[Acute postoperative infections after dual head arthroplasty in geriatric patients]

Acute periprosthetic joint infections (PJI) after dual head arthroplasty represent a major challenge with a 1-year mortality rate up to 50% in the mostly multimorbid geriatric patient collective. Due to the limited possibilities of preoperative patient optimization, infection rates of up to 9% have been reported, which is significantly higher than in elective arthroplasty. A therapeutic gold standard has not yet been established due to the heterogeneous study situation and the lack of prospective randomized studies. The most promising therapeutic option currently appears to be a single-stage stem replacement in combination with implantation of a cup component (conversion to total hip arthroplasty, infection eradication in up to 100%). An approach of débridement, antibiotics, implant retention (DAIR) alone shows significantly poorer success rates (16-82%). Surgical treatment should always be followed by antibiotic treatment with a total duration of 12 weeks. In addition to the established perioperative antibiotic prophylaxis, the use of antibiotic-loaded bone cement seems to be superior to cementless stem fixation in preventing PJI in dual head arthroplasty.

High treatment failure rate in haematogenous compared to non-haematogenous periprosthetic joint infection

Aims

A higher failure rate has been reported in haematogenous periprosthetic joint infection (PJI) compared to non-haematogenous PJI. The reason for this difference is unknown. We investigated the outcome of haematogenous and non-haematogenous PJI to analyze the risk factors for failure in both groups of patients.

Methods

Episodes of knee or hip PJI (defined by the European Bone and Joint Infection Society criteria) treated at our institution between January 2015 and October 2020 were included in a retrospective PJI cohort. Episodes with a follow-up of > one year were stratified by route of infection into haematogenous and non-haematogenous PJI. Probability of failure-free survival was estimated using the Kaplan-Meier method, and compared between groups using log-rank test. Univariate and multivariate analysis was applied to assess risk factors for failure.

Results

A total of 305 PJI episodes (174 hips, 131 knees) were allocated to the haematogenous (n = 146) or the non-haematogenous group (n = 159). Among monomicrobial infections, Staphylococcus aureus was the dominant pathogen in haematogenous PJI (76/140, 54%) and coagulase-negative staphylococci in non-haematogenous PJI (57/133, 43%). In both groups, multi-stage exchange (n = 55 (38%) in haematogenous and n = 73 (46%) in non-haematogenous PJI) and prosthesis retention (n = 70 (48%) in haematogenous and n = 48 (30%) in non-haematogenous PJI) were the most common surgical strategies. Median duration of antimicrobial treatment was 13.5 weeks (range, 0.5 to 218 weeks) and similar in both groups. After six years of follow-up, the probability of failure-free survival was significantly lower in haematogenous compared to non-haematogenous PJI (55% vs 74%; p = 0.021). Infection-related mortality was significantly higher in haematogenous than non-haematogenous PJI (7% vs 0% episodes; p = 0.001). Pathogenesis of failure was similar in both groups. Retention of the prosthesis was the only independent risk factor for failure in multivariate analysis in both groups.

Conclusion

Treatment failure was significantly higher in haematogenous compared to non-haematogenous PJI. Retention of the prosthesis was the only independent risk factor for failure in both groups.

Adverse Events Associated with Prolonged Antibiotic Therapy for Periprosthetic Joint Infections-A Prospective Study with a Special Focus on Rifampin

Periprosthetic Joint Infection (PJI) is a significant contributor to patient morbidity and mortality, and it can be addressed through a range of surgical interventions coupled with antibiotic therapies. Following surgical intervention(s), prolonged administration of oral antibiotics is recommended to cure PJI. There is a lack of reports on the adverse events (AEs) associated with oral antibiotics, particularly rifampin. This investigation sought to elucidate the occurrence of antibiotic-related AEs after an initial regimen of intravenous antibiotic administration, supplemented by an extended course of oral antibiotics. A prospective study of patients diagnosed with PJI of the hip, knee, or shoulder who underwent single-stage exchange arthroplasty (SSE) (10%), two-stage exchange arthroplasty (TSE) (81%), or debridement, antibiotics, and implant retention (DAIR) (6%) was performed. The primary outcome of interest was the detection of AEs, the secondary outcome the detection of a correlation between rifampin use and the incidence of AEs, and the tertiary outcome was whether oral antibiotic treatment needed to be adjusted or discontinued due to AEs. In addition, subjective tolerability was monitored throughout the study. A total of 336 events were identified for 73 out of 80 patients. The most frequently used antibiotics were rifampin and co-trimoxazole. Most AEs occurred in the gastrointestinal tract (46%). The most frequent AEs were nausea, inappetence, diarrhea, and skin rash. In 6% of cases, the AEs led to antibiotic discontinuation, and in 29% of cases, a dose adjustment of the oral therapy occurred, mainly with amoxicillin or co-trimoxazole. The majority of patients (55%) rated the subjective tolerability as good. In conclusion, AEs during antibiotic treatment for PJI are common. They mainly affect the gastrointestinal tract. Rifampin use might be a reason for the higher incidence of AEs compared to non-rifampin antibiotic treatment.

