Prosthetic joint infection

Puncture Protocol in the Diagnostic Work-Up of a Suspected Chronic Prosthetic Joint Infection of the Hip

BACKGROUND

Diagnosing a chronic prosthetic joint infection (PJI) can be challenging. We hypothesized that obtaining preoperative tissue samples for culture in hip arthroplasty will increase the likelihood of diagnosing an infection before revision surgery. The aim of this cohort study was to determine the diagnostic accuracy of 2 tissue acquiring biopsy strategies to diagnose a PJI.

METHODS

Patients with a painful hip arthroplasty, in which a chronic PJI was suspected, were included. Tissue samples were obtained either by ultrasound guidance with a 16-Gauge needle (2012-2013) or in the operating room with a thick-bore needle (2013-2016). Revision surgery tissue biopsies were used as the gold standard. Sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio were calculated.

RESULTS

A total of 16 patients in the ultrasound cohort and 29 patients in the surgical cohort were included. Thirty-one percent (n = 14) were finally diagnosed with a PJI. The addition of thick bore needle tissue biopsies resulted in 9% more diagnosed PJIs compared with synovial fluid alone. The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio was 33%, 85%, 33%, 85%, 2.2, and 0.8, respectively, for the ultrasound-guided biopsy cohort and 82%, 100%, 100%, 90%, infinite, and 0.2, respectively, for the surgical biopsy cohort.

CONCLUSION

Obtaining multiple good quality tissue biopsies in a sterile environment will contribute to the diagnosis of a chronic PJI of the hip, with a higher diagnostic accuracy compared with ultrasound-guided thin needle biopsies and compared with synovial fluid culture alone.

Irrigation and Debridement for Early Periprosthetic Knee Infection: Is It Effective?

BACKGROUND

Irrigation and debridement (I&D) is performed for early management of periprosthetic joint infection (PJI) following total knee arthroplasty (TKA). Symptom reporting is a subjective measure and may miss direct management of PJI. Utilizing an objective time interval from index procedure to I&D may better inform treatment decisions.

METHODS

From 2009 to 2017, retrospective review was performed of 55 knee PJI cases at our institution. All patients underwent polyethylene liner exchange and I&D for PJI. Patients were stratified by time from index procedure to I&D (≤2 weeks, >2 weeks). Success was defined as eradication of infection and resolution of presenting symptoms. Failed cases required subsequent procedures due to infection.

RESULTS

Average follow-up time after index TKA was 2.5 years. Among patients with I&D within 2 weeks of index TXA, 14 patients (82%) were successfully treated while 3 (18%) had infection recurrence. These outcomes were significantly improved compared to patients with I&D after 2 weeks: 19 (50%) successes and 19 (50%) failures (P = .024). Staphylococcal species were the most frequent pathogen in patients treated before and after 2 weeks of index TKA (39% and 50%, respectively). Outcomes were pathogen-independent in PJIs treated before or after 2 weeks of index TKA (P = .206 and .594, respectively).

CONCLUSION

Our results demonstrate that patients with early PJI managed with I&D and liner exchange within 2 weeks of index TKA had higher rates of treatment success when compared to those with I&D beyond 2 weeks. These findings suggest that time from index TKA to I&D is an objective and reliable indicator of treatment success when considering I&D in acute onset knee PJI.

In vitro activity of novel anti-MRSA cephalosporins and comparator antimicrobial agents against staphylococci involved in prosthetic joint infections

OBJECTIVES

Ceftaroline and ceftobiprole are new parenteral cephalosporins with potent activity against methicillin-resistant (MR) staphylococci, which are the leading cause of prosthetic joint infections (PJIs). The aim of this study was to determine and compare the in vitro activities of both molecules against staphylococcal isolates recovered from clinically documented PJIs.

METHODS

A collection of 200 non-duplicate clinical isolates [100 Staphylococcus aureus and 100 coagulase-negative staphylococci (CoNS), including 19 and 27 MR isolates, respectively] was studied. Minimum inhibitory concentrations (MICs) of oxacillin, ceftaroline, ceftobiprole, vancomycin, teicoplanin, clindamycin, levofloxacin, linezolid and daptomycin were determined by the broth microdilution method. Bactericidal activity (at 4× MIC) of ceftaroline, ceftobiprole, vancomycin, teicoplanin, linezolid and daptomycin was assessed by time-kill assay.

RESULTS

Among the S. aureus isolates, 100% were susceptible to ceftaroline (MIC50/90, 0.25/0.5μg/mL) and 98% were susceptible to ceftobiprole (MIC50/90, 0.5/1μg/mL), regardless of their methicillin resistance. The two ceftobiprole-non-susceptible strains (including one MRSA) showed MICs at 4mg/L. Against CoNS isolates, ceftaroline and ceftobiprole exhibited in vitro potency with MIC50/90 values at 0.06/0.25μg/mL and 0.25/1μg/mL, respectively. At 4× MIC, ceftaroline and ceftobiprole showed rapid and marked bactericidal activity against both S. aureus and CoNS (after 24/12h and 12/6h of incubation, respectively), whilst none of the other molecules tested had a bactericidal effect by 24h.

CONCLUSIONS

This study showed that ceftaroline and ceftobiprole have excellent in vitro activity against clinical isolates of staphylococci involved in PJIs. These molecules may therefore represent promising alternatives for the treatment of such infections.

Changes in Antibiotic Susceptibility of Staphylococcus aureus Between the Stages of 2-Stage Revision Arthroplasty

BACKGROUND

Staphylococcus aureus is the predominant cause of periprosthetic joint infection (PJI) and can persist at the time of planned second stage of 2-stage revision arthroplasty, despite antibiotic cement spacer insertion and parenteral antibiotic therapy. Given the rapid emergence of antibiotic resistance, it is important to determine whether the antibiotic susceptibility of microorganisms changes between the stages of a 2-stage revision.

METHODS

A total of 1614 2-stage revision hip/knee arthroplasties performed for PJI at 2 academic institutions from 2000 to 2015 were identified. S aureus (methicillin susceptible and/or resistant) was isolated by culture in 402 (24.9%) cases during the first stage (resection arthroplasty). S aureus persisted and was cultured in 30 cases (knees = 18, hips = 12) during the second stage. Minimum inhibitory concentrations (MICs), demographics, antibiotic therapy, and surgical history were collected. The MICs at the time of the first-stage and second-stage surgeries were compared.

RESULTS

Nine (30%) revisions had an increase in vancomycin MIC. Six had an increase from ≤0.5 to 1 μg/mL, 2 had an increase from ≤0.5 to 2 μg/mL, and 1 had an increase from 1 to 2 μg/mL. All of the 9 revisions with an increase in vancomycin MIC had vancomycin in spacer.

CONCLUSION

Increases in the MICs were observed for vancomycin, the antibiotic widely used in cement spacers, in about one-third of the revisions. Despite the small sample size, the data from this preliminary study raise concern about the potential for emergence of resistant organisms between the stages of a 2-stage revision.

Human prosthetic joint infections are associated with myeloid-derived suppressor cells (MDSCs): Implications for infection persistence

Prosthetic joint infection (PJI) is a devastating complication of joint arthroplasty surgery typified by biofilm formation. Currently, mechanisms whereby biofilms persist and evade immune-mediated clearance in immune competent patients remain largely ill-defined. Therefore, the current study characterized leukocyte infiltrates and inflammatory mediator expression in tissues from patients with PJI compared to aseptic loosening. CD33⁺ HLA-DR^- CD66b⁺ CD14^-/low granulocytic myeloid-derived suppressor cells (G-MDSCs) were the predominant leukocyte population at sites of human PJI compared to aseptic tissues. MDSCs inhibit T cell proliferation, which coincided with reduced T cells in PJIs compared to aseptic tissues. IL-10, IL-6, and CXCL1 were significantly elevated in PJI tissues and have been implicated in MDSC inhibitory activity, expansion, and recruitment, respectively, which may account for their preferential increase in PJIs. This bias towards G-MDSC accumulation during human PJI could account for the chronicity of these infections by preventing the pro-inflammatory, antimicrobial actions of immune effector cells.

