Increase in the rate of sternal surgical site infection after coronary artery bypass graft: a marker of higher severity of illness

Mediastinitis in open heart surgery: a systematic review and meta-analysis of risk factors

Objective. We aimed to summarize the evidence from observational studies examining the risk factors of the incidence of mediastinitis in open heart surgery. Design. The study was a systematic review and meta-analysis of cohorts and case-control studies. Material and methods. We searched the literature and 74 studies with at least one risk factor were identified. Both fixed and random effects models were used. Heterogeneity between studies was examined by subgroup and meta-regression analysis. Publication bias or small study effects were evaluated and corrected by limit meta-analysis. Results. When correcting for small study effect, presence of obesity as estimated from 43 studies had Odds Ratio OR = 2.26. (95% CI: 2.17-2.36). This risk was increasing with decreasing latitude of study place. Presence of diabetes mellitus from 63 studies carried an OR = 1.90 (95% CI: 1.59-2.27). Presence of Chronic Obstructive Pulmonary Disease (COPD) from 30 studies had an OR = 2.59 (95% CI: 2.22-2.85). Presence of bilateral intramammary graft (BIMA) from 23 studies carried an OR = 2.54 (95% CI: 2.07-3.13). This risk was increasing with increasing frequency of female patients in the study population. Conclusion. Evidence from this study showed the robustness of the risk factors in the pathogenesis of mediastinitis. Preventive measures can be implemented for reducing obesity, especially in lower latitude countries. Furthermore, it is mandatory to monitor perioperative hyperglycemias with continuous insulin infusion. Use of skeletonized BIMA carries higher risk of mediastinitis especially in female patients without evidence of beneficial effect on survival for the time being.

Coronary artery bypass surgery in Syrian refugees. Outcomes in a Turkish tertiary center

OBJECTIVE

To assess  outcomes of Syrian refugees undergoing coronary artery bypass surgery in a tertiary hospital in Turkey.

METHODS

 We sought for in-hospital mortality and one year all-cause mortality as the main outcomes. We reviewed records of 67 Syrian and 427 Turkish patients undergoing isolated coronary bypass surgery between 2015 January and 2017 January retrospectively.  Results: History of coronary, peripheral and carotid artery diseases and obesity were more frequent in Syrian patients. C-reactive protein levels were  higher in Syrian patients whereas lipid profiles and systolic functions of the 2 groups were similar. Syrian patients more frequently presented with the acute coronary syndrome (26.9% versus 15.5%, p<0.001).  SYNTAX I (Synergy between PCI with Taxus and Cardiac Surgery) and SYNTAX II-PCI were higher in Syrian patients whereas SYNTAX II-CABG  was similar with Turkish patients. Extubation time was longer and amount of the hemorrhage was greater in Syrian patients; however, bleeding revision was not increased. Although wound infection was more frequent in Syrian patients, postoperative complications were similar between groups. In-hospital mortality and one year all-cause mortality did not differ between Syrian (n=1; 1.5% versus n=13; 13.1%) (p=0.476) and Turkish patients (n=3; 4.5% versus n=25; 5.9%) (p=0.63).

CONCLUSION

Syrian patients had higher SYNTAX I and SYNTAX II PCI scores, but not SYNTAX II CABG score compared with Turkish patients. Intraoperative and postoperative complications were similar. In-hospital mortality and one year all-cause mortality of Syrian patients were similar with Turkish patients. Surgical outcomes of Syrian patients were acceptable. Primary prevention of obesity must be provided. Aggressive secondary preventive measures must be taken due to increased severity of coronary artery disease.

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.

Latitude of the study place and age of the patient are associated with incidence of mediastinitis and microbiology in open-heart surgery: a systematic review and meta-analysis

Objective

We aimed to summarize the pooled frequency of mediastinitis following open-heart surgery caused by Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), and Gram-negative bacteria.

Design

This study was a systematic review and a meta-analysis of prospective and retrospective cohort studies.

