Outcome and Risk Factors Associated with Surgical Site Infections After Cardiac Surgery in a Taiwan Medical Center

Risk Factors for Surgical Site Infections After Single-Level Anterior Lumbar Interbody Fusion

Abstract Background: Anterior lumbar interbody fusion (ALIF) has become an increasingly popular and effective treatment modality for various conditions of the lumbar spine. However, complications after this procedure can be costly. Surgical site infections (SSIs) are one of these types of complications. The present study identifies independent risk factors for SSI after single-level ALIF to identify high-risk patients better. Patients and Methods: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was queried to identify single-level ALIF patients from 2005 to 2016. Multilevel fusions and non-anterior approach procedures were excluded. Mann-Pearson χ² tests analyzed categorical variables, whereas one-way analysis of variance (ANOVA) and independent t-tests analyzed differences in mean values of continuous variables. Risk factors for SSI were identified via a multivariable logistic regression model. A receiver operating characteristic (ROC) curve was generated utilizing the predicted probabilities. Results: A total of 10,017 patients met inclusion criteria; 80 (0.80%) had developed SSI and 9,937 (99.20%) had not. On multivariable logistic regression models, class 3 obesity (p = 0.014), dialysis (p = 0.025), long-term steroid use (p = 0.010), and wound classification 4 (dirty/infected) (p = 0.002) all independently increased the risk for SSI in single-level ALIF. The area under the receiver operating characteristic curve (AUROC; C-statistic) was 0.728 (p < 0.001), indicating relatively strong reliability of the final model. Conclusions: Several independent risk factors including obesity, dialysis, long-term steroid use, and dirty wound classification all increased risk for SSI after single-level ALIF. By identifying these high-risk patients, surgeons and patients can have more informed pre-operative discussions. In addition, identifying and optimizing these patients prior to operative intervention may help to minimize infection risk.

Validation of ventral hernia risk score in predicting surgical site infections

PURPOSE

Ventral hernia risk score (VHRS) is a risk assessment tool for predicting the development of surgical site infection (SSI) developed in the Veterans Affairs population by Berger et al. The score was externally validated by the same study group in a diverse population in another study. It was also shown to be better than the existing Centre for Diseases (CDC) wound class and Ventral Hernia Working Group (VHWG) models. Our study aims to test the performance of the score in an Asian-Indian population.

METHODS

A prospective database of ventral hernia repairs done in a tertiary care centre between February 2019 and December 2020 was utilized for the study. All patients with a minimum follow-up of 1-month period were included in the study. The CDC definition of SSI was used. The VHRS, VHWG, and CDC class of each of the patients was determined. Receiver-Operating curves (ROC) of the scores and area under the curves (AUC) were used to compare the three scores.

RESULTS

A total of 120 patients were included. During the course of our study, a total of 33 patients developed SSI (27.5%). Important factors which seemed to predict SSI were median operating time, CDC incision class, concomitant hernia repair, and creating skin flaps. The AUC of the VHRS score was 0.76 which was higher than those of VHWG (0.61) and CDC (0.58).

CONCLUSION

Our study externally validates the novel VHRS which outperforms both CDC incision class and VHWG in predicting SSI following open ventral hernia repair, especially in a group with lower BMI compared to the previous reports. Trial registration No CTRI/2020/07/026289 registered on 01/07/2020.

Establishment and Validation of a Nomogram to Predict Hospital-Acquired Infection in Elderly Patients After Cardiac Surgery

Background

Hospital-acquired infection (HAI) after cardiac surgery is a common clinical concern associated with adverse prognosis and mortality. The objective of this study is to determine the prevalence of HAI and its associated risk factors in elderly patients following cardiac surgery and to build a nomogram as a predictive model.

