Methicillin-resistant Staphylococcus aureus on orthopaedic wards: incidence, spread, mortality, cost and control

Orthogeriatric co-management for the care of older subjects with hip fracture: recommendations from an Italian intersociety consensus

BACKGROUND

Health outcomes of older subjects with hip fracture (HF) may be negatively influenced by multiple comorbidities and frailty. An integrated multidisciplinary approach (i.e. the orthogeriatric model) is, therefore, highly recommended, but its implementation in clinical practice suffers from the lack of shared management protocols and poor awareness of the problem. The present consensus document has been implemented to address these issues.

AIM

To develop evidence-based recommendations for the orthogeriatric co-management of older subjects with HF.

METHODS

A 20-member Expert Task Force of geriatricians, orthopaedics, anaesthesiologists, physiatrists, physiotherapists and general practitioners was established to develop evidence-based recommendations for the pre-, peri-, intra- and postoperative care of older in-patients (≥ 65 years) with HF. A modified Delphi approach was used to achieve consensus, and the U.S. Preventive Services Task Force system was used to rate the strength of recommendations and the quality of evidence.

RESULTS

A total of 120 recommendations were proposed, covering 32 clinical topics and concerning preoperative evaluation (11 topics), perioperative (8 topics) and intraoperative (3 topics) management, and postoperative care (10 topics).

CONCLUSION

These recommendations should ease and promote the multidisciplinary management of older subjects with HF by integrating the expertise of different specialists. By providing a convenient list of topics of interest, they might assist in identifying unmet needs and research priorities.

Outcomes following Revision Total Knee Arthroplasty Septic versus Aseptic Failure: A National Propensity-Score-Matched Comparison

Although periprosthetic joint infection (PJI) has been hypothesized to increase the risk of complications following revision total knee arthroplasty (TKA), strong evidence linking the two is lacking. The aim of this study was to determine whether PJI is an independent risk factor for inpatient perioperative complications, and increased resource use in patients undergoing revision TKA. We relied on the US Nationwide Inpatient Sample (NIS) to identify patients with PJI or non-PJI treated with revision TKA between 2002 and 2014. Overall, 5,316 (16.4%) and 27,033 (83.6%) patients were categorized as PJI and non-PJI, respectively. To adjust for potential baseline differences between the two groups, propensity-score-based matching was performed. This resulted in 5,187 (50%) PJI patients matched to 5,187 (50%) non-PJI patients. The rates of postoperative complications, blood transfusions, prolonged length of stay (pLOS), in-hospital cost, and in-hospital mortality were assessed for both groups. Multivariable logistic regression analyses were performed within the cohort after propensity-score matching. For PJI versus non-PJI, respectively, the following rates were recorded: blood transfusions, 28.3 versus 18.4% (p < 0.0001); postoperative complications, 27.5 versus 19.8% (p < 0.0001); pLOS (>4 d), 61.9 versus 26.9% (p < 0.0001); in-hospital cost (>$39,929), 55.8 versus 44.2% (p < 0.0001); in-hospital mortality, 0.6 versus 0.3% (p = 0.016). In multivariable logistic regression analyses, PJI patients were more likely to receive a blood transfusion (odds ratio [OR]: 1.78; p < 0.0001), to experience postoperative complications (OR: 1.56; p < 0.0001), to have a higher in-hospital cost (OR: 1.65; p < 0.0001), to have a pLOS following surgery following surgery (OR: 4.69; p < 0.0001), and to have a higher in-hospital mortality (OR: 2.14; p = 0.019). After adjustment for potential selection biases, PJI is associated with more adverse perioperative outcomes and resource use than non-PJI patients. This is a Level II (level of evidence), prognostic study.

Locally delivered adjuvant biofilm-penetrating antibiotics rescue impaired endochondral fracture healing caused by MRSA infection

Infection is a devastating complication following an open fracture. We investigated whether local rifampin-loaded hydrogel can combat infection and improve healing in a murine model of methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis. A transverse fracture was made at the tibia midshaft of C57BL/6J mice aged 10-12 weeks and stabilized with an intramedullary pin. A total of 1 × 106 colony-forming units (CFU) of MRSA was inoculated. A collagen-based hydrogel containing low-dose (60 μg) and high-dose (300 μg) rifampin was applied before closure. Postoperative treatment response was assessed through bacterial CFU counts from tissue and hardware, tibial radiographs and microcomputed tomography (μCT), immunohistochemistry, and histological analyses. All untreated MRSA-infected fractures progressed to nonunion by 28 days with profuse MRSA colonization. Infected fractures demonstrated decreased soft callus formation on safranin O stain compared to controls. Areas of dense interleukin-1β stain were associated with poor callus formation. High-dose rifampin hydrogels reduced the average MRSA load in tissue (p < 0.0001) and implants (p = 0.041). Low-dose rifampin hydrogels reduced tissue bacterial load by 50% (p = 0.021). Among sterile models, 88% achieved union compared to 0% of those infected. Mean radiographic union scale in tibia scores improved from 6 to 8.7 with high-dose rifampin hydrogel (p = 0.024) and to 10 with combination local/systemic rifampin therapy (p < 0.0001). μCT demonstrated reactive bone formation in MRSA infection. Histology demonstrated restored fracture healing with bacterial elimination. Rifampin-loaded hydrogels suppressed osteomyelitis, prevented implant colonization, and improved healing. Systemic rifampin was more effective at eliminating infection and improving fracture healing. Further investigation into rifampin-loaded hydrogels is required to correlate these findings with clinical efficacy.

What is the most cost-effective strategy for nasal screening and Staphylococcus aureus decolonization in patients undergoing total hip arthroplasty?

Background

To reduce periprosthetic joint infection after total hip arthroplasty (THA), several nasal screening and decolonization strategies for methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) have been performed. These include universal decolonization (UD; i.e., no screening and decolonization for all patients), universal screening and target decolonization (US; i.e., screening for all patients and decolonization for bacterial positive patients), and target screening and decolonization (TS; i.e., screening and decolonization for high-risk populations only). Although TS is the most cost-effective strategy, useful risk factors must be identified. The purpose of this study was to evaluate the presence of predictive factors that enable the TS strategy to be successfully implemented and to compare the costs of each strategy.

Methods

A total of 1654 patients scheduled for primary or revision THA (1464 female, 190 male; mean age 64 years) were screened prior to surgery for bacterial colonization of the nasal mucosa. Risk factors for positive MRSA and S. aureus (including both MRSA and MSSA) tests were analyzed according to the following parameters: sex, age ≥ 80 years, body mass index ≥ 30 kg/m², antibiotic use within 3 years, corticosteroid use, serum albumin < 3.5 g/dL, glomerular filtration rate < 50 mL/min, presence of brain, thyroid, cardiac, or pulmonary disease, diabetes, asthma, smoking status, and whether revision surgery was performed. The average cost of each strategy was calculated.

Results

In total, 29 patients (1.8 %) tested positive for MRSA and 445 (26.9 %) tested positive for S. aureus. No parameters were identified as independent risk factors for MRSA and only female sex was identified as a risk factor for S. aureus (p = 0.003; odds ratio: 1.790; 95 % confidence interval: 1.210–2.640). The average cost of each strategy was 1928.3 yen for UD, 717.6 yen for US, and 717.6 yen for TS (for eradicating MRSA), and 1928.3 yen for UD, 1201.6 yen for US, and 1160.4 yen for TS (for eradicating S. aureus).

