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1.  Incidence and predictors of surgical site infections following caesarean sections at Bugando Medical Centre, Mwanza, Tanzania 
Surgical site infection (SSI) is the second most common infectious complication after urinary tract infection following a delivery by caesarean section (CS). At Bugando Medical Centre there has no study documenting the epidemiology of SSI after CS despite the large number of CSs performed and the relatively common occurrence of SSIs.
This was a prospective cohort study involving pregnant women who underwent a CS between October 2011 and February 2012 at Bugando Medical Centre. A total of 345 pregnant women were enrolled. Preoperative, intraoperative and postoperative data were collected using a standardized questionnaire. Wound specimens were collected and processed as per standard operative procedures; and susceptibility testing was carried out using a disc diffusion technique. Data was analyzed using STATA version 11.
The overall cumulative incidence of SSI was 10.9% with an incidence rate of 37.5 per 10,000 people/day (95% CI, 26.8-52.4). The median time from CS to the development of SSI was 7 days (interquartile range [IQR] = 6–9 days). Six independent risk factors for post caesarean SSI as identified in this study by multivariate analysis are: hypertensive disorders of pregnancy (HR: 2.5; 95% CI, 1.1-5.6; P = 0.021), severe anaemia (HR: 3.8; 95% CI, 1.2-12.4, P = 0.028), surgical wound class III (HR: 2.4; 95% CI, 1.1-5.0; P = 0.021), multiple vaginal examinations (HR: 2.5; 95% CI, 1.2-5.1; P = 0.011), prolonged duration of operation (HR: 2.6; 95% CI, 1.2-5.5; P = 0.015) and an operation performed by an intern or junior doctor (HR: 4.0; 95% CI, 1.7-9.2; P = 0.001). Staphylococcus aureus was the most common organism (27.3%), followed by Klebsiella pneumoniae (22.7%). Patients with a SSI had a longer average hospital stay than those without a SSI (12.7 ± 6.9 vs. 4 ± 1.7; P < 0.0001) and the case fatality rate among patients with a SSI was 2.9%.
SSIs are common among women undergoing CSs at Bugando Medical Centre. SSIs were commonly associated with multiple factors. Strategies to control these factors are urgently needed to control SSIs post CS at Bugando Medical Centre and other centres in developing countries.
PMCID: PMC4131772  PMID: 25126415
2.  Comparison of Two Computer Algorithms To Identify Surgical Site Infections 
Surgical Infections  2011;12(6):459-464.
Surgical site infections (SSIs), the second most common healthcare-associated infections, increase hospital stay and healthcare costs significantly. Traditional surveillance of SSIs is labor-intensive. Mandatory reporting and new non-payment policies for some SSIs increase the need for efficient and standardized surveillance methods. Computer algorithms using administrative, clinical, and laboratory data collected routinely have shown promise for complementing traditional surveillance.
Two computer algorithms were created to identify SSIs in inpatient admissions to an urban, academic tertiary-care hospital in 2007 using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes (Rule A) and laboratory culture data (Rule B). We calculated the number of SSIs identified by each rule and both rules combined and the percent agreement between the rules. In a subset analysis, the results of the rules were compared with those of traditional surveillance in patients who had undergone coronary artery bypass graft surgery (CABG).
Of the 28,956 index hospital admissions, 5,918 patients (20.4%) had at least one major surgical procedure. Among those and readmissions within 30 days, the ICD-9-CM-only rule identified 235 SSIs, the culture-only rule identified 287 SSIs; combined, the rules identified 426 SSIs, of which 96 were identified by both rules. Positive and negative agreement between the rules was 36.8% and 97.1%, respectively, with a kappa of 0.34 (95% confidence interval [CI] 0.27–0.41). In the subset analysis of patients who underwent CABG, of the 22 SSIs identified by traditional surveillance, Rule A identified 19 (86.4%) and Rule B identified 13 (59.1%) cases. Positive and negative agreement between Rules A and B within these “positive controls” was 81.3% and 50.0% with a kappa of 0.37 (95% CI 0.04–0.70).
Differences in the rates of SSI identified by computer algorithms depend on sources and inherent biases in electronic data. Different algorithms may be appropriate, depending on the purpose of case identification. Further research on the reliability and validity of these algorithms and the impact of changes in reimbursement on clinician practices and electronic reporting is suggested.
PMCID: PMC3279712  PMID: 22136489
3.  Cesarean Section Surgical Site Infections in Sub-Saharan Africa: A Multi-Country Study from Medecins Sans Frontieres 
World Journal of Surgery  2014;39:350-355.
Surgical site infections (SSI) are a significant cause of post-surgical morbidity and mortality and can be an indicator of surgical quality. The objectives of this study were to measure post-operative SSI after cesarean section (CS) at four sites in three sub-Saharan African countries and to describe the associated risk factors in order to improved quality of care in low and middle income surgical programs.
This study included data from four emergency obstetric programs supported by Medecins sans Frontieres, from Burundi, the Democratic Republic of Congo (DRC), and Sierra Leone. Women undergoing from August 1 2010 to January 31 2011 were included. CS post-operative SSI data were prospectively collected. Logistic regression was used to model SSI risk factors.
In total, 1,276 women underwent CS. The incidence of SSI was 7.3 % (range 1.7–10.4 %). 93 % of SSI were superficial. The median length of stay of women without SSI was 7 days (range 3–63 days) compared to 21 days (range 5–51 days) in those with SSI (p < 0.001). In multivariate analysis, younger age, premature rupture of the membranes, and neonatal death were associated with an increased risk of SSI, while antenatal hemorrhage and the Lubutu, DRC project site were associated with a lower risk of developing an SSI.
This study demonstrates that surgery can be performed with a low incidence of SSI, a proxy for surgical safety, in sub-Saharan Africa. Protocols such as perioperative antibiotics and basic infrastructure such as clean water and sterilization can be achieved. Simple data collection tools will assist policymakers with monitoring and evaluation as well as quality control assurance of surgical programs in low and middle income countries.