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.

Recommendations on diagnosis and antimicrobial treatment of infections after anterior cruciate ligament reconstruction (ACL-R) endorsed by ESSKA and EBJIS

Infection after anterior-cruciate ligament reconstruction (ACL-R) is a rare but devastating complication affecting predominantly young and sportive individuals. A timely and correct diagnosis as well as an optimized management are paramount to circumvent serious sequelae and compromise in life quality. These recommendations are primarily intended for use by infectious disease specialists and microbiologists, but also orthopedic surgeons and other healthcare professionals who care for patients with infections after ACL-R. They are based on evidence mainly originating from observational studies and opinions of experts in the field and cover the management of infections after ACL-R with a special focus on etiology, diagnosis, antimicrobial treatment and prevention. Comprehensive recommendations on prevention, surgical treatment and rehabilitation are presented separately in a document primarily addressing orthopedics professionals.

Guideline for management of septic arthritis in native joints (SANJO)

This clinical guideline is intended for use by orthopedic surgeons and physicians who care for patients with possible or documented septic arthritis of a native joint (SANJO). It includes evidence and opinion-based recommendations for the diagnosis and management of patients with SANJO.

Outcome and failure analysis of 132 episodes of haematogenous periprosthetic joint infections – a cohort study

Background

Outcome of haematogenous periprosthetic joint infection (PJI) and reasons for failure are largely unknown.

Methods

Outcome of consecutive patients with haematogenous PJI treated at our institution between 2010 and 2019 was evaluated. Failure was classified as persistence or relapse of infection or new infection. Failure-free survival was assessed using Kaplan-Meier analysis. Proportions between groups were compared with Fisher's exact test.

Results

132 haematogenous PJI episodes involving knee (n=76), hip (n=54), shoulder (n=1) or elbow (n=1) prostheses experienced by 110 patients were included. Median follow-up was 20.7 months (range, 0.2-89.9 months). Haematogenous PJI were caused by Staphylococcus aureus (n=49), Streptococcus spp. (n=36), Enterococcus faecalis (n=17), Enterobacterales (n=16), coagulase-negative staphylococci (n=9) and others (n=6). Debridement and implant retention were performed in 50 (38%), prosthesis exchange or removal in 79 (60%) and no surgery in 3 episodes (2%). Treatment failed in 42 episodes (32%), including 6 infection-related deaths. Among 36 non-fatal failures, 21 were caused by a new pathogen and 8 by the same pathogen, in 7 episodes no pathogen was isolated. Of all non-fatal failures, 19 (53%) PJI were of haematogenous origin. Identification of the primary focus, causative pathogen and CRIME80-Score did not influence treatment outcome, but failure rate was higher following prosthesis retention compared to multi-stage exchange.

Conclusions

Persistence-/relapse-free survival after treatment of haematogenous PJI was high (84%). New haematogenous PJI due to the same or a new pathogen occurred frequently, reducing the treatment success to 62% after 4 years of follow-up, suggesting an individual predisposition to haematogenous PJI. The outcome was similar for different pathogens, but worse in episodes treated with prosthesis retention compared to multi-stage exchange.

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.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04170-3.

Cognitive Effects of Montelukast: A Pharmaco-EEG Study

Montelukast is a well-established antiasthmatic drug with little side effects. It is a leukotriene receptor antagonist and recent research suggests cognitive benefits from its anti-inflammatory actions on the central nervous system. However, changes in brain activity were not directly shown so far in humans. This study aims to document changes in brain activity that are associated with cognitive improvement during treatment with Montelukast. We recorded EEG and conducted neuropsychological tests in 12 asthma-patients aged 38-73 years before and after 8 weeks of treatment with Montelukast. We found no significant changes on neuropsychological scales for memory, attention, and mood. In the EEG, we found decreased entropy at follow up during rest (p < 0.005). During episodic memory acquisition we found decreased entropy (p < 0.01) and acceleration of the background rhythm (p < 0.05). During visual attention performance, we detected an increase in gamma power (p < 0.005) and slowing of the background rhythm (p < 0.05). The study is limited by its small sample size, young age and absence of baseline cognitive impairment of the participants. Unspecific changes in brain activity were not accompanied by cognitive improvement. Future studies should examine elderly patients with cognitive impairment in a double-blind study with longer-term treatment by Montelukast.

Controversy about the Role of Rifampin in Biofilm Infections: Is It Justified?