Conclusions

No useful predictive parameters for implementing the TS strategy were identified. Based on cost implications, US is the most cost-effective strategy for THA patients.

Biofilm Producing Staphylococcus epidermidis (RP62A Strain) Inhibits Osseous Integration Without Osteolysis and Histopathology in a Murine Septic Implant Model

Despite its presence in orthopaedic infections, Staphylococcus epidermidis's ability to directly induce inflammation and bone destruction is unknown. Thus, we compared a clinical strain of methicillin-resistant biofilm-producing S. epidermidis (RP62A) to a highly virulent and osteolytic strain of methicillin-resistant Staphylococcus aureus (USA300) in an established murine implant-associated osteomyelitis model. Bacterial burden was assessed by colony forming units (CFUs), tissue damage was assessed by histology and micro-computed tomography, biofilm was assessed by scanning electron microscopy (SEM), host gene expression was assessed by quantitative polymerase chain reaction, and osseous integration was assessed via biomechanical push-out test. While CFUs were recovered from RP62A-contaminated implants and surrounding tissues after 14 days, the bacterial burden was significantly less than USA300-infected tibiae (p < 0.001). In addition, RP62A failed to produce any of the gross pathologies induced by USA300 (osteolysis, reactive bone formation, Staphylococcus abscess communities, marrow necrosis, and biofilm). However, fibrous tissue was present at the implant-host interface, and rigorous SEM confirmed the rare presence of cocci on RP62A-contaminated implants. Gene expression studies revealed that IL-1β, IL-6, RANKL, and TLR-2 mRNA levels in RP62A-infected bone were increased versus Sterile controls. Ex vivo push-out testing showed that RP62A-infected implants required significantly less force compared with the Sterile group (7.5 ± 3.4 vs. 17.3 ± 4.1 N; p < 0.001), but required 10-fold greater force than USA300-infected implants (0.7 ± 0.3 N; p < 0.001). Taken together, these findings demonstrate that S. epidermidis is a commensal pathogen whose mechanisms to inhibit osseous integration are limited to minimal biofilm formation on the implant, and low-grade inflammation. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:852-860, 2020.

Can we reduce the number of MRSA screening site swabs in elective orthopedic patients?

BACKGROUND

Deep infection after routine elective orthopedic procedures can be catastrophic, leading to further surgery, loss of limb, disability, and risk of mortality. Ring-fencing elective orthopedic ward has been shown to significantly reduce the incidence of all postoperative infections especially with methicillin-resistant Staphylococcus aureus (MRSA). Our hospital's current MRSA screening is a four-site MRSA swabs.

OBJECTIVES

This study evaluates the possibility of reducing the number of MRSA swab sites as part of a quality improvement project.

STUDY DESIGN AND METHODS

Patients on the waiting list for elective orthopedic procedure in our trust who had an MRSA-positive swab from either four sites were analyzed over the time period from January 2012 to December 2014. Those without swabs from all four areas (nose, throat, axilla, and groin) were excluded. Positive swabs of different regions were recorded and compared.

RESULTS

There were 138 MRSA-positive patients, giving an incidence of 31 per 10,000 screen/year over that time period. Some patients ( n = 31, 22.5%) had a positive swab in more than one site. The positive sites were as follows: nose (69.60%, n = 96), groin (26.10%, n = 36), throat (25.30%, n = 35), and axilla (8.70%, n = 12). In our cohort, we would miss a significant proportion of positive patients if we change it to a two swab screening policy (26.8% for nose and axilla combination; 18.10% for nose and groin combination; and 15.20% for nose and throat). However, we would only miss 2.2% of cases for a nose, groin, and throat three-swab policy. There were also 11 instances, where a previously negative site become positive in the next swab.

CONCLUSION

A three-swab combination of nasal, throat, and groin swabs improves pickup rate of MRSA significantly compared to a two-swab policy and misses only 2.2% compared to a four-swab policy. Axilla swabbing does not make a significant difference to the results. Based on this study, the policy has now been changed from a four-swab to three-swab screening in our trust. This has now been audited four times and they were all negative. This has helped to reduce cost in terms of staff time and resources. We would not recommend screening only the previous positive site for the next repeat screening swabs as there is an 8% chance of missing MRSA carrier status.

Methicillin-Resistant Staphylococcus Aureus Carrier Rate in Orthopaedic Trauma Patients: A Prospective Cohort Study

OBJECTIVES

To identify the methicillin-resistant Staphylococcus aureus (MRSA) carrier rate among surgical patients on an orthopaedic trauma service and to determine whether screening is an effective tool for reducing postoperative MRSA infection in this population.

DESIGN

Prospective.

SETTING

Level 1 trauma center.

PATIENTS/PARTICIPANTS

Two hundred forty-eight patients with operatively managed orthopaedic trauma conditions during the study period. Two hundred three patients (82%) had acute orthopaedic trauma injuries. Forty-five patients (18%) underwent surgery for a nonacute orthopaedic trauma condition, including 36 elective procedures and 9 procedures to address infection.

INTERVENTION

MRSA screening protocol, preoperative antibiotics per protocol.

MAIN OUTCOME MEASUREMENTS

MRSA carrier rate, overall infection rate, MRSA infection rate.

RESULTS

Our screening captured 71% (175/248) of operatively treated orthopaedic trauma patients during the study period. The overall MRSA carrier rate was 3.4% (6/175). When separated by group, the acute orthopaedic trauma cohort had an MRSA carrier rate of 1.4% (2/143), and neither MRSA-positive patient developed a surgical site infection. Only one MRSA infection occurred in the acute orthopaedic trauma cohort. The nonacute group had a significantly higher MRSA carrier rate of 12.5% (4/32, P = 0.01), and the elective group had the highest MRSA carrier rate of 15.4% (4/26, P < 0.01). The odds ratio of MRSA colonization was 10.1 in the nonacute group (95% confidence interval, 1.87-75.2) and 12.8 for true elective group (95% confidence interval, 2.36-96.5) when compared with the acute orthopaedic trauma cohort.

CONCLUSIONS

There was a low MRSA colonization rate (1.4%) among patients presenting to our institution for acute fracture care. Patients undergoing elective surgery for fracture-related conditions such as nonunion, malunion, revision surgery, or implant removal have a significantly higher MRSA carrier rate (15.4%) and therefore may benefit from MRSA screening. Our results do not support routine vancomycin administration for orthopaedic trauma patients whose MRSA status is not known at the time of surgery.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Reduction of periprosthetic Staphylococcus aureus infection by preoperative screening and decolonization of nasal carriers undergoing total knee arthroplasty

Objective

The aim of this study was to evaluate whether the establishment of a preoperative screening and decolonization protocol for Staphylococcus aureus carriers undergoing total knee arthroplasty (TKA) could decrease the incidence of periprosthetic joint infection (PJI) caused by this microorganism.

Methods

We conducted a retrospective study comparing a control group comprising 400 patients (134 men, and 266 women; mean age: 72.2 ± 6.8 years) who went through surgery between January 2009 and December 2013, with a second intervention group of 403 patients (125 men, and 278 women; mean age: 72.4 ± 6.9 years) in which the protocol of screening and decolonization of S. aureus nasal carriers was applied between January 2014 and December 2016. During this latter period patients were preoperatively screened and, if positive, treated with mupirocin nasal ointment and chlorhexidine soap, for 5 days prior to surgery.

