Development of antibiotic resistance in periprosthetic joint infection after total knee arthroplasty

Success rate of single versus multiple debridement, antibiotics, and implant retention (DAIR) in hip and knee periprosthetic joint infection: a systematic review and meta-analysis

PURPOSE

This systematic review aimed to compare outcomes between multiple and single debridement, antibiotics, and implant retention (DAIR) procedures for early periprosthetic joint infection (PJI) in hip and knee arthroplasty.

METHODS

Four databases were searched from inception till January 2024 for original studies investigating the outcomes of multiple DAIR in hip and knee PJI. The primary outcome was the success rate in eradicating joint infection. This review was conducted per PRISMA guidelines.

RESULTS

A total of 9 observational studies with 1104 participants were included, with a mean age and BMI of 58.37 years (95%CI: 25.77-90.98) and 31.43 kg/m2 (95%CI: 28.89-34.98), respectively. The mean follow-up period was 58.37 months (95%CI: 25.77-90.98), and the average MINORS score assigned to the review was 17.6 ± 3.46, indicating a low overall risk of bias. An equivalent success rate between single and double DAIR was observed, at 67% (95%CI: 64-71%) and 70% (95%CI: 48-86%), respectively, with no statistically significant difference between the two treatment modalities (p = 0.740). Additionally, the success rate for triple DAIR ranged from 50 to 60%.

CONCLUSION

This study suggests that double DAIR is a valid treatment option for acute PJI after TKA and THA, with a success rate comparable to single DAIR (70% vs. 67%, p = 0.740). Triple DAIR achieved success rates ranging from 50 to 60%. However, caution is warranted when interpreting these results due to heterogeneity in host comorbidity factors, DAIR protocols, and antibiotic regimens.

LEVEL OF EVIDENCE

Therapeutic, Level III.

The Microbiology of Knee Prosthetic Joint Infection and its Influence on Persistent Infection

Periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) is a severe complication causing a significant burden. The study aims were to establish the epidemiology of microorganisms in TKA PJI, the rate of persistent infection requiring further surgery, and the risk factors for this. Microbiological specimens between June 2002 and March 2017 at five regional hospital sites were identified with revision TKA procedures in the National Joint Replacement Registry. The time between procedures, type of revision strategy, and any subsequent further revision operations were collected. At minimum 2-year follow-up, 174 revision TKA were identified, with a mean patient age of 69 ± 11 years. A broad range of pathogens were identified. Fifty cases (29%) had persistent infection requiring at least one further operative procedure, 13 cases required 3 or more. Coagulase-negative Staphylococcus species (CNS) was seen most with failed surgery, polymicrobial infections also posing a significant risk factor. The best chance of a successful PJI surgical strategy was < 12 months from primary TKA, with the greatest risk between 3 and 5 years (p < 0.05). Younger age significantly increased the risk of further surgery (p < 0.05). Management varied; 103 (59%) debridement, antibiotic therapy and implant retention, with further surgery in 29%; 45 (17%) single-stage revision, with further surgery in 13%; and 26 (15%) two-stage revision, with further surgery in 12%. This study presents the most common causative pathogens for PJI in TKA, and the high rate of persistent infection after initial revision surgery. Risk factors for persistent infection and further revision surgery were polymicrobial and CNS infections, patients who presented between 3 and 5 years following primary TKA, and younger age. This study therefore raises important risk factors and areas for future research to reduce the burden of multiple operations after PJI.

Low Risk of Periprosthetic Joint Infection After Aseptic Revision Total Knee Arthroplasty With Intraosseous Vancomycin

BACKGROUND

Aseptic revisions are the most common reason for revision total knee arthroplasty (rTKA). Previous literature reports early periprosthetic joint infection (PJI) rates after aseptic rTKA to range from 3 to 9.4%. Intraosseous (IO) regional administration of vancomycin has previously been shown to produce high local tissue concentrations in primary and rTKA. However, no data exist on the effect of prophylactic IO vancomycin on early PJI rates in the setting of aseptic rTKA. The aim of this study was to determine the following: (1) what is the rate of early PJI during the first year after surgery in aseptic rTKA performed with IO vancomycin; and (2) how does this compare to previously published PJI rates after rTKA.

