Increased risk of joint failure in hip prostheses infected with Staphylococcus aureus treated with debridement, antibiotics and implant retention compared to Streptococcus

Piezoelectric ultrasonic debridement as new tool for biofilm removal from orthopedic implants: A study in vitro

Pulse lavage (PL) debridement is the standard treatment used in Debridement, Antibiotics and Implant Retention (DAIR) for bacterial biofilm removal during acute and early postoperative cases of periprosthetic joint infection (PJI). The failure rate of DAIR is still high due to the inadequacy of PL in removing the biofilm. Ultrasound-based techniques are a well-established tool for PJI diagnosis due to their ability to completely eradicate the biofilm from implant surfaces. Hence, this study investigates the efficiency of a piezoelectric ultrasonic scalpel (PUS) in removing bacterial biofilm from different orthopedic implant materials in vitro and compares the results with PL. Biofilms of methicillin-resistant Staphylococcus aureus strains were grown on titanium alloy (Ti6Al4V ELI), stainless steel (AISI 316L), and ultrahigh molecular weight polyethylene (UHMWPE) disks for 24 h. The disks of each material were divided into three groups: (i) a control group (no lavage/debridement), (ii) a group treated with PL, (iii) a group treated with PUS. The disks were then sonicated for viable cell count to measure the residual biofilm content. Compared to the initial cell count (105  CFU/mL for each material), PL showed a two-log reduction of CFU/mL (p < 0.001 for each material), while for PUS a four-log reduction was found (p < 0.001 for each material). The comparison between the two lavage/debridement displayed a two-log reduction of CFU/mL (p < 0.001 for each material) of PUS compared with PL. Its increased efficiency compared with PL promotes the use of PUS in removing bacterial biofilm from orthopedic implants, suggesting its implementation to improve the success rate of DAIR.

A recurrent prosthetic joint infection caused by Erysipelothrix rhusiopathiae: case report and literature review

Prosthetic knee joint infection caused by Erysipelothrix rhusiopathiae is uncommon and only one case of recurrent infection has previously been described. Here, we describe the case of a 77-year-old male patient who was admitted to the teaching hospital of Rennes (France) with bilateral and nocturnal gonalgia evolving for 1 month. He had bilateral knee prosthesis 10 years ago, and a history of large B-cell lymphoma in remission. A diagnosis of infective endocarditis, with prosthetic knee infection, was made, with positive cultures of synovial fluids and blood; colonies of E. rhusiopathiae were identified by MALDI-TOF MS. Initial treatment involved debridement, implant retention surgery and intravenous amoxicillin (12 g day^-1) for 6 weeks with gentamicin 3 mg kg^-1 day^-1 added for the first 4 days. One year later, a second episode of E. rhusiopathiae infection occurred, suggesting a recurrence or reinfection due to the same bacterial species. The patient was finally cured after a two-stage exchange with a cemented articulated spacer and a 3 month course of amoxicillin (12 g day^-1, iv). Different characteristics of E. rhusiopathiae infection were discussed, with a review of all cases of prosthetic joint infections caused by Erysipelothrix species. This case highlights the need for a long-term survey of patients, and a good knowledge of their environment to avoid any risk of reinfection.

Streptococcal and Staphylococcus aureus prosthetic joint infections: are they really different?

Background

Staphylococci and streptococci are the most frequent pathogens isolated from prosthetic joint infections (PJIs). The aim of this study was to analyze the outcome of streptococcal and methicillin-susceptible Staphylococcus aureus (MSSA) PJIs.

Methods

All monomicrobial streptococcal and MSSA PJIs managed in a French Referral Center (2010–2017) were sampled from the prospective PJIs cohort study. The primary outcome of interest was the cumulative reinfection-free survival at a 2-year follow-up.

Results

Two hundred and nine patients with 91 streptococcal and 132 staphylococcal infections were analyzed. Patients with streptococcal PJI were older, and infection was more frequently hematogenous. Reinfection-free survival rates at 2-years after all treatment strategies were higher for patients with streptococcal PJI (91% vs 81%; P = .012), but differed according to the strategy. After exchange arthroplasty, no outcome differences were observed (89% vs 93%; P = .878); after debridement, antibiotics and implant retention (DAIR), the reinfection-free survival rate was higher for patients with streptococcal PJI (87% vs 60%; P = .062). For patients managed with prolonged suppressive antibiotic therapy (SAT) alone, those with streptococcal PJIs had a 100% infection-free survival (100% vs 31%; P < .0001).

Conclusions

Reinfection-free survival after DAIR and SAT was better for patients with streptococcal than those with MSSA PJIs. No difference was observed after prosthesis exchange.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07532-x.

Comparison of the success rate after debridement, antibiotics and implant retention (DAIR) for periprosthetic joint infection among patients with or without a sinus tract

BACKGROUND

The relevance between the presence of a sinus tract and the failure risk after debridement, antibiotics and implant retention (DAIR) for periprosthetic joint infection (PJI) after hip or knee arthroplasty is still unclear. This study aimed to compare the success rate of DAIR between patients with or without a sinus tract and to explore the possible risk factors for failure after DAIR in patients with a sinus tract.

METHODS

Consecutive DAIR cases for PJI after hip or knee arthroplasty between January 2009 and June 2019 with a minimum 1-year follow-up in two tertiary joint arthroplasty centers were included. Patients were classified into the sinus tract group and the non-sinus tract group according to the presence of a sinus tract. The success rate after DAIR were compared using Kaplan-Meier survival analysis. Potential risk factors for failure in the sinus group were also explored.