Methods

We developed and internally validated a predictive model from a retrospective cohort of 6405 patients aged ≥70 years, who were admitted to our hospital and underwent cardiac surgery. The primary outcome was HAI. Multivariable logistic regression analysis was used to identify independent factors significantly associated with HAI. The performance of the established nomogram was assessed by calibration, discrimination, and clinical utility. Internal validation was achieved by bootstrap sampling with 1000 repetitions to reduce the overfit bias.

Results

Independent factors derived from the multivariable analysis to predict HAI were smoking, myocardial infarction, cardiopulmonary bypass use, intraoperative erythrocytes transfusion, extended preoperative hospitalization days and prolonged duration of mechanical ventilation postoperatively. The derivation model showed good discrimination, with a C-index of 0.706 [95% confidence interval 0.671–0.740], and good calibration [Hosmer–Lemeshow test P = 0.139]. Internal validation also maintained optimal discrimination and calibration. The decision curve analysis revealed that the nomogram was clinically useful.

Conclusions

We developed a predictive nomogram for postoperative HAIs based on routinely available data. This predictive tool may enable clinicians to achieve better perioperative management for elderly patients undergoing cardiac surgery but still requires further external validation.

The association between preoperative length of hospital stay and deep sternal wound infection: A scoping review

BACKGROUND

Deep sternal wound infection (DSWI) is a serious complication of cardiac surgery, associated with a significantly longer hospital stay, an increased mortality, and an almost doubling of treatment costs. The preoperative length of hospital stay has been suggested in a small number of studies as a modifiable risk factor yet is not included in surgical site infection prevention guidelines. The aim of this scoping review was to review the existing evidence on the association between preoperative length of hospital stay and DSWI, and to identify established risk factors for DSWI.

METHODS

A literature search of six electronic databases yielded 2297 results. Titles concerning risk factors for DSWI, sternal or surgical wound infection, or poststernotomy complications were included. Abstracts relating to preoperative length of stay as a risk factor for DSWI proceeded to full article review. Articles regarding paediatric surgery, DSWI management or unavailable in English were excluded.

RESULTS

The review identified 11 observational cohort studies. DSWI prevalence was between 0.9% and 6.8%. Preoperative length of stay ranged from 0-15.5 days and was found to be associated with DSWI in all studies. Preoperative length of stay and DSWI were inconsistently defined. Other risk factors for DSWI included diabetes, obesity, respiratory disease, heart failure, renal impairment, complex surgery, and reoperation (p < 0.05).

CONCLUSION

In this scoping review, an association between preoperative length of stay and the development of DSWI following cardiac surgery was identified. Thus, preoperative length of stay as a modifiable risk factor for DSWI should be considered for inclusion in cardiothoracic surgical infection prevention guidelines.

Higher Surgery and Recovery Room Air Pressures Associated with Reduced Surgical Site Infection Risk

BACKGROUND

Incisional surgical site infections (SSIs) following coronary artery bypass grafting (CABG) prolong hospital stays, elevate healthcare costs and increase likelihood of further complications. High air pressure deactivates bacteria and is utilized for commercial food preservation, assuring microbiologically safe pharmaceuticals and sanitizing instruments. However, research on utilizing air pressure deactivation thresholds in surgical and postoperative rooms to reduce rates of SSIs is lacking.

METHODS

A case-control study of 801 CABG patients, 128 SSI cases and 673 controls was conducted from January 1, 2006 through March 31, 2009 in Yerevan, Armenia. Patient and surgery characteristics, air pressure measurements and seasons were selected as independent variables with SSI rates as the outcome. The novel threshold regression analysis was used to determine potential air pressure bacterial deactivation thresholds. A final multivariate logistic regression model adjusted for confounders.