Rifampin is a potent antibiotic against staphylococcal implant-associated infections. In the absence of implants, current data suggest against the use of rifampin combinations. In the past decades, abundant preclinical and clinical evidence has accumulated supporting its role in biofilm-related infections.In the present article, experimental data from animal models of foreign-body infections and clinical trials are reviewed. The risk for emergence of rifampin resistance and multiple drug interactions are emphasized. A recent randomized controlled trial (RCT) showing no beneficial effect of rifampin in patients with acute staphylococcal periprosthetic joint infection treated with prosthesis retention is critically reviewed and data interpreted. Given the existing strong evidence demonstrating the benefit of rifampin, the conduction of an adequately powered RCT with appropriate definitions and interventions would probably not comply with ethical standards.

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.

[Septic arthritis of the native joint and after ligamentoplasty : Diagnosis and treatment]

BACKGROUND

Septic arthritis is an acute emergency. It occurs more frequently in patients with pre-existing degenerative or chronic inflammatory joint diseases than in the general population. The causative microorganisms can be introduced in various ways.

DIAGNOSTICS

A rapid diagnosis is of great importance for the success of the therapy. In the clinical examination, the typical signs of inflammation are noticeable. The gold standard is the aspiration of synovial fluid and the subsequent laboratory and microbiological investigation.

THERAPY

A prerequisite for successful therapy is the early initiation of an antimicrobial pathogen-specific treatment and the surgical alleviation of the joint.

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.

Spinal implant-associated infections: a prospective multicentre cohort study

This study evaluated the clinical, laboratory, microbiological, radiological and treatment characteristics of patients with early-onset and late-onset spinal implant-associated infections. Patients diagnosed with spinal implant-associated infection between 2015-2019 were prospectively included and treated according to a standardised algorithm. Infections were classified as early-onset (≤6 weeks) and late-onset (>6 weeks). Among 250 patients, 152 (61%) had early-onset and 98 (39%) had late-onset infection. Local inflammatory signs was the most common manifestation in early-onset infections (84%), whereas late-onset infections presented mainly with persisting or increasing local pain (71%). Sonication fluid was more often positive than peri-implant tissue samples (90% vs. 79%; P = 0.016), particularly in late-onset infections (92% vs. 75%; P = 0.005). Predominant pathogens were coagulase-negative staphylococci, Staphylococcus aureus and Cutibacterium spp. Debridement and implant retention was the most common surgical approach in early-onset infections (85%), whereas partial or complete implant exchange was mainly performed in late-onset infections (62%). Of the 250 patients, 220 (88%) received biofilm-active antibiotics, and median treatment duration was 11.7 weeks. Moreover, 49 patients (20%) needed more than one revision for infection and six patients (2.4%) died during hospital stay. Concluding, most spinal implant-associated infections were acquired during surgery and presented within 6 weeks of surgery. Infections presented mainly with local inflammatory signs in early-onset and with persisting or increasing pain in late-onset infections. Sonication was the most sensitive microbiological method, particularly in late-onset infections. Debridement and implant retention was used in well-integrated implants without loosening, independent of the time of infection onset.

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.

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).

Sonication Improves Pathogen Detection in Ventriculoperitoneal Shunt-Associated Infections

BACKGROUND

Antimicrobial treatment of ventriculoperitoneal (VP) shunt infections is challenging when the causative pathogen is unknown.

OBJECTIVE

To evaluate the value of sonication of explanted shunt-devices to improve the microbiological detection rate.

METHODS

All consecutive patients undergoing revision surgery due to suspected VP-shunt infection from January 2015 to February 2017 were evaluated. Intraoperative tissue samples, wound swabs, and cerebrospinal fluid (CSF) were collected for microbiological examination. In a subgroup of patients, the removed implants were additionally sent for sonication.

RESULTS

A total of 35 patients were included with a mean age of 57.5 ± 18 yr, 21 were female (60%). In 13 patient's tissue samples, CSF and wound swabs were analyzed. In 22 patients, the explanted device was additionally sent for sonication. All 22 sonication cultures showed a positive microbiological result (100%), whereas with conventional microbiological methods, the causative microorganism was identified in 8 of 13 (61%; P = .018). Analyzed by method, all 22 sonication cultures (100%) were positive and 21 of 35 conventional microbiological analysis results (60%) detected the causative agent (P < .001.) In 18 patients (51%), antimicrobial treatment was started preoperatively. In those patients, the pathogen was detected in all 12 sonication cultures (100%), whereas conventional methods grew a pathogen in 3 of 6 patients (P = .005).

CONCLUSION

Sonication significantly increases the microbiological yield in VP-shunt infections, especially in patients receiving antibiotics prior to diagnostics and in infections caused by low-virulent organisms. The implementation of sonication into the clinical routine can substantially increase the rate of pathogen detection allowing targeted treatment.

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.

