Diagnosis and management of prosthetic joint infection

Comprehensive analysis of the pathogen spectrum and antibiotic resistance profiles in periprosthetic joint infections: a single center retrospective study

Objective

The objective of this study was to preliminarily examine the demographic profiles, the spectrum of pathogenic bacteria, and the antibiotic resistance patterns among patients with periprosthetic joint infection (PJI), while also offering deeper insights into the microbiological characteristics specifically in diabetic patients with PJI.

Methods

A retrospective analysis of 278 patients diagnosed with PJI from January 2019 to December 2024 at our institution was performed. Demographic characteristics of the patients, the distribution of pathogenic bacteria, and data on antibiotic resistance were statistically analyzed employing the chi-square test and t-test.

Results

Gram-positive cocci comprised 56.6% of all pathogenic bacteria, whereas coagulase-negative staphylococci constituted 28.1% of the total. Throughout the study period, a significant decrease was observed in the proportion of rifampicin-resistant coagulase-negative staphylococci (CoNS), from 27.0% to 10.4%. Similarly, a marked decline was noted in the proportion of gentamicin-resistant Staphylococcus aureus, from 50.0% to 15.4%. Conversely, there was a dramatic increase in the proportion of amoxicillin-clavulanate-resistant gram-negative bacilli, from 23.1% to 64.7%. The incidence of fungal infections was notably higher among diabetic patients with PJI compared to their non-diabetic counterparts.

Conclusion

This study demonstrates that the distribution pattern of pathogenic bacteria and their antibiotic resistance profiles among patients with PJI undergoes continuous variation. Moreover, there exist significant differences in the distribution of pathogenic bacteria between those with diabetes and those without diabetes among PJI patients. This serves as a crucial theoretical foundation and empirical support for the rigorous and tailored development of anti-infective treatment strategies for patients with various types of PJI.

Intranasal Testing and Treatment for Staphylococcus aureus With Intravenous Vancomycin and Intranasal Povidone-iodine Prior to Posterior Spinal Fusion: A Retrospective Cohort Study Between Two High-volume Children's Hospitals

Background

The impact of surgical site infections in spinal surgery can be profound. Several studies have demonstrated that S. aureus carriers have an increased risk of surgical site infection (SSI). The current literature shows decreased SSI in the adult population with povidine-iodine (PI) nasal treatment for decolonizing the nares of patients infected with S. aureus. The goal of this research study was to analyze the isolated effect of presurgical S. aureus nasal testing and PI application prior to spinal surgery.

Methods

This is a retrospective cohort study of children 8 to 18 years of age who underwent posterior spinal fusion from 2018 to 2020 at two standalone academic pediatric hospitals. Both hospitals had the same preoperative surgical bundle except that Group B included testing for S. aureus and treatment preoperatively if positive. In addition, all patients in Group B received PI nasal decolonization on the day of surgery.

Results

The overall infection rate between both hospitals was identified as 3.4%, with no difference between the two groups. The infection rate was lowest for adolescent idiopathic scoliosis, with a rate of 1.3% and highest for neuromuscular scoliosis, with a rate of 8.2%. Hospital-wide bacterial rates in Group A compared to Group B were higher for all S. aureus species (33.8% vs 30.1%, P ​= ​0.0004), methicillin-sensitive S. aureus (24.6% vs 13.1 %, P ​< ​0.001) but lower for methicillin-resistant S. aureus (9.2% vs 17%, P ​= ​0.02). Postoperative infection culture rates or bacterium types were not significantly different between the two groups.

Conclusions

The treatment of patients with PI nasal decolonization in the pediatric spinal fusion cohort did not show a decrease in postoperative infections. The PI nasal testing and treatment was $308.25 per patient and $189,580.75 over the study period. Elimination of intranasal testing and S. aureus treatment result in cost savings and eliminates an unpleasant patient experience.

Key Concepts

(1)The treatment of patients with povidine-iodine (PI) nasal decolonization in a pediatric spinal fusion cohort did not show a decrease in postoperative infections.(2)Elimination of intranasal testing and Staphylococcus aureus treatment in a pediatric spinal fusion cohort results in cost savings and reduces an unpleasant experience for the patient.(3)Increased surgical time during posterior spinal fusion in a pediatric cohort of patient did not lead to an increased rate of surgical site infection (SSI).(4)Across the cohort of pediatric patient undergoing posterior spinal fusion (PSF), the rate of infection for adolescent idiopathic scoliosis (AIS) patients was 1.3% compared with 8.2% infection rate in patients with neuromuscular scoliosis (NMS).

Level of Evidence

Level III.

Effects of an enhanced recovery after surgery nursing programme on surgical site wound infection and postoperative complications in patients undergoing total knee arthroplasty: A meta-analysis

This meta-analysis aimed to investigate the effects of the enhanced recovery after surgery (ERAS) nursing program on surgical wound infection (SWI) and postoperative complications in patients undergoing total knee arthroplasty (TKA). The PubMed, Web of Science, Cochrane Library, Embase, China National Knowledge Infrastructure and Wanfang databases were searched from the date of establishment of the database until August 2023 for randomised controlled trials (RCTs) that assessed the effects of the ERAS nursing program on SWI and postoperative complications in patients undergoing TKA. The literature was screened, data were extracted by two independent investigators, and the literature quality was assessed using the methods recommended by the Cochrane Collaboration. Data analysis was performed using Stata 17.0 software. Nineteen RCTs with 1580 patients were included in the study. The meta-analysis results showed that the rates of SWI (odds ratio [OR] = 0.19, 95% confidence interval [CI]: 0.10-0.37, p < 0.001) and postoperative complications (OR = 0.18, 95% CI: 0.12-0.25, p < 0.001) were significantly lower in the ERAS intervention group than those in the control group. Therefore, ERAS intervention after TKA can significantly reduce the occurrence of SWI and postoperative complications. It has a remarkable rehabilitation effect and can be widely used in clinical settings.

