ESSKA and EBJIS recommendations for the management of infections after anterior cruciate ligament reconstruction (ACL-R): prevention, surgical treatment and rehabilitation.

PURPOSE: Infection after anterior cruciate ligament reconstruction (ACL-R) is a rare but severe complication. Despite an increase in articles published on this topic over the last decade, solid data to optimized diagnostic and therapeutic measures are scarce. For this reason, the European Bone and Joint Infection Society (EBJIS) and the European Society for Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA) collaborated in order to develop recommendations for the diagnosis and management of infections after ACL-R. The aim of the workgroup was to perform a review of the literature and provide practical guidance to healthcare professionals involved in the management of infections after ACL-R. METHODS: An international workgroup was recruited to provide recommendations for predefined clinical dilemmas regarding the management of infections after ACL-R. MEDLINE, EMBASE, Cochrane Library and Scopus databases were searched for evidence to support the recommended answers to each dilemma. RESULTS: The recommendations were divided into two articles. The first covers etiology, prevention, diagnosis and antimicrobial treatment of septic arthritis following ACL-R and is primarily aimed at infectious disease specialists. This article includes the second part of the recommendations and covers prevention of infections after ACL-R, surgical treatment of septic arthritis following ACL-R and subsequent postoperative rehabilitation. It is aimed not only at orthopedic surgeons, but at all healthcare professionals dealing with patients suffering from infections after ACL-R. CONCLUSION: These recommendations guide clinicians in achieving timely and accurate diagnosis as well as providing optimal management, both of which are paramount to prevent loss of function and other devastating sequelae of infection in the knee joint. LEVEL OF EVIDENCE: V.

Preoperative synovial fluid culture poorly predicts the pathogen causing periprosthetic joint infection.

PURPOSE: We investigated the value of preoperative pathogen detection and evaluated its concordance with intraoperative cultures in patients with culture-positive periprosthetic joint infection (PJI). METHODS: Culture-positive PJI episodes with available preoperative (synovial fluid) and intraoperative cultures (periprosthetic tissue, synovial or sonication fluid) were analyzed. The pathogen detection rate in preoperative and intraoperative cultures was compared using Fisher's exact test and their concordance was calculated. RESULTS: Among 167 included PJI episodes, 150 were monomicrobial with coagulase-negative staphylococci (n = 55, 37%), S. aureus (n = 34, 23%), and streptococci (n = 21, 14%) being the most common pathogens. Seventeen episodes (10%) were polymicrobial infections. The pathogen(s) grew in preoperative culture in 110 and in intraoperative cultures in 153 episodes (66% vs. 92%, p < 0.001). The pathogen detection rate was lower in preoperative compared to intraoperative cultures for low-virulent pathogens (40% vs. 94%, p < 0.001), polymicrobial infections (59% vs. 100%, p = 0.007), and in delayed and late PJI (63% vs. 94%, and 66% vs. 91%, respectively, p < 0.001). Full concordance of preoperative and intraoperative cultures was found in 87 episodes (52%). The pathogen was detected solely preoperatively in 14 episodes (8%) and solely intraoperatively in 57 cases (34%); an additional pathogen was found in 3 episodes (2%) preoperatively and in 6 episodes (4%) intraoperatively. CONCLUSION: The concordance of preoperative and intraoperative cultures was poor (52%). The sole or an additional pathogen was found exclusively in intraoperative cultures in 38% of PJI episodes, hence preoperative synovial fluid cultures are considered unreliable for pathogen detection in PJI.

The value of conventional radiographs for diagnosing internal fixation-associated infection.