RESULTS

One hundred seven patients were included. At a median 4.4 years of follow-up, 19 of 52 (36.5%) cases failed in the sinus tract group, while 15 of 55 (27.3%) cases failed in the non-sinus tract group. The 1-year and 5-year cumulative success rates were 71.2% (95% confidence interval (CI): 59.8-84.6%) and 56.8% (95% CI: 42.6-75.7%) in the sinus tract group, respectively, which were similar to the counterparts in the non-sinus tract group (P = 0.214). Among patients with a sinus tract, DAIR with the exchange of modular components showed a higher success rate (75.8% versus 47.4%, P = 0.038).

CONCLUSIONS

The presence of a sinus tract does not affect the success rate of DAIR. Modular component exchange in DAIR was proposed for patients with a sinus tract for an improved infection control rate.

Direct-Contact Low-Frequency Ultrasound and Pulse Lavage Eradicates Biofilms on Implant Materials In Vitro

Pulse lavage (PL) debridement and ultrasound are both known to be the treatment of biofilm-related periprosthetic joint infection (PJI). However, the efficacy of these in combination is unknown in eradicating biofilm from the orthopaedic metal implant surface. This study was conducted to understand the efficacy of PL and ultrasound in combination in eradicating bacterial biofilms on titanium alloy in vitro. Biofilms of Staphylococcus aureus strains were grown on titanium alloy coupons for 24 h. Then, the coupons were taken to each treatment group: (i) debrided with PL, (ii) exposed to ultrasound, or (iii) exposed to both. An untreated biofilm was set as a control group. Viable plate count and confocal microscopy using live/dead staining was used to measure the amount of biofilm. Viable plate count showed an approximate two-log reduction in CFU/cm² in PL alone, from an initial cell count on the mental surface of approximately 10⁹ CFU/cm². The ultrasound caused an approximate seven-log reduction, and the combination group eradicated viable biofilm bacteria completely. Confocal imaging corroborated the CFU data. Our results indicate that PL and ultrasound both are remarkably in eradicating biofilm, and the combination of PL and ultrasound is more effective than alone in reducing biofilm.

The James A. Rand Young Investigator's Award: Are Intraoperative Cultures Necessary If the Aspiration Culture Is Positive? A Concordance Study in Periprosthetic Joint Infection

BACKGROUND

The concordance between preoperative synovial fluid culture and multiple intraoperative tissue cultures for identifying pathogenic microorganisms in periprosthetic joint infection (PJI) remains unknown. Our aim is to determine the diagnostic performance of synovial fluid culture for early organism identification.

METHODS

A total of 363 patients who met Musculoskeletal Infection Society criteria for PJI following primary total joint arthroplasty were identified from a retrospective joint infection database. Inclusion criteria required a positive preoperative intra-articular synovial fluid sample within 90 days of intraoperative tissue culture(s) at revision surgery. Concordance was defined as matching organism(s) in aspirate and intraoperative specimens.

RESULTS

Concordance was identified in 279 (76.8%) patients with similar rates among total hip arthroplasties (77.2%) and total knee arthroplasties (76.4%, P = .86). Culture discordance occurred in 84 (23.1%) patients; 37 (10.2%) had no intraoperative culture growth and 33 (90.1%) were polymicrobial. Monomicrobial Staphylococcal PJI cases had high sensitivity (0.96, 95% confidence interval [CI] 0.92-0.98) and specificity (0.85, 95% CI 0.80-0.90). Polymicrobial infections had the lowest sensitivity (0.06, 95% CI 0.01-0.19).

CONCLUSION

Aspiration culture has favorable sensitivity and specificity when compared to tissue culture for identifying the majority of PJI organisms. Clinicians can guide surgical treatment and postoperative antibiotics based on monomicrobial aspiration results, but they should strongly consider collecting multiple tissue cultures to maximize the chance of identifying an underlying polymicrobial PJI.

LEVEL OF EVIDENCE

Level III.

Distinct vasculotropic versus osteotropic features of S. agalactiae versus S. aureus implant-associated bone infection in mice

Osteomyelitis is a devastating complication of orthopaedic surgery and commonly caused by Staphylococcus aureus (S. aureus) and Group B Streptococcus (GBS, S. agalactiae). Clinically, S. aureus osteomyelitis is associated with local inflammation, abscesses, aggressive osteolysis, and septic implant loosening. In contrast, S. agalactiae orthopaedic infections generally involve soft tissue, with acute life-threatening vascular spread. While preclinical models that recapitulate the clinical features of S. aureus bone infection have proven useful for research, no animal models of S. agalactiae osteomyelitis exist. Here, we compared the pathology caused by these bacteria in an established murine model of implant-associated osteomyelitis. In vitro scanning electron microscopy and CFU quantification confirmed similar implant inocula for both pathogens (~10⁵ CFU/pin). Assessment of mice at 14 days post-infection demonstrated increased S. aureus virulence, as S. agalactiae infected mice had significantly greater body weight, and fewer CFU on the implant and in bone and adjacent soft tissue (p < 0.05). X-ray, µCT, and histologic analyses showed that S. agalactiae induced significantly less osteolysis and implant loosening, and fewer large TRAP⁺ osteoclasts than S. aureus without inducing intraosseous abscess formation. Most notably, transmission electron microscopy revealed that although both bacteria are capable of digesting cortical bone, S. agalactiae have a predilection for colonizing blood vessels embedded within cortical bone while S. aureus primarily colonizes the osteocyte lacuno-canalicular network. This study establishes the first quantitative animal model of S. agalactiae osteomyelitis, and demonstrates a vasculotropic mode of S. agalactiae infection, in contrast to the osteotropic behavior of S. aureus osteomyelitis.

