Clinical Outcomes After Revision Hip Arthroplasty due to Prosthetic Joint Infection-A Single-Center Study of 369 Hips at a High-Volume Center With a Minimum of One Year Follow-Up.

BACKGROUND: Prosthetic joint infection (PJI) treatment decisions are traditionally based on treatment algorithms. There is, however, a lack of evidence to support the choice of these treatment algorithms. Therefore, we aimed to assess the one-year survival after PJI revision and compared different surgical strategies in a single-center setting. METHODS: Revisions of the hip due to PJI performed at our institution between January 2008 and September 2021 with at least one-year of follow-up were identified. In total, 134 debridement, antibiotics, and implant retentions (DAIRs), 114 one-stage revisions, and 121 two-stage revisions were performed. Infections were classified as early, acute hematogenous, and chronic. Survival was calculated using the Kaplan-Meier method and cumulative incidence function. Predictors of outcomes were examined with Fine-Gray regressions and Cox proportional hazards regressions. Subdistribution hazard ratios and hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated. RESULTS: At one-year follow-up, 26.6% (CI 22.2 to 31.2%) of the patients had undergone reoperation and 7.9% (CI 5.4 to 10.9%) had died. The risk for reoperation was highest after DAIR (36.6%, CI 28.5 to 44.7%) and lowest after one-stage revision (20.2%, CI 13.4 to 28%). Within the early infections, the one-stage revision almost halved the risk of reoperation (HR 0.51, CI 0.31 to 0.84) with no added mortality risk (HR 1.05, CI 0.5 to 2.2), when compared to DAIR. CONCLUSION: By utilizing 1-stage revision over DAIR in early infections, it might be possible to improve the prognosis by decreasing the risk of reoperation without increasing mortality. However, as the patient selection is undeniably difficult, more research is warranted.

Effect of non-cephalosporin antibiotic prophylaxis on the risk of periprosthetic joint infection after total joint replacement surgery: a retrospective study with a 1-year follow-up.

Background: Cephalosporins are recommended as first-line antibiotic prophylaxis in total joint replacement surgery. Studies have shown an increased risk for periprosthetic joint infection (PJI) when non-cephalosporin antibiotics have been used. This study examines the effect of non-cephalosporin antibiotic prophylaxis on the risk for PJI. Methods: Patients with a primary hip or knee replacement performed from 2012 to 2020 were identified (27 220 joint replacements). The primary outcome was the occurrence of a PJI in a one-year follow-up. The association between perioperative antibiotic prophylaxis and the outcome was examined using logistic regression analysis. Discussion: Cefuroxime was used as prophylaxis in 26,467 operations (97.2%), clindamycin in 654 (2.4%) and vancomycin in 72 (0.3%). The incidence of PJI was 0.86% (228/26,467) with cefuroxime and 0.80% (6/753) with other prophylactic antibiotics. There was no difference in the risk for PJI with different prophylactic antibiotics in the univariate (OR 1.06, 95% CI 0.47-2.39) or multivariable analysis (OR 1.02, 95% CI 0.45-2.30). Conclusion: Non-cephalosporin antibiotic prophylaxis in primary total joint replacement surgery was not associated with an increased risk for PJI.

Trends in Revision Knee Arthroplasty for Prosthetic Joint Infection: A Single-Center Study of 384 Knees at a High-Volume Center Between 2008 and 2021.

BACKGROUND: Prosthetic joint infection (PJI) is one of the most devastating complications after total knee arthroplasty (TKA), and comorbidities increase the risk. We examined whether a temporal change has occurred in the demographics, especially regarding comorbidities, of patients who have PJI and were treated at our institution over a 13-year study period. In addition, we assessed the surgical methods used and the microbiology of the PJIs. METHODS: Revisions (n = 384, 377 patients) due to PJI of the knee performed at our institution between 2008 and September 2021 were identified. All included PJIs fulfilled the 2013 International Consensus Meeting diagnostic criteria. The surgeries were categorized into one of the following categories: debridement, antibiotics, and retention (DAIR), 1-stage revision, and 2-stage revision. Infections were classified as early, acute hematogenous, and chronic. RESULTS: No changes in the median age of the patients nor comorbidity burden were observed during the study period. However, the proportion of 2-stage revisions decreased remarkably from 57.6% in 2008 to 2009 to 6.3% in 2020 to 2021. A DAIR was the most used treatment strategy, but the proportion of 1-stage revisions increased the most. In 2008 to 2009, 12.1% of the revisions were 1-stage, but in 2020 to 2021, the proportion was 43.8%. The most common pathogen was Staphylococcus aureus (27.8%). CONCLUSION: The comorbidity burden remained at the same level with no trends. A DAIR was the most used strategy, but the proportion of 1-stage revisions rose to almost the same level. The incidence of PJI varied between the years, but remained relatively low.