METHODS

A consecutive series of 117 cases were included in this study who underwent rTKA between January 2016 and March 2022 by 1 of 2 fellowship-trained adult reconstruction surgeons and received IO vancomycin at the time of surgery in addition to standard intravenous antibiotic prophylaxis. Rates of PJI at 3 months, 1 year, and the final follow-up were evaluated and compared to prior literature.

RESULTS

Follow-up at 3 months was available for 116 of the 117 rTKAs, with 1 lost to follow-up. The rate of PJI was 0% at 3 months postoperatively. Follow-up at 1 year was obtained for 113 of the 117 rTKAs, and the PJI rate remained 0%. The rate of PJI at the final follow-up of ≥ 1 year was 0.88% (95% confidence interval: -0.84 to 2.61). Previous literature reports PJI rates in aseptic rTKA to range from 3 to 9.4%.

CONCLUSIONS

Dual prophylactic antibiotics with IO vancomycin in conjunction with intravenous cephalosporins or clindamycin were associated with a substantial reduction in early PJI compared to prior published literature. These data supplement the early evidence about the potential clinical benefits of IO vancomycin for infection prevention in high-risk cases.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Implementation of Outpatient Parenteral Antimicrobial Therapy (OPAT) in Patients with Complicated Periprosthetic Joint Infections

Periprosthetic joint infections (PJI) are a serious complication of arthroplasty with high morbidity. With growing bacterial resistance and limited disposability of oral antibiotics with sufficient bioavailability, the need for intravenous antibiotic application is raising. This causes long-term hospital stays and rising costs. In the course of transferring procedures into an outpatient setting as well as coping with pressures on hospital capacity, outpatient parenteral antimicrobial therapy (OPAT) can build a bridge for the treatment of such infections.In a single centre analysis, 47 cases treated with OPAT were studied in relation to pathogen, antimicrobial resistance, indication for OPAT and follow up. Furthermore, the patients received an anonymised questionnaire with 4 clusters of interest in terms of internal quality assessment on the success and evaluation of this therapeutic procedure. Special attention was paid to the descriptive analysis of patients with periprosthetic joint infections (n = 30).Between May 2021 and October 2022 out of 47 patients with OPAT, 30 cases with periprosthetic joint infections were identified. For infected hip- and knee arthroplasties, a remarkable spectrum of pathogens was found. In hip infections highly resistant strains of Staphylococcus epidermidis and Enterococci were detected. In knee infections, the pathogens were more susceptible, but however highly virulent Staphylococcus aureus and Streptococci. Difficult to treat, mixed infections were found in both locations. The indication for OPAT was based in half of the cases on the high level of antimicrobial resistance, with availability of only parenteral applicable antibiotics. Further indications were mixed infections and difficult to treat pathogens, with flucloxacillin therapy as well as OPAT as the last therapeutic option. The questionnaire showed 96% patient satisfaction in terms of organisation and acceptance of this kind of therapy. Complications or unexpected outpatient/ hospital treatments were very rare in connection with OPAT. Two thirds of patients reported completion of the treatment. In the clinical follow up (average of 5.7 months), 96.6% of cases were declared free of infection. In one patient the infection persisted.OPAT is a safe and reliable therapeutic option for outpatients to continue parenteral antimicrobial treatment in joint infections. Due to increasing pressure on hospitals in terms of costs and capacity, this therapy offers an alternative to inpatient treatment. The indication for OPAT should be set individually, risk adjusted and not generalised for all patients. The outpatient sector needs financial and structural support for comprehensive roll-out of this treatment in Germany. A further focus should be on the prevention of periprosthetic joint infections. With the knowledge of the expected pathogens and the surgical resources, the standards should be adapted. The choice of the antibiotic should be specified and the intervals of application be shortened, according to the surgical course, in order to yield high levels of agent concentration in the surgical area. Further investigations are required to test the superiority of OPAT versus the oral administration of antibiotics in long-term observations as well as to define the necessary duration of OPAT.

Infection Rates After Aseptic Revision Total Hip Arthroplasty With Extended Oral Antibiotic Prophylaxis

INTRODUCTION

Few US studies have investigated the efficacy of extended oral antibiotic prophylaxis (EOAP) in the prevention of periprosthetic joint infection (PJI) after aseptic revision total hip arthroplasty (R-THA). This study compared PJI rates in aseptic R-THA performed with EOAP with PJI rates in published studies of aseptic R-THA patients not receiving EOAP.

