Value of mNGS in sonication fluid for the diagnosis of periprosthetic joint infection

State-of-the-Art Metagenomic Sequencing and Its Role in the Diagnosis of Periprosthetic Joint Infections

Metagenomic next-generation sequencing (mNGS) is increasingly being recognized as a valuable diagnostic tool for periprosthetic joint infections (PJIs). This study reviews the diagnostic utility of mNGS, highlighting its improved sensitivity in detecting pathogens, particularly in culture-negative and polymicrobial infections. However, the clinical application of this method is hindered by challenges such as the prevalence of host DNA, the necessity for extensive bioinformatic analysis, and the potential for contamination, which can lead to misinterpretation of results. As mNGS continues to evolve, it holds significant potential to improve the management of PJI and enhance the application of precision medicine in orthopedic infections.

Higher diagnostic value of next-generation sequencing versus culture in periprosthetic joint infection: A systematic review and meta-analysis

BACKGROUND

The next-generation sequencing (NGS) has developed rapidly in the past decade and is becoming a promising diagnostic tool for periprosthetic infection (PJI). However, its diagnostic value for PJI is still uncertain. The purpose of this systematic review and meta-analysis was to evaluate the diagnostic value of NGS compared to culture.

METHODS

In this systematic review and meta-analysis, electronic databases including PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science and clinicaltrials.gov were searched for studies from inception to 12 November 2023. Diagnostic parameters, such as sensitivity, specificity, diagnostic odds ratio and area under the summary receiver-operating characteristic (SROC) curve (AUC), were calculated for the included studies. A systematic review and meta-analysis was performed.

RESULTS

A total of 22 studies with 2461 patients were included in our study. The pooled sensitivity, specificity and diagnostic odds ratio of NGS were 87% (95% confidence interval [CI]: 83-90), 94% (95% CI: 91-96) and 111 (95% CI: 70-177), respectively. On the other hand, the pooled sensitivity, specificity and diagnostic odds ratio of culture were 63% (95% CI: 58-67), 98% (95% CI: 96-99) and 93 (95% CI: 40-212), respectively. The SROC curve for NGS and culture showed that the AUCs are 0.96 (95% CI: 0.94-0.98) and 0.82 (95% CI: 0.79-0.86), respectively.

CONCLUSION

This systematic review and meta-analysis found NGS had higher sensitivity and diagnostic accuracy but slightly lower specificity than culture. Based on the pooled results, we suggested NGS may have the potential to be a new tool for the diagnosis of PJI.

LEVEL OF EVIDENCE

Level IV.

[Study on effectiveness of antibiotics guided by metagenomic next-generation sequencing to control infection after total knee arthroplasty]

Objective

To explore the clinical value of metagenomic next-generation sequencing (mNGS) in diagnosis and treatment of periprosthetic joint infection (PJI) after total knee arthroplasty (TKA).

Methods

Between April 2020 and March 2023, 10 patients with PJI after TKA were admitted. There were 3 males and 7 females with an average age of 69.9 years (range, 44-83 years). Infection occurred after 8-35 months of TKA (mean, 19.5 months). The duration of infection ranged from 16 to 128 days (mean, 37 days). The preoperative erythrocyte sedimentation rate (ESR) was 15-85 mm/1 h (mean, 50.2 mm/1 h). The C reactive protein (CRP) was 4.4-410.0 mg/L (mean, 192.8 mg/L). The white blood cell counting was (3.4-23.8)×10 9/L (mean, 12.3×10 9/L). The absolute value of neutrophils was (1.1-22.5)×10 9/L (mean, 9.2×10 9/L). After admission, the joint fluid was extracted for bacterial culture method and mNGS test, and sensitive antibiotics were chosen according to the results of the test, and the infection was controlled in combination with surgery.

