Trends in surgical site infections following orthopaedic surgery

Do We Need Routine Postoperative Prophylactic Oral Antibiotics in Elective Foot and Ankle Surgery?

Background

Previous studies about antibiotic prophylaxis in foot and ankle surgery have focused on perioperative intravenous administration, with few studies reporting on the efficiency of postoperative oral antibiotics. The purpose of this study is to investigate differences in the rate of postoperative infection and wound complications between patients with and without postoperative oral antibiotics and to identify independent risk factors for these complications following foot and ankle surgeries.

Methods

A retrospective review of all elective foot and ankle surgeries with at least a 6-month follow-up was performed over a 2-year time span. Patients were divided into 2 groups based on if they received postoperative oral antibiotics. We compared the rates of postoperative infections and wound complications between the 2 groups. The surgical site, the number of Current Procedural Terminology codes, and the number of surgical incisions were also noted. Multivariable logistic regression analysis was performed to identify independent risk factors of postoperative infection and wound complications.

Results

A total of 366 patients were included in this study-240 with antibiotics and 126 without antibiotics. There was no significant difference in the rates of postoperative infection and wound complications between the 2 groups. The rate of superficial infection, deep infection, and wound complications was 1.7%, 0.8%, and 5.8% in the antibiotic group vs 3.2%, 0.0%, and 4.0% in patients without antibiotics, respectively. Multivariable logistic regression analysis identified independent risk factors of postoperative infection and wound complications as follows: smoking (OR: 4.7), male (OR: 4.0), history of neoplasm (OR: 6.7), and multiple incisions (OR: 4.1).

Conclusion

Our results suggest that routine postoperative prophylactic oral antibiotics are not needed following elective foot and ankle surgeries. However, certain risk factors may increase the risk for postoperative infection and wound complications in foot and ankle surgery.

Level of Evidence

Level III, case-control study.

Introduction of a New Protocol to Limit the Number of Cancelled Elective Orthopaedic Operations Due to Asymptomatic Bacteriuria

Background Asymptomatic bacteriuria (ASB) poses a significant diagnostic dilemma for medical professionals. Current hospital screening protocol determines the likelihood of a positive diagnosis of a urinary tract infection (UTI) based on the results of a bedside urinalysis. ASB, defined as a positive urine culture in the absence of symptoms, can contribute to unnecessary cancellations, poor utilisation of theatre time, and delayed patient care. We present a two-cycle audit proposing a new pathway to addressing ASB in patients awaiting elective orthopaedic surgery, aiming to optimise surgical yield. Our objectives are to identify areas for improvement in our departmental practices with respect to asymptomatic bacteria compared to the published literature. We propose a new protocol targeted to improve our current practices to minimise patient cancellations and optimise theatre utilisation. Methodology A total of 78 patients who had an elective orthopaedic procedure cancelled at a large district general hospital offering tertiary orthopaedic services, between two study periods spanning March 2018 to April 2019 and May 2019 to March 2020, were identified from electronic hospital records and theatre management systems. Demographics, procedure details, and reasons for cancellations, including the result of urinalysis and the presence of UTI symptoms were assessed. Our pathway was introduced after the first study period and, subsequently, re-audited to assess adherence to the new protocol and its effect on cancellations. Results We identified 78 patients, with a 50:50 male:female split and an average age of 63 (range = 9-90). Of the 33 patients in the first cohort, seven (21.2%) were cancelled due to UTI risk based on positive urinalysis. Of these seven cancellations, one (14.3%) patient reported symptoms of a UTI. The second cohort comprised 45 patients, two (4.4%) of whom were cancelled due to UTI risk based on symptom questionnaire results. These two symptomatic patients along with another two asymptomatic patients (8.8% in total) were found to have positive urinalyses; however, the two asymptomatic patients had their operations cancelled for unrelated reasons. Conclusions The study has shown that previously of all patients awaiting elective orthopaedic operations who had their procedures cancelled, 85.7% were cancelled due to ASB. After the introduction of a new protocol focussing on symptoms rather than urinalysis, we estimate that the number of cancelled elective orthopaedic operations has reduced by 71.4%, thereby greatly improving the utilisation of theatre time.

Prevalence and associated factors of infection after intramedullary nailing of long bone fractures among patients attending St. Paul's Hospital Millennium Medical College, AaBET Hospital, Addis Ababa, Ethiopia

Objectives

The intramedullary nailing of long bone fractures is a major challenge for orthopedic surgeons, with increased risk of infection in third-world countries. Research gaps remain in Ethiopia, determining the magnitude of the problem. This study aimed to determine the prevalence and associated factors of infection after intramedullary nailing of long bone fractures in Ethiopia.

