An Enhanced Understanding of Culture-Negative Periprosthetic Joint Infection with Next-Generation Sequencing: A Multicenter Study

Commercial Synovial Antigen Testing is Inferior to Traditional Culture for the Diagnosis of Periprosthetic Joint Infection in Patients Undergoing Revision Total Knee Arthroplasty

BACKGROUND

Despite its limitations, a culture remains the "gold standard" for pathogen identification in patients who have periprosthetic joint infection (PJI). Recently, a synovial fluid antigen test has been introduced by a commercial entity. The purpose of this multicenter study was to determine the accuracy of the antigen test in the diagnosis of PJI.

METHODS

This retrospective study identified 613 patients undergoing revision total knee arthroplasty who had undergone preoperative synovial fluid analysis. A PJI was defined using the 2018 International Consensus Meeting (ICM) criteria. Patients who had an extended period (> 180 days) from aspiration to revision procedure (n = 62), those presenting within 90 days of their index arthroplasty procedure (n = 17), and patients who had an inconclusive ICM score (n = 8) were excluded. Using receiver operator characteristic curve analyses, we examined the utility of the microbial identification (MID) antigen test and any positive culture (either preoperative or intraoperative) in the diagnosis of PJI.

RESULTS

A total of 526 patients were included. Of these, 125 (23.8%) were ICM positive and 401 (76.2%) were ICM negative. Culture demonstrated an area under the curve (AUC) of 0.864, sensitivity of 75.2%, and specificity of 97.5%. On the other hand, the MID test exhibited an AUC of 0.802, sensitivity of 61.6%, and specificity of 98.8%. The AUC of culture was significantly higher than that of the MID test (P = .037). The MID test was positive in 41.9% of culture-negative PJI cases. We also observed a high rate of discordance (29.7%) when both culture and the MID test were positive in the ICM-positive group.

CONCLUSIONS

Synovial fluid antigen testing does not provide additional clinical benefit when compared to traditional cultures for the diagnosis of PJI. The antigen test had low sensitivity in the diagnosis of PJI and a relatively high rate of discordance with culture.

LEVEL OF EVIDENCE

Level III.

Prevalence and Impact of Unexpected Positive Intraoperative Cultures in Total Hip or Knee Revision Surgery

BACKGROUND

Our aim was to evaluate the prevalence and impact of unexpected positive intraoperative cultures (UPICs) on the outcome of presumed aseptic total knee and hip revision surgery.

METHODS

Data regarding patients who underwent elective total hip or knee revision surgery from January 2003 to July 2017 due to preoperatively presumed aseptic reasons was retrospectively reviewed. Partial revisions and patients who had follow-ups below 60 months were excluded from the study. In all surgeries, at least three intraoperative samples were taken for microbial culture. Failure was defined as the need for re-revision due to any cause at 5 years and/or the need for antibiotic suppressive therapy. Overall, 123 total hip and 431 total knee revisions were eligible for the study. All cases had at least a 5 year follow-up.

RESULTS

There were 420 cases (75.8%) that had all cultures negative, 108 (19.5%) had a single UPIC, and 26 (4.7%) had either ≥ 2 UPICs for the same microorganism or 1 UPIC for a virulent microorganism. This latter group was not associated with a significantly higher failure rate (2 of 26, 7.7%) compared to those in the aseptic group (54 of 528, 10.2%). Revisions performed within the first 24 months after primary implantation had a higher 5-year re-revision rate (19.3 versus 8.4%, P = 0.01), mainly attributable to aseptic causes.

CONCLUSION

Total hip and knee revisions with UPICs were not significantly associated with a higher re-revision risk at 5 years. Those revisions performed within the first 24 months after primary arthroplasty had a higher rate of any-cause failure.

An overview of the current diagnostic approach to Periprosthetic Joint Infections

The diagnosis of periprosthetic joint infections (PJI) presents a formidable challenge to orthopaedic surgeons due to its complex and diverse manifestations. Accurate diagnosis is of utmost importance, as even mild pain following joint replacement surgery may indicate PJI in the absence of a definitive gold standard diagnostic test. Numerous diagnostic modalities have been suggested in the literature, and international societies have continually updated diagnostic criteria for this debilitating complication. This review article aims to comprehensively examine the latest evidence-based approaches for diagnosing PJI. Through a thorough analysis of current literature, we explore promising diagnostic strategies that have demonstrated effectiveness in identifying PJI. These strategies encompass the utilization of laboratory markers, such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), alongside imaging techniques such as magnetic resonance imaging (MRI) and leukocyte scintigraphy. Additionally, we highlight the importance of synovial fluid analysis, including the potential role of alpha-defensin as a biomarker, and examine evolving international diagnostic criteria to standardize and improve diagnostic accuracy.

