Commonly Encountered Skin Biome-Derived Pathogens after Orthopedic Surgery

Spectrum of Pathogens in Surgical Site Infections after Sarcoma Resection in the Peri-Pelvic and Pelvic Region. Distinct Location, Distinct Infection?

Background: Soft tissue sarcomas (STS) often occur in the peri-pelvic region (proximal thigh, groin, gluteal region). A common complication following resection of STS is surgical site infection (SSI). The peri-pelvic site appears to be particularly problematic. Surgical site infections are associated with a high proportion of gram-negative and anaerobic micro-organisms. To date, there are no published recommendations for peri-operative antibiotic prophylaxis in pelvic STS resection. Therefore, the aim of this study was to determine the rate of SSI and the spectrum of micro-organisms detected in this region. Methods: In this monocentric study, 366 patients were retrospectively evaluated. All of these patients had undergone surgery for STS in the peri-pelvic and pelvic regions. Surgical site infections were recorded, and the microbial spectrum was analyzed. Results: There were 85 (23.2%) patients with SSI, and 188 revisions were required in these patients (2.21 per case). Swabs were sterile in 20% of clinically infected cases. In total, 36.5% of infections were polymicrobial. The most common bacteria were coagulase-negative staphylococci in 31.5%, followed by Enterococcus species in 13.3% and Escherichia coli in 7.7%. In total, 30.8% of the bacteria were gram-negative and 25.9% were anaerobic. Conclusions: Our results demonstrate the uniqueness of the bacterial spectrum of SSI after STS resection in the peri-pelvic region. In the authors' opinion, recommendations regarding the peri-operative antibiotic prophylaxis need to be adapted for the typical microbial spectrum at this site.

Multiplexed bacterial pathogen detection and clinical characteristics of orthopedic infection in hospitalized patients

Introduction

Accurate identification of the etiology of orthopedic infection is very important for correct and timely clinical management, but it has been poorly studied. In the current study we explored the association of multiple bacterial pathogens with orthopedic infection.

Methods

Hospitalized orthopedic patients were enrolled in a rural hospital in Qingdao, China. Wound or exudate swab samples were collected and tested for twelve bacterial pathogens with both culture and multiplex real time PCR.

Results and discussion

A total of 349 hospitalized orthopedic patients were enrolled including 193 cases presenting infection manifestations upon admission and 156 with no sign of infection. Orthopedic infection patients were mainly male (72.5%) with more lengthy hospital stay (median 15 days). At least one pathogen was detected in 42.5% (82/193) of patients with infection while 7.1% (11/156) in the patients without infection (P < 0.001). S. aureus was the most prevalent causative pathogen (15.5%). Quantity dependent pathogen association with infection was observed, particularly for P. aeruginosa and K. pneumoniae, possibly indicating subclinical infection. Most of the patients with detected pathogens had a previous history of orthopedic surgery (odds ratio 2.8, P = 0.038). Pathogen specific clinical manifestations were characterized. Multiplex qPCR, because of its high sensitivity, superior specificity, and powerful quantification could be utilized in combination with culture to guide antimicrobial therapy and track the progression of orthopedic infection during treatment.

Association of coagulase-negative staphylococci with orthopedic infections detected by in-house multiplex real-time PCR

Introduction

Clinical significance of coagulase-negative staphylococci (CoNS) has been gradually acknowledged in both healthcare and clinical research, but approaches for their precise discrimination at the species level remain scarce. The current study aimed to evaluate the association of CoNS with orthopedic infections, where accurate and prompt identification of etiology is crucial for appropriate diagnosis and treatment decision-making.

Methods

A 16S rRNA-based quantitative PCR (qPCR) assay was developed for the detection of Staphylococcus genus and two panels of 3-plex qPCR assays for further differentiation of six CoNS species with remarkable clinical significance, including S. epidermidis, S. haemolyticus, S. simulans, S. hominis, S. capitis, and S. caprae. All the assays exhibited excellent analytical performance. ΔCq (quantification cycle) between 16S rRNA and CoNS species-specific targets was established to determine the primary CoNS. These methods were applied to detect CoNS in wound samples from orthopedic patients with and without infection.