PMCID: PMC4300431  PMID: 25358418
4.  Implementation of a Bundle of Care to Reduce Surgical Site Infections in Patients Undergoing Vascular Surgery 
PLoS ONE  2013;8(8):e71566.
Surgical site infections (SSI’s) are associated with severe morbidity, mortality and increased health care costs in vascular surgery.
To implement a bundle of care in vascular surgery and measure the effects on the overall and deep-SSI’s rates.
Prospective, quasi-experimental, cohort study.
A prospective surveillance for SSI’s after vascular surgery was performed in the Amphia hospital in Breda, from 2009 through 2011. A bundle developed by the Dutch hospital patient safety program (DHPSP) was introduced in 2009. The elements of the bundle were (1) perioperative normothermia, (2) hair removal before surgery, (3) the use of perioperative antibiotic prophylaxis and (4) discipline in the operating room. Bundle compliance was measured every 3 months in a random sample of surgical procedures and this was used for feedback.
Bundle compliance improved significantly from an average of 10% in 2009 to 60% in 2011. In total, 720 vascular procedures were performed during the study period and 75 (10.4%) SSI were observed. Deep SSI occurred in 25 (3.5%) patients. Patients with SSI’s (28,5±29.3 vs 10.8±11.3, p<0.001) and deep-SSI’s (48.3±39.4 vs 11.4±11.8, p<0.001) had a significantly longer length of hospital stay after surgery than patients without an infection. A significantly higher mortality was observed in patients who developed a deep SSI (Adjusted OR: 2.96, 95% confidence interval 1.32–6.63). Multivariate analysis showed a significant and independent decrease of the SSI-rate over time that paralleled the introduction of the bundle. The SSI-rate was 51% lower in 2011 compared to 2009.
The implementation of the bundle was associated with improved compliance over time and a 51% reduction of the SSI-rate in vascular procedures. The bundle did not require expensive or potentially harmful interventions and is therefore an important tool to improve patient safety and reduce SSI’s in patients undergoing vascular surgery.
PMCID: PMC3742500  PMID: 23967222
5.  Risk Factors for Surgical Site Infection Following Major Breast Surgery 
Surgical site infections following breast surgery result in increased length of hospital stay, antibiotic utilization, and morbidity. Understanding SSI risk factors is essential to develop infection prevention strategies and improve surgical outcomes.
A retrospective case-control design was used to determine independent risk factors for surgical site infection in subjects selected from a cohort of patients who had mastectomy, breast reconstruction or reduction surgery between January 1998 and June 2002 at a tertiary-care university affiliated hospital. SSI cases within 1 year after surgery were identified using ICD-9-CM diagnosis codes for wound infection or complication and/or positive wound cultures. The medical records of 57 case patients with breast SSI and 268 randomly selected uninfected control patients were reviewed. Multivariate logistic regression was used to identify independent risk factors for SSI.
During the 4.5-year study period, 57 patients developed SSIs involving a breast incision and 10 patients developed SSIs involving a donor site incision. Significant independent risk factors for SSI involving the breast incision included insertion of a breast implant or tissue expander (odds ratio (OR) 5.3, 95% confidence interval (CI):2.5–11.1), suboptimal prophylactic antibiotic dosing (OR 5.1, 95% CI: 2.5–0.2 ), transfusion (OR 3.4, 95% CI: 1.3–9.0), mastectomy (OR 3.3, 95% CI: 1.4–7.7), previous chest irradiation (OR 2.8, 95% CI: 1.2–6.5), and current or recent smoking (OR 2.1, 95% CI: 0.9–4.9). Local infiltration of an anesthetic agent was associated with significantly reduced risk of SSI (OR 0.4, 95% CI: 0.1–0.9).
Suboptimal prophylactic antibiotic dosing is a potentially modifiable risk factor for SSI following breast surgery. Risk of SSI was increased in patients undergoing mastectomy and in patients who had an implant or tissue expander placed during surgery. Knowledge of these risk factors can be used to develop a specific risk stratification index to predict SSI in breast surgery and infection preventive strategies tailored for breast surgery patients.
PMCID: PMC3618680  PMID: 18722936
6.  The epidemiology and cost of surgical site infections in Korea: a systematic review 
To conduct a systematic literature review of the epidemiological and economic burden of surgical site infection (SSI) in Korea.
A search of the EMBASE, Medline and KoreaMed databases for English and Korean language publications was conducted. Searches for epidemiological and economic studies were conducted separately and limited to 1995 to 2010 to ensure the pertinence of the data.
Twenty-six studies were included. The overall incidence of SSI in Korea was 2.0 to 9.7%. The National Nosocomial Infections Surveillance risk index was positively correlated with the risk of developing an SSI. Specific risk factors for SSI, identified through multivariate analyses included; diabetes, antibiotic prophylaxis and wound classification. SSIs were associated with increased hospitalisation cost, with each episode of SSI estimated to cost about an additional ₩2,000,000. A substantial portion of the increased cost was attributed to hospital room costs and the need for additional medication. Studies also found that post-operative stays for patients with SSIs were 5 to 20 days longer, while two studies reported that following cardiac surgery, patients with SSIs spent an additional 5 to 11 days in the intensive care unit, compared to patients without SSIs.
Data from the included studies demonstrate that SSI represents a significant clinical and economic burden in Korea. Consequently, the identification of high-risk patient populations and the development of strategies aimed at reducing SSI may lead to cost-savings for the healthcare system.
PMCID: PMC3228997  PMID: 22148121
Surgical site infection; Epidemiology; Cost
7.  Does Minimally Invasive Surgery Have a Lower Risk of Surgical Site Infections Compared With Open Spinal Surgery? 
Surgical site infection (SSI) ranges from 1.9% to 5.5% in most large series. Minimally invasive surgery (MIS) has been postulated to reduce SSI rates.
(1) Is MIS associated with a lower incidence of SSI compared with open spinal surgery? (2) Are there other independent risk factors associated with SSI? (3) What bacteria are most common in spinal SSI?