Operating Room Air May Harbor Pathogens: The Role of an Ultraviolet Air Filtration Unit

BACKGROUND

One important factor for the prevention of surgical site infections is ultraclean air in the operating room (OR). Still, the direct sterilization potential of most technologies, especially in a dynamic clinical setting, is not well understood. We aimed to determine and compare the microbial presence from the inlet and outlet flow of a filtration unit with crystalline ultraviolet-C (C-UVC) light.

METHODS

A prospective study was conducted at a single institution, where primary total joint arthroplasty and spine surgeries were performed. The OR was fitted with a positive ventilation system. In addition, a filtration unit with a C-UVC sterilizing light was placed in the OR. The inlet and outlet air flows were swabbed simultaneously and compared. Swabs were processed for culture and next-generation sequencing.

RESULTS

The mean length of the surgical procedures sampled was 68 ± 13 minutes. Overall, 19 out of 200 (9.5%) swabs isolated microorganisms. Inlet air swabs were positive at a higher rate (16 versus 3%; P < .01) compared to the outlet air swabs. A wide variety of Gram-positive, Gram-negative, and anaerobic bacteria were isolated, but fungi were only recovered from inlet air swabs. The detection of microorganisms was also higher when more door openings were performed (32.5 ± 7.1 versus 27.9 ± 5.6; P < .01).

CONCLUSIONS

Air swabs mainly isolated microorganisms from the inlet flow to the filtration unit with a C-UVC light. The sterilizing unit counteracted factors affecting the air quality in the OR, namely door openings, surgical personnel, and tissue combustion.

Investigation of the pathogen-specific antibody response in periprosthetic joint infection

PURPOSE

Periprosthetic joint infections (PJIs) are a very demanding complication of arthroplasty. Diagnosis of PJI and pathogen identification pose considerable challenges in clinical practice. We hypothesized that the pathogen-specific immune response to PJI reflects the infection process, provides clinically relevant information on disease course, and has the potential to further optimize antimicrobial therapy.

METHODS

We conducted a prospective matched cohort pilot study with 13 patients undergoing two-stage septic revision arthroplasty (PJI patients) between 06/2020 and 06/2021, as well as 11 control patients undergoing one-stage aseptic revision arthroplasty (Non-PJI patients). Pre-, intra- and postoperative serum samples were collected at standardized time points. We developed a custom Luminex®-based quantitative bead-based suspension array (Infection Array; IA), and used it for simultaneous measurement of antibody specificities against 32 pathogens commonly associated with PJI in 267 serum samples.

RESULTS

The IA was able to trace the dynamics of the pathogen-specific humoral immune response in all patients against PJI-related pathogens, prominently coagulase-negative staphylococci and streptococci. Pathogen-specific serum antibody titers declined in 62% of PJI patients over the course of treatment, while no changes in antibody titers were observed in 82% of Non-PJI patients during this study. Our serological data strongly suggested that antibody signatures reflect an immune response to microbial invasion.

CONCLUSION

Our results provide insights into the pathophysiology of PJI and information on the individual disease courses. The IA is therefore a promising and novel serological tool of high resolution for monitoring the immunoproteomic footprints of infectious pathogens in the course of PJI.

Characterizing the Native Microbiome Using Next-Generation Sequencing of Bilateral 'Aseptic' Knees

BACKGROUND

Next generation sequencing (NGS) has proven ability to identify organisms beyond those identified through traditional culture-based techniques in cases of suspected prosthetic joint infection. However, there is concern that some microorganisms identified may represent the natural joint microbiome rather than pathogenic agents. This work sought to evaluate the presence of microorganisms identified with NGS in bilateral native, presumed "aseptic" knees with osteoarthritis.