Trends in Revision Hip Arthroplasty for Prosthetic Joint Infection: A Single-Center Study of 423 Hips at a High-Volume Center Between 2008 and 2021.

BACKGROUND: Prosthetic joint infection (PJI) is one of the most devastating complications after total hip arthroplasty (THA), and comorbidities increase the risk. We examined whether there was a temporal change in the demographics, especially regarding comorbidities, of patients who have PJIs and were treated over a 13-year study period at a high-volume academic joint arthroplasty center. In addition, the surgical methods used and the microbiology of the PJIs were assessed. METHODS: Revisions (n = 423, 418 patients) due to PJI of the hip performed at our institution between 2008 and September 2021 were identified. All included PJIs fulfilled the 2013 International Consensus Meeting diagnostic criteria. The surgeries were categorized into one of the following categories: debridement, antibiotics, and implant retention, 1-stage revision, and 2-stage revision. Infections were classified as early, acute hematogenous, and chronic infections. RESULTS: There was no change in the median age of the patients, but the proportion of ASA-class 4 patients increased from 10.5% to 20%. The incidence of early infections increased from 0.11 per 100 primary THAs in 2008 to 1.09 in 2021. The incidence of 1-stage revisions increased the most, rising from 0.10 per 100 primary THAs in 2010 to 0.91 per 100 primary THAs in 2021. Furthermore, the proportion of infections caused by Staphylococcus aureus increased from 26.3% in 2008 to 2009 to 40% in 2020 to 2021. CONCLUSION: The comorbidity burden of PJI patients increased during the study period. This increase may present a treatment challenge, as comorbidities are known to have a negative effect on PJI treatment outcomes.

Surgical and patient-reported outcomes after total knee arthroplasty requiring soft tissue flap reconstruction - A 12-year experience from high-volume arthroplasty hospital.

BACKGROUND: This study investigates the outcomes of complex knee joint reconstructions performed by an orthoplastic surgery team at a tertiary referral hospital. METHODS: Retrospective review of all the total knee arthroplasty (TKA)/revision TKA (rTKA) procedures with soft tissue flap reconstruction performed between 2008 and 2019 was conducted. Patients were stratified into two groups according to the urgency of surgery: scheduled non-complicated (SNC) and emergent complicated (EC). The whole study cohort was also categorized into non-infected and infected groups. RESULTS: Of 20,184 TKAs operated, 58 patients required flap reconstruction (SNC group n = 27; EC group n = 31). The most common reconstruction was medial gastrocnemius flap (74%). Mean follow-up time was 31.9 months. Functional knee joint salvage was achieved in 96.3% the SNC group and in 80.6% the EC group patients (p = 0.07). Transfemoral amputation rates were 3.7% in the SNC group vs. 6.5% in the EC group (p = 0.36). Oxford Knee Score was 34.5 vs. 25.5 (p = 0.21), and range of motion was 100° vs. 93° (p = 0.37) in the SNC and EC groups, respectively. Superior functional knee joint salvage rates were achieved in the non-infected group compared to the infected group (97.1% vs. 75.0%, p = 0.004). However, the transfemoral amputation rate was nearly three-fold in the infected group (8.3% vs. 2.9%, p = 0.36). Estimated five-year survival with functional knee joint was higher in the non-infected group (p = 0.03). CONCLUSIONS: Both the SNC and EC groups had similar acceptable limb salvage rates, and functional and PROM outcomes. Infection reduces the probability of a functional knee joint after TKA and flap reconstruction.

Major Amputation Profoundly Increases Mortality in Patients With Diabetic Foot Infection.

