The challenge of methicillin resistant staphylococcal infection after total hip replacement

High Risk for Persistent Peri-Prosthetic Infection and Amputation in Mega-Prosthesis Reconstruction

A peri-prosthetic joint infection is a feared complication after mega-prosthesis reconstruction of large bone defects. The current study investigates how patients operated with a mega-prosthesis due to sarcoma, metastasis, or trauma, are affected by a deep infection focusing on re-operations, risk for persistent infection, arthrodesis, or subsequent amputation. Time to infection, causative bacterial strains, mode of treatment and length of hospital stay are also reported. A total of 114 patients with 116 prostheses were evaluated, a median of 7.6 years (range 3.8-13.7) after surgery, of which 35 (30%) were re-operated due to a peri-prosthetic infection. Of the infected patients, the prosthesis was still in place in 51%, 37% were amputated, and 9% had an arthrodesis. The infection was persistent in 26% of the infected patients at follow-up. The mean total length of hospital stay was 68 (median 60) days and the mean number of reoperations was 8.9 (median 6.0). The mean length of antibiotic treatment was 340 days (median 183). Coagulase-negative staphylococci and Staphylococcus aureus were the most frequent bacterial agents isolated in deep cultures. No MRSA- or ESBL-producing Enterobacterales were found but vancomycin-resistant Enterococcus faecium was isolated in one patient. In summary, there is a high risk for peri-prosthetic infection in mega-prostheses, resulting in persistent infection or amputation relatively often.

Approaching prosthesis infection environment: Development of an innovative in vitro Staphylococcus aureus biofilm model

The major role and implication of bacterial biofilms in the case of bone and prosthesis infections have been highlighted and often linked to implant colonization. Management strategies of these difficult-to-treat infections consist in surgeries and antibiotic treatment, but the rate of relapse remains high, especially if Staphylococcus aureus, a high-virulent pathogen, is involved. Therapeutic approaches are not adapted to the specific features of biofilm in bone context whereas infectious environment is known to importantly influence biofilm structure. In the present study, we aim to characterize S. aureus SH1000 (methicillin-sensitive strain, MSSA) and USA300 (methicillin-resistant strain, MRSA) biofilm on different surfaces mimicking the periprosthetic environment. As expected, protein adsorption on titanium enhanced the number of adherent bacteria for both strains. On bone explant, USA300 adhered more than SH1000. The simultaneous presence of two different surfaces was also found to change the bacterial behaviour. Thus, proteins adsorption on titanium and bone samples (from bank or directly recovered after an arthroplasty) were found to be key parameters that influence S. aureus biofilm formation: adhesion, matrix production and biofilm-related gene regulation. These results highlighted the need for new biofilm models, more relevant with the infectious environment by using adapted culture medium and presence of surfaces that are representative of in situ conditions to better evaluate therapeutic strategies against biofilm.

Recent Advances in Multifunctional Hydrogels for the Treatment of Osteomyelitis

Osteomyelitis (OM), a devastating disease caused by microbial infection of bones, remains a major challenge for orthopedic surgeons. Conventional approaches for prevention and treatment of OM are unsatisfactory. Various alternative strategies have been proposed, among which, hydrogel-based strategies have demonstrated potential due to their unique properties, including loadable, implantable, injectable, printable, degradable, and responsive to stimuli. Several protocols, including different hydrogel designs, selection of antimicrobial agent, co-administration of bone morphogenetic protein 2 (BMP 2), and nanoparticles, have been shown to improve the biological properties, including antimicrobial effects, osteo-induction, and controlled drug delivery. In this review, we describe the current and future directions for designing hydrogels and their applications to improve the biological response to OM in vivo.

The Risk Factor and Outcome of Metachronous Periprosthetic Joint Infections: A Retrospective Analysis With a Minimum Ten-Year Follow-Up

BACKGROUND

Patients with multiple prosthetic joints are at risk of developing periprosthetic joint infections (PJIs). We aimed to determine whether PJI development at one site may lead to infection at another prosthetic joint site and assess the risk factors leading to this subsequent infection.

METHODS

We reviewed all cases (294 patients with first-time PJI [159 hips, 135 knees]) with PJI treated at our institute between January 1994 and December 2020. The average follow-up period was 11.2 years (range 10.1-23.2). Patients were included if they had at least one other prosthetic joint at the time of developing a single PJI (96 patients). Patients with synchronous PJI were excluded from the study. The incidence of metachronous PJI was assessed, and the risk factors were determined by comparing different characteristics between patients without metachronous PJI.