Development of droplet digital PCR-based detection of bacterial pathogens in prosthetic joint infection: a preliminary study using a synthesized model plasmid

Periprosthetic joint infection (PJI) can be diagnosed to characterize the microorganisms constituting a biofilm, which is an essential procedure for proper treatment. The gold standard method for detecting and identifying the causative microorganism is culture of microorganisms from patients-derived sample.; however, this method takes a long time and has low sensitivity. To compensate for these limitations, identification methods based on real-time PCR (RT-PCR) have been widely used. However, RT-PCR also has limitations, including low sensitivity and the requirement of a standard curve for quantification. Therefore, to prevent significant proliferation of pathogenic bacteria, it is important to detect a limited number of infectious bacteria during early stages of PJI. In the present study, we developed droplet digital PCR-based detection of bacterial pathogens in PJI. And we evaluated the analytical performance of the assay using a model plasmid, based on the 16S ribosomal DNA sequence of target bacteria commonly found in PJI. We also prepared genomic DNA extracted from E. coli, S. aureus, and S. epidermidis to test whether ddPCR provides better sensitivity and quantification of the target sequences. ddPCR detected 400 attograms of target DNA, which was more than 10 times less than that detected by real-time PCR using synthesized plasmid. In addition, ddPCR detected target regions from genomic DNA of 50 femtograms for E. coli, 70 femtograms for S. epidermidis, and 90 femtograms for S. aureus. The results indicate that ddPCR has the potential to decrease the microbial detection limit and provide precise detection, signifying its effectiveness for early PJI.

The role of WNT and IL-1 signaling in osteoarthritis: therapeutic implications for platelet-rich plasma therapy

Different from inflammatory arthritis, where biologicals and targeted synthetic molecules have revolutionized the disease course, no drug has demonstrated a disease modifying activity in osteoarthritis, which remains one of the most common causes of disability and chronic pain worldwide. The pharmacological therapy of osteoarthritis is mainly directed towards symptom and pain relief, and joint replacement is still the only curative strategy. Elucidating the disease pathophysiology is essential to understand which mechanisms can be targeted by innovative therapies. It has extensively been demonstrated that aberrant WNT and IL-1 signaling pathways are responsible for cartilage degeneration, impaired chondrocyte metabolism and differentiation, increased extracellular matrix degradation, and altered subchondral bone homeostasis. Platelet-rich plasma is an autologous blood derivative containing a concentration of platelets that is much higher than the whole blood counterpart and has shown promising results in the treatment of early knee osteoarthritis. Among the proposed mechanisms, the modulation of WNT and IL-1 pathways is of paramount importance and is herein reviewed in light of the proposed regenerative approaches.

C9 immunostaining as a tissue biomarker for periprosthetic joint infection diagnosis

Background

Culture-negative periprosthetic joint infections (PJI) are often false diagnosed as aseptic implant failure leading to unnecessary revision surgeries due to repeated infections. A marker to increase the security of e PJI diagnosis is therefore of great importance. The aim of this study was to test C9 immunostaining of periprosthetic tissue as a novel tissue-biomarker for a more reliable identification of PJI, as well as potential cross-reactivity.

Method

We included 98 patients in this study undergoing septic or aseptic revision surgeries. Standard microbiological diagnosis was performed in all cases for classification of patients. Serum parameters including C-reactive protein (CRP) serum levels and white blood cell (WBC) count were included, and the periprosthetic tissue was immunostained for C9 presence. The amount of C9 tissue staining was evaluated in septic versus aseptic tissue and the amount of C9 staining was correlated with the different pathogens causing the infection. To exclude cross-reactions between C9 immunostaining and other inflammatory joint conditions, we included tissue samples of a separate cohort with rheumatoid arthritis, wear particles and chondrocalcinosis.

Results

The microbiological diagnosis detected PJI in 58 patients; the remaining 40 patients were classified as aseptic. Serum CRP values were significantly increased in the PJI cohort. Serum WBC was not different between septic and aseptic cases. We found a significant increase in C9 immunostaining in the PJI periprosthetic tissue. To test the predictive value of C9 as biomarker for PJI we performed a ROC analyses. According to the Youden's criteria C9 is a very good biomarker for PJI detection with a sensitivity of 89% and a specificity of 75% and an AUC of 0.84. We did not observe a correlation of C9 staining with the pathogen causing the PJI. However, we observed a cross reactivity with the inflammatory joint disease like rheumatoid arthritis and different metal wear types. In addition, we did not observe a cross reactivity with chondrocalcinosis.

Conclusion

Our study identifies C9 as a potential tissue-biomarker for the identification of PJI using immunohistological staining of tissue biopsies. The use of C9 staining could help to reduce the number of false negative diagnoses of PJI.

Microbiological profiles and antibiotic resistance of periprosthetic joint infection after hip replacement in patients with fracture or non-fracture: A comparative study

BACKGROUND

Periprosthetic joint infection (PJI) is one of the worst complications following total joint arthroplasty (TJA). Unfortunately, effective prevention strategies to reduce the burden of PJI have not been fully determined in hip replacement patients with fracture and non-fracture.

OBJECTIVE

This study aimed to analyze and compare the demographic characteristics, microbiological profiles and antibiotic resistance of PJI after hip replacement between patients with fracture and non-fracture.

METHODS

We retrospectively analyzed the data of 132 patients who treated PJI. There were divided into two groups: non-fracture group (64 patients infected after hip replacement for fracture) and non-fracture group (68 patients infected after hip replacement for non-fracture). Microorganisms were obtained from the synovial fluid and infected necrotic tissue in the joint capsule, medullary cavity, or acetabulum in all patients, and microbiological profiles and antibiotic resistance were evaluated.

RESULTS

Coagulase-negative staphylococci (CoNS) were the most common pathogenic microorganisms in all patients. Methicillin-resistant Staphylococcus (MRS) accounted for 25% in all pathogenic microbes. Staphylococci showed high drug resistance rates to clindamycin, levofloxacin, and all of the first- and second-generation cephalosporins. MRS isolates in non-fracture group had higher drug resistance rates to clindamycin and levofloxacin than than those in fracture group. Gram-negative bacilli (GNB) showed high drug resistance rates to Aztreonam, gentamicin and all of the third- and fourth-generation cephalosporins. Furthermore, GNB isolates in the non-fracture group showed higher resistance rates to gentamicin and all of the third- and fourth-generation cephalosporins.

CONCLUSIONS

MRS isolates in the non-fracture group showed higher drug resistance rates to clindamycin and levofloxacin, and GNB isolates in non-fracture group showed higher drug resistance rates to gentamicin and all of the third- and fourth-generation cephalosporins.