Factors affecting outcome in the treatment of streptococcal periprosthetic joint infections: results from a single-centre retrospective cohort study

PURPOSE

To report and analyse factors affecting the outcome of streptococcal periprosthetic joint infections (PJIs).

METHODS

A retrospective analysis of consecutive streptococcal PJIs was performed. Musculoskeletal Infection Society 2013 criteria were used. Outcome was compared with a prospective PJI cohort from the same institution.

RESULTS

The most common isolated streptococcal species was Streptococcus dysgalactiae (9/22, 41%) among 22 patients included. Surgical treatment consisted of DAIR (debridement, antibiotics, irrigation and retention) in 12 (55%), one-stage revision arthroplasty in one (4%), two-stage revision arthroplasty in eight (37%) and implant removal in one (4%) patient. An infection free-outcome was achieved in 15 cases (68%), whilst seven (32%) patients failed initial revision and relapsed with the same pathogen, from which six were treated with DAIR and one with one-stage revision arthroplasty. No failures were observed in patients who received a two-stage revision. Failure rates did not differ in the cases treated with rifampin (1/5) from those without 6/17 (p = 0.55). There was no correlation between the length of antibiotic treatment and relapse (p = 0.723). In all failures, a persistent distant infection focus was identified at the time of relapse. Compared with our prospective PJI cohort, relapse rates were significantly higher 32% vs 12% (p < 0.05).

CONCLUSION

No correlation with the use of rifampin or length of antibiotic treatment was found. No failures were observed in patients who received a two-stage revision, which may be the surgical treatment of choice. A distant persisting infection focus could be the reason for PJI relapse with recurrent hematogenous seeding in the joint.

Calculated parenteral initial treatment of bacterial infections: Bone and joint infections

This is the 10^th chapter of the guideline “Calculated initial parenteral treatment of bacterial infections in adults – update 2018” in the 2^nd updated version. The German guideline by the Paul-Ehrlich-Gesellschaft für Chemotherapie e.V. (PEG) has been translated to address an international audience.

This chapter deals with bacterial Infections of bones, joints and prosthetic joints. One of the most pressing points is that after an initial empirical therapy a targeted antimicrobial which penetrates well to the point of infection and is tolerated well over the usually long duration of the therapy is chosen.

Evaluation One Year after DAIR Treatment in 91 Suspected Early Prosthetic Joint Infections in Primary Knee and Hip Arthroplasty

INTRODUCTION

Early recognition and appropriate initial treatment with debridement, antibiotics and implant retention (DAIR) if a suspicion of an early prosthetic joint infection (PJI) is present can eradicate infection on first attempt and prevent implant failure. We evaluated the outcome after 1 year of patients treated with DAIR after primary total knee arthroplasty (TKA) or total hip arthroplasty (THA). Furthermore, we determined preoperative, microbiology, and treatment factors related to failure after DAIR.

METHODS

A retrospective cohort study was assembled with 91 patients undergoing DAIR with a high suspicion of an early PJI. Records were reviewed for demographics, preoperative laboratory results, microbiological data, given treatment and postoperative follow-up. The primary outcome was infection-free implant survival at 1 year. Repeated DAIR was not considered as treatment failure.

RESULTS

The rate of infection-free implant survival following DAIR in a suspected early PJI was 85% (95% confidence intervals (CI) 78-91). Cultures remained negative in 20 patients, with no occurrence of infection during follow-up. A higher failure rate was seen in early PJI caused by Enterococcus faecalis (p=0.04). Multivariate analysis showed a statistically significant association between treatment failure and high C-reactive protein level (CRP >100) (odds ratio 10.0, 95% CI [1.5-70]) and multiple DAIR procedures (≥2) (odds ratio 5.0, 95%CI [1.1-23]).

CONCLUSION

If an early PJI is suspected DAIR is the appointed treatment with up to 2 debridement procedures. Since culture-negative DAIRs were not related to any complications during follow-up, overtreatment of suspected PJI seems to do no significant harm with respect to implant failure.

Debridement, Antibiotics and Implant Retention for Early Periprosthetic Infections of the Hip: Outcomes and Influencing Factors

Purpose

Debridement, antibiotics and implant retention (DAIR) is commonly performed and widely accepted for the treatment of acute infections following hip arthroplasty. The aims of this study were to: i) determine the DAIR success rate in treating acute postoperative and hematogenous periprosthetic infections of the hip at a tertiary hospital, ii) identify possible outcome predictors, and iii) analyze clinical and radiological outcomes.

Materials and Methods

We retrospectively reviewed cases of acute postoperative (≤3 months from index procedure) and hematogenous periprosthetic infections following total hip arthroplasty treated with DAIR at our hospital between 2004 and 2015. Overall, 26 hips (25 patients) were included in the study, with a mean age of 72.5 years (standard deviation [SD], 9.4). The mean follow-up was 48.5 months (SD, 43.7). Several variables (e.g., patient characteristics, infection type, surgery parameters) were examined to evaluate their influence on outcomes; functional and radiographic outcomes were assessed.

