Microorganisms responsible for periprosthetic knee infections in England and Wales

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

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

Pathogenic bacteria characteristics and drug resistance in acute, delayed, and chronic periprosthetic joint infection: A retrospective analysis of 202 patients

To assist orthopaedic surgeons in choosing appropriate antibiotics, this study attempted to identify the common microorganisms that cause periprosthetic joint infection (PJI) and their respective drug resistance spectrums. The clinical data of 202 patients with PJI after primary hip and knee arthroplasty between January 2017 and December 2021 were retrospectively analysed. There were 84 males and 118 females, aged (63.03 ± 13.10) years (range: 24-89 years). A total of 102 and 100 patients underwent total hip and total knee arthroplasty, respectively. Based on the time of postoperative infection, the patients were divided into acute (25 cases), delayed (91 cases), and chronic (86 cases) PJI groups. The results of pathogen species, composition ratio, and drug susceptibility tests were collected. Gram-positive bacteria were the primary causative pathogens of PJI (58.91%, 119/202), and their culture-positive rates in patients with acute, delayed, and chronic PJI were 32.00% (8/25), 62.64% (57/91), and 62.79% (54/86), respectively. Staphylococcus epidermidis and Staphylococcus aureus were the major gram-positive bacteria detected, followed by gram-negative bacteria (29/202, 14.36%), and fungi (4/202, 1.98%). Gram-positive bacteria showed higher resistance to penicillin (81.25%), oxacillin (63.33%), erythromycin (61.17%), and clindamycin (48.35%) and 100% sensitivity to linezolid, vancomycin, daptomycin, and tigecycline. In gram-negative bacteria, the drug resistance rates to cefazolin, gentamicin, furantoin, cefuroxime, ticacillin/clavulanic acid, ceftriaxone, ciprofloxacin, and tobramycin were >50%. However, no vancomycin-resistant bacteria were discovered in the current study. The drug resistance rate to carbapenems was low, ranging from 0% to 3.57%. Gram-positive bacteria are the main causative pathogens of PJI, and the resistance rate of pathogens of chronic PJI is higher than those of delayed and acute PJI. Use of cefuroxime and clindamycin in patients with PJIs should proceed with caution because of the high drug resistance rate. Vancomycin can be used as a first-line antibiotic against gram-positive bacteria. Carbapenems can be used as the first choice against gram-negative bacteria because of to their high sensitivity.

Effectiveness of two-stage revision with commercial polymethylmethacrylate articulated hip spacer: similar outcomes against monomicrobial and polymicrobial hip periprosthetic joint infections

Background: orthopaedic surgeons still struggle against a devastating complication - periprosthetic joint infection (PJI). A two-stage revision is considered the gold standard for chronic PJI for several authors, with success rates over 90 %. This strategy implies the remotion of the prosthesis and the implantation of an antibiotic-impregnated cement spacer in the joint. The primary objective of this study was to assess the effectiveness of a two-stage revision approach using a commercial prefabricated antibiotic-impregnated cement hip spacer for the treatment of hip PJI regarding monomicrobial and polymicrobial infections. Secondly, to assess risk factors for failure of two-stage revision. Material and methods: we conducted a retrospective study on patients that underwent revision of total hip arthroplasty (THA) between January 2002 and January 20218. We included adult patients with a diagnosis of chronic hip PJI that underwent two-stage revision using a prefabricated gentamicin-impregnated cement of polymethylmethacrylate (PMMA) hip spacer. We assessed whether it was monomicrobial or polymicrobial infections and comorbidities. Treatment success was defined when eradication of the infection was observed and no further procedures or mortality were registered after the second stage. Persistence or recurrence of infection was considered a failure of treatment. Results: the final series consisted of 84 patients treated with the same hip spacer: 60 (71.4 %) monomicrobial and 24 (28.6 %) polymicrobial joint infections with an overall follow-up of 59.0 (36.0-84.0) months. The overall success rate was 90.5 %. Eight (9.5 %) patients failed. Smoking and BMI greater than 30 m kg- 2 were identified independent risk factors for failure in multivariate analysis. Conclusion: our study suggests that prefabricated gentamicin-impregnated PMMA spacer is an effective tool for the treatment of PJI, achieving similar outcomes whether it is monomicrobial or polymicrobial infections. Randomized prospective studies are needed to obtain more reliable conclusions.

