Intraoperative contamination influences wound discharge and periprosthetic infection

Are iodophor-impregnated drapes associated with lower intraoperative contamination compared to no adhesive drape?: A protocol for systematic review and meta analysis

BACKGROUND

Surgical site infection (SSI) is one of the most frightening complications after surgery. Adhesive drapes (AD) are widely used as an infection prevention tool. They can be non-impregnated or iodophor-impregnated, although non-impregnated are less used as they might be related to higher number of infections. One of the most common ways to study their efficacy is by analyzing the intraoperative contamination, which is a useful primary endpoint as it does not need follow-up and it has been strongly associated with infections. Therefore, we believe a systematic review (SR) and meta-analysis is needed to determine which is the literature available about this topic and to explore their results.

METHODS

All randomized controlled trials (RCT) published since 1984 through to January 15, 2023 will be included. Non-human and experimental studies will be excluded. We will only include studies written in English. We will conduct searches in the following electronic databases: MEDLINE (via PubMed), SCOPUS and Web Of Science. The protocol of the SR was registered in PROSPERO under the number CRD42023391651 and was written according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocol guidelines.

DISCUSSION

The evidence regarding the benefits of using iodophor-impregnated adhesive drapes (IIAD) is scarce. Therefore, this SR and meta-analysis is required to determine if they are related with a lower intraoperative contamination incidence, compared to no AD.

Do Cultures Obtained During Primary THA Predict the Likelihood of Revision?

BACKGROUND

There can be unexpectedly positive culture results during elective hip arthroplasty, but the degree to which these are associated with an increased risk of subsequent premature revision is not known.

QUESTION/PURPOSE

Are unexpectedly positive culture results obtained during elective THA associated with an increased likelihood of revision within 5 years of the procedure?

METHODS

Between March 2007 and March 2011, the hip unit at our institution performed elective primary THA in 829 patients. We systematically collected three samples in 52% (428 of 829) of the interventions. Of those, 26 patients were excluded because of sampling errors; 94% (402 of 428) had samples that were collected systematically and were eligible for the study. We only considered one hip randomly in bilateral procedures (4% [15 of 428]); patients presenting with acute (< 3 months) periprosthetic joint infection undergoing open debridement (4% [16 of 402]) and patients who died before 5 years of follow-up (2% [seven of 402]) were excluded from the study, leaving 91% (364 of 402) eligible for analysis in this retrospective study of a previous prospective trial. No patient included in the final analysis was lost to follow-up within 5 years from the index surgery. The patient group consisted of 52% (188 of 364) women, with a mean ± SD age of 64.8 ± 13.9 years.

RESULTS

Positives culture results were associated with a higher risk of revision within 5 years of the index surgery. The proportion of revision surgery was higher in the group with positive culture results than in those with negative results (10% [eight of 77] versus 2% [seven of 290]; p = 0.01). The difference was mainly attributable to a higher proportion of aseptic loosening in those with positive culture results than in those with negative results (8% [six of 74] versus 1% [four of 290]; p = 0.01). After a multivariable analysis, the only independent variable associated with 5-year revision surgery was the presence of positive results during THA (odds ratio 4.9 [95% confidence interval 1.72 to 13.99]).

CONCLUSION

Our findings suggest that bacterial contamination during THA is associated with an increased likelihood of early revision. This higher risk of revision is mainly because of presumed aseptic loosening; thus, efforts should focus on the need to rule out infection. These results not only open new questions that should be answered in new prospective and well-designed studies, but also may help to better select patients to obtain a more favorable outcome after THA.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Impact of salivary contamination during implant placement with different surface characteristics in native and augmented bone: An in vivo study in sheep calvaria model

OBJECTIVES

The aim of this study was to evaluate whether salivary contamination during placement of implants with different surface characteristics affects osseointegration in native and in augmented bone areas.

MATERIALS AND METHODS

Forty eight implants with machined surface (MS) and 48 implants with moderately rough surface (RS) were tested in the calvaria of 12 sheep. At the first surgery, 64 bony critical defects were randomly created and were subsequently augmented with two materials (autogenous or bovine bone). After 5 weeks of graft healing, 8 implants were placed per sheep, in native bone and in the centre of the augmented defects. Forty eight implants were soaked with saliva before placement (contaminated group [CG]), while 48 implants were not (non-contaminated group [NCG]). Five weeks after implant placement, bone-to-implant contact (BIC) and bone material area fraction occupancy (BMAFO) were calculated histomorphometrically.

RESULTS

Saliva contamination showed a significant negative effect (p = .000) on BIC, especially in augmented areas. RS showed significant positive effect on BIC, compared to MS (p = .000), while there were no significant differences for different bone conditions (p = .103). For BMAFO, the contamination showed a significantly negative affect (p = .000), while there were no significant differences for surface characteristics (p = .322) and for bone condition (p = .538).

CONCLUSION

Saliva contamination during dental implant placement has a negative effect on osseointegration in augmented areas. Moderately rough surface has a possible advantage in the aspect of initial bone to implant contact. However, it seems to be advisable to avoid saliva contamination especially for implants placed in augmented bone areas.

[Possible routes of infection in hip replacement]

OBJECTIVE

To evaluate the probability of direct inoculation of pathogens into the bone bed by surgical instruments and implants.