METHODS

Prospectively documented data on 127 consecutive aseptic R-THAs were retrospectively reviewed. Evidence-based perioperative infection prevention protocols were used, and all patients were discharged on 7-day EOAP. Superficial and deep infections at 30 and 90 days postoperatively and at mean latest follow-up of 27.8 months were statistically compared with all US studies reporting the prevalence of PJI after aseptic R-THA. Complications related to EOAP within 120 days of the index procedure also are reported.

RESULTS

No superficial or deep infections were observed at 30 and 90 days postoperatively when 7-day postdischarge EOAP was used. Superficial and deep infection rates were 1.57% (two patients) and 3.15% (four patients) at mean latest follow-up, respectively. Comparisons with published 30-day PJI rates of 1.37% ( P = 0.423) and 1.85% ( P = 0.257) were not statistically significant. Two of four comparisons with published 90-day PJI rates of 3.43% ( P = 0.027) and 5.74% ( P = 0.001) were statistically different. The deep PJI rate of 3.15% at mean latest follow-up was significantly lower than two of three published rates at equivalent follow-up including 10.10% ( P = 0.009) and 9.12% ( P = 0.041). No antibiotic-related complications were observed within 120 days of the index procedure.

DISCUSSION

Study findings possibly support the use of EOAP after aseptic R-THA to prevent catastrophic PJI with revision implants, indicating that the efficacy of EOAP cannot be definitively ruled-in or ruled-out based on available evidence.

Suppressive Antibiotic Therapy After Debridement, Antibiotics, and Implant Retention is Well-Tolerated Without Inducing Resistance: A Multicenter Study

BACKGROUND

Suppressive antibiotic therapy (SAT) after total joint arthroplasty (TJA) debridement, antibiotics, and implant retention (DAIR) maximizes reoperation-free survival. We evaluated SAT after DAIR of acutely infected primary TJA regarding: 1) adverse drug reaction (ADR)/intolerance; 2) reoperation for infection; and 3) antibiotic resistance.

METHODS

Patients who underwent total knee arthroplasty (TKA) or total hip arthroplasty (THA) DAIR for acute periprosthetic joint infection at two academic medical centers from 2015 to 2020 were identified (n = 115). Data were collected on patient demographics, infecting organisms, antibiotics, ADR/intolerances, reoperations, and antibiotic resistances. Median SAT duration was 11 months. Stepwise multivariate logistic regressions were used to identify covariates significantly associated with outcomes of interest.

RESULTS

There were 11.1 and 16.3% of TKA and THA DAIR patients, respectively, who had ADR/intolerance to SAT. Patients prescribed trimethoprim/sulfamethoxazole (P = .0014) or combination antibiotic therapy (P = .0169) after TKA DAIR had increased risk of ADR/intolerance. There was no difference in reoperation-free survival between TKA (83.3%) and THA (65.1%) DAIR (P = .5900) at mean 2.8-year follow-up. Risk of reoperation for infection was higher among TKA Staphylococcus aureus infections (P = .0004) and lower with increased SAT duration (P < .0450). The optimal duration of SAT was nearly 2 years. No cases of antibiotic resistance developed due to SAT.

CONCLUSIONS

Consider SAT after TJA DAIR due to improved reoperation-free survival and favorable safety profile. Prolonged SAT did not induce antibiotic resistance. Use trimethoprim/sulfamethoxazole with caution because of the increased likelihood of ADR/intolerance.

LEVEL OF EVIDENCE

Therapeutic Level III.

Second-Line Antibiotic Agents in Patient-Reported Penicillin or Cephalosporin Allergy Have No Negative Impact on Antibiotic Resistance After Hip and Knee Arthroplasty

BACKGROUND

The aim of the present study was to compare causative bacteria and their antibiotic resistance profiles in patients developing a periprosthetic joint infection (PJI) based on preoperative prophylactic antibiotic regimens in primary total hip (THA) and primary total and unicompartmental knee arthroplasty (TKA/UKA).