RESULTS

Overall, bacterial deactivation air pressure threshold was 694.2 mmHg, with the presence of infection for higher air pressure values not statistically significant from zero. Individual deactivation thresholds for Staphylococcus epidermidis (threshold = 694.2 mmHg) and Escherichia coli (threshold = 689.2) showed similar patterns. Multivariate logistic regression showed air pressure above the deactivation threshold was highly protective against SSIs with adjOR = 0.27 (p-value = 0.009, 95%CI: 0.10-0.72). Other SSI risk factors included female sex, adjOR = 2.12 (p-value = 0.006, 95%CI: 1.24-3.62), diabetes, adjOR = 2.61 (p-value < 0.001, 95%CI: 1.72-3.96) and longer time on ventilator, adjOdds = 1.01 (p-value = 0.012, 95%CI: 1.00-1.02).

CONCLUSION

Maintaining air pressures in operating and postoperative rooms exceeding bacterial-deactivation thresholds might substantially reduce SSI rates following surgery. Further research should identify specific bacterial-deactivation air pressure thresholds in surgical and postoperative rooms to reduce SSI rates, especially for drug-resistant bacteria.

Bilateral-pectoral major muscle advancement flap combined with vacuum-assisted closure therapy for the treatment of deep sternal wound infections after cardiac surgery

Objectives

The median sternotomy is the most common surgical approach for cardiac surgery. Deep sternal wound infection is a fatal complication after median sternotomy. The aim of this study was to evaluate the therapeutic effect of Bilateral-pectoral major muscle advancement flap combined with Vacuum-assisted closure therapy on rehabilitation for the treatment of deep sternal wound infection after cardiac surgery.

Methods

Between January 2016 to January 2018, 21 patients (10 males, 11 females) with deep sternal wound infection after cardiac surgery underwent Bilateral-pectoral major muscle advancement flap combined with Vacuum-assisted closure therapy. These patients were followed-up 12 months postoperative. The patient characteristics, duration of vacuum-assisted closure therapy, the mean hospital stay, postoperative complications, long-term survival of patients were retrospectively analyzed.

Results

Most patients undergone 1–3 times vacuum-assisted closure treatment sessions before closure. All patients were cured to discharge, the mean hospital stay was 21.1 days. Most patients’ healing wounds were first-stage healing, only one patient’s wound was second-stage healing, none was third-stage healing. One patient developed pulmonary infection and respiratory failure during the 12-month follow-up. None of the patients died during follow-up.

Conclusions

Bilateral-pectoral major muscle advancement flap combined with Vacuum-assisted closure therapy for the treatment of deep sternal wound infections after cardiac surgery can shorten the hospital stays and few complications. However, this is a retrospective case series presentation with no comparison group, the number of inferences is limited, so further large-scale controlled studies are needed.

Surgical Site Infection Risk Factor Analysis in Postbariatric Patients Undergoing Body Contouring Surgery: A Nested Case-Control Study

BACKGROUND

Surgical site infections (SSIs) following body-contouring plastic surgery pose a significant burden on patients and caregivers, possibly leading to undesired surgical outcomes. Surgical site infection incidence following body-contouring plastic surgery ranges from 2% to 7%, but is estimated much higher among postbariatric massive weight loss (MWL) patients.

OBJECTIVE

The aim of this study was to evaluate SSI rate, risk and protective factors among postbariatric MWL patients following body-contouring plastic surgery.

METHODS

This was a nested case-control study of MWL patients who underwent body-contouring plastic surgery at the Department of Plastic Surgery at Assaf Harofeh Medical Center, between 2007 and 2014. Data were obtained from medical records. Surgical site infection was defined according to the Centers for Disease Control and Prevention criteria. Logistic regression was conducted to assess independent risk factors for SSIs.

RESULTS

From a cohort of 172 patients, 86 were included in the study. Surgical site infection rate was 20% (n = 17). Significant SSI risk factors included lifetime maximal weight and lifetime maximal body mass index (P = 0.039 and P = 0.002, respectively), body mass index loss prior to surgery (P = 0.032), estimated blood loss during surgery (P = 0.002), and gynecomastia repair procedure (P = 0.038). Independent SSI-associated factors included thigh lift procedure (odds ratio, 4.66; 95% confidence interval, 1.13-19.28) and preoperative antimicrobial prophylaxis (odds ratio, 0.04; 95% confidence interval, 0.03-0.61).

