Clinical and financial outcomes due to methicillin resistant Staphylococcus aureus surgical site infection: a multi-center matched outcomes study

Methicillin-resistant Staphylococcus aureus in diabetic and non-diabetic foot infections

To identify the incidence of methicillin-resistant Staphylococcus aureus (MRSA) infection, reinfection and clinical outcomes. Four hundred forty-six patients that were admitted to the hospital with moderate or severe foot infections were retrospectively reviewed. Tissue and bone cultures were obtained from the index hospital admission. Conversion was defined as methicillin susceptible Staphylococcus aureus in the first culture and subsequently MRSA when there was a reinfection. The incidence of MRSA was 7.8% (n = 35), with no significant difference between soft tissue infections (7.7%) and osteomyelitis (8.0%). MRSA incidence was 9.4 times higher in non-diabetics (23.8% vs. 3.2%, p = <0.01). The incidence of reinfection was 40.8% (n = 182). Conversion to MRSA was seen in 2.2% (n = 4) total, occurring in 5.4%. Non-diabetics were 20.1 times more likely to have MRSA reinfection than people with diabetes (28.6% vs. 1.9%, p < 0.001). MRSA patients had a higher proportion of healed wounds (82.4% vs. 69.3%, p = 0.02). There were no differences in other clinical outcomes in MRSA vs. other infections in reinfection (28.6% vs. 24.3%, p = 0.11), amputation (48.6% vs. 52.0%, p = 0.69) or hospitalization (28.6% vs. 42.6, p = 0.11). The incidence of MRSA for the first infection (7.8%), reinfection (6.0%) and conversion to MRSA (2.2%) was low. MRSA was 9.4 times more common in people without diabetes.

Impact of spinal or epidural anaesthesia on perioperative outcomes in adult noncardiac surgery: a narrative review of recent evidence

Spinal and epidural anaesthesia and analgesia are important anaesthetic techniques, familiar to all anaesthetists and applied to patients undergoing a range of surgical procedures. Although the immediate effects of a well-conducted neuraxial technique on nociceptive and sympathetic pathways are readily observable in clinical practice, the impact of such techniques on patient-centred perioperative outcomes remains an area of uncertainty and active research. The aim of this review is to present a narrative synthesis of contemporary clinical science on this topic from the most recent 5-year period and summarise the foundational scholarship upon which this research was based. We searched electronic databases for primary research, secondary research, opinion pieces, and guidelines reporting the relationship between neuraxial procedures and standardised perioperative outcomes over the period 2018-2023. Returned citation lists were examined seeking additional studies to contextualise our narrative synthesis of results. Articles were retrieved encompassing the following outcome domains: patient comfort, renal, sepsis and infection, postoperative cancer, cardiovascular, and pulmonary and mortality outcomes. Convincing evidence of the beneficial effect of epidural analgesia on patient comfort after major open thoracoabdominal surgery outcomes was identified. Recent evidence of benefit in the prevention of pulmonary complications and mortality was identified. Despite mechanistic plausibility and supportive observational evidence, there is less certain experimental evidence to support a role for neuraxial techniques impacting on other outcome domains. Evidence of positive impact of neuraxial techniques is best established for the domains of patient comfort, pulmonary complications, and mortality, particularly in the setting of major open thoracoabdominal surgery. Recent evidence does not strongly support a significant impact of neuraxial techniques on cancer, renal, infection, or cardiovascular outcomes after noncardiac surgery in most patient groups.

Examining barriers to implementing a surgical-site infection bundle

BACKGROUND

Surgical-site infections (SSIs) can be catastrophic. Bundles of evidence-based practices can reduce SSIs but can be difficult to implement and sustain.

OBJECTIVE

We sought to understand the implementation of SSI prevention bundles in 6 US hospitals.

DESIGN

Qualitative study.

METHODS

We conducted in-depth semistructured interviews with personnel involved in bundle implementation and conducted a thematic analysis of the transcripts.

SETTING

The study was conducted in 6 US hospitals: 2 academic tertiary-care hospitals, 3 academic-affiliated community hospitals, 1 unaffiliated community hospital.

PARTICIPANTS

In total, 30 hospital personnel participated. Participants included surgeons, laboratory directors, clinical personnel, and infection preventionists.

RESULTS

Bundle complexity impeded implementation. Other barriers varied across services, even within the same hospital. Multiple strategies were needed, and successful strategies in one service did not always apply in other areas. However, early and sustained interprofessional collaboration facilitated implementation.

CONCLUSIONS

The evidence-based SSI bundle is complicated and can be difficult to implement. One implementation process probably will not work for all settings. Multiple strategies were needed to overcome contextual and implementation barriers that varied by setting and implementation climate. Appropriate adaptations for specific settings and populations may improve bundle adoption, fidelity, acceptability, and sustainability.

The effect of preoperative oral nutritional supplementation on surgical site infections among adult patients undergoing elective surgery: A systematic review and meta-analysis

INTRODUCTION

Mixed findings are reported on the effect of oral nutritional supplements in reducing Surgical Site Infections (SSIs).

MATERIAL AND METHODS

PubMED, EMBASE and Cochrane were searched. Studies from inception to July 2022 were included if they involved adults undergoing elective surgery and compared preoperative macronutrient oral nutritional supplements to placebo/standard diet.

RESULTS

Of 372 unique citations, 19 were included (N ​= ​2480): 13 RCTs (N ​= ​1506) and 6 observational studies (N ​= ​974). Moderate-certainty evidence suggested that nutritional supplements SSI risk (OR 0.54, 95% C.I. 0.40-0.72, N ​= ​2718 participants). In elective colorectal surgery, this risk-reduction was 0.43 (95% C.I. 0.26-0.61, N ​= ​835 participants) and among patients who received Impact 0.48 (95% C.I. 0.32-0.70, N ​= ​1338).

CONCLUSION

Oral nutritional supplements prior to adult elective surgery may significantly reduce SSIs, with an overall 50% protective effect. This protective effect persisted in subgroup analysis of colorectal surgery patients and the use of Impact.

MRSA Prophylaxis in Spine Surgery Decreases Postoperative Infections

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To compare infection rates before and after the implementation of a quality improvement protocol focused on methicillin-resistant Staphylococcus aureus (MRSA) screening and decolonization in patients undergoing lumbar fusion and/or decompression.

SUMMARY OF BACKGROUND DATA

Prior studies have demonstrated MRSA infections comprise a sizable portion of SSIs. Additional studies are required to improve our understanding of the risks and benefits of MRSA decolonization with vancomycin prophylaxis.

METHODS

A retrospective cohort analysis was conducted on patients who underwent spinal fusion or laminectomy before (2008-2011) and after (2013-2016) the implementation of an MRSA screening and treatment protocol. Odds ratios for MRSA, methicillin-sensitive Staphylococcus aureus (MSSA), and Vancomycin-resistant Enterococcus (VRE) infection before and after screening was calculated. Multivariate analysis assessed demographic characteristics as potential independent predictors of infection.

RESULTS

A total of 8425 lumbar fusion and 2558 lumbar decompression cases met inclusion criteria resulting in a total cohort of 10,983 patients. There was a significant decrease in the overall rate of infections ( P <0.001), MRSA infections ( P <0.001), and MSSA infections ( P <0.001) after protocol implementation. Although VRE infections after protocol implementation were not significantly different ( P =0.066), VRE rates as a percentage of all postoperative infections were substantially increased (0 vs. 3.36%, P =0.007). On multivariate analysis, significant predictors of the infection included younger age (OR=0.94[0.92-0.95]), shorter length of procedure (OR=1.00[0.99-1.00]), spinal fusion (OR=18.56[8.22-53.28]), higher ASA class (OR=5.49[4.08-7.44]), male sex (OR=1.61[1.18-2.20]), and history of diabetes (OR=1.58[1.08-2.29]).

CONCLUSION

The implemented quality improvement protocol demonstrated that preoperative prophylactically treating MRSA colonized patients decreased the rate of overall infections, MSSA infections, and MRSA infections. In addition, younger age, male sex, diabetic status, greater ASA scores, and spinal fusions were risk factors for postoperative infection.

Strategies to prevent surgical site infections in acute-care hospitals: 2022 Update

The intent of this document is to highlight practical recommendations in a concise format designed to assist acute-care hospitals in implementing and prioritizing their surgical-site infection (SSI) prevention efforts. This document updates the Strategies to Prevent Surgical Site Infections in Acute Care Hospitals published in 2014. This expert guidance document is sponsored by the Society for Healthcare Epidemiology of America (SHEA). It is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America (IDSA), the Association for Professionals in Infection Control and Epidemiology (APIC), the American Hospital Association (AHA), and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise.