MATERIAL AND METHODS

The study included 22 patients who underwent surgery at the Vreden National Medical Research Center of Traumatology and Orthopedics. Mean age was 73.3±3.7 years. These patients underwent total hip replacement. Intraoperative skin scrapings within the wound edge were made. Pressure on the scalpel was applied in two fashions. In 10 cases, scraping was performed by minimally pressure on the skin (superficial contact). In 12 cases, scalpel was pressed with force (skin deformation to a depth of 3-4 mm). Next, microbiological analysis of scrapings was performed.

RESULTS

There was no growth of microorganisms in samples obtained by minimal pressure on the scalpel. Analysis of 12 scrapings in the second group (tight contact simulating damage to the skin with surgical instruments) revealed growth of microflora in all cases.

CONCLUSION

Contact of cutters, rasps and implants with skin can be a mechanism for direct inoculation of pathogens into the bone tissue and potentially cause periprosthetic infection.

Reduction in Operating Room Airborne Particle Burden and Time-Dependent Contamination of Sterile Instrument Trays With the Use of a Novel Air Filtration System

Introduction

Postoperative infections represent a substantial burden to patients and healthcare systems. To improve patient care and reduce healthcare expenditures, interventions to reduce surgical infections must be employed. The crystalline C-band ultraviolet (UV-C) air filtration technology (Aerobiotix Inc., Miamisburg, OH, USA) has been designed to reduce airborne bioburden through high-quality filtration and germicidal irradiation. The purpose of this study was to assess the ability of a novel UV-C air filtration device to reduce airborne particle counts and contamination of surgical instrument trays in an operating room (OR) setting.

Materials and methods

Thirty sterile instrument trays were opened in a positive-air-flow OR. The trays were randomly assigned to one of two groups (UV-C or control, n=15 per group). In the UV-C group, the UV-C filtration device was used and in the control, it was not. All trays were opened with the use of a sterile technique and left exposed in the OR for four hours. Air was sampled by a particle counter to measure the numbers of 5µm and 10µm particles. Culture specimens were obtained from the trays to assess for bacterial contamination. Outcome data were collected at 30-minute intervals for the duration of the four-hour study period.

Results

Use of the UV-C device resulted in statistically significant reductions in the numbers of 5µm (average of 64.9% reduction when compared with the control, p<0.001) and 10µm (average of 65.7% reduction when compared with the control, p<0.001)-sized particles detectable in the OR. There was no significant difference in the overall rates of contamination (33.3% in the control group vs. 26.7% in the UV-C group, p=1.0) or the time to contamination (mean survival of 114 minutes in the control group vs. 105 minutes in the UV-C group, p=0.72) of surgical instrument trays with the use of the UV-C device.

Conclusions

The results demonstrate that the UV-C filtration device can successfully reduce airborne bioburden in standard ORs, suggesting that it may have the potential to reduce the risk for wound and hardware infections. Further clinical trials are necessary to better determine the effect of this air filtration system on postoperative infection rates.

An intraoperative assessment of bacterial contamination on surgical helmets and gloves during arthroplasty surgeries

INTRODUCTION

Infection is a devasting complication after primary and revision arthroplasty. Therefore, identifying potential sources of infection can help to reduce infection rates. The aim of this study was to identify the impact and potential risk of contamination for glows and surgical helmets during arthroplasty procedures.

METHODS

Surveillance cultures were used to detect contamination of the glow interface during the surgery and the surgical helmets immediately at the end of the surgery. The cultures were taken from 49 arthroplasty procedures from the surgeon as well as the assisting surgeon.

RESULTS

In total, 196 cultures were taken. 31 (15.8%) of them showed a contamination. 12 (13.5%) of 98 cultures taken from the surgical helmets were positive, while 18 (18.3%) of 96 cultures taken from the gloves showed a contamination.

DISCUSSION

The study showed that during arthroplasty procedures, surgical helmets and gloves were frequently contaminated with bacteria. In 20 of 49 (40.8%) arthroplasty surgeries, either the surgical helmet or the gloves showed a contamination. Surgeons should be aware that they might be a source for infection during arthroplasty surgeries.

Intraoperative Bacterial Contamination and Activity of Different Antimicrobial Prophylaxis Regimens in Primary Knee and Hip Replacement

Surgical antimicrobial prophylaxis (SAP) is important for the prevention of prosthetic joint infections (PJIs) and must be effective against the microorganisms most likely to contaminate the surgical site. Our aim was to compare different SAP regimens (cefazolin, cefuroxime, or vancomycin, alone or combined with gentamicin) in patients undergoing total knee (TKA) and hip (THA) arthroplasty. In this preclinical exploratory analysis, we analyzed the results of intraoperative sample cultures, the ratio of plasma antibiotic levels to the minimum inhibitory concentrations (MICs) for bacteria isolated at the surgical wound and ATCC strains, and serum bactericidal titers (SBT) against the same microorganisms. A total of 132 surgical procedures (68 TKA, 64 THA) in 128 patients were included. Cultures were positive in 57 (43.2%) procedures (mostly for coagulase-negative staphylococci and Cutibacterium spp.); the rate was lower in the group of patients receiving combination SAP (adjusted OR 0.475, CI95% 0.229-0.987). The SAP regimens evaluated achieved plasma levels above the MICs in almost all of intraoperative isolates (93/94, 98.9%) and showed bactericidal activity against all of them (SBT range 1:8-1:1024), although SBTs were higher in patients receiving cefazolin and gentamicin-containing regimens. The potential clinical relevance of these findings in the prevention of PJIs remains to be determined.