Results

The overall success rate of DAIR was 26.9%. The male sex was associated with treatment failure (P=0.005) and debridement performed by a surgeon in hip unit with success (P=0.028). DAIR failure increased in patients with chronic pulmonary disease (P=0.059) and steroid therapy (P=0.062). Symptom duration of <11 days until DAIR yielded a better infection eradication rate (P=0.068). The mean postoperative Harris Hip Score was 74.2 (SD, 16.6).

Conclusion

DAIR, despite being used frequently, had a high failure rate in our series. Outcomes improved if an experienced hip arthroplasty surgeon performed the surgery. Patient comorbidities and symptom duration should be considered for decision-making.

The prognosis of streptococcal prosthetic bone and joint infections depends on surgical management-A multicenter retrospective study

BACKGROUND

The optimal treatment of streptococcal prosthetic joint infections (PJIs) is unclear.

METHODS

A cohort of streptococcal PJIs was reviewed retrospectively in seven reference centers for the management of complex bone and joint infections, covering the period January 1, 2010 to December 31, 2012.

RESULTS

Seventy patients with monomicrobial infections were included: 47 had infections of total hip arthroplasty and 23 had infections of total knee arthroplasty. The median age was 77 years (interquartile range (IQR) 69-83 years), the median Charlson comorbidity score was 4 (IQR 3-6), and 15.6% (n=11) had diabetes. The most commonly identified streptococcal species were Streptococcus agalactiae and Streptococcus dysgalactiae (38.6% (n=27) and 17.1% (n=12), respectively). Debridement, antibiotics and implant retention (DAIR) was performed after a median time of 7 days (IQR 3-8 days), with polyethylene exchange (PE) in 21% of cases. After a minimum follow-up of 2 years, 27% of patients had relapsed, corresponding to 51.4% of DAIR treatment cases and 0% of one-stage (n=15) or two-stage (n=17) exchange strategy cases. Rifampicin or levofloxacin in combination therapy was not associated with a better outcome (adjusted p= 0.99). S. agalactiae species and DAIR treatment were associated with a higher risk of failure. On multivariate analysis, only DAIR treatment and S. agalactiae were independent factors of relapse. Compared to DAIR without PE, DAIR with PE was only associated with a trend towards a benefit (odds ratio 0.33, 95% confidence interval 0.06-1.96; adjusted p= 0.44).

CONCLUSIONS

Streptococcal PJIs managed with DAIR have a poor prognosis and S. agalactiae seems to be an independent factor of treatment failure.

Pilot study: Internally cooled orthopedic drills - standard sterilization is not enough?

Bone drilling causes focal temperature rise due to metal-to-bone contact, which may result in thermal osteonecrosis. Newly constructed internally cooled medical drill of an open type decreases temperature rise at a point of metal-to-bone contact although standard sterilization of such a drill could be inadequate due to bacteria retention within the drill lumen. The aim of this pilot study was to examine the effectiveness of sterilization and to propose sterilization recommendations for internally cooled open type bone drills. Unused internally cooled medical steel bone drills were tested. Drills were contaminated with Pseudomonas aeruginosa, Bacillus sp., beta-hemolytic Streptococcus sp., Enterobacter sp. and methicillin-resistant Staphylococcus pseudintermedius and then incubated for 24 hours at 37 °C. Afterwards, drills were autoclaved for 15, 20 and 30 minutes at 132 °C and 2.6 bar. When 15-minute sterilization was used, one out of 16 drills was contaminated with Pseudomonas aeruginosa, while the other 15 drills were sterile. Extended cycle sterilization in autoclave lasting for 20 and 30 minutes resulted in 100% sterility of all drills tested. In conclusion, lumened drills should be exposed to extended sterilization times in autoclave. Minimal recommended time for sterilization of lumened drills is 20 minutes.

Infection after Constrained Condylar Knee Arthroplasty: Incidence and microbiological findings in 100 consecutive complex primary and revision total knee arthroplasties

Background: To report incidence, microbiological findings, and treatment outcome of prosthetic joint infection (PJI) after constrained condylar knee arthroplasty.

Methods: Retrospective study of 100 consecutive complex primary and revision total knee arthroplasties operated with constrained condylar knee arthroplasties between February 2006 and October 2015 at a single institution. Demographic and surgical data were registered, as well as data regarding infection, microbiology and treatment. Follow-up median 43 months; SD 32.

Results: The overall incidence of acute postoperative PJI was low (3/100). 1/33 (3%), 1/ 45 (2%), and 1/22 (5%), following primary complex TKA, aseptic revisions, and septic revisions, respectively. The incidence of late acute hematogenous PJI was 5/100. 1/33 (3%),1/45 (2%), and 3/22 (14%) following primary complex TKA, aseptic revisions, and septic revisions, respectively. Late acute hematogenous infections were associated with a lower success rate of treatment with debridement and implant retention compared with acute postoperative PJIs, 1/5 versus 2/3.

Conclusion: The risk of late acute hematogenous infections seems increased. Multiple previous surgery, poor soft tissue, and large metal implants may contribute to an increased lifelong susceptibility for bacteremias to cause PJIs.

Treatment of Prosthetic Joint Infection with Debridement, Antibiotics and Irrigation with Implant Retention - a Narrative Review

Prosthetic joint infection usually requires combined medical and surgical therapy. While revision surgery is widely considered to be the gold standard surgical procedure, debridement, antibiotics and irrigation with implant retention is a very appealing alternative. There is however great controversy regarding its real worth with success rates ranging from 0% to over 90%. A number of different patient and host related variables as well as specific aspects of surgical and medical management have been described as relevant for the final outcome. Along this paper, the authors will provide the readers with a critical narrative review of the currently available literature while trying to provide concise and practical treatment recommendations regarding adequate patient selection criteria, proper surgical technique and optimal antibiotic therapy.