METHODS

We reviewed all cases of PJI occurring after primary THA and primary TKA/UKA, between 2011 and 2020 in a tertiary referral hospital. The standard preoperative prophylactic antibiotic for primary joint arthroplasty was cefuroxime and recommended second-line agent was clindamycin. Patients were divided by the replaced joint and analyzed independently.

RESULTS

In the THA group, culture-positive PJI was detected in 61 of 3,123 (2.0%) cefuroxime-administered cases and 6 of 206 (2.9%) noncefuroxime-administered cases. In the TKA/UKA group, culture positive PJI was identified in 21 of 2,455 (0.9%) cefuroxime-administered cases and in 3 of 211 (1.4%) noncefuroxime administered cases. The most commonly isolated bacteria in both groups were coagulase negative staphylococci (CNS). There were no statistically significant differences of pathogen spectrum depending on the preoperative antibiotic regimen detected. Antibiotic resistance of isolated bacteria was significantly different in 4 of 27 (14.8%) analyzed antibiotics in THA and in 3 of 22 (13.6%) analyzed antibiotics in TKA/UKA. In all cohorts, a high occurrence of oxacillin-resistant CNS (50.0 to 100.0%) and clindamycin-resistant CNS (56.3 to 100.0%) has been observed.

CONCLUSION

The use of the second-line antibiotic did not influence the pathogen spectrum or antibiotic resistance. However, an alarmingly high proportion of CNS strains was resistant to clindamycin.

Comparison of outcomes between fungal and non-fungal periprosthetic joint infections in total knee arthroplasty

Aims

Fungal periprosthetic joint infections (PJIs) are rare, but their diagnosis and treatment are highly challenging. The purpose of this study was to investigate the clinical outcomes of patients with fungal PJIs treated with two-stage exchange knee arthroplasty combined with prolonged antifungal therapy.

Methods

We reviewed our institutional joint arthroplasty database and identified 41 patients diagnosed with fungal PJIs and treated with two-stage exchange arthroplasty after primary total knee arthroplasty (TKA) between January 2001 and December 2020, and compared them with those who had non-fungal PJIs during the same period. After propensity score matching based on age, sex, BMI, American Society of Anesthesiologists grade, and Charlson Comorbidity Index, 40 patients in each group were successfully matched. The surgical and antimicrobial treatment, patient demographic and clinical characteristics, recurrent infections, survival rates, and relevant risk factors that affected joint survivorship were analyzed. We defined treatment success as a well-functioning arthroplasty without any signs of a PJI, and without antimicrobial suppression, at a minimum follow-up of two years from the time of reimplantation.

Results

The fungal PJI group demonstrated a significantly worse treatment success rate at the final follow-up than the non-fungal PJI group (65.0% (26/40) vs 85.0% (34/40); p < 0.001). The mean prosthesis-free interval was longer in the fungal PJI group than in the non-fungal PJI group (6.7 weeks (SD 5.8) vs 4.1 weeks (SD 2.5); p = 0.020). The rate of survivorship free from reinfection was worse in the fungal PJI group (83.4% (95% confidence interval (CI) 64.1 to 92.9) at one year and 76.4% (95% CI 52.4 to 89.4) at two years) than in the non-fungal PJI group (97.4% (95% CI 82.7 to 99.6) at one year and 90.3% (95% CI 72.2 to 96.9) at two years), but the differences were not significant (p = 0.270). Cox proportional hazard regression analysis identified the duration of the prosthesis-free interval as a potential risk factor for failure (hazard ratio 1.128 (95% CI 1.003 to 1.268); p = 0.043).

Conclusion

Fungal PJIs had a lower treatment success rate than non-fungal PJIs despite two-stage revision arthroplasty and appropriate antifungal treatment. Our findings highlight the need for further developments in treating fungal PJIs.