Impact of salivary contamination during placement of implants with simultaneous bony augmentation in iliac bone in sheep

Our aim was to investigate the possible impact of contamination with saliva on osseointegration during placement of implants with simultaneous bone augmentation. Six hemispheric shape bone defects (8mm in diameter×4mm deep) were prepared in each iliac bone of six sheep. A dental implant (2.9mm in diameter×10mm long) was placed in the centre of each defect, and then pairs of defects were filled with one of the following bone augmentation materials: autogenous bone, autogenous bone plus bovine bone, or resorbable biphasic ceramic bone substitute. One site in each augmentation group was impregnated with saliva (contaminated group), while the other was not (non-contaminated group). Bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) within implant threads were measured after a healing period of five weeks, both in respect of the implant inserted in the augmented bone and in that inserted in the residual bone. Overall results showed that there was a significant difference between the contaminated and non-contaminated group for BIC in the augmented implant (p=0.028), while there were no significant differences in the implant in residual bone (p=0.722). For BAFO, there were no significant differences between the contaminated and non-contaminated groups among the different augmentation materials. The results showed that contamination with saliva during placement of an implant with simultaneous bone augmentation had a serious deleterious effect on osseointegration of the aspect of the implant within the augmented defect. Contamination with saliva during placement of an implant with simultaneous bone augmentation should therefore be avoided.

Influence of a visible-light continuous environmental disinfection system on microbial contamination and surgical site infections in an orthopedic operating room

BACKGROUND

A growing body of research has demonstrated that manual cleaning and disinfection of the operating room (OR) is suboptimal. Residual environmental contamination may pose an infection risk to the surgical wound. This study evaluates the impact of a visible-light continuous environmental disinfection (CED) system on microbial surface contamination and surgical site infections (SSI) in an OR.

METHODS

Samples from 25 surfaces within 2 contiguous ORs sharing an air supply were obtained after manual cleaning on multiple days before and after a visible-light CED system installation in 1 of the ORs. Samples were incubated and enumerated as total colony-forming units. SSIs in both ORs, and a distant OR, were tracked for 1 year prior to and 1 year after the visible-light CED system installation.

RESULTS

There was an 81% (P = .017) and 49% (P = .015) reduction in total colony-forming units after the visible-light CED system installation in the OR in which the system was installed, and in the contiguous OR, respectively. In the OR with the visible-light CED system, SSIs decreased from 1.4% in the year prior to installation to 0.4% following installation (P = .029).

CONCLUSIONS

A visible-light CED system, used in conjunction with manual cleaning, resulted in significant reductions in both microbial surface contamination and SSIs in the OR.

Perioperative Contamination of Orthopaedic Polyethylene Implants, Targeting Devices and Arthroscopes. Experts' Decision Tree and Literature Review

Introduction Sterility errors during orthopaedic procedures can be stressful for the surgeon or scrub nurse and lead to devastating infectious complications and liability issues. This paper aims to review orthopaedic surgeon practices and propose possible attitudes to adopt.

Methods Out of 1023 questionnaires sent, 170 orthopaedic surgeons answered a Volunteer Feedback Template (multiple-choice test) by SurveyMonkey® (San Mateo, CA, USA) anonymously. The survey questioned surgeon's response to a sterility mistake during a standard total knee joint replacement, trauma surgery and arthroscopic procedure. Those “sterility mistake” situations occurred when there was contamination of 1) a sterile polyethylene (PE) 2) a sterile targeting device, and 3) an arthroscope.

Results When the definitive PE is contaminated, and if a new definitive PE will only be available 2 hours later, 52% of surgeons would wait for the new definitive PE (p<0.001). In the same situation, if a new PE will only be available in 4 hours, the results showed a significant difference favoring two other options: ”putting a definitive PE one size smaller or bigger with balance adjustment” (31%); and “leaving the provisional PE in the joint, closing the wound and re-operating the patient in the coming days when the definitive PE arrives” (29%) (p<0.001). When the new PE is only available 24 hours later results were 34% and 31%, respectively (p<0.001). In the case of a surgical procedure for a classic intertrochanteric fracture, if the carbon fiber targeting device is contaminated, most surgeons (50%) chose to put the nail without the targeting device and finish the surgery (p<0.001). When the arthroscope is desterilized, 39% of participants would wait until the arthroscope has been sterilized again (approximately 2 hours), while 24% would use another procedure (p<0.001). Sixty-two percent of surgeons would adapt their strategy. No clear trend could be identified in terms of antibiotic treatment following a sterility error.

Conclusions There are no established guidelines on how to deal with sterility breaches during surgery and on the antibiotic strategy following the prolonged surgical time resulting from the delay for a new implant. The most common course of action chosen by participating surgeons is detailed in our expert decision tree - if another sterile component is not available within 2 hours - : insertion of another PE size, rescheduling the operation, adapting the surgical technique (for trauma procedures), or soaking the arthroscope in disinfectant solution. As instances of contamination cannot be avoided, it is recommended to have a minimum of two copies of sterile PE implants, arthroscopes or targeting devices readily available before surgery begins-.

The Impact of Supplemental Intraoperative Air Decontamination on the Outcome of Total Joint Arthroplasty: A Pilot Analysis

BACKGROUND

During the early era of arthroplasty, the concept of ultraclean operating room (OR) was introduced based on the principle that the number of airborne particles in the OR directly influences incidence of device-related infections. The hypothesis of this pilot study was that use of an innovative UV-C air decontamination technology would lead to a reduction in the incidence of periprosthetic joint infection (PJI) following total joint arthroplasty.