Complications of Resection Arthroplasty in Two-Stage Revision for the Treatment of Periprosthetic Hip Joint Infection

Little data is available regarding complications associated with resection arthroplasty in the treatment of hip periprosthetic joint infection (PJI). We assessed complications during and after two-stage revision using resection arthroplasty. In this retrospective study, 93 patients undergoing resection arthroplasty for hip PJI were included. Patients were assigned to a prosthesis-free interval of ≤10 weeks (group 1; 49 patients) or >10 weeks (group 2; 44 patients). The complication rates between groups were compared using the chi-squared test. The revision-free and infection-free survival was estimated using a Kaplan-Meier survival analysis. Seventy-one patients (76%) experienced at least one local complication (overall 146 complications). Common complications were blood loss during reimplantation (n = 25) or during explantation (n = 23), persistent infection (n = 16), leg length discrepancy (n = 13) and reinfection (n = 9). Patients in group 1 experienced less complications after reimplantation (p = 0.012). With increasing severity of acetabular bone defects, higher incidence of complications (p = 0.008), periprosthetic bone fractures (p = 0.05) and blood loss (p = 0.039) was observed. The infection-free survival rate at 24 months was 93.9% in group 1 and 85.9% in group 2. The indication for resection arthroplasty needs to be evaluated carefully, considering the high rate of complications and reduced mobility, particularly if longer prosthesis-free intervals are used.

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.

High frequency of low-virulent microorganisms detected by sonication of pedicle screws: a potential cause for implant failure

OBJECTIVE

Loosening of pedicle screws is a frequent complication after spinal surgery. Implant colonization with low-virulent microorganisms forming biofilms may cause implant loosening. However, the clinical evidence of this mechanism is lacking. Here, the authors evaluated the potential role of microbial colonization using sonication in patients with clinical pedicle screw loosening but without signs of infection.

METHODS

All consecutive patients undergoing hardware removal between January 2015 and December 2017, including patients with screw loosening but without clinical signs of infection, were evaluated. The removed hardware was investigated using sonication.

RESULTS

A total of 82 patients with a mean (± SD) patient age of 65 ± 13 years were eligible for evaluation. Of the 54 patients with screw loosening, 22 patients (40.7%) had a positive sonication result. None of the 28 patients without screw loosening who served as a control cohort showed a positive sonication result (p < 0.01). In total, 24 microorganisms were detected in those 22 patients. The most common isolated microorganisms were coagulase-negative staphylococci (62.5%) and Cutibacterium acnes (formerly known as Propionibacterium acnes) (25%). When comparing only the patients with screw loosening, the duration of the previous spine surgery was significantly longer in patients with a positive microbiological result (288 ± 147 minutes) than in those with a negative result (201 ± 103 minutes) (p = 0.02).

CONCLUSIONS

The low-virulent microorganisms frequently detected on pedicle screws by using sonication may be an important cause of implant loosening and failure. Longer surgical duration increases the likelihood of implant colonization with subsequent screw loosening. Sonication is a highly sensitive approach to detect biofilm-producing bacteria, and it needs to be integrated into the clinical routine for optimized treatment strategies.

Performance of synovial fluid D-lactate for the diagnosis of periprosthetic joint infection: A prospective observational study

OBJECTIVES

Synovial fluid leukocyte count is the current standard test for diagnosing periprosthetic joint infection (PJI). As D-lactate is almost exclusively produced by bacteria, it represents a useful biomarker for bacterial infection. We evaluated the performance of synovial fluid D-lactate for the diagnosis of PJI and compared it with the synovial fluid leukocyte count.

METHODS

Consecutive patients with joint aspiration of a prosthetic hip, knee or shoulder joint were prospectively included. PJI was diagnosed according to the working criteria of the European Bone and Joint Infection Society (EBJIS). The synovial fluid D-lactate was determined spectrophotometrically at 570 nm, synovial fluid leukocytes were counted by flow cytometry. The receiver operating characteristic (ROC) analysis was performed to assess the diagnostic performance of investigated parameters.

RESULTS

Of 148 patients, 44 (30%) were diagnosed with PJI and 104 (70%) with aseptic failure. For diagnosis of PJI, the sensitivity of synovial fluid D-lactate (at cut-off 1.263 mmol/l) was 86.4% [95% CI, 75.0-95.5%] and the specificity was 80.8% [95% CI, 73.1-88.5%]. The AUCs of D-lactate concentration and leukocyte count were 90.3% [95% CI 85.7-95.0%] and 91.0% [95% CI 85.1-96.8%], respectively (p = 0.8). Virulence of the pathogen did not influence the D-lactate concentration (p = 0.123). The synovial fluid erythrocyte concentration correlated with D-lactate in patients with aseptic failure (ρ = 0.339, p <0.01).