Results

In the control group, 17 of 400 patients (4.2%) had a SSI, 8 (2%) of them caused by S. aureus and 9 (2.2%) by other microorganisms. In the intervention group 20.6% of patients had a positive S. aureus nasal swab and were treated according to the protocol. 5 of 403 patients (1.2%) in this group had a SSI, 1 (0.2%) due to S. aureus and 4 (1%) to other microorganisms. When comparing surgical-site infection (SSI) rates between the two groups, we found a statistically significant reduction in both global SSI (p = 0.009) and specifically S. aureus SSI (p = 0.02), in the intervention group. No decolonized S. aureus nasal carrier presented a SSI.

Discussion

In patients undergoing TKA a preoperative screening and decolonization protocol for S. aureus nasal carriers, using mupirocin nasal ointment and chlorhexidine soap, is an effective measure to reduce the rate of SSI caused by this microorganism.

Level of Evidence

Level III; Therapeutic Study.

Manual polishing of 3D printed metals produced by laser powder bed fusion reduces biofilm formation

Certain 3D printed metals and surface finishes may be better suited for canine patient specific orthopedic implants on the basis of minimizing potential bacterial biofilm growth. Thirty disks each of titanium alloy, stainless steel, and cobalt chromium alloy were 3D printed via laser powder bed fusion. Fifteen disks of each metal were subsequently polished. After incubation with a robust biofilm-forming methicillin-resistant Staphylococcus pseudintermedius isolate, disks were rinsed and sonicated to collect biofilm bacteria. Serial dilutions were plated on blood agar, and colony forming units were counted log (ln) transformed for analysis of variance. Interference microscopy quantified surface roughness for comparison to biofilm growth. Scanning electron microscopy on both pre- and post-sonicated disks confirmed biofilm presence and subsequent removal, and visualized surface features on cleaned disks. Significantly more bacteria grew on rough versus polished metal preparations (p < 0.0001). Titanium alloy had more bacterial biofilm growth compared to cobalt chromium alloy (p = 0.0001) and stainless steel (p < 0.0001). There were no significant growth differences between cobalt chromium alloy and stainless steel (p = 0.4737). Relationships between biofilm growth and surface roughness varied: positive with the rough preparations and negative with the smooth. Polished preparations had increased variance in surface roughness compared to rough preparations, and within disk variance predominated over between disk variance for all preparations with the exception of rough cobalt chromium alloy and rough stainless steel. Using scanning electron microscopy, bacterial biofilms tended to form in crevices. Overall, manual polishing of 3D printed surfaces significantly reduced biofilm growth, with preparation-specific relationships between surface roughness and biofilm growth. These results suggest that metallic implants produced by laser powder bed fusion should be polished. Further research will elucidate the optimal surface roughness per preparation to reduce potential biofilm formation and implant associated infection.

Predictors of colonization with Staphylococcus species among patients scheduled for cardiac and orthopedic interventions at tertiary care hospitals in north-eastern Germany-a prevalence screening study

As methicillin-resistant Staphylococcus aureus (MRSA) colonization and infection in humans are a global challenge. In Mecklenburg and Western Pomerania (Germany) 1,517 patients who underwent surgical interventions were systematically screened for MRSA and MSSA colonization on the day of hospital admission and discharge. Demographic data, risk factors and colonization status of the (i) nose, (ii) throat, (iii) groin, and (iv) thorax or site of surgical intervention were determined. Of the 1,433 patients who were included for further evaluation, 331 (23.1%) were colonized with MSSA, while only 17 (1.2%) were MRSA carriers on the day of hospital admission. A combination of nose, throat and groin swabs returned a detection rate of 98.3% for MSSA/MRSA. Trauma patients had lower prevalence of MRSA/MSSA (OR 0.524, 95% CI: 0.37-0.75; p < 0.001) than patients with intended orthopedic interventions. Males showed significantly higher nasal S. aureus carrier rates than females (odds ratio (OR) = 1.478; 95% CI: 1.14-1.92; p = 0.003). Nasal S. aureus colonization was less frequent among male smokers as compared to non-smokers (chi² = 16.801; phi = 0.154; p < 0.001). Age, gender and smoking had a significant influence on S. aureus colonization. Combining at least three different swabbing sites should be considered for standard screening procedure to determine S. aureus colonization at patients scheduled for cardiac or orthopedic interventions at tertiary care hospitals.

Can preoperative nasal cultures of Staphylococcus aureus predict infectious complications or outcomes following repair of fracture nonunion?

INTRODUCTION

Much has been studied with reference to methicillin resistant Staphylococcus aureus (MRSA) and methicillin sensitive S. aureus (MSSA) colonization and associated outcomes and comorbidities. In the area of Orthopedic surgery, literature predominantly comes from the field of arthroplasty. Little is known about outcomes of fracture and Orthopedic trauma patients in the setting of S. aureus colonization. We believe that MRSA/MSSA colonization in and of itself may be a weak marker for generally poor protoplasm, potentially with complex medical history including previous hospitalization or rehab placement. This milieu of risk factors may or may not contribute to poorer outcomes after fracture and fracture nonunion surgery. The purpose of this study is to determine if nasal swabbing for S. aureus (MRSA or MSSA) carriage can predict operative culture, complications, or outcomes following fracture nonunion surgery.

METHODS

Sixty-two consecutive patients undergoing surgery for fracture nonunion were prospectively followed. Data analyses were performed using grouped MRSA and MSSA carriers (Staphylococcus carriers: SC). Outcomes analyzed included time to healing, need for additional surgery, and persistent nonunion.

RESULTS

Twenty-six percent of patients (16/62) were identified as MSSA carriers, an additional 6.5% (4/62) carried MRSA. Follow-up of at least 12-months was obtained on 90% (56/62) of patients. White blood cell counts, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) values did not differ between SCs and non-carriers pre-operatively. Carriers were just as likely as non-carriers to culture positively for any pathogen at the time of surgery. Although SC's were three times as likely as non-carriers to grow S. aureus (15% vs. 5%), this difference did not reach statistical significance (p=0.3). Post-operative wound complications, antibiotic use, pain at follow-up and progression to healing did not differ between groups.

CONCLUSIONS

Ultimately, pre-operative nasal swabbing for S. aureus is a simple and non-invasive diagnostic tool with prognostic implications in patients undergoing fracture nonunion surgery. This study found that MRSA and MSSA colonized patients with fracture nonunion of long bones do not have an increased association with positive cultures or a predisposition towards greater post-operative infectious complications.

Infection after fracture osteosynthesis - Part I

Bone and surgical site infections after osteosynthesis are notoriously difficult to manage and pose a tremendous burden in fracture management. In this article, we use the term osteosynthesis-associated infection (OAI) to refer to this clinical entity. While relatively few surgically treated fractures become infected, it is challenging to perform a rapid diagnosis. Optimal management strategies are complex and highly customized to each scenario and take into consideration the status of fracture union, the presence of hardware and the degree of mechanical stability. At present, a high level of relevant evidence is unavailable; most findings presented in the literature are based on laboratory work and non-randomized clinical studies. We present this overview of OAI in two parts: an examination of recent literature concerning OAI pathogenesis, diagnosis and classification and a review of treatment options.

Burden of Surgical Site Infections Associated with Arthroplasty and the Contribution of Staphylococcus aureus

BACKGROUND

Patients undergoing arthroplasty are at considerable risk of experiencing post-operative complications, including surgical site infections (SSIs). In addition to potential economic consequences, SSIs can have a negative impact on patient outcomes and may potentially be life-threatening. Staphylococcus aureus has been consistently shown as the leading cause of SSIs associated with orthopedic surgery, with an important contribution from methicillin-resistant S. aureus (MRSA). This study evaluated the global burden of SSIs among patients undergoing orthopedic surgical procedures, and specifically those undergoing knee and hip arthroplasties.