Clinical epidemiology and case fatality due to antimicrobial resistance in Germany: a systematic review and meta-analysis, 1 January 2010 to 31 December 2021

BackgroundAntimicrobial resistance (AMR) is of public health concern worldwide.AimWe aimed to summarise the German AMR situation for clinicians and microbiologists.MethodsWe conducted a systematic review and meta-analysis of 60 published studies and data from the German Antibiotic-Resistance-Surveillance (ARS). Primary outcomes were AMR proportions in bacterial isolates from infected patients in Germany (2016-2021) and the case fatality rates (2010-2021). Random and fixed (common) effect models were used to calculate pooled proportions and pooled case fatality odds ratios, respectively.ResultsThe pooled proportion of meticillin resistance in Staphylococcus aureus infections (MRSA) was 7.9% with a declining trend between 2014 and 2020 (odds ratio (OR) = 0.89; 95% CI: 0.886-0.891; p < 0.0001), while vancomycin resistance in Enterococcus faecium (VRE) bloodstream infections increased (OR = 1.18; (95% CI: 1.16-1.21); p < 0.0001) with a pooled proportion of 34.9%. Case fatality rates for MRSA and VRE were higher than for their susceptible strains (OR = 2.29; 95% CI: 1.91-2.75 and 1.69; 95% CI: 1.22-2.33, respectively). Carbapenem resistance in Gram-negative pathogens (Klebsiella pneumoniae, Acinetobacter baumannii, Enterobacter spp. and Escherichia coli) was low to moderate (< 9%), but resistance against third-generation cephalosporins and fluoroquinolones was moderate to high (5-25%). Pseudomonas aeruginosa exhibited high resistance against carbapenems (17.0%; 95% CI: 11.9-22.8), third-generation cephalosporins (10.1%; 95% CI: 6.6-14.2) and fluoroquinolones (24.9%; 95% CI: 19.3-30.9). Statistical heterogeneity was high (I2 > 70%) across studies reporting resistance proportions.ConclusionContinuous efforts in AMR surveillance and infection prevention and control as well as antibiotic stewardship are needed to limit the spread of AMR in Germany.

Comparison of the BioFire Joint Infection Panel to 16S Ribosomal RNA Gene-Based Targeted Metagenomic Sequencing for Testing Synovial Fluid from Patients with Knee Arthroplasty Failure

The diagnosis of periprosthetic joint infection (PJI) is challenging, often requiring multiple clinical specimens and diagnostic techniques, some with prolonged result turnaround times. Here, the diagnostic performance of the Investigational Use Only (IUO) BioFire Joint Infection (JI) Panel was compared to 16S rRNA gene-based targeted metagenomic sequencing (tMGS) applied to synovial fluid for PJI diagnosis. Sixty synovial fluid samples from knee arthroplasty failure archived at -80°C were tested. Infectious Diseases Society of America (IDSA) diagnostic criteria were used to classify PJI. For culture-positive PJI with pathogens targeted by the JI panel, JI panel sensitivity was 91% (21/23; 95% confidence interval [CI], 73 to 98%), and tMGS sensitivity was 96% (23/24; 95% CI, 80 to 99%) (P = 0.56). Overall sensitivities of the JI panel and tMGS for PJI diagnosis were 56% (24/43; 95% CI, 41 to 70%) and 93% (41/44; 95% CI, 82 to 98%), respectively (P < 0.001). JI panel and tMGS overall specificities were 100% (16/16; 95% CI, 81 to 100%) and 94% (15/16; 95% CI, 72 to 99%), respectively. While the clinical sensitivity of the JI panel was excellent for on-panel microorganisms, overall sensitivity for PJI diagnosis was low due to the absence of Staphylococcus epidermidis, a common causative pathogen of PJI, on the panel. A PJI diagnostic algorithm for the use of both molecular tests is proposed.

Assessment of antimicrobial mismatches in empirical treatment in early PJI after aseptic revision arthroplasty

Background

In early periprosthetic joint infection (PJI), 'debridement, antibiotics and implant retention' (DAIR) is a widely accepted form of treatment. Empirical antimicrobial treatment is started while culture results of tissue samples taken during debridement are pending.

Objectives

In this retrospective study we assessed the antimicrobial mismatch rate between empirical treatment and the susceptibility of the causative microorganisms of PJI after aseptic revision arthroplasty. We analysed risk factors for antimicrobial mismatches and the impact of mismatches on the outcome of PJI treatment.

Results

A total of 119 patients were included in the analysis. In 72% (86/119) of the cases there was an antimicrobial mismatch in empirical treatment. Most of the antimicrobial mismatches were caused by multidrug-resistant (MDR) Staphylococcus spp. (77%, 66/86). In multivariable analysis, polymicrobial PJI was significantly associated with antimicrobial mismatch (OR: 6.89; 95% CI: 2.38-19.53; P < 0.001), and antimicrobial mismatch was significantly associated with reduced success rate of PJI treatment (OR: 0.20; 95% CI: 0.05 ± 0.82; P = 0.026). There was no difference in successful outcome between PJI caused by Gram-negative bacilli (61%) and Gram-positive bacteria (69%, P = 0.516).

