiology and serum C-reactive protein have low diagnostic accuracy in predicting recurrence in patients with prosthetic joint infection (PJI) undergoing 2-stage exchange. We aimed at identifying factors relating to failure and comparing effect of continuous antibiotic therapy versus a holiday antibiotic period pre-reimplantation.

METHODS

This observational study included patients with PJI undergoing 2-stage exchange. Group A patients did not discontinue antibiotic treatment pre-reimplantation; in group B patients, antibiotic treatment was followed with 2 weeks of holiday antibiotic period pre-reimplantation. We defined cure as absence of recurrence for 96 weeks post-reimplantation. Statistical analyses were performed using Mann-Whitney U test, Fisher exact test, and multivariate analysis.

RESULTS

We evaluated 196 patients with PJI (median age, 66 years [interquartile range, 59-72], 91 [46%] males). Comorbidity was reported in 77 (39%), and microbiologic evidence was obtained in 164 (84%). Staphylococcus aureus was isolated in 63 of 164 (38%) patients; coagulase-negative staphylococci were isolated in 71 of 164 (43%). Favorable outcome was achieved for 169 (86%) patients (91% and 79% in groups A and B, respectively). No immunocompromise (odds ratio [OR], 2.73; 95% confidence interval [CI], 1.3-7.3; P = .04), a positive culture (OR, 3.96; 95% CI, 1.55-10.19; P = .02), and no antibiotic discontinuation (OR, 3.32; 95% CI, 1.3-8.44; P = .02) predicted favorable outcome using multivariate analysis.

CONCLUSION

Treatment with continuous antibiotic therapy ameliorated success rate, permitting a better outcome in immunocompromised and reducing the time to reimplantation. Continuous antibiotic therapy can be considered a valid option for the treatment of patients with PJI undergoing 2-stage exchange.

LEVEL OF EVIDENCE

Therapeutic level II.

Identifying Common Pathogens in Periprosthetic Joint Infection and Testing Drug-resistance Rate for Different Antibiotics: A Prospective, Single Center Study in Beijing

OBJECTIVE

The aim of this study is to identify the common microorganisms causing PJI as well as the drug-resistant spectrum for each microorganism, to help orthopaedic surgeons to choose appropriate antibiotics.

METHOD

One hundred and sixty patients who suffered from failure of primary or revision total hip or knee arthroplasty for different reasons were prospectively recruited. These patients underwent revision or re-revision total hip or knee arthroplasty in our institution between August 2013 to August 2016. The details of patients' medical history and comprehensive physical examination, as well as demographic data were recorded precisely. Routine blood test results, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), high sensitive C-reactive protein (hs-CRP), interleukin-6 (IL-6) levels, and synovial leukocyte counts were collected. Additionally, aspiration was conducted during surgery to avoid pollution unless when PJI was strongly suspected, in which case, joint puncture and aspiration were conducted before surgery. Intraoperatively, the implant-surrounding tissue and the prosthesis were collected under aseptic conditions. Postoperatively, the prosthesis, implant-surrounding tissue and synovium were sent to the laboratory immediately. The sonicate extraction (the prosthesis was sent for ultrasound sonication first), implant surrounding tissue and synovium were sent for microbiologic culture, and the implant-surrounding tissue was also sent for pathological examination. The isolated bacteria strains and drug-resistance rates for each pathogen for different antibiotics were presented.

RESULTS

There were 59 PJI cases in the infectious group and 101 cases in the non-infectious group (PJI is diagnosed according to the diagnosing criteria from the Workgroup of the Musculoskeletal Infection Society). Of 69 strains of pathogens isolated, Gram-positive bacterium is the most common pathogenic bacteria causing PJI (60, 86.96%). Staphylococcus epidermidis and Staphylococcus aureus played an important role as well, followed by Gram-negative bacteria (8, 11.59%) and fungus (1, 1.45%). Penicillin (78.57%), erythromycin (66.67%) and clindamycin (44.74%) showed high antibiotic resistance rate. In addition, the second-generation cephalosporin, usually as the prophylactic antibiotic, resistance rate was high (20%) as well. Fortunately, no vancomycin-resistant bacteria were discovered in the current study.