BACKGROUND: The aim of the study is to  assess the diagnostic value of preoperative conventional radiographs for diagnosing infection associated with internal fixation devices. METHODS: We prospectively collected data of patients undergoing removal of internal fixation devices for any reason. Infection was diagnosed in case of purulence, sinus tract, positive histopathology and/or positive peri-implant tissue or sonication fluid culture. In radiographs radiolucent lines, implant breakage or displacement, or periosteal reaction were assessed. White blood cell count (WBC) and serum C-reactive protein (CRP) were determined at admission. RESULTS: We included 421 surgeries in 380 patients (median age 53.6 years, range 11-98 years), mainly indicated for infection (24.9%), nonunion (20.0%) and symptomatic implants (13.5%). Radiologic signs of infection included radiolucent lines (11.4%); implant breakage (12.4%) or displacement (10.7%); and periosteal reaction (7.1%). Infection was confirmed in 116 cases (27.6%). Only radiolucent lines (OR = 1.86 [95%CI: 1.00-3.38]) and periosteal reaction (OR = 2.48 [95%CI: 1.17-5.26]) were associated with infection, with a low sensitivity (16.4 and 12.1%, respectively), and high specificity (90.5 and 94.8%, respectively). Preoperative WBC and CRP had a sensitivity of 23.0 and 35.3%, and specificity of 91.7 and 89.5%, respectively. CONCLUSIONS: Radiological signs suggestive of infection were uncommon. Radiolucency and periosteal reaction were associated with infection, though with low sensitivity.

Value of multiplex PCR for detection of antimicrobial resistance in samples retrieved from patients with orthopaedic infections.

BACKGROUND: The performance of multiplex PCR (mPCR) for detection of antimicrobial resistance from clinical isolates is unknown. We assessed the ability of mPCR to analyse resistance genes directly from clinical samples. Patients with orthopedic infections were prospectively included. Phenotypical and genotypical resistance was evaluated in clinical samples (synovial and sonication fluid) where identical pathogens were identified by culture and mPCR. RESULT: A total of 94 samples were analysed, including 60 sonication fluid and 34 synovial fluid samples. For coagulase-negative staphylococcus strains, mPCR detected resistance to oxacillin in 10 of 23 isolates (44%) and to rifampin in none of 6 isolates. For S. aureus isolates, detection rate of oxacillin and rifampin-resistance was 100% (2/2 and 1/1, respectively). Fluoroquinolone-resistance was confirmed by mPCR in all 3 isolates of Enterobacteriaceae, in enterococci resistance to aminoglycoside-high level was detected in 1 of 3 isolates (33%) and in streptococci resistance to macrolides/lincosamides in none of 2 isolates. The overall sensitivity for different pathogens and antimicrobials was 46% and specificity 95%, the median concordance was 80% (range, 57-100%). Full agreement was observed for oxacillin in S. aureus, vancomycin in enterococci, carbapenems/cephalosporins in Enterobacteriaceae and rifampin in Cutibacterium species. CONCLUSION: The overall sensitivity for detection of antimicrobial resistance by mPCR directly from clinical samples was low. False-negative mPCR results occurred mainly in coagulase-negative staphylococci, especially for oxacillin and rifampin. However, the specificity of mPCR was high and a positive result reliably predicted antimicrobial resistance. Including universal primers in the PCR test assay may improve the detection rate but requires additional sequencing step. TRIAL REGISTRATION: www.clinicaltrials.gov No. NCT02530229, registered at 21 August 2015 (retrospectively registered).

Outcome of spinal implant-associated infections treated with or without biofilm-active antibiotics: results from a 10-year cohort study.

PURPOSE: Biofilm-active antibiotics are suggested to improve the outcome of implant-associated infections; however, their role in infections after spinal instrumentation is unclear. Therefore, we evaluated the outcome of patients with spinal implant-associated infections treated with and without biofilm-active antibiotics. METHODS: The probability of infection-free survival was estimated for treatment of spinal implant-associated infections with and without biofilm-active antibiotics using the Kaplan-Meier method; Cox proportional-hazards regression model was used to identify factors associated with treatment failure. RESULTS: Among 93 included patients, early-onset infection was diagnosed in 61 (66%) and late-onset in 32 infections (34%). Thirty patients (32%) were treated with biofilm-active antibiotic therapy and 63 (68%) without it. The infection-free survival after a median follow-up of 53.7 months (range, 8 days-9.4 years) was 67% (95% confidence interval [CI], 55-82%) after 1 year and 58% (95% CI 43-71%) after 2 years. The infection-free survival after 1 and 2 years was 94% (95% CI 85-99%) and 84% (95% CI 71-93%) for patients treated with biofilm-active antibiotics, respectively, and 57% (95% CI 39-80%) and 49% (95% CI 28-61%) for those treated without biofilm-active antibiotics, respectively (p = 0.009). Treatment with biofilm-active antibiotics (hazard ratio [HR], 0.23, 95% CI 0.07-0.77), infection with Staphylococcus auras (HR, 2.19, 95% CI 1.04-4.62) and polymicrobial infection (HR, 2.44, 95% CI 1.09-6.04) were significantly associated with treatment outcome. Severe pain was observed more often in patients without biofilm-active antibiotic therapy (49% vs. 18%, p = 0.027). CONCLUSION: Treatment with biofilm-active antibiotics was associated with better treatment outcome and less postoperative pain intensity.