Medical records of 2299 patients who underwent transforaminal lumbar interbody fusion, laminectomy, or discectomy were analyzed and selected for a nested case-control analysis. Twenty-seven cases with SSI were matched with 162 control subjects without SSI stratified based on procedure performed within 28 days of the case’s date of surgery. Patients were identified from an institutional database at a tertiary care hospital. MIS involved spinal procedures performed through a tubular retractor system. Univariate and multivariate analyses were performed.
Patients undergoing open spinal surgery were 5.77 times more likely to develop SSI compared with MIS approaches (odds ratio [OR], 5.77; 95% confidence interval [CI], 1.0–32.7; p = 0.048). Also, from the multivariate regression model, diabetes (OR, 4.7; 95% CI, 1.3–17.0; p = 0.018), number of levels operated on (OR, 3.5; 95% CI, 1.6–7.5; p = 0.001), and body mass index (OR, 1.2; 95% CI, 1.0–1.3; p = 0.010) were predictive of an increased risk in SSI. Staphylococcus aureus was most frequently identified, being present in 12 of 21 (52.4%) patients in whom positive cultures were obtained. Four of the 12 patients had methicillin-resistant S aureus infection.
In our series, MIS has a lower incidence of SSI. The risk factors predictive of SSI should be further evaluated in well-designed prospective trials.
Level of Evidence
Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC4016449  PMID: 23846605
8.  Improving Public Reporting and Data Validation for Complex Surgical Site Infections After Coronary Artery Bypass Graft Surgery and Hip Arthroplasty 
Open Forum Infectious Diseases  2014;1(3):ofu106.
Diagnosis codes in claims submitted for reimbursement following coronary artery bypass graft surgery and hip arthroplasty allow standardized and efficient identification of deep and organ/space surgical site infections.
 Deep and organ/space surgical site infections (D/OS SSI) cause significant morbidity, mortality, and costs. Rates are publicly reported and increasingly used as quality metrics affecting hospital payment. Lack of standardized surveillance methods threaten the accuracy of reported data and decrease confidence in comparisons based upon these data.
 We analyzed data from national validation studies that used Medicare claims to trigger chart review for SSI confirmation after coronary artery bypass graft surgery (CABG) and hip arthroplasty. We evaluated code performance (sensitivity and positive predictive value) to select diagnosis codes that best identified D/OS SSI. Codes were analyzed individually and in combination.
 Analysis included 143 patients with D/OS SSI after CABG and 175 patients with D/OS SSI after hip arthroplasty. For CABG, 9 International Classification of Diseases, 9th Revision (ICD-9) diagnosis codes identified 92% of D/OS SSI, with 1 D/OS SSI identified for every 4 cases with a diagnosis code. For hip arthroplasty, 6 ICD-9 diagnosis codes identified 99% of D/OS SSI, with 1 D/OS SSI identified for every 2 cases with a diagnosis code.
 This standardized and efficient approach for identifying D/OS SSI can be used by hospitals to improve case detection and public reporting. This method can also be used to identify potential D/OS SSI cases for review during hospital audits for data validation.
PMCID: PMC4324229  PMID: 25734174
coronary artery bypass graft surgery; hip arthroplasty; infection prevention and control programs; surgical site infection; surveillance and public reporting
9.  Which Kind of Provider’s Operation Volumes Matters? Associations between CABG Surgical Site Infection Risk and Hospital and Surgeon Operation Volumes among Medical Centers in Taiwan 
PLoS ONE  2015;10(6):e0129178.
Volume-infection relationships have been examined for high-risk surgical procedures, but the conclusions remain controversial. The inconsistency might be due to inaccurate identification of cases of infection and different methods of categorizing service volumes. This study takes coronary artery bypass graft (CABG) surgical site infections (SSIs) as an example to examine whether a relationship exists between operation volumes and SSIs, when different SSIs case identification, definitions and categorization methods of operation volumes were implemented.
A population-based cross-sectional multilevel study was conducted. A total of 7,007 patients who received CABG surgery between 2006 and 2008 from19 medical centers in Taiwan were recruited. SSIs associated with CABG surgery were identified using International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9 CM) codes and a Classification and Regression Trees (CART) model. Two definitions of surgeon and hospital operation volumes were used: (1) the cumulative CABG operation volumes within the study period; and (2) the cumulative CABG operation volumes in the previous one year before each CABG surgery. Operation volumes were further treated in three different ways: (1) a continuous variable; (2) a categorical variable based on the quartile; and (3) a data-driven categorical variable based on k-means clustering algorithm. Furthermore, subgroup analysis for comorbidities was also conducted.
This study showed that hospital volumes were not significantly associated with SSIs, no matter which definitions or categorization methods of operation volume, or SSIs case identification approaches were used. On the contrary, the relationships between surgeon’s volumes varied. Most of the models demonstrated that the low-volume surgeons had higher risk than high-volume surgeons.
Surgeon volumes were more important than hospital volumes in exploring the relationship between CABG operation volumes and SSIs in Taiwan. However, the relationships were not robust. Definitions and categorization methods of operation volume and correct identification of SSIs are important issues for future research.
PMCID: PMC4459823  PMID: 26053035
10.  Surgical site infections in Italian Hospitals: a prospective multicenter study 
Surgical site infections (SSI) remain a major clinical problem in terms of morbidity, mortality, and hospital costs. Nearly 60% of SSI diagnosis occur in the postdischarge period. However, literature provides little information on risk factors associated to in-hospital and postdischarge SSI occurrence. A national prospective multicenter study was conducted with the aim of assessing the incidence of both in-hospital and postdisharge SSI, and the associated risk factors.
In 2002, a one-month, prospective national multicenter surveillance study was conducted in General and Gynecological units of 48 Italian hospitals. Case ascertainment of SSI was carried out using standardized surveillance methodology. To assess potential risk factors for SSI we used a conditional logistic regression model. We also reported the odds ratios of in-hospital and postdischarge SSI.