CONCLUSION

This study provides some information on the most common pathogens in our institution and the selection of antibiotics in the perioperative period in northern China. Cefuroxime and clindamycin might not be appropriate for use as prophylactic antibiotics in revision total knee or hip arthroplasty. Vancomycin is ideal for empiric antibiotic use in suspected PJI cases because of the low drug-resistance rate.

Periprosthetic Infection in Joint Replacement

BACKGROUND

The volume of joint replacement surgery has risen steadily in recent years, because the population is aging and increasingly wishes to reserve a high functional status onward into old age. Infection is among the more common complications of joint replacement surgery, arising in 0.2% to 2% of patients, or as many as 9% in special situations such as the implantation of megaprostheses. The associated morbidity and mortality are high. It is thus very important to minimize risk factors for infection and to optimize the relevant diagnostic and therapeutic strategies.

METHODS

This review is based on pertinent publications retrieved by a selective search in PubMed, including current guidelines and expert recommendations.

RESULTS

The crucial diagnostic step is joint biopsy for the identification of the pathogenic organism, which succeeds with over 90% sensitivity and specificity. If the prosthesis is firmly anchored in bone, the pathogen is of a type that responds well to treatment, and symptomatic infection has been present only for a short time, then rapidly initiated treatment can save the prosthesis in 35-90% of cases. The pillars of treatment are thorough surgical care (radical débridement) and targeted antibiotic therapy. On the other hand, if the prosthesis is loose or the pathogen is of a poorly treatable type, the infection can generally only be cured by a change of the prosthesis. This can be performed in either one or two procedures, always in conjunction with systemic antibiotic therapy tailored to the specific sensitivity and resistance pattern of the pathogen.

CONCLUSION

The risk of infection of an artificial joint is low, but the overall prevalence of such infections is significant, as the number of implanted joints is steadily rising. Artificial joint infections should be treated by a standardized algorithm oriented toward the recommendations of current guidelines. Many of these recommendations, however, are based only on expert opinion, as informative studies providing high-grade evidence are lacking. Thus, for any particular clinical situation, there may now be multiple therapeutic approaches with apparently comparable efficacy. Randomized trials are urgently needed.

Histopathological Diagnosis of Prosthetic Joint Infection: Does a Threshold of 23 Neutrophils Do Better than Classification of the Periprosthetic Membrane in a Prospective Multicenter Study?

No gold standard exists for histopathological diagnosis of a prosthetic joint infection (PJI). The historical criterion considers the presence of neutrophil infiltration upon examination of periprosthetic tissue. Morawietz et al. proposed a classification of periprosthetic membranes (Morawietz et al., Clin Pathol 59:591-597, 2006, https://doi.org/10.1136/jcp.2005.027458) and a more recently described classification with a new cutoff value of 23 neutrophils in 10 high-power fields (Morawietz et al., Histopathology 54:847-853, 2009. https://doi.org/10.1111/j.1365-2559.2009.03313.x). We performed a multicenter prospective study, which compared both methods for the diagnosis of PJI. All suspicions of PJI (n = 264) between December 2010 and March 2012 in seven centers were prospectively included. Five perioperative specimens were collected per patient for cultures, and one was collected for histology. Diagnosis of PJI was made according to the Infectious Diseases Society of America (IDSA) guidelines. Histopathological analysis classified the patients according to the threshold of 23 neutrophils and according to the classification of Morawietz. Performances of both methods were compared by using clinical and/or bacteriological criteria as the gold standard. Among 264 patients with suspected PJI, a diagnosis of infection was confirmed in 215 and unconfirmed in 49 patients. Histopathological analysis was available for 150 confirmed PJI and 40 unconfirmed PJI cases. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 78.7%, 90.0%, 96.7%, 52.9%, and 81.1%, respectively, for the Morawietz classification, and 82.0%, 90.0%, 96.9%, 57.1%, and 83.7%, respectively, for the 23-neutrophil threshold. The new algorithm using a threshold of 23 neutrophils can be proposed as a new gold standard for the histopathological diagnosis of PJI.

