Clinical applications of metagenomic next-generation sequencing in the identification of pathogens in periprosthetic joint infections: a retrospective study.

BACKGROUND: This study aimed to evaluate the application of metagenomic next-generation sequencing (mNGS) technology to identify pathogens in periprosthetic joint infection (PJI). METHODS: A retrospective analysis was conducted on 65 patients suspected of having PJI between April 2020 and July 2023. The patients were categorized into PJI (46 patients) and non-PJI (19 patients) groups based on the 2018 International Consensus Meeting criteria. Clinical data were collected, and both conventional bacterial culture and mNGS were performed. The diagnostic performance of the two methods was compared and analyzed. RESULTS: mNGS exhibited a sensitivity of 89.13%, a specificity of 94.74%, a positive predictive value of 97.62%, a negative predictive value of 78.26%, and an overall diagnostic accuracy of 90.77%. Compared to microbial culture, mNGS demonstrated superior diagnostic sensitivity while maintaining similar specificity. A total of 48 pathogens were successfully identified using mNGS, with Coagulase-negative staphylococci, Streptococci, Staphylococcus aureus, and Cutibacterium acnes being the most common infectious agents. Notably, mNGS was used to identify 17 potential pathogens in 14 culture-negative PJI samples, highlighting its ability to detect rare infectious agents, including Cutibacterium acnes (n = 5), Granulicatella adiacens (n = 1), Mycobacterium tuberculosis complex (n = 1), and Coxiella burnetii (n = 1), among others, which are not detectable by routine culture methods. However, mNGS failed to detect the pathogen in 4 culture-positive PJI patients, indicating its limitations. Among the 46 PJI patients, 27 had positive culture and mNGS results. The results of mNGS were concordant with those of culture at the genus level in 6 patients with PJI and at the species level in 18 patients. Furthermore, the present study revealed a significantly greater proportion of Staphylococcus aureus in the sinus tract group (45.45%) than in the non-sinus tract group (14.29%), indicating the association of this pathogen with sinus formation in PJI (P = 0.03). Additionally, there was no significant difference in the occurrence of polymicrobial infections between the sinus tract group (27.27%) and the non-sinus tract group (33.33%) (P = 0.37). CONCLUSIONS: Metagenomic next-generation sequencing can serve as a valuable screening tool in addition to traditional culture methods to improve diagnostic accuracy through optimized culture strategies.

Triggered Release of Ampicillin from Metallic Implant Coatings for Combating Periprosthetic Infections.

Periprosthetic infections caused by Staphylococcus aureus (S. aureus) pose unique challenges in orthopedic surgeries, in part due to the bacterium's capacity to invade surrounding bone tissues besides forming recalcitrant biofilms on implant surfaces. We previously developed prophylactic implant coatings for the on-demand release of vancomycin, triggered by the cleavage of an oligonucleotide (Oligo) linker by micrococcal nuclease (MN) secreted by the Gram-positive bacterium, to eradicate S. aureus surrounding the implant in vitro and in vivo. Building upon this coating platform, here we explore the feasibility of extending the on-demand release to ampicillin, a broad-spectrum aminopenicillin ß-lactam antibiotic that is more effective than vancomycin in killing Gram-negative bacteria that may accompany S. aureus infections. The amino group of ampicillin was successfully conjugated to the carboxyl end of an MN-sensitive Oligo covalently integrated in a polymethacrylate hydrogel coating applied to titanium alloy pins. The resultant Oligo-Ampicillin hydrogel coating released the ß-lactam in the presence of S. aureus and successfully cleared nearby S. aureus in vitro. When the Oligo-Ampicillin-coated pin was delivered to a rat femoral canal inoculated with 1000 cfu S. aureus, it prevented periprosthetic infection with timely on-demand drug release. The clearance of the bacteria from the pin surface as well as surrounding tissue persisted over 3 months, with no local or systemic toxicity observed with the coating. The negatively charged Oligo fragment attached to ampicillin upon cleavage from the coating did diminish the antibiotic's potency against S. aureus and Escherichia coli (E. coli) to varying degrees, likely due to electrostatic repulsion by the anionic surfaces of the bacteria. Although the on-demand release of the ß-lactam led to adequate killing of S. aureus but not E. coli in the presence of a mixture of the bacteria, strong inhibition of the colonization of the remaining E. coli on hydrogel coating was observed. These findings will inspire considerations of alternative broad-spectrum antibiotics, optimized drug conjugation, and Oligo linker engineering for more effective protection against polymicrobial periprosthetic infections.