METHODS

A retrospective, observational, surveillance study was conducted with a consecutive series of patients who underwent total joint arthroplasty (n = 496) between January 2016 and August 2017. All perioperative and postoperative care protocols were identical for both groups, only study variable was that in 231 arthroplasty patients (OR B), an innovative supplemental UV-C air decontamination technology was used, whereas in the remaining 265 patients, arthroplasty was performed with standard turbulent HVAC (OR A).

RESULTS

There was no significant difference between patient groups regarding age, body mass index, diabetes diagnosis, smoking status, length of surgery, or revision status. The rate of PJI was documented to be 1.9% in the turbulent air group, and no infections were documented in the cohorts operated under UV-C air decontamination, which was statistically significant (P < .044).

CONCLUSION

While PJI is multifactorial in nature, the present retrospective pilot study suggests that use of an intraoperative supplemental air decontamination significantly reduced the overall risk of PJI. The findings of this study are encouraging and should be examined in a larger-scale, prospective, multicenter study.

Preventing infection in shoulder surgery

Although rare, infection after shoulder surgery can represent a devastating complication. Infection can negatively affect clinical outcomes, and eradication often requires a protracted treatment course. Staphylococcus aureus, Staphylococcus epidermidis, and Cutibacterium acnes are among the most frequently isolated pathogens. Perioperative measures can be implemented to reduce infection risk. Here we review various perioperative practices and their efficacy at reducing infection after shoulder surgery.

Environment of care: Is it time to reassess microbial contamination of the operating room air as a risk factor for surgical site infection in total joint arthroplasty?

In the modern operating room (OR), traditional surgical mask, frequent air exchanges, and architectural barriers are viewed as effective in reducing airborne microbial populations. Intraoperative sampling of airborne particulates is rarely performed in the OR because of technical difficulties associated with sampling methodologies and a common belief that airborne contamination is infrequently associated with surgical site infections (SSIs). Recent studies suggest that viable airborne particulates are readily disseminated throughout the OR, placing patients at risk for postoperative SSI. In 2017, virtually all surgical disciplines are engaged in the implantation of selective biomedical devices, and these implants have been documented to be at high risk for intraoperative contamination. Approximately 1.2 million arthroplasties are performed annually in the United States, and that number is expected to increase to 3.8 million by the year 2030. The incidence of periprosthetic joint infection is perceived to be low (<2.5%); however, the personal and fiscal morbidity is significant. Although the pharmaceutic and computer industries enforce stringent air quality standards on their manufacturing processes, there is currently no U.S. standard for acceptable air quality within the OR environment. This review documents the contribution of air contamination to the etiology of periprosthetic joint infection, and evidence for selective innovative strategies to reduce the risk of intraoperative microbial aerosols.

Effects of Bacterial Contamination on Dental Implants During Surgery: A Systematic Review

INTRODUCTION

Contamination during surgery negatively influences the prognosis of orthopaedic implants; however, it has not been proven whether contamination influences the success of dental implant treatment. The aim of the systematic review was to investigate if there exists evidence in the literature whether contamination of dental implants during surgery affects osseointegration and clinical success.

MATERIALS AND METHODS

Four data bases were used for the literature search. Primary studies and reviews regarding both clinical and preclinical research were eligible. Rating of the summarized quality of the evidence was performed.

RESULTS

Five preclinical studies were included. Because of the estimated high risk of bias in all included studies and extensive differences in study design between the included studies, meta-analysis was not performed and no reliable aggregated data could be extracted.

CONCLUSIONS

It is suggested that the scientific evidence with regard to the current topic is insufficient. Further controlled studies are warranted.

Iodine-impregnated incision drape and bacterial recolonization in simulated total knee arthroplasty

Background and purpose - Iodine-impregnated incision drapes (IIIDs) are used to prevent surgical site infection (SSI). However, there is some evidence to suggest a potential increase in SSI risk as a result of IIID use, possibly from promotion of skin recolonization. A greater number of viable bacteria in the surgical field of an arthroplasty, and surgery in general, may increase the infection risk. We investigated whether IIID use increases bacterial recolonization compared to no drape use under conditions of simulated total knee arthroplasty (TKA). Methods - 20 patients scheduled for TKA were recruited. Each patient had 1 knee randomized for draping with IIID, while the contralateral knee was left bare. The patients thus served as their own control. The operating room conditions and perioperative procedures of a TKA were simulated. Cylinder samples were collected from the skin of each knee prior to disinfection, and again on 2 occasions after skin preparation-75 min apart. Quantities of bacteria were estimated using a spread plate technique under aerobic conditions. Results - We found similar quantities of bacteria on the intervention and control knees immediately after skin disinfection and after 75 min of simulated surgery. These quantities had not increased at the end of surgery when compared to baseline, so no recolonization was detected on the draped knees or on the bare knees. Interpretation - The use of IIIDs did not increase bacterial recolonization in simulated TKA. This study does not support the hypothesis that IIIDs promote bacterial recolonization and postoperative infection risk.

Etiology of bone and joint infections: a case series of 363 consecutive patients from an orthopaedic infection unit

BACKGROUND

Bone and joint infections remain a clinical challenge with potentially serious consequences. Nevertheless there is a lack of studies with strict criteria for diagnosis and etiology. The primary aim of this study was to determine the causative agents in orthopaedic infections using strict diagnostic criteria for infection and etiology. The secondary aim was to assess the timing of post-operative infections in relation to pathogens and to compare causative bacteria in different parts of the body.

METHODS

A retrospective registry study of 363 consecutive cases of bone and joint infections was performed. Microbiological data on sampling and culture results were registered.