Staphylococcal Osteomyelitis: Disease Progression, Treatment Challenges, and Future Directions

Osteomyelitis is an inflammatory bone disease that is caused by an infecting microorganism and leads to progressive bone destruction and loss. The most common causative species are the usually commensal staphylococci, with Staphylococcus aureus and Staphylococcus epidermidis responsible for the majority of cases. Staphylococcal infections are becoming an increasing global concern, partially due to the resistance mechanisms developed by staphylococci to evade the host immune system and antibiotic treatment. In addition to the ability of staphylococci to withstand treatment, surgical intervention in an effort to remove necrotic and infected bone further exacerbates patient impairment. Despite the advances in current health care, osteomyelitis is now a major clinical challenge, with recurrent and persistent infections occurring in approximately 40% of patients. This review aims to provide information about staphylococcus-induced bone infection, covering the clinical presentation and diagnosis of osteomyelitis, pathophysiology and complications of osteomyelitis, and future avenues that are being explored to treat osteomyelitis.

Hypokalemia during antibiotic treatment for bone and joint infections

PURPOSE

During treatment of bone and joint infections (BJIs) with multiple antibiotic therapy, hypokalemia has been reported as a rare side effect. The aim of this study was to evaluate incidence and risk factors for hypokalemia in a cohort of patients treated with multidrug therapy for BJIs, in a single center.

METHODS

We retrospectively reviewed 331 clinical files of 150 consecutive patients (65% males; median age 59 years, 95% CI 55-62) admitted repeatedly to our Osteomyelitis Department for treatment of chronic BJIs. Besides surgical debridement, patients received a combination of oral and intravenous antibiotics. Routine laboratory tests were performed at admittance and repeated at least weekly. Possible hypokalemia risk factors were recorded and analyzed.

RESULTS

Progressive kalemia reduction occurred in > 39% of patients during hospitalization; prevalence of marked hypokalemia (K ⁺ < 3.5 mEq/l) increased from 5% at admission to 11% (up to 22%) at day 14. Correlated factors were: age ≥ 68 years (p = 0.033), low serum albumin (p = 0.034), treatment with vancomycin (p < 0.001), rifampicin (p = 0.017) and ciprofloxacin (p < 0.001) and use of thiazide (p = 0.007) or loop diuretics (p = 0.029 for K ⁺ < 3.5 mEq/l). At multivariate regression analysis, the main determinants of hypokalemia were simultaneous use of diuretics (p = 0.007) and older age (p < 0.049).

CONCLUSIONS

Appearance of severe hypokalemia is a frequent event among patients treated for BJIs with multiple antibiotic therapy, when this is prescribed in older age patients and associated with simultaneous use of diuretics. Due to possible increase in mortality risk in the short term, particular caution should be paid during intensive antibiotic treatment in these groups of patients.

Accuracy of different diagnostic tests for early, delayed and late prosthetic joint infection

BACKGROUND

A combination of laboratory, histopathological and microbiological tests for diagnosis of prosthetic joint infection (PJI) have been strongly recommended. This study aims to characterize the accuracy of individual or group tests, such as culture of sonicate fluid, synovial fluid and peri-implant tissue, C-reactive protein (CRP) and histopathology for detection of early, delayed and late PJI.

METHODS

A prospective study of patients undergoing hip or knee arthroplasty from February 2009 to February 2014 was performed in a Spanish tertiary health care hospital. The diagnostic accuracy of the different methods was evaluated constructing receiver-operating-characteristic (ROC) curve areas.

RESULTS

One hundred thirty consecutive patients were included: 18 (13.8%) early PJI, 35 (27%) delayed PJI and 77 (59.2%) late PJI. For individual parameters, the area under the ROC curve for peri-implant tissue culture was larger for early (0.917) than for delayed (0.829) and late PJI (0.778), p = 0.033. There was a significantly larger difference for ROC area in the synovial fluid culture for delayed (0.803) than for early (0.781) and late infections (0.679), p = 0.039. The comparison of the areas under the ROC curves for the two microbiological tests showed that sonicate fluid was significantly different from peri-implant tissue in delayed (0.951 vs 0.829, p = 0.005) and late PJI (0.901 vs 0.778, p = 0.000). The conjunction of preoperative parameters, synovial fluid culture and CRP, improved the accuracy for late PJI (p = 0.01). The conjunction of histopathology and sonicate fluid culture increased the area under ROC curve of sonication in early (0.917 vs 1.000); p = 0.06 and late cases (0.901 vs 0.999); p < 0.001.