Implant surface modifications as a prevention method for periprosthetic joint infection caused by Staphylococcus aureus: a systematic review and meta-analysis

Abstract. Background: Periprosthetic joint infection is the most common infection due to joint replacement. It has been reported that, over a 5-year time span, 3.7 % of cases occurred annually. This statistic has increased to 6.86 % over 16 years. Thus, an effective method is required to reduce these complications. Several strategies such as coating methods with various materials, such as antibiotics, silver, and iodine, have been reported. However, the best preventive strategy is still undetermined. Therefore, this systematic review aims to evaluate the outcome of coating methods on joint arthroplasty as a treatment or preventive management for infection complications. Methods: Eligible articles were systematically searched from multiple electronic databases (PubMed, Cochrane library, and ScienceDirect) up to 2 June 2022. Based on the criterion inclusion, eight articles were selected for this study. The Newcastle–Ottawa scale (NOS) was used to assess the quality of the study, and the meta-analysis test was conducted with Review Manager 5.4. Results: The quality of the articles in this study is in the range of moderate to good. It was found that the application of modified antibiotic coatings significantly reduced the occurrence of periprosthetic joint infection (PJI) (p 0.03), and silver coating could not significantly (p 0.47) prevent the occurrence of PJI. However, according to the whole aspect of coating modification, the use of antibiotics, silver, and iodine can minimize the occurrence of PJI (p <0.0001). Conclusion: Coating methods using antibiotics are an effective method that could significantly prevent the occurrence of PJI. On the other hand, coating with non-antibiotic materials such as silver could not significantly prevent the incidence of PJI.

Pathogen distrbution and drug resistance in acute, delayed and chronic periprosthetic joint infection: a retrospective analysis of 202 patients.. [DOI: 10.21203/rs.3.rs-2111407/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Introduction To assist orthopedic surgeons to select appropriate antibiotics, this study identified the common microorganisms that caused PJI and their drug-resistant spectrum. Methods. The clinical data of 202 patients with PJI after primary knee and hip arthroplasty from January 2017 to December 2021 were retrospectively analyzed. According to the time of postoperative infection, the patients were divided into acute PJI group (25 cases), delayed PJI group (91 cases), and chronic PJI group (86 cases). The results of pathogen species, composition ratio, drug susceptibility tests were collected. Results.The main pathogens of PJI were Gram-positive bacteria (58.91%, 119/202), and the positive rates of culture in patients with acute PJI, delayed PJI and chronic PJI were 32.00% (8/25), 62.64% (57/91) and 62.79% (54/86), followed by gram-negative bacteria (29/202, 14.36%) and fungus (4/202, 1.98%). Staphylococcus epidermidis and Staphylococcus aureus played an important role as well, followed by gram-negative bacteria (29/202, 14.36%) and fungus (4/202, 1.98%). Penicillin (81.25%), oxacillin (63.33%), erythromycin (61.17%) and clindamycin (48.35%) showed high antibiotic resistance rate in gram-positive bacteria. The drug-sensitivity to linezolid, vancomycin, daptomycin and tigecycline was 100%. The drug resistance rate to carbapenems was low, ranging from 0 to 3.57%. Conclusions. The main pathogens of PJI are Gram-positive bacteria, and the drug resistance rate of chronic PJI is higher than that of delayed and acute PJI.

Differing Microorganism Profile in Early and Late Prosthetic Joint Infections Following Primary Total Knee Arthroplasty - Implications for Empiric Antibiotic Treatment

BACKGROUND

Prosthetic joint infection (PJI) is the leading cause of revision following total knee arthroplasty (TKA). Prior to microorganism identification, the choice of the correct empiric antibiotics is critical to treatment success. This study aims to 1) compare the microorganism and resistance profile in early and late PJIs; 2) recommend appropriate empiric antibiotics.

METHODS

A multicentre retrospective review was performed over a 15-year period. First episode PJIs were classified by both the Tsukayama Classification and Auckland Classification. For each PJI case, the causative organism and antibiotic sensitivity were recorded.

RESULTS

Of eligible patients, 232 culture-positive PJI cases were included. Using either classification system, early PJIs (<4 weeks or <1 year since primary) were significantly more likely to be resistant and polymicrobial. The predominant organisms were coagulase-negative Staphylococci in early PJIs while Staphylococcus aureus was the most common in late PJIs. The distribution of gram-negative cases was higher in early Class-A than late Class-C PJIs (25% versus 6%, P = .004). Vancomycin provided significantly superior coverage when compared to Flucloxacillin for early infections, and addition of a gram-negative agent achieved coverage over 90% using both classification systems.

CONCLUSION

Based on the microbiological pattern in Tsukayama criteria, Vancomycin with the consideration of Gram-negative agent should be considered for Class-A infections given the high proportion of resistant and polymicrobial cases. For Class-C infections, Cephazolin or Flucloxacillin is likely sufficient. We recommend antibiotics to be withheld in Class-B infections until cultures and sensitivities are known.

