Risk factors for postoperative mediastinitis due to methicillin-resistant Staphylococcus aureus

Post-operative infections after cardiothoracic surgery and vascular procedures: a bibliometric and visual analysis of the 100 most-cited articles in the past 2 decades

Aim

To recognize and analyze the 100 most-cited articles on post-operative infections following cardiothoracic surgery and vascular procedures in the past 20 years.

Methods

Articles published on post-operative infections following cardiothoracic surgery and vascular procedures from inception 1986 till 2020 were reviewed and selected by two authors, based on their number of citations using the Scopus database. Their characteristics were recorded, i.e., title, authors, publication date, total no. of citations, citations per year (CPY), country of research, institutional affiliation, journal, research subject, and article type.

Results

The top 100 most influential articles were published between 1968 and 2017, with the peak in 2002. The mean number of total citations was 236.79 (range: 108-1,157). Areas with a medical focus were predominant in the studied research articles on the researched topic. The top-most journals in which these articles were published include Annals of Thoracic Surgery (14), followed by Circulation (8), and the New England Journal of Medicine (8). The number of publications affiliated with an institution were highest in the United States, with the Cleveland Clinic Foundation (6) having the most.

Conclusion

These findings highlight that there is a great potential to conduct research and publish the prevalence, causes, risk factors, pathogenesis and molecular biology of post-cardiac and -vascular surgery infections to prevent their adverse effects. The results can be taken into consideration for policy making to improve post-cardiac-surgery outcomes.

Risk factors for sternal wound infection after open-heart operations: A systematic review and meta-analysis

We aimed to quantitatively and systematically elucidate the rationality of the examined variables as independent risk factors for sternal wound infection. We searched databases to screen studies, ascertained the variables to be analysed, extracted the data and applied meta-analysis to each qualified variable. Odds ratios and mean differences were considered to be the effect sizes for binary and continuous variables, respectively. A random-effects model was used for these procedures. The source of heterogeneity was evaluated using a meta-regression. Publication bias was tested by funnel plot and Egger's test, the significant results of which were then calculated using trim and fill analysis. We used a sensitivity analysis and bubble chart to describe their robustness. After screening all variables in the eligible literature, we excluded 55 because only one or no research found them significant after multivariate analysis, leaving 33 variables for synthesis. Two binary variables (age over 65 years, NYHA class >2) and a continuous variable (preoperative stay) were not significant after the meta-analysis. The most robust independent risk factors in our study were diabetes mellitus, obesity, use of bilateral internal thoracic arteries, chronic obstructive pulmonary disease, prolonged surgery time, prolonged ventilation and critical preoperative state, followed by congestive heart failure, atrial fibrillation, renal insufficiency, stroke, peripheral vascular disease and use of an intra-aortic balloon pump. Relatively low-risk factors were emergent/urgent surgery, smoking, myocardial infarction, combined surgery and coronary artery bypass grafting. Sternal wound infection after open-heart surgery is a multifactorial disease. The detected risk factors significantly affected the wound healing process, but some were different in strength. Anything that affects wound healing and antibacterial ability, such as lack of oxygen, local haemodynamic disorders, malnutrition condition and compromised immune system will increase the risk, and this reminds us of comprehensive treatment during the perioperative period.

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.

Prevention, Diagnosis and Management of Post-Surgical Mediastinitis in Adults Consensus Guidelines of the Spanish Society of Cardiovascular Infections (SEICAV), the Spanish Society of Thoracic and Cardiovascular Surgery (SECTCV) and the Biomedical Research Centre Network for Respiratory Diseases (CIBERES)

This is a consensus document of the Spanish Society of Cardiovascular Infections (SEICAV), the Spanish Society of Thoracic and Cardiovascular Surgery (SECTCV) and the Biomedical Research Centre Network for Respiratory Diseases (CIBERES). These three entities have brought together a multidisciplinary group of experts that includes anaesthesiologists, cardiac and cardiothoracic surgeons, clinical microbiologists, infectious diseases and intensive care specialists, internal medicine doctors and radiologists. Despite the clinical and economic consequences of sternal wound infections, to date, there are no specific guidelines for the prevention, diagnosis and management of mediastinitis based on a multidisciplinary consensus. The purpose of the present document is to provide evidence-based guidance on the most effective diagnosis and management of patients who have experienced or are at risk of developing a post-surgical mediastinitis infection in order to optimise patient outcomes and the process of care. The intended users of the document are health care providers who help patients make decisions regarding their treatment, aiming to optimise the benefits and minimise any harm as well as the workload.

Type 2 diabetes mellitus and antibiotic-resistant infections: a systematic review and meta-analysis

BACKGROUND

Type 2 diabetes mellitus (T2DM) has been associated with infectious diseases; however, whether T2DM is associated with bacterial-resistant infections has not been thoroughly studied. We ascertained whether people with T2DM were more likely to experience resistant infections in comparison to T2DM-free individuals.

METHODS

Systematic review and random-effects meta-analysis. The search was conducted in Medline, Embase and Global Health. We selected observational studies in which the outcome was resistant infections (any site), and the exposure was T2DM. We studied adult subjects who could have been selected from population-based or hospital-based studies. I² was the metric of heterogeneity. We used the Newcastle-Ottawa risk of bias scale.

RESULTS

The search retrieved 3370 reports, 97 were studied in detail and 61 (449 247 subjects) were selected. Studies were mostly cross-sectional or case-control; several infection sites were studied, but mostly urinary tract and respiratory infections. The random-effects meta-analysis revealed that people with T2DM were twofold more likely to have urinary tract (OR=2.42; 95% CI 1.83 to 3.20; I² 19.1%) or respiratory (OR=2.35; 95% CI 1.49 to 3.69; I² 58.1%) resistant infections. Although evidence for other infection sites was heterogeneous, they consistently suggested that T2DM was associated with resistant infections.

CONCLUSIONS

Compelling evidence suggests that people with T2DM are more likely to experience antibiotic-resistant urinary tract and respiratory infections. The evidence for other infection sites was less conclusive but pointed to the same overall conclusion. These results could guide empirical treatment for patients with T2DM and infections.