CLINICAL SIGNIFICANCE

Animal models of PJI have revealed a critical role for MDSCs and IL-10 in promoting infection persistence; however, whether this population is prevalent during human PJI and across distinct bacterial pathogens remains unknown. This study has identified that granulocytic-MDSC infiltrates are unique to human PJIs caused by distinct bacteria, which are not associated with aseptic loosening of prosthetic joints. Better defining the immune status of human PJIs could lead to novel immune-mediated approaches to facilitate PJI clearance in combination with conventional antibiotics. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1605-1613, 2018.

Comparison of Diagnostic Accuracy of Periprosthetic Tissue Culture in Blood Culture Bottles to That of Prosthesis Sonication Fluid Culture for Diagnosis of Prosthetic Joint Infection (PJI) by Use of Bayesian Latent Class Modeling and IDSA PJI Criteria for Classification

We have previously demonstrated that culturing periprosthetic tissue in blood culture bottles (BCBs) improves sensitivity compared to conventional agar and broth culture methods for diagnosis of prosthetic joint infection (PJI). We have also shown that prosthesis sonication culture improves sensitivity compared to periprosthetic tissue culture using conventional agar and broth methods. The purpose of this study was to compare the diagnostic accuracy of tissue culture in BCBs (subsequently referred to as tissue culture) to prosthesis sonication culture (subsequently referred to as sonicate fluid culture). We studied 229 subjects who underwent arthroplasty revision or resection surgery between March 2016 and October 2017 at Mayo Clinic in Rochester, Minnesota. Using the Infectious Diseases Society of America (IDSA) PJI diagnostic criteria (omitting culture criteria) as the gold standard, the sensitivity of tissue culture was similar to that of the sonicate fluid culture (66.4% versus 73.1%, P = 0.07) but was significantly lower than that of the two tests combined (66.4% versus 76.9%, P < 0.001). Using Bayesian latent class modeling, which assumes no gold standard for PJI diagnosis, the sensitivity of tissue culture was slightly lower than that of sonicate fluid culture (86.3% versus 88.7%) and much lower than that of the two tests combined (86.3% versus 99.1%). In conclusion, tissue culture in BCBs reached sensitivity similar to that of prosthesis sonicate fluid culture for diagnosis of PJI, but the two tests combined had the highest sensitivity without compromising specificity. The combination of tissue culture in BCBs and sonicate fluid culture is recommended to achieve the highest level of microbiological diagnosis of PJI.

Prosthetic Joint Infections: an Update

PURPOSE OF REVIEW

Prosthetic joint infection (PJI) is a rare but serious complication that is frequently misdiagnosed. We aimed to highlight the nuances of PJI diagnosis and antimicrobial therapies and provide clarity in key areas of management.

RECENT FINDINGS

Current research in PJI centers on a potential role for diagnostic biomarkers, molecular techniques, and implant sonication to reduce culture-negativity rates. The optimal duration of antimicrobial therapy remains controversial. A high clinical index of suspicion for PJI combined with data from multiple preoperative and intraoperative tests enables timely diagnosis and treatment. Biomarkers, molecular methods, and implant sonication are currently adjunctive to traditional diagnostic techniques. Shorter courses of antimicrobial therapies as well as the role of chronic suppressive therapy need confirmation by randomized controlled trials. Existing practices for preoperative dental prophylaxis and treatment of asymptomatic bacteriuria warrant revision based on evidence arguing against risk for PJI.

In vitro activity of oritavancin against biofilms of staphylococci isolated from prosthetic joint infection

We tested the in vitro activity of oritavancin against 185 staphylococci associated with prosthetic joint infection, including 37 methicillin-resistant S. aureus, 67 methicillin-susceptible S. aureus, 59 methicillin-resistant S. epidermidis (MRSE), and 22 methicillin-susceptible S. epidermidis (MSSE) isolates. The oritavancin MIC₅₀ for S. aureus and MSSE was 0.03 μg/mL, and for MRSE, it was 0.06 μg/mL; MIC₉₀ for S. aureus and S. epidermidis was 0.12 μg/mL for both the methicillin-resistant and -susceptible subgroups. The oritavancin MBBC₅₀ for S. aureus and S. epidermidis was 2 μg/mL for both the methicillin-resistant and -susceptible subgroups; the MBBC₉₀ for S. aureus and MSSE was 4 μg/mL, and for MRSE, it was 8 μg/mL.

Septic Arthritis and Prosthetic Joint Infections in Older Adults

Older adults are at increased risk for septic arthritis and prosthetic joint infections (PJI), owing at least in part to comorbid conditions and frailty. An increasing number of older adults undergo total joint arthroplasty to improve their quality of life. Infections in older adults differ from younger populations by the causative organisms, a great proportion of which are Staphylococcal infections. Targeting important modifiable and nonmodifiable risk factors may prevent or reduce the burden of joint infections in older adults. This review summarizes the epidemiology, pathogenesis, clinical manifestations, diagnosis, management, and prevention of septic arthritis and PJI in older adults.

Alpha Defensin Lateral Flow Test for Diagnosis of Periprosthetic Joint Infection: Not a Screening but a Confirmatory Test

BACKGROUND

Determination of alpha defensin in synovial fluid has shown promising results for diagnosing periprosthetic joint infection (PJI). The purposes of our study were to assess the performance of alpha defensin lateral flow (ADLF) test for the diagnosis of acute and chronic PJI using 3 classification systems and to compare its performance with the synovial fluid leukocyte count.

METHODS

Patients in whom aspiration of a prosthetic hip or knee joint was performed before revision arthroplasty were prospectively included. In addition to standard diagnostic tests, the ADLF test was performed in synovial fluid. Patients were classified as having PJI or aseptic failure according to the definition criteria of the Musculoskeletal Infection Society (MSIS), the Infectious Diseases Society of America (IDSA), and the proposed criteria of the European Bone and Joint Infection Society (EBJIS). The performance of the ADLF test and the leukocyte count was compared using the McNemar chi-square test.

RESULTS

Of 212 included patients, 151 (71%) had a knee prosthesis and 61 (29%) had a hip prosthesis. PJI was diagnosed in 45 patients (21%) using the MSIS criteria, in 55 patients (26%) using the IDSA criteria and in 79 patients (37%) using the proposed EBJIS criteria. The sensitivity of the ADLF test was 84% (95% confidence interval [CI], 71% to 94%) with the MSIS criteria, 67% (95% CI, 53% to 79%) with the IDSA criteria, and 54% (95% CI, 43% to 66%) with the proposed EBJIS criteria. The ADLF test showed high specificity using all classification criteria (96% to 99%) and represented the most specific preoperative test for PJI, especially in the early postoperative period (91%; 95% CI, 59% to 100%). Using the proposed EBJIS definition criteria, the sensitivity of the leukocyte count was significantly higher than that of the ADLF test (86% [95% CI, 76% to 93%] compared with 54% [95% CI, 43% to 66%]; p < 0.001), particularly in chronic PJI (81% compared with 44%, respectively; p < 0.001).

CONCLUSIONS

The ADLF test was rapid and highly specific for diagnosing PJI (>95%). However, its sensitivity was limited (54% to 84%) and it should therefore not be used for screening, but rather as a confirmatory test for PJI.

LEVEL OF EVIDENCE

Diagnostic Level I. See Instructions for Authors for a complete description of levels of evidence.

Comparison with the osteoconductivity and bone-bonding ability of the iodine supported titanium, titanium with porous oxide layer and the titanium alloy in the rabbit model

BACKGROUND

One of the serious postoperative complications associated with joint replacement is bacterial infection. In our recent investigations, iodine supported titanium implants demonstrated antibacterial activity in both in vitro and in vivo studies. The surfaces of the implants have porous anodic oxide layer with the antiseptic properties of iodine. According to the literature the titanium with porous anodic oxide have good osteoconductivity. But it is not clear whether the properties of iodine influence bone bonding of implants.