Antifungal-Loaded Acrylic Bone Cement in the Treatment of Periprosthetic Hip and Knee Joint Infections: A Review

Little is known about the clinical use of antifungal-loaded acrylic bone cement in the treatment of periprosthetic hip and knee joint infections (PJIs). Hence, we performed a literature search using PubMed/MEDLINE from inception until December 2021. Search terms were “cement” in combination with 13 antifungal agents. A total of 10 published reports were identified, which described 11 patients and 12 joints in which antifungal-loaded cement was employed. All studies were case reports or case series, and no randomized controlled trials were identified. In 6 of 11 patients, predisposing comorbidities regarding the emergence of a fungal PJI were present. The majority of the studies reported on infections caused by Candida species. In six cases (seven joints), the cement was solely impregnated with an antifungal, but no antibiotic agent (amphotericin B, voriconazole, and fluconazole). In the other five joints, the cement was impregnated with both antibiotic(s) and antifungals. Great discrepancies were seen regarding the exact loading dose. Four studies investigated the local elution of antifungal agents in the early postoperative period and observed a local release of antifungals in vivo. We conclude that there is a paucity of data pertaining to the clinical use of antifungal-loaded bone cement, and no studies have assessed the clinical efficacy of such procedures. Future studies are urgently required to evaluate this use of antifungals in PJI.

Occurrence of Rare Pathogens at the Site of Periprosthetic Hip and Knee Joint Infections: A Retrospective, Single-Center Study

The frequency and clinical relevance of rare pathogens at the site of periprosthetic infections of the hip and knee joint and their antibiotic resistance profiles have not yet been assessed in-depth. We retrospectively analyzed all periprosthetic hip and knee joint infections that occurred between 2016 and 2020 in a single center in southwest Germany. Among 165 infections, 9.7% were caused by rare microorganisms such as Veilonella sp., Pasteurella sp., Pantoea sp., Citrobacter koseri, Serratia marcescens, Parvimonas micra, Clostridium difficile, Finegoldia magna, Morganella morganii, and yeasts. No resistance to piperacillin/tazobactam, carbapenemes, fluoroquinolones, or gentamicin was observed. Some bacteria displayed resistance to ampicillin, ampicillin/sulbactam, and cefuroxime. We present follow-up data of patients with infections due to rare pathogens and discuss the importance of close, interdisciplinary collaboration between orthopedic surgeons and clinical microbiologists to carefully select the most appropriate anti-infective treatment regimens for the increasing number of patients with such infections.

Microbiology of Periprosthetic Hip and Knee Infections in Surgically Revised Cases from 34 Centers in Mainland China

Background and Aim

Periprosthetic joint infection (PJI) is one of the most devastating complications after total joint arthroplasty (TJA). However, the antibiotic resistance of infecting pathogens can significantly vary in different parts of the country. In the current study, we analyzed the demographic and microbiological profiles of knee and hip PJI over three years and compared the microbiological differences between them.

Methods

A multicenter retrospective study of PJI patients in 34 referral medical centers in mainland China from January 2015 to November 2017 was performed.

Results

A total of 925 PJI patients were recruited, 452 were identified as knee PJIs, and 473 were hip PJIs. The most common causative pathogens were Staphylococcus aureus (26.5%) and coagulase-negative staphylococci (14.3%). Methicillin-resistant staphylococci were involved in 25.6% (237/925) of all PJI cases. Mycobacterium and fungus only accounted for 6.5% (61) of all cases. Enteric gram-negative bacilli, anaerobes, and polymicrobial pathogens were more common in hip joint prostheses than in knee PJI (P = 0.014; P = 0.006; P = 0.002, respectively).

Conclusion

While the majority of causative pathogens in PJI cases are staphylococcal species, the prevalence of atypical organisms and resistant pathogens should also be given attention and warrant the need for empiric antibiotic treatment.

International Organism Profile of Periprosthetic Total Hip and Knee Infections

BACKGROUND

There is scarce literature describing pathogens responsible for periprosthetic joint infections (PJIs) around the world. Therefore, we sought to describe periprosthetic joint infection causative organisms, rates of resistant organisms, and polymicrobial infections at 7 large institutions located in North/South America and Europe.

METHODS

We performed a retrospective study of 654 periprosthetic hip (n = 361) and knee (n = 293) infections (January 2006 to October 2019) identified at Cleveland Clinic Ohio/Florida in the United States (US) (n = 159), Hospital Italiano de Buenos Aires in Argentina (n = 99), Hospital Asociación Española in Uruguay (n = 130), Guy's and St Thomas' Hospital in the United Kingdom (UK) (n = 103), HELIOS Klinikum in Germany (n = 59), and Vreden Institute for Orthopedics in St. Petersburg, Russia (n = 104). Analyses were performed for the entire cohort, knees, and hips. Alpha was set at 0.05.

RESULTS

Overall, the most frequent organisms identified were Staphylococcus aureus (24.8%) and Staphylococcus epidermidis (21.7%). The incidence of organisms resistant to at least one antibiotic was 58% and there was a significant difference between hips (62.3%) and knees (52.6%) (P = .014). Rates of resistant organisms among countries were 37.7% (US), 66.7% (Argentina), 71.5% (Uruguay), 40.8% (UK), 62.7% (Germany), and 77.9% (Russia) (P < .001). The overall incidence of polymicrobial infections was 9.3% and the rates across nations were 9.4% in the US, 11.1% in Argentina, 4.6% in Uruguay, 4.9% in UK, 11.9% in Germany, and 16.3% in Russia (P = .026).