Optimisation of perioperative procedural factors to reduce the risk of surgical site infection in patients undergoing surgery: a systematic review

Surgical site infections (SSI) are the leading cause of hospital readmission after surgical procedures with significant impact on post-operative morbidity and mortality. Modifiable risk factors for SSI include procedural aspects, which include the possibility of instrument contamination, the duration of the operation, the number of people present and the traffic in the room and the ventilation system of the operating theatre.The aim of this systematic review was to provide literature evidence on the relationship between features of surgical procedure sets and the frequency of SSI in patients undergoing surgical treatment, and to analyse how time frames of perioperative processes and operating theatre traffic vary in relation to the features of the procedure sets use, in order tooptimise infection control in OT. The results of the systematic review brought to light observational studies that can be divided into two categories: evidence of purely clinical significance and evidence of mainly organisational, managerial and financial significance. These two systems are largely interconnected, and reciprocally influence each other. The decision to use disposable devices and instruments has been accompanied by a lower incidence in surgical site infections and surgical revisions for remediation. A concomitant reduction in post-operative functional recovery time has also been observed. Also, the rationalisation of traditional surgical sets has also been observed in conjunction with outcomes of clinical significance.

Surgical Site Infections at Shirati KMT Hospital in Northeastern Tanzania

Despite improved guidelines for surgical practices and better surgical methods and tools, surgical site infection (SSI) is still a common cause of morbidity and mortality with increased rates in resource-limited nations. In Tanzania, there is limited data on SSI and associated risk factors for developing an effective surveillance system for SSI. In this study, we aimed to establish for the first time the baseline SSI rate and its associated factors at the Shirati KMT Hospital in Northeastern Tanzania. We collected hospital records of 423 patients who had undergone major and minor surgeries between January 1 and June 9, 2019, at the hospital. After accounting for incomplete records and missing information, we analyzed a total of 128 patients and found an SSI rate of 10.9% and performed univariate and multivariate logistic regression analyses for elucidating the relationship between risk factors and SSI. All patients with SSI had undergone major operations. Moreover, we observed trends of increased association of SSI with patients who are 40 or younger, female, and had received antimicrobial prophylaxis or more than one type of antibiotics. In addition, patients who had received an American Society of Anesthesiologists (ASA) score of II or III, as one category, or undergone elective operations or operations lasting longer than 30 minutes were prone to develop SSI. Although these findings were not statistically significant, both univariate and multivariate logistic regression analyses showed a significant correlation between clean contaminated wound class and SSI, consistent with previous reports. The study is the first to elucidate the rate of SSI and its correlated risk factors at the Shirati KMT Hospital. We conclude that, based on the obtained data, clean contaminated wound class is a significant predictor of SSI at the hospital and that an effective surveillance system for SSI should begin with adequate record keeping of all patients' hospitalization and an efficient follow-up system. Moreover, a future study should aim to explore more widespread SSI predictors such as premorbid illness, HIV status, duration of hospitalization prior to operation, and type of surgery.

Surgical Site Infection Prevention: A Review

IMPORTANCE

Approximately 0.5% to 3% of patients undergoing surgery will experience infection at or adjacent to the surgical incision site. Compared with patients undergoing surgery who do not have a surgical site infection, those with a surgical site infection are hospitalized approximately 7 to 11 days longer.

OBSERVATIONS

Most surgical site infections can be prevented if appropriate strategies are implemented. These infections are typically caused when bacteria from the patient's endogenous flora are inoculated into the surgical site at the time of surgery. Development of an infection depends on various factors such as the health of the patient's immune system, presence of foreign material, degree of bacterial wound contamination, and use of antibiotic prophylaxis. Although numerous strategies are recommended by international organizations to decrease surgical site infection, only 6 general strategies are supported by randomized trials. Interventions that are associated with lower rates of infection include avoiding razors for hair removal (4.4% with razors vs 2.5% with clippers); decolonization with intranasal antistaphylococcal agents and antistaphylococcal skin antiseptics for high-risk procedures (0.8% with decolonization vs 2% without); use of chlorhexidine gluconate and alcohol-based skin preparation (4.0% with chlorhexidine gluconate plus alcohol vs 6.5% with povidone iodine plus alcohol); maintaining normothermia with active warming such as warmed intravenous fluids, skin warming, and warm forced air to keep the body temperature warmer than 36 °C (4.7% with active warming vs 13% without); perioperative glycemic control (9.4% with glucose <150 mg/dL vs 16% with glucose >150 mg/dL); and use of negative pressure wound therapy (9.7% with vs 15% without). Guidelines recommend appropriate dosing, timing, and choice of preoperative parenteral antimicrobial prophylaxis.

CONCLUSIONS AND RELEVANCE

Surgical site infections affect approximately 0.5% to 3% of patients undergoing surgery and are associated with longer hospital stays than patients with no surgical site infections. Avoiding razors for hair removal, maintaining normothermia, use of chlorhexidine gluconate plus alcohol-based skin preparation agents, decolonization with intranasal antistaphylococcal agents and antistaphylococcal skin antiseptics for high-risk procedures, controlling for perioperative glucose concentrations, and using negative pressure wound therapy can reduce the rate of surgical site infections.

Tension Pneumocephalus Associated with Negative Pressure Wound Therapy with Instillation and Dwell Time for Methicillin-resistant Staphylococcus aureus Infection After Spinal Deformity Surgery

PURPOSE

Surgical site infection (SSI) is a serious complication after spine surgery. Recently, it has become possible to perform negative pressure wound therapy with instillation and dwell time (NPWTi-d) for postoperative infected wounds. We report the first rare case of symptomatic pneumoencephalopathy following NPWTi-d for methicillin-resistant Staphylococcus aureus (MRSA) infection after spinal deformity surgery.

METHODS

Retrospective review of a patient's medical record and imaging.

RESULTS

A 77-year-old female patient underwent posterior corrective fixation with no intraoperative complications. On the 10th postoperative day, SSI was diagnosed, and debridement was performed. Since MRSA was detected in the wound culture, and a prolonged inflammatory reaction was observed, NPWTi-d was started to preserve the instrumentation. Gradually, good granulation was observed, and the extensive soft tissue defect decreased. On the 29th day after the start of NPWTi-d, the patient experienced sudden headache and neck pain while standing, and head computed tomography led to the diagnosis of symptomatic pneumoencephalopathy. NPWTi-d was discontinued, and when surgery was performed to close the wound, dural injury was found, which was not present at the time of the initial surgery, and dural repair was performed. After 2 weeks of bed rest, the patient's pneumoencephalopathy improved. Three years have passed since the surgery, and no recurrence of cerebrospinal fluid leakage or infection has been observed.

CONCLUSIONS

Although NPWTi-d is a useful treatment for SSI, it is always necessary to pay attention to the development of pneumoencephalopathy and promptly diagnose and treat it because of the risk of life-threatening complications.

Fracture-related infection

Musculoskeletal trauma leading to broken and damaged bones and soft tissues can be a life-threating event. Modern orthopaedic trauma surgery, combined with innovation in medical devices, allows many severe injuries to be rapidly repaired and to eventually heal. Unfortunately, one of the persisting complications is fracture-related infection (FRI). In these cases, pathogenic bacteria enter the wound and divert the host responses from a bone-healing course to an inflammatory and antibacterial course that can prevent the bone from healing. FRI can lead to permanent disability, or long courses of therapy lasting from months to years. In the past 5 years, international consensus on a definition of these infections has focused greater attention on FRI, and new guidelines are available for prevention, diagnosis and treatment. Further improvements in understanding the role of perioperative antibiotic prophylaxis and the optimal treatment approach would be transformative for the field. Basic science and engineering innovations will be required to reduce infection rates, with interventions such as more efficient delivery of antibiotics, new antimicrobials, and optimizing host defences among the most likely to improve the care of patients with FRI.

Cost effectiveness of temporary isolation rooms in acute care settings in Singapore

Objectives

To estimate the change to health service costs and health benefits from a decision to adopt temporary isolation rooms that are effective at isolating the patient within a general ward environment. We assess the cost-effectiveness of a decision to adopt an existing temporary isolation room in a Singapore setting.