Conclusions

Mismatching empirical antimicrobial treatment after DAIR following aseptic revision arthroplasty was significantly associated with failure of PJI treatment. Polymicrobial PJI is a risk factor for antimicrobial mismatch of the empirical treatment of PJI. Antimicrobial mismatch and delay in targeted treatment should be integrated in the approach to optimize antibiotic treatment to improve clinical outcomes, while minimizing unintended side effects of antimicrobial use (antimicrobial stewardship).

International Survey of Practice for Prophylactic Systemic Antibiotic Therapy in Hip and Knee Arthroplasty

(1) Background: Prophylactic systemic antibiotics are acknowledged to be an important part of mitigating prosthetic joint infections. Controversy persists regarding optimal antibiotic regimes. We sought to evaluate current international antibiotics guidelines for total joint arthroplasty (TJA) of the hip and knee. (2) Methods: 42 arthroplasty societies across 6 continents were contacted and their published literature reviewed. (3) Results: 17 societies had guidelines; of which 11 recommended an antibiotic agent or antibiotic class (10—cephalosporin; 1—cloxacillin); 15 recommended antibiotic infusion within an hour of incision and 10 advised for post-operative doses (8—up to 24 h; 1—up to 36 h; 1—up to 48 h). (4) Conclusions: Prophylactic antibiotic guidelines for TJA are often absent or heterogenous in their advice.

Rates of Antimicrobial Resistance With Extended Oral Antibiotic Prophylaxis After Total Joint Arthroplasty

Background

There is increased interest and utilization of extended oral antibiotic prophylaxis (EOAP) following primary and revision total hip arthroplasties (THAs) and total knee arthroplasties (TKAs). The purpose of this study was to look for potential associations between EOAP and differential rates of antimicrobial resistance or epidemiology of organisms causing periprosthetic joint infection (PJI) following primary and aseptic revision THAs/TKAs.

Methods

Patients who developed PJI following a primary or aseptic revision TKA/THA at a single institution from 2009 to 2020 were retrospectively identified. Patients who received at least 7 days of EOAP following the surgery were noted. Rates of antimicrobial resistance were compared between standard antibiotic prophylaxis and EOAP cohorts using the Fisher's exact test.

Results

One hundred twenty-eight cultures were obtained from 119 patients with PJI. Fourty-four cases (37%) developed PJI after EOAP. Staphylococcus aureus was the most frequently isolated organism (30% of all cultures; 78% were methicillin-sensitive). Rates of antimicrobial resistance were similar between standard antibiotic prophylaxis and EOAP cohorts in all but 2 instances: Increased resistance to erythromycin and trimethoprim-sulfamethoxazole was observed in coagulase-negative Staphylococci isolates in the EOAP cohort (89% vs 21%, P < .01; 44% vs 0%, P = .02). An increased frequency of gram-negative organisms was observed in the EOAP group (22% vs 8%, P = .03).

Conclusions

Rates of antimicrobial resistance were not significantly different between EOAP and standard antibiotic prophylaxis cohorts except in coagulase-negative Staphylococci. The increased frequency of gram-negative infections was present in the EOAP cohort. Larger, multicenter studies are needed to better understand the impact of EOAP on antimicrobial resistance and PJI epidemiology.

Level of Evidence

Level III; retrospective cohort study.

Effectiveness of mechanical cleaning, antibiotics, and induction heating on eradication of Staphylococcus aureus in mature biofilms

Aims

Here we used a mature seven-day biofilm model of Staphylococcus aureus, exposed to antibiotics up to an additional seven days, to establish the effectiveness of either mechanical cleaning or antibiotics or non-contact induction heating, and which combinations could eradicate S. aureus in mature biofilms.

Methods

Mature biofilms of S. aureus (ATCC 29213) were grown on titanium alloy (Ti6Al4V) coupons for seven days and were subjected to the following treatments or their combinations: antibiotics, mechanical cleaning, or heat shock by induction heating of 60°C for one minute. Experiments were repeated at least five times.