CONCLUSIONS

Although not required by current guidelines for body-contouring plastic surgery, preoperative antimicrobial prophylaxis in our study demonstrated a significant protective effect against SSIs. Further research may reveal its true contribution to SSI prevention in body-contouring plastic surgery.

Surgical site infection in elective clean and clean-contaminated surgeries in developing countries

BACKGROUND

Surgical site infection (SSI) is both the most frequently studied healthcare-associated infection and the most common healthcare-associated infection in the developing world. A systematic review and meta-analysis was conducted to evaluate the relative size of this burden and to estimate the prevalence of SSI in clean and clean-contaminated surgeries in a large sample of countries in the developing world.

METHODS

A systematic search of the MEDLINE/PubMed, Scopus, and LILACS databases was conducted to identify studies providing the prevalence of SSI in elective clean and clean-contaminated surgeries in 39 countries or regions around the world. Data of interest were limited to publications from January 2000 to December 2017. Studies with information on the number of cases of SSI and number of total elective clean and clean-contaminated surgeries during the same period were included in this evaluation. Studies lacking clear definition of the total number of exposed patients were excluded.

RESULTS

Based on the combined data from the 99 articles evaluated in this analysis, the overall prevalence of SSI in elective clean and clean-contaminated surgeries was estimated to be 6% (95% confidence interval (CI) 5-7%). This increased to 15% (95% CI 6-27%) when considering only those reports with post-discharge surveillance data. The overall prevalence of SSI in Africa/Middle East, Latin America, Asia, and China was 10% (95% CI 6-15%), 7% (95% CI 5-10%), 4% (95% CI 4-5%), and 4% (95% CI 2-6%), respectively. Significant variability in the data was confirmed by both the funnel plot and the Egger test (p=0.008).

CONCLUSIONS

Although the data are variable, it is clear that the incidence of SSI in the developing world is higher than that in the developed world.

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.

Nosocomial infections and antibiotic resistance pattern in open-heart surgery patients at Imam Ali Hospital in Kermanshah, Iran

Background: Patients undergoing open heart surgery have a relatively high risk of acquiring nosocomial infections. The development of antibiotic-resistant infections is associated with prolonged hospital stays and mortalities.

Objectives: The present study was conducted to investigate nosocomial infections and the antibiotic resistance pattern in bacteria causing these infections in open heart surgery patients at Imam Ali Hospital in Kermanshah in the west of Iran over a 4-year period from March 2011 to March 2014.

Materials and methods: The present cross-sectional study was conducted on 135 cases of nosocomial infection among open heart surgery patients. The demographic characteristics and the risk factors of each case of infection were recorded. The antibiotic susceptibility test was carried out using the Minimum Inhibitory Concentration (MIC) method based on the Clinical and Laboratory Standards Institute (CLSI) protocol. The data collected were then analyzed in SPSS-16.

Results: Out of the 6,000 patients who underwent open heart surgery during this 4-year period at the selected hospital, nosocomial infections developed in 135 patients (2.25%), 59.3% of whom were female and 40.7% male. Surgery site infection (SSI), pneumonia (PNEU), urinary tract infection (UTI) and blood stream infection (BSI) affected 52.6%, 37%, 9.6% and 0.8% of the cases, respectively. E.coli, Klebsiella spp. and S. aureus were the most common bacteria causing the nosocomial infections. E. coli was most frequently resistant to imipenem (23.3%) Klebsiella spp. to gentamicin (38.5%) S. aureus to co-trimoxazole (54.2%).

Conclusion: SSI had a high prevalence in this study. Further studies should therefore be conducted to examine the risk factors associated with SSI in open heart surgery. Various studies have shown that antibiotic resistance patterns are different in different regions. Finding a definitive treatment therefore requires an antibiogram.