Introduction: An acute diabetic foot infection (DFI) is a serious condition and a leading cause of hospitalization and major amputation in patients with diabetes. Aim of this study was to evaluate the long term survival and risk factors for death and amputation after the DFI requiring hospital treatment. Materials and Methods: A retrospective study included all adult patients hospitalized for DFI treatments during 2010-2014. Overall survival (OS) and amputation free survival (AFS) (without major amputation) was calculated. We performed a Cox regression analysis of several clinical parameters to evaluate the effects of clinical parameters on overall and amputation-free survival. Results: Total of 324 patients with mean age of 66.8 (SD 12.8) years were included. The one- and five-year OS after DFI 81.2% (95%CI 77.5-84.9%) and 49.7% (95%CI 44.8-54.6%), respectively. Major amputation, wound ischemia, older age, and a low glomerular filtration rate reduced the OS after DFI. After a major amputation, the one- and five-year OS was 41.7% (95%CI 13.9-69.5) and 8.3% (95%CI 0.0-24.0%), respectively. Wound ischemia, older age, and elevated C-reactive protein reduced AFS. In contrast, hypertensive medication use was identified as a protective factor. Conclusion: Mortality after a DFI remains high and is significantly increased after a major amputation. Findings highlight the importance of early wound and ischemia management for DFI prevention.

Pathogens Causing Diabetic Foot Infection and the Reliability of the Superficial Culture.

Background: Diabetic foot infection (DFI) is a severe complication of diabetes and a leading cause of hospitalization in the population with diabetes. Empirical intravenous antibiotic agents are initiated according to guidelines based on previously published data on typical pathogens. Therefore, regular evaluation of the pathogens in DFI and their resistance is important to validate current therapies. We evaluated the most current data on bacterial cultures in patients treated at our hospital for DFI and the resistance to the most common antibiotic agents, as well as the reliability of superficial cultures compared with deep tissue cultures. Patients and Methods: This retrospective study was performed at the University Hospital of Tampere and comprised 325 patients with 405 hospitalizations for DFI during the years 2010-2014. Results: The most frequent pathogens in superficial and deep samples were Staphylococcus aureus (36.9%), gram-negative bacilli (24.6%), and ß-hemolytic streptococci (BHS, 19.5%). Septicemia was caused most often by Staphylococcus aureus and BHS (34.6% each). The specificity of superficial culture was 91.8%-92.8% and sensitivity 66.7%-87.5%. Conclusions: This study indicates the need to cover Staphylococcus aureus, BHS, and gram-negative bacilli when treating DFI. The reliability of superficial culture was surprisingly good.

Periprosthetic Joint Infections as a Consequence of Bacteremia.

BACKGROUND: The risk for developing a periprosthetic joint infection (PJI) during bacteremia is unclear, except for Staphylococcus aureus bacteremia. The aim of this study was to examine the risk for developing a PJI during bacteremia and to identify possible risk factors leading to it. METHODS: Patients with a primary knee or hip joint replacement performed in a tertiary care hospital between September 2002 and December 2013 were identified (n = 14 378) and followed up until December 2014. Positive blood culture results during the study period and PJIs were recorded. PJIs associated with an episode of bacteremia were identified and confirmed from patient records. Potential risk factors for PJI among those with bacteremia were examined using univariate logistic regression. RESULTS: A total of 542 (3.8%) patients had at least 1 episode of bacteremia. Seven percent (47/643) of the bacteremias resulted in a PJI. Development of a PJI was most common for Staphylococcus aureus (21% of bacteremias led to a PJI) and beta-hemolytic streptococci (21%), whereas it was rare for gram-negative bacteria (1.3%). Having ≥2 bacteremias during the study period increased the risk for developing a PJI (odds ratio, 2.29; 95% confidence interval, 1.17-4.50). The risk for developing a PJI was highest for bacteremias occurring within a year of previous surgery. Chronic comorbidities did not affect the risk for PJI during bacteremia. CONCLUSIONS: The development of a PJI during bacteremia depends on the pathogen causing the bacteremia and the timing of bacteremia with respect to previous joint replacement surgery. However, significant patient-related risk factors for PJI during bacteremia could not be found.

Concordance between the old and new diagnostic criteria for periprosthetic joint infection.