OBJECTIVES

The aim of this study is to evaluate the influence of the properties of iodine and porous anodic oxide layer in the bone bonding ability of titanium implants.

STUDY DESIGN & METHODS

Titanium rods were implanted in intramedullary rabbit femur models, in regard to the cementless hip stem. The implant rods were 5 mm in diameter and 25 mm in length. Three types of titanium rods were implanted.One was untreated titanium (control group (CL)), another was titanium with oxide layer without iodine (oxide layer group (OL)), and the other was Iodine treated Titanium (iodine group (ID)). The rods were inserted into the distal femur. We assessed the bonding strength by a measuring pull-out test at 4, 8, and 12 weeks after implantation. The bone-implant interfaces were evaluated at 4 weeks after implantation.

RESULTS

Pull-out test results of the ID implants were 202, 355, and 344 N, and those of the OL implants were 220, 310, 329 N at 4, 8, and 12 weeks, significantly higher than those of the CL implants (102, 216, and 227 N). But there were no significant difference in ID implants and OL implants. Histological examination revealed that new bone formed on the surface of each types of implants, but significantly more bone made direct contact with the surfaces of the ID implants and OL implants.

CONCLUSIONS

This research showed that new type of coating, iodine coated titanium has low toxicity and good osteoconductivity.

Molecularly specific detection of bacterial lipoteichoic acid for diagnosis of prosthetic joint infection of the bone

Discriminating sterile inflammation from infection, especially in cases of aseptic loosening versus an actual prosthetic joint infection, is challenging and has significant treatment implications. Our goal was to evaluate a novel human monoclonal antibody (mAb) probe directed against the Gram-positive bacterial surface molecule lipoteichoic acid (LTA). Specificity and affinity were assessed in vitro. We then radiolabeled the anti-LTA mAb and evaluated its effectiveness as a diagnostic imaging tool for detecting infection via immunoPET imaging in an in vivo mouse model of prosthetic joint infection (PJI). In vitro and ex vivo binding of the anti-LTA mAb to pathogenic bacteria was measured with Octet, ELISA, and flow cytometry. The in vivo PJI mouse model was assessed using traditional imaging modalities, including positron emission tomography (PET) with [¹⁸F]FDG and [¹⁸F]NaF as well as X-ray computed tomography (CT), before being evaluated with the zirconium-89-labeled antibody specific for LTA ([⁸⁹Zr]SAC55). The anti-LTA mAb exhibited specific binding in vitro to LTA-expressing bacteria. Results from imaging showed that our model could reliably simulate infection at the surgical site by bioluminescent imaging, conventional PET tracer imaging, and bone morphological changes by CT. One day following injection of both the radiolabeled anti-LTA and isotype control antibodies, the anti-LTA antibody demonstrated significantly greater (P < 0.05) uptake at S. aureus-infected prosthesis sites over either the same antibody at sterile prosthesis sites or of control non-specific antibody at infected prosthesis sites. Taken together, the radiolabeled anti-LTA mAb, [⁸⁹Zr]SAC55, may serve as a valuable diagnostic molecular imaging probe to help distinguish between sterile inflammation and infection in the setting of PJI. Future studies are needed to determine whether these findings will translate to human PJI.

A new imaging technique distinguishes bacterial infection at the site of joint implants from less-serious postoperative inflammation, saving patients from unnecessary and invasive treatments. Daniel Thorek of Johns Hopkins University School of Medicine and colleagues used an antibody that binds to lipoteichoic acid on the cell wall of Staphylococcus bacteria to detect infection at joint implant sites. The antibody was labeled with a radioactive agent and injected into mice that simulated infection of a knee replacement site. A PET scan conducted 1 day after antibody injection showed that it gathered at the infected joint significantly more than it did at the uninfected implant sites in other mice. This method could improve the diagnosis of joint implant infection, which necessitates removal of the prosthetic and all infected tissues, followed by prolonged antibiotic therapy.

Suspected periprosthetic joint infection after total knee arthroplasty under propofol versus sevoflurane anesthesia: a retrospective cohort study

PURPOSE

Periprosthetic joint infection is a serious complication of total knee arthroplasty. Though there are many factors that might increase its risk, the use of propofol for maintaining general anesthesia could theoretically increase the incidence of infection because of its lipid component that supports bacterial growth. Nevertheless, the relationship between anesthetic maintenance agents and the occurrence of periprosthetic joint infection remains uncertain. The purpose of this study was to compare the incidence of suspected early-onset periprosthetic joint infection between patients undergoing total knee arthroplasty under propofol vs sevoflurane anesthesia.

METHODS

We conducted a retrospective cohort study of patients in the national inpatient Diagnosis Procedure Combination database in Japan who underwent total knee arthroplasty. Suspected periprosthetic joint infection was surrogately defined as the need for arthrocentesis or debridement within 30 days of surgery. Propensity score matching was performed between patients who received either propofol or sevoflurane for anesthetic maintenance to determine the proportion of those with infection.

RESULTS

Eligible patients (n = 21,899) were categorized into either the propofol (n = 7,439) or sevoflurane (n = 14,460) groups. In the 5,140 propensity-matched patient pairs, there was no significant difference in the proportion of arthrocentesis or debridement [1.3% propofol vs 1.7% sevoflurane; respectively (relative risk, 0.76; 95% CI, 0.55 to 1.04; P = 0.10)] between the groups. The mean (SD) length of stay in the propofol group was significantly longer than in the sevoflurane group [32.5 (18.4) days vs 31.4 (14.4) days, respectively; mean difference, 1.1; 95% CI, 0.5 to 1.8; P < 0.001].

CONCLUSION

Propensity score analysis suggested no significant association between the choice of anesthetic maintenance agent and the occurrence of suspected early-onset periprosthetic joint infection in patients undergoing total knee arthroplasty.

Current review-The rise of bacteriophage as a unique therapeutic platform in treating peri-prosthetic joint infections

Peri-prosthetic joint infection (PJI) is one of the most serious and dreaded complications after total joint replacement (TJR). Due to an aging population and the constant rise in demand for TJR, the incidence of PJI is also increasing. Successful treatment of PJI is challenging and is associated with high failure rates. One of the main causes for treatment failure is bacterial biofilm formation on implant surfaces and the adherence of biofilm bacteria on tissue and bone next to the implant. Biofilms are protective shields to bacterial cells and possess many unique properties that leads to antibiotic resistance. New therapeutic platforms are currently being explored to breakdown biofilm matrix in order to enhance the efficacy of antibiotics. Bacteriophages (phages) is one of these unique therapeutic platforms that can degrade biofilms as well as target the killing of bacterial cells. Preclinical studies of biofilm-mediated infections have demonstrated the ability of phage to eradicate biofilms and clear infections by working synergistically with antibiotics. There is strong preclinical evidence that phage can reduce the concentration of antibiotics required to treat an infection. These findings support a promising role for phages as a future clinical adjunct to antibiotics. In addition, phage therapy can be personalized to target a specific bacterial strain. Clinical studies using phage therapy are limited in Western literature; but phase I studies have established good safety profile with no adverse outcomes reported. In order to translate phage therapy to treat PJI in clinics, further preclinical testing is still required to study optimal delivery methods as well as the interaction between phage and the immune system in vivo. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1051-1060, 2018.

Long-term outcomes after infected mini-open rotator cuff repair: results of a 10-year review

BACKGROUND

Infection after rotator cuff repair (RCR) is uncommon. There are few reports in the literature regarding the management and long-term results of patients in whom deep infection of the shoulder develops after RCR. The objective of this study was to assess the long-term clinical and radiologic outcomes of these patients.