CONCLUSION

Synovial fluid D-lactate showed similar performance to the leukocyte count for diagnosis of PJI. Advantages of D-lactate test are requirement of low synovial fluid volume, short turnaround time and low cost.

A standardized interdisciplinary algorithm for the treatment of prosthetic joint infections

AIMS

In 2013, we introduced a specialized, centralized, and interdisciplinary team in our institution that applied a standardized diagnostic and treatment algorithm for the management of prosthetic joint infections (PJIs). The hypothesis for this study was that the outcome of treatment would be improved using this approach.

PATIENTS AND METHODS

In a retrospective analysis with a standard postoperative follow-up, 95 patients with a PJI of the hip and knee who were treated with a two-stage exchange between 2013 and 2017 formed the study group. A historical cohort of 86 patients treated between 2009 and 2011 not according to the standardized protocol served as a control group. The success of treatment was defined according to the Delphi criteria in a two-year follow-up.

RESULTS

Patients in the study group had a significantly higher Charlson Comorbidity Index (3.9 vs 3.1; p = 0.009) and rate of previous revisions for infection (52.6% vs 36%; p = 0.025), and tended to be older (69.0 vs 66.2 years; p = 0.075) with a broader polymicrobial spectrum (47.3% vs 33.7%; p = 0.062). The rate of recurrent infection (3.1% vs 10.4%; p = 0.048) and the mean time interval between the two stages of the procedure (66.6 vs 80.7 days; p < 0.001) were reduced significantly in the study group compared with the control group.

CONCLUSION

We were able to show that the outcome following the treatment of PJIs of the hip and knee is better when managed in a separate department with an interdisciplinary team using a standard algorithm.

Influence of retrieved hip- and knee-prosthesis biomaterials on microbial detection by sonication

Microorganisms' ability to adhere and form a biofilm differs among biomaterials; however, clinical data are conflicting. Microbial adherence and biofilm formation on different biomaterials of explanted joint prosthesis components were investigated. Consecutive patients with explanted joint prosthesis were prospectively included. The bacterial load dislodged from retrieved prosthetic components was evaluated qualitatively and quantitatively in sonication-fluid cultures. For comparison between groups, one-way ANOVA and Wilcoxon signed-rank test were used. A total of 112 components originating from 58 knee and 54 hip prostheses were retrieved from 40 patients. Components were made of titanium alloy in 42 cases, cobalt-chromium alloy in 38 and polyethylene in 32. Bacteria in sonication-fluid cultures grew in all polyethylene components (100 %), followed by titanium alloy (79 %) and cobalt-chromium components (71 %). Larger bacterial counts were found on polyethylene than on titanium (p < 0.013) or cobalt-chromium alloy (p = 0.028). Coagulase-negative Staphylococcus aureus and Streptococcus species were most commonly isolated. In conclusion, polyethylene showed larger biofilm burden than metal alloys, indicating their higher microbial adhesion affinity in vivo. Sonication of polyethylene liners, rather than the whole prosthesis, was sufficient for diagnosis of prosthetic joint infection. Moreover, bacterial counts were larger after sonication of polyethylene liners than of metal alloys, suggesting intrinsic differences in the ability for biofilm formation on various biomaterials. Polyethylene liners allowed the diagnosis of prosthetic joint infections (PJIs) in all investigated cases, suggesting that sonication of polyethylene liners rather than of the complete prosthesis was sufficient for pathogen detection in PJIs.

Meta-analysis of sonicate fluid in blood culture bottles for diagnosing periprosthetic joint infection

Introduction: Periprosthetic joint infection (PJI) is the most serious complication after arthroplasty, and the diagnosis of PJI is still challenging with modern medical technology. To improve the diagnostic rate, combined diagnostic methods are gradually beginning to be used to diagnose PJI. Sonication is one accurate way to diagnose PJI, but there is minimal research regarding the diagnostic value of sonicate fluid (SF) in blood culture bottles (BCB). Therefore, we evaluated this combined diagnostic method by meta-analysis. Methods: We searched English publications in electronic databases regarding the use of sonicate fluid in blood culture bottles (SF-BCB) for diagnosing PJI, screened the literature according to inclusion criteria, assessed the quality of the selected literature, and collected information regarding SF-BCB. Results: This meta-analysis includes 4 studies that evaluated SF-BCB for the diagnosis of PJI. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic odds ratio (DOR) are 0.85 (95% Confidence interval [CI], 0.77 to 0.91), 0.86 (CI, 0.81 to 0.91), 5.34 (CI, 3.13 to 9.11), 0.16 (CI, 0.06 to 0.48) and 39.01 (CI, 9.04 to 168.35), respectively. The area under the curve (AUC) of the summary receiver operating characteristic (SROC) is 0.9186 (standard error, 0.0205). Conclusion: SF-BCB has great value for the microbiological diagnosis of PJ, especially for patients with prior antibiotic treatment.