Eradication of Staphylococcus aureus post-sternotomy mediastinitis following the implementation of universal pre-operative nasal decontamination with mupirocin: an interrupted time-series analysis

BACKGROUND

Although pre-surgical nasal decontamination with mupirocin (NDM) has been advocated as a measure for preventing post-surgical mediastinitis (PSM) due to Staphylococcus aureus, this strategy is not universally recommended due to the lack of robust supporting evidence. We aimed to evaluate the role of pre-operative NDM in the annual incidence of S. aureus PSM at our institution.

METHODS

An interrupted time-series analysis, with autoregressive error model, was applied to our single-center cohort by comparing pre-intervention (1990-2003) and post-intervention period (2005 to 2018). Logistic regression was performed to analyze risk factors for S. aureus PSM.

FINDINGS

12,236 sternotomy procedures were analyzed (6,370 [52.1%] and 5,866 [47.9%] in the pre-intervention and post-intervention periods, respectively). The mean annual percentage adherence to NDM estimated over the post-interventional period was 90.2%. Only four out of 127 total cases of S. aureus PSM occurred during the 14-years post-intervention period (0.68/1,000 sternotomies vs. 19.31/1,000 in pre-interventional period [p<0.0001]). Interrupted time-series analysis demonstrated a statistically significant annual reduction of S. aureus PSM trend of -9.85 cases per 1,000 sternotomies (-13.17 to -6.5, P-value< 0·0001) in 2005, with a decreasing trend maintained over the following five years with an estimated relative reduction of 84.8% (95% CI: 89·25 to 74·09). Chronic obstructive pulmonary disease was the single independent risk factor for S. aureus PSM (odds ratio: 3.7; 95% CI: 1.72-7.93) and was equally distributed in patients undergoing sternotomy during pre or post-intervention periods.

INTERPRETATION

Our experience suggests that the implementation of pre-operative NDM reduces significantly the incidence of S. aureus PSM.

Impact of BMI on Complications and Satisfaction in Patients With Papillary Thyroid Cancer and Lateral Neck Metastasis

BACKGROUND

This study investigates the effect of body mass index (BMI) on complications and satisfaction in patients who underwent thyroidectomy and lateral neck dissection.

METHODS

We retrospectively reviewed 386 patients with papillary thyroid cancer who underwent total thyroidectomy and lateral neck dissection between January 2013 and December 2016. We compared variables including population characteristics, subjective satisfaction, and complications in nonobese (BMI < 28.0 kg/m²) and obese (BMI ≥ 28.0 kg/m²) patients.

RESULTS

Obesity was associated with an increased risk of postoperative hemorrhage (POH) (P = .014), accessory nerve injury (P < .001), operative time (P < .001) and infection (P = .013). However, obese patients had higher subjective satisfaction and Vancouver Scar Scale (VSS) scores (P < .05).

CONCLUSIONS

Obesity was associated with increased risk of POH, injury of the SAN, and infection. Interestingly, we found that obese patients had higher subjective satisfaction and VSS scores.

Evaluation of treatment options for methicillin-resistant Staphylococcus aureus infections in the obese patient

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a major cause of infection in both the hospital and community setting. Obesity is a risk factor for infection, and the prevalence of this disease has reached epidemic proportions worldwide. Treatment of infections in this special population is a challenge given the lack of data on the optimal antibiotic choice and dosing strategies, particularly for treatment of MRSA infections. Obesity is associated with various physiological changes that may lead to altered pharmacokinetic parameters. These changes include altered drug biodistribution, elimination, and absorption. This review provides clinicians with a summary of the literature pertaining to the pharmacokinetic and pharmacodynamic considerations when selecting antibiotic therapy for the treatment of MRSA infections in obese patients.

Antibacterial Prophylaxis for Surgical Site Infection in the Elderly: Practical Application

Surgical site infections are among the most common healthcare-associated infections and are linked with increased length of hospitalization, re-admission, mortality and significant financial burden. Risk factors for the occurrence of surgical site infections include variables related to the surgical procedure as well as host factors. Increasing age is associated with the occurrence of surgical site infections. The aim of this review is to give an update on the antibiotic prophylaxis for surgical site infection in elderly people. We focused on specific issues and practical applications, such as the importance of targeting the antimicrobial agent to the susceptibility pattern of colonizing flora in selected cases and the need for dosage modifications.

European Association for Cardio-Thoracic Surgery expert consensus statement on the prevention and management of mediastinitis

Mediastinitis continues to be an important and life-threatening complication after median sternotomy despite advances in prevention and treatment strategies, with an incidence of 0.25-5%. It can also occur as extension of infection from adjacent structures such as the oesophagus, airways and lungs, or as descending necrotizing infection from the head and neck. In addition, there is a chronic form of 'chronic fibrosing mediastinitis' usually caused by granulomatous infections. In this expert consensus, the evidence for strategies for treatment and prevention of mediatinitis is reviewed in detail aiming at reducing the incidence and optimizing the management of this serious condition.

[Rational antibiotic treatment of mediastinitis]

Mediastinitis occurs as a severe complication of thoracic and cardiac surgical interventions and is the result of traumatic esophageal perforation, conducted infections or as a result of lymphogenic and hematogenic spread of specific infective pathogens. Treatment must as a rule be accompanied by antibiotics, whereby knowledge of the spectrum of pathogens depending on the pathogenesis is indispensable for successful antibiotic therapy. Polymicrobial infections with a high proportion of anaerobes are found in conducted infections of the mediastinum and after esophageal perforation. After cardiac surgery Staphylococci are the dominant pathogens and a nasal colonization with Staphylococcus aureus seems to be a predisposing risk factor. Fungi are the predominant pathogens in immunocompromised patients with consumptive underlying illnesses and can cause acute or chronic forms with granulomatous inflammation. Resistant pathogens are increasingly being found in high-risk patient cohorts, which must be considered for a calculated therapy. For calculated antibiotic therapy the administration of broad spectrum antibiotics, mostly beta-lactams alone or combined with metronidazole is the therapy of choice for both Gram-positive and Gram-negative bacteria inclusive of anaerobes. For patients at risk, additional antibiotic classes with a spectrum against methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE) can be administered. Increasing rates of multidrug-resistant Gram-negative bacteria (e.g. Enterobacteriaceae) and non-fermenting bacteria (e.g. Pseudomonas and Acinetobacter) in individual cases necessitates the use of polymyxins (e.g. colistin), new tetracyclines (e.g. glycylglycines) and newly developed combinations of beta-lactams and beta-lactam inhibitors. For treatment of fungal infections (e.g. Candida, Aspergillus and Histoplasma) established and novel azoles, amphotericin B and echinocandins seem to be successful; however, detection of Candida, particularly in mixed infections does not always necessitate treatment. Mediastinitis is still a severe infectious disease with a high mortality, which necessitates an early and broad spectrum antibiotic therapy; however, with respect to optimal duration of therapy and selection of antibiotics, data from good quality comparative studies are lacking.