Development of a multiplex Loop-Mediated Isothermal Amplification (LAMP) for the diagnosis of bacterial periprosthetic joint infection.

BACKGROUND: Periprosthetic joint infection (PJI) is one of the most serious and debilitating complications that can occur after total joint arthroplasty. Therefore, early diagnosis and appropriate treatment are important for a good prognosis. Recently, molecular diagnostic methods have been widely used to detect the causative microorganisms of PJI sensitively and rapidly. The Multiplex Loop-Mediated Isothermal Amplification (LAMP) method eliminates the complex temperature cycling and delays caused by temperature transitions seen in polymerase chain reaction (PCR) methods, making it faster and easier to perform compared to PCR-based assays. Therefore, this study developed a multiplex LAMP assay for diagnosing bacterial PJI using LAMP technology and evaluated its analytical and clinical performance. METHODS: We developed a multiplex LAMP assay for the detection of five bacteria: Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus agalactiae, Pseudomonas aeruginosa, and Escherichia coli, frequently observed to be the causative agents of PJI. The method of analytical sensitivity and cross-reactivity were determined by spiking standard strains into the joint synovial fluid. The analytical sensitivity of the multiplex LAMP assay was compared with that of a quantitative real-time PCR (qPCR) assay. Clinical performance was evaluated using 20 joint synovial fluid samples collected from patients suspected of having bacterial PJI. RESULTS: The analytical sensitivity of the gram-positive bacterial multiplex LAMP assay and qPCR were 105/104 CFU/mL, 103/103 CFU/mL, and 105/104 CFU/mL against S. agalactiae, S. epidermidis, and S. aureus, respectively. For P. aeruginosa and E. coli, the analytical sensitivity of the multiplex LAMP and qPCR assays were 105/104 and 106/104 CFU/mL, respectively. The multiplex LAMP assay detects target bacteria without cross-reacting with other bacteria, and exhibited 100% sensitivity and specificity in clinical performance evaluation. CONCLUSIONS: This multiplex LAMP assay can rapidly detect five high-prevalence bacterial species causing bacterial PJI, with excellent sensitivity and specificity, in less than 1 h, and it may be useful for the early diagnosis of PJI.

Use of thioglycolate broth as a pre-analytic transport medium in the diagnosis of prosthetic joint infection.

OBJECTIVES: This study aimed to investigate whether adding tissue samples directly into thioglycolate (TG) broth yielded a greater number of anaerobic organisms than freshly sampled tissue in suspected hip and knee prosthetic joint infections (PJIs). PATIENTS AND METHODS: Between January 2017 and December 2020, a total of 90 patients (46 males, 44 females; median age: 71.7 years; range, 50.8 and 87.8 years) who underwent revision hip or knee arthroplasty were included. Intraoperative samples were taken, with five placed in TG broth and five in standard containers (PC) with subsequent aerobic and anaerobic culturing conducted. Demographic and baseline data of the patients were recorded. The primary outcome was positive bacterial growth from a PJI specimen inoculated directly into TG broth at the time of collection or standard PJI specimen processing. Secondary outcomes investigated were the presence of Cutibacterium acnes (C. acnes) and the curative success of revision procedure. RESULTS: A total of 900 samples (450 PC and 450 TG) were taken from 90 revision arthroplasty patients (47 knees and 43 hips). There was no statistically significant difference in the number of positive bacterial growth samples between TG broth and standard processing (p=0.742). This was consistent with subgroup analysis analyzing C. acnes (p=0.666). CONCLUSION: In hip and knee arthroplasty, there is no benefit in substituting or adding TG broth as a culture medium to better identify both general bacterial species and C. acnes infections specifically. However, the use of TG may be useful in confirming a true positive result for infection.

An In Vitro Study on the Application of Silver-Doped Platelet-Rich Plasma in the Prevention of Post-Implant-Associated Infections.