Thermogenic diagnosis of periprosthetic joint infection by microcalorimetry of synovial fluid.

BACKGROUND: Synovial fluid culture is the standard investigation for the preoperative diagnosis of periprosthetic joint infection (PJI). However, the culture has limited sensitivity and requires several days until result. We evaluated the value of isothermal microcalorimetry for real-time diagnosis of PJI based on heat produced by microbial growth in synovial fluid. METHODS: Patients undergoing aspiration of prosthetic hip or knee joint before revision surgery were prospectively included between 2014 and 2015. The performance of microcalorimetry was compared to synovial fluid culture using McNemar's chi-squared test. Pearson's correlation coefficient was calculated for synovial fluid leukocyte count and microcalorimetric heat. RESULTS: Of 107 included patients (58 knee and 49 hip prosthesis), PJI was diagnosed in 46 patients (43%) and aseptic failure in 61 patients (57%) according to institutional criteria. In 26 PJI cases (56%) the pathogen grew in synovial fluid and intra-operative cultures. The sensitivity of synovial fluid culture and microcalorimetry was both 39% and the results were concordant in 98 patients (92%). In patients with PJI, microcalorimetry missed 4 pathogens which grew in synovial fluid culture, whereas culture missed 4 pathogens detected by microcalorimetry. A linear correlation (r = 0.366) was found between leukocyte count and microcalorimetric heat in synovial fluid (p < 0.001). The median time to positivity of microcalorimetry was 9 h (range, 1-64 h) vs. 3 days for cultures (range, 1-14 days). CONCLUSION: Microcalorimetry of synovial fluid allows thermogenic diagnosis of periprosthetic joint infection in synovial fluid. The diagnostic performance of synovial fluid microcalorimetry is comparable to culture and delivers results considerably faster. TRIAL REGISTRATION: This prospective study was registered on August 21, 2015 with the public clinical trial identification NCT02530229.

Synovial Fluid d-Lactate-A Novel Pathogen-Specific Biomarker for the Diagnosis of Periprosthetic Joint Infection.

BACKGROUND: Synovial fluid d-lactate may be useful for diagnosing periprosthetic joint infection (PJI) as this biomarker is exclusively produced by bacteria. We evaluated the performance of synovial fluid d-lactate using 2 definition criteria and determined its optimal cutoff value for diagnosing PJI. METHODS: Consecutive patients undergoing joint aspiration before prosthesis revision were prospectively included. Synovial fluid was collected for culture, leukocyte count, and d-lactate concentration (by spectrophotometry). Youden's J statistic was used for determining optimal d-lactate cutoff value on the receiver operating characteristic curve by maximizing sensitivity and specificity. RESULTS: A total of 224 patients were included. Using Musculoskeletal Infection Society criteria, 71 patients (32%) were diagnosed with PJI and 153 (68%) with aseptic failure (AF), whereas using institutional criteria, 92 patients (41%) were diagnosed with PJI and 132 (59%) with AF. The optimal cutoff of synovial fluid d-lactate to differentiate PJI from AF was 1.3 mmol/L, independent of the used definition criteria. Synovial fluid d-lactate had a sensitivity of 94.3% (95% confidence interval [95% CI], 86.2-98.4) and specificity of 78.4% (95% CI, 66.8-81.2) using Musculoskeletal Infection Society criteria, whereas its sensitivity was 92.4% (95% CI, 84.9-96.9) and specificity 88.6% (95% CI, 81.9-93.5) using institutional criteria. The concentration of d-lactate was higher in infections caused by Staphylococcus aureus (P < .001) and streptococci (P = .016) than by coagulase-negative staphylococci or in culture-negative PJI. CONCLUSION: The synovial fluid d-lactate showed high sensitivity (>90%) for diagnosis of PJI using both definition criteria and correlated with the pathogen virulence. The high sensitivity makes this biomarker useful as a point-of-care screening test for PJI. LEVEL OF EVIDENCE: Diagnostic level I.

