Is the prognosis the same for periprosthetic joint infections due to Staphylococcus aureus versus coagulase-negative staphylococci? A retrospective study of 101 patients with 2-year minimum follow-up

Prosthetic Knee Infection With Coagulase-Negative Staphylococcus: A Harbinger of Poor Outcomes

BACKGROUND

Coagulase-negative staphylococci (CoNS) are biofilm-producing pathogens whose role in periprosthetic joint infection (PJI) is increasing. There is little data on the prognosis and treatment considerations in the setting of PJI. We sought to evaluate the clinical characteristics, outcomes, and complications in these patients.

METHODS

This is a retrospective cohort study of adult patients at a single tertiary medical center from 2009 to 2020 with culture-proven CoNS PJI after total knee arthroplasty, as diagnosed by Musculoskeletal Infection Society criteria. The primary outcome was treatment success, with failure defined as recurrent CoNS PJI, recurrent PJI with a new pathogen, and/or chronic oral antibiotic suppression at one year postoperatively.

RESULTS

We identified 55 patients with a CoNS total knee arthroplasty PJI with a mean follow-up of 29.8 months (SD: 16.3 months). The most commonly isolated organism was Staphylococcus epidermidis (n = 36, 65.5%). The overall prevalence of methicillin resistance was 63%. Surgical treatment included surgical debridement, antibiotics, and implant retention in 25 (45.5%) cases and two-stage revision (22 articulating and eight static antibiotic-impregnated spacers). At one-year follow-up, only 47% of patients had successful management of their infection. The surgical debridement, antibiotics, and implant retention cohort had the higher rate of treatment failure (60.0%) compared to two-stage revision (46.7%).

CONCLUSION

These results indicate a poor rate of success in treating CoNS PJI. This likely represents the interplay of inherent virulence through biofilm formation and decreased antibiotic efficacy.

Differences in Diagnostic Properties Between Standard and Enrichment Culture Techniques Used in Periprosthetic Joint Infections

BACKGROUND

Culture-negative infections can complicate the diagnosis and management of orthopedic infections, particularly periprosthetic joint infections (PJIs). This study aimed to identify differences in rate of detection of infection and organisms between cultured using standard and enriched methods.

METHODS

This retrospective, cross-sectional study evaluated PJI samples obtained between January 2013 and December 2017 at Yokohama City University Hospital. Samples were assessed using standard and enrichment culture techniques. White blood cell counts, C-reactive protein levels, type of microorganism (coagulase-positive or coagulase-negative), and methicillin-resistant Staphylococcus were investigated.

RESULTS

A total of 151 PJI samples were included in the analysis; of these, 68 (45.0%) were positive after standard culture while 83 (55.0%) were positive only after enrichment culture. The mean white blood cell counts and C-reactive protein levels were significantly lower in the enrichment culture group than in the standard culture group (P < .01). The rate of methicillin-resistant Staphylococcus and coagulase-negative Staphylococci was significantly higher in the enrichment culture group than in the standard culture group (P < .01).

CONCLUSION

The enrichment culture method has a higher rate of detection of infection than standard culture techniques and should, therefore, be considered when diagnosing orthopedic infections, particularly PJI.

Two-stage revision arthroplasty for coagulase-negative staphylococcal periprosthetic joint infection of the hip and knee

BACKGROUND

Periprosthetic joint infections (PJIs) are frequently caused by coagulase-negative Staphylococci (CoNS), which is known to be a hard-to-treat microorganism. Antibiotic resistance among causative pathogens of PJI is increasing. Two-stage revision is the favoured treatment for chronic CoNS infection of a hip or knee prosthesis. We hypothesised that the infection eradication rate of our treatment protocol for two-stage revision surgery for CoNS PJI of the hip and knee would be comparable to eradication rates described in the literature.

AIM

To evaluate the infection eradication rate of two-stage revision arthroplasty for PJI caused by CoNS.

METHODS

All patients treated with two-stage revision of a hip or knee prosthesis were retrospectively included. Patients with CoNS infection were included in the study, including polymicrobial cases. Primary outcome was infection eradication at final follow-up.

RESULTS

Forty-four patients were included in the study. Twenty-nine patients were treated for PJI of the hip and fifteen for PJI of the knee. At final follow-up after a mean of 37 mo, recurrent or persistent infection was present in eleven patients.

CONCLUSION

PJI with CoNS can be a difficult to treat infection due to increasing antibiotic resistance. Infection eradication rate of 70%-80% may be achieved.