METHODS

There were 40 patients undergoing primary unilateral (30) or bilateral (10) total knee arthroplasty enrolled prospectively. During surgery, samples of fluid and tissue were obtained from operative knees, and joint fluid was obtained from nonoperative knees. Samples were sent for NGS analysis and processed according to manufacturer protocols. Patient age, body mass index, comorbidities, prior history of injections, and grade of arthritis were evaluated for association with positive NGS results.

RESULTS

There were 3 of 80 samples (3.8%) that demonstrated positive NGS. There were two of these that had multiple microorganisms identified (1 knee with 4 microorganisms; 1 knee with 2 microorganisms). An additional 2 samples had positive NGS results below the manufacturer's threshold for reporting. The most common organism identified was Cutibacterium acnes, present in 2 of the 3 positive samples. No patient baseline characteristics were associated with positive NGS results.

CONCLUSIONS

Some native knee joints with osteoarthritis have positive microorganisms identified with NGS. The presence of microorganisms in the native knee has important implications for better understanding the native joint microbiome as well as utilization of NGS in cases of suspected prosthetic joint infection.

Culture-negative periprosthetic joint infections: Do we have an issue?

Culture-negative periprosthetic joint infection (PJI) poses a significant challenge in clinical settings. The lack of information on causative organism(s) leads to uncertainties regarding the choice of antimicrobial treatment, which can potentially adversely influence the outcome. Recent advances in molecular-based diagnostic methods have the potential to address the difficulties associated with culture-negative PJIs. These technologies offer a solution to the existing clinical dilemma by providing identification of pathogens and guiding appropriate antimicrobial treatment. In this narrative review, we provide information regarding: 1) incidence and risk factors for culture-negative PJI; 2) the optimal antimicrobial therapy and duration of treatment for culture-negative PJI; 3) outcome comparison between culture-positive and culture-negative PJI; and 4) utilization of novel molecular diagnostic methods in culture-negative PJI, including pathogen identification, and the implementation of an antibiotic stewardship program.

Diagnostics in Late Periprosthetic Infections-Challenges and Solutions

The rising number of arthroplasties is combined with a rising number of periprosthetic joint infections, which leads to life-concerning consequences for the patients, including extended antibiotic treatment, further surgery and increased mortality. The heterogeneity of the symptoms and inflammatory response of the patients due to, e.g., age and comorbidities and the absence of a single diagnostic test with 100% accuracy make it very challenging to choose the right parameters to confirm or deny a periprosthetic joint infection and to establish a standardized definition. In recent years, additional diagnostic possibilities have emerged primarily through the increasing availability of new diagnostic methods, such as genetic techniques. The aim of the review is to provide an overview of the current state of knowledge about the various tests, including the latest developments. The combination of different tests increases the accuracy of the diagnosis. Each physician or clinical department must select the tests from the available methods that can be best implemented for them in organizational and technical terms. Serological parameters and the cultivation of the samples from aspiration or biopsy should be combined with additional synovial tests to create an accurate figure for the failure of the prosthesis, while imaging procedures are used to obtain additional information for the planned therapeutic procedure.

Exploring the impact of pathogenic microbiome in orthopedic diseases: machine learning and deep learning approaches

Osteoporosis, arthritis, and fractures are examples of orthopedic illnesses that not only significantly impair patients' quality of life but also complicate and raise the expense of therapy. It has been discovered in recent years that the pathophysiology of orthopedic disorders is significantly influenced by the microbiota. By employing machine learning and deep learning techniques to conduct a thorough analysis of the disease-causing microbiome, we can enhance our comprehension of the pathophysiology of many illnesses and expedite the creation of novel treatment approaches. Today's science is undergoing a revolution because to the introduction of machine learning and deep learning technologies, and the field of biomedical research is no exception. The genesis, course, and management of orthopedic disorders are significantly influenced by pathogenic microbes. Orthopedic infection diagnosis and treatment are made more difficult by the lengthy and imprecise nature of traditional microbial detection and characterization techniques. These cutting-edge analytical techniques are offering previously unheard-of insights into the intricate relationships between orthopedic health and pathogenic microbes, opening up previously unimaginable possibilities for illness diagnosis, treatment, and prevention. The goal of biomedical research has always been to improve diagnostic and treatment methods while also gaining a deeper knowledge of the processes behind the onset and development of disease. Although traditional biomedical research methodologies have demonstrated certain limits throughout time, they nevertheless rely heavily on experimental data and expertise. This is the area in which deep learning and machine learning approaches excel. The advancements in machine learning (ML) and deep learning (DL) methodologies have enabled us to examine vast quantities of data and unveil intricate connections between microorganisms and orthopedic disorders. The importance of ML and DL in detecting, categorizing, and forecasting harmful microorganisms in orthopedic infectious illnesses is reviewed in this work.