Correction to: Twenty common errors in the diagnosis and treatment of periprosthetic joint infection.

The article "Twenty common errors in the diagnosis and treatment of periprosthetic joint infection", written by Cheng Li, Nora Renz, Andrej Trampuz and Cristina Ojeda-Thies, was originally published electronically on the publisher's internet portal (currently SpringerLink) on October 2019 without open access.

Twenty common errors in the diagnosis and treatment of periprosthetic joint infection.

BACKGROUND: Misconceptions and errors in the management of periprosthetic joint infection (PJI) can compromise the treatment success. The goal of this paper is to systematically describe twenty common mistakes in the diagnosis and management of PJI, to help surgeons avoid these pitfalls. MATERIALS AND METHODS: Common diagnostic and treatment errors are described, analyzed and interpreted. RESULTS: Diagnostic errors include the use of serum inflammatory biomarkers (such as C-reactive protein) to rule out PJI, incomplete evaluation of joint aspirate, and suboptimal microbiological procedures (such as using swabs or collection of insufficient number of periprosthetic samples). Further errors are missing possible sources of distant infection in hematogenous PJI or overreliance on suboptimal diagnostic criteria which can hinder or delay the diagnosis of PJI or mislabel infections as aseptic failure. Insufficient surgical treatment or inadequate antibiotic treatment are further reasons for treatment failure and emergence of antimicrobial resistance. Finally, wrong surgical indication, both underdebridement and overdebridement or failure to individualize treatment can jeopardize surgical results. CONCLUSION: Multidisciplinary teamwork with infectious disease specialists and microbiologists in collaboration with orthopedic surgeons have a synergistic effect on the management of PJI. An awareness of the possible pitfalls can improve diagnosis and treatment results.

Enterococcal periprosthetic joint infection: clinical and microbiological findings from an 8-year retrospective cohort study.

BACKGROUND: Treatment of enterococcal periprosthetic joint infections (PJI) is challenging due to non-standardized management strategies and lack of biofilm-active antibiotics. The optimal surgical and antimicrobial therapy are unknown. Therefore, we evaluated characteristics and outcome of enterococcal PJI. METHODS: Consecutive patients with enterococcal PJI from two specialized orthopedic institutions were retrospectively analyzed. Both institutions are following the same diagnostic and treatment concepts. The probability of relapse-free survival was estimated using Kaplan-Meier survival curves and compared by log-rank test. Treatment success was defined by absence of relapse or persistence of PJI due to enterococci or death related to enterococcal PJI. Clinical success was defined by the infection-free status, no subsequent surgical intervention for persistent or perioperative infection after re-implantation and no PJI-related death within 3 months. RESULTS: Included were 75 enterococcal PJI episodes, involving 41 hip, 30 knee, 2 elbow and 2 shoulder prostheses. PJI occurred postoperatively in 61 episodes (81%), hematogenously in 13 (17%) and by contiguous spread in one. E. faecalis grew in 64 episodes, E. faecium in 10 and E. casseliflavus in one episode(s). Additional microorganism(s) were isolated in 38 patients (51%). Enterococci were susceptible to vancomycin in 73 of 75 isolates (97%), to daptomycin in all 75 isolates, and to fosfomycin in 21 of 22 isolates (96%). The outcome data was available for 66 patients (88%). The treatment success after 3 years was 83.7% (95% confidence interval [CI]; 76.1-96.7%) and the clinical success was 67.5% (95% CI; 57.3-80.8%). In 11 patients (17%), a new PJI episode caused by a different pathogen occurred. All failures occurred within 3 years after surgery. CONCLUSION: About half of enterococcal PJI were polymicrobial infections. The treatment success was high (84%). All treatment failures occurred within the first 3 years after revision surgery. Interestingly, 17% of patients experienced a new PJI caused by another pathogen at a later stage. TRIAL REGISTRATION: The study was retrospectively registered with the public clinical trial identification NCT0253022 at https://www.clinicaltrials.gov on 15 July 2015.