The Ratio of IL-6 to IL-4 in Synovial Fluid of Knee or Hip Performances a Noteworthy Diagnostic Value in Prosthetic Joint Infection

The diagnosis of prosthetic joint infection (PJI) is still a challenge, the ratio of interleukin-6 (IL-6) to IL-4 in the joint fluid of knee or hip was used to analyze whether the diagnostic accuracy of PJI can be improved. Between January 2017 and May 2022, 180 patients who developed pain after revision total hip or knee arthroplasty were enrolled retrospectively. 92 patients of PJI and 88 of aseptic failure were included. PJI was as defined by the Musculoskeletal Infection Society (MSIS). The content of IL-6 and IL-4 in synovial fluid of knee or hip were measured, and the areas under the receiver operating characteristic curve (ROC) and IL-6/IL-4 curve were analyzed to obtain a better diagnostic effect. The area under the curve of IL-6/IL-4 in synovial fluid of knee or hip was 0.9623, which was more accurate than ESR 0.5994 and C-reactive protein 0.6720. The optimal threshold of IL-6/IL-4 ratio was 382.10. Its sensitivity and specificity were 81.32% and 98.86%, respectively. The positive predictive value for the diagnosis of PJI was 98.91%. This study showed that the level of IL-6/IL-4 in synovial fluid of knee or hip could further improve the diagnostic accuracy for PJI.

Molecular sequencing technologies in the diagnosis and management of prosthetic joint infections

INTRODUCTION

Prosthetic joint infections (PJIs) can be challenging to eradicate and have high morbidity and mortality. Current microbiology culture methods can be associated with a high false-negative rate of up to 50%. Early and accurate diagnosis is crucial for effective treatment, and negative results have been linked to a greater rate of reoperation.

AREAS COVERED

There has been increasing investigation of the use of next-generation sequencing (NGS) technology such as metagenomic shotgun sequencing to help identify causative organisms and decrease the uncertainty around culture-negative infections. The clinical importance of the organisms detected and their management, however, requires further study. The polymerase chain reaction (PCR) has shown promise, but in recent years multiple studies have reported similar or lower sensitivity for bacteria detection in PJIs when compared to traditional culture. Furthermore, issues such as high cost and complexity of sample preparation and data analysis are to be addressed before it can move further toward routine clinical practice.

EXPERT OPINION

Metagenomic NGS has shown results that inspire cautious optimism - both in culture-positive and culture-negative cases of joint infection. Refinement of technique could revolutionize the way PJIs are diagnosed, managed, and drastically improve outcomes from this currently devastating complication.

Trends in microbiological profiles and antibiotic resistance in periprosthetic joint infections

OBJECTIVE

This study examined the trends in demographics, the distribution of microorganisms, and antibiotic resistance in patients with periprosthetic joint infection (PJI).

METHODS

We conducted a retrospective study of 231 consecutive patients diagnosed with PJI in our hospital from January 2006 to December 2015 (93 and 138 patients diagnosed in 2006-2010 and 2011-2015, respectively). The linear-by-linear chi-squared test was used to assess the trends in demographics, the distribution of microorganisms, and antibiotic resistance.

RESULTS

Gram-positive cocci accounted for 63.9% of all pathogens, and coagulase-negative Staphylococcus (CoNS) accounted for 38.1% of all isolates. The proportion of isolates identified as methicillin-resistant CoNS significantly increased over the study period (39.0% vs. 61.8%). In addition, the proportions of levofloxacin-resistant CoNS (4.9% vs. 21.8%) and Staphylococcus aureus (6.3% vs. 45.0%) isolates significantly increased over the study period. By contrast, the proportions of penicillin-resistant CoNS (82.9% vs. 40.0%) and S. aureus (75.0% vs. 30.0%) isolates decreased over the study period.

CONCLUSION

Our research revealed changes in the distribution of microorganisms and antibiotic resistance profile of the pathogens responsible for PJI over time, which could complicate treatment. These findings may serve as a reference for strategies to prevent and empirically treat PJI in China.

Advantages of 16S rRNA PCR for the diagnosis of prosthetic joint infection

16S ribosomal RNA (rRNA) PCR has been reported to be an effective diagnostic means in patients with prosthetic joint infection (PJI). The aim of the present meta-analysis is to establish the overall diagnostic accuracy of the measurement of 16S rRNA PCR for diagnosing PJI. PubMed, Web of Science, Cochrane Library, EMBASE and Wiley Online Library were searched for studies on 16S rRNA PCR in the diagnosis of PJI. The search incorporated all literature published up until December 2018 and the QUADAS-2 checklist were used for quality assessment. The sensitivity, specificity and other measures of accuracy of 16S rRNA PCR in the diagnosis of PJI were pooled. Statistical analysis was performed by employing Meta-Disc 1.4 and Stata 12.0 software. A total of 15 studies met the inclusion criteria. The summary estimates for 16S rRNA PCR in the diagnosis of PJI in these studies were pooled: Sensitivity, 0.70 (95% CI, 0.67-0.73); specificity, 0.93 (95% CI, 0.91-0.94); positive likelihood ratio, 10.93 (95% CI, 5.55-21.51); negative likelihood ratio, 0.33 (95% CI, 0.28-0.40); diagnostic odds ratio, 41.77 (95% CI, 19.90-87.68); and the area under the curve, 0.89. Subgroup analysis showed that the use of sonicate fluid and periprosthetic tissue has higher sensitivity (0.76; 95% CI, 0.69-0.82; and 0.73; 95% CI, 0.68-0.78, respectively), specificity (0.93, 95% CI, 0.90-0.96; and 0.95; 95% CI, 0.90-0.98, respectively) and area under the curve (0.93 and 0.98, respectively). 16S rRNA PCR assay plays an important role in the diagnosis of PJI. The results of 16S rRNA PCR assays should be interpreted in parallel with clinical findings, the results of microbiological, and other laboratory tests.