Methods

This was a descriptive, cross-sectional, retrospective design study with a total census of 227 cases of long bone fractures treated with intramedullary Surgical Implant Generation Network nails at Addis Ababa Burn Emergency and Trauma Hospital from August 2015 to April 2017. Data were collected from 227 patients and descriptive analyses were done to summarize the study variables. Binary and multivariable logistic regression analyses were performed at a p value of 0.05 with a 95% confidence interval and adjusted odds ratio.

Results

The mean age of patients was 32.9 years, with a male-to-female ratio of 3.5:1. Only 22 (9.3%) of the 227 patients with long bone fractures treated with intramedullary nails developed a surgical site infection, and 8 (3.4%) were developed deep (implant) infections requiring debridement. Road traffic injuries were the leading cause of trauma (60.9%), followed by falls from a height (22.7%). Debridement was done within 24 h for 52 (61.9%) and within 72 h for 69 (82.1%) patients with open fractures. Only 19 (22.4%) and 55 (64.7%) patients with open fractures and tibial long bone fractures received antibiotics within 3 h. Open fractures and tibial fractures had higher percentages of infection, 18.6% and 12.1%, respectively. Previous use of an external fixator (44.4%) and prolonged surgery (12.5%) were associated with higher proportions of infection.

Conclusion

This study found that the prevalence of infections after intramedullary nailing of long bone fractures in Ethiopia was 44.4% after external fixation, compared to 6.4% after intramedullary nail was inserted directly. Proper control measures are needed to reduce morbidity and complications related to long fracture treatment, such as open fractures, tibial fractures, the use of an external fixator, delayed debridement and skin closure, and prolonged surgery developed surgical site infection rate.

Microporous Implants Modified by Bifunctional Hydrogel with Antibacterial and Osteogenic Properties Promote Bone Integration in Infected Bone Defects

Prosthesis implantation and bone integration under bacterial infection are arduous challenges in clinical practice. It is well known that the reactive oxygen species (ROS) produced by bacterial infection around the bone defects will further hinder bone healing. To solve this problem, we prepared a ROS-scavenging hydrogel by cross-linking polyvinyl alcohol and a ROS-responsive linker, N¹-(4-boronobenzyl)-N³-(4-boronophenyl)-N¹, N¹, N³, N³-tetramethylpropane-1, 3-diaminium, to modify the microporous titanium alloy implant. The prepared hydrogel was used as an advanced ROS-scavenging tool to promote bone healing by inhibiting the ROS levels around the implant. Bifunctional hydrogel serving as a drug delivery system can release therapeutic molecules, including vancomycin, to kill bacteria and bone morphogenetic protein-2 to induce bone regeneration and integration. This multifunctional implant system that combines mechanical support and disease microenvironment targeting provides a novel strategy for bone regeneration and integration of implants in infected bone defects.

Bioactive compounds: a goldmine for defining new strategies against pathogenic bacterial biofilms?

Most human infectious diseases are caused by microorganisms growing as biofilms. These three-dimensional self-organized communities are embedded in a dense matrix allowing microorganisms to persistently inhabit abiotic and biotic surfaces due to increased resistance to both antibiotics and effectors of the immune system. Consequently, there is an urgent need for novel strategies to control biofilm-associated infections. Natural products offer a vast array of chemical structures and possess a wide variety of biological properties; therefore, they have been and continue to be exploited in the search for potential biofilm inhibitors with a specific or multi-locus mechanism of action. This review provides an updated discussion of the major bioactive compounds isolated from several natural sources - such as plants, lichens, algae, microorganisms, animals, and humans - with the potential to inhibit biofilm formation and/or to disperse established biofilms by bacterial pathogens. Despite the very large number of bioactive products, their exact mechanism of action often remains to be clarified and, in some cases, the identity of the active molecule is still unknown. This knowledge gap should be filled thus allowing development of these products not only as novel drugs to combat bacterial biofilms, but also as antibiotic adjuvants to restore the therapeutic efficacy of current antibiotics.

Low albumin level is more strongly associated with adverse outcomes and Staphylococcus aureus infection than hemoglobin A1C or smoking tobacco