Origin and characteristics of haematogenous periprosthetic joint infection

OBJECTIVES

Recognition of infectious origin of haematogenous periprosthetic joint infections (PJI) is crucial. We investigated the primary focus and characteristics of haematogenous PJI.

METHODS

Consecutive patients who presented with haematogenous PJI between 01/2010 and 01/2018 were retrospectively analysed. Haematogenous PJI was defined by diagnosis of infection ≥1 month after surgery, acute manifestation after a pain-free period and positive blood or prosthetic-site culture and/or evidence of distant infectious focus consistent with the pathogen. Fisher's exact, Student's t and Mann-Whitney U tests were used, as appropriate.

RESULTS

A total of 106 episodes of PJI were included, involving 59 knee, 45 hip, one shoulder and one elbow prostheses. The median time from last surgery until haematogenous PJI was 47 months (range, 1-417 months). The pathogen was identified in 105 episodes (99%), including Staphylococcus aureus (n = 43), streptococci (n = 32), enterococci (n = 13), Gram-negative bacteria (n = 9) and coagulase-negative staphylococci (n = 8). Gram-negative bacteria were significantly more often found in hip joints than in knee joints. Blood cultures grew the pathogen in 43 of 70 episodes (61%). The primary infectious focus was identified in 72 episodes (68%) and included infections of intravascular devices or heart valves (22 episodes), skin and soft tissue (16 episodes), the oral cavity (12 episodes), urogenital (12 episodes) or gastrointestinal tract (seven episodes) and other sites (three episodes).

CONCLUSIONS

In acute PJI manifesting after a pain-free period, the haematogenous infection route should be considered and the primary infectious focus should be actively searched for. The cardiovascular system, skin and soft tissue, oral cavity, urogenital and gastrointestinal tracts were common origins of haematogenous PJI.

Multiplex Polymerase Chain Reaction and Microcalorimetry in Synovial Fluid: Can Pathogen-based Detection Assays Improve the Diagnosis of Septic Arthritis?

OBJECTIVE

To prospectively evaluate automated multiplex PCR and isothermal microcalorimetry tests for rapid and accurate diagnosis of septic arthritis.

METHODS

Patients with acute arthritis were prospectively included from October 2014 to September 2015. In synovial fluid (SF), leukocyte count and differential, culture, PCR, and microcalorimetry were determined. Septic arthritis was diagnosed by positive SF culture or (1) local clinical signs and symptoms, (2) increased SF leukocyte count, and (3) exclusion of noninfectious causes of inflammatory arthropathy. The performance of individual tests was compared with McNemar's test.

RESULTS

Among 57 patients, 22 (39%) were diagnosed with septic arthritis. SF culture grew a pathogen in 10 patients (46%), PCR was positive in 5 (23%), and microcalorimetry in 10 (46%). Compared to SF culture, 49 concordant pairs were found for both methods (PCR and microcalorimetry; 86% agreement). In SF, PCR failed to detect Staphylococcus aureus (2 patients), Streptococcus pneumoniae (1 patient), Streptococcus dysgalactiae (1 patient), and Clostridium clostridioforme (1 patient). Microcalorimetry failed to detect S. dysgalactiae (1 patient), Streptococcus agalactiae (1 patient), and C. clostridioforme (1 patient). No statistical differences between the performance of SF culture, and PCR and microcalorimetry, respectively, were found. The processing time for PCR was 5 h and for microcalorimetry a median of 8.8 h (range, 2.3-64 h), whereas cultures required a median of 4.5 days (range, 3-14 days).

CONCLUSION

Performance of SF PCR was inferior while microcalorimetry was similar to culture but provided results considerably faster. [Clinical trial registration number (https://www.clinicaltrials.gov): NCT02530229].

Management of Periprosthetic Joint Infection

Periprosthetic joint infection (PJI) is a serious complication after arthroplasty, which is associated with pain, prolonged hospital stay, multiple surgeries, functional incapacitation, and even mortality. Using scientific and efficient management protocol including modern diagnosis and treatment of PJI and eradication of infection is possible in a high percentage of affected patients. In this article, we review the current knowledge in epidemiology, classification, pathogenesis, diagnosis and treatment of PJI.

Orthopedic implant-associated infections caused by Cutibacterium spp. - A remaining diagnostic challenge

Background

The definition criteria and clinical characteristics of implant-associated infection (IAI) caused by Cutibacterium (formerly Propionibacterium) spp. are poorly known. We analyzed microbiologically proven Cutibacterium orthopedic IAI in a prospective cohort.

Methods

Patients with periprosthetic joint infections (PJI) and fixation device–associated infections (FDAI) caused by Cutibacterium spp. were prospectively included. IAI was defined by significant growth of Cutibacterium spp. and presence of at least one non-microbiological criterion for infection. The McNemar’s chi-squared or binomial test was used to compare the performance of diagnostic tests.