Phenazine Antibiotic-Inspired Discovery of Bacterial Biofilm-Eradicating Agents

Bacterial biofilms are surface-attached communities of slow-growing and non-replicating persister cells that demonstrate high levels of antibiotic tolerance. Biofilms occur in nearly 80 % of infections and present unique challenges to our current arsenal of antibiotic therapies, all of which were initially discovered for their abilities to target rapidly dividing, free-floating planktonic bacteria. Bacterial biofilms are credited as the underlying cause of chronic and recurring bacterial infections. Innovative approaches are required to identify new small molecules that operate through bacterial growth-independent mechanisms to effectively eradicate biofilms. One source of inspiration comes from within the lungs of young cystic fibrosis (CF) patients, who often endure persistent Staphylococcus aureus infections. As these CF patients age, Pseudomonas aeruginosa co-infects the lungs and utilizes phenazine antibiotics to eradicate the established S. aureus infection. Our group has taken a special interest in this microbial competition strategy and we are investigating the potential of phenazine antibiotic-inspired compounds and synthetic analogues thereof to eradicate persistent bacterial biofilms. To discover new biofilm-eradicating agents, we have established an interdisciplinary research program involving synthetic medicinal chemistry, microbiology and molecular biology. From these efforts, we have identified a series of halogenated phenazines (HPs) that potently eradicate bacterial biofilms, and future work aims to translate these preliminary findings into ground-breaking clinical advances for the treatment of persistent biofilm infections.

Culture-negative periprosthetic joint infections

Culture-negative periprosthetic joint infections (CN-PJI) pose a significant challenge in terms of diagnosis and management. The reported incidence of CN-PJI is reported to be between 7% and 15%.

Fungi and mycobacterium are thought to be responsible for over 85% of such cases with more fastidious bacteria accounting for the rest.

With the advent of polymerase chain reaction, mass spectrometry and next generation sequencing, identifying the causative organism(s) may become easier but such techniques are not readily available and are very costly.

There are a number of more straightforward and relatively low-cost methods to help surgeons maximize the chances of diagnosing a PJI and identify the organisms responsible.

This review article summarizes the main diagnostic tests currently available as well as providing a simple diagnostic clinical algorithm for CN-PJI.

Cite this article: EFORT Open Rev 2019;4:585-594. DOI: 10.1302/2058-5241.4.180067

Rapid analysis of bacterial composition in prosthetic joint infection by 16S rRNA metagenomic sequencing

Objectives

Prosthetic joint infection (PJI) is the most common cause of arthroplasty failure. However, infection is often difficult to detect by conventional bacterial cultures, for which false-negative rates are 23% to 35%. In contrast, 16S rRNA metagenomics has been shown to quantitatively detect unculturable, unsuspected, and unviable pathogens. In this study, we investigated the use of 16S rRNA metagenomics for detection of bacterial pathogens in synovial fluid (SF) from patients with hip or knee PJI.

Methods

We analyzed the bacterial composition of 22 SF samples collected from 11 patients with PJIs (first- and second-stage surgery). The V3 and V4 region of bacteria was assessed by comparing the taxonomic distribution of the 16S rDNA amplicons with microbiome sequencing analysis. We also compared the results of bacterial detection from different methods including 16S metagenomics, traditional cultures, and targeted Sanger sequencing.

Results

Polymicrobial infections were not only detected, but also characterized at different timepoints corresponding to first- and second-stage exchange arthroplasty. Similar taxonomic distributions were obtained by matching sequence data against SILVA, Greengenes, and The National Center for Biotechnology Information (NCBI). All bacteria isolated from the traditional culture could be further identified by 16S metagenomics and targeted Sanger sequencing.

Conclusion

The data highlight 16S rRNA metagenomics as a suitable and promising method to detect and identify infecting bacteria, most of which may be uncultivable. Importantly, the method dramatically reduces turnaround time to two days rather than approximately one week for conventional cultures.

Cite this article: M-F. Chen, C-H. Chang, C. Chiang-Ni, P-H. Hsieh, H-N. Shih, S. W. N. Ueng, Y. Chang. Rapid analysis of bacterial composition in prosthetic joint infection by 16S rRNA metagenomic sequencing. Bone Joint Res 2019;8:367–377. DOI: 10.1302/2046-3758.88.BJR-2019-0003.R2.

Synovial fluid interleukin-16, interleukin-18, and CRELD2 as novel biomarkers of prosthetic joint infections

Objectives

Prosthetic joint infection (PJI) diagnosis is a major challenge in orthopaedics, and no reliable parameters have been established for accurate, preoperative predictions in the differential diagnosis of aseptic loosening or PJI. This study surveyed factors in synovial fluid (SF) for improving PJI diagnosis.

Methods

We enrolled 48 patients (including 39 PJI and nine aseptic loosening cases) who required knee/hip revision surgery between January 2016 and December 2017. The PJI diagnosis was established according to the Musculoskeletal Infection Society (MSIS) criteria. SF was used to survey factors by protein array and enzyme-linked immunosorbent assay to compare protein expression patterns in SF among three groups (aseptic loosening and first- and second-stage surgery). We compared routine clinical test data, such as C-reactive protein level and leucocyte number, with potential biomarker data to assess the diagnostic ability for PJI within the same patient groups.

Results

Cut-off values of 1473 pg/ml, 359 pg/ml, and 8.45 pg/ml were established for interleukin (IL)-16, IL-18, and cysteine-rich with EGF-like domains 2 (CRELD2), respectively. Receiver operating characteristic curve analysis showed that these factors exhibited an accuracy of 1 as predictors of PJI. These factors represent potential biomarkers for decisions associated with prosthesis reimplantation based on their ability to return to baseline values following the completion of debridement.

Conclusion

IL-16, IL-18, and CRELD2 were found to be potential biomarkers for PJI diagnosis, with SF tests outperforming blood tests in accuracy. These factors could be useful for assessing successful debridement based on their ability to return to baseline values following the completion of debridement.Cite this article: M-F. Chen, C-H. Chang, L-Y. Yang, P-H. Hsieh, H-N. Shih, S. W. N. Ueng, Y. Chang. Synovial fluid interleukin-16, interleukin-18, and CRELD2 as novel biomarkers of prosthetic joint infections. Bone Joint Res 2019;8:179-188. DOI: 10.1302/2046-3758.84.BJR-2018-0291.R1.

Polymerase Chain Reaction Assay Using the Restriction Fragment Length Polymorphism Technique in the Detection of Prosthetic Joint Infections: A Multi-Centered Study

BACKGROUND

PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) techniques have been used for the diagnosis of bacteria in some infections. In this study, we aimed to evaluate the diagnostic accuracy of PCR for the diagnosis of prosthetic joint infections (PJI) and to identify isolated microorganisms, using the RFLP method.