RESULTS

Of the 96 patients, 19.79% developed metachronous PJI. The identified causative pathogen was the same in 63.16% of the patients. The time to developing a second PJI was 789.84 days (range 10-3386). The identified risk factors were PJI with systemic inflammatory response syndrome, ≥3 stages of resection arthroplasty, and PJI caused by methicillin-resistant Staphylococcus aureus.

CONCLUSION

PJI may predispose patients to subsequent PJI in another prosthesis with identified risks. Most causative organisms of metachronous PJI were the same species as those of the first PJI. We believe that bacteremia may be involved in pathogenesis, but further research is required.

A Hyaluronic Acid Hydrogel Loaded with Gentamicin and Vancomycin Successfully Eradicates Chronic Methicillin-Resistant Staphylococcus aureus Orthopedic Infection in a Sheep Model

Implantable orthopedic devices have had an enormously positive impact on human health; however, despite best practice, patients are prone to developing orthopedic device-related infections (ODRI) that have high treatment failure rates. One barrier to the development of improved treatment options is the lack of an animal model that may serve as a robust preclinical assessment of efficacy. We present a clinically relevant large animal model of chronic methicillin-resistant Staphylococcus aureus (MRSA) ODRI that persists despite current clinical practice in medical and surgical treatment at rates equivalent to clinical observations. Furthermore, we showed that an injectable, thermoresponsive, hyaluronic acid-based hydrogel loaded with gentamicin and vancomycin outperforms current clinical practice treatment in this model, eliminating bacteria from all animals. These results confirm that local antibiotic delivery with an injectable hydrogel can dramatically increase treatment success rates beyond current clinical practice, with efficacy proven in a robust animal model.

Single-stage revision of MRSA orthopedic device-related infection in sheep with an antibiotic-loaded hydrogel

Local antimicrobial therapy is an integral aspect of treating orthopedic device-related infection (ODRI), which is conventionally administered via polymethyl-methacrylate (PMMA) bone cement. PMMA, however, is limited by a suboptimal antibiotic release profile and a lack of biodegradability. In this study, we compare the efficacy of PMMA versus an antibiotic-loaded hydrogel in a single-stage revision for chronic methicillin-resistant Staphylococcus aureus (MRSA) ODRI in sheep. Antibiofilm activity of the antibiotic combination (gentamicin and vancomycin) was determined in vitro. Swiss alpine sheep underwent a single-stage revision of a tibial intramedullary nail with MRSA infection. Local gentamicin and vancomycin therapy was delivered via hydrogel or PMMA (n = 5 per group), in conjunction with systemic antibiotic therapy. In vivo observations included: local antibiotic tissue concentration, renal and liver function tests, and quantitative microbiology on tissues and hardware post-mortem. There was a nonsignificant reduction in biofilm with an increasing antibiotic concentration in vitro (p = 0.12), confirming the antibiotic tolerance of the MRSA biofilm. In the in vivo study, four out of five sheep from each treatment group were culture-negative. Antibiotic delivery via hydrogel resulted in 10-100 times greater local concentrations for the first 2-3 days compared with PMMA and were comparable thereafter. Systemic concentrations of gentamicin were minimal or undetectable in both groups, while renal and liver function tests were within normal limits. This study shows that a single-stage revision with hydrogel or PMMA is equally effective, although the hydrogel offers certain practical benefits over PMMA, which make it an attractive proposition for clinical use.

Total hip arthroplasty following illicit drug abuse

BACKGROUND

The role of illicit drug abuse in total joint arthroplasty is largely unknown and is likely underestimated. Patients with drug addictions often suffer from septic osteoarthritis or a necrosis of the femoral head. Purpose of the study was to evaluate the operative management and clinical outcome of total hip replacement in patients with a history of intravenous drug abuse.

METHODS

This retrospective study included 15 patients with a history of intravenous drug abuse who underwent total hip arthroplasty. A total of 6 females and 9 males with an average age of 34.3 years were identified. Ten patients presented an acute bacterial coxitis (Coxitis-group) and five an aseptic osteonecrosis of the femoral head (Osteonecrosis-group).