Clinically Asymptomatic Patients Show a High Bacterial Colonization Rate of Osteosynthetic Implants Around the Knee but Not the Hip.

BACKGROUND: Patients with osteosynthetic implants around the hip and knee show higher infection rates after joint arthroplasty. Our aim was to evaluate the bacterial colonization of any osteosynthetic implants around the hip and knee in patients without clinical signs of infection. METHODS: Consecutive patients with osteosynthetic implant removal because of related soft tissue irritations or before elective total joint arthroplasty of the hip and knee were prospectively included. Patients with signs of infection were excluded. Based on sonication fluid cultures, implants were classified according to microbial growth as negative (no growth), contaminated (nonsignificant growth), or colonized (significant growth). RESULTS: Sonication cultures were positive in 54 of 203 implants (27%), including 8 of 34 (24%) after orthopedic and 46 of 169 (27%) after traumatological surgery. Of 203 sonication cultures, 22 (11%) grew significant bacterial counts. Most common microorganisms were coagulase-negative staphylococci (46%). Implants around the knee showed a significantly higher rate of positive sonication cultures compared with those around the hip (14% vs 2%, P = .017). CONCLUSIONS: We detected high bacterial implant colonization rates regardless of the initial type of surgery. Predominant pathogens were staphylococci, the most common causative agents of periprosthetic joint infections. Positive sonication results do not necessarily lead to postoperative surgical complications and thus do not equal infection. It remains unclear if patients with evidence of bacterial implant colonization show a higher risk of periprosthetic joint infection after adjacent subsequent total joint arthroplasty. Nevertheless, surgeons should be aware of a significantly higher colonization rate of implants around the knee and take this into consideration when total knee arthroplasty is scheduled in patients with osteosynthetic devices.

The worst-case scenario: treatment of periprosthetic femoral fracture with coexistent periprosthetic infection-a prospective and consecutive clinical study.

BACKGROUND: The simultaneous occurrence of periprosthetic fracture (PPF) and periprosthetic joint infection (PJI) is among the most devastating complications in arthroplasty and carries the risk of limb loss. For the first time, this study will describe the characteristics, treatment concepts, and outcomes of this complication. METHODS: Patients were consecutively included who were treated at our specialized interdisciplinary department between 2015 and 2016 with a PJI and an additional PPF of the hip. The treatment algorithm followed a three-step procedure: the complete removal of any foreign material (step 1), fracture stabilization by plate, intramedullary rod osteosynthesis or cerclages using an additional spacer (step 2), and reimplantation of a new prosthesis (step 3). RESULTS: Overall, eight cases [four male, four female, mean age 77 years (55-91)] were included. The mean follow-up was 34 ± 8 months. The fractures included one PPF Vancouver B1, three B2/3, and four type C. Most frequent microbes were CNS (Coagulase-negative staphylococci) (n = 4), Cutibacterium (n = 2) and Staphylococcus aureus (n = 2). Mixed infections (≥ 2 microorganisms) occurred in five cases. The time between explanation and reimplantation was 42 ± 34 (range 7-123) days. A re-infection took place in one, a re-revision in four cases, and in five cases fracture healing was noticed. In all eight cases, freedom from the infection and limb preservation could be achieved. CONCLUSION: PPF in the case of a PJI is a devastating situation and a huge challenge. Extremity preservation should be the primary goal. The described procedure offers a possible solution.

Is the Enzyme-linked Immunosorbent Assay More Accurate Than the Lateral Flow Alpha Defensin Test for Diagnosing Periprosthetic Joint Infection?