Resistance Pattern of Antibiotics in Patient Underwent Open Heart Surgery With Nosocomial Infection in North of Iran

Background:

Patients who undergo cardiac surgery appear to be at increased risk for the development of Nosocomial infections (NIs). The development of antibiotic-resistant infections has been associated with significantly greater hospital mortality rates compared to similar infections caused by antibiotic-sensitive pathogens.

Objectives:

The purpose of this study is survey of Nis and antibiotic resistance patterns of causative bacteria among patients who underwent open heart surgery in the north of Iran during a 2-year period between September 2012 and September 2014.

Methods:

In this cross-sectional study we evaluated 187 patients that underwent open heart surgery with NIs. Demographic feature, clinical characteristics and risk factors of each infection were recorded. The antibiotic susceptibility test was performed using the Minimum inhibitory concentration (MIC) method according to the standard protocol of Clinical & Laboratory Standards Institute (CLSI). Detection of Extended-spectrum beta-lactamase (ESBL) producing bacteria was performed by the double-disk synergy (DDS) test; also Methicillin-resistant Staphylococcus (MRSA) strains were identified by MRSA Screen Agar. The collected data were analyzed using the SPSS software (ver. 16) and, descriptive statistics were used.

Results:

Out Of total of 2253 hospitalized patients who underwent open heart surgery, 187(5.05%) patients had NIs. 51.9% of the patients were female. The rates of surgical site infection (SSI), respiratory tract infection, endocarditis, Urinary tract infection (UTI), blood Infection and mediastinitis were 27.80, 25.66%, 17.64, 17.11% 8.55% and 3.20% respectively. E.coli and S.aureus were the most causative agents of NIs. The rate of ESBL-producing bacteria was 14.28- 71.42% among enterobacteriaceae and the rate of MRSA was 54.2% among S.aureus strains. All isolated Acinetobacter.spp were Multi-drug resistance (MDR).

Conclusions:

We showed that the rate of NIs among these high-risk patients was in the average level. But the emergence of MRSA and ESBL bacteria is increasing in our region.

The role of patient's profile and allogeneic blood transfusion in development of post-cardiac surgery infections: a retrospective study

OBJECTIVES

We aimed to investigate the association of patient characteristics and allogeneic blood transfusion products in development of post-cardiac surgery nosocomial infections.

METHODS

This retrospective study was conducted in 7888 patients undergoing cardiac surgery with median sternotomy and cardiopulmonary bypass. Multivariable logistic regression analysis was used for independent effect of variables on infections.

RESULTS

A total of 970 (12.3%) patients developed one or several types of postoperative infections. Urinary (n = 351, 4.4%) and pulmonary tract infections (n = 478, 6.1%) occurred more frequently than sternal wound infections (superficial: n = 102, 1.3%, deep: n = 72, 0.9%) and donor site infections (n = 61, 0.8%). Interventions, including valve replacement (P = 0.002) and coronary artery bypass grafting combined with valve replacement (P = 0.012), were associated with increased risk of several types of postoperative infections. Patients' profiles changed substantially over the years; morbid obesity (P = 0.019), smoking (P = 0.001) and diabetes mellitus (P = 0.001) occur more frequently nowadays. Furthermore, surgical site infections showed to be related to morbid obesity (P < 0.001) and higher risk stratification (P = 0.031). Smoking (P < 0.001) and chronic obstructive pulmonary disease (P < 0.001) were related to pulmonary tract infections. In addition, diabetic patients developed more sepsis (P = 0.003) and advanced age was associated with development of urinary tract infections (P < 0.001). Even after correcting for other factors, blood transfusion was associated with all types of postoperative infection (P < 0.001). This effect remained present in both leucocyte-depleted and non-leucocyte-depleted transfusion.

CONCLUSIONS

Our data showed that post-cardiac surgery infections occur more frequently in patients with predetermined risk factors. The amount of blood transfusions was integrally related to every type of postoperative infection.