Strategies to Prevent Surgical Site Infections in Acute Care Hospitals: 2014 Update

Previously published guidelines are available that provide comprehensive recommendations for detecting and preventing healthcare-associated infections (HAIs). 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 “Strategies to Prevent Surgical Site Infections in Acute Care Hospitals,” published in 2008. This expert guidance document is sponsored by the Society for Healthcare Epidemiology of America (SHEA) and is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America (IDSA), the American Hospital Association (AHA), the Association for Professionals in Infection Control and Epidemiology (APIC), and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise. The list of endorsing and supporting organizations is presented in the introduction to the 2014 updates.

Deep sternal wound infection after cardiac surgery: Evidences and controversies

Despite many advances in prevention and perioperative care, deep sternal wound infection (DSWI) remains a pressing concern in cardiac surgery, with a still relevant incidence and with a considerable impact on in-hospital mortality and also on mid- and long-term survival. The permanent high impact of this complication is partially related to the increasing proportion of patients at high-risk for infection, as well as to the many patient and surgical risk factors involved in the pathogenesis of DSWI. The prophylactic antibiotic therapy is one of the most important tools in the prevention of DSWI. However, the choice of antibiotic, the dose, the duration, the adequate levels in serum and tissue, and the timing of antimicrobial prophylaxis are still controversial. The treatment of DSWI ranges from surgical revision with primary closure to surgical revision with open dressings or closed irrigation, from reconstruction with soft tissue flaps to negative pressure wound therapy (NPWT). However, to date, there have been no accepted recommendations regarding the best management of DSWI. Emerging evidence in the literature has validated the efficacy and safety of NPWT either as a single-line therapy, or as a “bridge” prior to final surgical closure. In conclusion, the careful control of patient and surgical risk factors - when possible, the proper antimicrobial prophylaxis, and the choice of validated techniques of treatment could contribute to keep DSWIs at a minimal rate.

Decolonisation of MRSA and its effect on surgical site infections--a study in a tertiary care institute

BACKGROUND

Two-thirds of surgical site infections (SSI) because of Staphylococcus aureus are caused by Methicillin resistant Staphylococcus aureus (MRSA). This study was done to assess the efficacy of topical 2% mupirocin with 2% chlorhexidine gluconate body wash in decolonizing MRSA and its impact in preventing SSI because of MRSA. The various risk factors associated with MRSA carriers and SSI were also studied because of paucity of data in the developing world.

METHODS

We did a non-randomised interventional trial in 602 patients undergoing elective general surgical operations. All patients in case (297) group were screened for MRSA and those positive were decolonised with topical 2% mupirocin calcium ointment and daily baths with 2% chlorhexidine antiseptic solution for 5 days. Control (305) group patients underwent surgery without decolonisation. Postoperatively, all patients were followed up for SSI for 30 days.

RESULTS

Prevalence of MRSA carriers was 7.5% with decolonisation rate of 95.2%. The SSI incidence was 21.3%. The significant risk factors for SSI were type of anaesthesia (p = 0.002), duration of surgery (p = 0.001) and preoperative hospital stay (p = 0.001). There was a significant association between MRSA carrier positivity at the time of surgery and SSI (p = 0.041).

CONCLUSIONS

There was no reduction in rate of SSI or other nosocomial infections in patients undergoing elective general surgical operations following preoperative MRSA decolonisation with 2% mupirocin and 2% chlorhexidine gluconate in MRSA carriers. MRSA carrier status was a significant risk factor for SSI but not for other nosocomial infections.

The combined use of NPWT and instillation using an octenidine based wound rinsing solution: a case study

Effective wound bed preparation is an essential element in the healing of chronic wounds, including pressure ulcers (PUs). Negative pressure wound therapy (NPWT) reduces oedema, stimulates the formation of granulation tissue and helps remove wound exudate. This helps prepare the wound bed for secondary healing, skin grafting or coverage with flaps. Combining NPWT with an instillation phase using an antiseptic (octenidine based) irrigation solution is a novel approach to PU management. Three patients with Category 4 gluteal PUs were treated with NPWT and instillation fluid, following surgical debridement of necrotic tissue. The aim was to achieve optimal wound bed preparation prior to wound closure by local fasciocutaneous flap. The antiseptic efficacy of octenilin wound irrigation solution in microorganism eradication was quantified by in vitro tests simulating real conditions using leg ulcer vacuum exudates. All wounds completely healed after four weeks, and no adverse incidents occurred due to instillation of octenidine. No recurrence of the PU occurred during a one year follow-up.

Treatment of mediastinitis due to methicillin-resistant Staphylococcus aureus in a renal dysfunction patient undergoing adjustments to the linezolid dose

This study is the first case report of the treatment of methicillin-resistant Staphylococcus aureus (MRSA) mediastinitis using therapeutic drug monitoring of the serum and wound exudate concentrations of linezolid in a renal dysfunction patient. In the present study, the serum trough concentration of linezolid was maintained between 2 and 7 μg/mL. Therapeutic drug monitoring dosage adjustments may be especially useful in patients with renal dysfunction and severe MRSA infection.

Evaluation of fever and infections in cardiac surgery patients

Fever following cardiac surgery is common and may be infectious or noninfectious in etiology. In this article, we review the major causes of postoperative fever while highlighting special considerations in cardiac surgery patients. We also outline a structured approach to evaluation and present an overview of diagnostic and management considerations for mediastinitis, postpericardiotomy syndrome, prosthetic valve endocarditis, aortic vascular graft infections, and ventricular assist device infections.