RESULTS

Staphylococcus aureus dominated in both operated (45%) and non-operated (44%) patients, followed in frequency by coagulase-negative staphylococci (CoNS) in operated patients (11%) and beta-haemolytic streptococci in non-operated patients (16%) (p < 0.001). There were no polymicrobial infections in non-surgical cases (p < 0.001). For operated patients, Gram-negative bacilli were observed in 6%, almost exclusively isolated from the lower extremity. Propionibacterium spp. was the most common finding after spinal surgery. In 90/363 (25%), the agent responsible for the infection could not be defined according to the strict criteria used.

CONCLUSION

S. aureus dominated as etiological agent in all bone and joint infections, including operated patient given peri-operative prophylaxis. Improved timing of antibiotic prophylaxis seen after the introduction of the Swedish national project PRISS may have changed this. The number of infections with uncertain etiology was high, stressing the importance of more studies on diagnostics, as well as strict diagnostic algorithms.

The Gown-glove Interface Is a Source of Contamination: A Comparative Study

BACKGROUND

The original Charnley-type negative-pressure body exhaust suit reduced infection rates in randomized trials of total joint arthroplasty (TJA) decades ago. However, modern positive-pressure surgical helmet systems have not shown similar benefit, and several recent studies have raised the question of whether these gowning systems result in increased wound contamination and infections. The gown-glove interface may be one source of particle contamination.

QUESTIONS/PURPOSES

The purpose of this study was to compare particle contamination at the gown-glove interface in several modern surgical helmet systems and conventional surgical gowns.

METHODS

A 5-μm fluorescent powder was evenly applied to both hands to the level of the wrist flexion crease. After gowning in the standard fashion, the acting surgeon performed a 20-minute simulated TJA protocol. Each of the five gowning systems was run through five trials. The amount of gown contamination at the gown-glove interface then was measured by three observers under ultraviolet light using a grading scale from 0 (no contamination) to 4 (gross contamination). Statistical analysis was carried out with Minitab 15. Friedman's test was used to compare the levels of contamination across trials for each gown and the Mann-Whitney test was used post hoc to perform a pairwise comparison of each gown.

RESULTS

All gown-glove interfaces showed some contamination. Friedman's test showed that there was a significant difference in contamination between gowns (p = 0.029). The Stryker T5 Zipper Toga system showed more contamination than the other gowns. The median contamination score and range for each gowning setup was 1.8 (range, 1-4; conventional Kimberly-Clark MicroCool gown without helmet), 4 (range, 3-4; Stryker T5 Zipper Toga), 3.6 (range, 0-4; Stryker helmet with conventional gown), 1.6 (range, 0-2; Stryker Flyte Toga), and 3.0 (range, 2-3; DePuy Toga). A Mann-Whitney test found no difference among any of the gowns except for the Stryker T5 Zipper Toga, which showed more contamination compared directly with each of the other four gowns (p < 0.001 for each gown-to-gown comparison).

CONCLUSIONS

Particle contamination occurs at the gown-glove interface in most commonly used positive-pressure surgical helmet systems. The Stryker T5 Zipper Toga exhibited more contamination than each of the other gowning systems.

CLINICAL RELEVANCE

The gown-glove interface is prone to particle contamination and all surgeons should be aware of this area as a potential source of surgical site infection. Although future studies are needed to clarify the link between particle contamination through this route and clinical infection, surgeons should consider using gowning systems that minimize the migration of fomites through the gown-glove interface.

Sequence types of Staphylococcus epidermidis associated with prosthetic joint infections are not present in the laminar airflow during prosthetic joint surgery

Molecular characterization of Staphylococcus epidermidis isolates from prosthetic joint infections (PJIs) has demonstrated a predominance of healthcare-associated multi-drug resistant sequence types (ST2 and ST215). How, and when, patients acquire these nosocomial STs is not known. The aim was to investigate if sequence types of S. epidermidis associated with PJIs are found in the air during prosthetic joint surgery. Air sampling was undertaken during 17 hip/knee arthroplasties performed in operating theaters equipped with mobile laminar airflow units in a 500-bed hospital in central Sweden. Species identification was performed using MALDI-TOF MS and 16S rRNA gene analysis. Isolates identified as S. epidermidis were further characterized by MLST and antibiotic susceptibility testing. Seven hundred and thirty-five isolates were available for species identification. Micrococcus spp. (n = 303) and coagulase-negative staphylococci (n = 217) constituted the majority of the isolates. Thirty-two isolates of S. epidermidis were found. S. epidermidis isolates demonstrated a high level of allelic diversity with 18 different sequence types, but neither ST2 nor ST215 was found. Commensals with low pathogenic potential dominated among the airborne microorganisms in the operating field during prosthetic joint surgery. Nosocomial sequence types of S. epidermidis associated with PJIs were not found, and other routes of inoculation are therefore of interest in future studies.

Staphylococcus epidermidis originating from titanium implants infects surrounding tissue and immune cells

Infection is a major cause of failure of inserted or implanted biomedical devices (biomaterials). During surgery, bacteria may adhere to the implant, initiating biofilm formation. Bacteria are also observed in and recultured from the tissue surrounding implants, and may even reside inside host cells. Whether these bacteria originate from biofilms is not known. Therefore, we investigated the fate of Staphylococcus epidermidis inoculated on the surface of implants as adherent planktonic cells or as a biofilm in mouse experimental biomaterial-associated infection. In order to discriminate the challenge strain from potential contaminating mouse microflora, we constructed a fully virulent green fluorescent S. epidermidis strain. S. epidermidis injected along subcutaneous titanium implants, pre-seeded on the implants or pre-grown as biofilm, were retrieved from the implants as well as the surrounding tissue in all cases after 4days, and in histology bacteria were observed in the tissue co-localizing with macrophages. Thus, bacteria adherent to or in a biofilm on the implant are a potential source of infection of the surrounding tissue, and antimicrobial strategies should prevent both biofilm formation and tissue colonization.