METHODS

An extensive search of PubMed and recent conference proceedings was conducted. English articles published between 2003 and 2013 pertaining to SSI epidemiology, patient outcomes, and healthcare resource utilization and costs were reviewed.

RESULTS

Overall, 81 studies were included, mainly from North America and Europe. Median SSI and S. aureus SSI rates, calculated as percentage of all arthroplasty procedures, were 1.7% (range: 0.25%-4.4%; 15 studies) and 0.6% (range: 0.1%-23%), respectively. Median SSI rates were 1.3% (range: 0.05%-19%; 22 studies) after knee arthroplasty, and 2.1% (range: 0.05%-28%; 24 studies) after hip arthroplasty. S. aureus SSI rates ranged from 0.2%-2.4% and 0.18%-3.8% for patients undergoing knee and hip arthroplasty, respectively. The percentage of S. aureus SSIs because of MRSA varied widely within each patient category. SSI-related mortality data (14 studies) showed that in-hospital mortality rates were low (1.2%-2.5%), but increased with time after index arthroplasty procedure (up to 56% over 1 y). Studies assessing healthcare resource utilization (n = 21) revealed that developing post-orthopedic SSIs resulted in a two- to three-fold increase in length of hospital stay (LOS) compared with non-infected patients (median LOS: 18.9 d vs. 6 d for non-SSI patients). Patients with SSIs because of methicillin-resistant staphylococci incurred greater mean LOS compared with SSIs because of methicillin-sensitive organisms. Readmission rates reported in 11 studies indicate a greater likelihood in the presence of SSIs; comparison across studies was not feasible because of differences in data reporting. Consistent with increased healthcare resource utilization (LOS and readmission) associated with SSIs, cost studies (n = 23) revealed that the presence of SSIs was associated with up to three-fold cost increase compared with the absence of SSI across all orthopedic patient categories assessed.

CONCLUSIONS

SSIs are associated with increased morbidity, mortality rates, healthcare resource utilization, and costs. Despite the relatively low SSI incidence following orthopedic surgery and specifically arthroplasty, preventive methods, specifically those targeting S. aureus, would serve to minimize costs and improve patient outcomes.

Oritavancin Pharmacokinetics and Bone Penetration in Rabbits

The pharmacokinetics and bone concentrations of oritavancin were investigated after a single intravenous dose was administered to rabbits. The pharmacokinetic profile of oritavancin in rabbits showed that it is rapidly distributed to bone tissues, with concentrations remaining stable for up to 168 h, the last measured time point. Based on these findings, further evaluation of oritavancin for the treatment of infections in bone tissues is warranted.

Variation in the Type and Frequency of Postoperative Invasive Staphylococcus aureus Infections According to Type of Surgical Procedure

Objective.

To determine the epidemiological characteristics of postoperative invasive Staphylococcus aureus infection following 4 types of major surgical procedures.

Design.

Retrospective cohort study.

Setting.

Eleven hospitals (9 community hospitals and 2 tertiary care hospitals) in North Carolina and Virginia.

Patients.

Adults undergoing orthopedic, neurosurgical, cardiothoracic, and plastic surgical procedures.

Methods.

We used previously validated, prospectively collected surgical surveillance data for surgical site infection and microbiological data for bloodstream infection. The study period was 2003 through 2006. We defined invasive S. aureus infection as either nonsuperficial incisional surgical site infection or bloodstream infection. Nonparametric bootstrapping was used to generate 95% confidence intervals (CIs). P values were generated using the Pearson x2 test, Student t test, or Wilcoxon rank-sum test, as appropriate.

Results.

In total, 81,267 patients underwent 96,455 procedures during the study period. The overall incidence of invasive S. aureus infection was 0.47 infections per 100 procedures (95% CI, 0.43–0.52); 227 (51%) of 446 infections were due to methicillin-resistant S. aureus. Invasive S. aureus infection was more common after cardiothoracic procedures (incidence, 0.79 infections per 100 procedures [95% CI, 0.62–0.97]) than after orthopedic procedures (0.37 infections per 100 procedures [95% CI, 0.32–0.42]), neurosurgical procedures (0.62 infections per 100 procedures [95% CI, 0.53–0.72]), or plastic surgical procedures (0.32 infections per 100 procedures [95% CI, 0.17¬0.47]) (P < .001). Similarly, S. aureus bloodstream infection was most common after cardiothoracic procedures (incidence, 0.57 infections per 100 procedures [95% CI, 0.43–0.72]; P < .001, compared with other procedure types), comprising almost three-quarters of the invasive S. aureus infections after these procedures. The highest rate of surgical site infection was observed after neurosurgical procedures (incidence, 0.50 infections per 100 procedures [95% CI, 0.42–0.59]; P < .001, compared with other procedure types), comprising 80% of invasive S. aureus infections after these procedures.

Conclusion.

The frequency and type of postoperative invasive S. aureus infection varied significantly across procedure types. The highest risk procedures, such as cardiothoracic procedures, should be targeted for ongoing preventative interventions.

The use of surveillance and preventative measures for methicillin-resistant staphylococcus aureus infections in surgical patients

The Agency for Healthcare Research & Quality (AHRQ) found that Methicillin-resistant Staphylococcus aureus (MRSA) is associated with up to 375,000 infections and 23,000 deaths in the United States. It is a major cause of surgical site infections, with a higher mortality and longer duration of care than Methicillin-sensitive Staphylococcus aureus. A multifactorial bundled approach is needed to control this epidemic, with single interventions unlikely to have a significant impact on attenuating MRSA infection rates. Active surveillance has been studied in a wide range of surgical patients, including surgical intensive care and non-intensive care units; cardiac, vascular, orthopedic, obstetric, head and neck cancer and gastrostomy patients. There is sufficient evidence demonstrating a beneficial effect of surveillance and eradication prior to surgery to recommend its use on an expanded basis. Studies on MRSA surveillance in surgical patients that were published over the last 10 years were reviewed. In at least five of these studies, the MRSA colonization status of patients was reported to be a factor in preoperative antibiotic selection, with the modification of treatment regiments including the switching to vancomycin or teicoplanin in MRSA positive preoperative patients. Several authors also used decolonization protocols on all preoperative patients but used surveillance to determine the duration of the decolonization. Universal decolonization of all patients, regardless of MRSA status has been advocated as an alternative prevention protocol in which surveillance is not utilized. Concern exists regarding antimicrobial stewardship. The daily and universal use of intranasal antibiotics and/or antiseptic washes may encourage the promotion of bacterial resistance and provide a competitive advantage to other more lethal organisms. Decolonization protocols which indiscriminately neutralize all bacteria may not be the best approach. If a patient's microbiome is markedly challenged with antimicrobials, rebuilding it with replacement commensal bacteria may become a future therapy. Preoperative MRSA surveillance allows the selection of appropriate prophylactic antibiotics, the use of extended decolonization protocols in positive patients, and provides needed data for epidemiological studies.