Postsurgical deep musculoskeletal infections are a major clinical problem in Orthopaedic Surgery. A serum-based nomogram, which can objectively risk-stratify patients, and aid surgeons in delineating infection risk associated with orthopedic surgical interventions, would be immensely helpful. Here, we constructed a multi-parametric nomogram based on serum anti-Staphylococcus aureus antibody responses, patient characteristics including demographics and standard clinical tests. This nomogram was formally tested in a prospective cohort study comparing 303 hospitalized patients with culture-confirmed S. aureus infection compared with a cohort of 223 healthy screened preoperative patients. Serum anti-S. aureus antibody responses, standard of care clinical tests, and patient demographic data were utilized to perform multivariate logistic regression analysis to quantify the presence of infection and adverse outcome using odds ratios (OR) and to assess predictive ability via area under the ROC curve (AUC). At enrollment, high anti-S. aureus IgG titers were predictive of infection. Remarkably, low serum albumin was found to be significantly associated with infection (OR = 479.963, 95% CI 61.59 - 3740.33, p < 0.0001) and this finding was surprisingly higher than BMI or HbA1c-associations. Combining all risk factors in the nomogram yielded a diagnostic AUC of 0.949 for predicting S. aureus infection. Our results indicate that a serum-based multi-parametric nomogram can be useful in diagnosing S. aureus infections, and importantly, malnourishment is significantly associated with these infections.

Prevalence, Risk Factors and Microbiological Profile of Orthopaedic Surgical Site Infection in North-Eastern Peninsular Malaysia

Introduction

The devastating outcome of orthopaedic surgical site infections (SSI) are largely preventable if its risk factors, causative organisms and antimicrobial susceptibility patterns in the regional area are known.

Materials and methods

We conducted a retrospective study to address the lack of epidemiological and microbiological data on orthopaedic SSI in Malaysia. All the 80 patients diagnosed and treated for microbiologically proven orthopaedic SSIs in a tertiary hospital in Malaysia from April 2015 to March 2019 were included in a 1:2 case control study.

Results

The prevalence of SSI in clean and clean-contaminated surgeries was 1.243%, which is consistent with most of the studies worldwide, but is low compared to other studies done in Malaysia. The most common type of orthopaedics SSI were internal fixation infections (46.25%), superficial SSIs (25.2%) and Prosthetic joint infections (18.75%). Obesity and tobacco use were found to be significant risk factors of orthopaedic SSI. The most common perioperative prophylaxis used was IV cefuroxime. Majority of the cases (86.5%) received prolonged prophylactic antibiotics. The most common causative agent was Staphylococcus aureus (31.25%), followed by Pseudomonas aeruginosa (26.25%) and Enterobacter spp (7.5%). Methicillin-resistant Staphylococcus aureus (MRSA) accounted for 20% of the S. aureus infections. Up to 19.4% of the Gram-negative organisms are multidrug resistant. The higher rate of isolation of organisms resistant to the prophylactic antibiotics being used may be related to the prolonged use of prophylactic antibiotics, which exerted selective pressure for the acquisition of resistant organisms.

Conclusion

Despite its relatively low prevalence in our local institution and worldwide, the prevention of SSI in orthopaedic practice is crucial to avoid morbidity, mortality and high healthcare cost. This may be achieved by control of modifiable risk factors such as obesity and tobacco use, appropriate use of prophylactic antibiotics and implementation of good surgical and infection control practices.

Risk Factors Analysis of Surgical Infection Using Artificial Intelligence: A Single Center Study

Background: Surgical site infections (SSIs) have a major role in the evolution of medical care. Despite centuries of medical progress, the management of surgical infection remains a pressing concern. Nowadays, the SSIs continue to be an important factor able to increase the hospitalization duration, cost, and risk of death, in fact, the SSIs are a leading cause of morbidity and mortality in modern health care. Methods: A study based on statistical test and logistic regression for unveiling the association between SSIs and different risk factors was carried out. Successively, a predictive analysis of SSIs on the basis of risk factors was performed. Results: The obtained data demonstrated that the level of surgery contamination impacts significantly on the infection rate. In addition, data also reveals that the length of postoperative hospital stay increases the rate of surgical infections. Finally, the postoperative length of stay, surgery department and the antibiotic prophylaxis with 2 or more antibiotics are a significant predictor for the development of infection. Conclusions: The data report that the type of surgery department and antibiotic prophylaxis there are a statistically significant predictor of SSIs. Moreover, KNN model better handle the imbalanced dataset (48 infected and 3983 healthy), observing highest accuracy value.

Engineering Multifunctional Hydrogel-Integrated 3D Printed Bioactive Prosthetic Interfaces for Osteoporotic Osseointegration