Development of a standardized and safe airborne antibacterial assay, and its evaluation on antibacterial biomimetic model surfaces

Bacterial infection of biomaterials is a major concern in medicine, and different kinds of antimicrobial biomaterial have been developed to deal with this problem. To test the antimicrobial performance of these biomaterials, the airborne bacterial assay is used, which involves the formation of biohazardous bacterial aerosols. We here describe a new experimental set-up which allows safe handling of such pathogenic aerosols, and standardizes critical parameters of this otherwise intractable and strongly user-dependent assay. With this new method, reproducible, thorough antimicrobial data (number of colony forming units and live-dead-stain) was obtained. Poly(oxonorbornene)-based Synthetic Mimics of Antimicrobial Peptides (SMAMPs) were used as antimicrobial test samples. The assay was able to differentiate even between subtle sample differences, such as different sample thicknesses. With this new set-up, the airborne bacterial assay was thus established as a useful, reliable, and realistic experimental method to simulate the contamination of biomaterials with bacteria, for example in an intraoperative setting.

Bacterial contamination of the wound during primary total hip and knee replacement. Median 13 years of follow-up of 90 replacements

BACKGROUND AND PURPOSE

Previous work has shown that despite preventive measures, intraoperative contamination of joint replacements is still common, although most of these patients seem to do well in follow-up of up to 5 years. We analyzed the prevalence and bacteriology of intraoperative contamination of primary joint replacement and assessed whether its presence is related to periprosthetic joint infection (PJI) on long-term follow-up.

PATIENTS AND METHODS

49 primary total hip replacements (THRs) and 41 total knee replacements (TKRs) performed between 1990 and 1991 were included in the study. 4 bacterial swabs were collected intraoperatively during each procedure. Patients were followed up for joint-related complications until March 2011.

RESULTS

19 of 49 THRs and 22 of 41 TKRs had at least 1 positive culture. Coagulase-negative staphylococci and Staphylococcus aureus were the most common organisms, contaminating 28 and 9 operations respectively. Where information was available, bacteria from 27 of 29 contaminated operations were susceptible to the prophylactic antibiotic administered. 13% of samples gathered before 130 min of surgery were contaminated, as compared to 35% collected after that time. 2 infections were diagnosed, both in TKRs. 1 of them may have been related to intraoperative contamination.

INTERPRETATION

Intraoperative contamination was common but few infections occurred, possibly due to the effect of prophylactic antibiotics. The rate of contamination was higher with longer duration of surgery. It appears that positive results from intraoperative swabs do not predict the occurrence of PJI.

Biomaterial-associated infection: locating the finish line in the race for the surface

Biomaterial-associated infections occur on both permanent implants and temporary devices for restoration or support of human functions. Despite increasing use of biomaterials in an aging society, comparatively few biomaterials have been designed that effectively reduce the incidence of biomaterial-associated infections. This review provides design guidelines for infection-reducing strategies based on the concept that the fate of biomaterial implants or devices is a competition between host tissue cell integration and bacterial colonization at their surfaces.

Economical analysis on prophylaxis, diagnosis, and treatment of periprosthetic infections

The economic burden of periprosthetic infections is enormous, but the number of economic studies dealing with this issue is very scarce. This review tries to know the economic literature existing, assess the value of current data, and recognize the less costly and more effective procedures for prevention, diagnosis and treatment of periprosthetic infections. Forty five studies meeting the inclusion criteria and adhering to the quality criteria used were carefully analyzed to extract the economic data of relevance in evaluating the magnitude of problem and the more cost-effective solutions. However, because the heterogeneity and the low-quality of most of these studies meta-analytical technique has not been possible. Instead, the studies have been reviewed descriptively. Optimizing the antibiotic use in the prevention and treatment of periprosthetic infection, combined with systemic and behavioral changes in the operating room; detecting and treating the high-risk groups; a quick, simple, reliable, safe, and cost-effective diagnosis, and the rationale management of the instituted infection, specifically using the different procedures according to each particular case, could allow to improve outcomes and produce the highest quality of life for patients and the lowest economic impact. Nevertheless, the cost effectiveness of different interventions to prevent and to treat the periprosthetic infection remains unclear.

Bacterial DNA from orthopedic implants after routine removal

Bacterial 16S rDNA was monitored and identified from orthopedic metallic implants after routine or septic removal from patients in a German hospital. From March to June 2009, 28 metallic implants, 10 human biopsies, and 6 foam dressings from 28 patients were investigated. After analysis of this first collective, the methods were optimized to enhance sensitivity and to reduce interference with human DNA. Then a second collective consisting of 21 metallic implants from 21 patients was investigated from June 2009 to January 2010. In the first collective, 71% of the metallic implants were negative for eubacterial DNA. Pathogens such as Staphylococcus aureus and opportunists such as Lactobacillus rhamnosus were identified in 11% of the samples, whereas the residual 18% positive results were classified as from skin sources or could not be confirmed. Tissue, secretion, and bone samples as well as foam dressings from the same collective also contained pathogens and opportunists. After the optimization of the methods, a considerable increase of positive samples was seen: in the second collective 19 of the 21 metallic implants proved to be positive for eubacterial 16S rDNA. Bacterial DNA from environmental sources was detected in 13 samples, and in 20 specimens, predominantly mostly the skin. Opportunistic pathogens were detected in 19 samples. Interestingly, septic complications did not occur despite the presence of bacterial DNA. The results obtained up to now encourage us not only to continue a directed monitoring of bacterial DNA on orthopedic implants in practice but also to look intensely for possible sources of bacterial contamination during and after insertion or during removal of such implants.