Implant therapy is a common treatment option in dentistry and orthopedics, but its application is often associated with an increased risk of microbial contamination of the implant surfaces that cause bone tissue impairment. This study aims to develop two silver-enriched platelet-rich plasma (PRP) multifunctional scaffolds active at the same time in preventing implant-associated infections and stimulating bone regeneration. Commercial silver lactate (L) and newly synthesized silver deoxycholate:ß-Cyclodextrin (B), were studied in vitro. Initially, the antimicrobial activity of the two silver soluble forms and the PRP enriched with the two silver forms has been studied on microbial planktonic cells. At the same time, the biocompatibility of silver-enriched PRPs has been assessed by an MTT test on human primary osteoblasts (hOBs). Afterwards, an investigation was conducted to evaluate the activity of selected concentrations and forms of silver-enriched PRPs in inhibiting microbial biofilm formation and stimulating hOB differentiation. PRP-L (0.3 µg/mm2) and PRP-B (0.2 µg/mm2) counteract Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans planktonic cell growth and biofilm formation, preserving hOB viability without interfering with their differentiation capability. Overall, the results obtained suggest that L- and B-enriched PRPs represent a promising preventive strategy against biofilm-related implant infections and demonstrate a new silver formulation that, together with increasing fibrin binding protecting silver in truncated cone-shaped cyclic oligosaccharides, achieved comparable inhibitory results on prokaryotic cells at a lower concentration.

Biofilm on total joint replacement materials can be reduced through electromagnetic induction heating using a portable device.

BACKGROUND: Periprosthetic joint infection is a serious complication following joint replacement. The development of bacterial biofilms bestows antibiotic resistance and restricts treatment via implant retention surgery. Electromagnetic induction heating is a novel technique for antibacterial treatment of metallic surfaces that has demonstrated in-vitro efficacy. Previous studies have always employed stationary, non-portable devices. This study aims to assess the in-vitro efficacy of induction-heating disinfection of metallic surfaces using a new Portable Disinfection System based on Induction Heating. METHODS: Mature biofilms of three bacterial species: S. epidermidis ATCC 35,984, S. aureus ATCC 25,923, E. coli ATCC 25,922, were grown on 18 × 2 mm cylindrical coupons of Titanium-Aluminium-Vanadium (Ti6Al4V) or Cobalt-chromium-molybdenum (CoCrMo) alloys. Study intervention was induction-heating of the coupon surface up to 70ºC for 210s, performed using the Portable Disinfection System (PDSIH). Temperature was monitored using thermographic imaging. For each bacterial strain and each metallic alloy, experiments and controls were conducted in triplicate. Bacterial load was quantified through scraping and drop plate techniques. Data were evaluated using non-parametric Mann-Whitney U test for 2 group comparison. Statistical significance was fixed at p ≤ 0.05. RESULTS: All bacterial strains showed a statistically significant reduction of CFU per surface area in both materials. Bacterial load reduction amounted to 0.507 and 0.602 Log10 CFU/mL for S. aureus on Ti6Al4V and CoCrMo respectively, 5.937 and 3.500 Log10 CFU/mL for E. coli, and 1.222 and 0.372 Log10 CFU/mL for S. epidermidis. CONCLUSIONS: Electromagnetic induction heating using PDSIH is efficacious to reduce mature biofilms of S aureus, E coli and S epidermidis growing on metallic surfaces of Ti6Al4V and CoCrMo alloys.

The Clinical Challenge of Prosthetic Valve Endocarditis: JACC Focus Seminar 3/4.

During the past 6 decades, there have been numerous changes in prosthetic valve endocarditis (PVE), currently affecting an older population and increasing in incidence in patients with transcatheter-implanted valves. Significant microbiologic (molecular biology) and imaging diagnostic (fluorine-18 fluorodeoxyglucose-positron emission tomography/computed tomography) advances have been incorporated into the 2023 Duke-International Society for Cardiovascular Infectious Diseases infective endocarditis diagnostic criteria, thus increasing the diagnostic sensitivity for PVE without sacrificing specificity in validation studies. PVE is a life-threatening disease requiring management by multidisciplinary endocarditis teams in cardiac centers to improve outcomes. Novel surgical options are now available, and an increasing set of patients may avoid surgical intervention despite indication. Selected patients may complete parenteral or oral antimicrobial treatment at home. Finally, patients with prosthetic valves implanted surgically or by the transcatheter approach are candidates for antibiotic prophylaxis before invasive dental procedures.