METHODS

We retrospectively reviewed a consecutive series of 764 patients after mini-open RCR in which 9 patients had postoperative infection. The demographic data, clinical and laboratory findings, risk factors, bacteriologic findings, and results of surgical management were analyzed. All patients underwent clinical and radiologic assessment at long-term follow-up of approximately 10 years after infection.

RESULTS

The mean age of the patients was 56.2 years. The mean time to presentation for infection after RCR was 16 days. All patients had pain on presentation, and 6 patients had persistent discharge from their wounds with erythema. The most common organism was Staphylococcus aureus. At final follow-up at a mean of 11.62 years after surgery, the mean Simple Shoulder Test score was 10.5 and the mean Constant score was 70. The rotator cuff was intact in 5 of 7 patients.

CONCLUSION

With appropriate treatment, eradication of infection can be achieved, and in appropriate cases, anchors can be retained. Reasonable long-term functional outcome scores can be achieved.

Fabrication of hyaluronidase-responsive biocompatible multilayers on BMP2 loaded titanium nanotube for the bacterial infection prevention

Infection associated with orthopedic implants is the chief cause of implant failure. An important consideration to prevent the infection at implants is to inhibit the biofilm formation for the initial 6 h. Therefore, we fabricated hyaluronidase-sensitive multilayers of chitosan (Chi)/sodium hyaluronate-lauric acid (SL) onto the surface of bone morphogenetic protein 2 (BMP2) loaded titanium nanotube (TNT) via spin-assisted layer-by-layer technique. The results of both Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (¹H NMR) confirmed the successful synthesis of SL. The multilayer structure on BMP2 loaded TNT was characterized by field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and water contact angle, respectively. The release profiles confirmed that hyaluronidase could trigger the release of lauric acid (LA) from the SL multilayer and accelerate the release of BMP2 in the system. The hyaluronidase-sensitive-multilayer-coated BMP2-loaded TNT (TNT/BMP2/(Chi/SL/Chi/Gel)₄) not only demonstrated good antibacterial capability, but also showed good biocompatibility in in vitro usage, which was supported by the efficient growth inhibition of both Staphylococcus aureus and Escherichia coli, as well as higher cell viability, alkaline phosphatase activity, mineralization capability, and higher gene expression of osteoblasts on TNT/BMP2/(Chi/SL/Chi/Gel)₄. This study developed an alternative approach to fabricate effective antibacterial implants for orthopedic implantation.

Effect of an exfoliating skincare regimen on the numbers of epithelial squames on the skin of operating theatre staff, studied by surface microscopy

BACKGROUND

The shedding of epithelial squames (skin scales) by staff in operating theatre air is an important source of deep infection following joint replacement surgery. This is a serious complication, resulting in significant morbidity for the patient and substantial cost implications for healthcare systems. Much effort has been put into providing clean air in operating theatres, yet little attention has been given to reducing the shedding of surface skin scales at source.

AIM

To develop a novel method for calculating surface skin scale density using surface microscopy, and to use it to evaluate the effect of a skincare regimen on operating theatre staff.

METHODS

Surface microscopy with Z-stacked imaging was used to visualize the effect of a skincare regimen involving three stages: washing with soap; exfoliation; and application of emollient. A USB microscope was then used in a field study to take images of the skin of operating theatre staff who applied the regimen to one lower limb the night before testing. The other limb was used as a control. Two blinded assessors analysed scale density.

RESULTS

Z-stack images from the surface microscope enabled observations of the skincare regimen. The USB microscope also provided adequate images that enabled assessment of skin scale density. In the operating theatre staff, a 72.1% reduction in visible skin scales was observed following application of the skincare regimen.

CONCLUSIONS

Further work is required to demonstrate how this effect correlates with dispersion of skin particles in a cleanroom, and subsequently in live operating theatre studies.

In vitro activity of oritavancin against planktonic and biofilm states of vancomycin-susceptible and vancomycin-resistant enterococci

We tested the in vitro activity of oritavancin against 60 vancomycin-susceptible enterococci (VSE) and 27 vancomycin-resistant enterococci (VRE). The oritavancin MIC ranged from ≤0.002 to 0.5μg/mL; the minimum biofilm bactericidal concentration ranged from ≤0.002 to 2μg/mL. Oritavancin has promising in vitro activity against VSE and VRE in both planktonic and biofilm states.

Health-related quality of life with long-term retention of the PROSthesis of Antibiotic Loaded Acrylic Cement system following infection resolution in low demand patients

BACKGROUND

The study purpose was to (1) evaluate health-related quality of life (HRQL) with the PROSthesis of Antibiotic Loaded Acrylic Cement (PROSTALAC) in situ for infected total hip arthroplasty (THA), (2) determine infection resolution, and (3) compare subjects who underwent second stage surgery with those who retained the PROSTALAC on a longer term basis.

METHODS

Demographics, physical demand level, and comorbidities were recorded prospectively in 29 subjects followed to at least 24 months after initial PROSTALAC insertion. HRQL was evaluated using the Western Ontario McMaster Osteoarthritis Index (WOMAC) and RAND 36-Item Health Survey. Infection resolution was determined using a pre-specified clinical definition.

RESULTS

Twenty-five of 29 (86%) subjects' infections resolved. Three subjects died, of whom two had resolved infections. For survivors, 22/26 (85%) completed HRQL evaluations. After PROSTALAC insertion, pain and function improved within 3-6 months and was retained at 24 months. Of those followed to 24 months, 7/22 (32%) subjects underwent second stage surgery. They were higher physical demand subjects ( p = 0.03) than those not undergoing second stage surgery. We found no difference in WOMAC scores at 24 months between those who underwent second stage surgery and those who retained the PROSTALAC ( p > 0.32).

DISCUSSION

The PROSTALAC system for THA appears to allow acceptable HRQL while in situ for at least 2 years in low physical demand patients. Subjects with higher physical demand levels are more likely to undergo second stage surgery.

CONCLUSION

Further evaluation is required to determine whether longer term PROSTALAC retention may be appropriate for specific patient groups.

Temperature-sensitive liposomal ciprofloxacin for the treatment of biofilm on infected metal implants using alternating magnetic fields

Implants are commonly used as a replacement for damaged tissue. Many implants, such as pacemakers, chronic electrode implants, bone screws, and prosthetic joints, are made of or contain metal. Infections are one of the difficult to treat complications associated with metal implants due to the formation of biofilm, a thick aggregate of extracellular polymeric substances (EPS) produced by the bacteria. In this study, we treated a metal prosthesis infection model using a combination of ciprofloxacin-loaded temperature-sensitive liposomes (TSL) and alternating magnetic fields (AMF). AMF heating is used to disrupt the biofilm and release the ciprofloxacin-loaded TSL. The three main objectives of this study were to (1) investigate low- and high-temperature-sensitive liposomes (LTSLs and HTSLs) containing the antimicrobial agent ciprofloxacin for temperature-mediated antibiotic release, (2) characterise in vitro ciprofloxacin release and stability and (3) study the efficacy of combining liposomal ciprofloxacin with AMF against Pseudomonas aeruginosa biofilms grown on metal washers. The release of ciprofloxacin from LTSL and HTSL was assessed in physiological buffers. Results demonstrated a lower transition temperature for both LTSL and HTSL formulations when incubated in serum as compared with PBS, with a more pronounced impact on the HTSLs. Upon combining AMF with temperature-sensitive liposomal ciprofloxacin, a 3 log reduction in CFU of Pseudomonas aeruginosa in biofilm was observed. Our initial studies suggest that AMF exposure on metal implants can trigger release of antibiotic from temperature sensitive liposomes for a potent bactericidal effect on biofilm.

Operating Room Traffic Increases Aerosolized Particles and Compromises the Air Quality: A Simulated Study

BACKGROUND

Strategies to prevent bacterial fallout and reduce particle count in the operating room (OR) are key components of preventing periprosthetic joint infection. Although OR traffic control is an important factor, a quantitative study has not been performed to investigate the influence of personnel and door opening on OR air quality. This simulated study aimed to examine the influence of these 2 factors on particle density in OR with and without the laminar air flow (LAF).