RESULTS

Ten patients with a bacterial coxitis underwent a two-staged total hip arthroplasty (THA), with temporary insertion of a drug-eluting spacer. Five patients with a necrosis of the femoral head were primarily treated with THA. All patients developed multiple re-infections after insertion of a drug-eluting spacer or THA. Only two patients finally achieved a THA without infection in the period of 3.9 years follow-up. The other 13 patients underwent a Girdlestone arthroplasty (7 patients) or total joint replacement with a chronic fistula (6 patients).

CONCLUSION

THA in patients with illicit drug abuse shows a low success rate. Following septic osteoarthritis or osteonecrosis in drug-addicted patients, we recommend a two-stage procedure with temporary insertion of a drug-eluting spacer. THA might follow only under strict premises.

Evaluation of Oritavancin Combinations with Rifampin, Gentamicin, or Linezolid against Prosthetic Joint Infection-Associated Methicillin-Resistant Staphylococcus aureus Biofilms by Time-Kill Assays

The antibiofilm activity of oritavancin in combination with rifampin, gentamicin, or linezolid was evaluated against 10 prosthetic joint infection (PJI)-related methicillin-resistant Staphylococcus aureus (MRSA) isolates by time-kill assays. Oritavancin combined with rifampin demonstrated statistically significant bacterial reductions compared with those of either antimicrobial alone for all 10 isolates (P ≤ 0.001), with synergy being observed for 80% of the isolates. Oritavancin and rifampin combination therapy may be an option for treating MRSA PJI.

The Cost-Effectiveness of Preoperative Staphylococcus aureus Screening and Decolonization in Total Joint Arthroplasty

BACKGROUND

This article presents a break-even analysis for preoperative Staphylococcus aureus colonization screening and decolonization protocols in total hip arthroplasty (THA) and total knee arthroplasty (TKA).

METHODS

Protocol costs, baseline infection rates after arthroplasty, and average revision costs were obtained from institutional records and the literature. The break-even analysis determined the absolute risk reduction (ARR) in infection rate required for cost-effectiveness.

RESULTS

S aureus nasal screening ($144.07) was cost effective when initial infection rates of TKA (1.10%) and THA (1.63%) had an ARR of 0.56% and 0.45%, respectively. The most inexpensive decolonization treatment ($5.09) was cost effective with an ARR of 0.02% for both TKA and THA. The most expensive decolonization option ($37.67) was cost effective with ARRs of 0.15% (TKA) and 0.12% (THA).

CONCLUSION

Preoperative S aureus decolonization can be highly cost effective, whereas colonization screening requires excessively high reductions in infection rate.

Outcome of hip and knee periprosthetic joint infections caused by pathogens resistant to biofilm-active antibiotics: results from a prospective cohort study

BACKGROUND

Periprosthetic joint infections (PJI) caused by pathogens, for which no biofilm-active antibiotics are available, are often referred to as difficult-to-treat (DTT). However, it is unclear whether the outcome of DTT PJI is worse than those of non-DTT PJI. We evaluated the outcome of DTT and non-DTT PJI in a prospective cohort treated with a two-stage exchange according to a standardized algorithm.

METHODS

Patients with hip and knee PJI from 2013 to 2015 were prospectively included and followed up for ≥ 2 years. DTT PJI was defined as growth of microorganism(s) resistant to all available biofilm-active antibiotics. The Kaplan-Meier survival analysis was used to compare the probability of infection-free survival between DTT and non-DTT PJI and the 95% confidence interval (95% CI) was calculated.

RESULTS

Among 163 PJI, 30 (18.4%) were classified as DTT and 133 (81.6%) as non-DTT. At a mean follow-up of 33 months (range 24-48 months), the overall treatment success was 82.8%. The infection-free survival rate at 2 years was 80% (95% CI 61-90%) for DTT PJI and 84% (95% CI 76-89%) for non-DTT PJI (p = 0.61). The following mean values were longer in DTT PJI than in non-DTT PJI: hospital stay (45 vs. 28 days; p < 0.001), prosthesis-free interval (89 vs. 58 days; p < 0.001) and duration of antimicrobial treatment (151 vs. 117 days; p = 0.003).

CONCLUSIONS

The outcome of DTT and non-DTT PJI was similar (80-84%), however, at the cost of longer hospital stay, longer prosthesis-free interval and longer antimicrobial treatment. It remains unclear whether patients undergoing two-stage exchange with a long interval need biofilm-active antibiotics. Further studies need to evaluate the outcome in patients treated with biofilm-active antibiotics undergoing short vs. long interval.