METHODS

During January 2015 to January 2018, patients who were suspected of having PJI after arthroplasty surgery or were candidates for revision surgery due to loosening of implant entered the study. Patients who had 1 major criterion or 3 minor criteria for PJI based on the Philadelphia Consensus Criteria (PCC) on Periprosthetic Joint Infection were considered as cases of PJI. Both culture results and PCR findings, were cross compared with results of the PCC (as the gold standard criteria).

RESULTS

Overall, 76 samples were included in the study. Mean (standard deviation) age of patients was 66.72 ± 11.82 years. Overall, 57.9% of patients were females. Prevalence of PJI was 50% based on the PCC. Sensitivity, specificity, positive predictive value, negative predictive value, and general efficacy of PCR for detection of PJI was 97.4%, 100%, 100%, 97.4%, and 98.7%, respectively. Sensitivity, specificity, positive predictive value, negative predictive value, and general efficacy of culture was 31.6%, 100%, 65.7%, 100%, and 59.4%, respectively. We isolated a broad range of bacteria using PCR-RFLP including Gram-positive cocci such as Staphylococcus sp., Streptococcus sp., and Enterococcus sp., and Gram-negative bacilli such as Enterobacteriaceae sp., Pseudomonas sp. Citrobacter sp., as well as Chlamydophila pneumonia, Stenotrophomonas maltophilia, Brucella melitensis, non-gonococcal Neisseria, Kingella kingae, Bacteroides ovatus, and Proteus mirabilis from PJI patients.

CONCLUSION

Inhere, for the first time, we showed that PCR-RFLP is a powerful tool for identifying the type of bacteria involved in PJI, and can be used for follow-up of patients suspected of PJI and those with a history of antibiotic use. PCR-RFLP may be able to substantially decrease detection time of PJI among PCR-based methods, while allowing more accurate identification of the bacteria involved.

Recent Evidence on Bioactive Glass Antimicrobial and Antibiofilm Activity: A Mini-Review

Bone defects caused by trauma or pathological events are major clinical and socioeconomic burdens. Thus, the efforts of regenerative medicine have been focused on the development of non-biodegradable materials resembling bone features. Consequently, the use of bioactive glass as a promising alternative to inert graft materials has been proposed. Bioactive glass is a synthetic silica-based material with excellent mechanical properties able to bond to the host bone tissue. Indeed, when immersed in physiological fluids, bioactive glass reacts, developing an apatite layer on the granule’s surface, playing a key role in the osteogenesis process. Moreover, the contact of bioactive glass with biological fluids results in the increase of osmotic pressure and pH due to the leaching of ions from granules’ surface, thus making the surrounding environment hostile to microbial growth. The bioactive glass antimicrobial activity is effective against a wide selection of aerobic and anaerobic bacteria, either in planktonic or sessile forms. Furthermore, bioglass is able to reduce pathogens’ biofilm production. For the aforementioned reasons, the use of bioactive glass might be a promising solution for the reconstruction of bone defects, as well as for the treatment and eradication of bone infections, characterized by bone necrosis and destruction of the bone structure.

Evaluation of the use of sonication of retrieved implants for the diagnosis of prosthetic joint infection in a routine setting

In order to evaluate the usefulness of sonication of retrieved implants for the diagnosis of prosthetic joint infection (PJI) in a large group of patients in a routine setting, we designed a 3-year retrospective study. Patients were classified into two groups: those meeting the clinical criteria of PJI and those that did not (control group). Two hundred patients and 276 samples were included. The types of infection were early (n = 44), delayed (n = 53), positive intraoperative cultures (n = 13) and late-acute (n = 8). The culture sensitivities of sonicate fluid, periprosthetic tissue, synovial fluid and combination of periprosthetic tissue and/or synovial fluid were 69.5, 52.8, 54.8 and 60.2%, respectively. The specificities were 97.6, 90.3, 93.0 and 89.9%, respectively. Sonicate fluid culture of implants was more sensitive than peri-implant tissue, synovial fluid and combination of periprosthetic tissue and/or synovial fluid for all infection types, though it was especially useful in delayed infection: 91.3% vs. 60.0% (p = 0.0015), 63.2% (p = 0.0005) and 66.7% (p = 0.0001), respectively. When sonicate fluid culture of implants was performed in addition to conventional cultures, the sensitivity increased significantly in total (from 60.2 to 77.1%) and delayed PJI (from 45.1 to 71.7%). On the other hand, for early PJI, sonicate fluid culture of prosthesis was not superior to conventional diagnostic methods.

Time trends in the aetiology of prosthetic joint infections: a multicentre cohort study

It is important to know the spectrum of the microbial aetiology of prosthetic joint infections (PJIs) to guide empiric treatment and establish antimicrobial prophylaxis in joint replacements. There are no available data based on large contemporary patient cohorts. We sought to characterize the causative pathogens of PJIs and to evaluate trends in the microbial aetiology. We hypothesized that the frequency of antimicrobial-resistant organisms in PJIs has increased in the recent years. We performed a cohort study in 19 hospitals in Spain, from 2003 to 2012. For each 2-year period (2003-2004 to 2011-2012), the incidence of microorganisms causing PJIs and multidrug-resistant bacteria was assessed. Temporal trends over the study period were evaluated. We included 2524 consecutive adult patients with a diagnosis of PJI. A microbiological diagnosis was obtained for 2288 cases (90.6%). Staphylococci were the most common cause of infection (1492, 65.2%). However, a statistically significant rising linear trend was observed for the proportion of infections caused by Gram-negative bacilli, mainly due to the increase in the last 2-year period (25% in 2003-2004, 33.3% in 2011-2012; p 0.024 for trend). No particular species contributed disproportionally to this overall increase. The percentage of multidrug-resistant bacteria PJIs increased from 9.3% in 2003-2004 to 15.8% in 2011-2012 (p 0.008), mainly because of the significant rise in multidrug-resistant Gram-negative bacilli (from 5.3% in 2003-2004 to 8.2% in 2011-2012; p 0.032). The observed trends have important implications for the management of PJIs and prophylaxis in joint replacements.