Method

We performed a model-based cost-effectiveness analysis to evaluate the impact of a decision to adopt temporary isolation rooms for infection prevention. We estimated changes to the costs from implementation, the number of cases of healthcare associated infection, acute care bed days used, they money value of bed days, the number of deaths, and the expected change to life years. We report the probability that adoption was cost-effective by the cost by life year gained, against a relevant threshold. Uncertainty is addressed with probabilistic sensitivity analysis and the findings are tested with plausible scenarios for the effectiveness of the intervention.

Results

We predict 478 fewer cases of HAI per 100,000 occupied bed days from a decision to adopt temporary isolation rooms. This will result in cost savings of $SGD329,432 and there are 1,754 life years gained. When the effectiveness of the intervention is set at 1% of cases of HAI prevented the incremental cost per life year saved is $16,519; below the threshold chosen for cost-effectiveness in Singapore.

Conclusions

We provide some evidence that adoption of a temporary isolation room is cost-effective for Singapore acute care hospitals. It is plausible that adoption is a positive decision for other countries in the region who may demonstrate fewer resources for infection prevention and control.

Incidence and Cost of Surgical Site Infections After Osteochondral Allograft Transplantation and Meniscal Allograft Transplantation in the Knee

Background:

Surgical site infections (SSIs) significantly influence outcomes and health care costs after orthopaedic surgery, but they have not been well characterized for osteochondral allograft (OCA) transplantation with or without meniscal allograft transplantation (MAT).

Purpose:

To characterize the incidence, cost, and risk factors associated with potential or confirmed SSIs after large single-surface, multisurface, or bipolar allograft transplantation in the knee.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

Prospectively collected registry data were analyzed for patients who underwent primary or revision OCA transplantation with or without MAT in the knee. The Centers for Disease Control and Prevention (CDC) guidelines were used to define SSIs and calculate the SSI incidence. Both potential and confirmed SSIs were analyzed to determine related treatment methods, calculate associated health care costs, and characterize risk factors based on the OCA surgery type (single-surface, multisurface, bipolar, ±MAT), American Society of Anesthesiologists physical status classification system, surgery duration, length of stay, age, sex, body mass index (BMI), and current tobacco use.

Results:

A total of 224 patients were included in the analysis. There were 2 SSIs in 1 patient that met CDC criteria, such that the incidence for this patient population was 0.9%. An additional 7 patients (3.1%) were examined for potential infections not classified as SSIs. Patients with potential or confirmed SSIs had a significantly higher mean BMI compared to patients with no evidence of an SSI ( P <.001). BMI >35 (odds ratio, 9.1) and tobacco use (odds ratio, 6.6) were associated with greater odds for a potential or confirmed SSI. The mean health care costs were $6101 for patients who required additional emergency room visits and/or irrigation and debridement within 90 days postoperatively for potential or confirmed SSIs, $19 for patients with potential superficial incisional SSIs, and $12,100 for patients who experienced a potential or confirmed deep incisional or organ/space SSI >90 days from surgery.

Conclusion:

Large OCA transplantation with and without MAT were associated with a low incidence of confirmed SSIs (0.9%), and patients with BMI >35 and current tobacco use had greater odds of an SSI. Potential and confirmed SSIs were associated with unscheduled appointments, additional surgical procedures, and higher costs.

Therapeutic evaluation of immunomodulators in reducing surgical wound infection

Despite many advances in infection control practices, including prophylactic antibiotics, surgical site infections (SSIs) remain a significant cause of morbidity, prolonged hospitalization, and death worldwide. Our innate immune system possesses a multitude of powerful antimicrobial strategies which make it highly effective in combating bacterial, fungal, and viral infections. However, pathogens use various stealth mechanisms to avoid the innate immune system, which in turn buy them time to colonize wounds and damage tissues at surgical sites. We hypothesized that immunomodulators that can jumpstart and activate innate immune responses at surgical sites, would likely reduce infection at surgical sites. We used three immunomodulators; fMLP (formyl-Methionine-Lysine-Proline), CCL3 (MIP-1α), and LPS (Lipopolysaccharide), based on their documented ability to elicit strong inflammatory responses; in a surgical wound infection model with Pseudomonas aeruginosa to evaluate our hypothesis. Our data indicate that one-time topical treatment with these immunomodulators at low doses significantly increased proinflammatory responses in infected and uninfected surgical wounds and were as effective, (or even better), than a potent prophylactic antibiotic (Tobramycin) in reducing P. aeruginosa infection in wounds. Our data further show that immunomodulators did not have adverse effects on tissue repair and wound healing processes. Rather, they enhanced healing in both infected and uninfected wounds. Collectively, our data demonstrate that harnessing the power of the innate immune system by immunomodulators can significantly boost infection control and potentially stimulate healing. We propose that topical treatment with these immunomodulators at the time of surgery may have therapeutic potential in combating SSI, alone or in combination with prophylactic antibiotics.

Surgical Site Infections

Surgical site infections (SSIs) are among the most common and most costly health care-associated infections, leading to adverse patient outcomes and death. Wound contamination occurs with each incision, but proven strategies exist to decrease the risk of SSI. In particular, improved adherence to evidence-based preventive measures related to appropriate antimicrobial prophylaxis can decrease the rate of SSI. Aggressive surgical debridement and effective antimicrobial therapy are needed to optimize the treatment of SSI.

Evaluation of the costing methodology of published studies estimating costs of surgical site infections: A systematic review

OBJECTIVES

Surgical site infections (SSIs) are associated with increased length of hospitalization and costs. Epidemiologists and infection control practitioners, who are in charge of implementing infection control measures, have to assess the quality and relevance of the published SSI cost estimates before using them to support their decisions. In this review, we aimed to determine the distribution and trend of analytical methodologies used to estimate cost of SSIs, to evaluate the quality of costing methods and the transparency of cost estimates, and to assess whether researchers were more inclined to use transferable studies.

METHODS

We searched MEDLINE to identify published studies that estimated costs of SSIs from 2007 to March 2021, determined the analytical methodologies, and evaluated transferability of studies based on 2 evaluation axes. We compared the number of citations by transferability axes.

RESULTS

We included 70 studies in our review. Matching and regression analysis represented 83% of analytical methodologies used without change over time. Most studies adopted a hospital perspective, included inpatient costs, and excluded postdischarge costs (borne by patients, caregivers, and community health services). Few studies had high transferability. Studies with high transferability levels were more likely to be cited.

CONCLUSIONS

Most of the studies used methodologies that control for confounding factors to minimize bias. After the article by Fukuda et al, there was no significant improvement in the transferability of published studies; however, transferable studies became more likely to be cited, indicating increased awareness about fundamentals in costing methodologies.

Management of superficial and deep surgical site infection: an international multidisciplinary consensus

Surgical site infections represent a considerable burden for healthcare systems. To obtain a consensus on the impact and future clinical and economic needs regarding SSI management in an era of multidrug resistance. A modified Delphi method was used to obtain consensus among experts from five European countries. The Delphi questionnaire was assembled by a steering committee, verified by a panel of experts and administered to 90 experts in 8 different surgical specialities (Abdominal, Cancer, Cardiac, General surgery, Orthopaedic, Thoracic, Transplant and Vascular and three other specialities (infectious disease, internal medicine microbiology). Respondents (n = 52) reached consensus on 62/73 items including that resistant pathogens are an increasing matter of concern and increase both treatment complexity and the length of hospital stay. There was strong positive consensus on the cost-effectiveness of early discharge (ED) programs, improvement of quality of life with ED and association between increased length of stay and economic burden to the hospital. However, established ED protocols were not widely available in their hospitals. Respondents expressed a positive consensus on the usefulness of antibiotics that allow ED. Surgeons are aware of their responsibility in an interdisciplinary team for the treatment of SSI, and of the impact of multidrug-resistant bacteria in the context of SSI. Reducing the length of hospital stays by applying ED protocols and implementing new treatment alternatives is crucial to reduce harm to patients and costs for the hospital.

Decolonization of Staphylococcus aureus

Staphylococcus aureus infections are associated with increased morbidity, mortality, hospital stay, and health care costs. S aureus colonization has been shown to increase risk for invasive and noninvasive infections. Decolonization of S aureus has been evaluated in multiple patient settings as a possible strategy to decrease the risk of S aureus transmission and infection. In this article, we review the recent literature on S aureus decolonization in surgical patients, patients with recurrent skin and soft tissue infections, critically ill patients, hospitalized non-critically ill patients, dialysis patients, and nursing home residents to inform clinical practice.