Results

Seven cases (70%) were detected as positive by bacterial culture method, and 7 types of pathogenic bacteria were detected; the most common pathogenic bacterium was Streptococcus lactis arrestans. Ten cases (100%) were detected as positive by mNGS test, and 11 types of pathogenic bacteria were detected; the most common pathogenic bacterium was Propionibacterium acnes. The difference in the positive rate between the two methods was significant ( P=0.211). Three of the 7 patients who were positive for both the bacterial culture method and the mNGS test had the same results for the type of pathogenic bacteria, with a compliance rate of 42.86% (3/7). The testing time (from sample delivery to results) was (4.95±2.14) days for bacterial culture method and (1.60±0.52) days for mNGS test, and the difference was significant ( t=4.810, P<0.001). The corresponding sensitive antibiotic treatment was chosen according to the results of bacterial culture method and mNGS test. At 3 days after the one-stage operation, the CRP was 6.8-48.2 mg/L (mean, 23.6 mg/L); the ESR was 17-53 mm/1 h (mean, 35.5 mm/1 h); the white blood cell counting was (4.5-8.1)×10 9/L (mean, 6.1×10 9/L); the absolute value of neutrophils was (2.3-5.7)×10 9/L (mean, 4.1×10 9/L). All patients were followed up 12-39 months (mean, 23.5 months). One case had recurrence of infection at 6 months after operation, and the remaining 9 cases showed no signs of infection, with an infection control rate of 90%.

Conclusion

Compared with bacterial culture method, mNGS test can more rapidly and accurately detect pathogenic bacteria for PJI after TKA, which is important for guiding antibiotics combined with surgical treatment of PJI.

Detection value of third-generation sequencing to identify the pathogenic organisms in prosthetic joint infection

To compare the detection value of third-generation sequencing (TGS) with pathogenic microbial culture in prosthetic joint infection (PJI). Arthrocentesis was performed on 29 patients who underwent hip and knee revision surgeries. In the PJI group, TGS detected 85.71 % of positive cases, while pathogenic microbial culture detected only 42.85 %. TGS identified 17 different pathogenic microorganisms, including Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus lactis, and Mycobacterium tuberculosis complex. In the loosening group, TGS was positive in one patient, while microbial culture was negative in all cases. TGS showed higher sensitivity (85.71 % vs. 42.85 %), comparable specificity (93.33 % vs. 100 %), and similar positive predictive value (92.31 % vs. 100 %) compared to culture.However, TGS had a higher negative predictive value (87.5 % vs. 65.22 %).Additionally, TGS provided faster results (mean time 23.8±3.6 h) compared to microbial culture (mean time 108.0±9.4 h).These findings suggest that TGS holds promise for detecting pathogenic microorganisms in PJI and has potential for clinical application.

Improved cure rate of periprosthetic joint infection through targeted antibiotic therapy based on integrated pathogen diagnosis strategy

Objectives

This study aimed to determine whether combined of pathogen detection strategies, including specimen acquisition, culture conditions, and molecular diagnostics, can improve treatment outcomes in patients with periprosthetic joint infections (PJI).

Methods

This retrospective study included suspected PJI cases from three sequential stages at our institution: Stage A (July 2012 to June 2015), Stage B (July 2015 to June 2018), and Stage C (July 2018 to June 2021). Cases were categorized into PJI and aseptic failure (AF) groups based on European Bone and Joint Infection Society (EBJIS) criteria. Utilization of pathogen diagnostic strategies, pathogen detection rates, targeted antibiotic prescription rates, and treatment outcomes were analyzed and compared across the three stages.

Results

A total of 165 PJI cases and 38 AF cases were included in this study. With the progressive implementation of the three optimization approaches across stages A, B and C, pathogen detection rates exhibited a gradual increase (χ2 = 8.282, P=0.016). Similarly, utilization of targeted antibiotic therapy increased stepwise from 57.1% in Stage A, to 82.3% in Stage B, and to 84% in Stage C (χ2 = 9.515, P=0.009). The 2-year infection control rate exceeded 90% in both stages B and C, surpassing stage A (71.4%) (χ2 = 8.317, P=0.011). Combined application of all three optimized protocols yielded the highest sensitivity of 91.21% for pathogen detection, while retaining higher specificity of 92.11%.

Conclusion

The utilization of combined pathogen diagnostic strategies in PJI can increase pathogen detection rates, improve targeted antibiotic prescription, reduce the occurrence of antibiotic complications, and achieve better treatment outcomes.

Optimal selection of specimens for metagenomic next-generation sequencing in diagnosing periprosthetic joint infections

Objective

This study aimed to assess the diagnostic value of metagenomic next-generation sequencing (mNGS) across synovial fluid, prosthetic sonicate fluid, and periprosthetic tissues among patients with periprosthetic joint infection (PJI), intending to optimize specimen selection for mNGS in these patients.