SSI occurred in 241 (5.2%) of 4,665 patients, of which 148 (61.4%) during in-hospital, and 93 (38.6%) during postdischarge period. Of 93 postdischarge SSI, sixty-two (66.7%) and 31 (33.3%) were detected through telephone interview and questionnaire survey, respectively. Higher SSI incidence rates were observed in colon surgery (18.9%), gastric surgery (13.6%), and appendectomy (8.6%). If considering risk factors for SSI, at multivariate analysis we found that emergency interventions, NNIS risk score, pre-operative hospital stay, and use of drains were significantly associated with SSI occurrence. Moreover, risk factors for total SSI were also associated to in-hospital SSI. Additionally, only NNIS, pre-operative hospital stay, use of drains, and antibiotic prophylaxis were associated with postdischarge SSI.
Our study provided information on risk factors for SSI in a large population in general surgery setting in Italy. Standardized postdischarge surveillance detected 38.6% of all SSI. We also compared risk factors for in-hospital and postdischarge SSI, thus providing additional information to that of the current available literature. Finally, a large amount of postdischarge SSI were detected through telephone interview. The evaluation of the cost-effectiveness of the telephone interview as a postdischarge surveillance method could be an issue for further research.
PMCID: PMC2311314  PMID: 18328101
11.  A Systematic Review of Risk Factors Associated with Surgical Site Infections among Surgical Patients 
PLoS ONE  2013;8(12):e83743.
Surgical site infection (SSI) complicates 2-5% of surgeries in the United States. Severity of SSI ranges from superficial skin infection to life-threatening conditions such as severe sepsis, and SSIs are responsible for increased morbidity, mortality, and economic burden associated with surgery. Staphylococcus aureus (S. aureus) is a commonly-isolated organism for SSI, and methicillin-resistant S. aureus SSI incidence is increasing globally.
The objective of this systematic review was to characterize risk factors for SSI within observational studies describing incidence of SSI in a real-world setting.
Evidence Review
An initial search identified 328 titles published in 2002-2012; 57 were identified as relevant for data extraction. Extracted information included study design and methodology, reported cumulative incidence and post-surgical time until onset of SSI, and odds ratios and associated variability for all factors considered in univariate and/or multivariable analyses.
Median SSI incidence was 3.7%, ranging from 0.1% to 50.4%. Incidence of overall SSI and S. aureus SSI were both highest in tumor-related and transplant surgeries. Median time until SSI onset was 17.0 days, with longer time-to-onset for orthopedic and transplant surgeries. Risk factors consistently identified as associated with SSI included co-morbidities, advanced age, risk indices, patient frailty, and surgery complexity. Thirteen studies considered diabetes as a risk factor in multivariable analysis; 85% found a significant association with SSI, with odds ratios ranging from 1.5-24.3. Longer surgeries were associated with increased SSI risk, with a median odds ratio of 2.3 across 11 studies reporting significant results.
Conclusions and Relevance
In a broad review of published literature, risk factors for SSI were characterized as describing reduced fitness, patient frailty, surgery duration, and complexity. Recognition of risk factors frequently associated with SSI allows for identification of such patients with the greatest need for optimal preventive measures to be identified and pre-treatment prior to surgery.
PMCID: PMC3867498  PMID: 24367612
12.  Assessment of surgical site infection risk factors at Imam Reza hospital, Mashhad, Iran between 2006 and 2011 
Background: The present study was conducted to establish the patterns and risk factors of surgical site infections in our institution between 2006 and 2011.
Methods: This was a retrospective cross-sectional study. The surgical site infection (SSI) was identified based on the presence of ICD-10-CM diagnostic code in hospital discharge records. By using a standardized data collection form predictor variables including patient characteristics, preoperative, intra-operative and postoperative data were obtained.
Results: Ninety five patients fulfilled the inclusion criteria. The patients were admitted for various procedures including both elective (62.1%) and emergency (37.9%) operations. Colectomy (13.7%) was the leading procedure followed by umbilical herniation (12.6) and appendix perforation (12.6%). The mean age was 47.13 years with standard deviation of 19.60 years. Twenty percent were addicted to opium. Midline incision above and below the umbilicus (40%) had the highest prevalence of infection. Most patients (46.3%) had cleancontaminated wounds and 30.5% had contaminated one. The quantitative variables which were also measured include duration of surgery, pre-operative and post-operative hospital stay with the mean of 2.9±1.45 hours, 1.02±1.42 and 7.75±6.75 days respectively. The most antibiotics prescribed post-operatively were the combination of ceftriaxone and metronidazole (51.6%).
Conclusion: The contaminated and clean-contaminated wounds are associated with higher rate of SSIs. Also, there was a converse relation between length of surgical incision and rate of SSIs. In overall, we found type of surgery as the main risk factor in developing the SSIs.
PMCID: PMC4219881  PMID: 25405118
Risk factor; Surgical Wound Infection; Contamination; International Classification of Diseases
13.  Incidence and Risk Factors for and the Effect of a Program To Reduce the Incidence of Surgical Site Infection after Cardiac Surgery 
Surgical Infections  2014;15(3):299-304.
Background: Surgical site infection (SSI) after cardiac surgery (CS) is a serious complication that increases hospital length of stay (LOS), has a substantial financial impact, and increases mortality. The study described here was done to evaluate the effect of a program to reduce SSI after CS.
Methods: In January 2007, a multi-disciplinary CS infection-prevention team developed guidelines and implemented bundled tactics for reducing SSI. Data for all patients who underwent CS from 2006–2008 were used to determine whether there was: 1) A difference in the incidence of SSI in white patients and those belonging to minority groups; 2) a reduction in SSI after intervention; and 3) a statistically significant difference in the incidence of SSI in the third quarter of each year as compared with the other quarters of the year.