CONCLUSION

In the evaluated institutions, S aureus and S epidermidis accounted for almost 50% of all infections. The US and the UK had the lowest incidence of resistant organisms while Germany and Russia had the highest. The UK and Uruguay had the lowest rates of polymicrobial infections.

Preoperative joint aspiration culture results and causative pathogens in total hip and knee prosthesis infections: mind the gap

OBJECTIVES

In prosthetic joint infections (PJIs), there is no consensus about the utility of the preoperative joint aspiration culture to guide antimicrobial treatment. The main objective of this retrospective study was to investigate the value of these preoperative samples to narrow immediate postoperative empirical antimicrobial treatment in patients with a knee or hip PJI.

METHODS

Adult patients admitted for an exchange procedure between June 2007 and July 2016 for whom a preoperative joint aspiration within 6 months prior to the procedure was available and with an antibiotic-free interval before sampling, were eligible. Per PJI, taking both preoperative joint aspiration and intraoperative deep samples into account, causative pathogen(s) were assessed by the current Infectious Diseases Society of America (IDSA) guidelines. Per PJI, agreement of preoperative joint aspiration cultures corresponding to the causative pathogen(s) was investigated both on species and on Gram/fungi level.

RESULTS

From the 85 PJIs, on species level, the total agreement was found in 58 (68%) PJIs. On Gram/fungi level, when preoperative joint aspiration cultures yielded exclusively Gram-positive microorganisms (n = 61), a 100% predictive value for Gram positive causing pathogens was attained. Insufficient predictive value was observed in PJIs with preoperative joint aspiration yielding Gram-negative microorganisms (n = 4), a fungus (n = 1) or with sterile results (n = 19).

CONCLUSION

In the immediate postoperative setting, the treating team might consider a broad spectrum empirical antibiotic regime, guided by the local epidemiology and susceptibility, which can be narrowed to Gram-positive coverage if preoperative joint aspiration cultures yield exclusively Gram-positive microorganisms.

Factors affecting the incidence of surgical site infection after geriatric hip fracture surgery: a retrospective multicenter study

Background

Geriatric hip fracture is a common type of osteoporotic fracture with high mortality and disability; surgical site infection (SSI) can be a devastating complication of this injury. By far, only a few studies identified easily remediable factors to reduce infection rates following hip fracture and less researches have focused on geriatric patients. The objective of this study was to identify potentially modifiable factors associated with SSI following geriatric hip fracture surgery.

Methods

This retrospective, multicenter study involves three level I hospitals. A total of 1240 patients (60 years or older) underwent hip surgery with complete data were recruited between January 2016 and June 2018. Demographics information, medications and additional comorbidities, operation-related variables, and laboratory indexes were extracted and analyzed. Receiver operating characteristic (ROC) analysis was performed to detect the optimum cut-off value for quantitative data. Univariate and multivariate logistic analysis model were performed respectively to identify the independent predictors.

Results

Ninety-four (7.58%) patients developed SSI in this study, and 76 (6.13%) had superficial infection, while 18 (1.45%) were diagnosed with deep infection. Results of univariate and multivariate analysis showed age > 79 years (OR, 2.60; p < 0.001), BMI > 26.6 kg/m² (OR, 2.97; p < 0.001), operating time > 107 min (OR, 2.18; p = 0.001), and ALB < 41.6 g/L (OR, 2.01; p = 0.005) were associated with an increased incidence of SSI; drainage use (OR, 0.57; p = 0.007) could reduce the incidence of wound infection for patients after geriatric hip fracture.

Conclusion

Accurate modifiable variables, operating time > 107 min, serum albumin < 41.6 g/L, BMI > 26.6 kg/m², and age > 79 years could be applied to distinguish geriatric patients with high-risk of postoperative surgical site infection.

Is surface modification effective to prevent periprosthetic joint infection? A systematic review of preclinical and clinical studies

BACKGROUND

With increasing recognition of the importance of biofilm formation in the pathogenesis of periprosthetic joint infection (PJI), a push towards finding solutions to prevent PJI via surface modification of prostheses is occurring. Unlike the promising in vitro antimicrobial effects of these surface modifications, the preclinical and clinical prophylactic effects vary and are debated. Therefore, we performed this systematic review to answer: (1) what kinds of methods of surface modification are used in preclinical and clinical studies to prevent PJI, (2) whether these modifications are effective to prevent PJI.

METHODS

Electronic searches were performed using PubMed, Embase and the Cochrane library databases up to and including December 2017 with predetermined criteria: (1) in vivo studies with (2) surface modification for prophylactic effects against infection. Both animal studies and clinical trials were included. Data were extracted and presented systematically.

RESULTS

Overall, 21 studies were included. Among these, fourteen were carried out in animal models and seven were clinical studies. In the animal studies, six used antibiotics and six silver modifications, while copper and Cationic Steroidal Antimicrobial-13 were each used for one study. In the seven clinical studies targeting patients with high infection risk, five of them focused on silver-coated prostheses and the remaining two studied iodine-coated implants. In all of the animal studies, when compared with the control group, the surface modified groups had a lower infection risk (RR ranging from 0 to 0.71). Clinical studies using silver-coated prostheses also demonstrated a lower infection risk (RR ranging from 0.24 to 0.70), while iodine-coated implants showed a 0% and 5% incidence of PJI in the two case series included.