Outcomes following debridement, antibiotics and implant retention in the management of periprosthetic infections of the hip: a review of cohort studies

AIMS

The aims of the study were to review and analyse the reported series of debridement, antibiotics and implant retention (DAIR) in the management of infected total hip arthroplasties (THAs) to establish the overall success and the influencing factors.

PATIENTS AND METHODS

Using a standardised recognised study protocol, meta-analysis of observational studies in epidemiology guidelines, a comprehensive review and analysis of the literature was performed. The primary outcome measure was the success of treatment. The search strategy and inclusion criteria which involved an assessment of quality yielded 39 articles for analysis, which included 1296 patients.

RESULTS

The proportion of success following DAIR in the management of an infected THA appeared to improve after 2004 with a pooled mean proportion of success of 72.2%. For all reported series, from 1977 onwards, there was improved success with early debridement (< 7 days; 75.7%) and exchange of modular components (77.5%). There was a statistically non-significant improvement if debridement was performed within four weeks of the initial procedure (73.0%).

CONCLUSION

The reported success following DAIR has improved since 2004. The only determinants of outcome which we found were the timing of debridement after the onset of symptoms of infection and the exchange of modular components. Cite this article: Bone Joint J 2017;99-B:1488-66.

The Not-So-Good Prognosis of Streptococcal Periprosthetic Joint Infection Managed by Implant Retention: The Results of a Large Multicenter Study

BACKGROUND.

Streptococci are not an infrequent cause of periprosthetic joint infection (PJI). Management by debridement, antibiotics, and implant retention (DAIR) is thought to produce a good prognosis, but little is known about the real likelihood of success.

METHODS.

A retrospective, observational, multicenter, international study was performed during 2003-2012. Eligible patients had a streptococcal PJI that was managed with DAIR. The primary endpoint was failure, defined as death related to infection, relapse/persistence of infection, or the need for salvage therapy.

RESULTS.

Overall, 462 cases were included (median age 72 years, 50% men). The most frequent species was Streptococcus agalactiae (34%), and 52% of all cases were hematogenous. Antibiotic treatment was primarily using β-lactams, and 37% of patients received rifampin. Outcomes were evaluable in 444 patients: failure occurred in 187 (42.1%; 95% confidence interval, 37.5%-46.7%) after a median of 62 days from debridement; patients without failure were followed up for a median of 802 days. Independent predictors (hazard ratios) of failure were rheumatoid arthritis (2.36), late post-surgical infection (2.20), and bacteremia (1.69). Independent predictors of success were exchange of removable components (0.60), early use of rifampin (0.98 per day of treatment within the first 30 days), and long treatments (≥21 days) with β-lactams, either as monotherapy (0.48) or in combination with rifampin (0.34).

CONCLUSIONS.

This is the largest series to our knowledge of streptococcal PJI managed by DAIR, showing a worse prognosis than previously reported. The beneficial effects of exchanging the removable components and of β-lactams are confirmed and maybe also a potential benefit from adding rifampin.

Staphylococcus aureus soft tissue infection may increase the risk of subsequent staphylococcal soft tissue infections

BACKGROUND

Staphylococcus aureus is the most common cause of soft tissue infections. It is unknown, however, if a patient who has had such an infection is at greater risk for future soft tissue infections with S. aureus.

METHODS

We conducted an epidemiological survey of adult patients hospitalized in the only public hospital in Geneva for treatment (usually combined surgical and medical) of a soft tissue infection caused by S. aureus. By reviewing nursing and medical records from the emergency department and hospital wards, we assessed whether or not they developed any other soft tissue infections (excluding a recurrence) after or before the index one.

RESULTS

Among 1023 index episodes of soft tissue infections, 670 (65%) were caused by S. aureus, of which 47 were caused by methicillin-resistant strains (30 healthcare-associated and 17 community-acquired). The patients' median age was 51 years and 334 (34%) were immune-compromised. The median time span between the patient's first and last consultation (for any reason) in our hospital was 21.4 years (interquartile range, 10-30 years). In addition to their index infection, 124 patients (12%) developed a new nosocomial or community-acquired soft tissue infection. Among the index cases with an S. aureus infection, 92 (14%) had another soft tissue infection, compared to 32 (9%) who had a non-staphylococcal index infection (Pearson-χ²-test; p=0.03). Similarly, patients with an index S. aureus infection, compared to those with a non-S. aureus infection, had a higher rate of another soft tissue infection caused by S. aureus (χ²-test; p<0.01). In multivariate analysis, an index infection due to S. aureus shows a high association to further S. aureus soft tissue infections (logistic regression; odds ratio 2.5, 95% confidence interval 1.4-4.6).

CONCLUSION

Among adult patients hospitalised for a soft tissue infection, those infected with S. aureus (compared with other pathogens) may be at higher risk of a subsequent soft tissue infection, particularly with S. aureus.

High failure rates in treatment of streptococcal periprosthetic joint infection

Aims

To investigate the outcomes of treatment of streptococcal periprosthetic joint infection (PJI) involving total knee and hip arthroplasties.