Comparison between the Staphylococci aureus and coagulase-negative staphylococci infected total joint arthroplasty treated by two-stage revision: A retrospective study with two year minimum follow-up

BACKGROUND

Staphylococcus species are major pathogens of peri-prosthetic joint infection (PJI). Coagulase-positive staphylococci and coagulase-negative staphylococci have different intrinsic virulences. However, few studies have specifically compared the clinical manifestations and two-stage revision outcomes of PJI caused by these two species.

METHODS

We retrospectively collected 260 arthroplasty patients who underwent a two-stage revision because of PJI from January 2003 to June 2015 in our institute because of PJI. Sixty-four patients (36 hips and 28 knees) and 23 patients (13 hips and 10 knees) were infected by coagulase-negative staphylococci (CoNS) and SA, respectively.

RESULTS

The preoperative mean ESR value of the SA group was higher than that of the CoNS group (median, 60.9 VS 35.9; P < 0.001). Seventeen (73.9%) of the 23 SA infected patients had a sinus tract, while only 12 (18.8%) of the 64 CoNS-infected patients had this symptom (73.9% VS 18.8%; P < 0.001). At the time of follow-up, 58 (90.6%) of the 64 CoNS-infected patients had successfully controlled the infection. In the SA group, 20 (87.0%) patients ultimately acquired successful control (90.6% VS 87.0%; P = 0.923). Surgical history was identified as a potential risk factor (OR = 6.2, 95%CI 1.17-32.4) for prognosis when potential covariates were adjusted.

CONCLUSIONS

SA infection has a higher ESR value and a more frequent occurrence of sinus tract. The infection control rate of the two-stage revision protocol was close to 90% for both SA and CoNS species, and there is no statistically significant difference in the eradication rate of infection between the SA and CoNS groups. Surgical history may be a good predictor of failure for PJI patients treated with two-stage revision.

Preliminary results of a novel spacer technique in the management of septic revision hip arthroplasty

INTRODUCTION

Mechanical failure due to dislocation, fracture and acetabular wear is a major complication associated with the use of spacers in the management of periprosthetic joint infection (PJI). We have developed a novel custom-made spacer in the setting of two-stage septic revision hip arthroplasty and present the preliminary results of our technique.

MATERIALS AND METHODS

Between May 2015 and November 2017, 30 patients underwent hip revision using the ENDO spacer technique in the setting of a two-stage septic exchange arthroplasty. The technique involves the dual mobility liner and the downsized stainless cemented straight stem in combination with antibiotic-loaded PMMA bone cement. The primary outcome measure was the overall spacer complication rate, particularly spacer dislocation. Furthermore, functional outcome using the Harris Hip Score (HHS) before spacer implantation and prior re-implantation was evaluated.

RESULTS

The mean age of the patients was 69.8 years (range from 45 to 85; SD = 9.9 years). No microorganisms were preoperatively found in 23 (76.7%) cases. Successful re-implantation was performed in all patients after a mean spacer duration time of 53.6 days (range 14-288 days; SD = 48.2). Spacer-related complications occurred in only two patients (6.7%). The HHS significantly improved from 34.0 (range 3-62; SD = 15.1) to 48.1 (range 11-73; SD = 15.7) (p = 0.0008).

CONCLUSIONS

The ENDO spacer surgical technique is a feasible option in the treatment of periprosthetic joint infection (PJI), with a low dislocation rate. Furthermore, it allows early mobilization with the possibility of full-weight bearing.

An often-unrecognized entity as cause of recurrent infection after successfully treated two-stage exchange arthroplasty: hematogenous infection

INTRODUCTION

Reinfection after two-stage exchange arthroplasty is a difficult clinical scenario with limited data on adequate treatment algorithms. Beside the possibility of treatment failure and a new intraoperative infection at the time of reimplantation, hematogenous seeding could play an up to date underestimated crucial role as another cause of an infection after two-stage exchange. The aim of this study was to evaluate its incidence and treatment possibilities in a prospectively followed case series.

METHODS

All consecutive hip and knee periprosthetic joint infection cases (93 hips and 89 knees) treated according to a standardized diagnostic and therapeutic algorithm at our institution with a two-stage exchange arthroplasty from 2013 to 2015 were included and followed prospectively to identify recurrent infections due to hematogenous seeding.