CONCLUSION

For early PJI, sonicate fluid and peri-implant tissue cultures achieve the same best sensitivity. For delayed and late PJI, sonicate fluid culture is the most sensitive individual diagnostic method. By combining histopathology and peri-implant tissue, all early, 97% of delayed and 94.8% of late cases are diagnosed. The conjunction of histopathology and sonicate fluid culture yields a sensitivity of 100% for all types of infection.

Oral Therapy, Microbiological Findings, and Comorbidity Influence the Outcome of Prosthetic Joint Infections Undergoing 2-Stage Exchange

BACKGROUND

The aim of the present study was to investigate potential predictive factors of an unfavorable outcome in patients with prosthetic joint infection (PJI) undergoing 2-stage exchange.

METHODS

Patients with PJI undergoing 2-stage exchange and observed over a 5-year period (2009-2013) were included. Cure was defined by the disappearance of infection after a 96-week follow-up period. Statistical analysis was performed using the Mann-Whitney U test, the Fisher exact test, and the multivariate analysis.

RESULTS

One-hundred twenty-two patients with PJI were included (median age, 69 years [range, 36-80 years]; 48% males, 47 hip PJI, and 75 knee PJI). Known comorbidities related to an increased risk of infection were reported in 43 patients (35%). Microbiological definition was obtained in 101 (83%) patients, and Staphylococcus aureus was isolated in 44 (36%) patients. Coagulase-negative staphylococci were isolated in 41 (34%) patients. A favorable outcome was obtained in 102 of 122 patients (84%). After univariate analysis, bacterial growth from operative specimens (P = .007), growth of Gram-positive bacteria (P < .001), use of oral therapy (P = .01), and absence of known comorbidities (P = .02) were associated with favorable outcome. Administration of rifampin (P = .99) and results of blood analysis were not predictive of outcome. After multivariate analysis was applied, infection sustained by Gram-positive bacteria, administration of oral antibiotics, and absence of known comorbidities frequently resulted in favorable outcome.

CONCLUSION

A favorable outcome in patients with PJI undergoing 2-stage procedure was associated with an infection sustained by Gram-positive bacteria, absence of known comorbidities, and administration of oral therapy. Therefore, failure rate can be reduced with appropriate treatment choices.

Acute periprosthetic knee infection: is there still a role for DAIR?

BACKGROUND AND AIM OF THE WORK

Periprosthetic knee infection is a rare complication associated with prosthetic failure; incidence change from 0,4-2% of primary total knee replacement and 5.6% in revisions. Indications for debridment, antibiotics and implant retention (DAIR) are early acute infections or acute delayed infection. Aim of the work is to check if this technique is still a successful in early infections.

METHODS

We have analyzed recent literature data on DAIR and all DAIR procedures in our clinic in the last 10 years, the mean time between onset of symptoms and surgery, the mean antibiotic therapy duration and results we have obtained. We evaluate the diagnostic process and different treatments in early knee periprosthetic infections, especially the DAIR approach.

RESULTS

If correct indications are followed, DAIR has a success rate in 31-100% of the cases; if it is applied in late chronic infection the success rate is 28-62%. In our experience DAIR has an 80% success rate: in 20 patients treated with DAIR we had 4 failures.

CONCLUSIONS

DAIR can be considered a successful treatment, but it depends from individual patient factors, from the microorganisms involved, from the duration of antibiotic therapy and from correct choice in timing and in execution of DAIR by the orthopedic surgeon.

Peri-Prosthetic Knee Infection Management: Spacers Loaded with Two or Three Antibiotic Agents

BACKGROUND

The purpose of this work was to compare pre-made antibiotic-loaded spacers with two commercially available antibiotic agents and custom-made cements with three antibiotic agents added. We evaluated: (a) the validity of our procedures, (b) the control of the rate of infection in the long term, (c) complications, and (d) quality of life and patient satisfaction.

METHODS

A retrospective cohort study was performed on 112 consecutively treated patients between January 2010 and December 2013; 56 patients were treated with a pre-formed cement spacer (clindamycin + gentamicin), and 56 patients were treated with a spacer loaded with three antibiotic agents (clindamycin + gentamicin + vancomycin). Demographic data were collected: Classification of infection according to criteria of Cierny-Mader; microbiologic results; number of previous operations; and years of disease. Infection control or relapse after at least 18 months of follow-up was evaluated. Complications were recorded. Every patient completed the SF-36 test and Oxford Knee Score.