Methods

This prospective study involved 61 patients undergoing revision arthroplasty between September 2021 and September 2022 at the First Affiliated Hospital of Zhengzhou University. Among them, 43 cases were diagnosed as PJI, and 18 as aseptic loosening (AL) based on the American Musculoskeletal Infection Society (MSIS) criteria. Preoperative or intraoperative synovial fluid, periprosthetic tissues, and prosthetic sonicate fluid were collected, each divided into two portions for mNGS and culture. Comparative analyses were conducted between the microbiological results and diagnostic efficacy derived from mNGS and culture tests. Furthermore, the variability in mNGS diagnostic efficacy for PJI across different specimen types was assessed.

Results

The sensitivity and specificity of mNGS diagnosis was 93% and 94.4% for all types of PJI specimens; the sensitivity and specificity of culture diagnosis was 72.1% and 100%, respectively. The diagnostic sensitivity of mNGS was significantly higher than that of culture (X2 = 6.541, P=0.011), with no statistically significant difference in specificity (X2 = 1.029, P=0.310). The sensitivity of the synovial fluid was 83.7% and the specificity was 94.4%; the sensitivity of the prosthetic sonicate fluid was 90.7% and the specificity was 94.4%; and the sensitivity of the periprosthetic tissue was 81.4% and the specificity was 100%. Notably, the mNGS of prosthetic sonicate fluid displayed a superior pathogen detection rate compared to other specimen types.

Conclusion

mNGS can function as a precise diagnostic tool for identifying pathogens in PJI patients using three types of specimens. Due to its superior ability in pathogen identification, prosthetic sonicate fluid can replace synovial fluid and periprosthetic tissue as the optimal sample choice for mNGS.

The Clinical Impact of Metagenomic Next-Generation Sequencing for the Diagnosis of Periprosthetic Joint Infection

Background

Synovial fluid metagenomic next-generation sequencing was introduced into the diagnosis of periprosthetic joint infection (PJI) in recent years. However, the clinical impact of mNGS remains unknown. Therefore, we performed a prospective cohort study to evaluate the clinical impact of mNGS for PJI diagnosis.

Materials and Methods

Between April 2019 and April 2021, a total of 201 patients with suspected PJI were recruited in a high-volume PJI revision center. All patients underwent joint aspiration before surgeries and the obtained synovial fluids were sent to tests for the diagnosis of PJI. Based on the clinical evaluation of these patients, the patients were categorized into three groups: Group A: the mNGS reports were not acted upon. Group B: mNGS confirmed the standard diagnostic tests of PJI and generated identical clinical impact compared to standard diagnostic tests. Group C: mNGS results guided clinical therapy. Then, the concordance between synovial mNGS and cultures was analyzed. After that, multivariate regressions were performed to explore the "targeted populations" of mNGS tests.

Results

A total of 107 patients were diagnosed with PJI based on the 2014 MSIS criteria and there were 33, 123, 45 patients in the group A, B, C respectively. The predictive factors of mNGS inducing clinical impact compared to standard diagnostic tests were negative culture results (adjusted OR: 5.88), previous history of joint infection (adjusted OR: 5.97), polymicrobial PJI revealed by culture (adjusted OR: 4.39) and PJI identified by MSIS criteria (adjusted OR: 17.06).

Conclusion

When standard diagnostic tests for PJI were performed, about 22% of synovial fluid mNGS tests can change the treatment protocols built on standard diagnostic tests and affect the clinical practice. Thus, the use of synovial fluid mNGS in some "target" populations is more valuable compared to others such as patients with previous joint infection, polymicrobial PJI, and culture-negative PJI.

Evidence Level

Level I.

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).

Comparison of microbial detection rates in microbial culture methods versus next-generation sequencing in patients with prosthetic joint infection: a systematic review and meta-analysis

BACKGROUND

Accurate diagnosis of prosthetic joint infection (PJI) enables early and effective treatment. However, there is currently no gold standard test for microbial detection of PJI and traditional synovial fluid culture is relatively insensitive. Recently, it has been reported that sonicating fluid culture and next-generation sequencing (NGS) improve microbial detection rates. Hence, we performed a systematic review and meta-analysis to compare microbial detection rates in microbial culture methods with and without sonication versus NGS.