Results and discussion

Overall, CoNS were detected in 17.8% (21/118) of patients with clinically suspected infection and in 9.8% (12/123) of patients without any infection symptom (p < 0.05). Moreover, the association with infection was found to be bacterial quantity dependent. S. epidermidis was identified as the predominant species, followed by S. simulans, S. haemolyticus, and S. hominis. Male sex, open injury, trauma, and lower extremity were determined as risk factors for CoNS infections. CoNS-positive patients had significantly longer hospitalization duration (20 days (15, 33) versus 13 days (7, 22) for Staphylococcus-negative patients, p = 0.003), which could be a considerable burden for healthcare and individual patients. Considering the complex characteristics and devastating consequences of orthopedic infections, further expanding the detection scope for CoNS may be pursued to better understand the etiology of orthopedic infections and to improve therapeutic strategies.

Antibacterial activities of titanium dioxide (TiO2) nanotube with planar titanium silver (TiAg) to prevent orthopedic implant infection

BACKGROUND

Orthopedic implant infection has become a common catastrophic complication after various orthopedic implants, which can lead to prolonged use of antibiotics and even surgical failure. The quality of care (QoC) of orthopedic implant infection is very important.

METHODS

Titanium dioxide (TiO2) nanotube array with planar TiAg was prepared, and their antibacterial rates were tested. 400 patients hospitalized in the Department of Orthopedics of Wuhan Fourth Hospital from May 2019 to May 2020 were selected as controls (before QoC evaluation system of orthopedics), and 400 patients hospitalized from June 2020 to June 2021 were selected as observation group (after QoC evaluation system of orthopedics).

RESULTS

Regardless of Staphylococcus aureus or Escherichia coli, the antibacterial rate of TiO2 nanotube array with planar TiAg was clearly higher than that of pure iron film on the 10th and 20th days (P < 0.05). The accuracy of hospitalization assessment, disease assessment, adverse event intervention, nursing record filing and nursing satisfaction in observation group were higher as against controls (P < 0.05).

CONCLUSION

The TiO2 nanotube array with planar TiAg has good antibacterial property, which can effectively prevent orthopedic implant infection. The construction of QoC evaluation system for orthopedic specialists can effectively improve the QoC of orthopedic specialists.

Principles of mechanical and chemical debridement with implant retention

BACKGROUND

Periprosthetic joint infection (PJI) is one of the most common causes of early revision for total hip and knee arthroplasty. Mechanical and chemical debridement typically referred to as debridement, antibiotics, and implant retention (DAIR) can be a successful technique to eradicate PJI in acute postoperative or acute hematogenous infections. This review will focus specifically on the indications, techniques, and outcomes of DAIR.

DISCUSSION

The success of mechanical and chemical debridement, or a DAIR operation, is reliant on a combination of appropriate patient selection and meticulous technique. There are many technical considerations to take into consideration. One of the most important factors in the success of the DAIR procedure is the adequacy of mechanical debridement. Techniques are surgeon-specific and perhaps contribute to the large variability in the literature on the success of DAIR. Factors that have been shown to be associated with success include the exchange of modular components, performing the procedure within seven days or less of symptom onset, and possibly adjunctive rifampin or fluoroquinolone therapy, though this remains controversial. Factors that have been associated with failure include rheumatoid arthritis, age greater than 80 years, male sex, chronic renal failure, liver cirrhosis, and chronic obstructive pulmonary disease.

CONCLUSIONS

DAIR is an effective treatment option for the management of an acute postoperative or hematogenous PJI in the appropriately selected patient with well-fixed implants.