Can a Silver-Coated Arthrodesis Implant Provide a Viable Alternative to Above Knee Amputation in the Unsalvageable, Infected Total Knee Arthroplasty?

BACKGROUND

In the unsalvageable, infected total knee arthroplasty, knee arthrodesis is one treatment option with lower reported reinfection rates compared with repeated 2-stage revision and improved function compared with amputation. One possible method for reducing incidence of recurrent infection treated by arthrodesis is the use of a silver-coated implant. We report our experience of silver-coated arthrodesis nails used for managing infected revision arthroplasty. We primarily assess the rate of reinfection and rate of amputation and report functional outcome measures.

METHODS

Retrospective analysis of all patients undergoing knee arthrodesis with a silver-coated arthrodesis nail between 2008 and 2014. Patient-reported data were recorded prearthrodesis and postarthrodesis (Oxford Knee Score and Short Form-36) as well as evidence of recurrent of infection, subsequent surgery, and the necessity for amputation.

RESULTS

Eight patients underwent arthrodesis using the silver-coated arthrodesis nail. Mean duration of follow-up was 16 months (5-35 months). At the point of follow-up, there were no amputations, deaths, or implant revisions. One case of recurrent infection was successfully treated with washout and debridement. The mean prearthrodesis and postarthrodesis Oxford Knee Score difference was +8.9 points (P = .086) with significantly improved pain (P = .019), night pain (P = .021), and ease of standing (P = .003).

CONCLUSION

Arthrodesis of the knee using a silver-coated intramedullary device is successful in eradicating infection and allowing limb conservation. Where infection does recur, this can be successfully treated with implant retention. The use of a silver-coated arthrodesis nail should be considered as an alternative to amputation for patients with a multiply revised and infected total knee arthroplasty.

Methicillin-resistant Staphylococcal periprosthetic joint infections can be effectively controlled by systemic and local daptomycin

Background

Methicillin-resistant Staphylococcus remains a serious problem in the treatment of periprosthetic joint infection (PJI). Higher failure rates were reported when vancomycin was used in 2-stage exchange arthroplasty. Therefore a better therapeutic drug is needed to treat PJI caused by methicillin-resistant organisms. The purpose of the study was to evaluate the safety and efficacy of daptomycin when administered in bone cement combined with systemic use for methicillin-resistant Staphylococci PJI.

Methods

We conducted a retrospective study from January 2010 to December 2012. Twenty-two patients (10 knees and 12 hips) with PJI caused by methicillin-resistant Staphylococcus species underwent 2-stage revision arthroplasty. In the first stage, 10 % daptomycin (weight daptomycin per weight bone cement) was incorporated into polymethylmethacrylate bone cement, and systemic daptomycin (6 mg/kg) was administered postoperatively for 14 days. In the second stage, 2.5 % w/w daptomycin was used in the bone cement. The minimum follow-up was 2 years or until recurrence of infection.

Results

The infecting organisms included methicillin-resistant Staphylococcus aureus in 10 patients, methicillin-resistant Staphylococcus epidermidis in 8 patients and methicillin-resistant coagulase-negative Staphylococci in 4 patients. The mean follow-up duration was 33.7 months (range, 24–51 months). The treatment success rate was 100 %. Only one patient developed asymptomatic transient elevation of the creatine phosphokinase level. No patient experienced any adverse effects related to daptomycin such as myositis, rhabdomyolysis, peripheral neuropathy, derangement of liver function, or eosinophilic pneumonia.

Conclusions

In this series, no serious adverse events occurred. Our protocol, using daptomycin-impregnated cement combined with short duration of systemic daptomycin, appears to be an effective and safe treatment for methicillin-resistant Staphylococcus PJI.