METHODS

We systematically searched EMBASE, PubMed, Scopus, CINAHL, and Ichushi databases and other sources (previous reviews) until August 2022. We evaluated the detection rates of pathogens in NGS and microbial cultures using samples of synovial or sonicated fluid.

RESULTS

Of the 170 citations identified for screening, nine studies were included. Pooled analysis indicated that NGS had the highest detection rate among the microbial detection methods (NGS vs. sonicated, odds ratios [OR] 5.09, 95% confidential interval [CI] 1.67-15.50; NGS vs. synovial, OR 4.52, 95% CI 2.86-7.16). Sonicated fluid culture showed a higher detection rate than synovial fluid culture (OR 2.11, 95% CI 1.23-3.62).

CONCLUSION

NGS might be useful as a screening tool for culture-negative patients. In clinical settings, sonicated fluid culture is a practical method for diagnosing PJI.

Rapid Diagnostics of Joint Infections Using IS-Pro

Diagnosis of bone and joint infections (BJI) relies on microbiological culture which has a long turnaround time and is challenging for certain bacterial species. Rapid molecular methods may alleviate these obstacles. Here, we investigate the diagnostic performance of IS-pro, a broad-scope molecular technique that can detect and identify most bacteria to the species level. IS-pro additionally informs on the amount of human DNA present in a sample, as a measure of leukocyte levels. This test can be performed in 4 h with standard laboratory equipment. Residual material of 591 synovial fluid samples derived from native and prosthetic joints from patients suspected of joint infections that were sent for routine diagnostics was collected and subjected to the IS-pro test. Bacterial species identification as well as bacterial load and human DNA load outcomes of IS-pro were compared to those of culture. At sample level, percent positive agreement (PPA) between IS-pro and culture was 90.6% (95% CI 85.7- to 94%) and negative percent agreement (NPA) was 87.7% (95% CI 84.1 to 90.6%). At species level PPA was 80% (95% CI 74.3 to 84.7%). IS-pro yielded 83 extra bacterial detections over culture for which we found supporting evidence for true positivity in 40% of the extra detections. Missed detections by IS-pro were mostly related to common skin species in low abundance. Bacterial and human DNA signals measured by IS-pro were comparable to bacterial loads and leukocyte counts reported by routine diagnostics. We conclude that IS-pro showed an excellent performance for fast diagnostics of bacterial BJI.

Diagnostic Role of mNGS in Polymicrobial Periprosthetic Joint Infection

OBJECTIVES

The purpose of this study was to explore the clinical value of metagenomic next-generation sequencing (mNGS) in the diagnosis of polymicrobial periprosthetic joint infection (PJI).

METHODS

Patients with complete data who underwent surgery at our hospital between July 2017 and January 2021 for suspected periprosthetic joint infection (PJI), according to the 2018 ICE diagnostic criteria, were enrolled, and all patients underwent microbial culture and mNGS detection, which were performed on the BGISEQ-500 platform. Microbial cultures were performed on two samples of synovial fluid, six samples of tissue, and two samples of prosthetic sonicate fluid for each patient. The mNGS was performed on 10 tissues, 64 synovial fluid samples, and 17 prosthetic sonicate fluid samples. The results of mNGS testing were based on the interpretation of mNGS results in the previous literature and the assertions of microbiologists and orthopedic surgeons. The diagnostic efficacy of mNGS in polymicrobial PJI was assessed by comparing the results of conventional microbial cultures and mNGS.

RESULTS

A total of 91 patients were finally enrolled in this study. The sensitivity, specificity, and accuracy of conventional culture for the diagnosis of PJI were 71.0%, 95.4%, and 76.9%, respectively. The sensitivity, specificity, and accuracy of mNGS for the diagnosis of PJI were 91.3%, 86.3%, and 90.1%, respectively. The sensitivity, specificity, and accuracy of conventional culture for the diagnosis of polymicrobial PJI were 57.1%, 100%, and 91.3%, respectively. mNGS had a sensitivity, specificity, and accuracy of 85.7%, 60.0%, and 65.2%, respectively, for the diagnosis of polymicrobial PJI.