The economic impact of increased length of stay associated with surgical site infections in liver transplantation on Canadian healthcare costs

BACKGROUND

Complications after liver transplantation cause additional healthcare costs. The objective of this study was to contrast the length of stay (LOS) costs for recipients with and without surgical site infections (SSIs).

METHODS

This retrospective observational cohort study was conducted at a transplant center in Canada, between February 2011 and August 2014. The difference in the LOS costs was assessed by the Mann-Whitney U test, while multiple linear regression analysis was used to identify the variables that may have impacted on the costs.

RESULTS

Two hundred and twenty-nine liver transplant recipients were enrolled. Thirty-six recipients developed SSIs (36/229, 15.7%). The median LOS costs in recipients with and without SSIs were $39,456 Canadian dollars (interquartile range $25,696- 59,722) and $31,084 Canadian dollars (interquartile range $22,712-49 610), respectively (p = .072). There was a trend that the costs were higher for those recipients with versus those without SSIs (p = .088). Transfusion of ≥ 5 units of red cells and dialysis before transplantation impacted on cost.

CONCLUSION

There was a trend for higher healthcare facility costs for recipients with SSIs. Red cell transfusions and greater dialysis use before transplant were factors associated with the cost. Implementation of cost reduction strategies targeting high-cost recipients is necessary.

Early recognition and response to increases in surgical site infections using optimized statistical process control charts-the Early 2RIS Trial: a multicenter cluster randomized controlled trial with stepped wedge design

Background

Surgical site infections (SSIs) cause significant patient suffering. Surveillance and feedback of SSI rates is an evidence-based strategy to reduce SSIs, but traditional surveillance methods are slow and prone to bias. The objective of this cluster randomized controlled trial (RCT) is to determine if using optimized statistical process control (SPC) charts for SSI surveillance and feedback lead to a reduction in SSI rates compared to traditional surveillance.

Methods

The Early 2RIS Trial is a prospective, multicenter cluster RCT using a stepped wedge design. The trial will be performed in 29 hospitals in the Duke Infection Control Outreach Network (DICON) and 105 clusters over 4 years, from March 2016 through February 2020; year one represents a baseline period; thereafter, 8–9 clusters will be randomized to intervention every 3 months over a 3-year period using a stepped wedge randomization design. All patients who undergo one of 13 targeted procedures at study hospitals will be included in the analysis; these procedures will be included in one of six clusters: cardiac, orthopedic, gastrointestinal, OB-GYN, vascular, and spinal. All clusters will undergo traditional surveillance for SSIs; once randomized to intervention, clusters will also undergo surveillance and feedback using optimized SPC charts. Feedback on surveillance data will be provided to all clusters, regardless of allocation or type of surveillance. The primary endpoint is the difference in rates of SSI between the SPC intervention compared to traditional surveillance and feedback alone.

Discussion

The traditional approach for SSI surveillance and feedback has several major deficiencies because SSIs are rare events. First, traditional statistical methods require aggregation of measurements over time, which delays analysis until enough data accumulate. Second, traditional statistical tests and resulting p values are difficult to interpret. Third, analyses based on average SSI rates during predefined time periods have limited ability to rapidly identify important, real-time trends. Thus, standard analytic methods that compare average SSI rates between arbitrarily designated time intervals may not identify an important SSI rate increase on time unless the “signal” is very strong. Therefore, novel strategies for early identification and investigation of SSI rate increases are needed to decrease SSI rates. While SPC charts are used throughout industry and healthcare to improve and optimize processes, including other types of healthcare-associated infections, they have not been evaluated as a tool for SSI surveillance and feedback in a randomized trial.

Trial registration

ClinicalTrials.govNCT03075813, Registered March 9, 2017.

Healthcare resources attributable to methicillin-resistant Staphylococcus aureus orthopedic surgical site infections

The number of orthopedic surgeries is increasing as populations steadily age, but surgical site infection (SSI) rates remain relatively consistent. This study aimed to quantify the healthcare resources attributable to methicillin-resistant Staphylococcus aureus (MRSA) SSIs in orthopedic surgical patients. The analysis was conducted using a national claims database comprising data from almost all Japanese residents. We examined patients who underwent any of the following surgeries between April 2012 and March 2018: amputation (AMP), spinal fusion (FUSN), open reduction of fracture (FX), hip prosthesis (HPRO), knee prosthesis (KPRO), and laminectomy (LAM). Propensity score matching was performed to identify non-SSI control patients, and generalized estimating equations were used to estimate the differences in outcomes between the case and control groups. The numbers of MRSA SSI cases (infection rates) ranged from 64 (0.03%) to 1,152 (2.33%). MRSA SSI-attributable increases in healthcare expenditure ranged from $11,630 ($21,151 vs. $9,521) for LAM to $35,693 ($50,122 vs. $14,429) for FX, and increases in hospital stay ranged from 40.6 days (59.2 vs. 18.6) for LAM to 89.5 days (122.0 vs. 32.5) for FX. In conclusion, MRSA SSIs contribute to substantial increases in healthcare resource utilization, emphasizing the need to implement effective infection prevention measures for orthopedic surgeries.

Effectiveness of oral antibiotics for treating pyelonephritis caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae: A case series

BACKGROUND

Recently, the spread of multidrug-resistant bacteria has become a global problem. Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae (enterobacteria) is one example. The incidence of urinary tract infections caused by ESBL-producing enterobacteria has been increasing in some Japanese community settings. Currently, there is insufficient evidence on the effectiveness of oral antibiotics used for the treatment of pyelonephritis caused by ESBL-producing enterobacteria. We investigated the effectiveness of oral antibacterial agents against pyelonephritis caused by ESBL-producing Enterobacteriaceae.

METHODS

The records of patients who had been treated for pyelonephritis caused by ESBL-producing enterobacteria with oral antibiotics between April 1, 2014, and March 31, 2019, were reviewed retrospectively to assess the effectiveness of oral antibiotic treatment.

RESULTS

A total of seven cases were identified, including 1 patient with a positive blood culture and one patient with a Pitt bacteremia score of four points, indicating that the infections were severe. The antibiotics used to treat pyelonephritis were amoxicillin-clavulanic acid (n = 3), minocycline (n = 1), levofloxacin (n = 3), and sulfamethoxazole-trimethoprim with amoxicillin-clavulanic acid (n = 1). None of the patients had recurrence of pyelonephritis in the 60 days following oral antibiotic treatment, and there were no deaths during the 60-day follow-up period.

CONCLUSIONS

These antibiotics should be considered for oral treatment of pyelonephritis caused by ESBL-producing enterobacteria. However, as there is insufficient evidence available on the effectiveness of these antibiotics for the management of ESBL-producing enterobacterial infections, further large-scale prospective studies are needed.

Development and Evaluation of a Sensitive Bacteriophage-Based MRSA Diagnostic Screen

Engineered luciferase reporter bacteriophages provide specific, sensitive, rapid and low-cost detection of target bacteria and address growing diagnostic needs in multiple industries. Detection of methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization and antibiotic susceptibility play a critical supportive role in preventing hospital-acquired infections and facilitating antibiotic stewardship. We describe the development and evaluation of a novel phage-based MRSA diagnostic screen for nasal swab specimens. The screen utilizes two luciferase reporter phages capable of recognizing genetically-diverse Staphylococcus aureus. The beta-lactam antibiotic cefoxitin is included to differentiate between resistant (MRSA) and susceptible organisms. The screen positively identified 97.7% of 390 clinical MRSA isolates at low bacterial concentrations. At higher inoculums, 93.5% of 123 clinical non-MRSA Staphylococcus aureus yielded appropriate negative results. Although cross-reactivity of the phage cocktail was observed with other staphylococcal and bacillus species, these false positives were absent under selective conditions. MRSA remained detectable in the presence of 38 distinct competing species and was accurately identified in 100% of 40 spiked nasal specimens. Thus, this six-hour screen sensitively detected MRSA both in vitro and in human nasal matrix.

Development and challenges in setting up an international bone infection registry

INTRODUCTION

Osteomyelitis is an increasing burden on the society especially due to the emergence of multiple drug-resistant organisms. The lack of a central registry that prospectively collects data on patient risk factors, laboratory test results, treatment modalities, serological analysis results, and outcomes has hampered the research effort that could have improved and provided guidelines for treatments of bone infections. The current manuscript describes the lessons learned in setting up a multi-continent registry.