RESULTS

With a follow-up of 32.87 months (standard deviation 12.04), at the end of treatment, amputation occurred in three of 112 patients because of recurrence of infection, and one patient died from other causes not related to the infection. The study population presented a rate of recurrence of infection of 2.70%.

CONCLUSIONS

Our results suggest that a two stage re-implant with three antibiotic agents added to the spacer should be considered to avoid rescue procedures, especially in patients with multi-resistant micro-organism infections.

Diagnostic and therapeutic appropriateness in bone and joint infections: results of a national survey

The impact of infectious diseases (ID) specialist consultation in the management of many types of bacterial infections has been fully demonstrated but not for bone and joint infections (BJIs). Nineteen ID Italian centres collected of data from June 2009 to May 2012. Italian guidelines (2009) were used to determine the appropriateness of the diagnostic and therapeutic process of BJIs before and after consulting an ID specialist. Data on 311 patients were collected: 111 cases of prosthetic joint infection, 99 osteomyelitis, 64 spondylodiscitis and 37 fixation device infection. A significant increase of microbiological investigations, imaging techniques and blood inflammation markers were noted after consulting the ID specialist. Moreover, inappropriateness of treatment duration, dosage, and number of administrations significantly decreased after consultation. Infectious disease specialist intervention in the management of BJIs significantly increases the appropriateness both in performing instrumental and laboratory analysis, but especially in determining the correct therapy.

Salvage Procedures for Management of Prosthetic Joint Infection After Hip and Knee Replacements

Background:

The increasing load placed by joint replacement surgery on health care systems makes infection, even with the lowest rates, a serious concern that needs to be thoroughly studied and addressed using all possible measures.

Methods:

A comprehensive review of the current literature on salvage procedures for recurrent PJIs using PubMed, EMBASE and CINAHL has been conducted.

Results:

Prolonged suppressive antibiotic therapy (PSAT), resection arthroplasty and arthrodesis were the most common procedures performed. Suppressive antibiotic therapy is based on the use of well tolerated long term antibiotics in controlling sensitive organisms. Resection arthroplasty which should be reserved as a last resort provided more predictable outcomes in the hip whereas arthrodesis was associated with better outcomes in the knee. Various methods for arthrodesis including internal and external fixation have been described.

Conclusion:

Despite good union and infection control rates, all methods were associated with complications occasionally requiring further surgical interventions.

Comparative activities of vancomycin, tigecycline and rifampin in a rat model of methicillin-resistant Staphylococcus aureus osteomyelitis

OBJECTIVES

Implant-associated methicillin-resistant Staphylococcus aureus (MRSA) infections are challenging to treat. We compared antimicrobial activities in a rat model of chronic osteomyelitis in the context of retention of the foreign body without débridement.

METHODS

MRSA was inoculated into the proximal tibia and a wire implanted. Four weeks after infection, treatment with vancomycin 50 mg/kg every 12 h, tigecycline 14 mg/kg every 12 h, rifampin 25 mg/kg every 12 h, or the combination of vancomycin or tigecycline plus rifampin was administered intraperitoneally for 21 days.

RESULTS

MRSA was cultured from all tibias in the control group (median, 6.06 log10 CFU/g bone). Median bacterial counts (log10 CFU/g) at 48 h post-treatment were 6.16 for vancomycin (p = 0.753), 2.29 for vancomycin plus rifampin (p < 0.001), 5.90 for tigecycline (p = 0.270), 0.10 for tigecycline plus rifampin (p < 0.001), and 0.91 for rifampin (p = 0.044) treatment. Three deaths were observed in the tigecycline plus rifampin group. Median bacterial counts (log10 CFU/g) at two weeks post-treatment were 5.65 for vancomycin (p = 0.6), 4.05 for vancomycin plus rifampin (p = 0.105), 5.68 for tigecycline (p = 0.401), 4.05 for tigecycline plus rifampin (p = 0.028), and 5.98 for rifampin (p = 0.297) treatment.

CONCLUSIONS

Tigecycline plus rifampin resulted in a significant bacterial count decrease, an effect more prominent at 48 h than two weeks after treatment completion. Tigecycline was not well tolerated at the dose studied.