CONCLUSIONS

mNGS can improve the diagnosis efficiency of polymicrobial PJI, and the combination of culture and mNGS is a promising method to diagnose polymicrobial PJI.

Diagnostic Performance of Metagenomic Next⁃Generation Sequencing in the Diagnosis of Prosthetic Joint Infection Using Tissue Specimens

Purpose

The purpose of this study was to evaluate the ability of metagenomic next-generation sequencing (mNGS) diagnosing prosthetic joint infection (PJI) using tissue from hip/knee rapidly and precisely, especially in patients who had received antibiotic treatment within the preceding two weeks.

Methods

From May 2020 to March 2022, 52 cases with suspected PJI were enrolled. mNGS was performed on surgical tissue samples. The sensitivity and specificity of mNGS in diagnosis was evaluated using culture in conjunction with MSIS criteria. This study also looked at how antibiotic use affected culture and mNGS efficacy.

Results

According to MSIS criteria, 31 of the 44 cases had PJI, and 13 were classified in the aseptic loosening group. Sensitivity, specificity, positive/negative predictive value (PPV/NPV), positive/negative likelihood ratio (PLR/NLR), and area under the curve (AUC) of mNGS assay were 80.6% (71.9-91.8%), 84.6 (73.7-97.9%), 92.6 (84.2-98.7%), 64.7 (58.6-74.7%), 5.241 (4.081-6.693), 0.229 (0.108-0.482) and 0.826 (0.786-0.967), respectively, with MSIS as a reference. When MSIS was used as a reference, the results of culture assay were 45.2% (40.8-51.5%), 100 (100.0-100.0%), 100 (100.0-100.0%), 43.3 (39.1-49.5%), +∞, 0.548 (0.396-0.617) and 0.726 (0.621-0.864), respectively. The AUC values for mNGS and culture were 0.826 and 0.731, respectively, and the differences were insignificant. mNGS demonstrated higher sensitivity than culture in PJI subjects who had previously received antibiotic treatment within 2 weeks (69.5% vs 23.1%, P = 0.03).

Conclusion

In our series, mNGS yield a higher sensitivity for diagnosis and pathogen detection of PJI compared to microbiological culture. Additionally, mNGS is less affected by prior antibiotic exposure.

The Effectiveness of Metagenomic Next-Generation Sequencing in the Diagnosis of Prosthetic Joint Infection: A Systematic Review and Meta-Analysis

Background

A prosthetic joint infection (PJI) is a devastating complication following total joint arthroplasties with poor prognosis. Identifying an accurate and prompt diagnostic method is particularly important for PJI. Recently, the diagnostic value of metagenomic next-generation sequencing (mNGS) in detecting PJI has attracted much attention, while the evidence of its accuracy is quite limited. Thus, this study aimed to evaluate the accuracy of mNGS for the diagnosis of PJI.

Methods

We summarized published studies to identify the potential diagnostic value of mNGS for PJI patients by searching online databases using keywords such as “prosthetic joint infection”, “PJI”, and “metagenomic sequencing”. Ten of 380 studies with 955 patients in total were included. The included studies provided sufficient data for the completion of 2-by-2 tables. We calculated the sensitivity, specificity, and area under the SROC curve (AUC) to evaluate mNGS for PJI diagnosis.

Results

We found that the pooled diagnostic sensitivity and specificity of mNGS for PJI were 0.93 (95% CI, 0.83 to 0.97) and 0.95 (95% CI, 0.92 to 0.97), respectively. Positive and negative likelihood ratios were 18.3 (95% CI, 10.9 to 30.6) and 0.07 (95% CI, 0.03 to 0.18), respectively. The area under the curve was 0.96 (95% CI, 0.93 to 0.97).

Conclusion

Metagenomic next-generation sequencing displays high accuracy in the diagnosis of PJI, especially for culture-negative cases.

Value of metagenomic next-generation sequencing in children with severe infectious diseases

OBJECTIVES

To study the application value of metagenomic next-generation sequencing (mNGS) in children with severe infectious diseases.

METHODS

An analysis was performed on the clinical data and laboratory test results of 29 children with severe infection who were admitted to the Second Affiliated Hospital of Wenzhou Medical University from June 2018 to December 2020. Conventional pathogen culture was performed for the 29 specimens (27 peripheral blood specimens and 2 pleural effusion specimens) from the 29 children, and mNGS pathogen detection was performed at the same time.