In vitro visualization and quantitative characterization of Pseudomonas aeruginosa biofilm growth dynamics on polyether ether ketone

Prevention and treatment of orthopedic device-related infection (ODRI) is complicated by the formation of bacterial biofilms. Biofilm formation involves dynamic production of macromolecules that contribute to the structure of the biofilm over time. Limitations to clinically relevant and translational biofilm visualization and measurement hamper advances in this area of research. In this paper, we present a multimodal methodology for improved characterization of Pseudomonas aeruginosa grown on polyether ether ketone (PEEK) as a model for ODRI. PEEK discs were inoculated with P. aeruginosa, incubated for 4-48 h time intervals, and fixed with 10% neutral-buffered formalin. Samples were stained with fluorescent dyes to measure biofilm components, imaged with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), and quantified. We were able to visualize and quantify P. aeruginosa biofilm growth on PEEK implants over 48 h. Based on imaging data, we propose a generalized growth cycle that can inform orthopedic diagnostic and treatment for this pathogen on PEEK. These results demonstrate the potential of using a combined CLSM and SEM approach for determining biofilm structure, composition, post-adherence development on orthopedic materials. This model may be used for quantitative biofilm analysis for other pathogens and other materials of orthopedic relevance for translational study of ODRI.

Silver carboxylate-doped titanium dioxide-polydimethylsiloxane coating decreases Cutibacterium acnes adherence and biofilm formation on polyether ether ketone

BACKGROUND CONTEXT

Cutibacterium acnes (C. acnes) is a gram-positive facultative anaerobe found in the deep sebaceous follicles of the skin on the shoulder and back. C. acnes has been increasingly recognized as a pathogen in spinal surgical site infection (SSI) especially in the presence of instrumentation.

PURPOSE

This study assesses whether a silver carboxylate-doped titanium dioxide-polydimethylsiloxane (TiO₂-PDMS) coating can decrease C. acnes adherence and biofilm formation on PEEK and four other commonly used spinal implant materials, stainless steel, cobalt chromium, titanium, and titanium alloy.

STUDY DESIGN

We compared the adherence of C. acnes over 24 hours between uncoated, 95:5 TiO₂ to PDMS ratio with 10× silver carboxylate coating and a 100% silver carboxylate coating on each implant material, which were uniformly saw cut and sterilized. Implants were then subjected to scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM).

METHODS

Samples were coated using 95:5 TiO₂-PDMS 10× silver carboxylate, 100% silver carboxylate, or left uncoated. C. acnes was applied onto the samples and allowed to adhere for periods of 4, 8, 12, 16, or 20 hours. Nonadherent bacteria were then washed from the samples. These samples were then allowed to continue incubating for a total of 24 hours. SEM and confocal laser scanning microscope were used to visualize all samples for the presence of biofilm and quantification of C. acnes adherence at each time point.

RESULTS

The 95:5 TiO₂-PDMS 10× silver carboxylate coating was able to significantly decrease C. acnes adherence on PEEK after 8, 12, 16, and 20 hours of adherence. No statistical difference was found between the 95:5 TiO₂-PDMS 10× silver carboxylate coating and the 100% silver carboxylate positive control. We previously observed extensive C. acnes biofilm formation on uncoated PEEK, but none on PEEK coated with either the 95:5 TiO₂-PDMS 10× silver carboxylate or 100% Ag coating . Furthermore, no biofilm formation was observed on stainless steel, cobalt chromium, titanium, and titanium alloy coated with 95:5 TiO₂-PDMS 10× silver carboxylate or 100% Ag coating.

CONCLUSION

A 95:5 TiO₂-PDMS 10× silver carboxylate coating decreases C. acnes adhesion and prevents biofilm formation on PEEK and other common orthopedic implant materials.

CLINICAL SIGNIFICANCE

A 95:5 TiO₂-PDMS 10× silver carboxylate coating may help decrease spinal SSI due to C. acnes, especially in procedures with instrumentation.