Factors related to outcome of early and delayed prosthetic joint infections

In this prospective study, we evaluate the impact of adherence to a diagnostic and therapeutic protocol on prosthetic joint infections (PJI) diagnostic accuracy and outcome.

PATIENTS AND METHODS

Patients with early or delayed PJI referred over a 5-year period were included. Diagnosis was based on characteristic clinical signs, radiographic findings and microbiological evidence. Antibiotics were chosen on the basis of microbiological findings, and drugs active against methicillin-resistant staphylococci were administered if no microbiological evidence had been obtained.

RESULTS

Inclusion criteria were met in 159 cases (median age 64 years, males 45%). 56 were early infections and 103 delayed infections. Comorbidities were reported in 99 (62%) cases. Positive cultures were obtained in 122/159 (77%), coagulase-negative staphylococci were cultured in 20%, Staphylococcus aureus in 28%, and Pseudomonas aeruginosa in 7%. In early infections, cure rate after debridement and antibiotic therapy was 80%. In delayed infections, cure rate after two-stage exchange was 85%. Of 28 patients with delayed infection treated with antibiotics without surgery, only 8 (29%) infections were suppressed 48 weeks after treatment discontinuation. Rifampin afforded a better outcome.

CONCLUSION

Appropriate diagnostic and surgical procedures and microbiologically driven antibiotic therapy including rifampin are recommended to improve diagnostic accuracy and outcome.

Clinical guidelines for the antimicrobial treatment of bone and joint infections in Korea

There are many various diseases in the bone and joint infections, and we tried to make antimicrobial treatment guidelines for common infectious diseases based on available data for microbiology and clinical trials. This guidelines focused on the treatment of osteomyelitis and septic arthritis, which can be experienced by physicians at diverse clinical settings. This guidelines is not applicable to diabetic foot infections, postoperative infections or post-traumatic infections which need special considerations. The guidelines for those conditions will be separately developed later. Surgical treatment of bone and joint infections, pediatric bone and joint infection, tuberculous bone and joint infection, and prophylactic antibiotic use were not included in this guideline.

Infected primary knee arthroplasty: Risk factors for surgical treatment failure

Objective

To present epidemiological data and risk factors associated with surgical outcomes favorable or unfavorable for the treatment of infection in infected total knee arthroplasty.

Methods

We reviewed medical records of 48 patients who underwent treatment of primary total knee arthroplasty for infection between January 1994 and December 2008, in the Orthopedics and Traumatology Department of the Santa Casa de Misericórdia de São Paulo. The variables associated with favorable outcome of surgical treatment (debridement and retention or exchange arthroplasty in two days) or unfavorable (arthrodesis or death) infection.

Results

A total of 39 cases of infection after primary total knee arthroplasty, 22 progressed to 17 for a favorable outcome and unfavorable outcome. Early infections (OR: 14.0, 95% CI 1.5–133.2, p = 0.016) and diabetes (OR: 11.3, 95% CI 1.4–89.3, p = 0.032) were associated with arthrodesis joint and death respectively.

Conclusion

Patients with early infection had a higher risk of developing surgical procedure with unfavorable outcome (arthrodesis) and diabetics had higher odds of death after infection of primary knee arthroplasties.

Surveillance and management of multidrug-resistant microorganisms

Multidrug-resistant organisms are an established and growing worldwide public health problem and few therapeutic options remain available. The traditional antimicrobials (glycopeptides) for multidrug-resistant Gram-positive infections are declining in efficacy. New drugs that are presently available are linezolid, daptomicin and tigecycline, which have well-defined indications for severe infections, and talavancin, which is under Phase III trial for hospital-acquired pneumonia. Unfortunately the therapies available for multidrug-resistant Gram-negatives, including carbapenem-resistant Pseudomonas aeruginosa, Acinetobacter baumannii and Enterobacteriaceae, are limited to only colistin and tigecycline. Both of these drugs are still not registered for severe infections, such as hospital acquired pneumonia. Consequently, as confirmed by scientific evidence, a multidisciplinary approach is needed. Surveillance, infection control procedures, isolation and antimicrobial stewardship should be implemented to reduce multidrug-resistant organism diffusion.

Diagnosis and management of prosthetic joint infection

PURPOSE OF REVIEW

Prosthetic joint infection remains a devastating complication of arthroplasty associated with significant patient morbidity. The demand for arthroplasty is rapidly growing with a corresponding increase in the number of infections involving the prosthesis. The diagnosis and treatment of prosthetic joint infections presents a significant challenge to orthopaedic and infectious diseases clinicians.