BACKGROUND: Alpha defensin was proposed as a new biomarker in synovial fluid for the diagnostic workup of failed joint prostheses. To our knowledge, no comparative study of the performance of the quantitative enzyme-linked immunosorbent assay (ELISA) and qualitative lateral flow alpha defensin test has been reported. QUESTIONS/PURPOSES: (1) Using the proposed European Bone and Joint Infection Society (EBJIS) criteria for defining periprosthetic joint infection (PJI), is there a difference in the diagnostic accuracy of quantitative ELISA and qualitative lateral flow alpha defensin tests? (2) Is there a difference in the performance of the two alpha defensin tests when using three definition classification systems (Musculoskeletal Infection Society [MSIS], Infectious Diseases Society of America [IDSA], and proposed EBJIS)? METHODS: In this retrospective study of samples collected earlier as part of a related longitudinal study, we included patients in whom aspiration of the prosthetic hip or knee was performed as routine investigation before every revision arthroplasty. Between October 2016 and April 2017, a total of 73 patients were eligible for inclusion. As a result of an insufficient fluid volume for analysis (< 5 mL), two patients were excluded. Among the 71 patients in the final analysis, 54 had a knee and 17 a hip arthroplasty. Using the proposed EBJIS criteria, PJI was diagnosed in 22 patients (31%) and aseptic failure in 49 (69%). The alpha defensin ELISA and lateral flow tests were performed in synovial fluid. Patients were classified as having PJI or aseptic failure using the MSIS, the IDSA, and the proposed EBJIS criteria. Sensitivity and specificity of ELISA and the lateral flow alpha defensin test were calculated. Based on receiver operating characteristic analysis, area under the curve values were compared. RESULTS: When measured against the proposed EBJIS criteria, the sensitivity of alpha defensin ELISA and the lateral flow test was low and not different from one another with the numbers available at 50% (95% confidence interval [CI], 31%-69%) and 46% (95% CI, 27%-65%; p = 0.857), respectively, whereas both methods showed high specificity (98% [95% CI, 88%-100%]; p = 1.000). For sensitivity, the highest values were seen when compared against the MSIS criteria (ELISA: 85% [95% CI, 56%-97%], lateral flow: 77% [95% CI]; p = 0.871), intermediate with IDSA criteria (ELISA: 73% [95% CI, 48%-89%], lateral flow: 67% [95% CI]; p = 0.867), and lowest with proposed EBJIS criteria (ELISA: 50% [95% CI, 31%-69%], lateral flow: 46% [95% CI]; p = 0.763). Specificity, however, was high regardless of the criteria used, where ELISA and lateral flow produced results that were not different (MSIS: 98% [95% CI, 90%-100%], IDSA: 98% [95% CI, 90%-100%], EBJIS: 98% [95% CI, 88%-100%]; p = 1.000). The area under the curve of alpha defensin ELISA and the lateral flow test was similar, regardless of the definition criteria used (EBJIS: p = 0.566; IDSA: p = 0.425; MSIS: p = 0.339). CONCLUSIONS: There is no difference between the quantitative and qualitative alpha defensin test for confirmation of PJI, irrespective of applied definition criteria. Having the advantage of providing results within 10 minutes without the need for a laboratory facility, the qualitative test may be of interest in the intraoperative setting, however, at a cost of higher test expense. LEVEL OF EVIDENCE: Level I, diagnostic study.

Antibiotic-induced fever in orthopaedic patients-a diagnostic challenge.

INTRODUCTION: Antibiotic-induced fever is a probably underestimated complication, which may be misdiagnosed as new infection. In this study, characteristics, diagnostic approach, and outcome of antibiotic-induced fever in patients treated for musculoskeletal infections are described. METHODS: We retrospectively reviewed all patients with antibiotic-induced fever after surgery treated at our institution from 2014 to 2017. Antibiotic-induced fever was diagnosed, if the following criteria were fulfilled: (i) central (ear) body temperature > 38.0 °C; (ii) intravenous antibiotics for > three days; (iii) exclusion of infectious or other non-infectious causes of fever; and (iv) defervescence after discontinuation of antibiotics. RESULTS: We included 11 patients (median age 51 years) treated for infection after fracture fixation (n = 5), periprosthetic joint infections (n = 3), infection after spinal instrumentation (n = 1), and soft tissue infection (n = 2). The suspected antibiotics inducing fever were beta-lactam antibiotics (n = 9), vancomycin (n = 3), daptomycin (n = 2), clindamycin, and meropenem (n = 1 each). Additional clinical findings were reduced general condition, generalized exanthema, and rigors, whereas five patients were asymptomatic apart from a fever. Leukopenia was observed in nine patients and increase of C-reactive protein value in ten patients. Fever occurred after a median of 20 days of antibiotic treatment and resolved after a median of one day after discontinuation of the suspected antibiotic. CONCLUSIONS: Antibiotics should be considered as the possible cause of fever in orthopaedic patients receiving antimicrobial treament whenever clinical signs of new or persisting infection are lacking. Important hints suggestive for antibiotic-induced fever are good general condition despite high temperature and progressive leukopenia. Discontinuation or change to another substance leads to prompt defervescence, preventing unnecessary diagnostic procedures and antibiotic treatment.

