Sternal Surgical Site Infection Research Articles

Blue Ribbon Abstract Award

ISSUE: Post-operative hyperglycemia is a risk factor for deep sternal surgical site infection (DS-SSI) following cardiac bypass (CB) surgery. We identified a DS-SSI rate of 4.3% (8/185) within a one year period. A medical record review of the infected patients supported poor blood glucose (BG) control as a risk factor; Mean BG was 150 mg/dl. PROJECT: Multiple glucose control protocols were examined, none deemed sufficient to attain tight glucose control. An interdisciplinary team developed an automated expert system to improve glycemic control in CB Surgery patients using a narrow target range (80-110). The protocol combines a basal insulin drip with insulin boluses, deploying a sophisticated algorithm to determine appropriate therapy based on current and previous BG level and insulin delivery rate, without immediate physician oversight. The RN-driven computer interface supplies the nurse with directions for insulin therapy that can be immediately implemented resulting in therapy that is both aggressive (38u/hr in one case) and dynamic. All BG levels for up to 5 days were collected on a cohort of CB surgery patients for 6 months pre-intervention and on all patients placed on protocol within the subsequent 15 months to determine protocol effectiveness. Medical records of all CB patients were retrospectively reviewed for 12 months pre-intervention and all protocol patients within the subsequent 15 months to evaluate length of stay, mortality, and SSI data. Costs were calculated based on a mean bed day of care (BDOC) cost. RESULTS: The number of diabetic patients in both groups was similar [38.9% (72/185); 40.7% (72/177)]. The BS target range is 80-110 and despite aggressive therapy only 7.9% (14/177) BG fell to LESSONS LEARNED: Tight glycemic control improves outcomes in CB surgery patients. It is feasible to use an aggressive approach to maintaining euglycemia with minimal physician oversight, when it is standardized, without compromising patient safety.

Rapid serodiagnosis of Staphylococcus aureus surgical site infection following median sternotomy

To determine the sensitivity and specificity of a novel ELISA for the serodiagnosis of surgical site infection (SSI) due to staphylococci following median sternotomy. Twelve patients with a superficial sternal SSI and 19 with a deep sternal SSI due to Staphylococcus aureus were compared with 37 control patients who also underwent median sternotomy for cardiac surgery but exhibited no microbiological or clinical symptoms of infection. A further five patients with sternal SSI due to coagulase-negative (CoNS) staphylococci were studied. An ELISA incorporating a recently recognised exocellular short chain form of lipoteichoic acid (lipid S) recovered from CoNS, was used to determine serum levels of anti-lipid S IgG in all patient groups. Serum anti-lipid S IgG titres of patients with sternal SSI due to S. aureus were significantly higher than the control patients (P<0.0001). In addition, patients with deep sternal SSI had significantly higher serum anti-lipid S IgG titres than patients with superficial sternal SSI (P = 0.03). Serum anti-lipid S IgG titres of patients with sternal SSI due to CoNS were significantly higher than the control patients (P = 0.001). The lipid S ELISA may facilitate the diagnosis of sternal SSI due to S. aureus and could also be of value with infection due to CoNS.

Infections after coronary artery bypass graft surgery in Victorian hospitals ‐ VICNISS Hospital Acquired Infection Surveillance

Objective: To establish a surveillance program reporting surgical site infection rates after coronary artery bypass graft surgery (CABGS) in Victorian public hospitals.Methods: The VICNISS Coordinating Centre was established in 2002 to implement and co‐ordinate a standardised surveillance system for hospital‐acquired infections in acute care Victorian public hospitals. Using validated definitions and methodology from the Centers for Disease Control and Prevention's National Nosocomial Infection Surveillance (NNIS) program, data on risk‐adjusted surgical site infection (SSI) rates were collected and submitted to the Coordinating Centre for collation and reporting.Results: Six large Melbourne metropolitan hospitals contributed data for CABGS for the period 11 November 2002 to 30 June 2004, comprising a total of 3,482 patient records. Of 3,398 complete records, the aggregate SSI rates per 100 procedures for NNIS risk category 1 and 2 were 4.4 (95% CI 3.7‐5.3) and 6.0 (95% CI 4.5–7.8) respectively. The deep sternal SSI rates were 0.6 (95% CI 0.4‐1.3) and 0.5 (95% CI 0.5‐2.4 for patients in risk category 1 and 2 respectively. The most common pathogen identified was Staphylococcus aureus.Conclusion: This early data from VICNISS demonstrates similar CABGS SSI rates to those reported by NNIS in the USA, but higher than reported by the German Nosocomial Infection Surveillance System.Implications: The adoption of a statewide, co‐ordinated surveillance program using validated internationally accepted methodologies allows hospitals to benchmark their infection rates against aggregate local and international data and to examine infection prevention interventions.

Risk Factors for Sternal and Leg Surgical Site Infections after Cardiac Surgery in Taiwan

To account for time factors related to hospitalization, the authors calculated incidence rates of surgical site infection (SSI) instead of cumulative incidence and assessed risk factors for SSI after cardiac surgery. From July 1999 to August 2000, all cardiac surgery patients in the Taipei Veterans General Hospital (Taipei, Taiwan) were invited to join the study. Data were collected by chart review, including information on patient characteristics and potential risk factors at the preoperative, intraoperative, and postoperative stages. The authors employed multiple logistic regression analyses using a generalized logit model to assess associations of interest. SSI incidence rates were 2.5 episodes per 1,000 person-days for the sternum and 3.6 episodes per 1,000 person-days for the leg. After adjustment for covariates, age (in years), gender (female vs. male), New York Heart Association classification (moderate/severe vs. normal/mild), creatinine concentration (mg/dl), and duration of surgery (in minutes) were significantly associated with sternal SSI, while age, peripheral arterial occlusive disease, and length of stay in the intensive care unit (in hours) were significantly associated with leg SSI. In addition to patients' characteristics and health situations, the significant findings for duration of surgery and length of intensive care unit stay indicate that the incidence rate is more appropriate than cumulative incidence for studying risk factors for SSI.

Sternal surgical-site infection following coronary artery bypass graft: prevalence, microbiology, and complications during a 42-month period.

Surgical-site infection (SSI) is a serious and costly complication following coronary artery bypass graft (CABG). We analyzed surgical factors, microbiology, and complications at a 608-bed community teaching hospital to identify opportunities for prevention. All patients undergoing CABG procedures from June 1997 through December 2000 were analyzed. Hospital records and postdischarge surveillance data were reviewed for demographics, surgical information, timing and classification of infection, microbiology, and bacteremic events. Of 3,443 patients undergoing CABG, sternal SSI developed in 122 (3.5%); 71 (58.2%) were classified as superficial SSI and 51 (41.8%) as deep SSI. Surgical antimicrobial prophylaxis was employed in all cases. On average, infection occurred 21.5 days (range, 4 to 315) after CABG. Most cases were diagnosed on readmission (59%); 20 cases (16%) were identified by postdischarge surveillance. Microbiological data were positive in 109 (89.3%), with a single pathogen implicated in most (86.2%). Gram-positive cocci were most frequently recovered (81%); gram-negative bacilli (17%), gram-positive bacilli (1%), and yeast (1%) were less common. Staphylococcus aureus was the most frequently isolated pathogen (49%). Bacteremia was noted in 22 instances (18%). It was significantly associated with deep SSI (P =. 002) and identified only in S. aureus cases. SSI complicated 3.5% of the procedures. S. aureus was implicated in most of the cases and was significantly associated with deep SSI. It was the only pathogen associated with secondary bacteremia. In addition to standard guidelines, targeted methods against S. aureus should help reduce the overall rate of SSI.