An Osteoconductive Antibiotic Bone Eluting Putty with a Custom Polymer Matrix

With the rising tide of antibiotic resistant bacteria, extending the longevity of the current antibiotic arsenal is becoming a necessity. Developing local, controlled release antibiotic strategies, particularly for difficult to penetrate tissues such as bone, may prove to be a better alternative. Previous efforts to develop an osteoconductive local antibiotic release device for bone were created as solid molded composites; however, intimate contact with host bone was found to be critical to support host bone regrowth; thus, an osteocondconductive antibiotic releasing bone void filling putty was developed. Furthermore, a controlled releasing polymer matrix was refined using pendant-functionalized diols to provide tailorable pharmacokinetics. In vitro pharmacokinetic and bioactivity profiles were compared for a putty formulation with an analogous composition as its molded counterpart as well as four new pendant-functionalized polymers. A best-fit analysis of polymer composition in either small cylindrical disks or larger spheres revealed that the new pendant-functionalized polymers appear to release vancomycin via both diffusion and erosion regardless of the geometry of the putty. In silico simulations, a valuable technique for diffusion mediated controlled release models, will be used to confirm and optimize this property.

Is Preoperative Nasal Povidone-Iodine as Efficient and Cost-Effective as Standard Methicillin-Resistant Staphylococcus aureus Screening Protocol in Total Joint Arthroplasty?

The purpose of this study was to compare nasal povidone-iodine swab for total joint arthroplasty patients to methicillin-resistant Staphylococcus aureus (MRSA) screening on the incidence of 90-day postoperative surgical site infections in total knee and hip arthroplasties as well as the cost-effectiveness. This is a single-center retrospective review of primary or revision total knee or hip arthroplasty patients. There were 849 patients screened for MRSA and 1004 patients in the nasal swab groups, both with an infection rate of 0.8%. The mean cost for the nasal swab was $27.21 (SD, 0), significantly different (P ≤ .01) than the mean cost for MRSA screens, $121.16 (SD, 26.18). There were significant cost savings with no difference in infection rates; therefore, nasal povidone-iodine swab antiseptic is financially and clinically successful.

Evaluation of a Genus- and Group-Specific Rapid PCR Assay Panel on Synovial Fluid for Diagnosis of Prosthetic Knee Infection

We evaluated a genus- and group-specific PCR assay panel using 284 prosthetic knee synovial fluid samples collected from patients presenting to our institution with implant failure. Using the Musculoskeletal Infection Society diagnostic criteria, 88 and 196 samples were classified as showing prosthetic joint infection (PJI) and aseptic failure (AF), respectively. Sensitivities of the synovial fluid PCR panel and culture were 55.6% and 76.1% (P ≤ 0.001), respectively, and specificities were 91.8% and 97.4% (P = 0.016), respectively. Among the 70 subjects who had received antibiotics within the month preceding synovial fluid aspiration (48 of whom had PJI), PCR panel and synovial fluid culture sensitivities were 64.5% and 85.4%, respectively (P < 0.0001). In this group, the PCR panel detected Staphylococcus aureus in two culture-negative PJI cases. Overall, the evaluated molecular diagnostic tool had low sensitivity when applied to synovial fluid.

Ultrasound-guided synovial biopsy

Ultrasound-guided needle biopsy of synovium is an increasingly performed procedure with a high diagnostic yield. In this review, we discuss the normal synovium, as well as the indications, technique, tissue handling and clinical applications of ultrasound-guided synovial biopsy.

Therapeutic cyclic lipopeptides mining from microbes: latest strides and hurdles

Infectious diseases impose serious public health burdens and often have devastating consequences. The cyclic lipopeptides elaborated by bacteria Bacillus, Paenibacillus, Pseudomonas, Streptomyces, Serratia, Propionibacterium and fungus Fusarium are very crucial in restraining the pathogens. Composed of a peptide and a fatty acyl moiety these amphiphilic metabolites exhibit broad spectrum antimicrobial effects. Among the plethora of cyclic lipopeptides, only selective few have emerged as robust antibiotics. For their functional vigor, polymyxin, daptomycin, surfactin, iturin, fengysin, paenibacterin and pseudofactin have been integrated in mainstream healthcare. Daptomycin has been a significant part of antimicrobial arsenal since the past decade. As the magnitude of drug resistance rises in unprecedented manner, the urgency of prospecting novel cyclic lipopeptides is being perceived. Intense research has revealed the implication of these bioactive compounds stretching beyond antibacterial and antifungal. Anticancer, immunomodulatory, prosthetic parts disinfection and vaccine adjuvancy are some of the validated prospects. This review discusses the emerging applications, mechanisms governing the biological actions, role of genomics in refining structure and function, semi-synthetic analog discovery, novel strain isolation, setbacks etc. Though its beyond the scope of the current topic, for holistic purpose, the role of lipopeptides in bioremediation and crop biotechnology has been briefly outlined. This updated critique is expected to galvanize innovations and diversify therapeutic recruitment of microbial lipopeptides.

Biofilms in periprosthetic orthopedic infections

As the number of total joint arthroplasty and internal fixation procedures continues to rise, the threat of infection following surgery has significant clinical implications. These infections may have highly morbid consequences to patients, who often endure additional surgeries and lengthy exposures to systemic antibiotics, neither of which are guaranteed to resolve the infection. Of particular concern is the threat of bacterial biofilm development, since biofilm-mediated infections are difficult to diagnose and effective treatments are lacking. Developing therapeutic strategies have targeted mechanisms of biofilm formation and the means by which these bacteria communicate with each other to take on specialized roles such as persister cells within the biofilm. In addition, prevention of infection through novel coatings for prostheses and the local delivery of high concentrations of antibiotics by absorbable carriers has shown promise in laboratory and animal studies. Biofilm development, especially in an arthoplasty environment, and future diagnostic and treatment options are discussed.

Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management

Staphylococcus aureus is a major human pathogen that causes a wide range of clinical infections. It is a leading cause of bacteremia and infective endocarditis as well as osteoarticular, skin and soft tissue, pleuropulmonary, and device-related infections. This review comprehensively covers the epidemiology, pathophysiology, clinical manifestations, and management of each of these clinical entities. The past 2 decades have witnessed two clear shifts in the epidemiology of S. aureus infections: first, a growing number of health care-associated infections, particularly seen in infective endocarditis and prosthetic device infections, and second, an epidemic of community-associated skin and soft tissue infections driven by strains with certain virulence factors and resistance to β-lactam antibiotics. In reviewing the literature to support management strategies for these clinical manifestations, we also highlight the paucity of high-quality evidence for many key clinical questions.