MATERIALS AND METHODS

This multicenter, international registry was conducted to prospectively collect essential patient, clinical, and surgical data with a 1-year follow-up period. Patients 18 years or older with confirmed S. aureus long bone infection through fracture fixation or arthroplasty who consented to participate in the study were included. The outcomes using the Short Form 36 Health Survey Questionnaire (version 2), Parker Mobility Score, and Katz Index of Independence in Activities of Daily Living were assessed at baseline and at 1 month, 6 months, and 12 months. Serological samples were collected at follow-ups.

RESULTS

Contract negotiation with a large number of study sites was difficult; obtaining ethics approvals were time-consuming but straightforward. The initial patient recruitment was slow, leading to a reduction of target patient number from 400 to 300 and extension of enrollment period. Finally, 292 eligible patients were recruited by 18 study sites (in 10 countries of 4 continents, Asia, North and South America, and Central Europe). Logistical and language barriers were overcome by employing courier service and local monitoring personnel.

CONCLUSIONS

Multicenter registry is useful for collecting a large number of cases for analysis. A well-defined data collection practice is important for data quality but challenging to coordinate with the large number of study sites.

Burden of Staphylococcus aureus infections after orthopedic surgery in Germany

BACKGROUND

This study assessed incidence, risk factors, and outcomes of Staphylococcus aureus infections (SAI) following endoprosthetic hip or knee, or spine surgeries.

METHODS

Adult patients with at least one of the selected surgeries from 2012 to 2015 captured in a German sickness fund database were included. SAI were identified using S. aureus-specific ICD-10 codes. Patients with certain prior surgeries and infections were excluded. Cumulative incidence and incidence density of post-surgical SAI were assessed. Risk factors, mortality, healthcare resource utilization and direct costs were compared between SAI and non-SAI groups using multivariable analyses over the 1 year follow-up.

RESULTS

Overall, 74,327 patients who underwent a knee (28.6%), hip (39.6%), or spine surgery (31.8%) were included. The majority were female (61.58%), with a mean age of 69.59 years and a mean Charlson Comorbidity Index (CCI) of 2.3. Overall, 1.92% of observed patients (20.20 SAI per 1000 person-years (PY)) experienced a SAI within 1 year of index hospitalization. Knee surgeries were associated with lower SAI risk compared with hip surgeries (Hazard Ratio (HR) = 0.8; p = 0.024), whereas spine surgeries did not differ significantly from hip surgeries. Compared with non-SAI group, the SAI group had on average 4.4 times the number of hospitalizations (3.1 vs. 0.7) and 7.7 times the number of hospital days (53.5 vs. 6.9) excluding the index hospitalization (p < 0.001). One year post-orthopedic mortality was 22.38% in the SAI and 5.31% in the non-SAI group (p < 0.001). The total medical costs were significantly higher in the SAI group compared to non-SAI group (42,834€ vs. 13,781€; p < 0.001). Adjusting for confounders, the SAI group had nearly 2 times the all-cause direct healthcare costs (exp(b) = 1.9; p < 0.001); and 1.72 times higher risk of death (HR = 1.72; p < 0.001).

CONCLUSIONS

SAI risk after orthopedic surgeries persists and is associated with significant economic burden and risk of mortality. Hence, risk reduction and prevention methods are of utmost importance.

Clinical and economic impact of methicillin-resistant Staphylococcus aureus: a multicentre study in China

Methicillin-resistant Staphylococcus aureus (MRSA) has become a serious threat to global health. In China, the proportion of S. aureus isolates that were MRSA was 44.6% in 2014. The clinical and economic impact of MRSA in China remains largely uninvestigated. This study aims to compare the differences in hospital costs, length of hospital stay, and hospital mortality rate between MRSA and methicillin-susceptible S. aureus (MSSA) colonization or infection and between MRSA cases and those without an S. aureus infection. A retrospective and multicentre study was conducted in four tertiary hospitals in China between 2013 and 2015. Inpatient characteristics and hospital costs were collected from electronic medical records. We conducted propensity score matching (PSM) to eliminate selection bias by balancing the potential confounding variables between the two groups. The main indicators included hospital costs, length of hospital stay, and hospital mortality rate. A total of 1,335 inpatients with MRSA, 1,397 with MSSA, and 33,606 without an S. aureus infection were included. PSM obtained 954 and 1,313 pairs between the MRSA and MSSA groups and between the MRSA and S. aureus-free groups, respectively. After PSM, MRSA colonization or infection is associated with an increased total hospital cost ranging from $3,220 to $9,606, an excess length of hospital stay of 6 days–14 days, and an attributable hospital mortality rate of 0–3.58%. Between the MRSA and MSSA groups, MRSA colonization or infection was significantly associated with a higher total hospital cost and longer length of hospital stay among survivors but not among non-survivors; however, there were no differences in the hospital mortality rate between these two groups. Between the MRSA and the S. aureus-free groups, MRSA colonization or infection was significantly associated with an increased total hospital cost, a prolonged length of hospital stay and a higher hospital mortality rate among both survivors and non-survivors. It is critical to quantify the clinical and economic impact of MRSA to justify resource allocation for the development of strategies to improve clinical outcomes and to reduce the economic burden.

Highlighting the gaps in quantifying the economic burden of surgical site infections associated with antimicrobial-resistant bacteria

Antibiotics are the pillar of surgery from prophylaxis to treatment; any failure is potentially a leading cause for increased morbidity and mortality. Robust data on the burden of SSI especially those due to antimicrobial resistance (AMR) show variable rates between countries and geographical regions but accurate estimates of the incidence of surgical site infections (SSI) due to AMR and its related global economic impact are yet to be determined. Quantifying the burden of SSI treatment is an incentive to sensitize governments, healthcare systems, and the society to invest in quality improvement and sustainable development. However in the absence of a unified epidemiologically sound infection definition of SSI and a well-designed global surveillance system, the end result is a lack of accurate and reliable data that limits the comparability of estimates between countries and the possibility of tracking changes to inform healthcare professionals about the appropriateness of implemented infection prevention and control strategies. This review aims to highlight the reported gaps in surveillance methods, epidemiologic data, and evidence-based SSI prevention practices and in the methodologies undertaken for the evaluation of the economic burden of SSI associated with AMR bacteria. If efforts to tackle this problem are taken in isolation without a global alliance and data is still lacking generalizability and comparability, we may see the future as a race between the global research efforts for the advancement in surgery and the global alarming reports of the increased incidence of antimicrobial-resistant pathogens threatening to undermine any achievement.

Using Core-genome Multilocus Sequence Typing to Monitor the Changing Epidemiology of Methicillin-resistant Staphylococcus aureus in a Teaching Hospital

Background

This study was performed to elucidate the changing epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in a Chinese teaching hospital.

Methods

We performed whole-genome sequencing and phylogenetic analysis on MRSA isolates recovered at Sir Run Run Shaw Hospital (SRRSH) from 2013 to 2015. MRSA isolates underwent susceptibility testing, resistance determinant screening, virulence assays and clinical data analysis.

Results

A total of 292 MRSA infections were identified during the study period. Of these, most belonged to sequence type (ST) 5 (51.4%; 150 of 292) and ST59 (23.3%; 68 of 292). The proportion of ST5 MRSA decreased from 68.3% in 2013 to 32.1% in 2015, and the proportion of ST59 MRSA increased from 8.9% to 41.0%. Core-genome phylogenetic analysis revealed that ST59 MRSA isolates exhibited wider genotypic diversity than ST5 MRSA isolates in both healthcare-onset and community-onset groups. Minimum spanning trees showed that a cluster of ST5 MRSA was circulating at SRRSH, whereas the ST59 MRSA infections were mostly sporadic. ST59 MRSA caused 45.2% of the 93 skin and soft-tissue infection cases and displayed lower levofloxacin (11.8%) and ciprofloxacin (19.1%) resistance rates than the ST239 and ST5 MRSA isolates. ST59 healthcare-onset MRSA displayed enhanced virulence in the skin infection model and hemolysis assays. Notably, these isolates had virulence levels similar to those of classic community-associated MRSA strains.

Conclusions

ST59 MRSA strains with high virulence potential have been replacing ST5 MRSA in predominance in SRRSH and causing nosocomial infections. Whole-genome sequencing is a powerful tool to monitor changes in the epidemiology of MRSA in hospitals.