Results

In the untreated biofilm, growth up to 1.8×10¹¹ colony-forming units (CFU)/cm² was observed. Treatment with ciprofloxacin, flucloxacillin, vancomycin, cefuroxime, and amoxicillin all with rifampicin gave 6.0 log, 6.1 log, 1.4 log, 4.8 log, and 3.6 log reduction in CFU/cm², respectively. Mechanical cleaning alone resulted in 4.9 log reduction and induction heating in 7.3 log reduction. There was an additional effect of ciprofloxacin, flucloxacillin, and induction heating when used in combinations. There was no additional effect for mechanical cleaning. No bacterial growth could be detected after induction heating followed by seven days of ciprofloxacin with rifampicin.

Conclusion

Mechanical cleaning, antibiotics, and non-contact induction heating reduced the bacterial load of mature S. aureus biofilms with approximately 5 log or more as a single treatment. The effect of mechanical cleaning on mature S. aureus biofilms was limited when used in combination with antibiotics and/or induction heating.

Cite this article: Bone Joint Res 2022;11(9):629–638.

Significant Difference in Antimicrobial Resistance of Coagulase Negative Periprosthetic Joint Infection in Septic Revision Total Knee Arthroplasty Between Two Major Orthopedic Centers

BACKGROUND

Antimicrobial resistance is recognized as a major public health threat. It occurs naturally; however, an excessive antibiotic use and misuse of antibiotics accelerate the process. Periprosthetic joint infections (PJI) are becoming harder to treat as the efficacy of antibiotics is becoming lower. The aim of this study was to compare the resistance of coagulase-negative staphylococci (CNS) to antibiotics identified after revision TKAs for PJI between two major orthopedic centers.

METHODS

A review of all revision TKAs, undertaken between 2006 and 2018 in two orthopedic centers, was performed, including all those meeting the consensus criteria for PJI, in which CNS were identified. There were no major differences in surgical approach and tissue sampling between both centers. Thirteen commonly used antibiotics were tested at both centers.

RESULTS

The 132 strains were analyzed for their resistance to 13 different antibiotics. Staphylococcus epidermidis was identified in 70.5% cultures, followed by Staphylococcus capitis in 8.3% cultures. The comparison of antibiotic resistance between two centers was statistically significant to penicillin (P = .001), oxacillin (P = .011), cefuroxime (P = .044), levofloxacin (P = .006), moxifloxacin (P = .008), tetracycline (P < .001), rifampicin (P < .001) and vancomycin (P < .001). The difference of resistance of CNS was not statistically significant to fosfomycin, clindamycin, teicoplanin, erythromycin and ampicillin.

CONCLUSIONS

The resistance of CNS to antibiotics differs significantly between two major orthopedic centers that are geographically fairly close. Monitoring of bacteriological analyses in each referral center should be continuously performed. Close monitoring is needed for more efficient antibiotic treatment of and prophylaxis against PJI.

Significant Difference in Antimicrobial Resistance of Bacteria in Septic Revision between Total Knee Arthroplasty and Total Hip Arthroplasty

Antimicrobial resistance (AMR) aggravates the already difficult treatment of periprosthetic joint infections (PJI). Due to many factors influencing AMR, the correct choice of antimicrobial management remains arguable. The primary purpose of this retrospective study was to identify and compare bacteria and their antibiotic resistance profile between septic revision total knee arthroplasty (TKA) and septic revision total hip arthroplasty (THA). A review of all revision TKAs and revision THAs, undertaken between 2007 and 2020 in a tertiary referral hospital, was performed. Included were cases meeting the consensus criteria for PJI, in which an organism has been identified. There were no major differences in tissue sampling between revision TKAs and revision THAs over time. A total of 228 bacterial strains, isolated after revision TKA and THA, were analysed for their resistance to 20 different antibiotics. There was a statistically significant higher occurrence of Gram-negative bacteria identified after revision THAs compared to TKA (p = 0.002). The comparison of antibiotic resistance between revision TKAs and revision THAs was statistically significant in 9 of 20 analysed antibiotics. This has implications for the choice of empirical antibiotic in revision surgery as well as prophylactic antibiotic in primary surgery, depending on the joint that is to be replaced.