Suppressive Antibiotic Therapy After Debridement, Antibiotics, and Implant Retention is Well-Tolerated Without Inducing Resistance: A Multicenter Study

BACKGROUND

Suppressive antibiotic therapy (SAT) after total joint arthroplasty (TJA) debridement, antibiotics, and implant retention (DAIR) maximizes reoperation-free survival. We evaluated SAT after DAIR of acutely infected primary TJA regarding: 1) adverse drug reaction (ADR)/intolerance; 2) reoperation for infection; and 3) antibiotic resistance.

METHODS

Patients who underwent total knee arthroplasty (TKA) or total hip arthroplasty (THA) DAIR for acute periprosthetic joint infection at two academic medical centers from 2015 to 2020 were identified (n = 115). Data were collected on patient demographics, infecting organisms, antibiotics, ADR/intolerances, reoperations, and antibiotic resistances. Median SAT duration was 11 months. Stepwise multivariate logistic regressions were used to identify covariates significantly associated with outcomes of interest.

RESULTS

There were 11.1 and 16.3% of TKA and THA DAIR patients, respectively, who had ADR/intolerance to SAT. Patients prescribed trimethoprim/sulfamethoxazole (P = .0014) or combination antibiotic therapy (P = .0169) after TKA DAIR had increased risk of ADR/intolerance. There was no difference in reoperation-free survival between TKA (83.3%) and THA (65.1%) DAIR (P = .5900) at mean 2.8-year follow-up. Risk of reoperation for infection was higher among TKA Staphylococcus aureus infections (P = .0004) and lower with increased SAT duration (P < .0450). The optimal duration of SAT was nearly 2 years. No cases of antibiotic resistance developed due to SAT.

CONCLUSIONS

Consider SAT after TJA DAIR due to improved reoperation-free survival and favorable safety profile. Prolonged SAT did not induce antibiotic resistance. Use trimethoprim/sulfamethoxazole with caution because of the increased likelihood of ADR/intolerance.

LEVEL OF EVIDENCE

Therapeutic Level III.

Higher sensitivity and accuracy of synovial next-generation sequencing in comparison to culture in diagnosing periprosthetic joint infection: a systematic review and meta-analysis

PURPOSE

The purpose of this meta-analysis was to compare the diagnostic parameters of synovial next-generation sequencing (NGS) and cultures in diagnosing periprosthetic joint infections (PJI).

METHODS

PubMed, Web of Science, Cochrane, and Google Scholar were searched from inception until 8 Jan 2022 for literature investigating the role of NGS in comparison to culture in the diagnosis of PJI. The studies were included if they investigated the diagnostic value of culture and NGS in diagnosing PJIs against the Musculoskeletal Infection Society (MSIS) criteria. Diagnostic parameters, such as sensitivity, specificity, positive predictive value, negative predictive value, positive-likelihood ratio, negative-likelihood ratio, accuracy, and area under the curve (AUC), were calculated for the included studies to evaluate the performance of NGS in comparison to culture in PJI diagnosis.

RESULTS

The total number of the included patients was 341 from seven articles. The pooled sensitivity, specificity, and diagnostic odds ratio of NGS were 94% (95% CI 91-97%), 89% (95% CI 82-95%), and 138.5 (95% CI 49.1-390.5), respectively. NGS has positive- and negative-likelihood ratios of 7.9 (95% CI 3.99-15.6) and 0.1 (95% CI 0.0-0.1), respectively. On the other hand, the pooled sensitivity, specificity, and diagnostic odds ratio of culture were 70% (95% CI 61-79%), 94% (95% CI 88-98%), and 28.0 (95% CI 12.6-62.2), respectively. The SROC curve for NGS showed that the accuracy (AUC) was 91.9%, and that the positive and negative predictive values were 8.6 (95% CI 5.0-19.5) and 0.1 (95% CI 0.0-0.1), respectively. While, culture SROC curve demonstrated that the accuracy (AUC) was 80.5% and the positive- and negative-likelihood ratio were 12.1 (95% CI 4.5-49.6) and 0.3 (95% CI 0.2-0.4).