Iodine-Supported Hip Implants: Short Term Clinical Results

We developed a new povidone iodine coating technology for titanium hip implants and performed a clinical trial to assess its usefulness in suppressing postoperative infection. Results indicate that iodine-supported titanium has favorable antibacterial activity, biocompatibility, and no cytotoxicity. Thirty joints in 28 patients were treated using iodine-supported implants. Fourteen joints were revision total hip arthroplasty (THA) after periprosthetic infection, 13 were primary THA for immunosuppressive conditions or pyogenic arthritis, and 3 were conversions from hemiarthroplasty to THA for immunosuppressive conditions. Two examinations were conducted sequentially until final follow-up: white blood cell (WBC) and C-reactive protein (CRP) were measured pre- and postoperatively and thyroid hormone levels in the blood were examined. The mean follow-up period was 33 months (14-78). There were no signs of infection in any patient at the last follow-up. WBC and CRP levels returned to normal within several weeks. No abnormalities of thyroid gland function were detected. Loosening of the implants did not occur in any patient. Excellent bone ingrowth and ongrowth were found around prostheses. No cytotoxicity or adverse effects were detected. These results suggest that iodine-supported THA implants can be highly effective in preventing and treating postoperative infections.

Interleukin-10 production by myeloid-derived suppressor cells contributes to bacterial persistence during Staphylococcus aureus orthopedic biofilm infection

Staphylococcus aureus is known to establish biofilms on medical devices. We recently demonstrated that Ly6G(high)Ly6C(+) myeloid-derived suppressor cells are critical for allowing S. aureus biofilms to subvert immune-mediated clearance; however, the mechanisms whereby myeloid-derived suppressor cells promote biofilm persistence remain unknown. Interleukin-10 expression was significantly increased in a mouse model of S. aureus orthopedic implant biofilm infection with kinetics that mirrored myeloid-derived suppressor cell recruitment. Because myeloid-derived suppressor cells produce interleukin-10, we explored whether it was involved in orchestrating the nonproductive immune response that facilitates biofilm formation. Analysis of interleukin-10-green fluorescent protein reporter mice revealed that Ly6G(high)Ly6C(+) myeloid-derived suppressor cells were the main source of interleukin-10 during the first 2 wk of biofilm infection, whereas monocytes had negligible interleukin-10 expression until day 14. Myeloid-derived suppressor cell influx into implant-associated tissues was significantly reduced in interleukin-10 knockout mice at day 14 postinfection, concomitant with increased monocyte and macrophage infiltrates that displayed enhanced proinflammatory gene expression. Reduced myeloid-derived suppressor cell recruitment facilitated bacterial clearance, as revealed by significant decreases in S. aureus burdens in the knee joint, surrounding soft tissue, and femur of interleukin-10 knockout mice. Adoptive transfer of interleukin-10 wild-type myeloid-derived suppressor cells into S. aureus-infected interleukin-10 knockout mice restored the local biofilm-permissive environment, as evidenced by increased bacterial burdens and inhibition of monocyte proinflammatory activity. These effects were both interleukin-10-dependent and interleukin-10-independent because myeloid-derived suppressor cell-derived interleukin-10 was required for promoting biofilm growth and anti-inflammatory gene expression in monocytes but was not involved in monocyte recruitment to biofilm-infected tissues. These results demonstrate that interleukin-10 production by myeloid-derived suppressor cells contributes to the persistence of S. aureus orthopedic biofilm infections.

In vitro and in vivo evaluation of vancomycin-loaded PMMA cement in combination with ultrasound and microbubbles-mediated ultrasound

Ultrasound (US) has been used to increase elution of antibiotic from an antibiotic-loaded poly(methyl methacrylate) (PMMA) bone cement (ALBC). We aimed to further investigate whether microbubbles-mediated US (US + MB) facilitate elution of vancomycin (VAN) from cylindrical specimens and enhance the activity of the eluted antibiotic against Staphylococcus aureus (S. aureus) in vitro. The study groups comprised cylindrical bone cement fabricated with VAN (VAN), ALBC using US (VAN + US), and ALBC using MB-mediated US (VAN + US + MB). We also carried out an in vivo study involving the activity of VAN from cylindrical cement implanted in tibiae of New Zealand white rabbits inoculated with S. aureus. We found that (1) in vitro, elution from VAN + US + MB cylinders was significantly higher than from either the VAN or VAN + US specimens; (2) the activity of the eluted VAN from the VAN + US + MB cylinders against planktonic S. aureus was significantly higher than from either the control or VAN or VAN + US specimens; and (3) in the rabbits, the activity of the eluted VAN from the VAN + US + MB cylinders against S. aureus was significantly higher than from either the control or VAN or VAN + US specimens. The present results suggest that VAN-loaded PMMA cement irradiated with MB-mediated US may have a role in controlling prosthetic joint infection.