The Use of Vacuum-Assisted Closure and GranuFoam Silver® Dressing in the Management of Diabetic Foot Ulcer

PURPOSE

The aim of this retrospective study was to evaluate the efficacy of vacuum-assisted closure (VAC) and GranuFoam Silver® dressing (KCI, San Antonio, TX) compared with conventional GranuFoam® dressing in the management of diabetic foot ulcers.

PATIENTS AND METHODS

Twenty-one consecutive patients treated with conventional or silver-coated foam dressing were reviewed retrospectively. The wound duration was 6 mo. Group 1 (n=10) received conventional foam dressing (GranuFoam) and group 2 (n=11) received silver-coated foam dressing (GranuFoam Silver). The wound surface area, duration of treatment, bacteriology, and recurrence were compared between the groups. The mean age of the patients was 61.70±10.52 y in group 1 and 67.27±11.28 y in group 2.

RESULTS

In group 1, the average surface area of the wounds was 45.30±46.96 cm2 and 18.40±23.48 cm2 in the pre-treatment and post-treatment periods, respectively. There was a statistically significant difference between two measurements (p=0.005). Average duration of the treatment was 25.50±27.13 d in this group. In group 2, average surface area of the wounds in the pre-treatment and post-treatment periods were 41.55±36.03 cm2 and 7.64±3.91 cm2, respectively. There was a statistically significant difference between two measurements (p=0.003). Average duration of the treatment was 10.09±3.51 d in this group. The patients treated with silver-impregnated polyurethane foam dressing had reduced recurrence (2 vs. 7 wounds, p=0.030) and increased number of the culture-negative cases at the end of the treatment.

CONCLUSION

With the results of the study, it was concluded that VAC GranuFoam silver dressing can be superior to conventional GranuFoam dressing in reducing the recurrence rate of infected diabetic foot ulcers.

In vitro antibiofilm activity of bioactive glass S53P4

AIM

This work aimed to investigate the ability of different formulations of bioactive glass (BAG)-S53P4 to interfere with bacterial biofilm produced on prosthetic material by methicillin-resistant Staphylococcus aureus and multi-drug-resistant Pseudomonas aeruginosa.

MATERIALS & METHODS

Antibiofilm activity of three formulations of bioglass was assessed at different time points through two different analyses: Crystal Violet and confocal laser scanning microscopy assays.

RESULTS

Significant differences in the whole biofilm were observed between BAG-S53P4-treated and control samples, while no marked changes in antibiofilm activity were observed among the tested formulations. Data from colorimetric assay were confirmed by confocal laser scanning microscopy analysis, which evidenced the significant reduction in biomass and a decrease of total cell volume when both S. aureus and P. aeruginosa biofilms were treated with BAG-S53P4.

CONCLUSION

BAG-S53P4 can be considered as an excellent adjuvant in the treatment of prosthetic infections related to biofilm.

[Microbiological diagnosis of periprosthetic joint infections]

BACKGROUND

Prosthetic joint infection is a rare but serious complication after arthroplasty, leading to prolonged hospitalization and repeated surgical intervention.

THEME

In this article, successful strategies for the rapid and accurate microbiological diagnosis of infection are reviewed. In the case of clinical suspicion of a prosthetic joint infection, at least a comprehensive clinical review of the patient's postoperative history, a physical examination, routine blood tests including white cell count, erythrocyte sedimentation rate, and C-reactive protein, and further investigation of the synovial-fluid leukocyte count and microbial culture are needed. Depending of the clinical signs of infection additional blood culture samples should be taken.

RESULTS

The gold standard to confirm infection is a surgical procedure with at least 5-6 biopsies from suspected areas for both microbial culture and histopathological examination. Culture results may be negative because of previous antimicrobial therapy, a low number of culturable organisms in biofilm formations, inappropriate culture medium, and prolonged transport time.

CONCLUSION

In any of these conditions, diagnosis with highly sensitive diagnostic techniques such as polymerase chain reaction should be considered for the identification of the causative agent in order to establish the most appropriate antimicrobial treatment options.

Is preoperative staphylococcal decolonization efficient in total joint arthroplasty

Intranasal carrier status of Methicillin-sensitive Staphylococcus aureus (MSSA), and Methicillin-resistant Staphylococcus aureus (MRSA) has been shown to be a significant risk factor for developing surgical site infections. To determine if current treatment protocol for positive nasal screen was effective at decolonizing carriers 289 consecutive patients undergoing primary or revision total joint arthroplasty were screened preoperatively. Those patients with positive cultures were treated with a 5-day course of intranasal mupirocin. Preoperatively 44 (15.2%) patients tested positive for MSSA colonization, and 12 (4.2%) patients for MRSA. Testing on the day of surgery revealed 15 (5.2%) patients with MSSA positive cultures, and 1 (0.35%) patient with a MRSA positive culture. Reduction of MSSA and MRSA colonization was statistically significant (P=0.0341, P=0.0073 respectively). Our overall results indicate that our current decolonization protocol with nasal mupirocin was effective in reducing MSSA and MRSA colonization, although a significant number of patients remained positive for MSSA.

Lavage with allicin in combination with vancomycin inhibits biofilm formation by Staphylococcus epidermidis in a rabbit model of prosthetic joint infection

BACKGROUND AND AIM

The present anti-infection strategy for prosthetic joint infections (PJI) includes the use of antibiotics and surgical treatments, but the bacterial eradication rates are still low. One of the major challenges is the formation of biofilm causing poor bacterial eradication. Recently it has been reported that allicin (diallyl thiosulphinate), an antibacterial principle of garlic, can inhibit bacteria adherence and prevent biofilm formation in vitro. However, whether allicin could inhibit biofilm formation in vivo is unknown. The aim of this study was to investigate the effects of allicin on biofilm formation, and whether allicin could potentiate the bactericidal effect of vancomycin in a rabbit PJI model.

METHODS

A sterile stainless-steel screw with a sterile ultra-high molecular weight polyethylene washer was inserted into the lateral femoral condyle of the right hind knee joint of rabbit, and 1 mL inoculum containing 104 colony-forming units of Staphylococcus epidermidis was inoculated into the knee joint (n = 32). Fourteen days later, rabbits randomly received one of the following 4 treatments using continuous lavages: normal saline, vancomycin (20 mcg/mL), allicin (4 mg/L), or allicin (4 mg/L) plus vancomycin (20 mcg/mL). Three days later, the washer surface biofilm formation was examined by scanning electron microscopy (SEM). The bacterial counts within the biofilm of implanted screws were determined by bacterial culture.