Strategies to prevent surgical site infections in acute care hospitals: 2014 update

Previously published guidelines are available that provide comprehensive recommendations for detecting and preventing healthcare-associated infections (HAIs). 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 “Strategies to Prevent Surgical Site Infections in Acute Care Hospitals,”1 published in 2008. This expert guidance document is sponsored by the Society for Healthcare Epidemiology of America (SHEA) and is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America (IDSA), the American Hospital Association (AHA), the Association for Professionals in Infection Control and Epidemiology (APIC), and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise. The list of endorsing and supporting organizations is presented in the introduction to the 2014 updates.2

Ceftobiprole medocaril is an effective treatment against methicillin-resistant Staphylococcus aureus (MRSA) mediastinitis in a rat model

Methicillin-resistant Staphylococcus aureus (MRSA) mediastinitis after median sternotomy is a major complication of cardiac surgery with significant morbidity and mortality rates. We evaluated the efficacy of ceftobiprole medocaril in a new rat model of mediastinitis and compared it to vancomycin. The model was induced in 92 rats. Infection was induced immediately after median sternotomy by the injection of MRSA (strain 3020, 1 × 10(7) cfu/rat) into the sternal bone. After 24 h, rats (groups of 6-8) were treated intraperitoneally for 5 days or 14 days by either: (i) saline (control, q8h), (ii) ceftobiprole medocaril (70 or 100 mg/kg, q8h), or (iii) vancomycin (50 mg/kg, q12h). Efficacy was determined by a reduction in bacterial cfu in the sternum and spleen tissues. Comparisons were performed using the Mann-Whitney test. A 5-day treatment course of ceftobiprole at both doses tested lead to a significant reduction in MRSA load in the sternum (p < 0.01) as compared to the control group and compared to 5-day vancomycin treatment, which lead to a non-significant reduction (p = 0.07). Longer treatment (14 days) with ceftobiprole lead to a complete clearance of MRSA from the sternum, similarly to vancomycin. Ceftobiprole also showed a significant effect on eliminating MRSA dissemination to the spleen compared to saline-treated rats. Ceftobiprole was effective in treating MRSA mediastinitis in the rat model. In the 5-day course, ceftobiprole showed a significant reduction in sternal MRSA counts and was superior to vancomycin. After 14 days, both ceftobiprole and vancomycin showed clearance of MRSA from the sternum in more than 50 % of rats and almost complete clearance in the remainder.

Combined Therapy of Teicoplanin and Caffeic Acid Phenethyl Ester (CAPE) in the Treatment of Experimental Mediastinitis in the Rat

Post-sternotomy mediastinitis affects 1-3% of patients undergoing cardiac surgery and is lethal in 10-47% of these patients. We investigated the effect of an antioxidant/anti-inflammatory agent, caffeic acid phenethyl ester (CAPE), in the attenuation of inflammatory response induced by methicillin-resistant Staphylococcus aureus (MRSA) infection in a rat experimental mediastinitis model. Rats, divided into six equal groups, received MRSA precolonized stainless steel wire pieces implanted into their mediastinal spaces. Control group and CAPE control group received saline and CAPE 10 micromol/kg.day(-1 )respectively, where Group A received a single dose of teicoplanin 24 mg/kg i.m. for the first day and then 12 mg/kg.day(-1) . Group B received teicoplanin as in Group A plus CAPE 10 micromol/kg. day(-1 )intra-peritoneally. Group C received teicoplanin 60 mg/kg i.m. for the first day and then 30 mg/kg.day(-1 )and Group D received teicoplanin as in Group C plus CAPE 10 micromol/kg.day(-1) . By the end of 14 days rats were sacrificed and serum malondialdehyde (MDA), myeloperoxidase (MPO), nitric oxide (NO), urea and creatinine levels were evaluated. Mediastinal organ tissues were collected for histopathological analysis. Infection rates in all the drug-treated groups were lower than the control groups ( P=0.002) but statistical significance was attained only between the groups A and D ( P=0.018). In connective tissues and the peribronchial area polymorphonuclear leukocytic (PNL) infiltration in the treatment groups, although becoming very close, did not reach statistical significance (P =0.053, P=0.075, respectively). PNL infiltration especially in the peribronchial tissues of the Group B animals was found to be significantly less than the Control and CAPE Control groups with P values of 0.013 and 0.010, respectively. MDA and MPO levels were significantly lower in the treatment groups ( P<0.001 and P<0.001 respectively). Levels of the degradation products of NO were lower in treatment groups compared to two control groups (P=0.003, P= 0.005). NO levels in Group D were lowest among all treatment groups ( P=0.001). It has been demonstrated that although bacterial colonization can be controlled in mediastinitis, the inflammatory response persists. The combination of an antioxidant / anti-inflammatory agent, CAPE, added to standard antibiotic therapy might be effective in the treatment of post-sternotomy mediastinitis due to MRSA.

Decreasing methicillin-resistant Staphylococcus aureus surgical site infections with chlorhexidine and mupirocin

BACKGROUND

Surgical site infections (SSIs) associated with methicillin-resistant Staphylococcus aureus (MRSA) are a major complication of surgery. This study is part of a large infection control quality improvement effort to eliminate MRSA SSIs.

METHODS

This is an Institutional Review Board-approved, case-control study examining MRSA SSI rates before and after implementation of a facility-wide MRSA SSI prevention protocol in 2007. The protocol involved a 5-day course of intranasal mupirocin and nonrinse 2% chlorhexidine gluconate cloths.

RESULTS

In 2006, a total of 39 MRSA SSIs occurred after 9,976 procedures in patients who underwent orthopedic, vascular, cardiac, or neurosurgical procedures (rate = 0.39 per 100 procedures). The highest incidence occurred after cardiac surgery (rate = 1.24/100 procedures), and the lowest occurred after orthopedic surgery (rate = 0.28/100 procedures). In 2007, the MRSA SSI rate decreased to 20 of 9,818 procedures (rate = 0.20/100 procedures) in the 4 categories (P = .016; odds ratio, 1.92). In 2008, the MRSA SSI rate dropped again to 13 of 10,068 procedures (rate = 0.13/100 procedures) in the 4 categories (P = .0003; odds ratio, 3.04).

CONCLUSION

A 5-day course of intranasal mupirocin and nonrinse 2% chlorhexidine gluconate cloths may be beneficial in preventing MRSA SSIs in the non-general surgery population.