A systematic review of animal models for Staphylococcus aureus osteomyelitis

Staphylococcus aureus (S. aureus) osteomyelitis is a significant complication for orthopaedic patients undergoing surgery, particularly with fracture fixation and arthroplasty. Given the difficulty in studying S. aureus infections in human subjects, animal models serve an integral role in exploring the pathogenesis of osteomyelitis, and aid in determining the efficacy of prophylactic and therapeutic treatments. Animal models should mimic the clinical scenarios seen in patients as closely as possible to permit the experimental results to be translated to the corresponding clinical care. To help understand existing animal models of S. aureus, we conducted a systematic search of PubMed and Ovid MEDLINE to identify in vivo animal experiments that have investigated the management of S. aureus osteomyelitis in the context of fractures and metallic implants. In this review, experimental studies are categorised by animal species and are further classified by the setting of the infection. Study methods are summarised and the relevant advantages and disadvantages of each species and model are discussed. While no ideal animal model exists, the understanding of a model's strengths and limitations should assist clinicians and researchers to appropriately select an animal model to translate the conclusions to the clinical setting.

Screening for methicillin-resistant Staphylococcus aureus: a comparative effectiveness review

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of health care-associated infections. Although the evidence in support of MRSA screening has been promising, a number of questions remain about the effectiveness of active surveillance.

METHODS

We searched the literature for studies that examined MRSA acquisition, MRSA infection, morbidity, mortality, harms of screening, and resource utilization when screening for MRSA carriage was compared with no screening or with targeted screening. Because of heterogeneity of the data and weaknesses in study design, meta-analysis was not performed. Strength of evidence (SOE) was determined using the system developed by the Grading of Recommendations Assessment, Development and Evaluation Working Group.

RESULTS

One randomized controlled trial and 47 quasi-experimental studies met our inclusion criteria. We focused on the 14 studies that addressed health care-associated outcomes and that attempted to control for confounding and/or secular trends, because those studies had the potential to support causal inferences. With universal screening for MRSA carriage compared with no screening, 2 large quasi-experimental studies found reductions in health care-associated MRSA infection. The SOE for this finding is low. For each of the other screening strategies evaluated, this review found insufficient evidence to determine the comparative effectiveness of screening.

CONCLUSIONS

Although there is low SOE that universal screening of hospital patients decreases MRSA infection, there is insufficient evidence to determine the consequences of universal screening or the effectiveness of other screening strategies.

A selected screening programme was less effective in the detection of methicillin-resistant Staphylococcus aureus colonisation in an orthopaedic unit

PURPOSE

Our unit has used a selective screening policy for methicillin-resistant Staphylococcus aureus (MRSA) colonisation using standard chromogenic growth media, based upon risk stratification. The aim of this study was to examine the effectiveness of this selective screening policy.

METHODS

A cohort of 429 patients was assessed for their risk status for MRSA colonisation using both rapid polymerase chain reaction (PCR) swabs and traditional culture and sensitivity analysis. The sensitivity, specificity, positive predictive values and negative predictive values of the traditional selective approach were calculated compared to universal rapid screening.

RESULTS

One hundred eighteen patients were considered high risk and would traditionally be further screened with standard culture of swabs. The prevalence of MRSA was 15/429 (3.5%). The sensitivity of selective screening was 53% identifying eight of 15 cases. The false-negative rate was therefore 47% and seven would have been missed. PCR results were available within four to six hours, whereas culture results were only available at 24 hours for the media showing no growth and not until 72 hours for positive MRSA cases.

CONCLUSIONS

We now advocate universal screening prior to, or on admission, using this rapid PCR test, as we consider this identifies MRSA colonisation more effectively and facilitates "ring-fencing" of orthopaedic beds.

Preoperative decolonization effective at reducing staphylococcal colonization in total joint arthroplasty patients

Staphylococcus decolonization prior to surgery is used to prevent surgical site infections (SSIs) after total joint arthroplasty (TJA). To determine if current treatment protocols result in successful decolonization of methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA), 106 consecutive patients were screened for nasal MSSA/MRSA colonization pre-operatively and on the day of surgery. Colonized patients used intranasal mupirocin twice a day and chlorhexidine showers daily 5 days prior to surgery. Pre-operatively, 24 joints (22.0%) were positive for MSSA colonization and 5 joints (4.6%) were positive for MRSA colonization. On the day of surgery, 3 joints (2.8%) who underwent decolonization were positive for MSSA colonization and 0 joints were positive for MRSA colonization. The reduction in MSSA colonization was significant (P<0.001), while the eradication of MRSA colonization approached statistical significance (P=0.063). Current decolonization protocols using intranasal mupirocin and chlorhexidine washes are effective for reducing MRSA/MSSA colonization.

Cost-benefit of infection control interventions targeting methicillin-resistant Staphylococcus aureus in hospitals: systematic review

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) incur significant costs. We aimed to examine the cost and cost-benefit of infection control interventions against MRSA and to examine factors affecting economic estimates. We performed a systematic review of studies assessing infection control interventions aimed at preventing spread of MRSA in hospitals and reporting intervention costs, savings, cost-benefit or cost-effectiveness. We searched PubMed and references of included studies with no language restrictions up to January 2012. We used the Quality of Health Economic Studies tool to assess study quality. We report cost and savings per month in 2011 US$. We calculated the median save/cost ratio and the save-cost difference with interquartile range (IQR) range. We examined the effects of MRSA endemicity, intervention duration and hospital size on results. Thirty-six studies published between 1987 and 2011 fulfilled inclusion criteria. Fifteen of the 18 studies reporting both costs and savings reported a save/cost ratio >1. The median save/cost ratio across all 18 studies was 7.16 (IQR 1.37-16). The median cost across all studies reporting intervention costs (n = 31) was 8648 (IQR 2025-19 170) US$ per month; median savings were 38 751 (IQR 14 206-75 842) US$ per month (23 studies). Higher save/cost ratios were observed in the intermediate to high endemicity setting compared with the low endemicity setting, in hospitals with <500-beds and with interventions of >6 months. Infection control intervention to reduce spread of MRSA in acute-care hospitals showed a favourable cost/benefit ratio. This was true also for high MRSA endemicity settings. Unresolved economic issues include rapid screening using molecular techniques and universal versus targeted screening.

Excess mortality and long-term disability from healthcare-associated staphylococcus aureus infections: a population-based matched cohort study

BACKGROUND

Staphylococcus aureus is a leading cause of healthcare-associated infections (HAIs), but the impact of S. aureus HAIs on the long-term survival and functional status of hospitalized patients remain unknown. This study aimed to examine whether S. aureus HAIs increase the risks for long-term mortality and disability.

METHODS

We conducted a retrospective population-based matched cohort study of inpatients at 8 medical centers, 43 regional hospitals, and 63 local hospitals which participated in the Taiwan Nosocomial Infection Surveillance (TNIS). We individually matched 3070 patients with S. aureus HAIs to 6140 inpatients without HAIs at a 1∶2 ratio by age, gender, hospital, specialty, underlying diseases, and the length of stay before onset of the S. aureus HAI. Main outcome measures are one-year excess risks for mortality, new-onset chronic ventilator dependence, and new-onset dialysis-dependent end-stage renal disease.

RESULTS

We found that patients with S. aureus HAIs had an excess one-year mortality of 20.2% compared with matched uninfected inpatients (P<0.001). The excess risk for new-onset chronic ventilator dependence and dialysis-dependent end-stage renal disease was 7.3% and 2.6%, respectively (Ps<0.001). S. aureus HAIs were also associated with an excess hospital stay of 12 days and an extra cost of $5978 (Ps<0.001).

CONCLUSION

S. aureus HAIs have substantial negative effect on the long-term outcome of hospitalized patients in terms of both mortality and disability, which should be taken into consideration in future cost-effectiveness studies of the control and prevention interventions for S. aureus HAIs.