3D printed porous titanium alloy implants is an advanced orthopedic material for joint replacement. However, the high risk of aseptic loosening and periprosthetic infection is difficult to avoid, and the declined autophagy of osteoporosis-derived bone marrow mesenchymal stem cells (OP-BMSCs) further severely impairs the osseointegration under the osteoporotic circumstance. It is thus becoming urgently significant to develop orthopedic materials with autophagy regulation and antibacterial bioactivity. In this regard, a novel class of multifunctional hydrogel-integrated 3D printed bioactive prosthetic interfaces is engineered for in situ osseointegration in osteoporosis. The hydrogel is fabricated from the dynamic crosslinking of synthetic polymers, natural polymers, and silver nanowires to deliver autophagy-regulated rapamycin. Therefore, the resultant soft material exhibits antibacterial ability, biocompatibility, degradability, conductive, self-healing, and stimuli-responsive abilities. In vitro experiments demonstrate that the hydrogel-integrated 3D printed bioactive prosthetic interfaces can restore the declined cellular activities of OP-BMSCs by upregulating the autophagy level and show excellent antibacterial activity against S. aureus and MRSA. More remarkably, the multifunctional 3D printed bioactive prosthetic interfaces significantly improve osseointegration and inhibit infection in osteoporotic environment in vivo. This study provides an efficient strategy to develop novel prosthetic interfaces to reduce complications after arthroplasty for patients with osteoporosis.

Mortality risk in patients with underweight or obesity with peripheral artery disease: a meta-analysis including 5,735,578 individuals

OBJECTIVES

The "obesity paradox" - in which patients with obesity exhibit superior survival than normal-weight counterparts - has been reported for several diseases. However, obesity is a well-known risk factor for cardiovascular disease, and whether the obesity paradox is present in peripheral artery disease (PAD) is unknown.

METHODS

A comprehensive search for studies that reported mortality in patients with PAD grouped by BMI identified 12 studies. We compared the survival of underweight patients with those who were not underweight, and patients with obesity against those without. Underweight was defined by a BMI value of <18.5 kg/m² in most studies and obesity by BMI ≥ 30 kg/m². Subgroup analyses were performed according to length of follow-up, presentation of PAD, and mode of revascularization. Meta-regression analyses were conducted, with covariates including age, sex, presence of coronary artery disease (CAD) and diabetes mellitus (DM).

RESULTS

The mortality risk of underweight patients with PAD was significantly higher compared to those who are not underweight (HR 1.72, 95% CI 1.38-2.14; I² = 84.2%). In contrast, the mortality risk of patients with obesity with PAD was significantly lower than those without (HR 0.78, 95% CI 0.62-0.97; I² = 89.8%). These findings remained consistent regardless of the presentation of PAD, revascularization, age, sex, or presence of CAD. The risk of death in the short-term of underweight patients (HR 1.50, 95% CI 0.47-4.72) and patients with obesity (HR 0.86, 95% CI 0.66-1.13) were not significantly different from their counterparts. The meta-regression showed that of the association between obesity and better survival was more pronounced in studies with a greater proportion of patients with concomitant CAD (regression coefficient -0.029, 95% CI -0.054 to -0.004).

CONCLUSIONS

In patients with PAD, mortality is higher among underweight patients and lower among patients with obesity. The mechanisms underlying the obesity paradox in patients with PAD remain to be elucidated, and further evidence is required to guide optimal weight control strategies in these patients.

Increasing but levelling out risk of revision due to infection after total hip arthroplasty: a study on 108,854 primary THAs in the Norwegian Arthroplasty Register from 2005 to 2019

Background and purpose - Focus on prevention, surveillance, and treatment of infection after total hip arthroplasty (THA) in the last decade has resulted in new knowledge and guidelines. Previous publications have suggested an increased incidence of surgical revisions due to infection after THA. We assessed whether there have been changes in the risk of revision due to deep infection after primary THAs reported to the Norwegian Arthroplasty Register (NAR) over the period 2005-2019.Patients and methods - Primary THAs reported to the NAR from January 1, 2005 to December 31, 2019 were included. Adjusted Cox regression analyses with the first revision due to deep infection after primary THA were performed. We investigated changes in the risk of revision as a function of time of primary THA. Time was stratified into 5-year periods. We studied the whole population of THAs, and the subgroups: all-cemented, all-uncemented, reverse hybrid (cemented cup), and hybrid THAs (cemented stem). In addition, we investigated factors that were associated with the risk of revision, and changes in the time span from primary THA to revision.Results - Of the 108,854 primary THAs that met the inclusion criteria, 1,365 (1.3%) were revised due to deep infection. The risk of revision due to infection, at any time after primary surgery, increased through the period studied. Compared with THAs implanted in 2005-2009, the relative risk of revision due to infection was 1.4 (95% CI 1.2-1.7) for 2010-2014, and 1.6 (1.1-1.9) for 2015-2019. We found an increased risk for all types of implant fixation. Compared to 2005-2009, for all THAs, the risk of revision due to infection 0-30 days postoperatively was 2.2 (1.8-2.8) for 2010-2014 and 2.3 (1.8-2.9) for 2015-2019, 31-90 days postoperatively 1.0 (0.7-1.6) for 2010-2014 and 1.6 (1.0-2.5) for 2015-2019, and finally 91 days-1 year postoperatively 1.1 (0.7-1.8) for 2010-2014 and 1.6 (1.0-2.6) for 2015-2019. From 1 to 5 years postoperatively, the risk of revision due to infection was similar to 2005-2009 for both the subsequent time periodsInterpretation - The risk of revision due to deep infection after THA increased throughout the period 2005-2019, but appears to have levelled out after 2010. The increase was mainly due to an increased risk of early revisions, and may partly have been caused by a change of practice rather than a change in the incidence of infection.