Materials and methods

We searched the literature, and a total of 97 cohort studies were identified. Random-effect model was used to synthesize the results. Heterogeneity between studies was examined by subgroup and meta-regression analyses, considering study and patient-level variables. Small-study effect was evaluated.

Results

Substantial heterogeneity was present. The estimated incidence of mediastinitis evaluated from 97 studies was 1.58% (95% confidence intervals [CI] 1.42, 1.75) and that of Gram-positive bacteria, Gram-negative bacteria, and MRSA bacteria evaluated from 63 studies was 0.90% (95% CI 0.81, 1.21), 0.24% (95% CI 0.18, 0.32), and 0.08% (95% CI 0.05, 0.12), respectively. A meta-regression pinpointed negative association between the frequency of mediastinitis and latitude of study place and positive association between the frequency of mediastinitis and the age of the patient at operation. Multivariate meta-regression showed that prospective cohort design and age of the patients and latitude of study place together or in combination accounted for 17% of heterogeneity for end point frequency of mediastinitis, 16.3% for Gram-positive bacteria, 14.7% for Gram-negative bacteria, and 23.3% for MRSA bacteria.

Conclusion

Evidence from this study suggests the importance of latitude of study place and advanced age as risk factors of mediastinitis. Latitude is a marker of thermally regulated bacterial virulence and other local surgical practice. There is concern of increasing risk of mediastinitis and of MRSA in elderly patients undergoing sternotomy.

Diabetes and Risk of Surgical Site Infection: A Systematic Review and Meta-analysis

OBJECTIVE To determine the independent association between diabetes and surgical site infection (SSI) across multiple surgical procedures. DESIGN Systematic review and meta-analysis. METHODS Studies indexed in PubMed published between December 1985 and through July 2015 were identified through the search terms "risk factors" or "glucose" and "surgical site infection." A total of 3,631 abstracts were identified through the initial search terms. Full texts were reviewed for 522 articles. Of these, 94 articles met the criteria for inclusion. Standardized data collection forms were used to extract study-specific estimates for diabetes, blood glucose levels, and body mass index (BMI). A random-effects meta-analysis was used to generate pooled estimates, and meta-regression was used to evaluate specific hypothesized sources of heterogeneity. RESULTS The primary outcome was SSI, as defined by the Centers for Disease Control and Prevention surveillance criteria. The overall effect size for the association between diabetes and SSI was odds ratio (OR)=1.53 (95% predictive interval [PI], 1.11-2.12; I2, 57.2%). SSI class, study design, or patient BMI did not significantly impact study results in a meta-regression model. The association was higher for cardiac surgery 2.03 (95% PI, 1.13-4.05) compared with surgeries of other types (P=.001). CONCLUSIONS These results support the consideration of diabetes as an independent risk factor for SSIs for multiple surgical procedure types. Continued efforts are needed to improve surgical outcomes for diabetic patients. Infect. Control Hosp. Epidemiol. 2015;37(1):88-99.

Impact of diabetes on mortality and complications after coronary artery by-pass graft operation in patients with left main coronary artery disease

PURPOSE

Left main disease (LMD) is a severe form of coronary artery disease (CAD). Fifty percent of patients with LMD treated conservatively die within 3-5 years of diagnosis. The aim of the study was to assess the influence of type 2 diabetes on early and late (2-year) prognosis and the risk of complications after coronary artery by-pass graft (CABG) surgery in patients with LMD.

MATERIAL/METHODS

We enrolled 257 patients diagnosed with LMD. 169 (67%) underwent CABG, 19 (8%) percutaneous coronary intervention (PCI) without left main stem protection. 30 (12%) patients had CABG previously. Patients treated with CABG were divided into two groups - with and without diabetes. There were 43 (25.4%) patients with diabetes and 126 (74.6%) without diabetes.