Synergistic Effects of Silver Carboxylate and Chlorhexidine Gluconate for Wound Care and Prevention of Surgical Site Inflections by Cutibacterium acnes and Methicillin-Resistant Staphylococcus aureus

Background: This study presents the effectiveness of a combined silver carboxylate (AgCar) and chlorohexidine gluconate (AgCar:CHG) chemistry assessed against two commonly encountered nosocomial pathogens, Methicillin-resistant Staphylococcus aureus (MRSA) and Cutibacterium acnes, within the context of surgical antisepsis and wound care. Methods: Through an Institutional Review Board- and Institutional Animal Care and Use Committee (IACUC)-approved protocol, AgCar:CHG was applied to live Yucatan porcine skin and visualized by fast red and green staining to assess level of skin penetration. Dose response curves for Cutibacterium acnes and MRSA were generated to determine the optimal therapeutic ratio of AgCar to CHG. Coatings were applied to two different clinically available sutures and antimicrobial efficacy was evaluated at 24-hour intervals using Kirby-Bauer (KB) assays. Graphite furnace atomic absorption spectroscopy was used to measure AgCar elution from sutures over time. Results: Synergistic application of AgCar:CHG demonstrated deep pilosebaceous gland penetration on Yucatan pig skin. The therapeutic concentration range of AgCar was determined to be between 120 × -150 × and 30 × -60 × dopage for MRSA and Cutibacterium acnes, respectively. A 1:1 therapeutic ratio of AgCar to CHG was found to have 100% bactericidal activity against both pathogens. Sutures coated with AgCar:CHG showed sustained antimicrobial activity against MRSA and Cutibacterium acnes, and were significantly more efficacious than antimicrobial sutures over the three- to four-day period (p < 0.01). Conclusions: This AgCar:CHG chemistry demonstrates deep skin penetration, extended elution, and broad-spectrum antimicrobial activity compared with commercially available options. This chemistry shows promise as an additional tool for the prophylaxis of surgical site infections.

Comparative meta-omics for identifying pathogens associated with prosthetic joint infection

Prosthetic joint infections (PJI) are economically and personally costly, and their incidence has been increasing in the United States. Herein, we compared 16S rRNA amplicon sequencing (16S), shotgun metagenomics (MG) and metatranscriptomics (MT) in identifying pathogens causing PJI. Samples were collected from 30 patients, including 10 patients undergoing revision arthroplasty for infection, 10 patients receiving revision for aseptic failure, and 10 patients undergoing primary total joint arthroplasty. Synovial fluid and peripheral blood samples from the patients were obtained at time of surgery. Analysis revealed distinct microbial communities between primary, aseptic, and infected samples using MG, MT, (PERMANOVA p = 0.001), and 16S sequencing (PERMANOVA p < 0.01). MG and MT had higher concordance with culture (83%) compared to 0% concordance of 16S results. Supervised learning methods revealed MT datasets most clearly differentiated infected, primary, and aseptic sample groups. MT data also revealed more antibiotic resistance genes, with improved concordance results compared to MG. These data suggest that a differential and underlying microbial ecology exists within uninfected and infected joints. This study represents the first application of RNA-based sequencing (MT). Further work on larger cohorts will provide opportunities to employ deep learning approaches to improve accuracy, predictive power, and clinical utility.

Inflammatory prognostic scoring systems are risk factors for surgical site infection following wide local excision of soft tissue sarcoma

Introduction

Limb-sparing surgery with negative margins is possible in most soft tissue sarcoma (STS) resections and focuses on maximising function and minimising morbidity. Various risk factors for surgical site infections (SSIs) have been reported in the literature specific to sarcoma surgery. The aim of this study is to determine whether systemic inflammatory response prognostic scoring systems can predict post-operative SSI in patients undergoing potentially curative resection of STS.

Methods

Patients who had a planned curative resection of a primary STS at a single centre between January 2010 and December 2019 with a minimum follow-up of 6 months were included. Data were extracted on patient and tumour characteristics, and pre-operative blood results were used to calculate inflammatory prognostic scores based on published thresholds and correlated with risk of developing SSI or debridement procedures.