DISCUSSION

The results from the publications included in this review indicate that surface modification, especially antibiotic and silver modifications, are helpful preventing PJI in both preclinical animal models and in clinical trials.

LEVEL OF EVIDENCE

III, systematic review of level III retrospective comparative studies and level IV case series and animal experiments.

Risk factors associated with revision for prosthetic joint infection following knee replacement: an observational cohort study from England and Wales

Background

Prosthetic joint infection is a devastating complication of knee replacement. The risk of developing a prosthetic joint infection is affected by patient, surgical, and health-care system factors. Existing evidence is limited by heterogeneity in populations studied, short follow-up, inadequate power, and does not differentiate early prosthetic joint infection, most likely related to the intervention, from late infection, more likely to occur due to haematogenous bacterial spread. We aimed to assess the overall and time-specific associations of these factors with the risk of revision due to prosthetic joint infection following primary knee replacement.

Methods

In this cohort study, we analysed primary knee replacements done between 2003 and 2013 in England and Wales and the procedures subsequently revised for prosthetic joint infection between 2003 and 2014. Data were obtained from the National Joint Registry linked to the Hospital Episode Statistics data in England and the Patient Episode Database for Wales. Each primary replacement was followed for a minimum of 12 months until the end of the observation period (Dec 31, 2014) or until the date of revision for prosthetic joint infection, revision for another indication, or death (whichever occurred first). We analysed the data using Poisson and piecewise exponential multilevel models to assess the associations between patient, surgical, and health-care system factors and risk of revision for prosthetic joint infection.

Findings

Of 679 010 primary knee replacements done between 2003 and 2013 in England and Wales, 3659 were subsequently revised for an indication of prosthetic joint infection between 2003 and 2014, after a median follow-up of 4·6 years (IQR 2·6–6·9). Male sex (rate ratio [RR] for male vs female patients 1·8 [95% CI 1·7–2·0]), younger age (RR for age ≥80 years vs <60 years 0·5 [0·4–0·6]), higher American Society of Anaesthesiologists [ASA] grade (RR for ASA grade 3–5 vs 1, 1·8 [1·6–2·1]), elevated body-mass index (BMI; RR for BMI ≥30 kg/m²vs <25 kg/m² 1·5 [1·3–1·6]), chronic pulmonary disease (RR 1·2 [1·1–1·3]), diabetes (RR 1·4 [1·2–1·5]), liver disease (RR 2·2 [1·6–2·9]), connective tissue and rheumatic diseases (RR 1·5 [1·3–1·7]), peripheral vascular disease (RR 1·4 [1·1–1·7]), surgery for trauma (RR 1·9 [1·4–2·6]), previous septic arthritis (RR 4·9 [2·7–7·6]) or inflammatory arthropathy (RR 1·4 [1·2–1·7]), operation under general anaesthesia (RR 1·1 [1·0–1·2]), requirement for tibial bone graft (RR 2·0 [1·3–2·7]), use of posterior stabilised fixed bearing prostheses (RR for posterior stabilised fixed bearing prostheses vs unconstrained fixed bearing prostheses 1·4 [1·3–1·5]) or constrained condylar prostheses (3·5 [2·5–4·7]) were associated with a higher risk of revision for prosthetic joint infection. However, uncemented total, patellofemoral, or unicondylar knee replacement (RR for uncemented vs cemented total knee replacement 0·7 [95% CI 0·6–0·8], RR for patellofemoral vs cemented total knee replacement 0·3 [0·2–0·5], and RR for unicondylar vs cemented total knee replacement 0·5 [0·5–0·6]) were associated with lower risk of revision for prosthetic joint infection. Most of these factors had time-specific effects, depending on the time period post-surgery.

Interpretation

We have identified several risk factors for revision for prosthetic joint infection following knee replacement. Some of these factors are modifiable, and the use of targeted interventions or strategies could lead to a reduced risk of revision for prosthetic joint infection. Non-modifiable factors and the time-specific nature of the effects we have observed will allow clinicians to appropriately counsel patients preoperatively and tailor follow-up regimens.

Funding

National Institute for Health Research.

Staphylococcal resistance profiles in deep infection following primary hip and knee arthroplasty: a study using the NJR dataset

INTRODUCTION

This study aimed to (1) report the rates of resistance against a variety of antibiotics for pure Staphylococcal infections, and (2) examine the impact of ALBC use at primary surgery has on resistance patterns for patients undergoing first-time revision of primary hip and knee arthroplasty for indication of infection.