RESULTS

The lowest number of viable bacterial counts of Staphylococcus epidermidis recovered from the biofilm was in the rabbits treated with allicin plus vancomycin (P<0.01 vs. all other groups). The biofilm formation was significantly reduced or undetectable by SEM in rabbits receiving allicin or allicin plus vancomycin.

CONCLUSION

Intra-articular allicincan inhibit biofilm formation and enhance the bactericidal effect of vancomycin on implant surface in vivo. Allicin in combination with vancomycin may be a useful anti-infection strategy for the treatment of PJI.

The expanding horizon of prosthetic joint infections

Prosthetic joint infection (PJI) is a serious and potentially devastating complication of arthroplasty. Prior arthroplasty, immunosuppression, severe comorbid conditions, and prolonged surgical duration are important risk factors for PJI. More than half of the cases of PJI are caused by Staphylococcus aureus and coagulase-negative staphylococci. The biofilm plays a central role in its pathogenesis. The diagnosis of PJI requires the presence of purulence, sinus tract, evidence of inflammation on histopathology, or positive microbiologic cultures. The use of diagnostic imaging techniques is generally limited but may be helpful in selected cases. The most effective way to prevent PJI is to optimize the health of patients, using antibiotic prophylaxis in a proper and timely fashion. Management of PJI frequently requires removal of all hardware and administration of intravenous antibiotics. This review summarizes and analyzes the results of previous reports of PJI and assesses the prevention and management of this important entity.

Infection risk after orthopedic surgery in patients with inflammatory rheumatic diseases treated with immunosuppressive drugs

OBJECTIVE

The influence of specific medications on the risk of postoperative infection in patients with rheumatoid arthritis and other inflammatory rheumatic diseases (IRDs) remains unclear. This retrospective study examined the risk of postoperative infection at the site of surgery in patients treated with immunosuppressive drugs (including biologic agents) undergoing different types of orthopedic surgery.

METHODS

The study included 50,359 cases of orthopedic surgery performed in our hospital between 2000 and 2008. The primary outcome was operation-related infection. IRD patients were compared with those with degenerative or posttraumatic disorders, and in IRD patients, the effect of immunosuppressive medication, specifically tumor necrosis factor α (TNFα) inhibitors and their preoperative management, was examined.

RESULTS

There were 373 operation-related infections (0.8%) of 47,887 cases in the degenerative/posttraumatic group and 49 (2.0%) of 2,472 in the IRD group (higher infection rate in the IRD group; odds ratio [OR] 2.58 [95% confidence interval (95% CI) 1.91-3.48], P < 0.001). In the IRD group, elbow and foot surgery had the highest infection rates. The risk of infection was significantly increased in patients taking multiple conventional disease-modifying antirheumatic drugs (DMARDs; OR 2.49 [95% CI 1.06-5.84], P = 0.036) or TNFα inhibitors (OR 2.54 [95% CI 1.08-5.97], P = 0.032). The risk was especially high (6 [12%] of 49) if the last dose of TNFα inhibitor was given <1 administration interval before surgery.

CONCLUSION

The risk of postoperative infection was elevated in patients with IRDs, especially those taking >1 conventional DMARD or TNFα inhibitors. It may be advisable to consider stopping TNFα inhibitors ≥1 administration interval before surgery, since the risk of postoperative infection appears to be higher if the operation occurs within this period.

Conventional and molecular diagnostic strategies for prosthetic joint infections

An accurate diagnosis of prosthetic joint infection (PJI) is the mainstay for an optimized clinical management. This review analyzes different diagnostic strategies of PJI, with special emphasis on molecular diagnostic tools and their current and future applications. Until now, the culture of periprosthetic tissues has been considered the gold standard for the diagnosis of PJI. However, sonication of the implant increases the sensitivity of those cultures and is being increasingly adopted by many centers. Molecular diagnostic methods compared with intraoperative tissue culture, especially if combined with sonication, have a higher sensitivity, a faster turnaround time and are not influenced by previous antimicrobial therapy. However, they still lack a system for detection of antimicrobial susceptibility, which is crucial for an optimized and less toxic therapy of PJI. More studies are needed to assess the clinical value of these methods and their cost-effectiveness.

Antibacterial potency of V.A.C. GranuFoam Silver(®) Dressing

INTRODUCTION

V.A.C.(®) GranuFoam™ therapy is regularly used in the surgical therapy of infected wounds and soft tissue injuries. Silver nanoparticles can destroy bacterial cell walls and inhibit enzymes for cell replication. Silver dressings are therefore successfully used for many indications in wound therapy. In this study, we investigated the antimicrobial potency of ionic silver released from the silver-coated V.A.C.(®) GranuFoam™ during vacuum therapy. Silver dressing was exposed to agar plates populated with bacteria to measure silver release.

MATERIALS AND METHODS

A total of 15 agar plates colonised with either Staphylococcus aureus populations or with Staphylococcus epidermidis, were loaded with V.A.C. GranuFoam Silver(®) Dressing polyurethane foam (KCI, San Antonio, Texas). Each of 13 pieces of silver-coated foam was applied to an agar plate. Two plates were loaded with conventional black foam without any coating. After connecting to a vacuum pump, the vacuum therapy of the 15 plates lasted 5 days. The zone of inhibition of bacterial growth around the foam was measured daily. Silver release was also determined as a function of time.

RESULTS

At each time point, there was evidence of silver in the agar independent of bacterial colonisation. The S. aureus agar showed a consecutive increase in silver concentration from baseline upon 48 h after exposure to the negative pressure of V.A.C. therapy. An increasing mean silver level after 48, 72 and 96 h was measured under V.A.C. therapy with a peak value after 120 h. In contrast, the results from the S. epidermidis plates did not follow a linear pattern. At the beginning of vacuum therapy, we documented a rise in silver concentration. After 48-96h, the silver levels fluctuated. A maximum zone of inhibition in both bacterial colonised plates (S. aureus and S. epidermidis) was found 39 h after the start of the V.A.C. GranuFoam Silver(®) therapy.

CONCLUSION

From our results, we confirmed the antimicrobial effect of the silver ions against S. aureus and S. epidermidis under continuous V.A.C. GranuFoam(®) Silver therapy with a negative pressure of 25 mmHg. Furthermore we could quantify the amounts of silver, which were released from the foam under negative pressure as a function of time.