RESULTS

Among the 29 children, 2 tested positive by conventional pathogen culture with 2 strains of pathogen, and the detection rate was 7% (2/29); however, 20 children tested positive by mNGS with 38 strains of pathogen, and the detection rate was 69% (20/29). The pathogen detection rate of mNGS was significantly higher than that of conventional pathogen culture (P<0.05), and mNGS could detect the viruses, fungi, and other special pathogens that conventional pathogen culture failed to detect, such as Orientia tsutsugamushi. The univariate analysis showed that gender, routine blood test results, C-reactive protein, procalcitonin, D-dimer, radiological findings, and whether antibiotics were used before admission did not affect the results of mNGS (P>0.05).

CONCLUSIONS

Compared with conventional pathogen culture, mNGS is more sensitive for pathogen detection, with fewer interference factors. Therefore, it is a better pathogenic diagnosis method for severe infectious diseases in children.

Shotgun-metagenomics based prediction of antibiotic resistance and virulence determinants in Staphylococcus aureus from periprosthetic tissue on blood culture bottles

Shotgun-metagenomics may give valuable clinical information beyond the detection of potential pathogen(s). Identification of antimicrobial resistance (AMR), virulence genes and typing directly from clinical samples has been limited due to challenges arising from incomplete genome coverage. We assessed the performance of shotgun-metagenomics on positive blood culture bottles (n = 19) with periprosthetic tissue for typing and prediction of AMR and virulence profiles in Staphylococcus aureus. We used different approaches to determine if sequence data from reads provides more information than from assembled contigs. Only 0.18% of total reads was derived from human DNA. Shotgun-metagenomics results and conventional method results were consistent in detecting S. aureus in all samples. AMR and known periprosthetic joint infection virulence genes were predicted from S. aureus. Mean coverage depth, when predicting AMR genes was 209 ×. Resistance phenotypes could be explained by genes predicted in the sample in most of the cases. The choice of bioinformatic data analysis approach clearly influenced the results, i.e. read-based analysis was more accurate for pathogen identification, while contigs seemed better for AMR profiling. Our study demonstrates high genome coverage and potential for typing and prediction of AMR and virulence profiles in S. aureus from shotgun-metagenomics data.

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.

Shotgun-Metagenomics on Positive Blood Culture Bottles Inoculated With Prosthetic Joint Tissue: A Proof of Concept Study

Clinical metagenomics is actively moving from research to clinical laboratories. It has the potential to change the microbial diagnosis of infectious diseases, especially when detection and identification of pathogens can be challenging, such as in prosthetic joint infection (PJI). The application of metagenomic sequencing to periprosthetic joint tissue (PJT) specimens is often challenged by low bacterial load in addition to high level of inhibitor and contaminant host DNA, limiting pathogen recovery. Shotgun-metagenomics (SMg) performed directly on positive blood culture bottles (BCBs) inoculated with PJT may be a convenient approach to overcome these obstacles. The aim was to test if it is possible to perform SMg on PJT inoculated into BCBs for pathogen identification in PJI diagnosis. Our study was conducted as a laboratory method development. For this purpose, spiked samples (positive controls), negative control and clinical tissue samples (positive BCBs) were included to get a comprehensive overview. We developed a method for preparation of bacterial DNA directly from PJT inoculated in BCBs. Samples were processed using MolYsis5 kit for removal of human DNA and DNA extracted with BiOstic kit. High DNA quantity/quality was obtained, and no inhibition was observed during the library preparation, allowing further sequencing process. DNA sequencing reads obtained from the BCBs, presented a low proportion of human reads (<1%) improving the sensitivity of bacterial detection. We detected a 19-fold increase in the number of reads mapping to human in a sample untreated with MolYsis5. Taxonomic classification of clinical samples identified a median of 96.08% (IQR, 93.85-97.07%; range 85.7-98.6%) bacterial reads. Shotgun-metagenomics results were consistent with the results from a conventional BCB culture method, validating our approach. Overall, we demonstrated a proof of concept that it is possible to perform SMg directly on BCBs inoculated with PJT, with potential of pathogen identification in PJI diagnosis. We consider this a first step in research efforts needed to face the challenges presented in PJI diagnoses.