RESULTS

We observed more complications with wound healing (40.5% vs. 12.8%, p<0.001) and sternal dehiscence (23.8% vs. 4.0%, p<0.001) after CABG in patients with diabetes. There were no differences in 7-day, 30-day, 3-month and 1-year mortality. 2-Year mortality was also similar in both groups (11.6% vs. 11.1%, p=0.928). Patients with diabetes were more frequently hospitalized due to other reasons than angina (39.5% vs. 20.6%, p=0.014).

CONCLUSIONS

Patients with diabetes and LMD had more often complications with wound healing and sternal dehiscence after CABG than patients without diabetes. Type 2 diabetes did not influence early and late mortality in patients with LMD treated with cardiac surgery, but the presence of diabetes was associated with more frequent hospitalizations.

High-dose continuous oxacillin infusion results in achievement of pharmacokinetics targets in critically ill patients with deep sternal wound infections following cardiac surgery

Knowledge regarding antimicrobial therapy strategies in deep sternal wound infections (DSWI) following cardiac surgery is limited. Therefore, we aimed to determine the steady-state plasma and mediastinal concentrations of oxacillin administered by continuous infusion in critically ill patients with DSWI and to compare these concentrations with the susceptibility of staphylococci recovered. A continuous infusion of oxacillin (150 to 200 mg/kg of body weight/24 h) was administered after a loading dose (50 mg/kg). Plasma and mediastinal concentrations of total and unbound oxacillin were determined 4 h after the loading dose (H4) and then at day 1 (H24) and day 2 (H48). Twelve patients were included. Nine patients exhibited bacteremia, 5 were in septic shock, 8 were positive for Staphylococcus aureus, and 4 were positive for coagulase-negative staphylococci. The median MIC (first to third interquartile range) was 0.25 (0.24 to 0.41) mg/liter. Median plasma concentrations of total and unbound oxacillin at H4, H24, and H48 were, respectively, 64.4 (41.4 to 78.5) and 20.4 (12.4 to 30.4) mg/liter, 56.9 (31.4 to 80.6) and 21.7 (6.5 to 27.3) mg/liter, and 57.5 (32.2 to 85.1) and 20 (14.3 to 35.7) mg/liter. The median mediastinal concentrations of total and unbound oxacillin at H4, H24, and H48 were, respectively, 2.3 (0.7 to 25.9) and 0.9 (<0.5 to 15) mg/liter, 29.1 (19.7 to 38.2) and 12.6 (5.9 to 19.8) mg/liter, and 31.6 (14.9 to 42.9) and 17.1 (6.7 to 26.7) mg/liter. High-dose oxacillin delivered by continuous infusion is a valuable strategy to achieve our pharmacokinetic target (4× MIC) at the site of action at H24. But concerns remain in cases of higher MICs, emphasizing the need for clinicians to obtain the MICs for the bacteria and to monitor oxacillin concentrations, especially the unbound forms, at the target site.

Surgical site infections following coronary artery bypass graft procedures: 10 years of surveillance data

BACKGROUND

Surgical site infections following coronary artery bypass graft (CABG) procedures pose substantial burden on patients and healthcare systems. This study aims to describe the incidence of surgical site infections and causative pathogens following CABG surgery over the period 2003-2012, and to identify risk factors for complex sternal site infections.

METHODS

Routine computerised surveillance data were collected from three public hospitals in Queensland, Australia in which CABG surgery was performed between 2003 and 2012. Surgical site infection rates were calculated by types of infection (superficial/complex) and incision sites (sternal/harvest sites). Patient and procedural characteristics were evaluated as risk factors for complex sternal site infections using a logistic regression model.