METHODS

Both experiments took place within an empty OR of an arthroplasty unit equipped with an LAF system. First, the number of particles in the air was counted using a particle counting apparatus while 9 persons entered the room, one every 15 minutes. Second, the door was opened and closed starting with zero door openings per minute and increasing to 4 in 15-minute increments. Both experiments were performed once with the LAF turned on and once without.

RESULTS

The number of personnel in the OR and the number of door openings per minute correlate with the density of particles. Both relationships were significantly reduced by turning the LAF on (correlation coefficients <0.4). With the LAF being turned on, the particle density per person decreased from 211.19 to 18.19 particles/ft³ (P < .001) and the particle density per rate of door openings declined from 117.80 to 1.90 particles/ft³ (P = .017).

CONCLUSION

This study confirms that personnel and door opening are a major source of particles in the OR air. Controlling traffic is critical for reduction of particles and is likely to be a key preventative strategy in reducing periprosthetic joint infection. LAF is protective against the negative influence of number of people and door openings.

Perioperative Allogeneic Red Blood-Cell Transfusion Associated with Surgical Site Infection After Total Hip and Knee Arthroplasty

BACKGROUND

Perioperative allogeneic red blood-cell transfusion is a suspected risk factor for surgical site infection (SSI) after total joint arthroplasty (TJA), but the interrelationships among SSI risk, transfusion dose, preoperative anemia, and the presence of coagulopathies have not been well described.

METHODS

Data on SSI within 1 year after surgery as well as on transfusion with blood products within 30 days after surgery were obtained for 6,788 patients who had undergone primary or revision total hip or knee arthroplasty from 2000 to 2011 in a single hospital system. Multivariate logistic regression modeling was used to determine the independent association between allogeneic red blood-cell transfusion and SSI.

RESULTS

There was a dose-dependent association between allogeneic red blood-cell transfusion and SSI, with the infection rate increasing as the transfusion dose increased from 1 unit (odds ratio [OR] = 1.97; 95% confidence interval [CI] = 1.38, 2.79; p < 0.001), to 2 units (OR = 2.20; CI = 1.37, 3.44; p = 0.002), to 3 units (OR = 3.66; CI = 1.72, 7.16; p = 0.001), and to >3 units (OR = 7.40; CI = 4.91, 11.03; p < 0.001) after controlling for medical comorbidities, planned procedure, preoperative anemia, and preexisting coagulopathies. A preexisting bleeding disorder (OR = 2.09; CI = 1.57, 2.80; p < 0.001) and clotting disorder (OR = 1.37; CI = 1.14, 1.64; p = 0.001) and preoperative anemia (OR = 3.90; CI = 3.31, 4.61; p < 0.001) were all independent risk factors for transfusion after adjusting for the planned procedure.

CONCLUSIONS

We found a dose-dependent relationship between allogeneic red blood-cell transfusion and SSI risk after total hip or knee arthroplasty. Additionally, preoperative anemia or a known bleeding or clotting disorder were risk factors for the need for allogeneic red blood-cell transfusion. Our findings underscore the need for preoperative risk assessment, methods to limit surgical tissue injury, and optimized blood conservation strategies.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Does Treatment Order Matter? Investigating the Ability of Bacteriophage to Augment Antibiotic Activity against Staphylococcus aureus Biofilms

The inability to effectively treat biofilm-related infections is a major clinical challenge. This has been attributed to the heightened antibiotic tolerance conferred to bacterial cells embedded within biofilms. Lytic bacteriophages (phages) have evolved to effectively infect and eradicate biofilm-associated cells. The current study was designed to investigate the ability of phage treatment to enhance the activity of antibiotics against biofilm-forming Staphylococcus aureus. The biofilm positive S. aureus strain ATCC 35556, the lytic S. aureus phage SATA-8505, and five antibiotics (cefazolin, vancomycin, dicloxacillin, tetracycline, and linezolid), used to treat S. aureus infections, were tested in this study. The ability of the SATA-8505 phage to augment the effect of these antibiotics against biofilm-associated S. aureus cells was assessed by exposing them to one of the five following treatment strategies: (i) antibiotics alone, (ii) phage alone, (iii) a combination of the two treatments simultaneously, (iv) staggered exposure to the phage followed by antibiotics, and (v) staggered exposure to antibiotics followed by exposure to phage. The effect of each treatment strategy on biofilm cells was assessed by enumerating viable bacterial cells. The results demonstrate that the treatment of biofilms with either SATA-8505, antibiotics, or both simultaneously resulted in minimal reduction of viable biofilm-associated cells. However, a significant reduction [up to 3 log colony forming unit (CFU)/mL] was observed when the phage treatment preceded antibiotics. This effect was most pronounced with vancomycin and cefazolin which exhibited synergistic interactions with SATA-8505, particularly at lower antibiotic concentrations. This in vitro study provides proof of principle for the ability of phages to augment the activity of antibiotics against S. aureus biofilms. Our results also demonstrate that therapeutic outcomes can be influenced by the sequence in which these therapeutic agents are administered, and the nature of their interactions. Further investigation into the interactions between lytic phages and antibiotics against various biofilm-forming organisms is important to direct future clinical translation of efficacious antibiotic–phage combination therapeutic strategies.

Analysis of postoperative and hematogenous prosthetic joint-infection microbiological patterns in a large cohort

OBJECTIVES

This study was undertaken to analyze prosthetic joint infection (PJI)-causing microorganisms and compare their distribution patterns according to PJI classification.

METHODS

Cohort study from a single referral center for bone-and-joint infections from January 2004 to December 2015.

RESULTS

Nine hundred and twenty-six patients, who developed 997 PJIs, involving the hip (62%), knee (35%) and/or shoulder (1%), were included. PJIs were classified as early postoperative (19%), late chronic (30%), hematogenous (35%) and undetermined (16%). Pathogens most frequently isolated from early-postoperative PJIs were staphylococci (57%), with 25% each Staphylococcus aureus or Staphylococcus epidermidis; 21% were polymicrobial and 10% Gram-negative rods. For late-chronic PJIs, the most frequent microbes were staphylococci (61%), predominantly S. epidermidis (35%); anaerobic bacteria were isolated from 15%; 11% were polymicrobial. Hematogenous PJIs were 99% monomicrobial. Although S. aureus was the most frequently isolated species (28%), streptococci were isolated slightly more often than staphylococci (39% vs. 36%). Among streptococci, group B streptococci were the most frequent (15%). The portal of entry was identified for 52% of hematogenous PJIs: 15% cutaneous, 11% dental, 9% gastrointestinal, 6% urinary, and 11% miscellaneous.

CONCLUSION

Although a wide variety of microorganisms was isolated from PJIs, specific microbiological patterns were observed according to infection classification.

Revision Total Knee Arthroplasty for Periprosthetic Joint Infection Is Associated With Increased Postoperative Morbidity and Mortality Relative to Noninfectious Revisions

BACKGROUND

Periprosthetic joint infection (PJI) after primary total knee arthroplasty (TKA) is a devastating complication. The short-term morbidity profile of revision TKA performed for PJI relative to non-PJI revisions is poorly characterized. The purpose of this study is to determine 30-day postoperative outcomes after revision TKA for PJI, relative to primary TKA and aseptic revision TKA.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program from 2005 to 2015 was queried for primary and revision TKA cases. Revision TKA cases were categorized into PJI and non-PJI cohorts. Differences in 30-day outcomes including postoperative complications, readmissions, operative time, and length of stay were compared using bivariate and multivariate analyses.