Vaccine review: "Staphyloccocus aureus vaccines: problems and prospects"

Staphylococcus aureus is a leading cause of both healthcare- and community-associated infections globally. S. aureus exhibits diverse clinical presentations, ranging from benign carriage and superficial skin and soft tissue infections to deep wound and organ/space infections, biofilm-related prosthesis infections, life-threatening bacteremia and sepsis. This broad clinical spectrum, together with the high incidence of these disease manifestations and magnitude of the diverse populations at risk, presents a high unmet medical need and a substantial burden to the healthcare system. With the increasing propensity of S. aureus to develop resistance to essentially all classes of antibiotics, alternative strategies, such as prophylactic vaccination to prevent S. aureus infections, are actively being pursued in healthcare settings. Within the last decade, the S. aureus vaccine field has witnessed two major vaccine failures in phase 3 clinical trials designed to prevent S. aureus infections in either patients undergoing cardiothoracic surgery or patients with end-stage renal disease undergoing hemodialysis. This review summarizes the potential underlying reasons why these two approaches may have failed, and proposes avenues that may provide successful vaccine approaches to prevent S. aureus disease in the future.

Methicillin-resistant Staphylococcus aureus (MRSA)

Staphylococcus aureus is one of the leading causes of surgical site infection (SSI). Over the past decade there has been an increase in methicillin-resistant S. aureus (MRSA). This is a subpopulation of the bacterium with unique resistance and virulence characteristics. Nasal colonisation with either S. aureus or MRSA has been demonstrated to be an important independent risk factor associated with the increasing incidence and severity of SSI after orthopaedic surgery. Furthermore, there is an economic burden related to SSI following orthopaedic surgery, with MRSA-associated SSI leading to longer hospital stays and increased hospital costs. Although there is some controversy about the effectiveness of screening and eradication programmes, the literature suggests that patients should be screened and MRSA-positive patients treated before surgical admission in order to reduce the risk of SSI.

Cite this article: Bone Joint J 2013;95-B:4–9.

Obesity and the risk and outcome of infection

The interactions between obesity and infectious diseases have recently received increasing recognition as emerging data have indicated an association between obesity and poor outcome in pandemic H1N1 influenza infection. Obesity is an established risk factor for surgical-site infections, nosocomial infections, periodontitis and skin infections. Several studies indicate that acute pancreatitis is more severe in the obese. Data are controversial and limited as regards the association between obesity and the risk and outcome of community-acquired infections such as pneumonia, bacteremia and sepsis and obesity and the course of HIV infection. As the cause-effect relationship between obesity and infection remains obscure in many infectious diseases, further studies are warranted. The consequences of obesity may have substantial effects on the global burden of infectious diseases.

Periprosthetic joint infection: the economic impact of methicillin-resistant infections

The orthopedic community has begun to witness a worrisome rise in the incidence of periprosthetic joint infections (PJIs) caused by resistant organisms. Besides other challenges associated with treating these infections, it appears that these infections may pose a higher cost compared to infections caused by sensitive organisms. Significantly higher cost of care for treatment of infections due to methicillin-resistant organisms were seen at a mean of $107,264 per case compared to $68,053 for treating PJI caused by sensitive strains (P < .0001). More effective strategies for preventing the spread of infections caused by resistant organisms need to be implemented to ease the social and economic strains facing the orthopedic community due to resistant organisms.

Mitral valve replacement via right thoracotomy approach for prevention of mediastinitis in a female patient with long-term uncontrolled diabetes mellitus: a case report

A 76-year-old woman with a history of percutaneous transvenous mitral commissurotomy and repeated hospital admissions due to heart failure was referred for an operation for severe mitral valve stenosis. She presented with hypertension, hyperlipidemia and cerebral infarction with stenosis of right internal carotid artery, retinopathy, neuropathy and nephropathy caused by long-term uncontrolled diabetes mellitus, hemoglobin A1c of 9.4%, and New York Heart Association (NYHA) functional classification of 3/4. Echocardiography revealed severe mitral valve stenosis with mitral valve area of 0.6 cm², moderate tricuspid valve regurgitation, and dilatation of the left atrium. Taking into consideration the NYHA functional classification and severe mitral valve stenosis, an immediate surgical intervention designed to prevent mediastinitis was performed. The approach was via the right 4th thoracotomy, as conventional sternotomy would raise the risk of mediastinitis. Postoperative antibiotics were administered intravenously for 2 days, and signs of infection were not recognized.

In patients with long-term uncontrolled diabetes mellitus, mid-line sternotomy can easily cause mediastinitis. The choice of operative approach plays an important role in preventing this complication. In this report, the importance of the conventional right thoracotomy for prevention for mediastinitis is reviewed.

Risk factors for methicillin-resistant Staphylococcus aureus (MRSA) infection in dogs and cats: a case-control study

Risk factors for methicillin-resistant Staphylococcus aureus (MRSA) infection in dogs and cats were investigated in an unmatched case-control study. A total of 197 animals from 150 veterinary practices across the United Kingdom was enrolled, including 105 MRSA cases and 92 controls with methicillin-susceptible S. aureus (MSSA) infection. The association of owners and veterinarian staff with the human healthcare sector (HCS) and animal-related characteristics such as signalment, antimicrobial and immunosuppressive therapy, and surgery were evaluated as putative risk factors using logistic regression. We found that significant risk factors for MRSA infection were the number of antimicrobial courses (p=0.005), number of days admitted to veterinary clinics (p=0.003) and having received surgical implants (p=0.001). In addition, the odds of contact with humans which had been ill and admitted to hospital (p=0.062) were higher in MRSA infected pets than in MSSA controls. The risk factors identified in this study highlight the need to increase vigilance towards identification of companion animal groups at risk and to advocate responsible and judicious use of antimicrobials in small animal practice.

Treatments for skin and soft-tissue and surgical site infections due to MDR Gram-positive bacteria

Gram-positive aerobes are the most common organisms in hospitalized patients with skin and soft-tissue infections (SSTIs). Staphylococcus aureus is the most common Gram-positive aerobe among these infections with methicillin-resistant S. aureus (MRSA) the most common pathogen. The increased prevalence of MRSA has been noted in the hospital as well in the community setting. In choosing antimicrobial therapy, assessment of the infection and patient characteristics, such as animal exposure, travel history, underlying diseases, recent trauma, bites, burns, and water exposure, must be considered. Community-acquired MRSA strains are showing resistance to more antimicrobial classes, and b-lactam antibiotics can no longer be considered first-line therapy for community-acquired SSTIs. For more serious infections, there are several new antimicrobial options with good MRSA coverage, including linezolid, daptomycin, and tigecycline. Several agents are currently under clinical investigation or are being considered for approval by the US Food and Drug Administration, including ceftobiprole, dalbavancin, iclaprim, oritavancin, and telavancin.