Hard implant coatings with antimicrobial properties

Infection of orthopaedic implants often leads to inflammation immediately after surgery and increases patient morbidity due to repetitive operations. Silver ions have been shown to combine good biocompatibility with a low risk of inducing bacterial resistance. In this study a physical vapour deposition system using both arc deposition and magnetron sputtering has been utilized to produce silver ion doped TiN coatings on Ti substrates. This biphasic system combines the advantages of silver induced bactericidity with the good mechanical properties of TiN. Crystallographic analysis by X-ray diffraction showed that silver was deposited as well in its elementary form as it was incorporated into the crystal lattice of TiN, which resulted in increasing hardness of the TiN-coatings. Elution experiments revealed a continuous release of Ag ions in phosphate buffered saline. The coatings showed significant inhibitory effects on the growth of Staphylococcus epidermidis and Staphylococcus aureus and practically no cell-toxicity in cytocompatibility tests.

Relationship between Intraoperative Cultures during Hip Arthroplasty, Obesity, and the Risk of Early Prosthetic Joint Infection: A Prospective Study of 428 Patients

Purpose

To evaluate the relationship between intraoperative cultures during hip arthroplasty, the different patient characteristics, and the risk of developing a prosthetic joint infection (PJI).

Methods

A prospective observational study was performed. Patients who underwent elective THA from March 2007 to March of 2011 were included. Three samples were taken just after arthrotomy: synovial fluid inoculated into blood culture flasks (SF), a tissue sample (TS), and a swab of periprosthetic tissue (S). Patients received standard antibiotic prophylaxis. The PJI rate within the first 3 months after arthroplasty was recorded.

Results

402 prostheses were included in the study. Contamination rate of synovial fluid was 10.2%. The most frequent isolated microorganism was coagulase-negative staphylococci (CoNS) (32 out of 41). Body mass index (BMI) was the only host characteristic associated with positive intraoperative culture (p=0.009). The PJI rate was 3.7%. Variables associated with PJI in the univariate and multivariate analysis were: age ≥67 years (p=0.012 OR: 5.35 (1.45–19.81); CI95%) and a BMI ≥35 (p=0.002, OR: 7.7 (2.12–27.85) CI95%). PJI rate among patients with BMI<35 with negative and positive intraoperative cultures was 3% and 2.7%, respectively, however, the rate among patients with BMI ≥ 35 was 15% and 25%, respectively.

Conclusion

A BMI ≥35 was associated with a higher risk of positive intraoperative culture during hip arthroplasty. In addition, a BMI ≥35 was independently associated with a high risk of PJI and the highest rate was documented among obese patients with positive intraoperative cultures.

Unexpectedly increased rate of surgical site infections following implant surgery for hip fractures: problem solution with the bundle approach

INTRODUCTION

Surgical site infections (SSIs) are the most common nosocomial infections after surgery.However, clinical guidance on how to handle any suspicious clusters of SSI in orthopaedic surgery is missing. We report on problem analysis and solution finding following the observation of an increased rate of SSI in trauma implant surgery.

SETTING

Trauma unit of a university hospital.

METHODS

Over a 2-year observation period, all patients (n = 370) following surgical stabilisation of proximal femur fractures in a trauma unit of a university hospital were consecutively followed using a standardised case report form. First, a retrospective cohort of 217 patients was collected for whom an increased SSI rate was detected. Based on risk analysis, new standard perioperative procedures were developed and implemented. The impact was evaluated in a prospective cohort of 153 comparable patients. Uni- and multivariable analysis of factors associated with the risk for SSI was undertaken.

RESULTS

The intervention bundle resulted in a significant reduction of an initially increased SSI incidence of 6.9 (down) to 2.0% (p = 0.029). Multivariable analysis revealed four risk factors significantly associated with a higher risk of SSI caused by different bacteria: duration of surgery (p = 0.002), hemiarthroplasty(p = 0.002), haematoma (p = 0.004) and the presence of two operating room staff members (p < 0.001 and 0.035).

CONCLUSIONS

A standardised prospective SSI protocol and detection system offering the simultaneous use of data should guarantee every institution immediate alarm registration to avoid comparable problem situations. Detailed interdisciplinary analysis followed by the implementation of coherent interventions, based on a best-evidence structured bundle approach, may adequately resolve similar critical incidence episodes.

Blood culture flasks for culturing synovial fluid in prosthetic joint infections

BACKGROUND

Identifying the etiologic microorganism is essential to guide antimicrobial therapy in prosthetic joint infection.

QUESTIONS/PURPOSE

We (1) compared the frequency of positive cultures with synovial fluid inoculated in blood culture flasks (SF) with those of periprosthetic tissues or swabs in traditional cultures from patients with acute and chronic prosthetic joint infections (PJI) and (2) determined the sensitivity, specificity, and predictive values of the three methods.

PATIENTS AND METHODS

We retrospectively reviewed 87 patients with PJIs (54 knees, 33 hips) and 63 patients with aseptic loosening (34 knees, 29 hips). Two SF, periprosthetic tissue, and swab samples were taken for culture in all 150 patients except for 14 in whom only one SF fluid sample was obtained. Synovial fluid was inoculated in blood culture flasks and periprosthetic tissue and swab samples in standard media. Positive cultures were identified with standard biochemical procedures.