RESULTS

In total, 175,761 TKAs were included in this study, with 162,981 (92.7%) primary TKAs and 12,780 (7.3%) revision TKAs, of which 2196 (17.2%) revisions were performed for PJI. When compared to aseptic revision TKA, multivariate analysis demonstrated that PJI revisions had a significantly higher risk of major early postoperative complications including death (adjusted odds ratio [OR] 3.25) and sepsis (OR 8.73). In addition, nonhome discharge (OR 1.75), readmissions (OR 1.67), and length of stay (+2.1 days) were all greater relative to non-PJI revisions.

CONCLUSION

Utilizing a large, prospectively collected, national database, we found that revision TKA for PJI has a greater risk of short-term morbidity and mortality and requires a higher utilization of healthcare resources. These results have implications for patient counseling and alternative payment models that may eventually include revision TKA.

Periprosthetic joint infection caused by anaerobes. Retrospective analysis reveals no need for prolonged cultivation time if sensitive supplemented growth media are used

BACKGROUND

In microbiological diagnosis of periprosthetic joint infection (PJI) culture media and incubation time are controversially discussed, especially if anaerobic bacteria are the causative agent. This study was conducted to demonstrate the influence of sensitive supplemented growth media on the duration of culturing anaerobes.

METHODS

Twenty-five consecutive cases were included in this retrospective study. For definition of PJI, the criteria of the Musculoskeletal Infection Society (MSIS) were considered. Histopathological analysis was interpreted according to the classification by Krenn et al. The quantity and time to positivity of detected anaerobes were monitored. Furthermore, antimicrobial activity within the tissue and sonicate fluid was phenotypically tested.

RESULTS

In all cases, even if the patients had received antibiotics before recovery, culture of anaerobes (Propionibacterium species, Finegoldia magna, Parvimonas micra and Robinsoniella peoriensis), both from tissue samples and prosthetic components, first became detectable in supplemented liver thioglycollate broth within six days (median: four days).

CONCLUSION

Recommendations for prolonged cultivation for up to 14 days mostly aim at detection of anaerobes. Here we present a laboratory procedure that can shorten cultivation time considerably.

Two-step biocompatible surface functionalization for two-pathway antimicrobial action against Gram-positive bacteria

The use of indwelling devices has emerged as a frequent and often life-saving medical procedure. However, infection in prosthetic surgery is one of the most important and devastating complications. Once the biofilm has been formed, its eradication is extremely difficult, due to an increased resistance to host defense and conventional antimicrobials. Thus, the design of novel strategies for inhibiting the bacterial adhesion on implantable devices is a key point for successful surgical procedures. In this work, the development of a simple two-step protocol to prepare surfaces able to prevent the bacterial growth was successfully achieved. The surface-modification design includes a combined approach involving the multi-functionalization of Ti surfaces with silver nanoparticles (AgNPs) and/or ampicillin (AMP). The surface chemistry involved in AMP adsorption on titanium and silver surfaces was elucidated for the first time, thus establishing the basis for the further anchoring of other antibacterial compounds having similar functional groups. Our results show that the antibiotic binds to the titanium surface through covalent interactions between the COOH groups in AMP and the OH groups of the native TiO₂ on the surface, although electrostatic interactions between protonated AMP and negatively charged TiO₂ can also contribute to the antibiotic anchoring to the surface. The AMP immobilization on the AgNPs is carried out by thiolate-like bonds. The β-lactam ring functionality is preserved after the adsorption process, since the Ti-AgNPs-AMP surface was able to decrease the bacterial viability in more than 80%. Moreover, the antimicrobial capacity is maintained over time due to a two-pathway antibacterial mechanism: death by contact (AMP) and death by release (AgNPs). The effect of AMP prevails on AgNPs at early stages of bacterial adhesion, while AgNPs are responsible for sustaining the relatively low but steady release of Ag(I), preserving the bacteriostatic activity of the surface over time. This effect would contribute to prevent infections due to sessile cells on indwelling devices, powering the action of the immune system and the conventional antibiotics usually dosed in implanted patients.

Evaluation of the antimicrobial activity and cytotoxic effect of hydroxyapatite containing Brazilian propolis

The aim of this work was to produce hydroxyapatite powder (HA) containing the dry extract of green and red propolis, and to evaluate the possible bactericidal activity of these materials over a short period of time through a fast release system. The ethanolic extracts of green and red propolis (EEP) were incorporated into the material by spray drying. After release tests, powders containing dry EEP were characterized regarding the content of total phenolics and flavonoids. Material characterization was undertaken by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The antimicrobial activity was evaluated by plate colony counting, minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) against Staphylococcus aureus (S. aureus). The cytotoxicity of the materials was determined by the neutral red incorporation method. The materials showed apparently spherical morphology, indicating a decrease in the degree of agglomeration with the addition of propolis. Characteristic HA and propolis functional groups were observed in the FTIR. The materials showed a higher release of phenolics and lower amounts of flavonoids when compared to the EEP, with the higher amounts of flavonoids observed for HA with red propolis. A bactericidal effect was observed for all materials within the interval of 0.5 and 1 h, showing lower inhibitory activity (MIC) and higher bactericidal activity (MBC) when compared to the EEP, with the best results attributed to HA with red propolis. The IC₅₀ values (which is the concentration needed to inhibit cell growth by 50%) obtained from the cytotoxicity assay for HA with the green and red propolis lay between MIC and MCB. Considering these results, it is suggested that HA and propolis may be used as a possible antimicrobial agent, inhibiting the growth of S. aureus, although further in vivo biocompatibility should be investigated before using this material as a medical device with bactericidal potential.

Diagnosis of Prosthetic Joint Infection: Cultures, Biomarker and Criteria

Prosthetic joint infections (PJIs) are devastating complications after joint arthroplasty that continue to pose a diagnostic challenge. Currently, a single, stand-alone test with the adequate accuracy and reliability for diagnosis of PJI is not available; therefore, physicians who care for patients with PJI must rely on a combination of diagnostic tests for the diagnosis of PJI. This article reviews conventional laboratory test modalities, diagnostic accuracy and limitations of current tests, and novel emerging tests for the diagnosis of PJI.

Fungal Musculoskeletal Infections

Fungi are rare but important causes of osteoarticular infections, and can be caused by a wide array of yeasts and molds. Symptoms are often subacute and mimic those of other more common causes of osteoarticular infection, which can lead to substantial delays in treatment. A high index of suspicion is required to establish the diagnosis. The severity of infection depends on the inherent pathogenicity of the fungi, the immune status of the host, the anatomic location of the infection, and whether the infection involves a foreign body. Treatment often involves a combination of surgical debridement and prolonged antifungal therapy.

A Real Pain: Diagnostic Quandaries and Septic Arthritis

Rapid diagnosis and treatment of an infected joint are paramount in preserving orthopedic function. Here, we present a brief review of the many challenges associated with the diagnosis of both septic arthritis and prosthetic joint infections. We also discuss the many laboratory tests currently available to aid in the accurate diagnosis of joint infection, as well as emerging diagnostics that may have future utility in the diagnosis of these challenging clinical entities.

Does Use of Lidocaine Affect Culture of Synovial Fluid Obtained to Diagnose Periprosthetic Joint Infection (PJI)? An In Vitro Study

Background

Synovial fluid culture (SFC) is recommended as one of the major diagnostic criteria by the Musculoskeletal Infection Society (MSIS) for diagnosing periprosthetic joint infection (PJI). Local anesthetic agents are used for anesthesia and analgesia in some clinical settings to relieve pain. As a local anesthetic, lidocaine is safely used in arthrocentesis to obtain synovial fluid. The goal of this study was to determine if infiltration anesthesia with additive-free lidocaine 2% has antibacterial effects that might interfere with subsequent SFC.