Update: Methicillin-resistant Staphylococcus aureus screening and decolonization in cardiac surgery

Methicillin-resistant Staphylococcus aureus (MRSA) has become a concerning multidrug-resistant organism, expanding further outside the hospital setting. Cardiothoracic surgery patients are at an increased risk for mediastinitis and other surgical site infections, which may be further complicated by MRSA. To reduce MRSA surgical site infections, multidisciplinary active surveillance should be implemented in at least high-risk patients, incorporating basic infection control practices, appropriate antibiotic prophylaxis, and decolonization. This article will review the various guidelines, addressing the role of MRSA active surveillance in cardiothoracic surgery, and provide guidance for cardiothoracic surgeons.

Incidence of and preoperative risk factors for Staphylococcus aureus bacteremia and chest wound infection after cardiac surgery

OBJECTIVE

Staphylococcus aureus infections after cardiac surgery result in significant morbidity and mortality. Identifying patients at elevated risk for these infections preoperatively could facilitate efforts to reduce infection rates. The objectives of this study were to estimate the incidence of postoperative S. aureus infections in cardiac surgery patients, to identify preoperative risk factors for these infections, and to establish a patient risk profile by means of data available to clinicians prior to surgery.

DESIGN

Cohort study.

SETTING

Eight medical centers that participate in the Society of Thoracic Surgeons National Cardiac Database.

PATIENTS

Patients who were undergoing elective cardiac surgery during the period January 1, 2000 through December 31, 2004.

METHODS

Clinical and microbiological data from 16,386 patients were combined. Multivariable stepwise logistic regression analysis was performed to predict S. aureus infection, which was defined by culture results.

RESULTS

Of the 16,386 patients, 205 (1.3%) developed S. aureus bloodstream or chest wound infection within 90 days after surgery. On multivariable analysis, bootstrap-validated preoperative risk factors for S. aureus bloodstream or chest wound infection included a body mass index greater than 40 (adjusted odds ratio [aOR], 1.9 [95% confidence interval {CI}, 1.1-3.2]), chronic renal failure (aOR, 1.8 [95% CI, 1.1-2.9]), and chronic lung disease (aOR, 1.4 [95% CI, 1.0-2.0]). Only 8 patients had all 3 risk factors.

CONCLUSIONS

Although preoperative risk factors can be easily identified, the majority of patients who developed S. aureus infections after cardiac surgery did not have any risk factors. Preventive measures should not be restricted to a select group of cardiac surgery patients and should rather address the entire patient population.

Staphylococcal surgical site infections

Staphylococcus aureus is the leading cause of surgical site infections (SSI) in the United States. In particular, SSI caused by methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a devastating complication, leading to increased mortality rates, increased length of hospitalization, and increased costs. Proven strategies for prevention of SSI caused by S aureus include addressing modifiable risk factors and correct choice and timing of antimicrobial prophylaxis. Other strategies, including decolonization and the use of vancomycin, remain controversial.

Strategies to prevent surgical site infections in acute care hospitals

Previously published guidelines are available that provide comprehensive recommendations for detecting and preventing healthcare-associated infections. The intent of this document is to highlight practical recommendations in a concise format designed to assist acute care hospitals to implement and prioritize their surgical site infection (SSI) prevention efforts. Refer to the Society for Healthcare Epidemiology of America/Infectious Diseases Society of America “Compendium of Strategies to Prevent Healthcare-Associated Infections” Executive Summary and Introduction and accompanying editorial for additional discussion.

1. Burden of SSIs as complications in acute care facilities.

a. SSIs occur in 2%-5% of patients undergoing inpatient surgery in the United States.

b. Approximately 500,000 SSIs occur each year.

2. Outcomes associated with SSI

a. Each SSI is associated with approximately 7-10 additional postoperative hospital days.

b. Patients with an SSI have a 2-11 times higher risk of death, compared with operative patients without an SSI.

i. Seventy-seven percent of deaths among patients with SSI are direcdy attributable to SSI.

c. Attributable costs of SSI vary, depending on the type of operative procedure and the type of infecting pathogen; published estimates range from $3,000 to $29,000.

i. SSIs are believed to account for up to $10 billion annually in healthcare expenditures.

1. Definitions

a. The Centers for Disease Control and Prevention National Nosocomial Infections Surveillance System and the National Healthcare Safety Network definitions for SSI are widely used.

b. SSIs are classified as follows (Figure):

i. Superficial incisional (involving only skin or subcutaneous tissue of the incision)

ii. Deep incisional (involving fascia and/or muscular layers)

iii. Organ/space

Poor functional status as a risk factor for surgical site infection due to methicillin-resistant Staphylococcus aureus

OBJECTIVE

To identify risk factors for surgical site infection (SSI) due to methicillin-resistant Staphylococcus aureus (MRSA).

DESIGN

Prospective case-control study.

SETTING

One tertiary and 6 community-based institutions in the southeastern United States.

METHODS

We compared patients with SSI due to MRSA with 2 control groups: matched uninfected surgical patients and patients with SSI due to methicillin-susceptible S. aureus (MSSA). Multivariable logistic regression was used to determine variables independently associated with SSI due to MRSA, compared with each control group.

RESULTS

During the 5-year study period, 150 case patients with SSI due to MRSA were identified and compared with 231 matched uninfected control patients and 128 control patients with SSI due to MSSA. Two variables were independently associated with SSI due to MRSA in both multivariable regression models: need for assistance with 3 or more activities of daily living (odds ratio [OR] compared with uninfected patients, 3.97 [95% confidence interval {CI}, 2.18-7.25]; OR compared with patients with SSI due to MSSA, 3.88 [95% CI, 1.91-7.87]) and prolonged duration of surgery (OR compared with uninfected patients, 1.98 [95% CI, 1.11-3.55]; OR compared with patients with SSI due to MSSA, 2.33 [95% CI, 1.17-4.62]). Lack of independence (ie, poor functional status) remained associated with an increased risk of SSI due to MRSA after stratifying by age.