RESULTS

There were 1,702 surgical site infections (518 at sternal sites and 1,184 at harvest sites) following 14,546 CABG procedures performed. Among 732 pathogens isolated, Methicillin-sensitive Staphylococcus aureus accounted for 28.3% of the isolates, Pseudomonas aeruginosa 18.3%, methicillin-resistant Staphylococcus aureus 14.6%, and Enterobacter species 6.7%. Proportions of Gram-negative bacteria elevated from 37.8% in 2003 to 61.8% in 2009, followed by a reduction to 42.4% in 2012. Crude rates of complex sternal site infections increased over the reporting period, ranging from 0.7% in 2004 to 2.6% in 2011. Two factors associated with increased risk of complex sternal site infections were identified: patients with an ASA (American Society of Anaesthesiologists) score of 4 or 5 (reference score of 3, OR 1.83, 95% CI 1.36-2.47) and absence of documentation of antibiotic prophylaxis (OR 2.03, 95% CI 1.12-3.69).

CONCLUSIONS

Compared with previous studies, our data indicate the importance of Gram-negative organisms as causative agents for surgical site infections following CABG surgery. An increase in complex sternal site infection rates can be partially explained by the increasing proportion of patients with more severe underlying disease.

Impact of Medicare's payment policy on mediastinitis following coronary artery bypass graft surgery in US hospitals

BACKGROUND

The Centers for Medicare and Medicaid Services (CMS) implemented a policy in October 2008 to eliminate additional Medicare payment for mediastinitis following coronary artery bypass graft (CABG) surgery.

OBJECTIVE

To evaluate the impact of this policy on mediastinitis rates, using Medicare claims and National Healthcare Safety Network (NHSN) prospective surveillance data.

METHODS

We used an interrupted time series design to compare mediastinitis rates before and after the policy, adjusted for secular trends. Billing rates came from Medicare inpatient claims following 638,761 CABG procedures in 1,234 US hospitals (January 2006-September 2010). Prospective surveillance rates came from 151 NHSN hospitals in 29 states performing 94,739 CABG procedures (January 2007-September 2010). Logistic regression mixed-effects models estimated trends for mediastinitis rates.

RESULTS

We found a sudden drop in coding for index admission mediastinitis at the time of policy implementation (odds ratio, 0.36 [95% confidence interval (CI), 0.23-0.57]) and a decreasing trend in coding for index admission mediastinitis in the postintervention period compared with the preintervention period (ratio of slopes, 0.83 [95% CI, 0.74-0.95]). However, we saw no impact of the policy on infection rates as measured using NHSN data. Our results were not affected by changes in patient risk over time, heterogeneity in hospital demographics, or timing of hospital participation in NHSN.

CONCLUSIONS

The CMS policy of withholding additional Medicare payment for mediastinitis on the basis of claims-based evidence of infection was associated with changes in coding for infections but not with changes in actual infection rates during the first 2 years after policy implementation.

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.

An update review on risk factors and scales for prediction of deep sternal wound infections

Surgical site infections are the most common nosocomial infections in surgical patients. The preventable and the unmodifiable risk factors for deep sternal wound infections (DSWI) have been amply assessed in the literature. The aim of this review was to describe the results of the numerous published studies to describe all the DSWI risk factors and the scales devised to predict SWI, with a view to providing an update on this issue. A comprehensive search of the Medline and Embase databases was performed (considering studies from January 1995 to April 2011); and a manual search was also conducted using references cited in original publications and relevant review articles. There are several risk factors associated with DSWI, which could be classified in four categories as demographic (e.g. sex and age), behavioural (e.g. smoking and obesity), baseline clinical conditions (e.g. diabetes, hypertension and COPD) and surgical operative risk factors (e.g. duration of operation and emergency operation). Six scales for predicting the risk of DSWI are described in the literature: they vary not only in accuracy but also in ease of application and they are applied at different times (some only preoperatively and others also postoperatively). This study provides a broad update on our knowledge of the risk factors for DSWI and the scales for prediction with a view to improving the management of infections at cardiosurgery units.

Clinical features and outcomes in patients with diabetes mellitus undergoing coronary artery bypass graft in a reference center in southern Brazil

OBJECTIVE

To describe clinical/laboratory features of patients undergoing coronary artery bypass graft (CABG) in a cardiology reference center.