The Effect of Slime Factor in the Treatment of Spinal Implant Infections.

AIM: To investigate the effect of the biofilm-forming ability of the bacteria on treatment in rats by using biofilm-forming and nonbiofilm- forming strains of Staphylococcus aureus (S. aureus). MATERIAL AND METHODS: Forty rats were divided into four equal groups as Group 1A, 1B, 2A, and 2B. All rats underwent single distance lumbar laminectomy, and titanium implants were introduced. Group 1 rats were inoculated with Slime factor (-) S. aureus, while Group 2 rats were inoculated with biofilm Slime factor (+) S. aureus. None of the rats were given antibiotics. One week later, the surgical field was reopened and microbiological samples were taken. The implants of rats in Groups 1A and 2A were left in place, while the implants of rats in Groups 1B and 2B were removed. RESULTS: There was no statistically significant difference between the groups inoculated with slime factor (+) S. aureus; although, Groups 1A and 2A showed statistically significant difference. Statistical analysis with respect to bacterial count also showed a statistically significant difference between Groups 1A and 2A. There was a statistically significant difference between Group 1B and 2B. CONCLUSION: The results obtained in the present study reveal that in case of implant-dependent infection, the first sample taken can be checked for slime factor, and if there is infection with slime factor-negative bacterium, treatment without removing the implant may be recommended. S. aureus was used in the study because it is the most common cause of implant-related infection at surgical sites. Further studies using different bacterial species are needed to reach a definitive conclusion.

A comparison of the prevalence of respiratory pathogens and opportunistic respiratory pathogenic profile of 'clean' and 'unclean' removable dental prostheses.

OBJECTIVES: To determine and compare the opportunistic respiratory pathogenic index (ORPI) and prevalence of respiratory pathogens between clean and unclean removable prostheses. METHODS: A cross-sectional study was conducted among 97 removable prosthesis wearers at a teaching dental hospital. Participants' prosthesis hygiene was grouped into clean and unclean. After prosthesis plaque samples were sequenced using the Type IIB Restriction-site Associated DNA Sequencing for Microbiome method, the prevalence was assessed for the presence of respiratory pathogens on each sample. The ORPIs for clean and unclean prostheses were quantified based on the sum of the relative abundance of respiratory pathogenic bacteria in a microbiome using a reference database that contains opportunistic respiratory pathogens and disease-associated information. RESULTS: A total of 30 opportunistic respiratory pathogens were identified on the removable prostheses. Eighty-one (83.5 %) removable prostheses harboured respiratory pathogenic bacteria. Stenotrophomonas maltophilia (34.0 %), Pseudomonas aeruginosa (27.8 %), and Streptococcus agalactiae (27.8 %) were the top three prevalent respiratory pathogens detected in plaque samples. There was a significantly higher prevalence of respiratory pathogens residing on unclean than clean prostheses (P = 0.046). However, the ORPIs in both groups showed no statistically significant difference (P = 0.516). CONCLUSIONS: The ORPIs for both clean and unclean prostheses demonstrated a similar abundance of respiratory pathogens. However, the high prevalence of respiratory pathogens residing on unclean prostheses should not be underestimated. Therefore, maintaining good prosthesis hygiene is still important for overall oral and systemic health, even though the direct link between prosthesis cleanliness and reduced abundance of respiratory pathogens has not been established. CLINICAL SIGNIFICANCE: The association between the prevalence of respiratory pathogens and unclean removable prostheses has been demonstrated and might increase the theoretical risk of respiratory disease development.

Outcomes in orthopedic device infections due to Streptococcus agalactiae: a retrospective cohort study.

BACKGROUND: Group B streptococci (Streptococcus agalactiae) (GBS) is a rare cause of prosthetic joint infection (PJI) occurring in patients with comorbidities and seems to be associated with a poor outcome. Depiction of GBS PJI is scarce in the literature. METHODS: A retrospective survey in 2 referral centers for bone joint infections was done Patients with a history of PJI associated with GBS between 2014 and 2019 were included. A descriptive analysis of treatment failure was done. Risk factors of treatment failure were assessed. RESULTS: We included 61 patients. Among them, 41 had monomicrobial (67%) infections. The median duration of follow-up was 2 years (interquartile range 2.35) Hypertension, obesity, and diabetes mellitus were the most reported comorbidities (49%, 50%, and 36% respectively). Death was observed in 6 individuals (10%) during the initial management. The rate of success was 63% (26/41). Removal of the material was not associated with remission (p = 0.5). We did not find a specific antibiotic regimen associated with a better outcome. CONCLUSION: The results show that S. agalactiae PJIs are associated with high rates of comorbidities and a high treatment failure rate with no optimal treatment so far.