Material/Methods

Eight isolates of reference strains of Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus hominis, Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Streptococcus pyogenes, and Candida albicans were incubated on the plates. Each bacterial suspension was formed by 50-fold dilution before the test lidocaine 2% was added. For each strain, bacterial suspension was divided into 2 groups (5 samples each) exposed either lidocaine 2% or sterile non-bacteriostatic 0.45% saline. The antimicrobial property of lidocaine 2% was determined by measuring the bacterial density on agar plates incubated for 24 h and comparing it with controls unexposed to lidocaine 2%.

Results

Exposure to lidocaine 2% negatively affected microbial viability in vitro. Of the lidocaine 2% exposure, reference strains but no Streptococcus pyogenes strain resulted in fewer colony-forming units compared with the sterile saline control. The antibacterial property of lidocaine 2% appears to affect the ability to culture the organism in synovial fluid.

Conclusions

Lidocaine 2% has strong antimicrobial activities against some commonly encountered bacterial strains in PJI. As a result, infiltration anesthesia with additive-free lidocaine 2% before the arthrocentesis procedure may affect the results of SFC. To further evaluate its potential antibacterial usefulness in clinical applications, studies are needed to assess the ability of lidocaine to reduce the risk of iatrogenic infections.

Lower activation of caspase-1 by Staphylococcus epidermidis isolated from prosthetic joint infections compared to commensals

Nosocomial sequence types of Staphylococcus epidermidis dominate in prosthetic joint infections. We examined caspase-1 activation in human neutrophils after incubation with Staphylococcus epidermidis isolated from prosthetic joint infections and normal skin flora. Active caspase-1 was lower after incubation with isolates from prosthetic joint infections than after incubation with commensal isolates. Both host and isolate dependent differences in active caspase-1 were noted. Our results indicate that there might be a host-dependent incapacity to elicit a strong caspase-1 response towards certain strains of S. epidermidis. Further experiments with a larger number of individuals are warranted.

Staphylococcus epidermidis isolates from nares and prosthetic joint infections are mupirocin susceptible

The objective of the present study was to investigate the antibiotic susceptibility including mupirocin among Staphylococcus. epidermidis isolated from prosthetic joint infections (PJIs) (n=183) and nasal isolates (n=75) from patients intended to undergo prosthetic joint replacements. Susceptibility to mupirocin (used for eradication of nasal carriership of Staphylococcus aureus) was investigated by gradient test, and susceptibility to various other antimicrobial agents was investigated by disc diffusion test. All isolates, except three from PJIs and one from the nares, were fully susceptible to mupirocin. Multi-drug resistance (≥3 antibiotic classes) was found in 154/183 (84.2%) of the PJI isolates but only in 2/75 (2.7%) of the nares isolates, indicating that S. epidermidis causing PJIs do not originate from the nares.

Diagnostic Methods for Prosthetic Joint Infection in Korea

Prosthetic joint infection (PJI) poses a burden on patients and health care resources. PJI diagnosis can be challenging, owing to imperfect definition, alongside inadequate diagnostic techniques. In this review, we describe consensus definitions of PJI, approaches to diagnosis using methods available in Korea, and novel diagnostic methods.

A Chlorhexidine Solution Reduces Aerobic Organism Growth in Operative Splash Basins in a Randomized Controlled Trial

BACKGROUND

Despite recommendations against the use of splash basins, due to the potential of bacterial contamination, our observation has been that they continue to be used in operating theaters. In hopes of decontaminating the splash basin, we sought to determine if the addition of chlorhexidine gluconate (CHG) would eliminate aerobic bacterial growth within the splash basin.

METHODS

After Institutional Review Board approval, we began enrollment in a randomized controlled trial comparing 2 splash basin solutions. Splash basins (n = 111) were randomized to either the standard of care (control) solution of sterile water or the experimental solution containing 0.05% CHG. One 20 mL aliquot was taken from the basin at the end of the surgical case and delivered to an independent laboratory. Samples were plated on tryptic soy agar (medium) and incubated at 30°C-35°C to encourage growth. After 48-72 hours, the agar plates were examined for growth and a standard plate count of aerobic cultures was performed.

RESULTS

The sterile water group was found to have bacterial growth in 9% of samples compared to no growth in the CHG group (P = .045). The organisms included Micrococcus luteus, Staphylococcus hominis, Gram-variable coccobacilli, and unidentifiable Gram-positive rods.

CONCLUSION

Given the safety and efficacy of a concentration of 0.05% CHG in reducing the bacterial contamination in the operative splash basin, it would seem that if the practice of using a splash basin in the operating theater is to be continued, the addition of an antiseptic solution such as that studied here should be considered.

Formulation and Characterization of Ciprofloxacin loaded PLGA Microspheres for Applications in Orthopedic Infections

ABSTRACT: Purpose-Osteomyelitis is a bone infection that appears as a complication after a fracture or orthopedic surgery. Ciprofloxacin is a broad spectrum antibiotic that can be used in local drug delivery systems for the treatment of bone related infections due to its bactericidal activity against both Gram-negative and Gram-positive bacteria. The purpose of the present study was to include ciprofloxacin in poly (lactic-co-glycolic acid) (PLGA) microspheres. Material and methods-Microspheres were prepared by both water/oil/water (w/o/w) solvent evaporation method and solid/oil/water (s/o/w) dispersion solvent evaporation method. The obtained microspheres were characterized by Fourier Transform Infrared Spectroscopy. High performance liquid chromatography method was deployed to determine the encapsulation ratio. Results-The solvent evaporation method chosen for this experiment resulted in microspheres with good entrapment efficiency. Furthermore the microspheres obtained by the s/o/w method displayed better entrapment efficiency. Conclusion-The particles obtained through the s/o/w technique should be further investigated in order to develop a local drug delivery system.

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

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

Presepsin: A potential biomarker of PJI? A comparative analysis with known and new infection biomarkers

There is still no "gold standard" for the diagnosis and prognosis of post-operative periprosthetic joint infection (PJI). Among serum biomarkers, an emerging molecule is presepsin, the soluble fraction of CD14, recently described in other settings as a powerful diagnostic tool to detect sepsis at different degrees of severity. The aim of this study was to investigate the diagnostic and prognostic value of presepsin in PJI. A total of 30 patients with PJI and 30 patients without PJI were enrolled. Presepsin, C-reactive protein (CRP), serum interleukin (IL)-6, triggering receptor expressed on myeloid cells 1 (TREM-1), CCL2, matrix metalloproteinase 9 (MMP-9), CD163, osteopontin (OPN), and toll-like receptor 2 (TLR2) were measured at different times after surgery. Receiver operating characteristic (ROC) curves and area under the curve (AUC) were analyzed for each biomarker. Presepsin showed greater diagnostic value than CRP and IL-6; CD163, TREM-1, and MMP-9 had very low diagnostic potential. Presepsin, OPN, CCL2, suPAR, and TLR2 all decreased significantly with increasing time of recovery after surgery in PJI patients. Presepsin can be considered a useful tool for the diagnosis and clinical monitoring of PJI and can be backed by a panel of new inflammatory markers involved in monocyte-/macrophage-mediated inflammatory responses, such as OPN, CCL2, TLR2, and suPAR.

Novel Diagnostics in Revision Arthroplasty: Implant Sonication and Multiplex Polymerase Chain Reaction

In orthopedic patients, foreign body-associated infections, especially periprosthetic joint infections (PJIs), are a devastating complication of arthroplasty. Infection requires complex treatment, may result in long hospitalization and causes considerable costs. Multiple surgical revisions can be necessary in these patients, with a loss in function as well as in quality of life.

The routine preoperative diagnostics include blood examination for C-reactive protein (CRP) and other biomarkers, as well as joint aspirate analysis for cell count, differentiation, and culture. Intraoperative specimens for histology and microbiology are also standard procedure. The microbiological examination of removed implants with sonication, in combination with the implementation of molecular biology techniques in microbiology, represent two novel techniques currently employed to enhance the differential diagnostics of PJI.