PURPOSE: There is no uniform definition for periprosthetic joint infection (PJI). New diagnostic criteria were formulated in an international consensus meeting in 2013 and adopted by Centers for Disease Control (CDC) in 2016. The purpose of this study is to compare the new diagnostic criteria with the old CDC criteria from the year 1992. METHODS: Patients, who had been treated for PJI of hip or knee from 2002 to 2014, in a tertiary care hospital, were identified. Patient records were reviewed by a physician to identify PJI cases fulfilling the old or new CDC criteria and to record data concerning the diagnostic criteria. PJI frequencies were calculated for the two diagnostic criteria sets. Cross tables were formed to compare the concordance between the two sets of criteria in the whole material and in different clinical subgroups. RESULTS: Overall 405 cases fulfilling either or both sets of criteria for PJI were identified. 73 (18%) of the patients fulfilled only the old criteria, whereas only one (0.2%) fulfilled only the new criteria. Of the patients who did not fulfil the new criteria, in 39 (53%) the diagnosis was based solely on the clinician's opinion. CONCLUSIONS: The number of PJIs is notably lower when using the new, more objective, diagnostic criteria. A large portion of the cases diagnosed as infection by the treating clinician, did not fulfil the new diagnostic criteria.

Predictors of recurrent cellulitis in five years. Clinical risk factors and the role of PTX3 and CRP.

OBJECTIVES: To identify risk factors for recurrence of cellulitis, and to assess the predictive value of pentraxin 3 (PTX3) and C-reactive protein (CRP) measured at baseline. METHODS: A follow up study of 90 hospitalised patients with acute non-necrotising cellulitis was conducted. Clinical risk factors were assessed and PTX3 and CRP values were measured at baseline. Patients were contacted by phone at a median of 4.6 years after the baseline episode and the medical records were reviewed. RESULTS: Overall, 41% of the patients had a recurrence in the follow up. Of the patients with a history of a previous cellulitis in the baseline study 57% had a recurrence in five year follow up as compared to 26% of those without previous episodes (p = 0.003). In multivariate analysis, only the history of previous cellulitis was identified as an independent predicting factor for recurrence. The levels of pentraxin 3 (PTX3) or C-reactive protein (CRP) in the acute phase did not predict recurrence. CONCLUSIONS: Risk of recurrence is considerably higher after a recurrent episode than after the first episode. Clinical risk factors predisposing to the first cellulitis episode plausibly predispose also to recurrences.

Genetic susceptibility to non-necrotizing erysipelas/cellulitis.

BACKGROUND: Bacterial non-necrotizing erysipelas and cellulitis are often recurring, diffusely spreading infections of the skin and subcutaneous tissues caused most commonly by streptococci. Host genetic factors influence infection susceptibility but no extensive studies on the genetic determinants of human erysipelas exist. METHODS: We performed genome-wide linkage with the 10,000 variant Human Mapping Array (HMA10K) array on 52 Finnish families with multiple erysipelas cases followed by microsatellite fine mapping of suggestive linkage peaks. A scan with the HMA250K array was subsequently performed with a subset of cases and controls. RESULTS: Significant linkage was found at 9q34 (nonparametric multipoint linkage score (NPL(all)) 3.84, p=0.026), which is syntenic to a quantitative trait locus for susceptibility to group A streptococci infections on chromosome 2 in mouse. Sequencing of candidate genes in the 9q34 region did not conclusively associate any to erysipelas/cellulitis susceptibility. Suggestive linkage (NPL(all)>3.0) was found at three loci: 3q22-24, 21q22, and 22q13. A subsequent denser genome scan with the HMA250K array supported the 3q22 locus, in which several SNPs in the promoter of AGTR1 (Angiotensin II receptor type I) suggestively associated with erysipelas/cellulitis susceptibility. CONCLUSIONS: Specific host genetic factors may cause erysipelas/cellulitis susceptibility in humans.

Acquisition of complement factor H is important for pathogenesis of Streptococcus pyogenes infections: evidence from bacterial in vitro survival and human genetic association.

Streptococcus pyogenes (or group A streptococcus [GAS]) is a major human pathogen causing infections, such as tonsillitis, erysipelas, and sepsis. Several GAS strains bind host complement regulator factor H (CFH) via its domain 7 and, thereby, evade complement attack and C3b-mediated opsonophagocytosis. Importance of CFH binding for survival of GAS has been poorly studied because removal of CFH from plasma or blood causes vigorous complement activation, and specific inhibitors of the interaction have not been available. In this study, we found that activation of human complement by different GAS strains (n = 38) correlated negatively with binding of CFH via its domains 5-7. The importance of acquisition of host CFH for survival of GAS in vitro was studied next by blocking the binding with recombinant CFH5-7 lacking the regulatory domains 1-4. Using this fragment in full human blood resulted in death or radically reduced multiplication of all of the studied CFH-binding GAS strains. To study the importance of CFH binding in vivo (i.e., for pathogenesis of streptococcal infections), we used our recent finding that GAS binding to CFH is diminished in vitro by polymorphism 402H, which is also associated with age-related macular degeneration. We showed that allele 402H is suggested to be associated with protection from erysipelas (n = 278) and streptococcal tonsillitis (n = 209) compared with controls (n = 455) (p < 0.05). Taken together, the bacterial in vitro survival data and human genetic association revealed that binding of CFH is important for pathogenesis of GAS infections and suggested that inhibition of CFH binding can be a novel therapeutic approach in GAS infections.