Positive Culture of Atypical Mycobacterium Avium Following Revision Total Knee Arthroplasty.

CASE: We report a rare case of mycobacterial periprosthetic joint infection (PJI) after primary total knee arthroplasty 14 years earlier. Progressive knee pain over three years with a negative PJI infectious workup led to revision total knee arthroplasty. A surprising result was isolation of Mycobacterium avium from tissue cultures taken at time of revision surgery. After six months of antibiotic treatment, the patient is alive with well- functioning pain-free TKA at over one-year follow-up. CONCLUSION: Periprosthetic joint infection can present acutely or chronically years following total knee arthroplasty. Depending on the infecting organism, patients can present with sepsis, or a more indolent slower course that mimics aseptic loosening. In the absence of positive pre-operative labs and cultures, and based on the Musculoskeletal Infection Society (MSIS) criteria, aseptic loosening is a diagnosis of exclusion. An atypical infectious organism should be considered a possible cause and may require specialized cultures of operative specimens.

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.

Biofilm Microenvironment Activated Antibiotic Adjuvant for Implant-Associated Infections by Systematic Iron Metabolism Interference.

Hematoma, a risk factor of implant-associated infections (IAIs), creates a Fe-rich environment following implantation, which proliferates the growth of pathogenic bacteria. Fe metabolism is a major vulnerability for pathogens and is crucial for several fundamental physiological processes. Herein, a deferiprone (DFP)-loaded layered double hydroxide (LDH)-based nanomedicine (DFP@Ga-LDH) that targets the Fe-rich environments of IAIs is reported. In response to acidic changes at the infection site, DFP@Ga-LDH systematically interferes with bacterial Fe metabolism via the substitution of Ga3+ and Fe scavenging by DFP. DFP@Ga-LDH effectively reverses the Fe/Ga ratio in Pseudomonas aeruginosa, causing comprehensive interference in various Fe-associated targets, including transcription and substance metabolism. In addition to its favorable antibacterial properties, DFP@Ga-LDH functions as a nano-adjuvant capable of delaying the emergence of antibiotic resistance. Accordingly, DFP@Ga-LDH is loaded with a siderophore antibiotic (cefiderocol, Cefi) to achieve the antibacterial nanodrug DFP@Ga-LDH-Cefi. Antimicrobial and biosafety efficacies of DFP@Ga-LDH-Cefi are validated using ex vivo human skin and mouse IAI models. The pivotal role of the hematoma-created Fe-rich environment of IAIs is highlighted, and a nanoplatform that efficiently interferes with bacterial Fe metabolism is developed. The findings of the study provide promising guidance for future research on the exploration of nano-adjuvants as antibacterial agents.

Rapid high-throughput processing of tissue samples for microbiological diagnosis of periprosthetic joint infections using bead-beating homogenization.

Enrichment of periprosthetic tissue samples in blood culture bottles (BCBs) for microbiological diagnosis of periprosthetic joint infections (PJI) is more reliable than the use of an enrichment broth. Nevertheless, the extremely time-consuming homogenization of the samples for BCB processing has so far limited its use, especially in high-throughput settings. We aimed to establish a highly scalable homogenization process of tissue samples for long-term incubation in BCBs. A protocol for homogenization of tissue samples using bead beating was established and validated. In a second step, the use of the homogenate for enrichment in BCBs was compared to the use of thioglycolate broth (TB) in terms of diagnostic accuracy using clinical tissue samples from 150 patients with suspected PJI. Among 150 analyzed samples, 35 samples met the microbiological criteria for PJI. Using BCB, 32 of 35 (91.4%) PJI were detected compared to 30 of 35 (85.7%) by TB. The use of BCB had a lower secondary contamination rate (2/115; 1.7% vs 4/115; 3.5%) but the trend was not significant due to low numbers of samples (P = 0.39). The time to process a batch of 12 samples using the established homogenization method was 23 ± 5 min (n = 10 batches). We established and validated a homogenization workflow that achieves the highest sensitivity in the microbiological diagnostic of PJI. The enrichment of the tissue homogenate in BCBs showed equally good results as the use of enrichment broth and allows semi-automated high-throughput processing while demonstrating lower contamination rates in our study.