CONCLUSIONS

Poor functional status was highly associated with SSI due to MRSA in adult surgical patients, regardless of age. A patient's level of independence can be easily determined, and this information can be used preoperatively to target preventive interventions.

Staphylococcus aureus mediastinitis and sternal osteomyelitis following median sternotomy in a rat model

OBJECTIVES

Median sternotomy (MS) wound infections are severe complications causing high morbidity and mortality after cardiac surgery. We aimed to develop a new Staphylococcus aureus mediastinitis and sternal osteomyelitis model in rats that can be used to evaluate the efficacy of new antimicrobial treatments.

METHODS AND RESULTS

A complete MS wound was induced in anaesthetized rats. S. aureus was injected into the sternum. Kinetics of bacterial growth in the sternum (10(7) cfu/sternum) was assessed for histopathology and bacterial counts. A non-infected MS group served as a control. To evaluate antibiotic efficacy, 5 days of intraperitoneal vancomycin therapy (50 mg/kg, twice a day) was initiated 24 h following bacterial challenge. Macroscopic and histological examination confirmed that infection resulted in sternitis and mediastinitis. S. aureus bacterial counts in the sternum were inoculum-dependent, and it was proven that infecting rats with an inoculum of 10(7) cfu/sternum induced mediastinitis and sternal osteomyelitis. At this inoculum, bacterial counts in the infected sternum increased with time, reaching a maximum level of 2 +/- 1 x 10(7) cfu/g of sternum 8-12 days post-infection and then decreased with time to 2 x 10(4) cfu/g of sternum 20 days after infection. Histological changes paralleled bacterial counts. Vancomycin administration showed a protective effect against induction of sternal osteomyelitis; sternums from vancomycin-treated rats showed a significant decrease in S. aureus counts by 0.72 +/- 0.35 log cfu/g compared with untreated controls (P = 0.0162).

CONCLUSIONS

This new rat model of S. aureus sternal osteomyelitis and mediastinitis allows quantitative measurement of bacterial counts in the sternum. This model is reproducible and simple and thus suitable for the evaluation of new antimicrobials and new treatment modalities in MS infections.

Matching criteria in case-control studies in the field of antimicrobial resistance

OBJECTIVE

We evaluated the available evidence from case-control studies in the field of antimicrobial resistance to identify the degree that matching was performed and the criteria used to do so.

METHODS

We performed a systematic search of the PubMed database (articles archived by 08/2006) to identify relevant studies. Studies that used the individual matching technique were further analyzed.

RESULTS

115 case-control studies with a focus on antimicrobial resistance were identified: 28 regarding Acinetobacter baumannii, 25 regarding Pseudomonas aeruginosa, and 62 for other bacteria. Individual matching was performed in 32 (27.8%) out of the 115 studies. Age was the most frequently used matching criterion in 22 of 32 (69%) evaluated matched case-control studies, while sex was used in 11 (34%), presence of underlying illness in 8 (25%), site of infection in 5 (16%), and area of residence in 4 studies (12.5%). Other criteria were used in less than 10% of the studies. Analysis of data for matched pairs was performed in 18 of 32 (56.3%) studies that used a matched case-control design.

DISCUSSION

The available evidence from the analyzed data from case-control studies in the field of antimicrobial resistance shows that individual matching is employed only in a proportion of such studies and only for a few characteristics, when it was used. Also, analysis for matched pairs was not used by almost a half of the relevant studies.

Staphylococcus aureus poststernotomy mediastinitis: description of two distinct acquisition pathways with different potential preventive approaches

OBJECTIVE

Determining the acquisition routes of infection is crucial to designing specific preventive approaches against Staphylococcus aureus poststernotomy mediastinitis.

METHODS

From 2002 to 2004, a nasal sample was obtained from patients before cardiac surgery. We collected clinical and microbiologic data of all episodes of S aureus poststernotomy mediastinitis. A case-control study (3:1) was performed to confirm the role of previous preoperative nasal colonization by S aureus as a risk factor for S aureus poststernotomy mediastinitis. Pulsed field gel electrophoresis molecular analysis of nasal and surgical site S aureus isolates was performed to analyze their relatedness in each patient with poststernotomy mediastinitis and with other patients of the study cohort.

RESULTS

S aureus nasal cultures were positive in 228 (15.9%) of 1432 patients: methicillin-susceptible S aureus in 222 (15.5%) and meticillin-resistant S aureus in 6 (0.4%). S aureus poststernotomy mediastinitis was diagnosed in 17 (1.2%) of 1432 patients: 9 (3.95%) of 228 in colonized patients versus 8 (0.66%) of 1204 in noncolonized patients (P < .0001). Seven of 9 patients (1.2%) with methicillin-susceptible S aureus had an identical isolate by pulsed field gel electrophoresis in preoperative nasal and surgical-site cultures, but no clonal relatedness was shown among the isolates from these 9 patients. None of the 8 patients with methicillin-resistant S aureus poststernotomy mediastinitis had an identical isolate by pulsed field gel electrophoresis in preoperative nasal and surgical-site cultures, and the same clone of methicillin-resistant S aureus was responsible for all these cases.

CONCLUSIONS

Endogenous [corrected] nasal colonization often precedes methicillin-resistant S aureus poststernotomy mediastinitis, which suggests that preoperative [corrected] decontamination is adequate for preventing methicillin-susceptible [corrected] S aureus poststernotomy mediastinitis, whereas hospital infection control measures seem to be the major factor for preventing methicillin-resistant S aureus poststernotomy mediastinitis.

Comparison of routine prophylaxis with vancomycin or cefazolin for femoral neck fracture surgery: microbiological and clinical outcomes

OBJECTIVE

To assess the impact of antibiotic prophylaxis on the emergence of vancomycin-resistant strains of Enterococcus faecium, Enterococcus faecalis, and Staphylococcus aureus and the incidence of surgical site infection (SSI) after vancomycin or cefazolin prophylaxis for femoral neck fracture surgery.

DESIGN

Prospective cohort study.

SETTING

A hospital with a high prevalence of methicillin-resistant S. aureus (MRSA) carriage.

PATIENTS

All patients admitted with a femoral neck fracture from March 1, 2004 through February 28, 2005 were prospectively identified and screened for MRSA and vancomycin-resistant (VRE) carriage at admission and at day 7. Deep incisional and organ/space SSIs were also recorded.