Patients and Methods

Streptococcal PJI episodes which occurred between January 2009 and December 2015 were identified from clinical databases. Presentation and clinical outcomes for 30 streptococcal PJIs in 30 patients (12 hip and 18 knee arthroplasties) following treatment were evaluated from the medical notes and at review. The Kaplan-Meier survival method was used to estimate the probability of infection-free survival. The influence of the biofilm active antibiotic rifampin was also assessed.

Results

The infection was thought to have been acquired haematogenously in 16 patients and peri-operatively in 14. The median follow-up time for successfully treated cases was 39.2 months (12 to 75), whereas failure of the treatment occurred within the first year following treatment on every occasion. The infection-free survival at three years with 12 patients at risk was 59% (95% confidence interval 39% to 75%). Failure of the treatment was observed in ten of 22 PJIs (45%) treated with a two-stage revision arthroplasty, two of six (33%) treated by debridement and prosthesis retention, and in neither of the two PJIs treated with one-stage revision arthroplasty. Streptococcal PJI treated with or without rifampin included in the antibiotic regime showed no difference in treatment outcome (p = 0.175).

Conclusion

The success of treatment of streptococcal PJI in our patient cohort was poor (18 of 30 cases, 59%). New therapeutic approaches for treating streptococcal PJI are needed. Cite this article: Bone Joint J 2017;99-B:653–9.

Debridement and implant retention in the management of hip periprosthetic joint infection: outcomes following guided and rapid treatment at a single centre

AIMS

To analyse the effectiveness of debridement and implant retention (DAIR) in patients with hip periprosthetic joint infection (PJI) and the relationship to patient characteristics. The outcome was evaluated in hips with confirmed PJI and a follow-up of not less than two years.

PATIENTS AND METHODS

Patients in whom DAIR was performed were identified from our hip arthroplasty register (between 2004 and 2013). Adherence to criteria for DAIR was assessed according to a previously published algorithm.

RESULTS

DAIR was performed as part of a curative procedure in 46 hips in 42 patients. The mean age was 73.2 years (44.6 to 87.7), including 20 women and 22 men. In 34 hips in 32 patients (73.9%), PJI was confirmed. In 12 hips, the criteria for PJI were not fulfilled and antibiotics stopped. In 41 (89.1%) of all hips and in 32 (94.1%) of the confirmed PJIs, all criteria for DAIR were fulfilled. In patients with exogenous PJI, DAIR was performed not more than three days after referral. In haematogenous infections, the duration of symptoms did not exceed 21 days. In 28 hips, a single debridement and in six hips two surgical debridements were required. In 28 (87.5%) of 32 patients, the total treatment duration was three months. Failure was noted in three hips (9%). Long-term follow-up results (mean 4.0 years, 1.4 to 10) were available in 30 of 34 (88.2%) confirmed PJIs. The overall successful outcome rate was 91% in 34 hips, and 90% in 30 hips with long-term follow-up results.

CONCLUSION

Prompt surgical treatment with DAIR, following strict diagnostic and therapeutic criteria, in patients with suspected periprosthetic joint infection, can lead to high rates of success in eradicating the infection. Cite this article: Bone Joint J 2017;99-B:330-6.

Distribution characteristics of Staphylococcus spp. in different phases of periprosthetic joint infection: A review

Periprosthetic joint infection (PJI) is a devastating condition and Staphylococcus spp. are the predominant pathogens responsible, particularly coagulase-negative staphylococci (CoNS) and Staphylococcus aureus. The aim of the present systematic review was to evaluate the distribution characteristics of specific Staphylococcus spp. in different PJI phases, reveal the effect of pathogens' feature on their distribution and suggest recommendations for antibiotic treatment of Staphylococcal PJI. The present systematic review was performed using PubMed and EMBASE databases with the aim to identify existing literature that presented the spectrum of Staphylococcus spp. that occur in PJI. Once inclusion and exclusion criteria were applied, 20 cohort studies involving 3,344 cases in 3,199 patients were included. The predominant pathogen involved in PJI was indicated to be CoNS (31.2%), followed by S. aureus (28.8%). This trend was more apparent in hip replacement procedures. In addition, almost equal proportions of CoNS and S. aureus (28.6 and 30.0%, respectively) were indicated in the delayed phase. CoNS (36.6%) were the predominant identified organism in the early phase, whereas S. aureus (38.3%) occurred primarily in the late phase. In PJI caused by S. aureus, the number of cases of methicillin-sensitive Staphylococcus aureus (MSSA) was ~2.5-fold greater than that of methicillin-resistant Staphylococcus aureus (MRSA). MRSA occurred predominantly in the early phase, whereas MSSA was largely observed in the delayed and late phases. With regards to antibiotic treatment, the feature of various pathogens and the phases of PJI were the primary considerations. The present review provides useful information for clinical practice and scientific research of PJI.

Aggressive Early Debridement in Treatment of Acute Periprosthetic Joint Infections After Hip and Knee Replacements

BACKGROUND

Periprosthetic Joint Infection Remains a Dreaded Complication After Hip and Knee Replacement Surgery. Treatment Options for Acute Postoperative and Acute Hematogenous Infections Include Arthroscopic or Open Debridement With Retention or Exchange of the Prostheses. This Review Article Aims to Summarize the Evidence for Management of Acute Postoperative And Acute Hematogenous Infections.

METHODS

A Systematic Literature Search Was Performed Using a Computer-based Search Engine Covering Medline (OvidSP), PubMed Database (U.S. National Library of Medicine, National Institutes of Health), Embase, Web of Science, Cochrane and Google Scholar for Relevant Articles.