RESULTS

SF samples were positive in 78 of 87 infected cases (90%), periprosthetic tissue samples were positive in 71 (82%), and swab samples were positive in 59 (68%). SF, periprosthetic tissue, and swab samples were positive more frequently in acute than in chronic infections (96% versus 82% for SF, 87% versus 74% for periprosthetic tissue, and 87% versus 44% for swabs). The sensitivity, specificity, and positive and negative predictive values of SF were 91, 100, 100, and 93 for acute infections and 79, 100, 100, and 88 for chronic infections, respectively.

CONCLUSIONS

SF samples cultured in flasks had higher sensitivity, specificity, and positive and negative predictive values for diagnosis of PJI when compared with standard tissue and swab samples. The usefulness of all samples was less in chronic than in acute infections.

LEVEL OF EVIDENCE

Level II, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Complications after spacer implantation in the treatment of hip joint infections

The aim of this retrospective study was to identify and evaluate complications after hip spacer implantation other than reinfection and/or infection persistence. Between 1999 and 2008, 88 hip spacer implantations in 82 patients have been performed. There were 43 male and 39 female patients at a mean age of 70 [43-89] years. The mean spacer implantation time was 90 [14-1460] days. The mean follow-up was 54 [7-96] months. The most common identified organisms were S. aureus and S. epidermidis. In most cases, the spacers were impregnated with 1 g gentamicin and 4 g vancomycin/80 g bone cement. The overall complication rate was 58.5% (48/82 cases). A spacer dislocation occurred in 15 cases (17%). Spacer fractures could be noticed in 9 cases (10.2%). Femoral fractures occurred in 12 cases (13.6%). After prosthesis reimplantation, 16 patients suffered from a prosthesis dislocation (23%). 2 patients (2.4%) showed allergic reactions against the intravenous antibiotic therapy. An acute renal failure occurred in 5 cases (6%). No cases of hepatic failure or ototoxicity could be observed in our collective. General complications (consisting mostly of draining sinus, pneumonia, cardiopulmonary decompensation, lower urinary tract infections) occurred in 38 patients (46.3%). Despite the retrospective study design and the limited possibility of interpreting these findings and their causes, this rate indicates that patients suffering from late hip joint infections and being treated with a two-stage protocol are prone to having complications. Orthopaedic surgeons should be aware of these complications and their treatment options and focus on the early diagnosis for prevention of further complications. Between stages, an interdisciplinary cooperation with other facilities (internal medicine, microbiologists) should be aimed for patients with several comorbidities for optimizing their general medical condition.

[Applications of molecular pathology in the diagnosis of joint infections]

The diagnosis of infections in patients with arthritis and/or joint prostheses requires interdisciplinary cooperation and the use of up-to-date methods. Massive bacterial infection can be identified by bacterial culture, and minimal infection can be detected by molecular pathological methods. These processes include specific enrichment of bacterial and fungal DNA, amplification, and identification of the DNA by gel electrophoresis, sequencing techniques, and chip technologies.Anamnesis (enteral or urogenital infection), the clinical picture (oligoarthritis), and further parameters (e.g., HLA B27 status) are important for the diagnosis of reactive arthritis. In many cases of reactive arthritis, molecular methods allow detection of bacterial DNA or RNA in synovial fluid or tissue. Molecular pathological methods allow the fast and reliable differential diagnosis of granulomatous synovialitis without prior cultivation of bacteria or fungi. The development of new molecular pathological methods for detecting bacterial and fungal nucleic acids will increase diagnostic accuracy.

[Classification of prosthetic loosening and determination of wear particles]

Nowaday, loosening of orthopaedic implants implies important medical and socioeconomic problems. Implant loosening is caused by implant infections as well as aseptic loosening, due to particle disease and mechanical alterations. Clinically we divide the implant infection into early and late infections. Morphologically it is possible to reliably detect the infection by quantification of neutrophil granulocytes. Additionally molecular methods are suitable to detect micro-organisms which are responsible for the prosthetic joint infection including their resistance to antibiotics. Particle disease may be reproducibly classified by the detection of different types of wear particles, particularly polyethylene, metal, ceramic and cement. The aetiology of the indeterminate type of the periprosthetic membrane is obscure, but may be associated with osteopathies. This classification of the periprosthetic membrane morphology provides clinically significant information concerning clinical management of implant loosening.

Procrastination of wound drainage and malnutrition affect the outcome of joint arthroplasty

The association between wound drainage and subsequent periprosthetic infection is well known. However, the most appropriate treatment of wound drainage is not well understood. We retrospectively reviewed the records of 10,325 patients (11,785 procedures), among whom 300 patients (2.9%) developed persistent (greater than 48 hours postoperatively) wound drainage. Wound drainage stopped spontaneously between 2 and 4 days in 217 patients treated with local wound care and oral antibiotics. The remaining 83 patients (28%) underwent further surgery. A single débridement resulted in cessation of drainage without subsequent infection in 63 of 83 patients (76%), whereas 20 (24%) patients continued to drain and underwent additional treatment (repeat débridement, resection arthroplasty, or long-term antibiotics). Timing of surgery and the presence of malnutrition predicted failure of the first débridement. There were no differences between the success and failure groups with regard to all other examined parameters, including demographic or surgical factors.

LEVEL OF EVIDENCE

Level III, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.