Results: Of 3,418 patients who underwent CS; 1,125 (32.9%) were members of minority groups and 2,293 (67.1%) were white. Eighty (2.3%) patients developed SSI. There was no significant difference in the incidence of SSI in non-Hispanic white patients and all others (2.1% vs. 2.8%, p=0. 42). The incidence of SSI decreased significantly from 2006 (3.0%) to 2007 (2.5%) and 2008 (1.4%), (p=0.03). Surgical site infection occurred more often in the third quarter of each of the years of the study than in other quarters of each year (3.3 vs. 2.0%, p=0.038).
Conclusions: Implementation of a program to reduce SSI after CS was associated with a lower incidence of SSI across all racial and ethnic groups and over time, but was not associated with a lower incidence of SSI in the third quarter of each year than in the other quarters.
PMCID: PMC4063380  PMID: 24800982
14.  Poor Functional Status Is an Independent Predictor of Surgical Site Infections Due to Methicillin-Resistant Staphylococcus aureus in Older Adults 
Methicillin-resistant Staphylococcus aureus (MRSA) has become a common surgical site infection (SSI) pathogen, particularly in older adults. Risk factors for MRSA SSI in elderly patients have not been described.
A nested case–control study was conducted. Patients were enrolled from seven study hospitals (one medical center and six community hospitals) between January 1, 1998, and April 1, 2003. Risk factors for MRSA SSI were identified by comparing cases with two reference groups: uninfected surgical patients and patients with SSI due to methicillin-susceptible S. aureus (MSSA). Two separate multivariate models were created using logistic regression and then compared and contrasted.
Eighty-six patients with MRSA and 64 with MSSA SSI were identified. One hundred sixty-seven uninfected surgical patients were selected. In multivariate analysis using uninfected surgical patients as controls, requiring assistance in three or more activities of daily living (ADLs) was an independent risk factor for MRSA SSI (odds ratio (OR) = 2.73, 95% confidence interval (CI) = 1.16–6.46). Using patients with MSSA SSIs as a reference group, requiring assistance in three or more ADLs was also a significant predictor for MRSA SSI (OR = 3.78, 95% CI = 1.43–9.98) in multivariate analysis. Other independent predictors included Charlson score, wound class, and surgical duration. Lack of independence in ADLs was an independent risk factor for MRSA SSI in elderly patients in both models.
Poor functional status (requiring assistance in ≥3 ADLs) was specifically associated with MRSA SSI. Functional status is an objective, readily available variable that can be used to stratify patients at risk for MRSA SSI.
PMCID: PMC2892722  PMID: 20158557
MRSA; surgical site infection; elderly
15.  A Study of Post-Caesarean Section Wound Infections in a Regional Referral Hospital, Oman 
The aim of this study was to determine the incidence of surgical site infections (SSI) in patients undergoing a Caesarean section (CS) and to identify risk factors, common bacterial pathogens and antibiotic sensitivity. SSI significantly affect the patient’s quality of life by increasing morbidity and extending hospital stays.
A retrospective cross-sectional study was conducted in Nizwa Hospital, Oman, to determine the incidence of post-Caesarean (PCS) SSI from 2001 to 2012. This was followed by a case-control study of 211 PCS cases with SSI. Controls (220) were randomly selected cases, at the same hospital in the same time period, who had undergone CS without any SSI. Data was collected on CS type, risk factors, demographic profile, type of organism, drug sensitivity and date of infection.
The total number of PCS wound infections was 211 (2.66%). There was a four-fold higher incidence of premature rupture of the membranes (37, 17.53%) and a three-fold higher incidence of diabetes (32, 15.16%) in the PCS cases compared with controls. The most common organisms responsible for SSI were Staphylococcus aureus (66, 31.27%) and the Gram-negative Escherichia coli group (40, 18.95%). The most sensitive antibiotics were aminoglycoside and cephalosporin. Polymicrobial infections were noted in 42 (19.90%), while 47 (22.27%) yielded no growth. A high incidence of associated risk factors like obesity, hypertension, anaemia and wound haematoma was noted.
Measures are recommended to reduce the incidence of SSI, including the implementation of infection prevention practices and the administration of antibiotic prophylaxis with rigorous surgical techniques.
PMCID: PMC3997538  PMID: 24790744
Caesarean Section; Surgical Wound Infections; Wounds and Injuries; Antibiotics; Risk Factors; Nosocomial Infections; Oman
16.  Stress-Induced Hyperglycemia as a Risk Factor for Surgical-Site Infection in Non-diabetic Orthopaedic Trauma Patients Admitted to the Intensive Care Unit 
Journal of orthopaedic trauma  2013;27(1):16-21.
To evaluate the association between stress-induced hyperglycemia and infectious complications in non-diabetic orthopaedic trauma patients admitted to the Intensive Care Unit (ICU).
Retrospective review.
Academic Level-1 Trauma Center.
One hundred and eighty-seven consecutive trauma patients with isolated orthopaedic injuries.
Blood glucose values during initial hospitalization were evaluated. The admission blood glucose (BG) and Hyperglycemic Index (HGI) were determined for each patient.
Main Outcome Measures
Perioperative infectious complications: pneumonia, urinary tract infection (UTI), surgical-site infection (SSI), sepsis.
An average of 21.5 BG values was obtained for each patient. Mean ICU and hospital length of stay was 4.0±4.9 and 10.0±8.1 days, respectively. Infections were recorded in 43/187 patients (23.0%) and SSI’s specifically documented in 16 patients (8.6%). Open fractures were not associated with SSI (8/83, 9.6% vs. 8/104, 7.7%). There was no difference in admission BG or HGI and infection. However, there was a significant difference in HGI when considering SSI alone (2.1±1.7 vs. 1.2±1.1). Patients with an SSI received a greater amount of blood transfusions (14.9±12.1 vs. 4.9±7.6). No patient was diagnosed with a separate infection (i.e. pneumonia, UTI, bacteremia) prior to SSI. There was no significant difference in Injury Severity Score among patients with an SSI (11.1±4.0 vs. 9.6±3.0). Multivariable regression testing with HGI as a continuous variable demonstrated a significant relationship (OR: 1.8, 95% CI: 1.3–2.5) with SSI after adjusting for blood transfusions (OR: 1.1, 95% CI: 1.1–1.2).