Staphylococcus aureus screening and decolonization in orthopaedic surgery and reduction of surgical site infections

BACKGROUND

Staphylococcus aureus is the most common organism responsible for orthopaedic surgical site infections (SSIs). Patients who are carriers for methicillin-sensitive S. aureus or methicillin-resistant S. aureus (MRSA) have a higher likelihood of having invasive S. aureus infections. Although some have advocated screening for S. aureus and decolonizing it is unclear whether these efforts reduce SSIs.

QUESTIONS/PURPOSES

The purposes of this study were to determine (1) whether S. aureus screening and decolonization reduce SSIs in orthopaedic patients and (2) if implementing this protocol is cost-effective.

METHODS

Studies for this systematic review were identified by searching PubMed, which includes MEDLINE (1946-present), EMBASE.com (1974-present), and the Cochrane Library's (John Wiley & Sons) Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), Database of Abstracts of Reviews of Effects (DARE), Health Technology Assessment Database (HTAD), and the NHS Economic Evaluation Database (NHSEED). Comprehensive literature searches were developed using EMTREE, MeSH, and keywords for each of the search concepts of decolonization, MRSA, and orthopedics/orthopedic surgery. Studies published before 1968 were excluded. We analyzed 19 studies examining the ability of the decolonization protocol to reduce SSIs and 10 studies detailing the cost-effectiveness of S. aureus screening and decolonization.

RESULTS

All 19 studies showed a reduction in SSIs or wound complications by instituting a S. aureus screening and decolonization protocol in elective orthopaedic (total joints, spine, and sports) and trauma patients. The S. aureus screening and decolonization protocol also saved costs in orthopaedic patients when comparing the costs of screening and decolonization with the reduction of SSIs.

CONCLUSIONS

Preoperative screening and decolonization of S. aureus in orthopaedic patients is a cost-effective means to reduce SSIs.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies. See the Guidelines for Authors for a complete description of levels of evidence.

A perspective on the evidence regarding methicillin-resistant Staphylococcus aureus surveillance

Two prominent studies have been used by policy makers to prevent the enactment of standards of care regarding active surveillance of patients with methicillin-resistant Staphylococcus aureus in hospital settings. In this brief review and perspective of those studies, we contend that both studies have serious limitations (i.e., the intervention group was not given optimal intervention) that may not have been scrutinized by many policy makers, health officials, and other researchers. These studies seem to have had a disproportionate impact on health-care policy despite their limitations. Furthermore, health-care policy and treatment standards need to reflect the preponderance of evidence with appropriate weight given to research studies based on their strengths and limitations. Only then can treatment standards that are effective against methicillin-resistant Staphylococcus aureus be adopted or refuted.

Case report: artificial elevation of prothrombin time by telavancin

BACKGROUND

Methicillin-resistant Staphylococcus aureus infections are a well-documented risk of surgery and are becoming increasingly difficult to treat owing to continued acquired resistance. A new antibiotic for treatment of Staphylococcus aureus is telavancin.

CASE DESCRIPTION

A patient at our institution was prescribed telavancin for multiple spinal abscesses before spinal surgery. Routine preoperative testing revealed an international normalized ratio (INR) of 2.05 with no clear cause. Careful review of the patient's medication history and prescriber information revealed that telavancin may interfere with prothrombin time (PT/INR) testing. In vitro testing by our laboratory confirmed an association between telavancin dose and an increase in PT/INR. An alternative reagent for PT/INR testing unaffected by telavancin dose revealed a PT/INR of 0.97.

LITERATURE REVIEW

Telavancin interacts with artificial phospholipid surfaces used to monitor coagulation while having no actual effect on coagulation.

PURPOSES AND CLINICAL RELEVANCE

All physicians, especially orthopaedic surgeons, should be aware of the effects of telavancin and ensure proper measures are taken to acquire the true INR by switching the reagent used to test PT/INR or ensuring the PT/INR is drawn before telavancin dosing.

Low risk despite high endemicity of methicillin-resistant Staphylococcus aureus infections following elective total joint arthroplasty: a 12-year experience

Abstract Background. It is unknown if low rates of arthroplasty infections due to methicillin-resistant Staphylococcus aureus (MRSA) can be achieved in a setting with endemic MRSA (30%). Methods. We performed a 12-year prospective cohort study (1996-2008) of patients undergoing elective knee and hip joint arthroplasties with long-term follow-up. Retrospective MRSA surveillance was undertaken using electronic databases. Results. A total of 6,100 total joint arthroplasties (4001 hip; 2099 knee; 441 (7%) revisions) were monitored for a total of 34,281 person-years of follow-up (median 64 months). MRSA carriage was detected in 126 (2.1%) episodes before arthroplasty and in 147 (2.4%) after arthroplasty. Seven (0.11%) deep arthroplasty infections due to MRSA were retrieved for an overall incidence of 2 episodes per 10,000 person-years. Six were primary surgical site infections, while one infection resulted from endocarditis. MRSA colonization pressure was 11,411 MRSA-positive days for a total of 138,044 patient-days (8.3%) among all orthopedic patients. Conclusion. Institution-wide MRSA endemicity does not necessarily lead to a high MRSA infection risk after elective hip and knee arthroplasty.

Preoperative screening/decolonization for Staphylococcus aureus to prevent orthopedic surgical site infection: prospective cohort study with 2-year follow-up

We quantified surgical site infections (SSIs) after preoperative screening/selective decolonization before elective total joint arthroplasty (TJA) with 2-year follow-up and 2 controls. Concurrent controls (n = 2284) were patients of surgeons not participating in screening/decolonization. Preintervention controls (n = 741) were patients of participating surgeons who underwent TJA the previous year. Staphylococcus aureus nasal carriers (321/1285 [25%]) used intranasal mupirocin and chlorhexidine baths as outpatients. Staphylococcal SSIs occurred in no intervention patients (0/321) and 19 concurrent controls. If all SSIs occurred in carriers and 25% of controls were carriers, staphylococcal SSI rate would have been 3.3% in controls (19/571; P = .001). Overall SSI rate decreased from 2.7% (20/741) in preintervention controls to 1.2% (17/1440) in intervention patients (P = .009). Preoperative screening/selective decolonization was associated with fewer SSIs after elective TJA.

MRSA colonisation in patients with proximal femur fractures in a German trauma centre: incidence, infection rates and outcomes

PURPOSE

The aim of this study was to assess the incidence of methicillin-resistant Staphylococcus aureus (MRSA) colonisation in patients admitted into a level 1 German trauma centre with proximal femur fractures, to correlate this incidence with defined risk factors for MRSA colonisation and to determine its influence on morbidity and mortality.

METHODS

Between August and November 2006, 65 patients were included in the study. Cotton-tipped swab samples were taken from the nose, throat, groin and any skin defects in the emergency room. The following factors were recorded: age, gender, any concomitant diseases, the fracture type and treatment device, skin lesions, hospitalisation within the last year, any urinary or vascular catheters, a nasogastric or gastrostomy tube, an ileal stoma, the use of a respirator and antibiotic therapy within the last year. During follow-up, data concerning any surgical site infections; any chest, urinary or vascular catheter infections; the success of decontamination and death within 1 year after surgery were collected.

RESULTS

The risk factors for MRSA colonisation were positive in 40 patients. The incidence of MRSA colonisation was 17%, which is higher than in most comparable studies but consistent with some very recent publications. The nosocomial infection rates, surgical site infection rates and mortality within the 1-year follow-up period were significantly higher in the MRSA-colonised patients.