Outcomes After Pseudomonas Prosthetic Joint Infections.

BACKGROUND: Pseudomonas species are a less common but devastating pathogen family in prosthetic joint infections (PJIs). Despite advancements in management, Pseudomonas PJIs remain particularly difficult to treat because of limited antibiotic options and robust biofilm formation. This study aimed to evaluate Pseudomonas PJI outcomes at a single institution and review outcomes reported in the current literature. METHODS: All hip or knee PJIs at a single institution with positive Pseudomonas culture were evaluated. Forty-two patients (24 hips, 18 knees) meeting inclusion criteria were identified. The primary outcome of interest was infection clearance at 1 year after surgical treatment, defined as reassuring aspirate without ongoing antibiotic treatment. Monomicrobial and polymicrobial infections were analyzed separately. A focused literature review of infection clearance after Pseudomonas PJIs was performed. RESULTS: One-year infection clearance was 58% (n = 11/19) for monomicrobial PJIs and 35% (n = 8/23) for polymicrobial PJIs. Among monomicrobial infections, the treatment success was 63% for patients treated with DAIR and 55% for patients treated with two-stage exchange. Monotherapy with an oral or intravenous antipseudomonal agent (minimum 6 weeks) displayed the lowest 1-year clearance of 50% (n = 6/12). Resistance to antipseudomonal agents was present in 16% (n = 3/19), and two of eight patients with monomicrobial and polymicrobial PJIs developed resistance to antipseudomonal therapy in a subsequent Pseudomonas PJI. Polymicrobial infections (55%) were more common with a mortality rate of 44% (n = 10/23) at a median follow-up of 3.6 years. CONCLUSION: Pseudomonas infections often present as polymicrobial PJIs but are difficult to eradicate in either polymicrobial or monomicrobial setting. A review of the current literature on Pseudomonas PJI reveals favorable infection clearance rates (63 to 80%) after DAIR while infection clearance rates (33 to 83%) vary widely after two-stage revision.

Identification of prosthetic joint infections with 16S amplicon metagenomic sequencing - comparison with standard cultivation approach.

Prosthetic joint infections (PJIs) are commonly diagnosed via culture-based methods, which may miss hard-to-grow pathogens. This study contrasts amplicon metagenomic sequencing (16S AS) with traditional culture techniques for enhanced clinical decision-making. We analyzed sonicate fluid from 27 patients undergoing revision arthroplasty using both methods, emphasizing the distinction between contaminants and true positives. Our findings show moderate agreement between the two methods, with a Cohen's kappa of 0.490, varying across bacterial genera (Cohen's kappa -0.059 to 1). The sensitivity of 16S AS compared to culture was 81% (95% CI, 68% to 94%). Sequencing revealed greater microbial diversity, including anaerobic genera like Anaerococcus and Citrobacter. Interestingly, several culture-negative PJI samples showed diverse bacteria via 16S AS. Despite rigorous controls and algorithms to eliminate contaminants, confirming bacteria presence with 16S AS remains a challenge. This highlights the need for improved PJI diagnostic methods, while also pointing out the limitations of next-generation sequencing (NGS) as a clinical diagnostic tool.

Preventing Bacterial Contamination of Breast Implants Using Infection Mitigation Techniques: An In Vitro Study.