Results

A total of 187 cases were included. There were 60 SSIs. On univariate analysis, there was a statistically significant increased risk of SSI in patients who are diabetic, increasing specimen diameter, American Society of Anaesthesiology (ASA) grade 3, use of endoprosthetic replacement, blood loss greater than 1 L, and junctional tumour location. Modified Glasgow prognostic score, C-reactive protein/albumin ratio and neutrophil–platelet score (NPS) were statistically associated with the risk of SSI. On multivariate analysis, ASA grade 3, junctional tumour location and NPS were independently associated with the risk of developing a SSI.

Conclusion

This study supports the routine use of simple inflammation-based prognostic scores in identifying patients at increased risk of developing infectious complications in patients undergoing potentially curative resection of STS.

Review of Pre-Operative Skin Preparation Options Based on Surgical Site in Orthopedic Surgery

Background: Surgical site infections (SSIs) are a primary contributor to surgical morbidity and mortality, causing a substantial financial burden on the healthcare system. Specifically, Cutibacterium acnes contributes greatly to infections in the shoulder and spine regions. Prevention of infection is crucial to improve patient outcomes and reduce costs. This article reviews current surgical skin preparation solutions, the unique distribution of organisms at common orthopedic surgical sites, and recommends solutions based on surgical location. Methods: A search of electronic databases (PubMed, MEDLINE, and Embase) was conducted for relevant literature until December 2020. Sources were compiled based on title and abstract, then full texts were read for possible inclusion. This review summarizes the most recent publications in the field of SSIs and preparation solutions. Results: The mechanism and efficacy of alcohol-, iodine-, and chlorhexidine-based preparations were reviewed, along with experimental preparations. This article identifies common colonization patterns for the shoulder, elbow, hip, knee, spine, foot, and ankle, and discusses recommendations for preparations based on current evidence. Recommendations: For shoulder and elbow operations, we recommend ChloraPrep™ (CareFusion, BD, El Paso, TX), DuraPrep™ (3M Health Care, St. Paul, MN), or Betadine^® applied with 4 × 4 gauze sponge, three-day pre-operative benzyl peroxide, and application of 3% hydrogen peroxide before skin preparation. For the hip and knee, we recommend application of 2% chlorhexidine gluconate (CHG) cloth the night before and morning of surgery and either DuraPrep or iodine-alcohol skin prep prior to surgery. For spine surgeries, we recommended ChloraPrep. For foot and ankle, our recommendations are: ChloraPrep or DuraPrep, submersion of foot in 70% ethanol/10% isopropyl alcohol for five minutes prior to procedure, application with a bristled brush, and a second vigorous scrub with 4 × 4 soaked gauze. Conclusions: The current surgical skin preparations have both benefits and drawbacks. We recommend that orthopedic surgeons choose a skin preparation based on surgical site and prevalence of unique skin flora there.

Current Clinical Methods for Detection of Peri-Prosthetic Joint Infection

Background: Currently, one of the most pressing problems in the field of orthopedic surgery is peri-prosthetic joint infection [PJI]. While there are numerous ways to detect PJI, current clinical detection methods differ across institutions and have varying criteria and protocols. Some of these methods include the Modified Musculoskeletal Infection Society system, culturing, polymerase chain reaction, the determination of the presence of certain biomarkers, testing for the presence of alpha defensin peptides, and leukocyte level testing. Methods: This review summarizes the most recent publications in the field of PJI detection to highlight current strengths as well as provide future directions to find the system for the quickest, cost-effective, and most accurate way to diagnose these types of infections. Results: The results of this literature review suggest that, while each method of diagnosis has its advantages, each has various drawbacks as well. Current methods can be expensive, take days to weeks to complete, be prone to contamination, and can produce ambiguous results. Conclusions: The findings in this review emphasize the need for a more comprehensive and accurate system for diagnosing PJI. In addition, the specific comparison of advantages and drawbacks can be useful for researchers and clinicians with goals of creating new diagnostic tests for PJIs, as well as in clinical scenarios to determine the correct treatment for patients.