Preoperative decolonization and periprosthetic joint infections-A randomized controlled trial with 2-year follow-up

Preoperative decolonization, especially of Staphylococcus aureus carriers, has been proposed to reduce periprosthetic joint infections (PJI), but the evidence-based consensus is still lacking and data on long-term outcomes is scarce. In a previous randomized, single-blinded trial, decolonization produced no significant reduction of surgical site infections in overall elective orthopedic surgery at 3-month follow-up. A 2-year follow-up was then performed to specifically detect the impact of decolonization on delayed-onset PJI (3-24 months after surgery). Between November 2015 and September 2017, 613 of 1318 recruited patients underwent prosthetic surgery. Individuals were allocated into either the S. aureus carrier group (34%, 207 of 613 patients) or the noncarrier group (406 of 613 patients), according to nasal swab screening results. Both groups were then randomized into intervention and control arms. In the S. aureus group, the intervention consisted of daily chlorhexidine showers and application of mupirocin nasal ointment twice a day for 5 days before surgery. In noncarriers, only chlorhexidine showers were prescribed. Sample size calculation was based on the initial trial for overall and not for the prosthetic surgery group. No PJI was found at 2 years in either the carrier or in the noncarrier group. Therefore, no definite conclusion about the efficacy of preoperative decolonization to reduce PJI can be drawn. PJI proportions in this study were lower than described in the literature (mostly around 0.3%). Despite the insufficient sample size, this trial is the largest randomized trial on decolonization with a long-term follow-up, and results may be helpful for future meta-analyses.

Prospective Analysis of Hand Infection Rates in Elective Soft Tissue Procedures of the Hand: The Role of Preoperative Antibiotics

Background: The purpose of this study was to evaluate the efficacy of prophylactic antimicrobial prophylaxis in elective hand surgery in preventing postoperative infection. Methods: Between 2009 and 2012, we performed a multicenter trial in which patients undergoing elective hand surgeries were categorized into an antibiotic or control group depending on the center they were enrolled in. Surgical site infections were defined according to the Centers for Diseases Control and Prevention. Results: In total, 434 patients were included: 257 did not receive antibiotics (control) and 177 received antibiotics at a mean age of 61.0 years. In the control group, comorbidities were more common with 23.7% (61/257) in comparison to the antibiotics group with 14.1% (25/177). Only one surgical site infection in each group was identified. One wound was opened surgically, and an antimicrobial treatment was indicated in both cases. In addition, we observed four complications in the control group and three complications in the antibiotics group which required conservative management. No significant differences in the two cohorts in infection rate (0.006% vs 0.003%, χ² = 0.07, P > .05) and complication rate (2.8% vs 1.6%, χ² = 0.01, P > .05) were found. Conclusions: Our prospective multicenter trial showed no significant difference in infection rate in elective hand surgery whether antibiotics were administered preoperatively or not.

Effect of Postoperative Oral Antibiotics on Infections and Wound Healing Following Foot and Ankle Surgery

BACKGROUND

There is controversy regarding the effectiveness of postoperative antibiotics to prevent wound infection. Some surgeons still use a routine postoperative oral antibiotic regimen. The purpose of this study was to review a series of cases and document statistically any difference in infection rates and whether routine postoperative antibiotics in foot and ankle surgery are justified.

METHODS

A retrospective chart review of 649 patients was performed who underwent elective foot and ankle surgery. Six hundred thirty-one patient charts were included in the final analysis. Evaluated were patients who did and did not receive postoperative oral antibiotics in order to identify whether a difference in infection rate or wound healing occurred. The study also evaluated risk factors for developing infection following foot and ankle surgery.

RESULTS

The number of infections in patients receiving postoperative oral antibiotics was 6 (3%), while the number of infections in those who did not receive postoperative oral antibiotics was 10 (2%) (P = .597). The difference of deep versus superficial infections and delays in wound healing between the 2 groups was not statistically significant. Patients who developed infections were older and had a higher prevalence of hypertension, a history of neoplasm, and a greater American Society of Anesthesiologists Classification of Physical Health.

CONCLUSION

This study suggests that routine use of postoperative antibiotics in foot and ankle surgery does not affect wound complications or infection rates. Additionally, patients who are older and those with multiple medical problems may be at higher risk for developing postoperative infection following foot and ankle surgeries.