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

BACKGROUND: Periprosthetic joint infections (PJI) caused by pathogens, for which no biofilm-active antibiotics are available, are often referred to as difficult-to-treat (DTT). However, it is unclear whether the outcome of DTT PJI is worse than those of non-DTT PJI. We evaluated the outcome of DTT and non-DTT PJI in a prospective cohort treated with a two-stage exchange according to a standardized algorithm. METHODS: Patients with hip and knee PJI from 2013 to 2015 were prospectively included and followed up for ≥ 2 years. DTT PJI was defined as growth of microorganism(s) resistant to all available biofilm-active antibiotics. The Kaplan-Meier survival analysis was used to compare the probability of infection-free survival between DTT and non-DTT PJI and the 95% confidence interval (95% CI) was calculated. RESULTS: Among 163 PJI, 30 (18.4%) were classified as DTT and 133 (81.6%) as non-DTT. At a mean follow-up of 33 months (range 24-48 months), the overall treatment success was 82.8%. The infection-free survival rate at 2 years was 80% (95% CI 61-90%) for DTT PJI and 84% (95% CI 76-89%) for non-DTT PJI (p = 0.61). The following mean values were longer in DTT PJI than in non-DTT PJI: hospital stay (45 vs. 28 days; p < 0.001), prosthesis-free interval (89 vs. 58 days; p < 0.001) and duration of antimicrobial treatment (151 vs. 117 days; p = 0.003). CONCLUSIONS: The outcome of DTT and non-DTT PJI was similar (80-84%), however, at the cost of longer hospital stay, longer prosthesis-free interval and longer antimicrobial treatment. It remains unclear whether patients undergoing two-stage exchange with a long interval need biofilm-active antibiotics. Further studies need to evaluate the outcome in patients treated with biofilm-active antibiotics undergoing short vs. long interval.

Performance of automated multiplex PCR using sonication fluid for diagnosis of periprosthetic joint infection: a prospective cohort.

PURPOSE: Sonication of explanted prostheses improved the microbiological diagnosis of periprosthetic joint infections (PJI). We evaluated the performance of automated multiplex polymerase chain reaction (PCR) using sonication fluid for the microbiological diagnosis of PJI. METHODS: In a prospective cohort using uniform definition criteria for PJI, explanted joint prostheses were investigated by sonication and the resulting sonication fluid was analyzed by culture and multiplex PCR. McNemar's Chi-squared test was used to compare the performance of diagnostic tests. RESULTS: Among 111 patients, PJI was diagnosed in 78 (70%) and aseptic failure in 33 (30%). For the diagnosis of PJI, the sensitivity and specificity of periprosthetic tissue culture was 51 and 100%, of sonication fluid culture 58 and 100%, and of sonication fluid PCR 51 and 94%, respectively. Among 70 microorganisms, periprosthetic tissue culture grew 52 (74%), sonication fluid culture grew 50 (71%) and sonication fluid PCR detected 37 pathogens (53%). If only organisms are considered, for which primers are included in the test panel, PCR detected 37 of 58 pathogens (64%). The sonication fluid PCR missed 19 pathogens (predominantly oral streptococci and anaerobes), whereas 7 additional microorganisms were detected only by PCR (including Cutibacterium spp. and coagulase-negative staphylococci). CONCLUSIONS: The performance of multiplex PCR using sonication fluid is comparable to culture of periprosthetic tissue or sonication fluid. The advantages of PCR are short processing time (< 5 h) and fully automated procedure. However, culture technique is still needed due to the low sensitivity and the need of comprehensive susceptibility testing. Modification of primers or inclusion of additional ones may improve the performance of PCR, especially of low-virulent organisms.