RECENT FINDINGS

The underlying pathogenesis of prosthetic joint infections is due to the ability of the microorganisms to form a biofilm. The biofilm provides protection against host immune responses and antimicrobial therapy. In addition, it impedes standard laboratory diagnostic techniques. This review will examine new investigations to improve the diagnostic yield and rapidity of diagnosis of infections, including the use of sonication to disrupt the biofilm, new molecular tests to improve the detection of infecting microorganisms and new imaging techniques such as (18)F-fluoro-deoxyglucose PET.

SUMMARY

The successful treatment of prosthetic joint infections is dependent on eliminating the biofilm dwelling microorganisms whilst maintaining patient mobility and quality of life. This review will examine current understanding of management approaches for these infections, with a particular focus on antimicrobial therapy with activity against the biofilm, such as rifampicin and fluoroquinolones.

Preliminary evaluation of technetium-99m-labeled ceftriaxone: infection imaging agent for the clinical diagnosis of orthopedic infection

OBJECTIVE

In this study we sought to assess the efficacy of a technetium-99m (Tc-99m)-labeled third-generation cephalosporin as an infection imaging agent in the accurate detection of the sites of bacterial infection in vivo.

DESIGN

Ceftriaxone (CRO) was formulated into a ready-to-use single-vial cold kit with a shelf-life of over 6 months and was successfully labeled with technetium. The radiolabeled drug, Tc-99m-CRO, was subjected to the following preclinical evaluations: radiochemical purity, in vitro and in vivo stability, bacterial binding assay, and pharmacokinetic studies in animals and in human patients.

RESULTS

The kit formulation exhibited excellent radiolabeling efficiency (∼99%) and high in vitro and in vivo stability. The radiolabeled drug exhibited slow blood clearance (12% at 4 h), and the high protein binding and excretion pattern of the labeled formulation mimics the reported pharmacokinetic profile of the drug alone. In the animal model, scintigraphy scans showed higher uptake of the radiopharmaceutical in infectious lesions, even at 1 h post-administration, in comparison to inflammatory lesions. The clinical evaluation of Tc-99m-labeled CRO showed a diagnostic accuracy of 83.3%, and a sensitivity and specificity of 85.2% and 77.8%, respectively.

CONCLUSIONS

This kit formulation has the potential for imaging bacterial infections with much higher sensitivity and specificity as compared to other Tc-99m-labeled antibiotics available as convenient ready-to-use kits in routine clinical practice.

Characteristics and outcome of 16 periprosthetic shoulder joint infections

PURPOSE

Shoulder arthroplasties are increasingly performed, but data on periprosthetic joint infections (PJI) in this anatomical position are limited. We retrospectively investigated the characteristics and outcome of shoulder PJI after primary arthroplasty from 1998 to 2010 in a single centre.

METHODS

Periprosthetic joint infection was defined as periprosthetic purulence, presence of sinus tract or microbial growth. A Kaplan-Meier survival method was used to estimate relapse-free survival of prosthesis.

RESULTS

From 1,571 primary shoulder prostheses, we evaluated 16 patients with a PJI at different stages, i.e, early (n = 4), delayed (n = 6) and late (n = 6) infections. The median patient age was 67 (range 53-86) years, and 69 % were females. The most commonly isolated microorganism was Propionibacterium acnes in 38 % of patients (monobacterial in four and polymicrobial in two patients). In 14 of the 16 patients, surgical interventions consisting of debridement and implant retention (6 patients), exchange (7) and explantation (1) were performed. Four patients had a relapse of infection with P. acnes (n = 3) or Bacteroides fragilis (n = 1). The relapse-free survival of the prosthesis was 75 % (95 % confidence interval 46-90 %) after 1 and 2 years, 100 % in six patients following the treatment algorithm for hip and knee PJI and 60 % in 10 patients not followed up. All but one of the relapses were previously treated without exchange of the prosthesis.

CONCLUSIONS

As recommended for hip and knee PJI, we suggest treating shoulder PJI with a low-grade infection by microorganisms such as P. acnes with an exchange of the prosthesis. Cohort studies are needed to verify our results.