Potential savings through single-dose intravenous Dalbavancin in long-term MRSA infection treatment - a health economic analysis using German DRG data

Complicated infections such as osteomyelitis, skin and soft tissue infections or endocarditis often require antibiotic therapies that can last up to several weeks. The prolonged hospital length of stay (LOS) leads to a dramatic increase in costs. Single-dose intravenous Dalbavancin is a novel antimicrobial agent for the treatment of acute bacterial skin, skin structure and soft tissue infections (ABSSSI) that allows an earlier discharge of patients, resulting in potential savings. Joint, bone and prostheses infections (JBPI) are also related with long LOS. The aim of this study is to determine the economic effects of single-dose intravenous Dalbavancin in suitable patients with Methicillin-resistant Staphylococcus aureus infections in Germany. For this purpose, an analysis with real-world patient treatment data was performed, which was subsequently validated in a large German hospital. In total, ABSSSI patients with MRSA infections could stay 6.45 days shorter and 2,865 € could be saved while JBPI patients could be discharged eventually 10.6 days earlier and 3,909 € could be saved. Single-dose intravenous Dalbavancin is thus an option for patients with ABSSSI and JBPI who are eligible for discharge.

Economic burden of antibiotic resistance in ESKAPE organisms: a systematic review

Background

Antibiotic resistance (ABR) is one of the biggest threats to global health. Infections by ESKAPE (Enterococcus, S. aureus, K. pneumoniae, A. baumannii, P. aeruginosa, and E. coli) organisms are the leading cause of healthcare-acquired infections worldwide. ABR in ESKAPE organisms is usually associated with significant higher morbidity, mortality, as well as economic burden. Directing attention towards the ESKAPE organisms can help us to better combat the wide challenge of ABR, especially multi-drug resistance (MDR).

Objective

This study aims to systematically review and evaluate the evidence of the economic consequences of ABR or MDR ESKAPE organisms compared with susceptible cases or control patients without infection/colonization in order to determine the impact of ABR on economic burden.

Methods

Both English-language databases and Chinese-language databases up to 16 January, 2019 were searched to identify relevant studies assessing the economic burden of ABR. Studies reported hospital costs (charges) or antibiotic cost during the entire hospitalization and during the period before/after culture among patients with ABR or MDR ESKAPE organisms were included. The costs were converted into 2015 United States Dollars. Disagreements were resolved by a third reviewer.

Results

Of 13,693 studies identified, 83 eligible studies were included in our review. The most studied organism was S. aureus, followed by Enterococcus, A. baumannii, E. coli, E. coli or/and K. pneumoniae, P. aeruginosa, and K. pneumoniae. There were 71 studies on total hospital cost or charge, 12 on antibiotic cost, 11 on hospital cost or charge after culture, 4 on ICU cost, 2 on hospital cost or charge before culture, and 2 on total direct and indirect cost. In general, ABR or MDR ESKAPE organisms are significantly associated with higher economic burden than those with susceptible organisms or those without infection or colonization. Nonetheless, there were no differences in a few studies between the two groups on total hospital cost or charge (16 studies), antibiotic cost (one study), hospital cost before culture (one study), hospital cost after culture (one study). Even, one reported that costs associated with MSSA infection were higher than the costs for similar MRSA cases.

Conclusions

ABR in ESKAPE organisms is not always, but usually, associated with significantly higher economic burden. The results without significant differences may lack statistical power to detect a significant association. In addition, study design which controls for severity of illness and same empirical antibiotic therapy in the two groups would be expected to bias the study towards a similar, even negative result. The review also highlights key areas where further research is needed.

The Cost Effectiveness of Single-Patient-Use Electrocardiograph Cable and Lead Systems in Monitoring for Coronary Artery Bypass Graft Surgery

Background: During admission for coronary artery bypass graft (CABG) surgery patients receive electrocardiograph (ECG) monitoring; for which reusable ECG cable and leads (rECG) are standard. Objective: Evaluate the cost effectiveness of a single-patient-use ECG cable and lead system (spECG). Methods: Review of the Medicare 2011-2014 database followed by a cost-effectiveness model considering a Medicare facility transitioning from rECG ($9 per patient) to spECG ($15). In-hospital ECG monitoring was for ≤8 days. In the model, patients underwent CABG and recovered in the intensive care unit, before transfer to the general ward and discharge. Surgical site infection (SSI) resulted in increased length of stay, readmission, or outpatient care. Health outcomes impacted EQ-5D-measured quality adjusted life years (QALYs). Health and cost outcomes were discounted at 3.5% annually. All costs in 2016 USD. Significance (95% level) was assessed via 2,000 simulations. Results: In 2014, 5.49% of patients had an SSI by 90-days post-surgery, with spECG reducing the odds of an SSI (odds ratio: 0.74, 0.62-0.89). Mean 40-year, per-patient costs to Medicare were $65,497 with rECG and $65,048 with spECG. The $450 saving was significant, with a median (95% credible interval) reduction of $466 ($174 to $989). Cost drivers were days required to treat inpatient SSIs. QALYs increases with spECG were significant but minor (median increase 0.008). Medicare savings may total $40 million per year with use of spECG. Conclusions: Post-operative SSI is a concern for Medicare patients undergoing CABG, and use of spECG is likely to provide cost and patient benefits.

Staphylococcus aureus nasal decolonization strategies: a review

Introduction: Staphylococcus aureus (S. aureus) infections are associated with increased morbidity, mortality and health-care costs. Persistent nasal carriage of S. aureus found in 10-30% of the general population, constitutes a risk factor for these infections. Nasal decolonization is one of the used strategies to prevent this risk in some situations. Areas covered: Mupirocin nasal ointment has been used for the nasal decolonization and prevention of staphylococcal infections in various settings like surgeries. However, rising rates of resistance to mupirocin require the development of new decolonization agents. In this review, we will discuss mupirocin, its origins, studies that proved its efficacy and the associated resistance, as well as other decolonization agents under investigation. Expert opinion: As some limitations exist to mupirocin use, further research for alternatives is encouraged. Some old approved antiseptics (chlorhexidine, povidone-iodine) or antibiotics (rifampicin, bacitracin) have been investigated for their efficacy in this indication. Other new agents (tea tree oil, retapamulin, LTX-109, XF-73, phages, lysostaphin, squalamine analogues, etc.) are being studied. Some of them are still in preclinical phases, and others have reached clinical trials, but further research is needed. Special interest should be given to single dose decolonization strategies and to molecules that do not select resistant strains.

Can Methicillin-resistant Staphylococcus aureus Silently Travel From the Gut to the Wound and Cause Postoperative Infection? Modeling the "Trojan Horse Hypothesis"

OBJECTIVE

To determine whether intestinal colonization with methicillin-resistant Staphylococcus aureus (MRSA) can be the source of surgical site infections (SSIs).

BACKGROUND

We hypothesized that gut-derived MRSA may cause SSIs via mechanisms in which circulating immune cells scavenge MRSA from the gut, home to surgical wounds, and cause infection (Trojan Horse Hypothesis).

METHODS

MRSA gut colonization was achieved by disrupting the microbiota with antibiotics, imposing a period of starvation and introducing MRSA via gavage. Next, mice were subjected to a surgical injury (30% hepatectomy) and rectus muscle injury and ischemia before skin closure. All wounds were cultured before skin closure. To control for postoperative wound contamination, reiterative experiments were performed in mice in which the closed wound was painted with live MRSA for 2 consecutive postoperative days. To rule out extracellular bacteremia as a cause of wound infection, MRSA was injected intravenously in mice subjected to rectus muscle ischemia and injury.

RESULTS

All wound cultures were negative before skin closure, ruling out intraoperative contamination. Out of 40 mice, 4 (10%) developed visible abscesses. Nine mice (22.5%) had MRSA positive cultures of the rectus muscle without visible abscesses. No SSIs were observed in mice injected intravenously with MRSA. Wounds painted with MRSA after closure did not develop infections. Circulating neutrophils from mice captured by flow cytometry demonstrated MRSA in their cytoplasm.

CONCLUSIONS

Immune cells as Trojan horses carrying gut-derived MRSA may be a plausible mechanism of SSIs in the absence of direct contamination.