LEVEL OF EVIDENCE

Level III, retrospective comparative series.

Adhesin Protein Interaction of Staphylococcus Aureus Bacteria with Various Biomaterial Surfaces

The primary stage of adhesion during implant infection is dominated by interactions of the surface proteins of the bacteria with the substrate atoms. In the current work, molecular dynamics (MD) simulations have been utilized to investigate the mechanics of the associated adhesion forces of bacteria on different surfaces. The unfolding of these adhesion proteins is investigated in order to map these events to earlier experiments on bacterial de-adhesion (using single cell force spectroscopy) with real-life substrates (i.e., ultrahigh molecular weight polyethylene, hydroxyapatite, Ti alloy, and stainless steel). The adhesion of Staphylococcus aureus adhesin (i.e., SpA) is observed by altering their orientation on the silica substrate through MD simulations, followed by capturing unfolding events of three adhesins (SpA, ClfA, and SraP) of variable lengths possessing different secondary structures. The output long-range and short-range interaction forces and consequent visualization of changes in the secondary structure of protein segments are presented during the de-adhesion process. Simulation results are correlated with extracted short-range forces (using Poisson regression) from real-life bacterial de-adhesion experiments. Insights into such protein-substrate interactions may allow for engineering of biomaterials and designing of nonbiofouling surfaces.

Relationship between skin and urine colonization and surgical site infection in the proximal femur fracture: a prospective study

PURPOSE

Antibiotic prophylaxis is routinely used in the surgical management of proximal femur fractures. The role of bacterial colonization of the skin and urine in the development of deep surgical site infections (SSI) is yet to be elucidated. This study aimed to evaluate the role of previous skin and urine colonization in the development of deep SSI after a proximal femoral fracture surgery.

METHODS

We conducted a prospective observational study in 326 patients > 64 years old, who were scheduled to surgery. Cultures from skin samples of the surgical site and from urine were performed prior to the procedure, and cefazoline was administered as prophylaxis.

RESULTS

Skin microbiota was isolated in 233 (71.5%) cases; 8 (2.5%) samples were positive for other bacteria, and 85 (26%) were negative. Of 236 urine samples, 168 were negative or contaminated (71.2%), and 68 (28.8%) were positive, being 58/236 for Enterobacterales (24.6%). Acute deep SSI were diagnosed in nine out of 326 patients (2.7%), and two (22%) were infected by Gram-negative bacilli. Of the 9 cases, normal skin microbiota was isolated in 7 (78%), and the remaining two were negative. Seven cases had negative or contaminated urine cultures, and the one with E. coli did not correlate with SSI bacteria.

CONCLUSION

In our elderly hip fracture population, most patients harbored normal skin microbiota, and Enterobacterales urine cultures were positive in one-quarter of cases. There was no relationship between skin colonization, urine culture, and deep SSI. We therefore do not believe that our patients would benefit from modifying the current antibiotic prophylaxis.

The combination of multi-functional ingredients-loaded hydrogels and three-dimensional printed porous titanium alloys for infective bone defect treatment

Biomaterial with the dual-functions of bone regeneration and antibacterial is a novel therapy for infective bone defects. Three-dimensional (3D)-printed porous titanium (pTi) benefits bone ingrowth, but its microporous structure conducive to bacteria reproduction. Herein, a multifunctional hydrogel was prepared from dynamic supramolecular assembly of sodium tetraborate (Na2B4O7), polyvinyl alcohol (PVA), silver nanoparticles (AgNPs) and tetraethyl orthosilicate (TEOS), and composited with pTi as an implant system. The pTi scaffolds have ideal pore size and porosity matching with bone, while the supramolecular hydrogel endows pTi scaffolds with antibacterial and biological activity. In vitro assessments indicated the 3D composite implant was biocompatible, promoted bone marrow mesenchymal stem cells (BMSCs) proliferation and osteogenic differentiation, and inhibited bacteria, simultaneously. In vivo experiments further demonstrated that the implant showed effective antibacterial ability while promoting bone regeneration. Besides distal femur defect, the innovative scaffolds may also serve as an ideal biomaterial (e.g. dental implants) for other contaminated defects.

Improving surgical antibiotic prophylaxis adherence and reducing hospital readmissions: a bundle of interventions including health information technologies

OBJECTIVES

Infection following orthopaedic surgery is a feared complication and an indicator of the quality of the hospital. Surgical antibiotic prophylaxis (SAP) guidelines are not always properly followed. Our aim was to describe and evaluate the impact of a multidisciplinary intervention on antibiotic prophylaxis adherence to hospital guidelines and 30-day postoperative outcomes.