CONCLUSION

The high incidence of MRSA in this study supports the need for systematic detection of MRSA-colonised patients. In our hospital, any patient with positive risk factors for MRSA colonisation is swabbed in the emergency room and treated as MRSA positive until proven otherwise.

MRSA colonisation and subsequent risk of infection despite effective eradication in orthopaedic elective surgery

The objective of this study was to determine the effectiveness of screening and successful treatment of methicillin-resistant Staphylococcus aureus (MRSA) colonisation in elective orthopaedic patients on the subsequent risk of developing a surgical site infection (SSI) with MRSA.

We screened 5933 elective orthopaedic in-patients for MRSA at pre-operative assessment. Of these, 108 (1.8%) were colonised with MRSA and 90 subsequently underwent surgery. Despite effective eradication therapy, six of these (6.7%) had an SSI within one year of surgery. Among these infections, deep sepsis occurred in four cases (4.4%) and superficial infection in two (2.2%). The responsible organism in four of the six cases was MRSA. Further analysis showed that patients undergoing surgery for joint replacement of the lower limb were at significantly increased risk of an SSI if previously colonised with MRSA.

We conclude that previously MRSA-colonised patients undergoing elective surgery are at an increased risk of an SSI compared with other elective patients, and that this risk is significant for those undergoing joint replacement of the lower limb. Furthermore, when an infection occurs, it is likely to be due to MRSA.

Factors associated with variation in estimates of the cost of resistant infections

BACKGROUND

Existing estimates of the costs of antimicrobial resistance exhibit broad variability, and the contributing factors are not well understood. This study examines factors that contribute to variation in these estimates.

METHODS

Studies of the costs of resistant infections (1995-2009) were identified, abstracted, and stated in comparable terms (eg, converted to 2007 U.S. dollars). Linear regressions were conducted to assess how costs incurred by patients with resistant infections versus those incurred by uninfected or susceptible-organism-infected controls varied according to (1) costs incurred by control subjects; (2) study population characteristics; (3) methodological factors (eg, matching); and (4) length of stay.

RESULTS

Estimates of difference in costs incurred by patients with resistant infections versus patients without resistant infections varied between $-27,609 (control costs exceeded case costs) and $126,856. Differences were greater when the costs incurred by control subjects were higher (ie, when the underlying cost of care was high). Study-adjusted cost differences were greater for bloodstream infections (vs. any other infection site), for studies that reported median (vs. mean) costs, for studies that reported total (vs. postinfection or infection-associated) costs, for studies that used uninfected (vs. susceptible-organism-infected) controls, and for studies that did not match or adjust for length of stay before infection.

CONCLUSION

The cost of antimicrobial resistance seems to vary with the underlying cost of care. Increased costs of resistance are partially explained by longer length of stay for patients with resistant infections. Further research is needed to assess whether interventions should be differentially targeted at the highest cost cases.

The prevalence of meticillin-resistant Staphylococcus aureus in long-term care facilities: is there a need for tailored glycopeptide prophylaxis?

Prophylactic antibiotics are effective in reducing the rate of surgical site infection (SSI). Cephalosporin antibiotics are recommended except for patients colonised with meticillin resistant staphylococcus aureus (MRSA), where glycopeptide antibiotics are indicated. However, in the trauma setting, the MRSA status is unknown prior to surgery.

Aim: To determine if the incidence of MRSA colonisation in trauma patients from long term care (LTC) warrants the use of empirical glycopeptide antibiotics.

Methods: A retrospective analysis of patients admitted with hip fractures was performed. The MRSA status of patient from LTC facilities and home was determined.

Results: The prevalence of MRSA colonisation in patients admitted from LTC facilities was 33.6%, compared to 3.6% for patients admitted from home, P < 0.001.

Our results suggest that risk of patients carrying MRSA is significantly higher for patients being admitted form LTC. This group of patients may benefit from empirical glycopeptide antibiotic when the MRSA status is unknown.

Outcomes of revision total knee arthroplasty after methicillin-resistant Staphylococcus aureus infection

BACKGROUND

The incidence of infection by methicillin-resistant Staphylococcus aureus (MRSA) in total knee arthroplasty (TKA) is becoming a more frequent concern, as increased morbidity following TKA has been reported for infections by resistant organisms. This study investigates whether MRSA infections are associated with decreased functional scores.

QUESTIONS/PURPOSES

We therefore compared the functional scores, operative times, and rates of reinfection of revision TKA following MRSA infection versus other indications for revision.

METHODS

We retrospectively reviewed charts of 101 patients (103 knees) who underwent mobile bearing TKA revision from January 2003 to September 2006, with a minimum clinical followup of 2 years in 45 knees (44%). We obtained the following indices: WOMAC, Activities of Daily Living Score (ADLS), SF-36, and Knee Society scores (KSS). Three groups of revisions were compared: MRSA infection (n = 6), non-MRSA infection (n = 9), and aseptic failure (n = 30). The three groups were similar in demographics and comorbidities.

RESULTS

The MRSA (166 minutes) and non-MRSA groups (149 minutes) had longer operative times than the aseptic group (121 minutes). With numbers available, there were no differences in ROM, WOMAC, ADLS, KSS, and SF-36, with MRSA separate or combined with all infections. Infection recurrence between MRSA-infected knees and non-MRSA-infected knees was similar.

CONCLUSIONS

While our study was underpowered to detect functional differences between MRSA-infected knees and non-MRSA-infected knees it does add data to the literature. Knees revised for infection have longer operative times and more frequent infection after revision. The reason for increased operative times is unclear.

LEVEL OF EVIDENCE

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

Comparative effectiveness of antibiotics for the treatment of MRSA complicated skin and soft tissue infections

OBJECTIVE

With a growing number of studies and comparators in MRSA skin infections, a unified framework for comparing treatments is needed for health technology assessment (HTA). The objective was to systematically assess the success rates of common antimicrobial agents for the treatment of complicated skin and soft tissue infections (cSSTIs) caused by MRSA.

METHODS

MEDLINE, EMBASE, and Cochrane databases were searched to identify published clinical trials in which dalbavancin, daptomycin, linezolid, telavancin, teicoplanin, tigecycline, and vancomycin were used to treat cSSTIs. Pooled efficacy estimates were generated from clinical and microbiological determinations of success for the MRSA-subgroups in cSSTI clinical trials using a Bayesian meta-analytic approach. Success rates for each antibiotic were reported with 95% Bayesian confidence intervals (called credible intervals [CrI]). In sensitivity analyses the impact of different model parameters and article quality were investigated.

RESULTS

Out of 36 identified studies, 14 studies on six antibiotics with 28 treatment arms (n = 1840) were included in the analysis. No MRSA data in cSSTI were found for teicoplanin. The pooled success rate and CrI(95%) for each agent was: vancomycin (74.7%; CrI(95%): 64.1%-83.5%), dalbavancin (87.7%; CrI(95%): 74.6%-95.4%), linezolid (84.4%; CrI(95%): 76.6%-90.6%), telavancin (83.5%; CrI(95%): 73.6%-90.8%), daptomycin (78.1%; CrI(95%): 54.6%-93.2%) and tigecycline (70.4%; CrI(95%): 48.0%-87.6%). Comparisons between antibiotics suggested differences versus vancomycin for linezolid (+9.7%; CrI(95%): 4.4%-15.8%), dalbavancin (+13.1%; CrI(95%): 1.0%-23.8%), and telavancin (+8.8%; CrI(95%): 1.5-16.7%). The finding of lower vancomycin efficacy in MRSA cSSTI did not change in sensitivity analyses.