RESULTS

Common Themes Around Treatment of Acute Postoperative and Acute Hematogenous Infections Discussed in this Review Include the Timing of Intervention, Description of the Optimal Procedure and How we Perform it at our Institution, the Role of Arthroscopic Debridement, Most Commonly Isolated Micro-organisms and Prognostic Factors for Infection Control.

CONCLUSION

Success in Treating Acute Postoperative and Acute Hematogenous Infections Depends on Early Diagnosis and Aggressive Surgical Debridement Combined With Effective Antibiotic Therapy.

Management of Resistant, Atypical and Culture-negative Periprosthetic Joint Infections after Hip and Knee Arthroplasty

BACKGROUND

Periprosthetic joint infection (PJI) is a devastating complication following lower extremity total joint arthroplasty (TJA). It is a leading cause of morbidity and revision following TJA. As such, PJI is a significant driver of healthcare costs. The prevalence of PJI related to resistant and atypical organisms is increasing, and approximately 10-30% of PJIs are culture-negative. The purpose of this review is to summarize the current epidemiology, diagnostics, and management of PJI associated with resistant and atypical pathogens and of culture-negative PJIs.

METHODS

The published literature related to the epidemiology, diagnosis, and management of atypical, drug-resistant, and culture-negative PJI is reviewed.

RESULTS

The clinical diagnosis of PJI is often challenging, particularly when pathogens are fastidious or when antibiotics have been administered empirically. Molecular diagnostic studies, such as synovial α-defensin, may provide rapid, accurate identification of PJI, even in the setting of concurrent antibiotics administration or systemic inflammatory disease. Once PJI is diagnosed, two-stage exchange arthroplasty remains the gold standard for treating PJI with resistant microorganisms, since there is a high rate of treatment failure with irrigation and debridement and with one-stage exchange arthroplasty.

CONCLUSION

Additional research is needed to define the optimal treatment of PJIs associated with rare pathogens, such as fungi and mycobacteria. There is a need for inexpensive, reliable tests that rapidly detect specific microbial species and antimicrobial susceptibilities. Additional research is also required to define the specific organisms, clinical scenarios, surgical techniques, and antimicrobial regimens that allow for reproducible treatment success with prosthetic retention strategies.

Clinical and epidemiological differences between implant-associated and implant-free orthopaedic infections

PURPOSE

Although there have been many publications regarding the risk factors for implant-associated orthopaedic infections, none have investigated how clinical presentations and epidemiology may differ between infections with and without osteosynthetic material.

METHODS

We pooled clinical data from several databases of adult patients with orthopaedic infections hospitalized at Geneva University Hospitals from January 2004 to December 2014.

RESULTS

Among 2740 episodes of orthopaedic infections, 76% were implant-free osteoarticular or soft tissue infections. Among the 665 (24% of the total episodes) infections that involved osteosynthetic material, 319 (49%) were total joint arthroplasties, 143 single plates, and 50 single nails. The remainders were mixed implant infections, pins, wires, screws, cerclages or spondylodeses. The implant-associated, compared to the implant-free, infections were significantly more frequently associated with female sex, older age, bacteraemia and skin commensal infections, e.g. coagulase-negative staphylococci, corynebacteria or propionibacteria. In contrast, implant-associated infections were significantly less frequently associated with immune suppression, abscess formation, infections due to Staphylococcus aureus or streptococci, polymicrobial pathogens and foot infections. The serum CRP levels at admission were similar (median 82 vs. 75 mg/L).

CONCLUSIONS

Compared to implant-free infections, implant-associated orthopaedic infections are more likely monomicrobial, bacteraemic and due to skin commensals. They involve more often female and older patients, but are less often associated with immune suppression, abscess formation and foot infections.

Outcome of patients with streptococcal prosthetic joint infections with special reference to rifampicin combinations

BACKGROUND

Outcome of patients with streptococcal prosthetic joint infections (PJIs) is not well known.

METHODS

We performed a retrospective multicenter cohort study that involved patients with total hip/knee prosthetic joint (THP/TKP) infections due to Streptococcus spp. from 2001 through 2009.

RESULTS

Ninety-five streptococcal PJI episodes (50 THP and 45 TKP) in 87 patients of mean age 69.1 ± 13.7 years met the inclusion criteria. In all, 55 out of 95 cases (57.9 %) were treated with debridement and retention of the infected implants with antibiotic therapy (DAIR). Rifampicin-combinations, including with levofloxacin, were used in 52 (54.7 %) and 28 (29.5 %) cases, respectively. After a mean follow-up period of 895 days (IQR: 395-1649), the remission rate was 70.5 % (67/95). Patients with PJIs due to S. agalactiae failed in the same proportion as in the other patients (10/37 (27.1 %) versus 19/58 (32.7 %); p = .55). In the univariate analysis, antibiotic monotherapy, DAIR, antibiotic treatments other than rifampicin-combinations, and TKP were all associated with a worse outcome. The only independent variable significantly associated with the patients' outcomes was the location of the prosthesis (i.e., hip versus knee) (OR = 0.19; 95 % CI 0.04-0.93; p value 0.04).

CONCLUSIONS

The prognosis of streptococcal PJIs may not be as good as previously reported, especially for patients with an infected total knee arthroplasty. Rifampicin combinations, especially with levofloxacin, appear to be suitable antibiotic regimens for these patients.

Risk of Reinfection After Treatment of Infected Total Knee Arthroplasty

BACKGROUND

The purpose of this study was to determine the incidence of subsequent reinfections after initial treatment of an infected total knee arthroplasty, identify risk factors leading to reinfection, and compare results among the varying treatment modalities.