Results

Of 121 patients with Cutibacterium IAI, 62 patients (51%) had PJI and 59 (49%) had FDAI. 109 infections (90%) were caused by C. acnes and 12 (10%) by C. avidum. The median time from implantation until diagnosis of infection was 15.7 months (interquartile range, 5–46.5 months). Clinical local signs were present in 30 patients (28%) and radiological implant loosening in 64 patients (63%). Culture sensitivity of sonication fluid was 84%, of peri-implant tissue 84% and of synovial or peri-implant fluid 56% after 14 days of incubation.

Conclusion

Cutibacterium IAI was diagnosed late in the disease course and presented with subtle signs. Prolonged culture incubation and implant sonication improved the poor performance of conventional microbiological tests. Due to lack of reliable diagnostic tests, Cutibacterium remains difficult to detect making the diagnosis challenging.

Current perspectives on diagnosis and management of sternal wound infections

Deep sternal wound infection (DSWI), also known as mediastinitis, is a serious and potentially fatal condition. The diagnosis and treatment of DSWI are challenging. In this current narrative review, the epidemiology, risk factors, diagnosis, and surgical and antimicrobial management of DSWI are discussed. Ideally, the management of DSWI requires early and sufficient surgical debridement and appropriate antibiotic therapy. When foreign material is present, biofilm-active antibiotic therapy is also needed. Because DSWI is often complex, the management requires the involvement of a multidisciplinary team consisting of cardiothoracic surgeons, plastic surgeons, intensivists, infectious disease specialists, and clinical microbiologists.

Alpha Defensin Lateral Flow Test for Diagnosis of Periprosthetic Joint Infection: Not a Screening but a Confirmatory Test

BACKGROUND

Determination of alpha defensin in synovial fluid has shown promising results for diagnosing periprosthetic joint infection (PJI). The purposes of our study were to assess the performance of alpha defensin lateral flow (ADLF) test for the diagnosis of acute and chronic PJI using 3 classification systems and to compare its performance with the synovial fluid leukocyte count.

METHODS

Patients in whom aspiration of a prosthetic hip or knee joint was performed before revision arthroplasty were prospectively included. In addition to standard diagnostic tests, the ADLF test was performed in synovial fluid. Patients were classified as having PJI or aseptic failure according to the definition criteria of the Musculoskeletal Infection Society (MSIS), the Infectious Diseases Society of America (IDSA), and the proposed criteria of the European Bone and Joint Infection Society (EBJIS). The performance of the ADLF test and the leukocyte count was compared using the McNemar chi-square test.

RESULTS

Of 212 included patients, 151 (71%) had a knee prosthesis and 61 (29%) had a hip prosthesis. PJI was diagnosed in 45 patients (21%) using the MSIS criteria, in 55 patients (26%) using the IDSA criteria and in 79 patients (37%) using the proposed EBJIS criteria. The sensitivity of the ADLF test was 84% (95% confidence interval [CI], 71% to 94%) with the MSIS criteria, 67% (95% CI, 53% to 79%) with the IDSA criteria, and 54% (95% CI, 43% to 66%) with the proposed EBJIS criteria. The ADLF test showed high specificity using all classification criteria (96% to 99%) and represented the most specific preoperative test for PJI, especially in the early postoperative period (91%; 95% CI, 59% to 100%). Using the proposed EBJIS definition criteria, the sensitivity of the leukocyte count was significantly higher than that of the ADLF test (86% [95% CI, 76% to 93%] compared with 54% [95% CI, 43% to 66%]; p < 0.001), particularly in chronic PJI (81% compared with 44%, respectively; p < 0.001).

CONCLUSIONS

The ADLF test was rapid and highly specific for diagnosing PJI (>95%). However, its sensitivity was limited (54% to 84%) and it should therefore not be used for screening, but rather as a confirmatory test for PJI.

LEVEL OF EVIDENCE

Diagnostic Level I. See Instructions for Authors for a complete description of levels of evidence.

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.

Value of PCR in sonication fluid for the diagnosis of orthopedic hardware-associated infections: Has the molecular era arrived?

INTRODUCTION

Bone healing disturbance following fracture fixation represents a continuing challenge. We evaluated a novel fully automated polymerase chain reaction (PCR) assay using sonication fluid from retrieved orthopedic hardware to diagnose infection.

PATIENTS AND METHODS

In this prospective diagnostic cohort study, explanted orthopedic hardware materials from consecutive patients were investigated by sonication and the resulting sonication fluid was analyzed by culture (standard procedure) and multiplex PCR (investigational procedure). Hardware-associated infection was defined as visible purulence, presence of a sinus tract, implant on view, inflammation in peri-implant tissue or positive culture. McNemar's chi-squared test was used to compare the performance of diagnostic tests. For the clinical performance all pathogens were considered, whereas for analytical performance only microorganisms were considered for which primers are included in the PCR assay.