MATERIALS AND METHODS

Data from the National Joint Registry database for England and Wales were linked to microbiology data held by Public Health England to identify a consecutive series of 258 primary hip and knee arthroplasties performed between April 2003 and January 2014 that went on to have a revision for Staphylococcal deep periprosthetic infection. Multivariate binary logistic regression was used to study predictors of microorganism resistance to a range of antimicrobials.

RESULTS

After adjusting for patient and surgical factors, multivariate analysis showed the use of gentamicin-loaded bone cement at the primary surgery was associated with a significant increase in the risk of Staphylococcal gentamicin resistance (odds ratio 8.341, 95% CI 2.297-30.292, p = 0.001) and methicillin resistance (odds ratio 3.870, 95% CI 1.319-11.359, p = 0.014) at revision for infection.

CONCLUSIONS

Clinicians must anticipate the possibility of antibiotic resistance to ALBC utilised at primary surgery.

Bi-functional titanium-polydopamine-zinc coatings for infection inhibition and enhanced osseointegration

The ideal orthopedic implant coating is expected to both inhibit microbial infection and promote osseointegration. In this study, Zn ions were immobilized on a Ti substrate via a polydopamine (PDA) chemical surface modification to prepare Ti-PDA-Zn coatings. Scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscope (EDS), X-ray photoelectron spectroscopy (XPS), contact analysis system, and inductively coupled plasma atomic emission spectrometry (ICP-AES) were used to analyze the morphology, composition, wettability, and zinc ions release of the coatings. The Ti-PDA-Zn coatings demonstrated excellent antibacterial activities in vitro against both Staphylococcus aureus and Escherichia coli. The coatings additionally displayed good biocompatibility, as confirmed by cytoskeletal observations and cell viability assays. Furthermore, the in vivo results confirmed the excellent antibacterial properties and improved osseointegration capability of the Ti-PDA-Zn coating in the presence of S. aureus. The present findings indicate that the Ti-PDA-Zn coatings prepared herein have potential application in orthopedic implantation.

The ideal orthopedic implant coating is expected to both inhibit microbial infection and promote osseointegration.

Significant increase of pathogen detection rate by dry arthroscopic biopsies at suspected low-grade infection following total knee arthroplasty: a prospective observational study

INTRODUCTION

The differentiation between stiff-knee and low-grade periprosthetic joint infection (PJI) is the current diagnostic challenge in total knee (TKA) revision arthroplasty. The aim of this study was to investigate the additional value of dry biopsies, compared to wet biopsies, in patients presenting with knee stiffness following primary TKA.

MATERIALS AND METHODS

Single center, prospective observational study. Consecutive patients with joint stiffness of unknown origin following primary TKA were enrolled. Patient assessment followed the diagnostic standard algorithm. During diagnostic arthroscopy, synovial fluid (synovial WBC, PMN%) and five dry biopsies (dry) were collected. Then fluid was infused and another five microbiology (wet) and five histological biopsies gathered, all from identical locations. The primary outcome parameter was the difference between the pathogens in wet and dry biopsies.

RESULTS

71 patients (61% females, 67 ± 10 years) were eligible. Preoperative blood serology mean CRP (0.7 ± 1.5 mg/dl; p = 0.852), WBC (6.6 ± 1.7 G/l; p = 0.056), and synovial fluid mean WBC (1639 ± 2111; p = 0.602), PMN% (38 ± 28; p = 0.738) did not differ between patients with negative, positive wet or dry biopsies. The histology was in 11% positive (p = 0.058). In 32% at least one pathogen was detected, 48% from wet, 44% from dry biopsies. An inhomogeneous distribution was found. Cutibacterium acnes (100%) was solely found in wet, Micrococcus luteus (75%), Staphylococcus capitis (67%), and Micrococcus lylae (100%) were predominantly found in dry biopsies. Additional dry biopsies increased the pathogen detection rate by 49%.

CONCLUSION

The addition of dry biopsies to the current standard diagnostic algorithm for PJI increased the pathogen detection rate by 49%.

The effectiveness of ultra-clean air operating theatres in the prevention of deep infection in joint arthroplasty surgery

Deep infection was identified as a serious complication in the earliest days of total hip arthroplasty. It was identified that airborne contamination in conventional operating theatres was the major contributing factor. As progress was made in improving the engineering of operating theatres, airborne contamination was reduced. Detailed studies were carried out relating airborne contamination to deep infection rates.

In a trial conducted by the United Kingdom Medical Research Council (MRC), it was found that the use of ultra-clean air (UCA) operating theatres was associated with a significant reduction in deep infection rates. Deep infection rates were further reduced by the use of a body exhaust system. The MRC trial also included a detailed microbiology study, which confirmed the relationship between airborne contamination and deep infection rates.

Recent observational evidence from joint registries has shown that in contemporary practice, infection rates remain a problem, and may be getting worse. Registry observations have also called into question the value of “laminar flow” operating theatres.

Observational evidence from joint registries provides very limited evidence on the efficacy of UCA operating theatres. Although there have been some changes in surgical practice in recent years, the conclusions of the MRC trial remain valid, and the use of UCA is essential in preventing deep infection.