We present here the step-wise procedure of analyzing joint aspirate and sonication fluid, using a cartridge-based multiplex polymerase chain reaction (PCR) system. Results were matched against conventional cultures and consensus criteria for PJI. Conventional microbiological cultures from tissue biopsies, joint aspirate and sonication fluid showed a sensitivity of 66.7%, 66.7%, and 88.9%, respectively, and a specificity of 82.3%, 54.6%, and 61.5%, respectively. The PCR diagnostic of the sonication fluid and the joint fluid showed a sensitivity of 50.0% and 55.6%, respectively, and both a specificity of 100.0%. Both PCR diagnostics combined had a sensitivity of 66.7% and a specificity of 100.0%. The multiplex PCR therefore presents a rapid diagnostic tool with moderate sensitivity but high specificity in diagnosing PJI.

Osteomyelitis Risk in Patients With Transfemoral Amputations Treated With Osseointegration Prostheses

BACKGROUND

Percutaneous anchoring of femoral amputation prostheses using osseointegrating titanium implants has been in use for more than 25 years. The method offers considerable advantages in daily life compared with conventional socket prostheses, however long-term success might be jeopardized by implant-associated infection, especially osteomyelitis, but the long-term risk of this complication is unknown.

QUESTIONS/PURPOSES

(1) To quantify the risk of osteomyelitis, (2) to characterize the clinical effect of osteomyelitis (including risk of implant extraction and impairments to function), and (3) to determine whether common patient factors (age, sex, body weight, diabetes, and implant component replacements) are associated with osteomyelitis in patients with transfemoral amputations treated with osseointegrated titanium implants.

METHODS

We retrospectively analyzed our first 96 patients receiving femoral implants (102 implants; mean implant time, 95 months) treated at our center between 1990 and 2010 for osteomyelitis. Six patients were lost to followup. The reason for amputation was tumor, trauma, or ischemia in 97 limbs and infection in five. All patients were referred from other orthopaedic centers owing to difficulty with use or to be fitted with socket prostheses. If found ineligible for this implant procedure no other treatment was offered at our center. Osteomyelitis was diagnosed by medical chart review of clinical signs, tissue culture results, and plain radiographic findings. Proportion of daily prosthetic use when osteomyelitis was diagnosed was semiquantitatively graded as 1 to 3. Survivorship free from implant- associated osteomyelitis and extraction attributable to osteomyelitis respectively was calculated using the Kaplan-Meier estimator. Indication for extraction was infection not responsive to conservative treatment with or without minor débridement or loosening of implant.

RESULTS

Implant-associated osteomyelitis was diagnosed in 16 patients corresponding to a 10-year cumulative risk of 20% (95% CI 0.12-0.33). Ten implants were extracted owing to osteomyelitis, with a 10-year cumulative risk of 9% (95% CI 0.04-0.20). Prosthetic use was temporarily impaired in four of the six patients with infection who did not undergo implant extraction. With the numbers available, we did not identify any association between age, BMI, or diabetes with osteomyelitis; however, this study was underpowered on this endpoint.

CONCLUSION

The increased risk of infection with time calls for numerous measures. First, patients should be made aware of the long-term risks, and the surgical team should have a heightened suspicion in patients with method-specific presentation of possible infection. Second, several research questions have been raised. Will the surgical procedure, rehabilitation, and general care standardization since the start of the program result in lower infection rates? Will improved diagnostics and early treatment resolve infection and prevent subsequent extraction? Although not supported in this study, it is important to know if most infections arise as continuous bacterial invasion from the skin and implant interface and if so, how this can be prevented?

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Cutibacterium (formerly Propionibacterium) acnes infections associated with implantable devices

INTRODUCTION

Cutibacterium acnes (C. acnes), a Gram-positive biofilm-forming rod implicated in acne vulgaris, is increasingly recognized for its role in implant-associated infections. The diagnosis of C. acnes implant-associated infections remains challenging. The optimal treatment is a combination of both surgical intervention and antibiotic therapy. Areas covered: In this review, we discuss the different types of implant-associated infections caused by C. acnes. We also highlight the clinical manifestations pertaining to the various sites of infection, and identify several risk factors previously reported in the literature. We then cover the diagnostic laboratory markers, such as IL-6 and AD-1, optimizing C. acnes recovery in culture, and the specific molecular techniques. Finally, we examine the various effective antibiotic regimens and identify some preventive methods against C. acnes infections. Expert commentary: Biomarkers such as IL-6 and AD-1 should be further investigated for the diagnosis of C. acnes implant-associated infections. The use of 16S rRNA gene sequencing and other molecular techniques should be further explored in this setting. Longer incubation periods should be requested whenever C. acnes infection is suspected. If the clinical suspicion is high, sonication of the excised implant should be encouraged. Research should focus on developing effective anti-biofilm agents. Finally, preventive methods such as hair removal prior to surgery should be further explored.

Environment of care: Is it time to reassess microbial contamination of the operating room air as a risk factor for surgical site infection in total joint arthroplasty?

In the modern operating room (OR), traditional surgical mask, frequent air exchanges, and architectural barriers are viewed as effective in reducing airborne microbial populations. Intraoperative sampling of airborne particulates is rarely performed in the OR because of technical difficulties associated with sampling methodologies and a common belief that airborne contamination is infrequently associated with surgical site infections (SSIs). Recent studies suggest that viable airborne particulates are readily disseminated throughout the OR, placing patients at risk for postoperative SSI. In 2017, virtually all surgical disciplines are engaged in the implantation of selective biomedical devices, and these implants have been documented to be at high risk for intraoperative contamination. Approximately 1.2 million arthroplasties are performed annually in the United States, and that number is expected to increase to 3.8 million by the year 2030. The incidence of periprosthetic joint infection is perceived to be low (<2.5%); however, the personal and fiscal morbidity is significant. Although the pharmaceutic and computer industries enforce stringent air quality standards on their manufacturing processes, there is currently no U.S. standard for acceptable air quality within the OR environment. This review documents the contribution of air contamination to the etiology of periprosthetic joint infection, and evidence for selective innovative strategies to reduce the risk of intraoperative microbial aerosols.

Medical comorbidities and perioperative allogeneic red blood cell transfusion are risk factors for surgical site infection after shoulder arthroplasty

BACKGROUND

Multiple perioperative factors have been implicated in infection risk after shoulder arthroplasty. The purpose of this study was to determine surgical site infection (SSI) risk due to medical comorbidities or blood transfusion after primary or revision shoulder arthroplasty.

METHODS

Comprehensive data on medical comorbidities, surgical indication, perioperative transfusion, and SSI were obtained for 707 patients who underwent primary or revision hemiarthroplasty or total shoulder arthroplasty in a single hospital system. Multivariate Poisson regression was used to determine the independent association between allogeneic red blood cell transfusion, medical comorbidities, and SSI after controlling for procedure.

RESULTS

The SSI rate was 1.9% for primary hemiarthroplasties and 1.3% for primary total shoulder arthroplasties. Among patients without prior shoulder infection, revision arthroplasty or prior open reduction and internal fixation had higher SSI risk than primary arthroplasties (incidence risk ratio [IRR], 11.4; 95% confidence interval [CI], 3.84-34.0; P < .001); among primary arthroplasties, SSI risk factors included male gender (IRR, 60.0; CI, 4.39-819; P = .002), rheumatoid arthritis (IRR, 8.63; CI, 1.84-40.4; P = .006), and long-term corticosteroid use (IRR, 37.4; CI, 5.79-242; P < .001). Perioperative allogeneic red blood cell transfusion significantly increased SSI risk and was dose dependent (IRR, 1.68 per unit packed red blood cell; CI, 1.21-2.35; P = .002).

CONCLUSION

Gender, rheumatoid arthritis, and long-term (>1 year) corticosteroid use affect SSI risk after shoulder arthroplasty. Revision surgery, particularly in the setting of prior infection, increased risk of future infection. Finally, allogeneic red blood cell transfusion increases SSI risk after shoulder arthroplasty in a dose-dependent manner.