METHODS

A total of 1,493,924 primary TKA patients were identified from the Medicare data between October 1, 2005, and December 31, 2011. Patients who encountered periprosthetic joint infection (PJI) after TKA were identified using International Classification of Diseases, Ninth Revision, Clinical Modification code 996.66. The risk of subsequent PJI was stratified based on the first-line treatment and compared between the various first-line treatment groups.

RESULTS

A total of 16,622 patients (1.1%) were diagnosed with PJI. The Kaplan-Meier risk of PJI was 0.77% at 1 year and 1.58% at 6 years. Age (P < .001), Charlson score (P < .001), hospital control (P < .001), race (P = .036), census region (P = .031), gender (P < .001) were identified as risk factors for PJI. Of the PJI patients, 20.8% (n = 2806) were treated with incision and drainage (I&D), 15.9% (n = 2150) treated with I&D and liner exchange, 22.7% (n = 3069) treated with 1-stage revision, 39.7% (n = 5364) treated with 2-stage revision, and 0.98% (n = 132) treated with amputation. After first-line treatment, 26% of patients with PJI had a subsequent PJI. Patients undergoing I&D as a first-line treatment had the highest risk of reinfection, with risks of 28.2% at 1 year and 43.2% at 6 years. One-stage revision patients had 33.9% greater adjusted risk of reinfection than 2-stage revision patients (P < .001).

CONCLUSION

Two-stage reimplantation, despite 19% recurrence, had the highest success rate. Given the higher failure rates of I&D and single-stage revisions, guidelines need to be established for their specific indications.

Administration of antibiotic agents before intraoperative sampling in orthopedic infections alters culture results

Many physicians and surgeons think that prescribing antibiotics before intraoperative sampling does not alter the microbiological results.

METHODS

Case-control study of adult patients hospitalized with orthopedic infections.

RESULTS

Among 2740 episodes of orthopedic infections, 1167 (43%) had received antibiotic therapy before surgical sampling. Among these, 220 (19%) grew no pathogens while the proportion of culture-negative results in the 2573 who had no preoperative antibiotic therapy was only 6%. By multivariate analyses, pre-operative antibiotic exposure was associated with significantly more culture-negative results (odds ratio 2.8, 95% confidence interval 2.1-3.7), more non-fermenting rods and skin commensals (odds ratio 2.8 and 3.0, respectively). Even a single pre-operative dose of antibiotic was significantly associated with subsequent culture-negative results (19/93 vs. 297/2350; χ²-test, p = 0.01) and skin commensals (17/74 vs. 274/2350; p = 0.01) compared to episodes without preceding prophylaxis.

CONCLUSIONS

Prior antibiotic use, including single-dose prophylactic administrations, is three-fold associated with culture-negative results, non-fermenting rods and resistant skin commensals.

Irrigation and debridement for periprosthetic infections of the hip and factors determining outcome

PURPOSE

Our purpose was to identify the success rate and factors predicting outcome of irrigation and debridement (I&D) in patients with deep periprosthetic joint infection (PJI) of the hip.

METHODS

We retrospectively reviewed clinical characteristics of patients with deep PJI after primary/revision total hip arthroplasty (THA) between January 2000 and May 2013 treated with I&D. Implant retention was the outcome of interest. Sixty patients (29 men and 31 women; mean age 64.9 years) were identified. Mean follow-up was 59 months (range, 12-168).

RESULTS

The implants were retained in 42 patients (70%). Failure of I&D treatment correlated with duration of symptoms >five days (p <0.001) and obesity [body mass index (BMI) ≥ 30)] (p = 0.0289). Treatment outcome was affected by the type of pathogen (p = 0.0482), with patients with methicillin-resistant staphylococci having significantly lower odds of success.

CONCLUSIONS

I&D can be a feasible option in THA patients presenting with acute deep PJI. Duration of symptoms >five days, isolation of methicillin-resistant staphylococci and obesity should be taken into consideration in pre-operative decision making.

Coating with a novel gentamicinpalmitate formulation prevents implant-associated osteomyelitis induced by methicillin-susceptible Staphylococcus aureus in a rat model

PURPOSE

Implant-associated osteomyelitis still represents a demanding challenge due to unfavourable biological conditions, bacterial properties and incremental resistance to antibiotic treatment. Therefore different bactericide or bacteriostatic implant coatings have been developed recently to control local intramedullary infections. Controlled local release of gentamicin base from a highly lipophilic gentamicin palmitate compound achieves extended intramedullary retention times and thus may improve its bactericide effect.

METHODS

Forty male Sprague-Dawley rats were divided into two groups receiving an intramedullary femoral injection of 10(2) colony-forming units (CFU) of a common methicillin susceptible Staphylococcus aureus strain (MSSA Rosenbach) and either an uncoated femur nail (Group I) or a nail coated with gentamicin palmitate (Group II). Animals were observed for 28 and 42 days. Serum haptoglobin and relative weight gain were assessed as well as rollover cultures of explanted femur nails and histological scores of periprosthetic infection in dissected femurs.

RESULTS

Implants coated with gentamicin palmitate significantly reduced periprosthetic bacterial growth as well as signs of systemic inflammation compared with uncoated implants.

CONCLUSIONS

Gentamicin palmitate appears to be a viable coating for the prevention of implant-associated infections. These findings will have to be confirmed in larger animal models as well as in clinical trials.