Stress-induced hyperglycemia demonstrated a significant independent association with SSI’s in non-diabetic orthopaedic trauma patients who were admitted to the ICU.
PMCID: PMC3507335  PMID: 22588532
hyperglycemia; orthopaedic trauma; surgical site infection; non-diabetic; intensive care unit
17.  Underweight Body Mass Index as a Predictive Factor for Surgical Site Infections after Laparoscopic Appendectomy 
Yonsei Medical Journal  2014;55(6):1611-1616.
Analyses of risk factors associated with surgical site infections (SSIs) after laparoscopic appendectomy (LA) have been limited. Especially, the association of an underweight body mass index (BMI) with SSIs has not been clearly defined. This study aimed to identify the impact of underweight BMI in predicting SSIs after LA.
Materials and Methods
The records of a total of 101 consecutive patients aged ≥16 years who underwent LA by a single surgeon between March 2011 and December 2012 were retrieved from a prospectively collected database. The rate of SSIs was compared among the underweight, normal and overweight and obese groups. Also, univariate and multivariate analyses were performed to identify the factors associated with SSIs.
The overall rate of SSIs was 12.8%. The superficial incisional SSI rate was highest in the underweight group (44.4% in the underweight group, 11.0% in the normal group, and 0% in the overweight and obese group, p=0.006). In univariate analysis, open conversion and being underweight were determined to be risk factors for SSIs. Underweight BMI was also found to be a significant predictor for SSIs in multivariate analysis (odds ratio, 10.0; 95% confidence interval, 2.0-49.5; p=0.005).
This study demonstrated underweight BMI as being associated with SSIs after LA. Surgeons should be more cautious to prevent SSIs in patients that are underweight when performing LA.
PMCID: PMC4205702  PMID: 25323899
Appendicitis; laparoscopic appendectomy; surgical site infection; body mass index; morbidity
18.  Surgical site infection prophylaxis strategies for cardiothoracic surgery: a decision-analytic model 
Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of invasive surgical site infection (SSI) in the USA. Antimicrobial prophylaxis for SSI typically includes a cephalosporin. Vancomycin is used to provide MRSA coverage, but administration timing is challenging. Linezolid is an attractive agent for SSI prophylaxis, particularly for the prevention of SSI due to MRSA.
We developed a decision-analytic model to evaluate linezolid use for cardiothoracic SSI prophylaxis. A theoretical cohort of 10,000 cardiothoracic surgery patients was followed through 2 stages: 1) occurrence of SSI, and 2) mortality after SSI. All patients were administered cefuroxime, vancomycin, or linezolid between 1–180 minutes prior to surgical incision. SSIs were categorized into three pathogen categories: 1) methicillin-susceptible Gram-positive, 2) methicillin-resistant Gram-positive, and 3) other organisms. The most effective strategy resulted in the fewest SSIs. Assumptions for antibiotic effectiveness, impact of administration time, and pathogens were based on the published literature.
Compared with cefuroxime, there was a 1% increase in the total number of SSIs in the linezolid group (mean SSI increase = 7), while there was a 12% increase in the vancomycin group (mean SSI increase = 86). Linezolid prophylaxis resulted in fewer SSIs due to methicillin-resistant Gram-positive infections (n=108) compared with cefuroxime (n = 200, 46% reduction in the linezolid group) and vancomycin (n = 119, 9% reduction in the linezolid group).
This simulation indicates that linezolid may offer benefits for SSI prophylaxis over existing prophylactic agents, particularly for the prevention of SSI due to Gram-positive methicillin-resistant pathogens.
PMCID: PMC3684012  PMID: 22831753
Surgical site infection; prophylaxis; decision-analytic model; linezolid; vancomycin
19.  Prevention and treatment of surgical site infection in HIV-infected patients 
BMC Infectious Diseases  2012;12:115.
Surgical site infection (SSI) are the third most frequently reported nosocomial infection, and the most common on surgical wards. HIV-infected patients may increase the possibility of developing SSI after surgery. There are few reported date on incidence and the preventive measures of SSI in HIV-infected patients. This study was to determine the incidence and the associated risk factors for SSI in HIV-infected patients. And we also explored the preventive measures.
A retrospective study of SSI was conducted in 242 HIV-infected patients including 17 patients who combined with hemophilia from October 2008 to September 2011 in Shanghai Public Health Clinical Center. SSI were classified according to Centers for Disease Control and Prevention (CDC) criteria and identified by bedside surveillance and post-discharge follow-up. Data were analyzed using SPSS 16.0 statistical software (SPSS Inc., Chicago, IL).
The SSI incidence rate was 47.5% (115 of 242); 38.4% incisional SSIs, 5.4% deep incisional SSIs and 3.7% organ/space SSIs. The SSI incidence rate was 37.9% in HIV-infected patients undergoing abdominal operation. Patients undergoing abdominal surgery with lower preoperative CD4 counts were more likely to develop SSIs. The incidence increased from 2.6% in clean wounds to 100% in dirty wounds. In the HIV-infected patients combined with hemophilia, the mean preoperative albumin and postoperative hemoglobin were found significantly lower than those in no-SSIs group (P<0.05).
SSI is frequent in HIV-infected patients. And suitable perioperative management may decrease the SSIs incidence rate of HIV-infected patients.
PMCID: PMC3433368  PMID: 22583551
20.  Peri-operative glycaemic control regimens for preventing surgical site infections in adults 
Surgical site infections (SSIs) are associated with significant morbidity, mortality, and resource utilization and are potentially preventable. Peri-operative hyperglycaemia has been associated with increased SSIs and previous recommendations have been to treat glucose levels above 200 mg/dL. However, recent studies have questioned the optimal glycaemic control regimen to prevent SSIs. Whether the benefits of strict or intensive glycaemic control with insulin infusion as compared to conventional management outweigh the risks remains controversial.