Acute bacterial, nonnecrotizing cellulitis in Finland: microbiological findings.

BACKGROUND: Bacterial, nonnecrotizing cellulitis is a localized and often recurrent infection of the skin. The aim of this study was to identify the beta-hemolytic streptococci that cause acute nonnecrotizing cellulitis infection in Finland. METHODS: A case-control study of 90 patients hospitalized for acute cellulitis and 90 control subjects was conducted during the period of April 2004-March 2005. Bacterial swab samples were obtained from skin lesions or any abrasion or fissured toe web. Blood culture samples were taken for detection of bacteremia. The patients, their household members, and control subjects were assessed for pharyngeal carrier status. beta-Hemolytic streptococci and Staphylococcus aureus were isolated and identified, and group A and G streptococcal isolates were further analyzed by T serotyping and emm and pulsed-field gel electrophoresis typing. RESULTS: beta-Hemolytic streptococci were isolated from 26 (29%) of 90 patients, 2 isolates of which were blood-culture positive for group G streptococci, and 24 patients had culture-positive skin lesions. Group G Streptococcus (Streptococcus dysgalactiae subsp. equisimilis) was found most often and was isolated from 22% of patient samples of either skin lesions or blood, followed by group A Streptococcus, which was found in 7% of patients. Group G streptococci were also carried in the pharynx of 7% of patients and 13% of household members but was missing from control subjects. Several emm and pulsed-field gel electrophoresis types were present among the isolates. Six patients (7%) had recurrent infections during the study. In 2 patients, the group G streptococcal isolates recovered from skin lesions during 2 consecutive episodes had identical emm and pulsed-field gel electrophoresis types. CONCLUSIONS: Group G streptococci, instead of group A streptococci, predominated in bacterial cellulitis. No clear predominance of a specific emm type was seen. The recurrent nature of cellulitis became evident during this study.

An outbreak of Streptococcus equi subspecies zooepidemicus associated with consumption of fresh goat cheese.

BACKGROUND: Streptococcus equi subspecies zooepidemicus is a rare infection in humans associated with contact with horses or consumption of unpasteurized milk products. On October 23, 2003, the National Public Health Institute was alerted that within one week three persons had been admitted to Tampere University Central Hospital (TaYS) because of S. equi subsp. zooepidemicus septicaemia. All had consumed fresh goat cheese produced in a small-scale dairy located on a farm. We conducted an investigation to determine the source and the extent of the outbreak. METHODS: Cases were identified from the National Infectious Disease Register. Cases were persons with S. equi subsp. zooepidemicus isolated from a normally sterile site who had illness onset 15.9-31.10.2003. All cases were telephone interviewed by using a standard questionnaire and clinical information was extracted from patient charts. Environmental and food specimens included throat swabs from two persons working in the dairy, milk from goats and raw milk tank, cheeses made of unpasteurized milk, vaginal samples of goats, and borehole well water. The isolates were characterized by ribotyping and pulsed-field gel electrophoresis (PFGE). RESULTS: Seven persons met the case definition; six had septicaemia and one had purulent arthritis. Five were women; the median age was 70 years (range 54-93). None of the cases were immunocompromized and none died. Six cases were identified in TaYS, and one in another university hospital in southern Finland. All had eaten goat cheese produced on the implicated farm. S. equi subsp. zooepidemicus was isolated from throat swabs, fresh goat cheese, milk tank, and vaginal samples of one goat. All human and environmental strains were indistinguishable by ribotyping and PFGE. CONCLUSION: The outbreak was caused by goat cheese produced from unpasteurized milk. Outbreaks caused by S. equi subsp. zooepidemicus may not be detected if streptococcal strains are only typed to the group level. S. equi subsp. zooepidemicus may be a re-emerging disease if unpasteurized milk is increasingly used for food production. Facilities using unpasteurized milk should be carefully monitored to prevent this type of outbreaks.