CONCLUSIONS

NGS has a potential role in diagnosing hip and knee PJIs due to its high sensitivity, specificity, and accuracy. However, the sensitivity and specificity reported by the studies varied according to the time of synovial sampling (preoperative, postoperative, or mixed).

Recent updates in the development of molecular assays for the rapid identification and susceptibility testing of MRSA

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of healthcare- and community-associated infections. Nasal carriage of MRSA is a risk factor for subsequent MRSA infections. Increased morbidity and mortality are associated with MRSA infections and screening and diagnostic tests for MRSA play an important role in clinical management.

AREAS COVERED

A literature search was conducted in PubMed and supplemented by citation searching. In this article, we provide a comprehensive review of molecular-based methods for MRSA screening and diagnostic tests including individual nucleic acid detection assays, syndromic panels, and sequencing technologies with a focus on their analytical performance.

EXPERT OPINION

Molecular based-assays for the detection of MRSA have improved in terms of accuracy and availability. Rapid turnaround enables earlier contact isolation and decolonization for MRSA. The availability of syndromic panel tests that include MRSA as a target has expanded from positive blood cultures to pneumonia and osteoarticular infections. Sequencing technologies allow detailed characterizations of novel methicillin-resistance mechanisms that can be incorporated into future assays. Next generation sequencing is capable of diagnosing MRSA infections that cannot be identified by conventional methods and metagenomic next-generation sequencing (mNGS) assays will likely move closer to implementation as front-line diagnostics in the near future.

Real-Life Experience and Diagnostic Utility of the BioFire Joint Infection PCR Panel in Bone and Joint Infections: Analysis of a Prospective Validation Study

INTRODUCTION

Microbiological diagnosis is central for adequate treatment of bone and joint infections. Culture-based methods have a limited diagnostic sensitivity and a long turnaround time (TAT). The objective of this study was to compare the diagnostic performance of BioFire Joint Infection Panel Investigational Use Only version (hereafter BioFire)-a sample-to-result multiplex PCR panel-with culture-based methods and 16S ribosomal RNA (rRNA) PCR and sequencing, when available.

METHODS

This study presents a retrospective analysis of a prospective validation study of the BioFire panel. Specimens were obtained from consecutive patients evaluated for suspected bone and joint infections and processed using culture, BioFire, and 16S rRNA PCR and sequencing. Final clinical diagnosis was used as the reference for definition of infection.

RESULTS

Samples, including synovial fluid, bone and periarticular tissue, were obtained from 57 patients, 39 of whom were finally diagnosed with a bone or joint infection. Cultures were positive in 27/39 infected patients and in 3/18 uninfected patients (sensitivity 69%, specificity 83%). BioFire was positive in 22/39 infected patients and in none of the uninfected patients (sensitivity 56%, specificity 100%). Sensitivity for PCR panel organisms was 92% (22/24) and sensitivity for organisms identified by any microbiological modality was 69% (22/32). Gram stain results were positive in 13/39 infected patients and in none of the uninfected patients (sensitivity 33%, specificity 100%). 16S rRNA was positive in 20/28 infected patients and in 0/12 uninfected patients (sensitivity 71%, specificity 100%). Net machine time for BioFire-1 h-was shorter than the mean TAT for Gram stain results, which was 4 h.

CONCLUSION

BioFire offered equivalent diagnostic performance with superior TAT for bone and joint infections, compared with conventional methods.

Debridement, Antibiotic Pearls, and Retention of the Implant (DAPRI) in the Treatment of Early Periprosthetic Joint Infections: A Consecutive Series

INTRODUCTION

Periprosthetic joint infections (PJI) represent a devastating consequence following total joint arthroplasty (TJA). In this study, the authors describe a modified surgical technique developed to enhance the classical irrigation and debridement procedure (DAIR) to improve the possibilities of retaining an acutely infected TJA.

MATERIALS AND METHODS

This technique, debridement antibiotic pearls and retention of the implant (DAPRI), aims to remove the intra-articular biofilm allowing a higher and prolonged local antibiotic concentration by using calcium sulphate antibiotic-added beads in a setting of acute (<4 weeks from symptoms onset) PJI with pathogen identification. The combination of three different surgical techniques (tumor-like synovectomy, argon beam/acetic acid application and chlorhexidine gluconate brushing) aims to remove the bacterial biofilm from the implant without explanting the original hardware.