There is evidence that if UCA operating theatres are not used correctly, they may have poor microbiological performance. Current UCA operating theatres have limitations, and further research is required to update them and improve their microbiological performance in contemporary practice.

Cite this article: Bone Joint J 2018;100-B:1264–9.

Analysis of postoperative and hematogenous prosthetic joint-infection microbiological patterns in a large cohort

OBJECTIVES

This study was undertaken to analyze prosthetic joint infection (PJI)-causing microorganisms and compare their distribution patterns according to PJI classification.

METHODS

Cohort study from a single referral center for bone-and-joint infections from January 2004 to December 2015.

RESULTS

Nine hundred and twenty-six patients, who developed 997 PJIs, involving the hip (62%), knee (35%) and/or shoulder (1%), were included. PJIs were classified as early postoperative (19%), late chronic (30%), hematogenous (35%) and undetermined (16%). Pathogens most frequently isolated from early-postoperative PJIs were staphylococci (57%), with 25% each Staphylococcus aureus or Staphylococcus epidermidis; 21% were polymicrobial and 10% Gram-negative rods. For late-chronic PJIs, the most frequent microbes were staphylococci (61%), predominantly S. epidermidis (35%); anaerobic bacteria were isolated from 15%; 11% were polymicrobial. Hematogenous PJIs were 99% monomicrobial. Although S. aureus was the most frequently isolated species (28%), streptococci were isolated slightly more often than staphylococci (39% vs. 36%). Among streptococci, group B streptococci were the most frequent (15%). The portal of entry was identified for 52% of hematogenous PJIs: 15% cutaneous, 11% dental, 9% gastrointestinal, 6% urinary, and 11% miscellaneous.

CONCLUSION

Although a wide variety of microorganisms was isolated from PJIs, specific microbiological patterns were observed according to infection classification.

The burden of seasonal respiratory infections on a national telehealth service in England

Seasonal respiratory illnesses present a major burden on primary care services. We assessed the burden of respiratory illness on a national telehealth system in England and investigated the potential for providing early warning of respiratory infection. We compared weekly laboratory reports for respiratory pathogens with telehealth calls (NHS 111) between week 40 in 2013 and week 29 in 2015. Multiple linear regression was used to identify which pathogens had a significant association with respiratory calls. Children aged <5 and 5-14 years, and adults over 65 years were modelled separately as were time lags of up to 4 weeks between calls and laboratory specimen dates. Associations with respiratory pathogens explained over 83% of the variation in cold/flu, cough and difficulty breathing calls. Based on the first two seasons available, the greatest burden was associated with respiratory syncytial virus (RSV) and influenza, with associations found in all age bands. The most sensitive signal for influenza was calls for 'cold/flu', whilst for RSV it was calls for cough. The best-fitting models showed calls increasing a week before laboratory specimen dates. Daily surveillance of these calls can provide early warning of seasonal rises in influenza and RSV, contributing to the national respiratory surveillance programme.

Distribution characteristics of Staphylococcus spp. in different phases of periprosthetic joint infection: A review

Periprosthetic joint infection (PJI) is a devastating condition and Staphylococcus spp. are the predominant pathogens responsible, particularly coagulase-negative staphylococci (CoNS) and Staphylococcus aureus. The aim of the present systematic review was to evaluate the distribution characteristics of specific Staphylococcus spp. in different PJI phases, reveal the effect of pathogens' feature on their distribution and suggest recommendations for antibiotic treatment of Staphylococcal PJI. The present systematic review was performed using PubMed and EMBASE databases with the aim to identify existing literature that presented the spectrum of Staphylococcus spp. that occur in PJI. Once inclusion and exclusion criteria were applied, 20 cohort studies involving 3,344 cases in 3,199 patients were included. The predominant pathogen involved in PJI was indicated to be CoNS (31.2%), followed by S. aureus (28.8%). This trend was more apparent in hip replacement procedures. In addition, almost equal proportions of CoNS and S. aureus (28.6 and 30.0%, respectively) were indicated in the delayed phase. CoNS (36.6%) were the predominant identified organism in the early phase, whereas S. aureus (38.3%) occurred primarily in the late phase. In PJI caused by S. aureus, the number of cases of methicillin-sensitive Staphylococcus aureus (MSSA) was ~2.5-fold greater than that of methicillin-resistant Staphylococcus aureus (MRSA). MRSA occurred predominantly in the early phase, whereas MSSA was largely observed in the delayed and late phases. With regards to antibiotic treatment, the feature of various pathogens and the phases of PJI were the primary considerations. The present review provides useful information for clinical practice and scientific research of PJI.

Chronic periprosthetic hip infection: micro-organisms responsible for infection and re-infection

PURPOSE

This study aimed to delineate the infecting micro-organisms identified at the first-time revision for infected THA, analyze pre-operative versus intra-operative findings, as well as intra-operative ones against re-infection micro-organisms.