CONCLUSION

The results of this meta-analysis suggest higher success rates for linezolid and the new glycopeptides (dalbavancin and telavancin) in MRSA-confirmed cSSTIs. The uncertainty margins reflect the study limitations including number of cases and indirect nature of the comparisons. This example of Bayesian meta-analysis for MRSA cSSTI provides a potential framework for comparisons that is useful for HTA and formulary decision-making.

Staphylococcus aureus vaccine for orthopedic patients: an economic model and analysis

To evaluate the potential economic value of a Staphylococcus aureus vaccine for pre-operative orthopedic surgery patients, we developed an economic computer simulation model. At MRSA colonization rates as low as 1%, a $50 vaccine was cost-effective [<or=$50,000 per quality-adjusted life year (QALY) saved] at vaccine efficacy >or=30%, and a $100 vaccine at vaccine efficacy >or=70%. High MRSA prevalence (>or=25%) could justify a vaccine price as high as $1000. Our results suggest that a S. aureus vaccine for the pre-operative orthopedic population would be very cost-effective over a wide range of MRSA prevalence and vaccine efficacies and costs.

Evaluation of local MCP-1 and IL-12 nanocoatings for infection prevention in open fractures

The increasing incidence of bacterial infection and the appearance of Staphylococcus aureus (S. aureus) strains that are resistant to commonly used antibiotics has made it important to develop non-antibiotic approaches for infection prevention. The aim of this study was to develop local monocyte chemoattractant protein-1 (MCP-1) and interleukin-12 p70 (IL-12 p70) therapies to prevent S. aureus infection by enhancing the recruitment and activation of macrophages, which are believed to play an important role in infection prevention as the first line of defense against invading pathogens. Nanocoating systems for MCP-1 and IL-12 p70 deliveries were prepared, and their release characteristics desirable for infection prevention in open fractures were explored. Local MCP-1 therapy reduced S. aureus infection and influenced white blood cell populations, and local IL-12 p70 treatment had a more profound effect on preventing S. aureus infection. No synergistic relationship in decreasing S. aureus infection was observed when MCP-1 and IL-12 p70 treatments were combined. This reported new approach may reduce antibiotic use and antibiotic resistance.

Multilayer polypeptide nanoscale coatings incorporating IL-12 for the prevention of biomedical device-associated infections

Biomedical device-associated infection is one of the most common and problematic complications faced by millions of patients worldwide. The current antibiotic therapy strategies face challenges, the most serious of which is antibiotic resistance. Studies have shown that the systemic level of interleukin 12 (IL-12) decreases following major injuries resulting in decreased cell-mediated immune response. Here we report the development of IL-12 nanoscale coatings using electrostatic layer-by-layer self-assembly nanotechnology. We found that IL-12 nanoscale coatings at the implant/tissue interface substantially decrease infections in vivo, and IL-12 nanoscale coatings are advantageous over traditional treatments. This approach could be a revolutionary step toward preventing device-associated infections using a non-antibiotic approach.

Incidence of MRSA surgical-site infection in MRSA carriers in an orthopaedic trauma unit

We examined the incidence of infection with methicillin-resistant Staphylococcus aureus (MRSA) in patients admitted to the Leicester Royal Infirmary Trauma Unit between January 2004 and June 2006. The influence of MRSA status at the time of their admission was examined, together with age, gender and diagnosis, using multi-variant analysis. Of 2473 patients, 79 (3.2%) were MRSA carriers at the time of admission and 2394 (96.8%) were MRSA-negative. Those carrying MRSA at the time of admission were more likely to develop surgical site infection with MRSA (7 of 79 patients, 8.8%) than non-MRSA carriers (54 of 2394 patients, 2.2%, p < 0.001). Further analysis showed that hip fracture and increasing age were also risk factors with a linear increase in relative risk of 1.8% per year.

MRSA carriage at admission, age and the pathology are all associated with an increased rate of developing MRSA wound infection. Identification of such risk factors at admission helps to target health-care resources, such the use of glycopeptide antibiotics at induction and the ‘building-in’ of increased vigilance for wound infection pre-operatively.

Methicillin-resistant Staphylococcus aureus in orthopaedic trauma

We have conducted a case-control study over a period of ten years comparing both deep infection with methicillin-resistant staphylococcus aureus (MRSA) and colonised cases with a control group.

Risk factors associated with deep infection were vascular diseases, chronic obstructive pulmonary disease, admission to a high-dependency or an intensive-care unit and open wounds. Those for colonisation were institutional care, vascular diseases and dementia. Older age was a risk factor for any MRSA infection. The length of hospital stay was dramatically increased by deep infection.

These risk factors are useful in identifying higher-risk patients who may be more susceptible to MRSA infection. A strategy of early identification and isolation may help to control its spread in trauma units.

Patients' bath basins as potential sources of infection: a multicenter sampling study

BACKGROUND

Nosocomial infections are a marked burden on the US health care system and are linked to a high number of patient deaths.

OBJECTIVE

To identify and quantify bacteria in patients' bath basins and evaluate the basins as a possible reservoir for bacterial colonization and a risk factor for subsequent hospital-acquired infection.

METHODS

In a prospective study at 3 acute care hospitals, 92 bath basins, including basins from 3 intensive care units, were evaluated. Sterile culture sponges were used to obtain samples from the basins. The culture sponges were sent to an outside laboratory, and qualitative and quantitative microbial tests were conducted and the results reported.

RESULTS

Some form of bacteria grew in 98% of the samples (90 sponges), either by plating or on enrichment (95% confidence interval, 92%-99.7%). The organisms with the highest positive rates of growth on enrichment were enterococci (54%), gram-negative organisms (32%), Staphylococcus aureus (23%), vancomycin-resistant enterococci (13%), methicillin-resistant S aureus (8%), Pseudomonas aeruginosa (5%), Candida albicans (3%), and Escherichia coli (2%). Mean plate counts, in colony-forming units, were 10 187 for gram-negative organisms, 99 for E coli, 30 for P aeruginosa, 86 for S aureus, 207 for enterococci, and 31 for vancomycin-resistant enterococci.

CONCLUSIONS

Bath basins are a reservoir for bacteria and may be a source of transmission of hospital-acquired infections. Increased awareness of bath basins as a possible source of transmission of hospital-acquired infections is needed, particularly for high-risk patients.

Methicillin-resistant Staphylococcus aureus in orthopaedic surgery

Methicillin-resistant Staphylococcus aureus (MRSA) has become a ubiquitous bacterium in both the hospital and community setting. There are two major subclassifications of MRSA, community-acquired and healthcare-acquired, each with differing pathogenicity and management. MRSA is increasingly responsible for infections in otherwise healthy, active adults. Local outbreaks affect both professional and amateur athletes and there is increasing public awareness of the issue. Health-acquired MRSA has major cost and outcome implications for patients and hospitals. The increasing prevalence and severity of MRSA means that the orthopaedic community should have a basic knowledge of the bacterium, its presentation and options for treatment. This paper examines the evolution of MRSA, analyses the spectrum of diseases produced by this bacterium and presents current prevention and treatment strategies for orthopaedic infections from MRSA.

Surgical site infection, preoperative body washing and hair removal

Estimates suggest one in 20 patients develop an infection following surgery, costing the NHS around pounds 1bn each year (SSHAIP 2004). This article discusses surgical site infections and the commonest bacteria which cause them. It then explores two practices, preoperative body washing and preoperative hairremoval, and their effect on bacterial reduction and surgical site infection.