RESULTS

Of 263 patients included in the study, 152 (58%) received cefazolin and 106 (40%) received vancomycin. At admission, the prevalence of MRSA carriage was 6.8%; it was 12% among patients with risk factors and 2.2% among patients with no risk factors (P=.002). At day 7 after surgery, there were 6 patients (2%) who had hospital-acquired MRSA, corresponding to 0.7% in the cefazolin group and 5% in the vancomycin group (P=.04); none of the MRSA isolates were resistant to glycopeptides. The rate of VRE carriage at admission was 0.4%. Three patients (1%) had acquired carriage of VRE (1 had E. faecium and 2 had E. faecalis); all 3 were in the cefazolin group (2% of patients) and none in the vancomycin group (P=.27). Eight SSIs (3%) occurred, 4% in the cefazolin group and 2% in the vancomycin group (P=.47).

CONCLUSIONS

This preliminary study demonstrates that cefazolin and vancomycin prophylaxis have similar impacts on the emergence of glycopeptide-resistant pathogens. Neither MRSA infection nor increased rates of SSI with other bacteria were observed in the vancomycin group, suggesting that a larger multicenter study should be initiated.

Risk factors for 1-year mortality after postoperative mediastinitis

OBJECTIVE

Postoperative mediastinitis after median sternotomy is associated with disability and mortality. The aim of this study was to identify risk factors for mortality 1 year after postoperative mediastinitis diagnosis.

METHODS

Postoperative mediastinitis was defined as an organ-space infection involving the mediastinum and necessitating debridement. A total of 183 cases of postoperative mediastinitis were prospectively identified from infection control databases. By using univariate and multivariate analysis, clinical risk factors for 1-year mortality were identified.

RESULTS

Of 183 patients, 36 (19.7%) died within 3 months of the initial operation. Overall, 51 (33%) died during the study period (the median time to death from the date of diagnosis was 37 days [interquartile range, 11,139 days]). In multivariate analysis, independent predictors of 1-year mortality were a greater than 3-day delay in sternal closure after debridement (hazard ratio, 6.27; P < .001), age greater than 65 years (hazard ratio, 2.29; P = .015), serum creatinine level greater than 2 mg/dL before debridement (hazard ratio, 2.52; P = .019), stay in an intensive care unit before sternal debridement (hazard ratio, 5.56; P < .001), and postoperative mediastinitis due to methicillin-resistant Staphylococcus aureus (hazard ratio, 2.13; P = .02). Treatment with antibiotics with in vitro activity against the infecting pathogen within 7 days of initial debridement was associated with a decreased risk for mortality (hazard ratio, 0.40; P = .03).

CONCLUSIONS

Our data suggest that, to improve long-term survival, patients with postoperative mediastinitis should undergo sternal closure within 72 hours after sternal debridement and should receive effective antimicrobial therapy based on operative culture results.

Personal hygiene and methicillin-resistant Staphylococcus aureus infection

Methicillin-resistant Staphylococcus aureus (MRSA) infections outside the healthcare setting are an increasing concern. We conducted a case-control study to investigate an MRSA outbreak during 2002-2003 in a Missouri prison and focused on hygiene factors. Information on sociodemographic characteristics, medical history, and hygiene practices of study participants was collected by interview and medical record review. Logistic regression was used to evaluate MRSA infection in relation to hygiene factors individually and as a composite hygiene score; potential confounding factors were controlled. Selected MRSA isolates were analyzed by pulsed-field gel electrophoresis (PFGE). MRSA infection was significantly associated with a low composite hygiene score. Transmission among prison inmates appeared to be responsible for this outbreak. PFGE analysis showed that isolates were indistinguishable and associated with community-onset MRSA infections in other US prisons. Improving hygiene practices and environmental conditions may help prevent and interrupt future MRSA outbreaks in prison settings.

Personal hygiene and methicillin-resistant Staphylococcus aureus infection

Improving personal hygienic practices may prevent and control MRSA outbreaks.

Methicillin-resistant Staphylococcus aureus (MRSA) infections outside the healthcare setting are an increasing concern. We conducted a case-control study to investigate an MRSA outbreak during 2002–2003 in a Missouri prison and focused on hygiene factors. Information on sociodemographic characteristics, medical history, and hygiene practices of study participants was collected by interview and medical record review. Logistic regression was used to evaluate MRSA infection in relation to hygiene factors individually and as a composite hygiene score; potential confounding factors were controlled. Selected MRSA isolates were analyzed by pulsed-field gel electrophoresis (PFGE). MRSA infection was significantly associated with a low composite hygiene score. Transmission among prison inmates appeared to be responsible for this outbreak. PFGE analysis showed that isolates were indistinguishable and associated with community-onset MRSA infections in other US prisons. Improving hygiene practices and environmental conditions may help prevent and interrupt future MRSA outbreaks in prison settings.

Clinical predictors of major infections after cardiac surgery

BACKGROUND

Major infections are infrequent but important complications of cardiac surgery. Predicting their occurrence is essential for future prevention. The objective of the current investigation was to create and validate a bedside scoring system to estimate patient risk for major infection (mediastinitis, thoracotomy or vein harvest site infection, or septicemia) after coronary artery bypass grafting.

METHODS AND RESULTS

Using the Society of Thoracic Surgeons National Cardiac Database, we analyzed 331 429 coronary artery bypass grafting cases from January 1, 2002, to December 31, 2003, to identify risk factors for major infection. Using logistic regression, 2 models were generated and validated using split-sample validation: (1) One limited to preoperative characteristics (preop model) and (2) one model including both preoperative and intraoperative characteristics (combined model). Major infection occurred in 11 636 patients (3.51%) (25.1% mediastinitis, 32.6% saphenous harvest site, 35.0% septicemia, 0.5% thoracotomy, 6.8% multiple sites). Patients with major infection had significantly higher mortality (17.3% versus 3.0%, P<0.0001) and postoperative length of stay >14 days (47.0% versus 5.9%, P<0.0001) than patients without major infection. Both the preop model (c-index 0.697) and combined model (c-index: 0.708) successfully discriminated between high- and low-risk patients. A simplified risk scoring system of 12 variables accurately predicted risk for major infection.

CONCLUSIONS

We identified and validated a model that can identify patients undergoing cardiac surgery who are at high risk for major infection. These high-risk patients may be targeted for perioperative intervention strategies to reduce rates of major infection.