RESULTS

In total, 62 patients met the acute infection criteria (<4 weeks of symptoms); there were 57 males and five females. The patients' average age at the time of treatment was 71 years (62-77) and the average BMI was 37 kg/m². The micro-organism, always identified through synovial fluid analysis (culture, multiplex PCR or Next Generation Sequencing), was an aerobic Gram + in 76% (S. Coag-Neg 41%; S. aureus 16%), Gram-in 10% (E. coli 4%) and anaerobic Gram + in 4%. The DAPRI treatment was performed at an average of 3 days from symptoms onset (1-7 days). All patients underwent a 12-week course of post-operative antibiotic therapy (6 weeks I.V. and 6 weeks oral). All patients were available at the 2-year minimum FU (24-84 months). A total of 48 (77.5%) patients were infection-free at the final FU, while 14 patients underwent 2-stage revision for PJI recurrence. In total, four patients (6.4%) had a prolonged drainage from the wound after placement of the calcium sulphate beads.

CONCLUSIONS

This study suggests that the DAPRI technique could represent a valid alternative to the classic DAIR procedure. The current authors do not recommend this procedure outside of the main inclusive criteria (acute scenario micro-organism identification).

Nationwide Results of Microorganism Antigen Testing as a Component of Preoperative Synovial Fluid Analysis

BACKGROUND

Antigen immunoassays to detect synovial fluid (SF) microorganisms have recently been made available for clinical use. The purpose of this study was to determine the sensitivity and specificity of an SF microorganism antigen immunoassay detection (MID) panel, evaluate the panel's capability to detect microorganisms in the setting of culture-negative periprosthetic joint infection (PJI), and determine diagnostic predictive values of the MID panel for PJI.

METHODS

This study included 67,441 SF samples obtained from a hip or knee arthroplasty, from 2,365 institutions across the United States, submitted to 1 laboratory for diagnostic testing. All data were prospectively compiled and then were analyzed retrospectively. Preoperative SF data were used to classify each specimen by the International Consensus Meeting (2018 ICM) definition of PJI: 49,991 were not infected, 5,071 were inconclusive, and 12,379 were infected. The MID panel, including immunoassay tests to detect Staphylococcus, Candida, and Enterococcus, was evaluated to determine its diagnostic performance.

RESULTS

The MID panel demonstrated a sensitivity of 94.2% for infected samples that yielded positive cultures for target microorganisms (Staphylococcus, Candida, or Enterococcus). Among infected samples yielding positive cultures for their respective microorganism, individual immunoassay test sensitivity was 93.0% for Staphylococcus, 92.3% for Candida, and 97.2% for Enterococcus. The specificity of the MID panel for samples that were not infected was 98.4%, yielding a false-positive rate of 1.6%. The MID panel detected microorganisms among 49.3% of SF culture-negative infected samples. For PJI as a diagnosis, the positive predictive value of the MID panel was 91.7% and the negative predictive value was 93.8%. Among MID-positive PJIs, 16.2% yielded a discordant cultured organism instead of that detected by the antigen test.

CONCLUSIONS

SF microorganism antigen testing provides a timely adjunct method to detect microorganisms in the preoperative SF aspirate, yielding a low false-positive rate and enabling the detection of a microorganism in nearly one-half of SF culture-negative PJIs.

LEVEL OF EVIDENCE

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

Advances in the Microbiological Diagnosis of Prosthetic Joint Infections

A significant number of prosthetic joint infections (PJI) are culture-negative and/or misinterpreted as aseptic failures in spite of the correct implementation of diagnostic culture techniques, such as tissue sample processing in a bead mill, prolonged incubation time, or sonication of removed implants. Misinterpretation may lead to unnecessary surgery and needless antimicrobial treatment. The diagnostic value of non-culture techniques has been investigated in synovial fluid, periprosthetic tissues, and sonication fluid. Different feasible improvements, such as real-time technology, automated systems and commercial kits are now available to support microbiologists. In this review, we describe non-culture techniques based on nucleic acid amplification and sequencing methods. Polymerase chain reaction (PCR) is a frequently used technique in most microbiology laboratories which allows the detection of a nucleic acid fragment by sequence amplification. Different PCR types can be used to diagnose PJI, each one requiring the selection of appropriate primers. Henceforward, thanks to the reduced cost of sequencing and the availability of next-generation sequencing (NGS), it will be possible to identify the whole pathogen genome sequence and, additionally, to detect all the pathogen sequences present in the joint. Although these new techniques have proved helpful, strict conditions need to be observed in order to detect fastidious microorganisms and rule out contaminants. Specialized microbiologists should assist clinicians in interpreting the result of the analyses at interdisciplinary meetings. New technologies will gradually be made available to improve the etiologic diagnoses of PJI, which will remain an important cornerstone of treatment. Strong collaboration among all specialists involved is essential for the correct diagnosis of PJI.