The fight to keep resistance at bay, epidemiology of carbapenemase producing organisms (CPOs), vancomycin resistant enterococci (VRE) and methicillin resistant Staphylococcus aureus (MRSA) in Norway, 2006 - 2017

INTRODUCTION

Scandinavian countries have traditionally had a low prevalence of resistant organisms, but have in recent years experienced a change in their epidemiology. We aim to describe the epidemiology of carbapenemase-producing organisms (CPOs), vancomycin-resistant enterococci (VRE) and methicillin-resistant S. aureus (MRSA) in Norway, measure the importance of infections contracted abroad, and assess the morbidity and mortality associated with these resistant bacteria in Norway.

METHODS AND MATERIALS

We used data from the Norwegian surveillance system for communicable diseases covering all findings of the selected resistant bacteria including both infections and colonisation, in the period 2006-2017. Annual trends were assessed using negative binomial regression. For MRSA, we were able to calculate the Morisita-Horn index and transmission numbers following importation in order to assess the effect this had on further domestic transmission.

RESULTS

The incidence rates (per 100,000 personyears) of the three groups of resistant bacteria have increased during the period. In 2017 the incidence rates were 0.82 for CPOs, 7.09 for VRE and 43.8 for MRSA. 81% of CPO cases were diagnosed in hospitals, but 73% were infected abroad. Most VRE cases were infected in Norwegian hospitals, 85% were associated with hospitals outbreaks. MRSA was predominantly diagnosed in the community, only 21% were diagnosed in hospitals. Of all MRSA cases, 35% were infected in other countries. Most MRSA spa-types were not identified again after introduction, resulting in a transmission of MRSA equivalent to a mean of 0.30 persons infected from each spa-type identified (range: 0-22). The proportion of infections among all notified cases within each diagnose was 44% for MRSA, 9% for VRE and 45% for CPOs. Among persons notified with bacteraemia, the 30 days all-cause mortality were 20%, 16% and 50% for MRSA, VRE and CPOs respectively.

DISCUSSION

The incidence rates of CPOs, VRE and MRSA in Norway are low, but increasing. The continuing increase of notified resistant bacteria highlights the need for a revision of existing infection prevention and control guidelines.

The Cost of Surgical Site Infections after Colorectal Surgery in the United States from 2001 to 2012: A Longitudinal Analysis

Surgical site infections (SSIs) are among the most common types of postoperative complications in the United States and are associated with significant prevalence of morbidity and mortality in patients undergoing surgical interventions, especially in colorectal surgery (CRS) where SSI rates are significantly higher than those of similar operative sites. SSIs were identified from the National Inpatient Sample-Healthcare Cost and Utilization Project database from 2001 to 2012 based on the specification of an ICD-9 code. Propensity score matching was used to compare costs associated with SSI cases with those of non-SSI controls among elective and nonelective admissions. Results were projected nationally using Healthcare Cost and Utilization Project sampling methodology to evaluate the incidence of SSIs and ascertain the national cost burden retrospectively. Among 4,851,359 sample-weighted hospitalizations, 4.2 per cent (203,597) experienced SSI. Elective admissions associated with SSI-stayed hospitalized for an average of 7.8 days longer and cost $18,410 more than their counterparts who did not experience an SSI. Nonelective admissions that experienced an SSI had an 8.5-day longer hospital stay and cost $20,890 more than counterparts without perioperative infections. This represents a 3 per cent annual growth in costs for SSIs and seems to be largely driven by cost increases in treatment of SSIs for elective surgeries. Current efforts of SSI management after CRS focused on compliance with guidelines and tracking of infection rates would benefit from some improvements. Considering the growing costs and increase in resource utilization associated with SSIs from 2001 to 2012, further research on costs associated with management of SSIs specific to CRS is necessary.

Xpert MRSA screening in surgical patient flow; time for a rethink for hub-and-spoke laboratory models?

The move towards pathology networks and hub-and-spoke models of medical laboratory service provision has significantly changed the flow of samples, and the impact of results on patients, over recent years. At the same time advances in technology, including rapid, simple to use molecular platforms, are changing the way microbiology results can be utilized. Like many other medical microbiology laboratories, we struggle with this balance for many different sample types and test requests. Work published by Neilson et al. in Journal of Medical Microbiology last year looked at this balance for methicillin-resistant Staphylococcus aureus (MRSA) genotypic diagnostics and suggested significant cost savings when a whole-healthcare economy perspective was adopted. However, as with all changes, implementing MRSA molecular diagnostics in different clinical settings must be considered carefully. We add to this discussion in our accompanying letter, detailing our experience (in a hub-and-spoke medical microbiology laboratory setting) of 'rapid' MRSA molecular diagnostics for day-case surgery where pre-operative assessment had been missed, exploring the impact and costs of these tests. We find no impact on patient care, but at considerable additional cost. We hope this will add a cautionary note to those considering implementing molecular microbiology diagnostics, and reopen the debate on where, in hub-and-spoke laboratory models, such devices should be situated.

Staphylococcus aureus Nasal Colonization: An Update on Mechanisms, Epidemiology, Risk Factors, and Subsequent Infections

Up to 30% of the human population are asymptomatically and permanently colonized with nasal Staphylococcus aureus. To successfully colonize human nares, S. aureus needs to establish solid interactions with human nasal epithelial cells and overcome host defense mechanisms. However, some factors like bacterial interactions in the human nose can influence S. aureus colonization and sometimes prevent colonization. On the other hand, certain host characteristics and environmental factors can predispose to colonization. Nasal colonization can cause opportunistic and sometimes life-threatening infections such as surgical site infections or other infections in non-surgical patients that increase morbidity, mortality as well as healthcare costs.

Estimating excess length of stay due to healthcare-associated infections: a systematic review and meta-analysis of statistical methodology

BACKGROUND

Healthcare-associated infection (HCAI) affects millions of patients worldwide. HCAI is associated with increased healthcare costs, owing primarily to increased hospital length of stay (LOS) but calculating these costs is complicated due to time-dependent bias. Accurate estimation of excess LOS due to HCAI is essential to ensure that we invest in cost-effective infection prevention and control (IPC) measures.

AIM

To identify and review the main statistical methods that have been employed to estimate differential LOS between patients with, and without, HCAI; to highlight and discuss potential biases of all statistical approaches.

METHODS

A systematic review from 1997 to April 2017 was conducted in PubMed, CINAHL, ProQuest and EconLit databases. Studies were quality-assessed using an adapted Newcastle-Ottawa Scale (NOS). Methods were categorized as time-fixed or time-varying, with the former exhibiting time-dependent bias. Two examples of meta-analysis were used to illustrate how estimates of excess LOS differ between different studies.

FINDINGS

Ninety-two studies with estimates on excess LOS were identified. The majority of articles employed time-fixed methods (75%). Studies using time-varying methods are of higher quality according to NOS. Studies using time-fixed methods overestimate additional LOS attributable to HCAI. Undertaking meta-analysis is challenging due to a variety of study designs and reporting styles. Study differences are further magnified by heterogeneous populations, case definitions, causative organisms, and susceptibilities.

CONCLUSION

Methodologies have evolved over the last 20 years but there is still a significant body of evidence reliant upon time-fixed methods. Robust estimates are required to inform investment in cost-effective IPC interventions.

Population Pharmacokinetic Model for Vancomycin Used in Open Heart Surgery: Model-Based Evaluation of Standard Dosing Regimens

The purpose of this study was to investigate the population pharmacokinetics of vancomycin in patients undergoing open heart surgery. In this observational pharmacokinetic study, multiple blood samples were drawn over a 48-h period of intravenous vancomycin in patients who were undergoing open heart surgery. Blood samples were analyzed using an Architect i4000SR immunoassay analyzer. Population pharmacokinetic models were developed using Monolix 4.4 software. Pharmacokinetic-pharmacodynamic (PK-PD) simulations were performed to explore the ability of different dosage regimens to achieve the pharmacodynamic targets. A total of 168 blood samples were analyzed from 28 patients. The pharmacokinetics of vancomycin are best described by a two-compartment model with between-subject variability in clearance (CL), the volume of distribution of the central compartment (V₁), and volume of distribution of the peripheral compartment (V₂). The CL and the V₁ of vancomycin were related to creatinine CL (CL_CR), body weight, and albumin concentration. Dosing simulations showed that standard dosing regimens of 1 and 1.5 g failed to achieve the PK-PD target of AUC_0-24/MIC > 400 for an MIC of 1 mg/liter, while high weight-based dosing regimens were able to achieve the PK-PD target. In summary, the administration of standard doses of 1 and 1.5 g of vancomycin two times daily provided inadequate antibiotic prophylaxis in patients undergoing open heart surgery. The same findings were obtained when 15- and 20-mg/kg doses of vancomycin were administered. Achieving the PK-PD target required higher doses (25 and 30 mg/kg) of vancomycin.