To summarise the evidence for the impact of glycaemic control in the peri-operative period on the incidence of surgical site infections, hypoglycaemia, level of glycaemic control, all-cause and infection-related mortality, and hospital length of stay and to investigate for differences of effect between different levels of glycaemic control.
Search strategy
A search strategy was developed to search the following databases: Cochrane Wounds Group Specialised Register (searched 25 March 2009), The Cochrane Central Register of Controlled Trials, The Cochrane Library 2009, Issue 1; Ovid MEDLINE (1950 to March Week 2 2009); Ovid EMBASE (1980 to 2009 Week 12) and EBSCO CINAHL (1982 to March Week 3 2009). The search was not limited by language or publication status.
Selection criteria
Randomised controlled trials (RCTs) were eligible for inclusion if they evaluated two (or more) glycaemic control regimens in the peri-operative period (within one week pre-, intra-, and/or post-operative) and reported surgical site infections as an outcome.
Data collection and analysis
The standard method for conducting a systematic review in accordance with the Cochrane Wounds Group was used. Two review authors independently reviewed the results from the database searches and identified relevant studies. Two review authors extracted study data and outcomes from each study and reviewed each study for methodological quality. Any disagreement was resolved by discussion or by referral to a third review author.
Main results
Five RCTs met the pre-specified inclusion criteria for this review. No trials evaluated strict glycaemic control in the immediate pre-operative period or outside the intensive care unit. Due to heterogeneity in patient populations, peri-operative period, glycaemic target, route of insulin administration, and definitions of outcome measures, combination of the results of the five included trials into a meta-analysis was not appropriate. The methodological quality of the trials was variable. In terms of outcomes, only one trial demonstrated a significant reduction in SSIs with strict glycaemic control, but the quality of this trial was difficult to assess as a result of poor reporting; furthermore the baseline rate of SSIs was high (30%). The other trials were either underpowered to detect a difference in SSIs, due to a low baseline rate (less than or equal to 5%), or did not report SSIs as a single outcome but as part of a composite. Of the three trials reporting hypoglycaemia (which was not consistently defined) all had a higher rate in the strict glycaemic control group but none attributed significant morbidity to the hypoglycaemia. Adequacy of glucose control between groups was measured differently among studies. Studies could not be compared due to differences in target ranges, and were susceptible to measurement bias due to differences in frequency of measurement and lack of blinding by the providers following the glycaemic protocols. Infection-related mortality was not reported in any of the trials, and no trials demonstrated a significant difference in all-cause mortality. Length of hospital stay was significantly reduced in the strict glycaemic control groups in only one trial.
PMCID: PMC2893384  PMID: 19588404
Hyperglycemia [complications; *prevention & control]; Hypoglycemic Agents [therapeutic use]; Insulin [therapeutic use]; Intraoperative Complications [prevention & control]; Perioperative Care; Postoperative Complications [prevention & control]; Randomized Controlled Trials as Topic; Surgical Wound Infection [etiology; *prevention & control]; Adult; Humans
21.  The Impact of Surgical Site Infection on Older Operative Patients 
To determine the impact of surgical site infection (SSI) on mortality, duration of hospitalization and hospital cost among older operative patients.
Retrospective matched outcomes study
Eight hospitals including Duke University Medical Center and 7 community hospitals.
Patients ≥ 65 years old undergoing surgery from 1991-2003. Cases were defined as patients who developed deep incisional or organ/space SSI and controls were operative patients who did not develop SSI. Controls were frequency matched to cases by type and year of operative procedure and by hospital in a 1:1 ratio.
Mortality, duration of hospitalization (including re-admissions) and hospital charges for the 90 days following surgery.
1,337 patients were enrolled in the study: 561 cases with SSI and 576 control patients without SSI. Among cases, the most common SSI pathogen was Staphylococcus aureus (n=275, 51.6%). Among S. aureus isolates, 58.2% were methicillin-resistant. One-hundred and sixteen subjects died within 90 days of surgery (8.6%). In multivariable analysis, SSI was associated with an increased mortality risk (odds ratio [OR] 3.51, 95% CI 2.20, 5.59). SSI was also associated with a 2.86 fold increase in the duration of postoperative hospitalization (95% CI 2.61, 3.13) and a 1.93 fold increase in hospital charges (95% CI 1.78, 2.10) in multivariable analysis.
Among elderly operative patients, SSI was associated with an almost 4-fold increase in mortality, a mean attributable duration of hospitalization after surgery of 15.7 days (95% CI 13.9, 17.6) and mean attributable hospital charges of $43,970 (95% CI $31,881, $56,060).
PMCID: PMC2729123  PMID: 19054183
Surgical site infection; mortality; duration of hospitalization; hospital charges
22.  Efficacy of Single-Dose Antimicrobial Prophylaxis for Preventing Surgical Site Infection in Radical Gastrectomy for Gastric Carcinoma 
Journal of Gastric Cancer  2014;14(3):156-163.
Information regarding antimicrobial prophylaxis (AMP) for gastric cancer surgery is limited. The present study investigated the efficacy of single-dose AMP for the prevention of surgical site infection (SSI) in patients undergoing gastrectomy for gastric carcinoma.
Materials and Methods
Between 2011 and 2013, 1,330 gastric carcinoma surgery patients were divided into two AMP administration groups depending on the duration of treatment. Postoperative outcomes including morbidity and SSI were compared between the two groups overall and in matched patients. Risk factors for SSI were analyzed.
The extended group (n=1,129) received AMP until postoperative day 1 and the single-dose group (n=201) received singledose AMP only during an operation. Postoperatively, there were no significant differences between the two groups with respect to overall morbidity, mortality, or length of hospital stay. The SSI rate of the single-dose group was not significantly different from that of the extended group overall (4.5% vs. 5.5%, respectively, P=0.556) or in matched patients (4.5% vs. 4.0%, respectively, P=0.801). There was no increase in the SSI rate of the single-dose group compared to the extended group in subgroups based on different clinicopathological and operative factors. Univariate and multivariate analyses revealed male gender, open surgery, and operating time (≥180 minutes) as independent risk factors for SSI.