Application of metagenomic next-generation sequencing in the detection of pathogens in spinal infections

BACKGROUND CONTEXT

The precise diagnosis and treatment of spinal infections (SI) remains challenging for spine surgeons. Identifying the pathogens of SI through metagenomic next-generation sequencing (mNGS) may be a key approach to addressing this challenge.

PURPOSE

To evaluate the accuracy and applicability of mNGS in determining the etiology of SI.

STUDY DESIGN

Diagnostic test study.

PATIENT SAMPLE

Twenty-five patients who had a clinical suspicion of SI and underwent mNGS testing.

OUTCOME MEASURES

The specificity, sensitivity, and time cost of mNGS and bacterial culture were compared. Clinical outcomes were assessed using the numeric rating scale (NRS) score, Oswestry Disability Index (ODI), and the Japanese Orthopedic Association (JOA) score. Demographic data and laboratory results (blood cell count (WBC), erythrocyte sedimentation rate (ESR), neutrophil percentage (NEUT%), and C-reactive protein level (CRP) were also evaluated.

METHODS

In this retrospective study, samples were obtained from 25 eligible patients via surgery or CT-guided puncture and subjected to histopathological examination, bacterial culture, and mNGS. The sensitivity and specificity of the bacterial cultures and mNGS were calculated with respect to the histopathological results as a reference. Postoperative antibiotics or antituberculosis drugs were administered on the basis of mNGS results, combined with clinical manifestations, imaging examination, and histopathology. The changes of clinical outcomes and laboratory results after treatment were observed.

RESULTS

Of the 25 patients, 21 had a positive pathology, of which 10 showed a tuberculous pathology, and the remaining 11 showed a nontuberculous inflammatory pathology. The sensitivity of mNGS was higher than that of the bacterial culture. However, the difference in specificity between bacterial culture and mNGS was not significant. Moreover, the time needed to perform mNGS was significantly lower than that of bacterial culture and pathology. All patients were followed up for more than three months, and CRP and NEUT% significantly decreased by three months after treatment. There was no significant difference in WBC and ESR. The ODI, NRS and JOA scores were significantly improved after treatment.

CONCLUSION

Metagenomic next-generation sequencing technology can play an important role in the detection of pathogens in SI and should be further investigated and applied in future studies.

2022 American Association of Hip and Knee Surgeons Symposium: Periprosthetic Joint Infection

Periprosthetic joint infection (PJI) is the leading cause of failure in patients undergoing total joint arthroplasty. This article is a brief summary of a symposium on PJI that was presented at the annual AAHKS meeting. It will provide an overview of current technqiues in the prevention, diagnosis, and management of PJI. It will also highlight emerging technologies in this setting.

Imaging in Hip Arthroplasty Management Part 2: Postoperative Diagnostic Imaging Strategy

Hip arthroplasty (HA) is a frequently used procedure with high success rates, but 7% to 27% of the patients complain of persistent postsurgical pain 1 to 4 years post-operation. HA complications depend on the post-operative delay, the type of material used, the patient’s characteristics, and the surgical approach. Radiographs are still the first imaging modality used for routine follow-up, in asymptomatic and painful cases. CT and MRI used to suffer from metallic artifacts but are nowadays central in HA complications diagnosis, both having their advantages and drawbacks. Additionally, there is no consensus on the optimal imaging workup for HA complication diagnosis, which may have an impact on patient management. After a brief reminder about the different types of prostheses, this article reviews their normal and pathologic appearance, according to each imaging modality, keeping in mind that few abnormalities might be present, not anyone requiring treatment, depending on the clinical scenario. A diagnostic imaging workup is also discussed, to aid the therapist in his imaging studies prescription and the radiologist in their practical aspects.