[Local antibiotic therapy]. / Lokale Antibiotikatherapie.

The treatment of superficial wound infections with local antibiotics is considered to be problematic as it is accompanied by an increased risk of resistance development and ineffectiveness in deeper regions. On the contrary, the local application of antibiotics is useful in arthroplasty and necessary if implants are utilized. The reason for this is the prevention of a rapid biofilm formation on foreign implants and a resulting infection may remain undiscovered until it becomes chronic. Apart from exogenous material, necrotic tissue (e. g. bone sequestra) provides suitable retreat areas for pathogens in the body. Because of the characteristics of bone and joint infections and an exceptional infection recurrence rate, a combined approach is required. Systemic antibiotic prophylaxis is able to reduce the number of pathogens acquired by perioperative contamination or hematogenic spread from another focus of infection; however, systemically applied antibiotics often fail to form an effective colonization barrier around the implant because their ability to penetrate the bone is relatively low. On the other hand, the high concentration of locally released antibiotics leads to an effective protection of the implant from bacteria in situ. Thus, for the treatment of implant-associated infections, systemic and local application of anti-infective agents is a reliable adjuvant measure that improves the therapeutic success. Polymethylmethacrylate (PMMA) bone cement is the most commonly used local drug carrier. Based on clinical and microbiological results, microbiologists and infectious disease experts together with the surgeon and pharmacist determine which anti-infective agents are indicated for systemic and local, PMMA cement-related application. Because there is no evident concept for the local application, unlike the recommendation for systemic use of anti-infective agents, this review article describes which aspects should be taken into account.

[Antibiotic strategies in trauma surgery : Treatment of implant-associated infections]. / Antiinfektiöse Strategien in der Unfallchirurgie : Therapie osteosyntheseassoziierter Infektionen.

Implant-associated infections represent a serious complication following fracture management. Due to biofilm formation, an optimized treatment strategy is required to treat these infections. Interdisciplinary cooperation between trauma surgeon, infectious diseases specialist and microbiologist enables the deployment of a concerted surgical and antibiotic treatment concept, which significantly influences treatment success. Fracture healing and chronic osteomyelitis prevention are the primary treatment goals. In general, the eradication of infection is possible with surgical debridement, change or removal of the implant and adequate antibiotic therapy. In some cases, suppressive therapy until consolidation of fracture and later removal of the implant is an option.

Successful treatment of periprosthetic joint infection caused by Granulicatella para-adiacens with prosthesis retention: a case report.

BACKGROUND: Granulicatella and Abiotrophia spp. are difficult to detect due to their complex nutritional requirements. Infections with these organisms are associated with high treatment failure rates. We report the first implant-associated infection caused by Granulicatella para-adiacens, which was cured with anti-microbial treatment consisting of anti-biofilm-active rifampin and debridement, exchange of mobile parts and retention of the prosthesis. CASE PRESENTATION: Patient with a history of left hip arthroplasty presented with acute onset of fever, pain and limited range of motion of the left hip. Arthrocentesis of the affected joint yielded purulent fluid and exchange of mobile parts of the prosthesis, but retention of fixed components was performed. Granulicatella para-adiacens grew from preoperative and intraoperative cultures, including sonication fluid of the removed implant. The transesophageal echocardiography showed a vegetation on the mitral valve; the orthopantogram demonstrated a periapical dental abscess. The patient was treated with intravenous penicillin G and gentamicin for 4 weeks, followed by levofloxacin and rifampin for additional 2 months. At discharge and at follow-up 1, 2 and 5 years later, the patient was noted to have a functional, pain-free, and radiologically stable hip prosthesis and the serum C-reactive protein was normal. CONCLUSIONS: Although considered a difficult-to-treat organism, we report a successful treatment of the Granulicatella hip prosthesis infection with prosthesis retention and a prolonged antibiofilm therapy including rifampin. The periapical dental abscess is considered the primary focus of hematogenously infected hip prosthesis, underlining the importance treatment of periodontitis prior to arthroplasty and of proper oral hygiene for prevention of hematogenous infection after arthroplasty.