METHODS

The study was carried out from January to May 2016 and consisted of creating a multidisciplinary team, updating institutional guidelines and embedding the recommendations in the computerised physician order entry system which is linked to dose and renal function alerts, educational activities and pharmaceutical bedside care of patients in the orthopaedic department. A prospective pre-post study was carried out in accordance with the Declaration of Helsinki. The following information was recorded: patient and surgery characteristics, adherence to SAP guidelines, surgical site infections, length of hospital stay and rate of readmission 30 days after discharge. Statistical analyses were performed using SPSS 18.0.

RESULTS

Eighty three orthopaedic patients of mean±SD age 68.2±17.0 years (44.6% male, 40 in the pre-intervention group and 43 in the intervention group) were included. Cefazolin was the recommended and most commonly administered antibiotic agent. In the intervention group, an improvement in global adherence to guidelines was achieved (76.7% vs 89.9%; p=0.039): antibiotic duration (75.0% vs 97.7%), correct dosage post-surgery (55.0% vs 76.7%), timing of administration (57.5% vs 72.1%), antibiotic pre-surgery prescription (92.5% vs 97.7%). Three surgical site infections were detected in the pre-intervention group and none in the intervention group (p>0.05). Length of hospital stay was reduced by 1 day and readmission decreased by 15% (p=0.038).

CONCLUSIONS

SAP is used in daily practice in most orthopaedic patients. The implementation of a multidisciplinary programme based on health technology improved the adherence to guidelines and appeared to reduce the readmission rate.

Osteomyelitis: Recent advances in pathophysiology and therapeutic strategies

This review article summarizes the recent advances in pathogenic mechanisms and novel therapeutic strategies for osteomyelitis, covering both periprosthetic joint infections and fracture-associated bone infections. A better understanding of the pathophysiology including the mechanisms for biofilm formation has led to new therapeutic strategies for this devastating disease. Research on novel local delivery materials with appropriate mechanical properties, lower exothermicity, controlled release of antibiotics, and absorbable scaffolding for bone regeneration is progressing rapidly. Emerging strategies for prevention, early diagnosis of low-grade infections, and innovative treatments of osteomyelitis such as biofilm disruptors and immunotherapy are highlighted in this review.

Adhesion force of staphylococcus aureus on various biomaterial surfaces

Staphylococcus comprises of more than half of all pathogens in orthopedic implant infections and they can cause major bone infection which can result in destruction of joint and bone. In the current study, adhesion force of bacteria on the surface of various biomaterial surfaces is measured using atomic force microscope (AFM). Staphylococcus aureus was immobilized on an AFM tipless cantilever as a force probe to measure the adhesion force between bacteria and biomaterials (viz. ultra-high molecular weight poly ethylene (UHMWPE), stainless steel (SS), Ti-6Al-4V alloy, hydroxyapatite (HA)). At the contact time of 10s, UHMWPE shows weak adhesion force (~4nN) whereas SS showed strong adhesion force (~15nN) due to their surface energy and surface roughness. Bacterial retention and viability experiment (3M™ petrifilm test, agar plate) dictates that hydroxyapatite shows the lowest vaibility of bacteria, whereas lowest bacterial retention is observed on UHMWPE surface. Similar results were obtained from live/dead staining test, where HA shows 65% viability, whereas on UHMWPE, SS and Ti-6Al-4V, the bacterial viability is 78%, 94% and 97%, respectively. Lower adhesion forces, constrained pull-off distance (of bacterial) and high antibacterial resistance of bioactive-HA makes it a potential biomaterial for bone-replacement arthroplasty.

Time trends in the aetiology of prosthetic joint infections: a multicentre cohort study

It is important to know the spectrum of the microbial aetiology of prosthetic joint infections (PJIs) to guide empiric treatment and establish antimicrobial prophylaxis in joint replacements. There are no available data based on large contemporary patient cohorts. We sought to characterize the causative pathogens of PJIs and to evaluate trends in the microbial aetiology. We hypothesized that the frequency of antimicrobial-resistant organisms in PJIs has increased in the recent years. We performed a cohort study in 19 hospitals in Spain, from 2003 to 2012. For each 2-year period (2003-2004 to 2011-2012), the incidence of microorganisms causing PJIs and multidrug-resistant bacteria was assessed. Temporal trends over the study period were evaluated. We included 2524 consecutive adult patients with a diagnosis of PJI. A microbiological diagnosis was obtained for 2288 cases (90.6%). Staphylococci were the most common cause of infection (1492, 65.2%). However, a statistically significant rising linear trend was observed for the proportion of infections caused by Gram-negative bacilli, mainly due to the increase in the last 2-year period (25% in 2003-2004, 33.3% in 2011-2012; p 0.024 for trend). No particular species contributed disproportionally to this overall increase. The percentage of multidrug-resistant bacteria PJIs increased from 9.3% in 2003-2004 to 15.8% in 2011-2012 (p 0.008), mainly because of the significant rise in multidrug-resistant Gram-negative bacilli (from 5.3% in 2003-2004 to 8.2% in 2011-2012; p 0.032). The observed trends have important implications for the management of PJIs and prophylaxis in joint replacements.