METHODS

Cohort study; data from patients undergoing CABG (January 2004 to February 2006, n = 717) were evaluated for clinical/laboratory features before, during and after surgery (infections, duration of hospital stay, deaths).

RESULTS

Patients were 61.9 ± 11 years old, 67.1% males, 29.6% diabetics. Intraoperatively, diabetics had a central venous catheter placed for a longer period (p < 0.001), but extracorporeal circulation, aortic clamping and total surgery times were similar to those for non-diabetics. Infection occurred in 19.1% of patients (40.1% diabetics vs. 10.3% non-diabetics, p < 0.001). The duration of hospital stay was longer for patients with diabetes vs. non-diabetic patients, but there was no difference in deaths between the two groups (p = 0.797).

CONCLUSION

Patients with diabetes undergoing CABG develop more infectious diseases and stay longer in hospital than non-diabetics.

Does duration of perioperative antibiotic prophylaxis matter in cardiac surgery? A systematic review and meta-analysis

OBJECTIVE

We aimed to compare the efficacy of short-term (<24 hours) versus longer-term antibiotic prophylaxis (≥24 hours) in open heart surgery.

BACKGROUND

The optimal duration of antibiotic prophylaxis for adults undergoing cardiac surgery is unknown and guideline recommendations are inconsistent.

METHODS

We searched MEDLINE, EMBASE, CINAHL, and CENTRAL for parallel-group randomized trials comparing any antibiotic prophylaxis administered for <24 hours to any antibiotic prophylaxis for ≥24 hours in adult patients undergoing open heart surgery. Reference lists of selected articles, clinical practice guidelines, review articles, and congress abstracts were searched. Study selection, data extraction and assessment of risk of bias were performed independently by 2 reviewers.

RESULTS

Of the 1338 citations identified by our search strategy, 12 studies involving 7893 patients were selected. Compared with short-term antibiotic prophylaxis, longer-term antibiotic prophylaxis reduced the risk of sternal surgical site infection (SSI) by 38% (risk ratio 1.38, 95% confidence interval (CI) 1.13-1.69, P = 0.002) and deep sternal SSI by 68% (risk ratio 1.68, 95% CI 1.12-2.53, P = 0.01). There were no statistically significant differences in mortality, infections overall and adverse events. Eleven of the trials were at high risk for bias due to limitations in study design.

CONCLUSIONS

Perioperative antibiotic prophylaxis of ≥24 hours may be more efficacious in preventing sternal SSIs in patients undergoing cardiac surgery compared to shorter regimens. The findings however are limited by the heterogeneity of antibiotic regimens used and the risk of bias in the published studies.

[Hospital infections at the Department of Cardiovascular Surgery]

INTRODUCTION

Despite modern surgical techniques, preoperative preventive use of antibiotics and optimal treatment of operative site, patients who underwent surgical procedures are still at a risk of developing hospital infections. The aim of this paper was to estimate the frequency of hospital infections at the Department of Cardiovascular Surgery and their presence according to the anatomic localization as well as to identify the most frequent causes of hospital infections.

MATERIAL AND METHODS

During one-year period, all surgically treated patients were prospectively followed at the Department of Cardiovascular Surgery of the Institute of Cardiovascular Diseases, Vojvodina. There were 1302 patients who underwent 1396 surgical procedures during the period observed The descriptive epidemiological method was applied in the study. The following odds ratio and rates were calculated: the incidence rate of patients with hospital infections, the incidence rate of hospital infections and the incidence rate in relation to hospital stay of each patient (incidence density).

RESULTS

During that period, 36 hospital infections were recorded in 33 patients. The average incidence rate of patients with hospital infection was 2.53% and hospital infection rate was 2.58% (from 0% to 5.13%). The male-female ratio was 3.1:1. The most frequent hospital infections were surgical site infections (incidence rate 0.86%), then gastroenteritis (incidence rate 0.77%) and bloodstream infections (incidence rate 0.46%). The most common causes of hospital infections were: Staphylococcus aureus (14.8%), Acinetobacter spp (22.2%) and coagulase negative staphylococcus (11.1%).