BACKGROUND: Bacterial contamination of implants has been linked to biofilm formation and subsequent infection, capsular contracture, and breast implant-associated anaplastic large cell lymphoma. Reducing contamination during implant insertion should therefore reduce biofilm formation disease sequelae. OBJECTIVES: The aim of this study was to compare levels of contamination between preventative techniques. METHODS: A model to simulate the passage of implants through a skin incision was designed that utilized a sterile textured polyvinyl plastic sheet contaminated with Staphylococcus epidermidis. In the first stage of the polyvinyl contamination model, implants were subject to infection-mitigation techniques and passed through the incision, then placed onto horse blood agar plates and incubated for 24 hours. In the second stage of the study the same contamination was applied to human abdominal wall specimens. A 5 cm incision was made through skin and fat, then implants were passed through and levels of contamination were measured as described. RESULTS: Smooth implants grew a mean of 95 colony-forming units (CFUs; approximately 1 CFU/cm2) and textured implants grew 86 CFUs (also approximately 1 CFU/cm2). CFU counts were analyzed by the Mann-Whitney U-test which showed no significant difference between implant types (P < .05); independent-sample t-tests showed a significant difference. The dependent-variable techniques were then compared as groups by one-way analysis of variance, which also showed a significant reduction compared with the control group (P < .01). CONCLUSIONS: This in vitro study has shown the effectiveness of antiseptic rinse and skin/implant barrier techniques for reducing bacterial contamination of breast implants at the time of insertion.

Factors affecting risk of recurrence with periprosthetic infection in shoulder arthroplasty.

BACKGROUND: The goal of treating periprosthetic infection, besides its eradication, is to avoid recurrence. The purpose of this study was to evaluate the impact of increasing Infection Severity (IS) score (based on the 2018 International Consensus Meeting on Orthopedic Infections statement), single-stage revision, and pathogenicity of the infective organism on the risk of infection recurrence. METHODS: A database of 790 revisions performed by a single surgeon from 2004-2020 was reviewed for patients with minimum 2-year follow-up and ≥1 positive culture finding and/or pathology result from the revision surgical procedure. In total, 157 cases performed in 144 patients met the inclusion criteria. These cases were then categorized by infection probability (IS score) according to the 2018 consensus statement. Of 157 cases, 46 (29%) were classified as definitely or probably infected; 25 (16%), possibly infected; and 86 (55%), unlikely to be infected. Additionally, patients were grouped by single-stage surgery and pathogenicity of the infective organism. RESULTS: A recurrence in this study was classified as the growth of the same organism in any patient requiring revision surgery. The 86 cases in the group with unlikely infection showed a recurrence rate of 2.3%. The 25 cases in the group with possible infection showed a recurrence rate of 12%. The 46 cases in the group with definite or probable infection showed a recurrence rate of 17.4%. Patients in the definite/probable infection group had a higher rate of recurrence than those in the groups with possible infection and unlikely infection (P = .009). The IS score was higher in the recurrence group than the non-recurrence group (7.5 ± 4.3 vs. 3.9 ± 3.4, P < .001). Overall, patients who underwent 1-stage revision had a 5.0% recurrence rate, but among the 34 patients with an infection classification of definite or probable who underwent 1-stage revision, the recurrence rate was 5.9%. Cases of highly virulent methicillin-resistant Staphylococcus aureus also showed a recurrence rate of 30.8% compared with 4.0% and 5.9% for Cutibacterium acnes and coagulase-negative staphylococci, respectively (P = .005). CONCLUSION: Recurrent infection after treatment of a periprosthetic infection is associated with increasing severity scores, as defined in the 2018 consensus statement, and more aggressive microorganisms. However, a single-stage surgical procedure, even in patients with higher IS scores, did not impart a significantly increased risk of recurrence.

Antibiotic-Loaded Ultrahigh Molecular Weight Polyethylenes.

The occurrence of periprosthetic joint infections (PJI) after total joint replacement constitutes a great burden for the patients and the healthcare system. Antibiotic-loaded polymethylmethacrylate (PMMA) bone cement is often used in temporary spacers during antibiotic treatment. PMMA is not a load-bearing solution and needs to be replaced by a functional implant. Elution from the ultrahigh molecular weight polyethylene (UHMWPE) bearing surface for drug delivery can combine functionality with the release of clinically relevant doses of antibiotics. In this study, the feasibility of incorporating a range of antibiotics into UHMWPE is investigated. Drug stability is assessed by thermo-gravimetric analysis and nuclear magnetic resonance spectroscopy. Drug-loaded UHMWPEs are prepared by compression molding, using eight antibiotics at different loading. The predicted intra-articular concentrations of drugs eluted from UHMWPE are above minimum inhibitory concentration for at least 3 weeks against Staphylococci, which are the major causative bacteria for PJI. The antibacterial efficacy is confirmed for samples covering 2% of a representative knee implant in vitro over 72 h, showing that a small fraction of the implant surface loaded with antibiotics may be sufficient against Staphylococci.