RESULTS

Six percent from our septic revision hip and knee arthroplasties (11 of 182, including 5 hips and 6 knees) were identified with a hematogenous reinfection after a mean follow-up of 31.8 months (range 14-48 months). The mean time to reinfection after reimplantation was 12.2 months (range 3.1-35.1). In all but two cases was the causative microorganism different than isolated at the time of initial two-stage exchange. In 5 of 11 patients, the primary focus of infection was identified.

CONCLUSION

Hematogenous infection after a successful two-stage exchange arthroplasty is a rare but very important cause of a reinfection. With our work, we aim at raising the awareness for this entity and recommend consideration of irrigation and debridement with implant retention in these cases, as well as possibly the identification of a primary infection source.

Diagnostic accuracy of synovial fluid, blood markers, and microbiological testing in chronic knee prosthetic infections

INTRODUCTION

This retrospective study was undertaken to define cut-off values for synovial fluid (SF) leukocyte count and neutrophil percentage for differentiating aseptic failure and periprosthetic joint infection (PJI) and to evaluate the diagnostic accuracy of blood inflammatory markers, and microbiological testing according to the criteria proposed by the International Consensus Meeting (ICM) of Philadelphia.

METHODS

All patients who underwent revision total knee arthroplasty from January 2010 to July 2015 were included: we identified and classified 31 PJIs and 136 aseptic joints. The diagnostic performance of single test was assessed by receiver operating characteristic curve analyses. The sensitivity and specificity were calculated for each of the cut-off values and the area under the curve (AUC) was calculated.

RESULTS

The median SF leukocyte count as well as the neutrophil percentage and inflammatory markers were significantly higher in patients with PJI than in those with aseptic failure (p < 0.001). A leukocyte count of > 2.8 × 10³/μL had a sensitivity of 83.8% and a specificity of 89.7% whereas a neutrophil percentage of > 72% yielded a marginally higher sensitivity of 84% and a specificity of 91%. Applying the ICM criteria we found a significant correlation between all these diagnostic measures and PJI (p < 0.001) except for a single positive culture. The most accurate criterion of the ICM was the synovial neutrophil differential (AUC = 0.89; 95% CI 0.81-0.97), followed by SF leukocyte count (AUC = 0.86; 95% CI 0.78-0.94), increased inflammatory markers (AUC = 0.85; 95% CI 0.76-0.93), and two positive periprosthetic cultures (AUC = 0.84; 95% CI 0.73-0.94). The presence of sinus tract communicating with the joint and a single positive culture showed unfavourable diagnostic accuracy (AUC = 0.60, 95% CI 0.47-0.72; AUC = 0.49, 95% CI 0.38-0.61, respectively) CONCLUSIONS: The present study highlights the adequate ability of fluid cell count and neutrophil differential to distinguish between PJI and aseptic loosening. The clinical utility of fluid analysis in diagnosing infection can be improved by evaluation of other diagnostic criteria.

LEVEL OF EVIDENCE

Level I Diagnostic Study.

How Many Cultures Are Necessary to Identify Pathogens in the Management of Total Hip and Knee Arthroplasty Infections?

BACKGROUND

Identification of the infecting organism is critical to the successful management of deep prosthetic joint infections about the hip and the knee. However, the number of culture specimens and which culture specimens are best to identify these organisms is unknown.

METHODS

We evaluated 113 consecutive patients with infected total hip and total knee arthroplasties and correlated the type of culture specimen and number of specimens taken during surgery to the likelihood of a positive culture result. From these data, we subsequently developed a model to maximize culture yield at the time of surgical intervention. After exclusions, 74 patients meeting the Musculoskeletal Infection Society criteria were left for final analysis.

RESULTS

From this cohort, 63 of 74 patients had a positive culture result (85%). The odds of a fluid culture result being positive was 35 of 47 (0.75), whereas the likelihood of tissue cultures yielding a positive result was 164 of 245 (0.67; P = .313). The sample designated "best culture" specimen was the only culture with a positive result in 1 of 48 cases in which a best culture was identified. The optimal number of cultures needed to yield a positive test result was 4 (specificity = 0.61 and sensitivity = 0.63). Increasing the number of samples increases sensitivity but reduces specificity.

CONCLUSION

A minimum of 4 tissue cultures from representative areas is necessary to maximize the chance of identifying the infecting organism during management of the infected total hip and total knee arthroplasties. The designation of the best culture specimen for additional testing is arbitrary and may not be clinically efficacious.