CONCLUSION

The fact is that the incidence rate of hospital infections is relatively low, and such a trend can continue only if the continuous epidemiological control and preventive measures are implemented in the future.

Isolated coronary artery bypass grafting in obese individuals: a propensity matched analysis of outcomes

BACKGROUND

There is conflicting data regarding the impact of obesity on morbidity and mortality in patients undergoing isolated coronary artery bypass grafting (CABG).

METHODS AND RESULTS

Retrospective cohort analysis of patients who underwent CABG from January 1, 1995, through July 31, 2010 was performed. Patients were classified as obese or non-obese (body mass index ≥ 30.0 kg/m(2) and <30.0 kg/m(2), respectively). The primary outcome was in-hospital mortality. Secondary outcomes included postoperative respiratory failure, postoperative stroke, postoperative myocardial infarction, sternal and leg wound infections, postoperative atrial fibrillation, postoperative ventricular tachycardia, postoperative renal failure and length of hospital stay. Propensity-matched stepwise multivariable logistic regression was performed. Of 13,115 patients, 4,619 (35.2%) were obese. In the propensity-matched logistic regression models (n = 8,442), obesity was not associated with postoperative mortality (odds ratio = 1.13, 95% confidence interval 0.86-1.48). However, obesity was associated with postoperative respiratory failure, postoperative renal insufficiency, sternal wound infection, and leg wound infection. Obesity was also associated with a decreased risk of postoperative bleeding and re-operation from bleeding.

CONCLUSIONS

Obesity was associated with an increased risk of postoperative respiratory failure, postoperative renal failure, and surgical site infections. However, obesity was not associated with in-hospital mortality in patients undergoing CABG.

Prospective, open-label investigation of the pharmacokinetics of daptomycin during cardiopulmonary bypass surgery

As methicillin-resistant Staphylococcus aureus (MRSA) becomes more prevalent, vancomycin is becoming increasingly used as a prophylaxis against surgical-site infections for cardiothoracic surgeries. However, vancomycin administration can be challenging, and the pharmacokinetics of alternative antibiotics in this setting are poorly understood. The primary objective of this investigation was to describe the pharmacokinetics of daptomycin in patients undergoing coronary artery bypass graft surgery. We enrolled 15 patients undergoing coronary artery bypass surgery requiring cardiopulmonary bypass. Each subject was administered a single open-label dose of daptomycin (8 mg/kg of body weight) for surgical prophylaxis. Fourteen daptomycin plasma samples were collected. Safety outcomes between subjects who received daptomycin and 15 control subjects who received the standard-of-care antibiotic were compared. The mean maximal concentration of daptomycin (C(max)) was 84.4 ± 27.1 μg/ml; the mean daptomycin concentration during the cardiopulmonary bypass procedure was 33.2 ± 11.4 μg/ml and was 30.9 ± 12.7 μg/ml at sternum closure. Mean daptomycin concentrations at 12, 18, 24, and 48 h were 22.7 ± 9.7, 16.2 ± 8.2, 12.0 ± 4.7, and 3.5 ± 2.3 μg/ml, respectively. Mean daptomycin concentrations were consistently above the MIC at which 90% of the tested isolates are inhibited (MIC₉₀) for S. aureus and S. epidermidis during the cardiopulmonary bypass procedure. Daptomycin was not associated with surgical-site infections or differences in adverse events compared to findings for control subjects. We found that a single dose of daptomycin at 8 mg/kg was well tolerated and achieved adequate plasma concentrations against common pathogens associated with surgical-site infections after cardiothoracic surgery. Daptomycin may be considered an alternative surgical prophylaxis antibiotic for patients undergoing cardiothoracic bypass surgery who are unable to receive vancomycin.