Single-dose AMP showed no increase in the postoperative SSI rate compared to postoperative extended use in patients undergoing gastrectomy for gastric carcinoma. The efficacy of single-dose AMP requires further investigation in randomized clinical trials specific to gastric cancer surgery.
PMCID: PMC4199882  PMID: 25328760
Antibiotic prophylaxis; Surgical wound infection; Stomach neoplasms
23.  Predisposing factors for surgical site infection of spinal instrumentation surgery for diabetes patients 
European Spine Journal  2013;22(8):1854-1858.
Diabetes mellitus (DM) is known as an important risk factor for surgical site infection (SSI) in spine surgery. It is still unclear however which DM-related parameters have stronger influence on SSI. The purpose of this study is to determine predisposing factors for SSI following spinal instrumentation surgery for patients with DM.
110 DM patients (66 males and 44 females) who underwent spinal instrumentation surgery in one institute were enrolled in this study. For each patient, various preoperative or intraoperative parameters were reviewed from medical records. Patients were divided into two groups (SSI or non-SSI) based on the postoperative course. Each parameter between these two groups was compared. Univariate and multivariate analyses were performed to determine predisposing factor for SSI.
The SSI group consisted of 11 patients (10 %), and the non-SSI group of 99 patients (90 %). Univariate analysis revealed that preoperative proteinuria (p = 0.01), operation time (p = 0.04) and estimated blood loss (p = 0.02) were significantly higher in the SSI group compared to the non-SSI group. Multivariate logistic regression identified preoperative proteinuria as a statistically significant predictor of SSI (OR 6.28, 95 % CI 1.58–25.0, p = 0.009).
Proteinuria is a significant predisposing factor for SSI in spinal instrumentation surgery for DM patients. DM patients with proteinuria who are likely to suffer latent nephropathy have a potential risk for SSI. For them less invasive surgery is recommended for spinal instrumentation. In this retrospective study, there was no significant difference of preoperative condition in glycemic control between the two groups.
PMCID: PMC3731500  PMID: 23612899
Spinal instrumentation surgery; Surgical site infection; Diabetes mellitus; Proteinuria; Microvascular disease; Diabetic nephropathy
24.  Normothermia to Prevent Surgical Site Infections After Gastrointestinal Surgery: Holy Grail or False Idol? 
Annals of Surgery  2010;252(4):696-704.
To analyze the association between perioperative normothermia (temperature ≥36°C) and surgical site infections (SSIs) after gastrointestinal (GI) surgery.
Summary of Background Data
Although active warming during colorectal surgery reduces SSIs, there is limited evidence that perioperative normothermia is associated with lower rates of SSI. Nonetheless, hospitals participating in the Surgical Care Improvement Project must report normothermia rates during major surgery.
We conducted a nested, matched, case-control study; cases consisted of GI surgery patients enrolled in our National Surgical Quality Improvement Program database between March 2006 and March 2009 who developed SSIs. Patient/surgery risk factors for SSI were obtained from the National Surgical Quality Improvement Program database. Perioperative temperature/antibiotic/glucose data were obtained from medical records. Cases/controls were compared using univariate/random effects/logistic regression models. Independent risk factors for SSIs were identified using multivariate/random effects/logistic regression models.
A total of 146 cases and 323 matched controls were identified; 82% of patients underwent noncolorectal surgery. Cases were more likely to have final intraoperative normothermia compared with controls (87.6% vs. 77.8%, P = 0.015); rates of immediate postoperative normothermia were similar (70.6% vs. 65.3%, respectively, P = 0.19). Emergent surgery/higher wound class were associated with higher rates of intraoperative normothermia. Independent risk factors for SSI were diabetes, surgical complexity, small bowel surgery, and nonlaparoscopic surgery. There was no independent association between perioperative normothermia and SSI (adjusted odds ratio, 1.05; 95% confidence interval, 0.48–2.33; P = 0.90).
Pay-for-reporting measures focusing on perioperative normothermia may be of limited value in preventing SSI after GI surgery. Studies to define the benefit of active warming after noncolorectal GI surgery are warranted.
PMCID: PMC3398839  PMID: 20881777
25.  Improving Prediction of Surgical Site Infection Risk with Multilevel Modeling 
PLoS ONE  2014;9(5):e95295.
Surgical site infection (SSI) surveillance is a key factor in the elaboration of strategies to reduce SSI occurrence and in providing surgeons with appropriate data feedback (risk indicators, clinical prediction rule).
To improve the predictive performance of an individual-based SSI risk model by considering a multilevel hierarchical structure.
Patients and Methods
Data were collected anonymously by the French SSI active surveillance system in 2011. An SSI diagnosis was made by the surgical teams and infection control practitioners following standardized criteria. A random 20% sample comprising 151 hospitals, 502 wards and 62280 patients was used. Three-level (patient, ward, hospital) hierarchical logistic regression models were initially performed. Parameters were estimated using the simulation-based Markov Chain Monte Carlo procedure.
A total of 623 SSI were diagnosed (1%). The hospital level was discarded from the analysis as it did not contribute to variability of SSI occurrence (p  = 0.32). Established individual risk factors (patient history, surgical procedure and hospitalization characteristics) were identified. A significant heterogeneity in SSI occurrence between wards was found (median odds ratio [MOR] 3.59, 95% credibility interval [CI] 3.03 to 4.33) after adjusting for patient-level variables. The effects of the follow-up duration varied between wards (p<10−9), with an increased heterogeneity when follow-up was <15 days (MOR 6.92, 95% CI 5.31 to 9.07]). The final two-level model significantly improved the discriminative accuracy compared to the single level reference model (p<10−9), with an area under the ROC curve of 0.84.
This study sheds new light on the respective contribution of patient-, ward- and hospital-levels to SSI occurrence and demonstrates the significant impact of the ward level over and above risk factors present at patient level (i.e., independently from patient case-mix).
PMCID: PMC4023946  PMID: 24835189

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