Robotic Versus Open Renal Transplantation in Obese Patients: Protocol for a Cost-Benefit Markov Model Analysis

Background

Recent studies have reported a significant decrease in wound problems and hospital stay in obese patients undergoing renal transplantation by robotic-assisted minimally invasive techniques with no difference in graft function.

Objective

Due to the lack of cost-benefit studies on the use of robotic-assisted renal transplantation versus open surgical procedure, the primary aim of our study is to develop a Markov model to analyze the cost-benefit of robotic surgery versus open traditional surgery in obese patients in need of a renal transplant.

Methods

Electronic searches will be conducted to identify studies comparing open renal transplantation versus robotic-assisted renal transplantation. Costs associated with the two surgical techniques will incorporate the expenses of the resources used for the operations. A decision analysis model will be developed to simulate a randomized controlled trial comparing three interventional arms: (1) continuation of renal replacement therapy for patients who are considered non-suitable candidates for renal transplantation due to obesity, (2) transplant recipients undergoing open transplant surgery, and (3) transplant patients undergoing robotic-assisted renal transplantation. TreeAge Pro 2017 R1 TreeAge Software, Williamstown, MA, USA) will be used to create a Markov model and microsimulation will be used to compare costs and benefits for the two competing surgical interventions.

Results

The model will simulate a randomized controlled trial of adult obese patients affected by end-stage renal disease undergoing renal transplantation. The absorbing state of the model will be patients' death from any cause. By choosing death as the absorbing state, we will be able simulate the population of renal transplant recipients from the day of their randomization to transplant surgery or continuation on renal replacement therapy to their death and perform sensitivity analysis around patients' age at the time of randomization to determine if age is a critical variable for cost-benefit analysis or cost-effectiveness analysis comparing renal replacement therapy, robotic-assisted surgery or open renal transplant surgery. After running the model, one of the three competing strategies will result as the most cost-beneficial or cost-effective under common circumstances. To assess the robustness of the results of the model, a multivariable probabilistic sensitivity analysis will be performed by modifying the mean values and confidence intervals of key parameters with the main intent of assessing if the winning strategy is sensitive to rigorous and plausible variations of those values.

Conclusions

After running the model, one of the three competing strategies will result as the most cost-beneficial or cost-effective under common circumstances. To assess the robustness of the results of the model, a multivariable probabilistic sensitivity analysis will be performed by modifying the mean values and confidence intervals of key parameters with the main intent of assessing if the winning strategy is sensitive to rigorous and plausible variations of those values.

Acquisition and persistence of strain-specific methicillin-resistant Staphylococcus aureus and their determinants in community nursing homes

Background

Nursing home residents are frequently colonized with various strains of methicillin-resistant Staphylococcus aureus (MRSA) but the intra-facility dynamics of strain-specific MRSA remains poorly understood. We aimed at identifying and quantifying the associations between acquisition and carriage of MRSA strains and their potential risk factors in community nursing homes using mathematical modeling.

Methods

The data was collected during a longitudinal MRSA surveillance study in six nursing homes in South Central Wisconsin. MRSA cultures were obtained from subjects every 3 months for up to one year. MRSA isolates were subsequently strain-typed by pulsed-field gel electrophoresis (PFGE), and their genetic similarity was established based on the Dice coefficients. Bayesian network analysis, logistic regression and elastic net were used to quantify the associations between acquisition and carriage of MRSA strains discriminated at 80% and 95% strain similarity thresholds and potentially modifiable resident characteristics including previous antibiotic exposure, comorbidity, medical devices, chronic wounds, functional and cognitive status and recent hospitalizations.

Results

Absence of severe cognitive impairment as well as presence of a wound, device and severe comorbidity was associated with elevated probability of USA100 carriage although there was a variation based on the combination of those risk factors. Residents with severe comorbidity and cognitive status and presence of device and wound were identified as certain carriers of USA100 in our sample. Residents with a chronic wound were more likely to carry USA100 MRSA (OR = 2.77, 95% CI = 1.37–5.87). Functional status was identified as an important determinant of carriage of USA100 and USA300 strains. Comorbidity and cognitive status were the two factors associated with carriage of all clonal groups in the study (USA100, USA300 and USA1200).

Conclusions

The combination of Bayesian network analysis, logistic regression and elastic net can be used to identify associations between acquisition and carriage of MRSA strains and their potential risk factors in the face of scarce data. The revealed associations may be used to generate hypothesis for further study of determinants of acquisition and carriage of selected MRSA subtypes and to better inform infection control efforts in community nursing homes.

Electronic supplementary material

The online version of this article (10.1186/s12879-017-2837-3) contains supplementary material, which is available to authorized users.

Introduction to the Centers for Disease Control and Prevention and the Healthcare Infection Control Practices Advisory Committee Guideline for the Prevention of Surgical Site Infections

Surgical site infection (SSI) is a common type of health-care-associated infection (HAI) and adds considerably to the individual, social, and economic costs of surgical treatment. This document serves to introduce the updated Guideline for the Prevention of SSI from the Centers for Disease Control and Prevention (CDC) and the Healthcare Infection Control Practices Advisory Committee (HICPAC). The Core section of the guideline addresses issues relevant to multiple surgical specialties and procedures. The second procedure-specific section focuses on a high-volume, high-burden procedure: Prosthetic joint arthroplasty. While many elements of the 1999 guideline remain current, others warrant updating to incorporate new knowledge and changes in the patient population, operative techniques, emerging pathogens, and guideline development methodology.

Staphylococcus aureus Infections in German Patients with Type 2 Diabetes Mellitus after Orthopedic Surgery: Incidence, Risk Factors, and Clinical and Health-Economic Outcomes

BACKGROUND

This study assessed Staphylococcus aureus infection risk in patients with type 2 diabetes mellitus (T2DM) undergoing an orthopedic knee, hip, or spine surgery.

PATIENTS AND METHODS

All patients with a diagnosis of T2DM in the period from 2010 to 2012 were identified from a German claims database. First inpatient knee, hip, or spine surgery was used as index date. Cumulative incidence of S. aureus infections was calculated for several time intervals. Risk factors were identified based on a multi-variable Cox regression analysis. A case control analysis was conducted to assess mortality, healthcare resource utilization, and healthcare costs of S. aureus.

RESULTS

In total, 9,401 patients with T2DM underwent a knee, hip, or spine surgery. Mean age was 72.58 years, 63.32% were female, and 1.08% experienced an S. aureus infection in the 365-day follow-up period. The difference in all-cause direct treatment costs per patient-year between infected and non-infected patients was 24,437.50$. Mortality rates were 25.52% (S. aureus group) versus 5.22% (non-S. aureus group), based on a 365-day follow-up.

CONCLUSIONS

Staphylococcus aureus is associated with a substantial healthcare burden and high mortality. Effective infection control measures should be considered to reduce post-surgical S. aureus infection risk in patients with T2DM.

Creation and Evaluation of New Porcine Model for Investigation of Treatments of Surgical Site Infection

Surgical site infection (SSI) is the most common cause of surgical failure, increasing the risks of postoperative mortality and morbidity. Recently, it has been reported that the use of antimicrobial dressings at the incision site help with prevention of SSI. Despite the increased body of research on the development of different types of antimicrobial dressings for this application, to our knowledge, nobody has reported a reliable large animal model to evaluate the efficacy of developed materials in a preclinical SSI model. In this study, we developed a porcine full-thickness incision model to investigate SSI caused by methicillin-resistant Staphylococcus aureus (MRSA), the leading cause of SSI in the United States. Using this model, we then evaluated the efficacy of our newly developed silver releasing nanofibrous dressings for preventing and inhibiting MRSA infection. Our results confirmed the ease and practicality of a new porcine model as an in vivo platform for evaluation of biomaterials for SSI. Using this model, we found that our silver releasing scaffolds significantly reduced bacterial growth in wounds inoculated with MRSA relative to nontreated controls and to wounds treated with the gold standard, silver sulfadiazine, without causing inflammation at the wound site. Findings from this study confirm the potential of our silver-releasing nanofibrous scaffolds for treatment/prevention of SSI, and introduce a new porcine model for in vivo evaluation of additional SSI treatment approaches.