RESULTS

Among 51 patients, hardware-associated infection was diagnosed in 38 cases (75%) and non-infectious causes in 13 patients (25%). The sensitivity for diagnosing infection was 66% for peri-implant tissue culture, 84% for sonication fluid culture, 71% (clinical performance) and 77% (analytical performance) for sonication fluid PCR, the specificity of all tests was >90%. The analytical sensitivity of PCR was higher for gram-negative bacilli (100%), coagulase-negative staphylococci (89%) and Staphylococcus aureus (75%) than for Cutibacterium (formerly Propionibacterium) acnes (57%), enterococci (50%) and Candida spp. (25%).

CONCLUSION

The performance of sonication fluid PCR for diagnosis of orthopedic hardware-associated infection was comparable to culture tests. The additional advantage of PCR was short processing time (<5 h) and fully automated procedure. With further improvement of the performance, PCR has the potential to complement conventional cultures.

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.

Diagnostik implantatassoziierter Infektionen und Stellenwert der Sonikation

Der Behandlungserfolg implantatassoziierter Infektionen ist in hohem Maße von einer angemessenen Diagnostik abhängig. Insbesondere „low-grade“-Infektionen präsentieren sich oft mit wenig ausgeprägten und unspezifischen klinischen Symptomen und erfordern deshalb eine optimierte diagnostische Aufarbeitung. Für die Diagnosestellung werden Anamnese, klinische Zeichen, Laborparameter, bildgebende Verfahren sowie histologische und mikrobiologische Untersuchungen herangezogen. Mikroorganismen bilden auf Implantatoberflächen einen Biofilm aus amorpher Polymermatrix, in der die Bakterien eingebettet sind. Dies erschwert den Nachweis der verursachenden Erreger mit konventionellen mikrobiologischen Methoden. Mittels Sonikation können Biofilme durch Ultraschallwellen von Oberflächen abgelöst und die resultierende Sonikationsflüssigkeit anschließend mikrobiologisch analysiert werden. Mit diesem Verfahren gelingt die Erregeridentifikation bei implantatassoziierten Infektionen deutlich häufiger und ermöglicht somit eine gezielte Antibiotikatherapie.

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.

Hematogenous vertebral osteomyelitis associated with intravascular device-associated infections - A retrospective cohort study

INTRODUCTION

Aim of the study was to investigate the clinical, microbiological, radiological, and treatment characteristics of hematogenous vertebral osteomyelitis originating from infected intravascular devices.

PATIENTS AND METHODS

Patients with secondary hematogenous vertebral osteomyelitis caused by an infected intravascular device were included in this retrospective cohort study. Patients with prior spinal surgery were excluded. Categorical variables were compared using χ² or Fisher's exact tests and continuous variables using the Mann-Whitney U test.

RESULTS

Sixty-seven patients with hematogenous vertebral osteomyelitis were included. Intravenous catheters were the source of infection in 45 patients (67%) and cardiovascular devices in 22 (33%). Fever was present in 21 patients (45%). The main pathogens were coagulase-negative staphylococci, isolated in 42 patients (63%), which grew from blood culture in 52 patients (87%), from vertebral tissue in 29 patients (56%) and from the explanted intravascular device in 18 patients (60%), where it was sampled. Infective endocarditis was diagnosed in 14 of 45 patients (31%), more common with cardiovascular devices than with intravascular catheters (56% versus 15%; P=0.008).

CONCLUSIONS

In patients with vertebral osteomyelitis, growth of coagulase-negative staphylococci in blood is highly suggestive for intravascular device-associated infection. Despite absence of systemic or local signs of inflammation at the site of the device, blood cultures should be collected and echocardiography performed in these patients.

[Management of periprosthetic infections of the knee]

Endoprosthetic replacement is one of the most successful operations in current medicine. As the implantation of knee prostheses increases, the number of periprosthetic infections is also rising. In case of painful or early loosening of the prosthesis an infection should be excluded by joint aspiration. Retention of the prosthesis with change of mobile parts is possible only in acute infections (< 4 weeks after surgery or duration of symptoms of <3 weeks in the case of hematogenous infection), if the prosthesis is stable, the soft tissue is intact, and no difficult-to-treat pathogens were found. In other cases a one- or two-stage prosthesis exchange should be performed. In a two-stage exchange, a short interval of 2-3 weeks is possible, if biofilm-active treatment is available. Rifampin should be used targeted (after isolation of the pathogen) and only in combination with another efficient antibiotic. In this article the current management concepts of periprosthetic infection of the knee are discussed.

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.

Right upper quadrant pain in a young female

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