MATERIAL AND METHODS

Microbiological laboratory findings were studied in 73 patients (mean age, 51.93 ± 10.9 years) with chronic periprosthetic hip infection pre-operatively and intra-operatively. Forty-three patients had a two-stage revision THA while 30 patients were treated with a modified resection arthroplasty using the Ilizarov apparatus. Re-infection developed in 29 cases. Its microbial species were identified.

RESULTS

Pre-operative findings on micro-organisms coincided 50.7 % with the intra-operative ones. Bacterial growth in the intra-operative tests was detected in 72 (98.5 %) cases. Gram-positive single genus infection was identified in 35 patients (48 %); microbe associations were present in 33 patients (45 %). Staphylococcus species prevailed. Gram-negative infection was detected in 5.5 % of cases. One case (1.5 %) did not have any microbe growth. Re-infection happened in 10 cases (23.2 %) in a two-stage revision THA. In the resection arthroplasty group, early re-infection was observed in 63.3 % of cases. Among a total of 29 re-infection cases, staphylococcus species were identified in 19 cases, present either in associations or as single germs.

CONCLUSION

Intra-operative microbiological tests at the first-time revision for infected THR detect a reliable spectrum of micro-organisms to assess microbial resistance to antibiotics, develop treatment protocols, and for prognostic purposes. Preventive measures at primary THR and strategies to fight periprosthetic infection and reinfection should be targeted on staphylococci.

Does pre-operative sampling predict intra-operative cultures and antibiotic sensitivities in knee replacements revised for infection?: a study using the NJR dataset

PURPOSE

This study examined a cohort of primary knee arthroplasties revised for peri-prosthetic infection to (1) determine whether the microorganisms isolated by sampling (up to 6 months pre-operatively) are representative of the microorganisms encountered at the time of knee revision, (2) determine whether the antibiotic sensitivity profiles of matching organisms correlate and (3) determine whether the proportion of organism and antibiotic sensitivity matches is influenced by the type of infection, timing of sample collection and the type of microorganism isolated.

METHODS

From the National Joint Registry database for England and Wales, a consecutive series of primary knee arthroplasties performed between 2003 and 2014 that went on to have a revision for peri-prosthetic infection were identified. Each case was then linked to a national microbiology database held by Public Health England. Following data linkage, intra-operative and pre-operative cultures were identified and compared in a group of 75 patients.

RESULTS

Pre-operative genus matched intra-operative genus in 56 of 75 cases (75 %). Of those 56, the corresponding antimicrobial sensitivities matched in 37 (66 % of cases). Overall, 37 of 75 cases (49 %) matched for both microorganism and antimicrobial sensitivity. The proportion of matches was highest in the pure Staphylococcal genus infections (genus match 88 %, sensitivity match 62 %, genus and sensitivity match 55 %) and lowest in those patients with mixed organism infections (genus match 29 %, sensitivity match 14 %).

CONCLUSION

Pre-operative joint sampling obtained by either aspiration or tissue biopsy is advocated in cases where peri-prosthetic infection is suspected and provides the only means of determining infecting organism prior to revision. Overall, only half of all pre-operative cultures matched completely the findings of intra-operative samples in terms of both the microorganism(s) encountered and their corresponding antimicrobial sensitivity profile. Clinicians should be vigilant regarding the possibility of the patient acquiring further microorganisms or the development of new antibiotic resistance by the time of revision, especially in historic pre-operative cultures. Broad spectrum antibiotic therapies should therefore be employed until final microorganisms and antimicrobial sensitivities are confirmed from intra-operative samples.

LEVEL OF EVIDENCE

IV.

Bacteriophage-driven inhibition of biofilm formation in Staphylococcus strains from patients attending a Romanian reference center for infectious diseases

The increasing burden of invasive biofilm-related staphylococcal infections has led to a dire need for new agents to prevent biofilm formation. Bacteriophages may hypothetically alter a biofilm through several mechanisms, including induction of depolymerizing enzymes and lysis of persistent bacteria. We have assessed the influence of commercially available bacteriophage cocktails on Staphylococcus spp. clinical strains viability and biofilm formation. We analyzed 83 staphylococcal strains from patients consecutively admitted to a Romanian infection reference center from October 2014 through May 2015; the strains were characterized by phenotypic and genetic tools for their resistance and virulence features and for their phyliation. Experiments were performed in triplicate. Methicillin-susceptible strains were significantly more susceptible to all tested phages: 1.7-fold higher susceptibility for PYO, 1.4-fold for INTESTI, 2.9-fold for PHAGYO, 2.7-fold for PHAGESTI and 3.9-fold for STAPHYLOCOCCAL; t030 strains were significantly more susceptible to PYO and INTESTI compared with t127 strains. We identified a significant decrease in biofilm formation in the presence of both low and high PYO and INTESTI concentrations (P < 0.001). In conclusion, Staphylococcus strains from Romania displayed fairly good susceptibility to commercially available bacteriophages. We have also ascertained there is phage-driven in vitro inhibition of biofilm formation, the results potentially impacting prevention of prosthetic infections.