An Evaluation of Surgical Prophylaxis Procedures in Turkey: A Multi-Center Point Prevalence Study

OBJECTIVE

The purpose of this study was to evaluate compliance with guidelines in surgical prophylaxis (SP) procedures in Turkey.

MATERIALS AND METHODS

A point prevalence study involving 4 university, 5 education and research and 7 public hospitals was performed assessing compliance with guidelines for antibiotic use in SP. Compliance was based on the "Clinical Practice Guidelines for Antimicrobial Surgery (CPGAS) 2013" guideline.

RESULTS

Sixteen centers were included in the study, with 166 operations performed at these being evaluated. Parenteral antibiotic for SP was applied in 161 (96.9%) of these. Type of antibiotic was inappropriate in 66 (40.9%) cases and duration of use in 47 (29.1%). The main antibiotics used inappropriately in SP were ceftriaxone, glycopeptides and aminoglycosides. No significant difference was observed between secondary and tertiary hospitals in terms of inappropriate selection. Duration of prophylaxis was also incompatible with guideline recommendations in approximately half of surgical procedures performed in both secondary and tertiary hospitals, however statistical significance was observed between institutions in favor of tertiary hospitals.

CONCLUSION

Antibiotics are to a considerable extent used in a manner incompatible with guidelines even in tertiary hospitals in Turkey. It must not be forgotten that several pre-, intra- and postoperative factors can be involved in the development of surgical site infections (SSI), and antibiotics are not the only option available for preventing these. A significant improvement can be achieved in prophylaxis with close observation, educational activities, collaboration with the surgical team and increasing compliance with guidelines. All health institutions must establish and apply their own SP consensus accompanied by the guidelines in order to achieve success in SP.

Multi-disciplinary antimicrobial strategies for improving orthopaedic implants to prevent prosthetic joint infections in hip and knee

Like any foreign object, orthopaedic implants are susceptible to infection when introduced into the human body. Without additional preventative measures, the absolute number of annual prosthetic joint infections will continue to rise, and may exceed the capacity of health care systems in the near future. Bacteria are difficult to eradicate from synovial joints due to their exceptionally diverse taxonomy, complex mechanistic attachment capabilities, and tendency to evolve antibiotic resistance. When a primary orthopaedic implant fails from prosthetic joint infection, surgeons are generally challenged by limited options for intervention. In this review, we highlight the etiology and taxonomic groupings of bacteria known to cause prosthetic joint infections, and examine their key mechanisms of attachment. We propose that antimicrobial strategies should focus on the most harmful bacteria taxa within the context of occurrence, taxonomic diversity, adhesion mechanisms, and implant design. Patient-specific identification of organisms that cause prosthetic joint infections will permit assessment of their biological vulnerabilities. The latter can be targeted using a range of antimicrobial techniques that exploit different colonization mechanisms including implant surface attachment, biofilm formation, and/or hematogenous recruitment. We anticipate that customized strategies for each patient, joint, and prosthetic component will be most effective at reducing prosthetic joint infections, including those caused by antibiotic-resistant and polymicrobial bacteria.

Prophylactic antibiotics in elective hip and knee arthroplasty: an analysis of organisms reported to cause infections and National survey of clinical practice

Objectives

We wanted to investigate regional variations in the organisms reported to be causing peri-prosthetic infections and to report on prophylaxis regimens currently in use across England.

Methods

Analysis of data routinely collected by Public Health England’s (PHE) national surgical site infection database on elective primary hip and knee arthroplasty procedures between April 2010 and March 2013 to investigate regional variations in causative organisms. A separate national survey of 145 hospital Trusts (groups of hospitals under local management) in England routinely performing primary hip and/or knee arthroplasty was carried out by standard email questionnaire.

Results

Analysis of 189 858 elective primary hip and knee arthroplasty procedures and 1116 surgical site infections found statistically significant variations for some causative organism between regions. There was a 100% response rate to the prophylaxis questionnaire that showed substantial variation between individual trust guidelines. A number of regimens currently in use are inconsistent with the best available evidence.

Conclusions

The approach towards antibiotic prophylaxis in elective arthroplasty nationwide reveals substantial variation without clear justification. Only seven causative organisms are responsible for 89% of infections affecting primary hip and knee arthroplasty, which cannot justify such widespread variation between prophylactic antibiotic policies.

Cite this article: Bone Joint Res 2015;4:181–189.